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GEOCHEMISTRY ARTICLES – July 2020?Analytical ChemistryBastviken, D., Nygren, J., Schenk, J., Parellada Massana, R., Duc, N.T., 2020. Technical note: Facilitating the use of low-cost methane (CH4) sensors in flux chambers – calibration, data processing, and an open-source make-it-yourself logger. Biogeosciences 17, 3659-3667.Chen, L., Li, H., Li, S., Xu, L., Lin, S., Zhou, H., 2020. Development of in-situ Micro-Raman spectroscopy system for autoclave experimental apparatus. Acta Geochimica 39, 445-450.Klimas, A., Zhao, Y., 2020. Expansion microscopy: Toward nanoscale imaging of a diverse range of biomolecules. ACS Nano 14, 7689-7695.Nikolskaya, E., Hiltunen, Y., 2020. Time-domain NMR in characterization of liquid fuels: A mini-review. Energy & Fuels 34, 7929-7934.Wang, D., He, P., Wang, Z., Li, G., Majed, N., Gu, A.Z., 2020. Advances in single cell Raman spectroscopy technologies for biological and environmental applications. Current Opinion in Biotechnology 64, 218-229.Extraction Methods/Sample PreparationChang, Q., Wang, M., Zhang, G., Zang, X., Li, H., Zhang, S., Wang, C., Wang, Z., 2020. Carbon nanospheres as solid-phase microextraction coating for the extraction of polycyclic aromatic hydrocarbons from water and soil samples. Journal of Separation Science 43, 2594-2601.Gas Chromatography/GC×GC/GC-MSCarri?o, ?.R., Marques, J., Trujillo-Rodriguez, M.J., Anderson, J.L., Rocha, S.M., 2020. Sorbent coatings for solid-phase microextraction targeted towards the analysis of death-related polar analytes coupled to comprehensive two-dimensional gas chromatography: Comparison of zwitterionic polymeric ionic liquids versus commercial coatings. Microchemical Journal 158, 105243.Dehghanizadeh, M., Cheng, F., Jarvis, J.M., Holguin, F.O., Brewer, C.E., 2020. Characterization of resin extracted from guayule (Parthenium argentatum): A dataset including GC-MS and FT-ICR MS. Data in Brief 11, 105989.Dubois, L.M., Aczon, S., Focant, J.-F., Perrault, K.A., 2020. Translation of a one-dimensional to a comprehensive two-dimensional gas chromatography method with dual-channel detection for volatile organic compound measurement in forensic applications. Analytical Chemistry 92, 10091-10098.Kumagai, S., Matsukami, A., Kabashima, F., Sakurai, M., Kanai, M., Kameda, T., Saito, Y., Yoshioka, T., 2020. Combining pyrolysis–two-dimensional gas chromatography–time-of-flight mass spectrometry with hierarchical cluster analysis for rapid identification of pyrolytic interactions: Case study of co-pyrolysis of PVC and biomass components. Process Safety and Environmental Protection 143, 91-100.Ochoa, G.S., Prebihalo, S.E., Reaser, B.C., Marney, L.C., Synovec, R.E., 2020. Statistical inference of mass channel purity from Fisher ratio analysis using comprehensive two-dimensional gas chromatography with time of flight mass spectrometry data. Journal of Chromatography A 1627, 461401.Profumo, A., Gorroni, A., Guarnieri, S.A., Mellerio, G.G., Cucca, L., Merli, D., 2020. GC-MS qualitative analysis of the volatile, semivolatile and volatilizable fractions of soil evidence for forensic application: A chemical fingerprinting. Talanta 219, 121304.Stilo, F., Gabetti, E., Bicchi, C., Carretta, A., Peroni, D., Reichenbach, S.E., Cordero, C., Curry, J.M., 2020. A step forward in the equivalence between thermal and differential-flow modulated comprehensive two-dimensional gas chromatography methods. Journal of Chromatography A 1627, 461396.Stultz, C., Jaramillo, R., Teehan, P., Dorman, F., 2020. Comprehensive two-dimensional gas chromatography thermodynamic modeling and selectivity evaluation for the separation of polychlorinated dibenzo-p-dioxins and dibenzofurans in fish tissue matrix. Journal of Chromatography A 1626, 461311.Teehan, P., Schall, M.K., Blazer, V.S., Gruber, B., Dorman, F.L., 2020. Modified QuEChERS extraction for the analysis of young-of-year smallmouth bass using GC × GC-TOFMS. Analytical Methods 12, 3697-3704.Ubukata, M., Kubo, A., Nagatomo, K., Hizume, T., Ishioka, H., Dane, A.J., Cody, R.B., Ueda, Y., 2020. Integrated qualitative analysis of polymer sample by pyrolysis–gas chromatography combined with high-resolution mass spectrometry: Using accurate mass measurement results from both electron ionization and soft ionization. Rapid Communications in Mass Spectrometry 34, e8820.Vilbaste, M., Tammekivi, E., Leito, I., 2020. Uncertainty contribution of derivatization in gas chromatography/mass spectrometric analysis. Rapid Communications in Mass Spectrometry 34, e8704.Waktola, H.D., Zeng, A.X., Chin, S.-T., Marriott, P.J., 2020. Advanced gas chromatography and mass spectrometry technologies for fatty acids and triacylglycerols analysis. TrAC Trends in Analytical Chemistry 129, 115957.Wang, F.C.-Y., 2020. Comprehensive two-dimensional gas chromatography hyphenated with a vacuum ultraviolet spectrometer to analyze diesel—a three-dimensional separation (GC × GC × VUV) approach. Energy & Fuels 34, 8012-8017.Zanella, D., Henket, M., Schleich, F., Dejong, T., Louis, R., Focant, J.-F., Stefanuto, P.-H., 2020. Comparison of the effect of chemically and biologically induced inflammation on the volatile metabolite production of lung epithelial cells by GC×GC-TOFMS. Analyst 145, 5148-5157.Imaging: AFMCao, Y.-H., Chen, W., Wang, T.-X., Yuan, Y.-N., 2020. Thermally enhanced shale gas recovery: microstructure characteristics of combusted shale. Petroleum Science 17, 1056-1066.Jubb, A.M., Birdwell, J.E., Hackley, P.C., Hatcherian, J.J., Qu, J., 2020. Nanoscale molecular composition of solid bitumen from the Eagle Ford group across a natural thermal maturity gradient. Energy & Fuels 34, 8167-8177.Imaging: SEM, TEM, HIMAbdulkareem, F.A., Radman, A., Faugere, G., Sathiavelu, S., Irfan, S.A., Padmanabhan, E., 2020. Petro-physical properties of Marcellus shale samples and their impact on CO2 adsorption: Equilibrium, kinetics, and empirical modeling study. Journal of Natural Gas Science and Engineering 81, 103423.Chandra, D., Vishal, V., 2020. A comparison of nano-scale pore attributes of Barakar Formation gas shales from Raniganj and Wardha Basin, India using low pressure sorption and FEG-SEM analysis. Journal of Natural Gas Science and Engineering 81, 103453.Chandra, D., Vishal, V., Debbarma, A., Banerjee, S., Pradhan, S.P., Mishra, M.K., 2020. Role of composition and depth on pore attributes of Barakar Formation gas shales of Ib Valley, India, using a combination of low-pressure sorption and image analysis. Energy & Fuels 34, 8085-8098.Feng, Z., Hao, F., Zhou, S., Wu, W., Tian, J., Xie, C., Cai, Y., 2020. Pore characteristics and methane adsorption capacity of different lithofacies of the Wufeng Formation–Longmaxi Formation shales, southern Sichuan Basin. Energy & Fuels 34, 8046-8062.Hajiabadi, S.H., Bedrikovetsky, P., Mahani, H., Khoshsima, A., Aghaei, H., Kalateh-Aghamohammadi, M., Habibi, S., 2020. Effects of surface modified nanosilica on drilling fluid and formation damage. Journal of Petroleum Science and Engineering 194, 107559.Hu, R., Tan, J., Dick, J., Li, L., Wang, W., 2020. Quantification of the influences of radiolarian fossils on the pore structure of Wufeng-Lungmachi gas shales (Ordovician-Silurian) in the Sichuan Basin, South China. Journal of Natural Gas Science and Engineering 81, 103442.Huang, C., Ju, Y., Zhu, H., Lash, G.G., Qi, Y., Yu, K., Feng, H., Ju, L., Qiao, P., 2020. Investigation of formation and evolution of organic matter pores in marine shale by helium ion microscope: An example from the Lower Silurian Longmaxi Shale, South China. Marine and Petroleum Geology 120, 104550.Jafarbeigi, E., Kamari, E., Salimi, F., Mohammadidoust, A., 2020. Experimental study of the effects of a novel nanoparticle on enhanced oil recovery in carbonate porous media. Journal of Petroleum Science and Engineering 195, 107602.Karnati, V.R., Munaga, T., Gonavaram, K.K., Amitava, B., 2020. Study on strength and leaching behavior of biogeochemical cemented sand. Geomicrobiology Journal 37, 670-681.Kim, T., Palmore, G.T.R., 2020. A scalable method for preparing Cu electrocatalysts that convert CO2 into C2+ products. Nature Communications 11, 3622.Li, J., Menguy, N., Roberts, A.P., Gu, L., Leroy, E., Bourgon, J., Yang, X.a., Zhao, X., Liu, P., Changela, H.G., Pan, Y., 2020. Bullet-shaped magnetite biomineralization within a magnetotactic Deltaproteobacterium: Implications for magnetofossil identification. Journal of Geophysical Research: Biogeosciences 125, e2020JG005680.Li, Q., Liu, D., Cai, Y., Zhao, B., Qiu, Y., Zhou, Y., 2020h. Scale-span pore structure heterogeneity of high volatile bituminous coal and anthracite by FIB-SEM and X-ray μ-CT. Journal of Natural Gas Science and Engineering 81, 103443.Liu, S., Tang, S., Tan, F., Zhao, C., Li, Y., Wang, S., Huo, T., 2020. Pore structure characteristics and hydrocarbon generation potential of middle Jurassic lacustrine source rocks in the Yuka depression, Qaidam Basin, NW China: Implications from petrographic and organic geochemical analyses. Journal of Natural Gas Science and Engineering 81, 103481.Liu, S.-Q., Sang, S.-X., Hu, Q.-J., Fang, H.-H., 2020. Characteristics of high-rank coal structure parallel and perpendicular to the bedding plane via NMR and X-ray CT. Petroleum Science 17, 925-938.Lu, Y.-q., Jiang, Y.-l., Wang, W., Du, J.-f., Liu, J.-d., 2020. Coupling relationship between reservoir diagenesis and hydrocarbon accumulation in Lower Cretaceous Yingcheng Formation of Dongling, Changling fault depression, Songliao Basin, Northeast China. China Geology 3, 247-261.Mari?, N., ?trba?ki, J., Mrazovac Kurili?, S., Be?koski, V.P., Niki?, Z., Ignjatovi?, S., Malba?i?, J., 2020. Hydrochemistry of groundwater contaminated by petroleum hydrocarbons: the impact of biodegradation (Vitanovac, Serbia). Environmental Geochemistry and Health 42, 1921-1935.Shan, C.a., Zhang, T., Liang, X., Hu, R., Zhao, W., 2020. Nanopore structure characteristics of high-rank vitrinite- and inertinite-coal. Acta Petrolei Sinica 41, 723-736.Shu, Y., Xu, S., Yang, F., Shu, Z., Peng, P., Huang, S., Zhen, H., 2020. The role of microfabric and laminae on pore structure and gas transport pathways of marine shales from Sichuan Basin, China. Geofluids 2020, 8844229.Song, C., Elsworth, D., 2020. Microbially induced calcium carbonate plugging for enhanced oil recovery. Geofluids 2020, 5921789.Wang, A., Cao, D., Nie, J., Qin, R., 2020. Vertical heterogeneity characteristics of pore structure for huge thick coal reservoirs: a case study of Juhugeng mining area in Qinghai province Acta Petrolei Sinica 41, 691-701.Wang, X., Zhu, Y., Song, Y., Mathews, J.P., 2020. Structure and partial ordering of terrestrial kerogen: Insight from high-resolution transmission electron microscopy. Fuel 281, 118759.Wood, J.M., Haeri-Ardakani, O., Sanei, H., Curtis, M.E., Royer, D., 2020. Application of paleoporosity and bitumen saturation concepts to tight-gas accumulations containing solid bitumen. International Journal of Coal Geology 228, 103547.Zhang, Y., Tang, D., Li, S., Cao, D., Liu, J., 2020. Deciphering multiple controls on mesopore structural heterogeneity of paralic organic-rich shales: Pennsylvanian–Lower Permian Taiyuan and Shanxi formations, Weibei Coalfield, southwestern North China. Journal of Petroleum Science and Engineering 195, 107613.Zhou, S., Yan, D., Tang, J., Pan, Z., 2020. Abrupt change of pore system in lacustrine shales at oil- and gas-maturity during catagenesis. International Journal of Coal Geology 228, 103557.Niles, S.F., Chacón-Pati?o, M.L., Putnam, S.P., Rodgers, R.P., Marshall, A.G., 2020. Characterization of an asphalt binder and photoproducts by Fourier transform ion cyclotron resonance mass spectrometry reveals abundant water-soluble hydrocarbons. Environmental Science & Technology 54, 8830-8836.Wolters, C., Flandinet, L., He, C., Isa, J., Orthous-Daunay, F.-R., Thissen, R., H?rst, S., Vuitton, V., 2020. Enhancing data acquisition for the analysis of complex organic matter in direct-infusion Orbitrap mass spectrometry using micro-scans. Rapid Communications in Mass Spectrometry 34, e8818.Imaging: Xray CTBian, H., Xia, Y., Lu, C., Qin, X., Meng, Q., Lu, H., 2020. Pore structure fractal characterization and permeability simulation of natural gas hydrate reservoir based on CT images. Geofluids 2020, erio, M., Fernández, D.E., Rendtorff, N., Cipollone, M., Zalba, P.E., Pazos, P.J., 2020. Depositional and postdepositional processes of an oil-shale analog at the microstructure scale: The Lower Cretaceous Agrio Formation, Neuquén Basin, northern Patagonia. American Association of Petroleum Geologists Bulletin 104, 1679-1705.Fan, N., Wang, J., Deng, C., Fan, Y., Wang, T., Guo, X., 2020. Quantitative characterization of coal microstructure and visualization seepage of macropores using CT-based 3D reconstruction. Journal of Natural Gas Science and Engineering 81, 103384.Hajiabadi, S.H., Bedrikovetsky, P., Mahani, H., Khoshsima, A., Aghaei, H., Kalateh-Aghamohammadi, M., Habibi, S., 2020. Effects of surface modified nanosilica on drilling fluid and formation damage. Journal of Petroleum Science and Engineering 194, 107559.Li, Q., Liu, D., Cai, Y., Zhao, B., Qiu, Y., Zhou, Y., 2020h. Scale-span pore structure heterogeneity of high volatile bituminous coal and anthracite by FIB-SEM and X-ray μ-CT. Journal of Natural Gas Science and Engineering 81, 103443.Liu, S.-Q., Sang, S.-X., Hu, Q.-J., Fang, H.-H., 2020. Characteristics of high-rank coal structure parallel and perpendicular to the bedding plane via NMR and X-ray CT. Petroleum Science 17, 925-938.Zheng, H., Kim, K., Kravchenko, A., Rivers, M., Guber, A., 2020. Testing Os staining approach for visualizing soil organic matter patterns in intact samples via X-ray dual-energy tomography scanning. Environmental Science & Technology 54, 8980-8989.Liquid Chromatography/LC-MS/SFCAbdighahroudi, M.S., Lutze, H.V., Schmidt, T.C., 2020. Development of an LC-MS method for determination of nitrogen-containing heterocycles using mixed-mode liquid chromatography. Analytical and Bioanalytical Chemistry 412, 4921-4930.Fujito, Y., Hayakawa, Y., Bamba, T., 2020. Development of a novel comprehensive analytical method for volatile compounds using supercritical fluid chromatography/mass spectrometry with a highly cross-linked styrene divinylbenzene polymer-based column. Journal of Chromatography A 1626, 461363.Guo, Z., Huang, S., Wang, J., Feng, Y.-L., 2020. Recent advances in non-targeted screening analysis using liquid chromatography - high resolution mass spectrometry to explore new biomarkers for human exposure. Talanta 219, 121339.Jin, D.-Q., Shi, S.-W., Ma, Y., Fang, Q., 2020. LC-Swan probe: An integrated in situ sampling interface for liquid chromatography separation and mass spectrometry analysis. Analytical Chemistry 92, 9214-9222.Móricz, ?.M., Lapat, V., Morlock, G.E., Ott, P.G., 2020. High-performance thin-layer chromatography hyphenated to high-performance liquid chromatography-diode array detection-mass spectrometry for characterization of coeluting isomers. Talanta 219, 121306.Müller, K., Zahn, D., Fr?mel, T., Knepper, T.P., 2020. Matrix effects in the analysis of polar organic water contaminants with HILIC-ESI-MS. Analytical and Bioanalytical Chemistry 412, 4867-4879.Schulze, S., Paschke, H., Meier, T., Muschket, M., Reemtsma, T., Berger, U., 2020. A rapid method for quantification of persistent and mobile organic substances in water using supercritical fluid chromatography coupled to high-resolution mass spectrometry. Analytical and Bioanalytical Chemistry 412, 4941-4952.Singh, R.R., Chao, A., Phillips, K.A., Xia, X.R., Shea, D., Sobus, J.R., Schymanski, E.L., Ulrich, E.M., 2020. Expanded coverage of non-targeted LC-HRMS using atmospheric pressure chemical ionization: a case study with ENTACT mixtures. Analytical and Bioanalytical Chemistry 412, 4931-4939.Vrkoslav, V., Rumlová, B., Strmeň, T., Cva?ka, J., 2020. Temperature-programmed capillary high-performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry for analysis of fatty acid methyl esters. Journal of Separation Science 43, 2579-2588.Weatherbee, S.L., Brau, T., Stoll, D.R., Rutan, S.C., Collinson, M.M., 2020. Simulation of elution profiles in liquid chromatography – IV: Experimental characterization and modeling of solute injection profiles from a modulation valve used in two-dimensional liquid chromatography. Journal of Chromatography A 1626, 461373.Wicker, A.P., Tanaka, K., Nishimura, M., Chen, V., Ogura, T., Hedgepeth, W., Schug, K.A., 2020. Multivariate approach to on-line supercritical fluid extraction – supercritical fluid chromatography - mass spectrometry method development. Analytica Chimica Acta 1127, 282-294.Mass Spectroscopy/FT-ICR MS/OrbitrapDa Silva, M.P., Kaesler, J.M., Reemtsma, T., Lechtenfeld, O.J., 2020. Absorption mode spectral processing improves data quality of natural organic matter analysis by Fourier-transform ion cyclotron resonance mass spectrometry. Journal of the American Society for Mass Spectrometry 31, 1615-1618.Dehghanizadeh, M., Cheng, F., Jarvis, J.M., Holguin, F.O., Brewer, C.E., 2020. Characterization of resin extracted from guayule (Parthenium argentatum): A dataset including GC-MS and FT-ICR MS. Data in Brief 11, 105989.Echavarri-Bravo, V., Tinzl, M., Kew, W., Cruickshank, F., Mackay, C.L., Clarke, D.J., Horsfall, L.E., 2019. High resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for the characterisation of enzymatic processing of commercial lignin. New Biotechnology 52, 1-8.Fu, Q.-L., Fujii, M., Riedel, T., 2020. Development and comparison of formula assignment algorithms for ultrahigh-resolution mass spectra of natural organic matter. Analytica Chimica Acta 1125, 247-257.Guillemant, J., Lacoue-Nègre, M., Berlioz-Barbier, A., de Oliveira, L.P., Albrieux, F., Joly, J.-F., Duponchel, L., 2020. Evaluating the benefits of data fusion and PARAFAC for the chemometric analysis of FT-ICR MS data sets from gas oil samples. Energy & Fuels 34, 8195-8205.He, C., Zhong, H., Zhang, Y., Li, Y., Chung, K.H., Fang, L., Zhang, W., Wu, B., Xu, C., Shi, Q., 2020. Organic matter in delayed coking wastewater: Molecular composition and its effect on emulsification. Fuel 279, 118432.Kasuga, I., Suzuki, M., Kurisu, F., Furumai, H., 2020. Molecular-level characterization of biodegradable organic matter causing microbial regrowth in drinking water by non-target screening using Orbitrap mass spectrometry. Water Research 184, 116130.??cki, M.K., Valkenborg, D., Startek, M.P., 2020. IsoSpec2: Ultrafast fine structure calculator. Analytical Chemistry 92, 9472-9475.Leewis, M.-C., Berlemont, R., Podgorski, D.C., Srinivas, A., Zito, P., Spencer, R.G.M., McFarland, J., Douglas, T.A., Conaway, C.H., Waldrop, M., Mackelprang, R., 2020. Life at the frozen limit: Microbial carbon metabolism across a Late Pleistocene permafrost chronosequence. Frontiers in Microbiology 11, 1753. doi: 1710.3389/fmicb.2020.01753.Liu, M., Tan, Y., Fang, K., Chen, C., Tang, Z., Liu, X., Yu, Z., 2021. Diverse molecular compositions of dissolved organic matter derived from different composts using ESI FT-ICR MS. Journal of Environmental Sciences 99, 80-89.Lu, Q., He, D., Pang, Y., Zhang, Y., He, C., Wang, Y., Zhang, H., Shi, Q., Sun, Y., 2020. Processing of dissolved organic matter from surface waters to sediment pore waters in a temperate coastal wetland. Science of The Total Environment 742, 140491.Muller, H., Alawani, N.A., Adam, F.M., 2020. Innate sulfur compounds as an internal standard for determining vacuum gas oil compositions by APPI FT-ICR MS. Energy & Fuels 34, 8260-o, F.C., Guaratini, T., Colepicolo, P., Gates, P.J., Lopes, N.P., 2020. Characteristic product ions of acetylene carotenoids by electrospray and nanospray ionization tandem mass spectrometry. Rapid Communications in Mass Spectrometry 34, e8811.Putman, J.C., Moulian, R., Barrère-Mangote, C., Rodgers, R.P., Bouyssiere, B., Giusti, P., Marshall, A.G., 2020. Probing aggregation tendencies in asphaltenes by gel permeation chromatography. Part 1: Online inductively coupled plasma mass spectrometry and offline Fourier transform ion cyclotron resonance mass spectrometry. Energy & Fuels 34, 8308-8315.Rosa, T.R., Folli, G.S., Pacheco, W.L.S., Castro, M.P., Rom?o, W., Filgueiras, P.R., 2020. DropMS: Petroleomics data treatment based in web server for high-resolution mass spectrometry. Journal of the American Society for Mass Spectrometry 31, 1483-1490.Silva, R.C., Yim, C., Radovi?, J.R., Brown, M., Weerawardhena, P., Huang, H., Snowdon, L.R., Oldenburg, T.B.P., Larter, S.R., 2020. Mechanistic insights into sulfur rich oil formation, relevant to geological carbon storage routes. A study using (+) APPI FTICR-MS analysis. Organic Geochemistry 147, 104067.Son, S., Kim, S., Yim, Y.-H., Kim, S., 2020. Reproducibility of crude oil spectra obtained with ultrahigh resolution mass spectrometry. Analytical Chemistry 94, 9465-9471.Terrell, E., Garcia-Perez, M., 2020. Novel strategy to analyze Fourier transform ion cyclotron resonance mass spectrometry data of biomass pyrolysis oil for oligomeric structure assignment. Energy & Fuels 34, 8466-8481.Wozniak, A.S., Goranov, A.I., Mitra, S., Bostick, K.W., Zimmerman, A.R., Schlesinger, D.R., Myneni, S., Hatcher, P.G., 2020. Molecular heterogeneity in pyrogenic dissolved organic matter from a thermal series of oak and grass chars. Organic Geochemistry 148, 104065.Zhang, C., Zhang, Y., Liu, M., Guan, Y.-M., Yuan, S.-H., 2020. Transformation of sulfur compounds in two typical atmospheric residues in hydrotreating via ESI FT-ICR MS. Fuel 281, 118731.Zhang, J., Brown, J., Scurr, D.J., Bullen, A., MacLellan-Gibson, K., Williams, P., Alexander, M.R., Hardie, K.R., Gilmore, I.S., Rakowska, P.D., 2020. Cryo-OrbiSIMS for 3D molecular imaging of a bacterial biofilm in its native state. Analytical Chemistry 92, 9008-9015.Zhang, J., Cao, J., Xia, L., Xiang, B., Li, E., 2020. Investigating biological nitrogen cycling in lacustrine systems by FT-ICR-MS analysis of nitrogen-containing compounds in petroleum. Palaeogeography, Palaeoclimatology, Palaeoecology 556, 109887.Zhang, X., Han, J., Zhang, X., Shen, J., Chen, Z., Chu, W., Kang, J., Zhao, S., Zhou, Y., 2020. Application of Fourier transform ion cyclotron resonance mass spectrometry to characterize natural organic matter. Chemosphere 260, 127458.Zherebker, A., Lechtenfeld, O.J., Sarycheva, A., Kostyukevich, Y., Kharybin, O., Fedoros, E.I., Nikolaev, E.N., 2020. Refinement of compound aromaticity in complex organic mixtures by stable isotope label assisted ultrahigh-resolution mass spectrometry. Analytical Chemistry 92, 9032-9038.Mass Spectroscopy/OtherAlves, M.R., Sauer, J.S., Prather, K.A., Grassian, V.H., Wilkins, C.L., 2020. Liquid sampling-atmospheric pressure glow discharge ionization as a technique for the characterization of salt-containing organic samples. Analytical Chemistry 92, 8845-8851.Ashton, G.P., Harding, L.P., Midgley, G., Parkes, G.M.B., 2020. Hot-stage microscopy - Direct Analysis in Real-time mass spectrometry (HDM) as a novel tool for monitoring thermally-driven reactions on a small scale. Analytica Chimica Acta 1128, 129-139.Gachumi, G., Purves, R.W., Hopf, C., El-Aneed, A., 2020. Fast quantification without conventional chromatography, the growing power of mass spectrometry. Analytical Chemistry 92, 8628-8637.Ji, H., Deng, H., Lu, H., Zhang, Z., 2020. Predicting a molecular fingerprint from an electron ionization mass spectrum with deep neural networks. Analytical Chemistry 92, 8649-8653.Liu, N., Ogliore, R.C., Vacher, L.G., 2020. NanoSIMS isotopic investigation of xenolithic carbonaceous clasts from the kapoeta howardite. Geochimica et Cosmochimica Acta 283, 243-264.Manheim, J.M., Milton, J.R., Zhang, Y., Kentt?maa, H.I., 2020. Fragmentation of saturated hydrocarbons upon atmospheric pressure chemical ionization is caused by proton-transfer reactions. Analytical Chemistry 92, 8883-8892.May, J.C., Knochenmuss, R., Fjeldsted, J.C., McLean, J.A., 2020. Resolution of isomeric mixtures in ion mobility using a combined demultiplexing and peak deconvolution technique. Analytical Chemistry 94, 9482-9492.Qi, W., Wang, Y., Cao, Y., Cao, Y., Guan, Q., Sun, T., Zhang, L., Guo, Y., 2020. Simultaneous analysis of fatty alcohols, fatty aldehydes, and sterols in thyroid tissues by electrospray ionization-ion mobility-mass spectrometry based on charge derivatization. Analytical Chemistry 92, 8644-8648.Schulze, B., Bader, T., Seitz, W., Winzenbacher, R., 2020. Column bleed in the analysis of highly polar substances: an overlooked aspect in HRMS. Analytical and Bioanalytical Chemistry 412, 4837-4847.Sobreira, T.J.P., Avramova, L., Szilagyi, B., Logsdon, D.L., Loren, B.P., Jaman, Z., Hilger, R.T., Hosler, R.S., Ferreira, C.R., Koswara, A., Thompson, D.H., Cooks, R.G., Nagy, Z.K., 2020. High-throughput screening of organic reactions in microdroplets using desorption electrospray ionization mass spectrometry (DESI-MS): hardware and software implementation. Analytical Methods 12, 3654-3669.Szalwinski, L.J., Holden, D.T., Morato, N.M., Cooks, R.G., 2020. 2D MS/MS spectra recorded in the time domain using repetitive frequency sweeps in linear quadrupole ion traps. 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Microbial Ecology 80, 286-295.Bhinderwala, F., Evans, P., Jones, K., Laws, B.R., Smith, T.G., Morton, M., Powers, R., 2020. Phosphorus NMR and its application to metabolomics. Analytical Chemistry 92, 9536-9545.Blevins, M.S., James, V.K., Herrera, C.M., Purcell, A.B., Trent, M.S., Brodbelt, J.S., 2020. Unsaturation elements and other modifications of phospholipids in bacteria: New insight from ultraviolet photodissociation mass spectrometry. Analytical Chemistry 92, 9146-9155.Cockell, C.S., Wilhelm, M.B., Perl, S., Wadsworth, J., Payler, S., McMahon, S., Paling, S., Edwards, T., 2020. 0.25 Ga salt deposits preserve signatures of habitable conditions and ancient lipids. Astrobiology 20, 864-877.Fraisier-Vannier, O., Chervin, J., Cabanac, G., Puech, V., Fournier, S., Durand, V., Amiel, A., André, O., Benamar, O.A., Dumas, B., Tsugawa, H., Marti, G., 2020. MS-CleanR: A feature-filtering workflow for untargeted LC–MS based metabolomics. 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A rock magnetic perspective of gas hydrate occurrences in a high-energy depositional system in the Krishna-Godavari basin, Bay of Bengal. Geo-Marine Letters 40, 525-539.Baranov, B., Galkin, S., Vedenin, A., Dozorova, K., Gebruk, A., Flint, M., 2020. Methane seeps on the outer shelf of the Laptev Sea: characteristic features, structural control, and benthic fauna. Geo-Marine Letters 40, 541-557.Unconventional ResourcesAbdulkareem, F.A., Radman, A., Faugere, G., Sathiavelu, S., Irfan, S.A., Padmanabhan, E., 2020. Petro-physical properties of Marcellus shale samples and their impact on CO2 adsorption: Equilibrium, kinetics, and empirical modeling study. Journal of Natural Gas Science and Engineering 81, 103423.Bai, Y., Huang, L., Zhao, J., 2020. Geochemical characteristics of Chang 91 source rocks of upper Triassic Yanchang formation in Zhidan-Ansai area, Ordos Basin and its significance for tight oil exploration. 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International Journal of Oil, Gas and Coal Technology 24, 466-482.Du, Y., Mehmani, A., Xu, K., Kelly, S., Balhoff, M., Torres-Verdín, C., 2020. Microfluidic diagnostics of the impact of local microfracture connectivity on hydrocarbon recovery following water injection. Water Resources Research 56, e2019WR026944.Fan, C., Li, H., Zhao, S., Qin, Q., Fan, Y., Wu, J., Zhang, J., 2020. Formation stages and evolution patterns of structural fractures in marine shale: Case study of the Lower Silurian Longmaxi Formation in the Changning area of the southern Sichuan Basin, China. Energy & Fuels.Feng, Z., Hao, F., Zhou, S., Wu, W., Tian, J., Xie, C., Cai, Y., 2020. Pore characteristics and methane adsorption capacity of different lithofacies of the Wufeng Formation–Longmaxi Formation shales, southern Sichuan Basin. Energy & Fuels 34, 8046-8062.Gai, H., Li, T., Wang, X., Tian, H., Xiao, X., Zhou, Q., 2020. Methane adsorption characteristics of overmature Lower Cambrian shales of deepwater shelf facies in Southwest China. Marine and Petroleum Geology 120, 104565.Gong, H., Zhu, C., Zhang, Y., Li, Z., San, Q., Xu, L., Li, Y., Dong, M., Hassanzadeh, H., 2020. Experimental evaluation on the oil saturation and movability in the organic and inorganic matter of shale. Energy & Fuels 34, 8063-8073.Guo, Q., Chen, X., Liuzhuang, X., Yang, Z., Zheng, M., Chen, N., Mi, J., 2020. Evaluation method for resource potential of shale oil in the Triassic Yanchang Formation of the Ordos Basin, China. Energy Exploration & Exploitation 38, 841-866.Hafiz, M., Hakhoo, N., Bhat, G.M., Kanungo, S., Thusu, B., Craig, J., Ahmed, W., 2020. Source potential and reservoir characterization of the Cambay Shale, Cambay Basin, India: Implications for tight gas and tight oil resource development. American Association of Petroleum Geologists Bulletin 104, 1707-1749.Hou, L., Ma, W., Luo, X., Liu, J., 2020. Characteristics and quantitative models for hydrocarbon generation-retention-production of shale under ICP conditions: Example from the Chang 7 member in the Ordos Basin. Fuel 279, 118497.Hu, R., Tan, J., Dick, J., Li, L., Wang, W., 2020. Quantification of the influences of radiolarian fossils on the pore structure of Wufeng-Lungmachi gas shales (Ordovician-Silurian) in the Sichuan Basin, South China. Journal of Natural Gas Science and Engineering 81, 103442.Huang, C., Ju, Y., Zhu, H., Lash, G.G., Qi, Y., Yu, K., Feng, H., Ju, L., Qiao, P., 2020. Investigation of formation and evolution of organic matter pores in marine shale by helium ion microscope: An example from the Lower Silurian Longmaxi Shale, South China. Marine and Petroleum Geology 120, 104550.Huo, Z., Tang, X., Meng, Q., Zhang, J., Li, C., Yu, X., Yang, X., 2020. Geochemical characteristics and hydrocarbon expulsion of lacustrine marlstones in the Shulu Sag, Bohai Bay Basin, eastern China: Assessment of tight oil resources. Natural Resources Research 29, 2647-2669.Li, J.-L., Zhang, T.-S., Li, Y.-J., Liang, X., Wang, X., Zhang, J.-H., Zhang, Z., Shu, H.-L., Rao, D.-Q., 2020. Geochemical characteristics and genetic mechanism of the high-N2 shale gas reservoir in the Longmaxi Formation, Dianqianbei Area, China. Petroleum Science 17, 939-953.Li, J., Li, B., Ren, C., Zhang, Y., Wang, B., 2020. An adsorption model for evaluating methane adsorption capacity in shale under various pressures and moisture. Journal of Natural Gas Science and Engineering 81, 103426.Li, Z., Zhang, J., Gong, D., Tan, J., Liu, Y., Wang, D., Li, P., Tong, Z., Niu, J., 2020. Gas-bearing property of the Lower Cambrian Niutitang Formation shale and its influencing factors: A case study from the Cengong block, northern Guizhou Province, South China. Marine and Petroleum Geology 120, 104556.Lu, M., Connell, L.D., Pan, Z., 2020. Wetting fluid behaviour with phase transition in geological nanopores: Liquid film, capillary condensation and evaporative flow. Journal of Petroleum Science and Engineering 195, 107570.Marín, P., Yang, Z., Xia, Y., Ordó?ez, S., 2020. Concentration of unconventional methane resources using microporous membranes: Process assessment and scale-up. Journal of Natural Gas Science and Engineering 81, 103420.Mo, F., Qi, Z., Yan, W., Huang, X., Li, J., 2020. Influence of water on gas transport in shale nanopores: Pore-scale simulation study. Energy & Fuels 34, 8239-8249.Peng, J., Milliken, K.L., Fu, Q., Janson, X., Hamlin, H.S., 2020. Grain assemblages and diagenesis in organic-rich mudrocks, Upper Pennsylvanian Cline shale (Wolfcamp D), Midland Basin, Texas. American Association of Petroleum Geologists Bulletin 104, 1593-1624.Rabbel, O., Mair, K., Galland, O., Grühser, C., Meier, T., 2020. Numerical modeling of fracture network evolution in organic-rich shale with rapid internal fluid generation. Journal of Geophysical Research: Solid Earth 125, e2020JB019445.Sermoud, V.M., Barbosa, G.D., Barreto, A.G., Tavares, F.W., 2020. Quenched solid density functional theory coupled with PC-SAFT for the adsorption modeling on nanopores. Fluid Phase Equilibria 521, 112700.Shu, Y., Xu, S., Yang, F., Shu, Z., Peng, P., Huang, S., Zhen, H., 2020. The role of microfabric and laminae on pore structure and gas transport pathways of marine shales from Sichuan Basin, China. Geofluids 2020, 8844229.Tinker, K., Gardiner, J., Lipus, D., Sarkar, P., Stuckman, M., Gulliver, D., 2020. Geochemistry and microbiology predict environmental niches with conditions favoring potential microbial activity in the Bakken Shale. Frontiers in Microbiology 11, 1781. doi: 1710.3389/fmicb.2020.01781.Wang, H., Tian, L., Gu, D., Li, M., Chai, X., Yang, Y., 2020. Method for calculating non-Darcy flow permeability in tight oil reservoir. Transport in Porous Media 133, 357-372.Wang, Y., Jiang, H., Ke, Y., Zhang, S., Wang, L., Wang, Y., He, C., Zhang, L., Wang, J.-Q., 2020. Investigation of pore structures in shallow Longmaxi shale, South China, via large-area electron imaging and neutron scattering techniques. Energy & Fuels 34, 7974-7984.Wood, J.M., Haeri-Ardakani, O., Sanei, H., Curtis, M.E., Royer, D., 2020. Application of paleoporosity and bitumen saturation concepts to tight-gas accumulations containing solid bitumen. International Journal of Coal Geology 228, 103547.Wu, Y., Tahmasebi, P., Lin, C., Dong, C., 2020. A comprehensive investigation of the effects of organic-matter pores on shale properties: A multicomponent and multiscale modeling. Journal of Natural Gas Science and Engineering 81, 103425.Zhang, H., Li, G., Guo, H., Zhang, W., Wang, Y., Li, W., Zhou, J., Wang, C., 2020. Applications of nuclear magnetic resonance (NMR) logging in tight sandstone reservoir pore structure characterization. Arabian Journal of Geosciences 13, 572.Zhang, P., Celia, M.A., Bandilla, K.W., Hu, L., Meegoda, J.N., 2020. A pore-network simulation model of dynamic CO2 migration in organic-rich shale formations. Transport in Porous Media 133, 479-496.Zhang, W., Chen, W., Wang, T., Yang, Y., 2020. A self-similarity transport model of gas desorption inside high maturity shale under thermal enhanced conditions. Journal of Natural Gas Science and Engineering 81, 103471.Zhang, Y., Hu, Q., Barber, T.J., Bleuel, M., Anovitz, L.M., Littrell, K., 2020. Quantifying fluid-wettable effective pore space in the Utica and Bakken oil shale formations. Geophysical Research Letters 47, e2020GL087896.Zhang, Y., Tang, D., Li, S., Cao, D., Liu, J., 2020. Deciphering multiple controls on mesopore structural heterogeneity of paralic organic-rich shales: Pennsylvanian–Lower Permian Taiyuan and Shanxi formations, Weibei Coalfield, southwestern North China. Journal of Petroleum Science and Engineering 195, 107613.Zhao, X., Zhou, L., Pu, X., Shi, Z., Han, G., Wu, J., Han, W., Zhang, W., Gao, H., Ma, J., Wang, H., 2020. Geological characteristics and exploration breakthrough of shale oil in Member 3 of Shahejie Formation of Qibei subsag, Qikou sag Acta Petrolei Sinica 41, 643-657.Zhou, S., Yan, D., Tang, J., Pan, Z., 2020. Abrupt change of pore system in lacustrine shales at oil- and gas-maturity during catagenesis. International Journal of Coal Geology 228, 103557.AbstractsAbdighahroudi, M.S., Lutze, H.V., Schmidt, T.C., 2020. Development of an LC-MS method for determination of nitrogen-containing heterocycles using mixed-mode liquid chromatography. Analytical and Bioanalytical Chemistry 412, 4921-4930. heterocycles (NCHs) are largely used as precursors for pharmaceuticals and can enter the environment. Some NCHs have been shown to be toxic, persistent, and very mobile in the environment. Thus, they have received increasing attention in the past years. However, the analysis of these polar compounds in environmental samples is still a challenge for liquid chromatography. This paper investigates the use of mixed-mode liquid chromatography (MMLC), which has reversed-phase and ion exchange characteristics for measurements of NCHs in water. NCHs with low pKa (i.e., <?2.5) display mainly reversed-phase interactions (neutral species) with the stationary phase and those with higher pKa (i.e., >?5) interact by a mixture of reversed-phase/ion exchange/HILIC mechanism. It was also shown that the presented method performs well in the quantification of the majority of the selected NCHs in surface water with MDLs between 3 and 6 μg/L, a low matrix effect and recoveries in the range of 77–96% except for pyridazine exhibiting 32% were achieved. The method was successfully employed to follow the degradation of NCHs in ozonation.Abdulkareem, F.A., Radman, A., Faugere, G., Sathiavelu, S., Irfan, S.A., Padmanabhan, E., 2020. Petro-physical properties of Marcellus shale samples and their impact on CO2 adsorption: Equilibrium, kinetics, and empirical modeling study. Journal of Natural Gas Science and Engineering 81, 103423. correlation of CO2 adsorption characteristics with the associated shale samples mineralogy, at various total organic contents, are essential for CO2 sequestration, improved oil recovery, and gas storage operations. In this work, Marcellus shale samples from the U.S.A are studied for their CO2 adsorption capacities in term of equilibrium and kinetics. A series of analyses, including total organic carbon content, X-ray diffraction, Fourier Transform Infra-red Spectroscopy, Field Emission Scanning Electron Microscopy, temperature-programmed desorption, and N2/CO2 adsorption were performed. Gravimetric adsorption technique with magnetic suspension balance at 298 K and up to 20 bars is used to conduct isothermal adsorption and desorption measurements. Considerable organic contents of ≈ 3-18 wt% are observed. Clay minerals such as calcite, illite, kaolinite and smectite are identified with up to 50 wt% ratio of some samples. Porosity and pore distribution analysis illustrate that the samples are mostly mesoporous with hysteresis supporting bottleneck or open ended-shaped pores. The temperature-programmed adsorption encouraged the phenomenon of chemisorption. Though, equilibrium isotherm modelling supported physical and chemical, heterogeneous, and multilayer adsorption. The kinetic investigation by double exponential model shows different rate of adsorption, which can be due to mineralogical alteration, physical properties or organic content. A new empirical model is developed to study the effect of relative pressure and porosity on the adsorption capacity using polynomial curve fitting technique. The model will help to predict the adsorption uptake at different operating pressures and porosity for future studies. The study can demonstrate insightful findings related to CO2 separation, sequestration and gas production for enhanced hydrocarbons recovery.Abitkazy, T., Ma, Y., Shi, K., Wu, S., Mu, L., Zhao, L., Liu, B., 2020. Hydrocarbon potential of Late Palaeozoic residual basins in the Central Asian Orogenic Belt: Insights from the tectonic evolution of the Yinggen-Ejinaqi Basin, Inner Mongolia, China. Geological Journal 55, 4997-5021. Yinggen‐Ejinaqi Basin (YEB) is located in the central‐southern part of the Central Asian Orogenic Belt (CAOB). Tectonically, the basin is situated at the intersection between the eastern and western CAOB, where Late Palaeozoic strata were well exposed. Hence, it offers a great opportunity to study the deep strata of the eastern CAOB. In this paper, based on extensive studies of Upper Palaeozoic field outcrops and reanalysis of associated geochemical and geochronological data in previous research, the local stratigraphic correlation is established, and the tectonic evolution, sedimentary filling, sedimentary characteristics, and petroleum system of the YEB are discussed. It is revealed that: (a) The filling characteristics of the Upper Palaeozoic strata in YEB are closely related to the closure of the Paleo‐Asian Ocean (PAO). YEB underwent subduction‐related compression during the initial extensional phase of the fore‐arc basin from the Viséan to the Serpukhovian (late Early Carboniferous). During the Bashkirian–Sakmarian interval (Late Carboniferous to Early Permian), it was in subduction‐related fore‐arc and postarc rifting phases. During the Artinskian–Capitanian (Early‐Middle Permian) times, it was in an intracontinental rifting‐depression phase. During the Wuchapingian (Late Permian), it was in an intracontinental compressional phase. Tectonostratigraphy, tectonic evolution, and hydrocarbon potential assessments of the study area show that the Zhusileng Hangwula‐Tost Ul tectonic zone (ZHTUTZ) and southwestern part of Querrshan‐Atasbogd tectonic zone (QATZ) are identified as the main prospective areas for the exploration in the YEB. (b) According to the tectonostratigraphic analysis, tectonic evolution and hydrocarbon system of Carboniferous–Permian in the YEB, the YEB has similar attributes to the basin province in western CAOB (e.g., Santanghu and Junggar basins) and eastern CAOB (Erlian, Songliao Basin). To explore commercial oil and gas in the deeper strata (Carboniferous–Permian) of the eastern CAOB basins, further tectonostratigraphic analyses and comprehensive assessment on hydrocarbon potentials are necessitated in the near future.Agarwal, A., Wen, T., Chen, A., Zhang, A.Y., Niu, X., Zhan, X., Xue, L., Brantley, S.L., 2020. Assessing contamination of stream networks near shale gas development using a new geospatial tool. Environmental Science & Technology 54, 8632-8639. spills in streams can impact ecosystem or human health. Typically, the public learns of spills from reports from industry, media, or government rather than monitoring data. For example, ～1300 spills (76 ≥ 400 gallons or ～1500 L) were reported from 2007 to 2014 by the regulator for natural gas wellpads in the Marcellus shale region of Pennsylvania (U.S.), a region of extensive drilling and hydraulic fracturing. Only one such incident of stream contamination in Pennsylvania has been documented with water quality data in peer-reviewed literature. This could indicate that spills (1) were small or contained on wellpads, (2) were diluted, biodegraded, or obscured by other contaminants, (3) were not detected because of sparse monitoring, or (4) were not detected because of the difficulties of inspecting data for complex stream networks. As a first step in addressing the last problem, we developed a geospatial-analysis tool, GeoNet, that analyzes stream networks to detect statistically significant changes between background and potentially impacted sites. GeoNet was used on data in the Water Quality Portal for the Pennsylvania Marcellus region. With the most stringent statistical tests, GeoNet detected 0.2% to 2% of the known contamination incidents (Na ± Cl) in streams. With denser sensor networks, tools like GeoNet could allow real-time detection of polluting events.Aguzzi, J., Flexas, M.M., Fl?gel, S., Lo Iacono, C., Tangherlini, M., Costa, C., Marini, S., Bahamon, N., Martini, S., Fanelli, E., Danovaro, R., Stefanni, S., Thomsen, L., Riccobene, G., Hildebrandt, M., Masmitja, I., Del Rio, J., Clark, E.B., Branch, A., Weiss, P., Klesh, A.T., Schodlok, M.P., 2020. Exo-ocean exploration with deep-sea sensor and platform technologies. Astrobiology 20, 897-915. of Saturn's largest moons, Enceladus, possesses a vast extraterrestrial ocean (i.e., exo-ocean) that is increasingly becoming the hotspot of future research initiatives dedicated to the exploration of putative life. Here, a new bio-exploration concept design for Enceladus' exo-ocean is proposed, focusing on the potential presence of organisms across a wide range of sizes (i.e., from uni- to multicellular and animal-like), according to state-of-the-art sensor and robotic platform technologies used in terrestrial deep-sea research. In particular, we focus on combined direct and indirect life-detection capabilities, based on optoacoustic imaging and passive acoustics, as well as molecular approaches. Such biologically oriented sampling can be accompanied by concomitant geochemical and oceanographic measurements to provide data relevant to exo-ocean exploration and understanding. Finally, we describe how this multidisciplinary monitoring approach is currently enabled in terrestrial oceans through cabled (fixed) observatories and their related mobile multiparametric platforms (i.e., Autonomous Underwater and Remotely Operated Vehicles, as well as crawlers, rovers, and biomimetic robots) and how their modified design can be used for exo-ocean exploration.Akpoveta, V.O., 2020. Process optimization of silica encapsulation technique as a unique remediation technology for the treatment of crude oil contaminated soil. Egyptian Journal of Petroleum 29, 113-119. effect of hydrocarbon pollution on soil quality is globally challenging. Addressing the menace of pollution on soil necessitates research into the development of viable remediation technique that is fast, effective, efficient and environmentally friendly; with cutting edge advantages over conventional remediation techniques. The technique was designed using a formulated silica encapsulating product and applied on soil contaminated by simulation with 10% crude oil. Soil was characterized for its physicochemical properties using standard methods, while its TPH content determined by molecular spectroscopy. Properties such as conductivity, pH and phosphorus levels were severely impacted by the hydrocarbon effect. Silica encapsulating product was formulated from sodium silicate and sodium dodecyl sulphate using proper optimization procedures. The encapsulating product (sodium silicate and SDS) were used in a ratio of 1:2. Optimum concentrations of 60,000?ppm sodium silicate solution, 120,000?ppm SDS, applied at optimum pH and temperature of 5 and 25?°C respectively were established from the process optimization of the experimental technique. The technique shows rapid response towards TPH removal, as 86.79% TPH reduction is achieved after seven days of treatment. The encapsulation process follows pseudo first order kinetics. Significant reduction in metals; Ni (0.61–0.036?mg/kg), V (0.82–0.11?mg/kg) and Cd (0.05–0.016?mg/kg) shows the efficacy of the technique, thereby providing a dual alternative for the remediation of hydrocarbons and heavy metals. The technique seems to be effective in restoring some lost soil properties as seen in pH, conductivity and total nitrogen after treatment. The environmental friendliness, cost effectiveness and merits associated with this technique gives it a unique advantage over other conventional methods; as such presents promising alternative route for remediation experts in addressing the challenges associated with hydrocarbon and metals pollution on soil. Silica encapsulation technique is therefore suitable for outright applications in real field challenges.Alcamí, A., 2020. Was smallpox a widespread mild disease? Science 369, 376-377.—caused by variola virus (VARV), a poxvirus—was one of the most virulent diseases known to humans, killing up to 30% of infected individuals and 300 million to 500 million people in the 20th century. The year 2020 commemorates the 40th anniversary of smallpox eradication, the first human disease eradicated after a global vaccination campaign led by the World Health Organization (WHO). The last samples of VARV are kept in two high-security laboratories pending destruction, and fears about reemergence or deliberate release of VARV have not subsided (1). Smallpox eradication is one of the most successful stories of public health, but the origin of the deadly virus remains an enigma. On page 391 of this issue, Mühlemann et al. (2) report the identification of VARV in archaeological remains from the Viking Age (600 to 1050 CE) that reveals new information about the origin of VARV and its evolution in human populations.The origin of modern VARV, which includes the major and minor VARV strains that caused the smallpox epidemics, is a matter of debate (3, 4). Evolutionarily successful viruses replicate and transmit without causing host pathology. High virulence is often seen when viruses transmit to another animal species, as observed with the current coronavirus disease 2019 (COVID-19) pandemic. The current hypothesis is that thousands of years ago, a variola-like virus ancestor from Africa was transmitted from rodents, which are common reservoirs of poxviruses, to humans, in which it evolved to become VARV. The genetically closest relatives to modern VARV—taterapox virus that infects gerbils and camelpox virus that infects camels—also evolved from a rodent variola-like virus ancestor in Africa (5) (see the figure).Once VARV transmitted to humans, it spread out of Africa and caused the epidemics of smallpox reported in numerous written records (1). The skin lesions seen in the mummy of Ramses V, who died in 1157 BCE, suggests that ancient Egypt was an early smallpox endemic region. The VARV genome sequences recently reported in a 17th-century Lithuanian mummy (6) and two Czech museum skin specimens from the 19th and 20th centuries (7) are related to the genomes of 47 modern VARV major and minor isolates from 1944 to 1977 (4).The study of Mühlemann et al. brings a new and challenging perspective on the origin of VARV. They recovered ancient VARV DNA sequences from archaeological human remains (teeth and bones) from northern Europe, western Russia, or the United Kingdom, dated from the Viking Age. The complete viral genomes from four samples and partial genome sequences from seven samples were assembled. Analysis of the complete viral genomes showed closest relation to the taterapox viral genome (even closer than to the modern VARV genome), supporting a rodent origin of ancient VARV. Zoonotic infections (which are derived from other animals) are illustrated by current transmission events of cowpox virus—a rodent virus that sporadically infects cows—to humans in Germany, which has increased after the cessation of smallpox vaccination (1).A notable feature of all modern VARV genomes is the inactivation (deletion, truncation, or mutation) of 29 genes involved in host immune evasion and in infection of a wider host range (4). Deletion of all these genes in VARV major and minor strains suggests that they were not required for human infection. Surrogate models of human smallpox may provide clues about the impact of these genes in VARV pathogenesis (8).Virulent poxviruses are believed to have evolved from a common ancestor encoding the full collection of about 200 genes, likely similar to cowpox virus, which causes limited pathology and infects a broad range of species (5, 9). The concept that the loss of immune evasion genes may increase virulence is counterintuitive, but it illustrates that much of the damage caused by viruses is due to excessive host immune responses. For example, poxvirus-encoded cytokine decoy receptors may dampen the cytokine storm that would otherwise cause pathology (8).One of the most unexpected observations from the study of Mühlemann et al. is the identification of ancient VARV isolates that still retained 14 immune modulatory and host range genes that were subsequently lost in modern VARV. This finding has important implications for the evolution of VARV. It suggests that the VARVs involved in early human transmission expressed many of the immune evasion and host range genes present in low-pathogenic poxviruses that are capable of infecting a variety of animal hosts. Thus, ancient VARV isolates may not have caused severe pathology. Mühlemann et al. found evidence of ancient VARV in 11 out of 525 individuals (2%) from the Viking Age. Whether these individuals died of smallpox is not known, but they probably suffered an acute infection because the virus was found in teeth and bones. Maybe ancient VARV evolved as a relatively common zoonosis that caused mild infection in humans, rodents, and perhaps other hosts for centuries.Once VARV was established in humans, the findings of Mühlemann et al. suggest that the inactivation of genes occurred gradually over the centuries, leading to the generation of a highly virulent, human-specific modern VARV that caused smallpox. Notably, different virus clades (subtypes) coexisted, and the ancient VARV sequenced from Viking corpses corresponds to an extinct clade of VARV.Moreover, viral gene inactivation follows a specific pattern, largely coincident in ancient and modern clades. Several genes show the same inactivating mutations in both VARV clades, suggesting that they were lost in a common ancestor. One of these genes encodes a soluble interleukin-1β receptor that inhibits fever in vaccinia virus (the smallpox vaccine), and its loss may have increased VARV-induced pathology (10). By contrast, a second group of genes accumulated different inactivating mutations in ancient and modern VARV clades, suggesting convergent selection that resulted in an advantage to both virus clades. There is a third group of genes inactivated in either ancient VARV or modern VARV, but the functional consequence may be the same. For example, all modern VARV isolates show inactivating mutations in three viral tumor necrosis factor receptor (vTNFR) genes and retained CrmB, which encodes a vTNFR fused to a chemokine binding domain (11), whereas ancient VARV retained another vTNFR (CrmE) and B7, a chemokine binding domain expressed independently. This combination of genes results in a similar anti-TNF and anti-chemokine—that is, anti-inflammatory—activity.Viruses can lose virulence as they adapt to a new host, as illustrated in the reduced severity of myxoma virus (a poxvirus) that was released to control the wild European rabbit population in Australia (5). A question remains to be addressed: Why did VARV evolve toward higher virulence in humans? Poxviruses do not establish persistent infections and individuals recovered from infection develop lifelong protective immunity, so poxviruses are forced to constantly infect na?ve individuals. The observed pattern of gene inactivation may have conferred to VARV a more efficient transmission and replication capacity, but perhaps the virus became extremely virulent. Maybe this drove the evolution of the modern VARV clade that caused the devastating smallpox epidemics, whereas less aggressive and less transmissible, low-pathogenic ancient VARV clades became extinct.References and Notes1. G. L. Smith, G. McFadden, Nat. Rev. Immunol. 2, 521 (2002).2. B. Mühlemann et al., Science 369, eaaw8977 (2020).3. I. V. Babkin, I. Babkina, Viruses 7, 1100 (2015).4. Y. Li et al., Proc. Natl. Acad. Sci. U.S.A. 104, 15787 (2007).5. S. L. Haller, C. Peng, G. McFadden, S. Rothenburg, Infect. Genet. Evol. 21, 15 (2014).6. A. T. Duggan et al., Curr. Biol. 26, 3407 (2016).7. P. Pajer et al., Viruses 9, 200 (2017).8. G. L. Smith et al., J. Gen. Virol. 94, 2367 (2013).9. R. C. Hendrickson, C. Wang, E. L. Hatcher, E. J. Lefkowitz, Viruses 2, 1933 (2010).10. A. Alcamí, G. L. Smith, Proc. Natl. Acad. Sci. U.S.A. 93, 11029 (1996).11. A. Alejo et al., Proc. Natl. Acad. Sci. U.S.A. 103, 5995 (2006).Algabri, M., She, Z., Jiao, L., Papineau, D., Wang, G., Zhang, C., Tang, D., Ouyang, G., Zhang, Y., Chen, G., Li, C., 2020. Apatite-glaucony association in the Ediacaran Doushantuo Formation, South China and implications for marine redox conditions. Precambrian Research 347, 105842. phosphogenic events took place in the late Paleoproterozoic and the Ediacaran, both of which followed an episode of atmospheric oxygenation. These apparent coincidences have led to suggestions that the Precambrian phosphorus cycle was partly regulated by oceanic redox conditions, although direct evidence is lacking. In this paper, we report the discovery of glaucony in drill cores from the phosphorite-rich Ediacaran Doushantuo Formation at Weng'an, South China, which provides new insights into redox conditions and geochemical cycles during the deposition and early diagenesis of the lower Doushantuo Formation. The presence of flaser and lenticular bedding in the sandstones suggests deposition in a tidally-influenced shallow water environment. Apatite is present as millimeter-scale flasers in sandstones, but more commonly as intraclastic grains. Glaucony typically occurs as interstitial aggregates cementing and replacing detrital minerals and phosphatic grains, with an upsection decrease in abundance. The Doushantuo glauconies have consistently high K2O (7.5–9.6 wt%). In particular, phosphorite-hosted glaucony has generally higher total iron (TFe2O3) than sandstone-hosted glaucony, consistent with Al3+–Fe3+ substitution in the octahedral site, as supported by Raman peaks slightly shifted towards lower wavenumbers for higher Fe content. A decrease in detrital input probably resulted in limited Al availability during early diagenesis, which in turn led to the waning of glaucony upsection. The phosphate grains do not show any negative Ce anomalies, consistent with precipitation of authigenic apatite in suboxic environments with insignificant preferential remobilisation of Ce during deposition and early diagenesis. REE + Y features show variable diagenetic REE enrichment in phosphorites, but identical concave-down patterns. The wide occurrence of glaucony cement further documents the presence of a generally suboxic early diagenetic environment on the seafloor, which was in active exchange with bottom seawater. Slight fluctuations of redox states in the porewater and bottom water would have promoted the cycling of Fe, enrichment of phosphate and REE, and extensive glaucony authigenesis. Therefore, the glaucony-bearing phosphorites in the Doushantuo Formation are a direct result of Fe-redox driven diagenesis. Apatite-glaucony association likely forms in suboxic environments and is considered as a useful mineralogical proxy for paleoredox conditions on the Precambrian ocean floors.Alhosani, A., Daraboina, N., 2020. Modeling of asphaltene deposition during oil/gas flow in wellbore. Fuel 280, 118617. deposition occurs in production lines and leads to a reduction in the production rate due to the contraction of the area. Besides, remedies to treat the deposition costs the industry a high expenditure because of the chemical and the physical removal techniques that may require a partial shutdown of the system. Therefore, it is crucial to accurately predict the rate of deposition to assist in minimizing and controlling this issue. To do so, factors contributing to the precipitation and deposition of asphaltenes must be accounted for, especially pressure and temperature. However, most models available in the literature assume a single-phase flow scenario to predict the thickness of asphaltene, which may lead to some discrepancies. Predicting pressure and temperature gradients in the wellbores during multi-phase flow using single-phase assumptions may cause a significant margin of error. In this study, a robust model is developed to predict the pressure, temperature, and asphaltene deposition simultaneously during multiphase flow in wellbores. The model predicts these variables with an acceptable margin of error when verified against experimental data available in the literature. It predicted the pressure against experimental data with a root-mean-square error of less than 1 psi for various flow patterns and the temperature profile with a root-mean-square error of 0.58 °F. Furthermore, a detailed analysis is conducted to investigate the effect of flow pattern, time, and gas flow rate on the thickness of the deposited layer of asphaltenes.Alkhafaji, M.W., Aljubouri, M.A., Al-Miamary, F.A., Connan, J., 2020. Biodegradation and the origin of surface bitumens in the Palaeocene Kolosh Formation, Northern Iraq. Arabian Journal of Geosciences 13, 554. bitumen from surface exposures of the Palaeocene Kolosh Formation in three areas (Duhok, Shaqlawa and Dokan) of northern Iraq were investigated using GC, GC-MS, carbon and hydrogen isotope ratios of aromatic, NSO and asphaltene to determine their state of alteration (biodegradation, water washing and abiotic oxidation), thermal maturity and potential source rocks. These samples have a high percentage of NSO and asphaltene and minor amounts of saturated and aromatic hydrocarbons. These bitumens have a distinguished biomarker distribution, which can be attributed to different levels of biodegradation. The samples of Group 1 are moderately biodegraded: their normal alkanes and isoprenoids have been removed, whereas their hopanes and steranes are intact or have been very slightly altered. The samples of Group 2 are heavily to very heavily biodegraded; their steranes and hopanes are degraded without the formation of 25-norhopanes. These samples are more oxidized than those of Group 1. The bitumens have different origins, and their terpane and sterane ratios indicate that they were generated by early mature marine carbonate source rocks that were likely to have originated from Jurassic–Lower Cretaceous Formations.Alnahwi, A., Kosanke, T., Loucks, R.G., Greene, J., Liu, X., Linton, P., 2020. High-resolution hyperspectral-based continuous mineralogical and total organic carbon analysis of the Eagle Ford Group and associated formations in south Texas. American Association of Petroleum Geologists Bulletin 104, 1439-1462. sensing is used to generate mineral maps of a fine-grained, vertical Eagle Ford Group cored section and underlying Buda Limestone and Del Rio Formation in south Texas. This technology produces a map that shows the distribution of minerals on the core surface. Three different cameras within the hyperspectral core-imaging system were used to image a 99.1-m (325-ft) core: a (1) line scan camera, which produces a high-resolution red–green–blue (120-μm) natural-color photograph of the dry core from the visible light spectrum; (2) short-wave infrared (SWIR) spectrometer (300–500-μm resolution); and (3) long-wave infrared (LWIR) spectrometer (300–500-μm resolution). In 2016, the introduction of a new high-resolution LWIR spectrometer made it possible to identify minerals in cores that were not detected by previous SWIR systems. High-resolution hyperspectral imaging technology using both the SWIR and LWIR spectra provides a significant step toward quantifying mineralogy and total organic carbon. Hyperspectral imaging is a powerful tool for studying textural and fabric relationships because it detects and highlights the major mineralogical changes that occur between depositional beds and among depositional features. Calcite compositional variations and cyclicity appear to be closely related. The Sr-rich calcite appears to indicate a smaller allochem size dominance as well as the slower sedimentation rates that are required for nannofossils to settle from suspension. Finally, the observed diagnostic cyclicity of the lower Eagle Ford can be related to coccolithophore productivity.Alves, M.R., Sauer, J.S., Prather, K.A., Grassian, V.H., Wilkins, C.L., 2020. Liquid sampling-atmospheric pressure glow discharge ionization as a technique for the characterization of salt-containing organic samples. Analytical Chemistry 92, 8845-8851. ionization techniques used for mass spectrometry (MS) analysis face challenges when trying to analyze organic species in a high-salt environment. Here, we present results using a recently developed ionization source, liquid sampling-atmospheric pressure glow discharge (LS-APGD), for marine-relevant salt-containing organic samples. Using two representative sample types, a triglyceride mixture and dissolved organic matter, this method is compared to traditional electrospray ionization (ESI) under saline and neat conditions. LS-APGD produced equal or higher (15%+) ion intensities than those of ESI for both salt-containing and neat samples, although important differences linked with adduct formation in high-salt conditions explain the molecular species observed. For all sample types, LS-APGD observed a higher diversity of molecules under optimized settings (0.25 mm electrode spacing at 20 mA) compared to traditional ESI. Furthermore, because the LS-APGD source ionizes molecular species in a ～1 mm3 volume plasma using a low-power source, there is the potential for this method to be applied in field studies, eliminating desalting procedures, which can be time-consuming and nonideal for low-concentration species.Angot, H., McErlean, K., Hu, L., Millet, D.B., Hueber, J., Cui, K., Moss, J., Wielgasz, C., Milligan, T., Ketcherside, D., Bret-Harte, M.S., Helmig, D., 2020. Biogenic volatile organic compound ambient mixing ratios and emission rates in the Alaskan Arctic tundra. Biogeosciences Discussions 2020, 1-39. Arctic warming, a lengthening growing season, and increasing abundance of biogenic volatile organic compounds (BVOC)-emitting shrubs are all anticipated to increase atmospheric BVOCs in the Arctic atmosphere, with implications for atmospheric oxidation processes and climate feedbacks. Quantifying these changes requires an accurate understanding of the underlying processes driving BVOC emissions in the Arctic. While boreal ecosystems have been widely studied, little attention has been paid to Arctic tundra environments. Here, we report terpenoid (isoprene, monoterpenes, and sesquiterpenes) ambient mixing ratios and emission rates from key dominant vegetation species at Toolik Field Station (TFS; 68°38'?N, 149°36'?W) in northern Alaska during two back-to-back field campaigns (summers 2018 and 2019) covering the entire growing season. Isoprene ambient mixing ratios observed at TFS fell within the range of values reported in the Eurasian taiga (0–500?pptv), while monoterpene and sesquiterpene ambient mixing ratios were respectively close to and below the instrumental quantification limit (~?2?pptv). We further quantified the temperature dependence of isoprene emissions from local vegetation including Salix spp. (a known isoprene emitter), and compared the results to predictions from the Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1). Our observations suggest a 180–215?% emission increase in response to a 3–4?°C warming. The MEGAN2.1 temperature algorithm exhibits a close fit with observations for enclosure temperatures below 30?°C. Above 30?°C, MEGAN2.1 predicts an isoprene emission plateau that is not observed in the enclosure flux measurements at TFS. More studies are needed to better constrain the warming response of isoprene and other BVOCs for a wide range of Arctic species.Antipenko, V.R., Fedyaeva, O.N., Grin’ko, A.A., Vostrikov, A.A., 2020. Structural group characteristics of resins and asphaltenes of high-sulfur natural asphaltite and products of its conversion in supercritical water. Petroleum Chemistry 60, 668-674. structural group characteristics of resins and asphaltenes, isolated from high-sulfur natural asphaltite of the Ivanovskoe oilfield in Orenburg oblast and the liquid products of its conversion in a flow of supercritical water (SCW) at 400°C and 30 MPa with and without admixture of zinc or aluminum, have been investigated. It has been shown that as a result of SCW treatment, the molecular weight of the resins and asphaltenes decreases two- to fivefold in comparison with the components of the initial asphaltite. This is determined by a decrease in the number of structural blocks in the molecules which become more compact due to the decrease both in the number of rings, predominantly naphthenic ones, in the blocks and in the number of carbon atoms in the aliphatic substituents. The fraction of aromatic carbon atoms substantially increases, and the degree of substitution of the aromatic nucleus decreases in the resins and asphaltenes isolated from the conversion products. The differences in the structural chemical characteristics of the resins and asphaltenes manifest themselves to a greater extent in the case the metal admixtures.Antoniewicz, M.R., 2020. A guide to deciphering microbial interactions and metabolic fluxes in microbiome communities. Current Opinion in Biotechnology 64, 230-237. occupy nearly all environments on Earth. These communities of interacting microorganisms are highly complex, dynamic biological systems that impact and reshape the molecular composition of their habitats by performing complex biochemical transformations. The structure and function of microbiomes are influenced by local environmental stimuli and spatiotemporal changes. In order to control the dynamics and ultimately the function of microbiomes, we need to develop a mechanistic and quantitative understanding of the ecological, molecular, and evolutionary driving forces that govern these systems. Here, we describe recent advances in developing computational and experimental approaches that can promote a more fundamental understanding of microbial communities through comprehensive model-based analysis of heterogeneous data types across multiple scales, from intracellular metabolism, to metabolite cross-feeding interactions, to the emergent macroscopic behaviors. Ultimately, harnessing the full potential of microbiomes for practical applications will require developing new predictive modeling approaches and better tools to manipulate microbiome interactions.Arbour, T.J., Gilbert, B., Banfield, J.F., 2020. Diverse microorganisms in sediment and groundwater are implicated in extracellular redox processes based on genomic analysis of bioanode communities. Frontiers in Microbiology 11, 1694. doi: 10.3389/fmicb.2020.01694. electron transfer (EET) between microbes and iron minerals, and syntrophically between species, is a widespread process affecting biogeochemical cycles and microbial ecology. The distribution of this capacity among microbial taxa, and the thermodynamic controls on EET in complex microbial communities, are not fully known. Microbial electrochemical cells (MXCs), in which electrodes serve as the electron acceptor or donor, provide a powerful approach to enrich for organisms capable of EET and to study their metabolism. We used MXCs coupled with genome-resolved metagenomics to investigate the capacity for EET in microorganisms present in a well-studied aquifer near Rifle, CO. Electroactive biofilms were established and maintained for almost 4 years on anodes poised mostly at ?0.2 to ?0.25 V vs. SHE, a range that mimics the redox potential of iron-oxide minerals, using acetate as the sole carbon source. Here we report the metagenomic characterization of anode-biofilm and planktonic microbial communities from samples collected at timepoints across the study period. From two biofilm and 26 planktonic samples we reconstructed draft-quality and near-complete genomes for 84 bacteria and 2 archaea that represent the majority of organisms present. A novel Geobacter sp. with at least 72 putative multiheme c-type cytochromes (MHCs) was the dominant electrode-attached organism. However, a diverse range of other electrode-associated organisms also harbored putative MHCs with at least 10 heme-binding motifs, as well as porin-cytochrome complexes and e-pili, including Actinobacteria, Ignavibacteria, Chloroflexi, Acidobacteria, Firmicutes, Beta- and Gammaproteobacteria. Our results identify a small subset of the thousands of organisms previously detected in the Rifle aquifer that may have the potential to mediate mineral redox transformations.Ardakani, O.H., Hlohowskyj, S.R., Chappaz, A., Sanei, H., Liseroudi, M.H., Wood, J.M., 2020. Molybdenum speciation tracking hydrocarbon migration in fine-grained sedimentary rocks. Geochimica et Cosmochimica Acta 283, 136-148. (Mo) systematics (i.e., total concentration and isotope ratios) are widely used for the reconstruction of paleo-redox conditions in sedimentary records. However, the geochemical processes affecting the distribution of Mo in carbonaceous fine-grained sedimentary rocks remain unclear. This study investigates how the organic matter type may control Mo concentration and speciation in siltstone/shale strata of the Lower Triassic Montney Formation in the Western Canadian Sedimentary Basin (WCSB) to identify the effects of hydrocarbon expulsion and migration, fluid/rock interactions, and thermal maturity on Mo geochemistry when used as a paleo-redox proxy.The bulk Mo concentration in the studied samples varies from 0.2 to 86?ppm (mean?=?13?±?16.7?ppm), with Mo enrichment factors of 22.7?±?24.4 suggesting an anoxic paleo-depositional setting. The X-ray Absorption Near Edge Spectroscopy (XANES) results show the presence of two separate Mo species within distinct geographic locations: (1) a group with a higher average Mo oxidation state where Mo is mostly surrounded by oxygen (O) atoms in an octahedral configuration, and (2) a group showing a lower average Mo oxidation state where Mo is mostly surrounded by sulfur (S) atoms in a tetrahedral configuration.The reduced Mo species are distributed in the vicinity of fault-related hydrothermal diagenesis/dolomitization zones. In contrast, the oxidized Mo species are found associated with samples enriched with solid bitumen/pyrobitumen. The results of our study show Mo speciation can significantly help to elucidate complex paleo-redox histories.Arnscheidt, C.W., Rothman, D.H., 2020. Routes to global glaciation. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, 20200303. and observation suggest that Earth and Earth-like planets can undergo runaway low-latitude glaciation when changes in solar heating or in the carbon cycle exceed a critical threshold. Here, we use a simple dynamical-system representation of the ice–albedo feedback and the carbonate–silicate cycle to show that glaciation is also triggered when solar heating changes faster than a critical rate. Such ‘rate-induced glaciations’ remain accessible far from the outer edge of the habitable zone, because the warm climate state retains long-term stability. In contrast, glaciations induced by changes in the carbon cycle require the warm climate state to become unstable, constraining the kinds of perturbations that could have caused global glaciation in Earth’s past. We show that glaciations can occur when Earth’s climate transitions between two warm stable states; this property of the Earth system could help explain why major events in the development of life have been accompanied by glaciations.Asaoka, S., Jadoon, W.A., Umehara, A., Takeda, K., Otani, S., Ohno, M., Fujitake, N., Sakugawa, H., Okamura, H., 2020. Organic matter degradation characteristics of coastal marine sediments collected from the Seto Inland Sea, Japan. Marine Chemistry 225, 103854. matter in marine sediment is mainly categorized into three fractions depending on degradability: labile, semi labile and refractory. The degradability of coastal marine sediments depends on the properties of the organic matter contained in the sediments. The purpose of this study was to quantify labile and refractory organic matter in coastal marine sediments with different characteristics collected from the Seto Inland Sea, and to discover the factors controlling the degradability of organic matter. Refractory organic matter content in sediments ranged from 4.7–21.4 mg g?1, a percent composition equivalent to 72–97% of TOC. In contrast, labile and semi-labile content were 0.1–1.4 mg g?1 and 0.1–2.3 mg g?1, respectively, a percent composition equivalent to 0.5–12.9% and 1.8–17.1% of TOC, respectively. Approximately 93% of refractory organic matter was categorized into humin. Organic matter originated from marine phytoplankton settled on the surface of sediments and changed to humin or a refractory organic matter. This study contributes to a better understanding of the organic matter degradation characteristics of coastal marine sediments and provides important parameters for estimating carbon budget and carbon cycling in coastal sea systems.Asemani, M., Rabbani, A.R., Sarafdokht, H., 2020. Evaluation of oil fingerprints similarity by a novel technique based on FTIR spectroscopy of asphaltenes: Modified moving window correlation coefficient technique. Marine and Petroleum Geology 120, 104542. of oil fingerprints heterogeneities in different wells across the reservoir is a critical effort in various disciplines of geochemical studies. Exploring new, trustworthy, and straightforward techniques is an ongoing and interesting subject in the oil industry. In this paper, a novel procedure for oil fingerprints comparison by employing the structural characteristics of asphaltenes is suggested. For the first time, the modified version of the moving window correlation coefficient is proposed to resolve the drawbacks of the standard procedure and then implementing for comparison of oil fingerprints. This procedure is based on peak ratios calculated from the second derivative FTIR spectra of asphaltene samples. The results of this technique are summarized in a matrix with green, red and yellow cells based on the calculated values of the minimum correlation coefficient in all moving windows (MMWR) and the average of correlation coefficients in all moving windows (AMWR) regarding defined thresholds to better visualization of fingerprint similarity or dissimilarity between studied samples. The oil fingerprint similarities in the two case studies from the Dezful Embayment of southwest Iran were investigated to demonstrate the usefulness of this technique. Ten samples from different wells in the Qale Nar oil field and eight samples from the Shadegan oil field were studied. Results showed that crude oils in the Asmari reservoir from the Qale Nar field have a similar fingerprint and are homogenous. But crude oils in the Asmari reservoir from the Shadegan field involves several zones based on oil fingerprints similarity. Whole oil gas chromatography (WOGC) was performed for checking purposes. The proposed method based on FTIR spectra of asphaltene samples and their comparison with the modified moving window correlation coefficient can be regarded as a novel, reliable, and straightforward technique for oil fingerprint similarity assessment.Ashton, G.P., Harding, L.P., Midgley, G., Parkes, G.M.B., 2020. Hot-stage microscopy - Direct Analysis in Real-time mass spectrometry (HDM) as a novel tool for monitoring thermally-driven reactions on a small scale. Analytica Chimica Acta 1128, 129-139. is a requirement for reliable real-time analytical tools for reaction monitoring to optimise chemical syntheses. We have developed a new technique which combines thermal analysis, digital microscopy and chemical identification using ambient ionisation mass spectrometry. We term this hot-stage microscopy-Direct Analysis in Real-Time mass spectrometry (HDM). The technique provides optical data as a function of temperature coupled with chemical characterisation of evolved species, including reactants, intermediates and products throughout the course of a reaction. In addition, only a few milligrams of sample are required with analyte detection down to the nanogram range. We demonstrate the benefits of HDM using a series of solvent-free reactions. Our results confirm the suitability of the technique as the reactions studied follow the same pathways as published previously. The accurate temperature control achieved with HDM could also be used to assess the optimum temperature at which thermally-driven reactions can proceed efficiently.Asta, M.P., Beller, H.R., O’Day, P.A., 2020. Anaerobic dissolution rates of U(IV)-oxide by abiotic and nitrate-dependent bacterial pathways. Environmental Science & Technology 54, 8010-8021. long-term stability of U(IV) solid phases in anaerobic aquifers depends upon their reactivity in the presence of oxidizing chemical species and microbial catalysts. We performed flow-through column experiments under anaerobic conditions to investigate the mechanisms and dissolution rates of biogenic, noncrystalline UO2(s) by chemical oxidants (nitrate and/or nitrite) or by Thiobacillus denitrificans, a widespread, denitrifying, chemolithoautotrophic model bacterium. Dissolution rates of UO2(s) with dissolved nitrite were approximately 5 to 10 times greater than with nitrate alone. In the presence of wild-type T. denitrificans and nitrate, UO2(s) dissolution rates were similar to those of abiotic experiments with nitrite (from 1.15 × 10–14 to 4.94 × 10–13 mol m–2 s–1). Experiments with a T. dentrificans mutant strain defective in U(IV) oxidation supported microbially mediated U(IV) oxidation. X-ray absorption spectroscopy (XAS) analysis of post-reaction solids showed the presence of mononuclear U(VI) species rather than a solid U(VI) phase. At steady-state U release, kinetic and spectroscopic results suggest detachment of oxidized U(VI) from the UO2(s) surface as the rate-determining step rather than electron transfer or ion diffusion. Under anaerobic conditions, production of nitrite by nitrate-reducing microorganisms and enzymatically catalyzed, nitrate-dependent U(IV) oxidation are likely dual processes by which reduced U solids may be oxidized and mobilized in the aqueous phase.Aubé, J., Senin, P., Bonin, P., Pringault, O., Jeziorski, C., Bouchez, O., Klopp, C., Guyoneaud, R., Go?i-Urriza, M., 2020. Meta-omics provides insights into the impact of hydrocarbon contamination on microbial mat functioning. Microbial Ecology 80, 286-295. microbial mats are stable, self-supported communities. Due to their coastal localization, these mats are frequently exposed to hydrocarbon contamination and are able to grow on it. To decipher how this contamination disturbs the functioning of microbial mats, we compared two mats: a contaminated mat exposed to chronic petroleum contamination and a reference mat. The taxonomic and metabolic structures of the mats in spring and fall were determined using metagenomic and metatranscriptomic approaches. Extremely high contamination disturbed the seasonal variations of the mat. ABC transporters, two-component systems, and type IV secretion system-related genes were overabundant in the contaminated mats. Xenobiotic degradation metabolism was minor in the metagenomes of both mats, and only the expression of genes involved in polycyclic aromatic hydrocarbon degradation was higher in the contaminated mat. Interestingly, the expression rates of genes involved in hydrocarbon activation decreased during the 1-year study period, concomitant with the decrease in easily degradable hydrocarbons, suggesting a transient effect of hydrocarbon contamination. Alteromonadales and Oceanospirillales hydrocarbonoclastic bacteria appeared to be key in hydrocarbon remediation in the contaminated mat. Overall, the contaminated microbial mat was able to cope with hydrocarbon contamination and displayed an adaptive functioning that modified seasonal behaviour.Auersvald, M., Macek, T., Schulzke, T., Sta?, M., ?imá?ek, P., 2020. Influence of biomass type on the composition of bio-oils from ablative fast pyrolysis. Journal of Analytical and Applied Pyrolysis 150, 104838. of the easiest ways to minimize the overall costs of bio-oil production is to minimize biomass transportation and, thus, pyrolysis should be performed at or close to the biomass original location. Thus, we applied ablative fast pyrolysis (AFP), as the only potentially mobile pyrolysis unit, to convert residual lignocellulosic biomass into bio-oil. Four different biomass types were converted to bio-oils: beech and poplar wood, straw and miscanthus. To study reliably the influence of biomass type on bio-oil yields, physicochemical properties and composition, pyrolysis was carried out at a constant temperature of 550?°C. Titrations and spectroscopic methods were used for the characterization of the main oxygenate groups. GC-MS was used for the quantification of more than 120 volatile compounds. Such a thorough analytical study of AFP bio-oils, heretofore missing in scientific literature, allowed us to reliably discuss the differences in bio-oils? relative to the knowledge of biomass composition. Significant differences between the bio-oils were observed, with the lowest content of carboxylic and carbonyl groups in the straw bio-oil. The amount of carboxylic and phenolic groups in all the bio-oils was in the typical range observed for bio-oils unlike the carbonyls? and levoglucosan content, which was lower than typical for bio-oils from other pyrolysis units.Aziz, H., Ehsan, M., Ali, A., Khan, H.K., Khan, A., 2020. Hydrocarbon source rock evaluation and quantification of organic richness from correlation of well logs and geochemical data: A case study from the Sembar Formation, Southern Indus Basin, Pakistan. Journal of Natural Gas Science and Engineering 81, 103433. Formation of Cretaceous encountered in Khajari-01 and Miran-01 wells, which are located in the Southern Indus Basin (SIB), Pakistan. Total organic carbon (TOC) content is generally measured by traditional methods such as the evaluation of side wall cores and formation cuttings in a geochemical lab. Data obtained from these experimental techniques are not continuous and also a time-consuming process. A solution to this problem is high resolution and continuous information obtained from well logs. Different methods were used to estimate TOC through well logs. Among those methods, four methods have been chosen to estimate TOC in the current research, i.e., Density Log, Spectral Gamma-Ray Log, ΔlogR, and Multivariate Fitting methods. The TOC estimated values have been correlated with well cuttings TOC values to optimize a method for TOC estimation through well logs. Fourteen well cutting samples of Sembar Formation from Khajari-01 well and seven samples from Miran-01 well have been selected for measurements of geochemical parameters. These parameters were used for source rock evaluation of the formation to determine the quality, quantity, and maturity of the Sembar Formation. Modified van-Krevlen diagram of Hydrogen Index (HI) versus Oxygen Index (OI) and Langford diagram of S2 versus TOC indicates that Sembar Formation in Khajari-01 well contain kerogen type-III (gas prone) compare to Miran-01 well that contains kerogen type-IV which makes it non-productive. The organic richness results indicate that TOC in Khajari-01 well is poor to very good while in Miran-01 a fair to good generation potential exist. Maturity indicators i.e., Pyrolysis Temperature (Tmax) and Production Index (PI) values show an immature to early mature zone for Khajari-01 well and over-mature zone in Miran-01 within the Sembar Formation. Density Log, Spectral Gamma-Ray Log, and Multivariate Fitting methods have poor coefficient of determination (R2) values between the estimated TOC (from well logs) with well cuttings tested samples TOC values. It has been inferred from data obtained using ΔlogR method that it has good R2 value between well logs estimated TOC and actual laboratory measured TOC in both wells which is optimized for future study in Southern Indus Basin, Pakistan.Badesab, F., Dewangan, P., Gaikwad, V., Sebastian, J.G., Venkateshwarlu, M., 2020. A rock magnetic perspective of gas hydrate occurrences in a high-energy depositional system in the Krishna-Godavari basin, Bay of Bengal. Geo-Marine Letters 40, 525-539. conducted a detailed rock magnetic study complemented by sedimentological and mineralogical methods on a 177.2-m-long sediment core of Hole NGHP-01-14A to constrain the influence of high-energy depositional environment on the magnetic mineral diagenesis and formation of gas hydrates in the Krishna-Godavari (K-G) basin, Bay of Bengal. Five sediment magnetic zones were identified based on the downcore variation in rock magnetic parameters. The magnetic mineralogies comprised of detrital titanomagnetite, diagenetically formed magnetic iron sulfides and their mixture. A distinct magnetically enhanced zone (Z-3) close to a bottom simulating reflector (BSR) is dominated by higher magnetite content, sediment bulk density, and grain size and probably represents several sand-rich sediment layers formed as a result of short-duration intense sedimentation events and got rapidly buried and provided conducive environment for the formation of gas hydrate deposits at the studied site. The concurrence of gas hydrates and high gas saturations within the sand-rich layers (Z-3) suggests that the high-energy depositional environment had a larger control over hydrate formation at Hole NGHP-01-14A. Two magnetic iron sulfide bearing sediment intervals in Z-1b and Z-1c below sulfate-methane transition zone (SMTZ) suggest that their formation is controlled by microbially mediated diagenetic reactions fuelled by presence of gas hydrates and probably represents the fossil gas hydrate zones. We propose that the rock magnetic variations in the studied sediment core at Hole NGHP-01-14A is controlled by both differential loading of detrital magnetic minerals as well as hydrate-induced late diagenetic magnetic iron sulfide formation.Badesab, F., Gaikwad, V., Dewangan, P., 2020. Controls on greigite preservation in a gas hydrate system of the Krishna-Godavari basin, Bay of Bengal. Geo-Marine Letters 40, 439-452. sediments across large parts of Krishna-Godavari (K-G) basin offshore east central Indian contain abundant methane and gas hydrates. In this study, we carried out rock-magnetic and transmission electron microscope (TEM) analyses on the samples from a sediment core (MD161/Stn-8) to constrain the formation and preservation of greigite in shallow sediments and how this might link to reactions involving methane. Here, we report for the first time the occurrence of silicate-hosted iron sulfide (greigite) inclusions which is an important observation for understanding the preservation of magnetic minerals in gas hydrate systems. The magnetization of the greigite zone (17–23 mbsf) is carried by complex magnetic mineral assemblages of detrital iron oxides (titanomagnetite), diagenetic iron sulfide (greigite) occurring as nano-inclusions within larger silicate particles, and biogenic minerals. Elevated concentrations of dissolved pore water silica and alkalinity within the magnetically enhanced greigite zone suggest that silica diagenesis and silicate weathering triggered by paleo-methane seepage played a key role in crystallizing the diagenetically formed iron sulfide (greigite) into silicate matrix. The silicate-hosted magnetic inclusions protected the ferrimagnetic greigite from further diagenetic dissolution and prevented its conversion into stable pyrite. Three scenarios explaining the potential controls on the greigite preservation in gas hydrate marine sedimentary system have been proposed.Bai, Y., Huang, L., Zhao, J., 2020. Geochemical characteristics of Chang 91 source rocks of upper Triassic Yanchang formation in Zhidan-Ansai area, Ordos Basin and its significance for tight oil exploration. Petroleum Science and Technology 38, 524-534. average total organic carbon (TOC) content of Chang 91 source rocks is 4.85%, and the main kerogen type is II1, and the average pyrolysis peak temperature is 452?°C in Zhidan-Ansai area, Ordos Basin. These show that Chang 91 source rocks have reached good to excellent level and peak hydrocarbon generation stage. Chang 91 source rocks were formed in semi-deep lacustrine sedimentary environments of fresh-brackish water and weak oxidation-reduction. The discovery of Chang 91 source rock extends the oil exploration field of Yanchang Formation, especially in Zhidan area, it is a favorable area for further exploration in Chang 9 reservoir.Bajagain, R., Gautam, P., Jeong, S.-W., 2020. Degradation of petroleum hydrocarbons in unsaturated soil and effects on subsequent biodegradation by potassium permanganate. Environmental Geochemistry and Health 42, 1705-1714. date, the oxidation of petroleum hydrocarbons using permanganate has been investigated rarely. Only a few studies on the remediation of unsaturated soil using permanganate can be found in the literature. This is, to the best of our knowledge, the first study conducted using permanganate pretreatment to degrade petroleum hydrocarbons in unsaturated soil in combination with subsequent bioaugmentation. The pretreatment of diesel-contaminated unsaturated soil with 0.5-pore-volume (5%) potassium permanganate (PP) by solution pouring and foam spraying (with a surfactant) achieved the total petroleum hydrocarbon (TPH) removal efficiencies of 37% and 72.1%, respectively. The PP foam, when coupled with bioaugmentation foam, further degraded the TPH to a final concentration of 438 mg/kg (92.1% total reduction). The experiment was conducted without soil mixing or disturbance. The relatively high TPH removal efficiency achieved by the PP–bioaugmentation serial foam application may be attributed to an increase in soil pH caused by the PP and effective infiltration of the remediation agent by foaming. The applied PP foam increased the pH of the acidic soil, thus enhancing microbial activity. The first-order biodegradation rate after PP oxidation was calculated to be 0.068 d?1. Furthermore, 94% of the group of relatively persistent hydrocarbons (C18–C22) was removed by PP–bioaugmentation, as verified by chromatogram peaks. Some physicochemical parameters related to contaminant removal efficiency were also evaluated. The results reveal that PP can degrade soil TPH and significantly enhance the biodegradation rate in unsaturated diesel-contaminated soil when combined with bioaugmentation foam.Baldwin, A.K., Corsi, S.R., Oliver, S.K., Lenaker, P.L., Nott, M.A., Mills, M.A., Norris, G.A., Paatero, P., 2020. Primary sources of polycyclic aromatic hydrocarbons to streambed sediment in Great Lakes tributaries using multiple lines of evidence. Environmental Toxicology and Chemistry 39, 1392-1408. aromatic hydrocarbons (PAHs) are among the most widespread and potentially toxic contaminants in Great Lakes (USA/Canada) tributaries. The sources of PAHs are numerous and diverse, and identifying the primary source(s) can be difficult. The present study used multiple lines of evidence to determine the likely sources of PAHs to surficial streambed sediments at 71 locations across 26 Great Lakes Basin watersheds. Profile correlations, principal component analysis, positive matrix factorization source‐receptor modeling, and mass fractions analysis were used to identify potential PAH sources, and land‐use analysis was used to relate streambed sediment PAH concentrations to different land uses. Based on the common conclusion of these analyses, coal‐tar–sealed pavement was the most likely source of PAHs to the majority of the locations sampled. The potential PAH‐related toxicity of streambed sediments to aquatic organisms was assessed by comparison of concentrations with sediment quality guidelines. The sum concentration of 16 US Environmental Protection Agency priority pollutant PAHs was 7.4–196?000??g/kg, and the median was 2600??g/kg. The threshold effect concentration was exceeded at 62% of sampling locations, and the probable effect concentration or the equilibrium partitioning sediment benchmark was exceeded at 41% of sampling locations. These results have important implications for watershed managers tasked with protecting and remediating aquatic habitats in the Great Lakes Basin.Bao, R., Blattmann, T.M., 2020. Radiocarbonscapes of sedimentary organic carbon in the East Asian Seas. Frontiers in Marine Science 7, :517. doi: 10.3389/fmars.2020.00517. abundance radiocarbon (14C) is an increasingly widely used tool for investigating the organic carbon (OC) cycle in the contemporary ocean. Recent studies have provided extensive information on the 14C characteristics of organic matter (OM) in sinking particles and sediments in the East Asian Seas including studies from the Bohai Sea, Yellow Sea, East China Sea, South China Sea, Japan Sea, and Japan Trench. 14C investigations have provided insights into biogeochemical processes controlling the fate of sedimentary OM in these settings. Here, we highlight these insights from oceanic landscapes stretching across deltas, shelves, abyssal oceans, and the hadal zones of the East Asian Seas; share our perspectives on the source-to-sink dynamics of sedimentary OM in the ocean; and outline the challenges that need to be faced to make the most out of interpreting 14C signals in sedimentary OC.Baranov, B., Galkin, S., Vedenin, A., Dozorova, K., Gebruk, A., Flint, M., 2020. Methane seeps on the outer shelf of the Laptev Sea: characteristic features, structural control, and benthic fauna. Geo-Marine Letters 40, 541-557. areas with cold methane seeps on the outer shelf of the Laptev Sea were studied by two interdisciplinary expeditions onboard the RV Akademik Mstislav Keldysh in August–September of 2017 and 2018. These fields lie in water between depths of 63 and 73 m, and in a region of growing interest to the international community. Characteristic features of the methane seeps were obtained, which include their distribution and appearance on the seabed based on acoustic anomalies and seafloor observations. The cold seeps are part of a domain striking in a SW–NE direction along the Laptev Sea Rift System, Khatanga–Lomonosov Fracture Zone, and the Gakkel Ridge junction, and its structure was determined by shallow faults on the outer shelf. These faults are related to subsidence of the outer shelf cutting the caprock formed by permafrost and gas hydrates. Faults serve as conduits for an intense bubble methane discharge at the seabed. Shallow-water methane seep fauna were described for the first time in the Siberian Arctic. The frenulate siboglinid tubeworm Oligobrachia haakonmosbiensis was among the dominant species of the methane seep communities. A newly discovered gastropod species Frigidalvania sp. was also found in abundance at the seeps as well as an ophiuroid Ophiocten sericeum. Significant differences were observed between benthic communities of the two seep fields and background fauna including integral community parameters and the presence/absence of certain species. Development of shallow methane seep communities in the Laptev Sea apparently is related to extremely oligotrophic conditions in this area.Barido-Sottani, J., van Tiel, N.M.A., Hopkins, M.J., Wright, D.F., Stadler, T., Warnock, R.C.M., 2020. Ignoring fossil age uncertainty leads to inaccurate topology and divergence time estimates in time calibrated tree inference. Frontiers in Ecology and Evolution 8, 183. doi: 10.3389/fevo.2020.00183. calibrated trees are challenging to estimate for many extinct groups of species due to the incompleteness of the rock and fossil records. Additionally, the precise age of a sample is typically not known as it may have occurred at any time during the time interval spanned by the rock layer. Bayesian phylogenetic approaches provide a coherent framework for incorporating multiple sources of evidence and uncertainty. In this study, we simulate datasets with characteristics typical of Palaeozoic marine invertebrates, in terms of character and taxon sampling. We use these datasets to examine the impact of different age handling methods on estimated topologies and divergence times obtained using the fossilized birth-death process. Our results reiterate the importance of modeling fossil age uncertainty, although we find that the relative impact of fossil age uncertainty depends on both fossil taxon sampling and character sampling. Sampling the fossil ages as part of the inference gives topology and divergence time estimates that are as good as those obtained by fixing ages to the truth, whereas fixing fossil ages to incorrect values results in higher error and lower coverage. The relative effect increases with increased fossil and character sampling. Modeling fossil age uncertainty is thus critical, as fixing incorrect fossil ages will negate the benefits of improved fossil and character sampling.Barras, C., 2020. Controversial cave discoveries suggest humans reached Americas much earlier than thought. Nature 583, 670-671. say stone artefacts point to occupation more than 30,000 years ago — but not everyone is convinced. Archaeologists excavating a cave in the mountains of central Mexico have unearthed evidence that people occupied the area more than 30,000 years ago — suggesting that humans arrived in North America at least 15,000 years earlier than thought.The discovery, which includes hundreds of ancient stone tools, is backed up by a fresh statistical analysis that incorporates data from other sites. But the conclusion has stirred controversy among some researchers.“When I see a claim being made that is so dramatic, then the evidence has to be there to substantiate the claim,” says archaeologist Kurt Rademaker at Michigan State University in East Lansing. The first humans in the Americas came from East Asia, but when they began to arrive is hotly debated. Some researchers think that it could have been as early as 130,000 years ago, although most of the archaeological evidence supporting this theory is disputed. For instance, some of the stone artefacts are so simple that sceptics say they were probably produced by natural geological processes rather than by people. The mainstream view is that the peopling of the Americas began about 15,000 or 16,000 years ago — based on genetic evidence and artefacts found at sites including the 14,000-year-old Monte Verde II in Chile.The latest discoveries, published on 22 July in Nature1, question that consensus. Since 2012, a team led by Ciprian Ardelean at the Autonomous University of Zacatecas in Mexico has been excavating Chiquihuite Cave, which is 2,740 metres above sea level in the country’s Astillero Mountains. The researchers found almost 2,000 stone tools, 239 of which were embedded in layers of gravel that have been carbon dated to between 25,000 and 32,000 years old.There are so few of these oldest tools that Ardelean thinks the site was visited only occasionally, perhaps used as a refuge every few decades, during particularly severe winters. At the height of the last ice age, 26,000 years ago, North America would have been a dangerous place. “There must have been horrible storms, hail, snow,” he says. He adds that the Chiquihuite Cave is well insulated and could have provided shelter to any humans who were around to witness the blizzards.Troublesome dataThe team makes a good case for ancient human occupation, says Fran?ois Lano?, an archaeologist and anthropologist at the University of Arizona in Tucson. But he adds that data from caves are “notoriously troublesome” to interpret. Stone tools might have been shifted into deeper layers by geological or biological activity — perhaps moved by burrowing animals — making them seem older than they really are.That’s assuming they really are stone tools. “If an artefact is a stone tool, you see numerous chips removed from the edge,” says Rademaker. He sees no clear evidence of this in the images in the paper — a point echoed by archaeologist Ben Potter at Liaocheng University in China.Ardelean admits that some of the tools might have shifted into lower layers, although he says the 239 oldest tools lie beneath an impenetrable layer of mud formed during the height of the last ice age, so they must be at least that old. He insists they are tools — in fact, he thinks some have telltale marks suggesting that they were made by novices learning from experts. “Somebody was teaching somebody else at this site,” he says.Aside from the stone tools, the team found relatively little evidence of human presence. Geneticists led by Eske Willerslev at the University of Copenhagen searched for ancient human DNA in the cave dirt, but with no luck. “Of course, I was disappointed,” says Ardelean.Early settlersIn a second study, also published in Nature2, two of Ardelean’s co-authors — archaeologists Thomas Higham and Lorena Becerra-Valdivia at the University of Oxford, UK — combined the Chiquihuite Cave evidence with data from 41 other archaeological sites in North America and a region of eastern Siberia and western Alaska called Beringia, and built a statistical model of early human settlement. They concluded that people were present across North America much earlier than the accepted date of 15,000–16,000 years ago.Some archaeologists think that it is time to take these ideas seriously. “The growing body of evidence for people in Beringia before 15,000 years ago renders their appearance in places like Mexico 20,000 or 30,000 years ago less surprising,” says John Hoffecker, an archaeologist at the University of Colorado Boulder.Others disagree. Collins says Becerra-Valdivia and Higham assume that early sites such as Chiquihuite Cave and Bluefish Caves3 in Yukon, Canada, where artefacts have been dated to 24,000 years ago, offer unambiguous evidence of human activity. “This is far from the case,” he says.Becerra-Valdivia accepts that evidence from most sites — with the exception of Monte Verde II — is disputed, but says that the analysis purposely omitted information from the most controversial sites, to make its case stronger.If there were people in North America so early, it’s unclear what happened to them. “There continues to be no convincing genetic evidence of a pre-15,000-years-ago human presence in the Americas,” says geneticist David Reich at Harvard Medical School in Boston, MassachusettsArdelean says there is a simple reason why genetic studies4 suggest that humans spread across the Americas only relatively recently: early groups such as the one he thinks was present at Chiquihuite Cave didn’t survive to contribute to modern gene pools. “I definitely advocate for the idea of lost groups,” he says.Bastviken, D., Nygren, J., Schenk, J., Parellada Massana, R., Duc, N.T., 2020. Technical note: Facilitating the use of low-cost methane (CH4) sensors in flux chambers – calibration, data processing, and an open-source make-it-yourself logger. Biogeosciences 17, 3659-3667. major bottleneck regarding the efforts to better quantify greenhouse gas fluxes, map sources and sinks, and understand flux regulation is the shortage of low-cost and accurate-enough measurement methods. The studies of methane (CH4) – a long-lived greenhouse gas increasing rapidly but irregularly in the atmosphere for unclear reasons, and with poorly understood source–sink attribution – suffer from such method limitations. This study presents new calibration and data processing approaches for use of a low-cost CH4 sensor in flux chambers. Results show that the change in relative CH4 levels can be determined at rather high accuracy in the 2–700?ppm mole fraction range, with modest efforts of collecting reference samples in situ and without continuous access to expensive reference instruments. This opens possibilities for more affordable and time-effective measurements of CH4 in flux chambers. To facilitate such measurements, we also provide a description for building and using an Arduino logger for CH4, carbon dioxide (CO2), relative humidity, and temperature.Baucon, A., Corradini, C., Floris, M., Briguglio, A., Cabella, R., Campomenosi, N., Piazza, M., Corriga, M.G., 2020. Life in near-anoxic conditions: A case study of the ichnology and infaunal ecology of Silurian graptolitic black shales from Sardinia, Italy. Palaeogeography, Palaeoclimatology, Palaeoecology 556, 109889. trace fossil assemblage from the Silurian (Llandovery) black shales of the Genna Muxerru Formation is reported for the first time. The ichnofossil record is abundant, well-preserved and comprises Alcyonidiopsis, Cochlichnus, Phymatoderma, Planolites (large morphotype), Planolites (rough morphotype) and a ‘Small chondritid’. Sedimentological and ichnological evidence indicates that the bioturbated black shales were deposited in outer shelf (or deeper) settings with severe depletion in oxygen. The seafloor provided a high food supply for the infauna. The palaeoenvironment of the Genna Muxerru Formation is an ancient analogue of modern oxygen-minimum zones. Burrow fills are apparently massive in macroscopic view, whereas observations under the petrographic and stereoscopic microscope show that a lifestyle dominated, i.e. that of pellet-filling sediment-feeders. As such, the Genna Muxerru Formation provides not only a new ethologic reference for low-oxygen settings but also a methodological benchmark for ichnological analysis of black shales. Bioturbation in black shales may be commoner than expected but its recognition requires microscopic observation.Bechtel, A., Widera, M., Lücke, A., Gro?, D., Woszczyk, M., 2020. Petrological and geochemical characteristics of xylites and associated lipids from the First Lusatian lignite seam (Konin Basin, Poland): Implications for floral sources, decomposition and environmental conditions. Organic Geochemistry 147, 104052. pieces of fossil wood fragments (xylites) were collected from the middle Miocene First Lusatian lignite seam at the Adamów, Jó?win IIB and Tomis?awice opencast mines and are characterized by maceral variety, cellulose contents and their molecular and isotopic composition. Biomarker composition of xylites and δ13C of their total organic matter, lipids and cellulose are used to provide insights into woody plant community and the effects of wood decomposition.The investigated xylites represent fragments of fossil wood from conifers, most likely species of Cupressaceae, indicated by terpenoid biomarkers characteristic for conifers and by the δ13C values of the extracted cellulose. This conclusion is confirmed by paleobotanical data highlighting Taxodium and Nyssa as the main elements of the wet forest swamps. Due to the wet swamp habitat and the higher-decay resistance exclusively wood fragments of conifers are found in the lignite seam. Minor abundances of angiosperm-derived triterpenoids in the xylites are explained by impurities from inherent detritic lignite.The xylites are characterized by minor to moderate extents of gelification, but elevated to high cellulose decomposition. The relationship between δ13C values of xylites and their cellulose contents reflects wood decomposition removing preferentially the 13C-enriched compounds, but decomposition did not affect the δ13C of cellulose. Despite of similar δ13C of xylites and detritic lignite, differences in isotopic composition of hopanoids argue for slightly different microbial communities involved in the decomposition of the respective OM. Thus, we conclude that wood decomposition proceeded in a freshwater environment under acidic conditions by fungi and bacteria.Variations in water availability during growth periods of the conifers are suggested as the most probable cause for the observed minor variations in isotopic composition of plant lipids. The positive relationship found between δ2H and δ13C of plant biomarkers, and cellulose of xylites can be explained by the ability of vascular plants to minimize evapotranspiration during dryer phases resulting in plant OM enriched in 13C and 2H. The significant differences in δ2H between diterpenoids of different structural types and n-alkanes are most likely caused by differences in isotopic fractionation during lipid biosynthesis.Bédir, M., Soltani, A., Mohamed, A.B., Arbi, A., Saidi, M., 2020. Cretaceous petroleum system modeling of Kairouan Basin in eastern Tunisia. Arabian Journal of Geosciences 13, 683. Cretaceous deposits in central eastern Tunisia represent a potential proven source rocks from Cenomanian–Albian Fahdene and Turonian Bahloul Formations and reservoir rocks of Turonian Bireno, Douleb, and Campanian–Maastrichtian Abiod Formations. The latter form the main oil and gas field systems in onshore and offshore central eastern Tunisia. Seismic tectonics and seismic stratigraphy based on 2D seismic analyses calibrated to the petroleum well’s wireline logging led to the identification of source rock and reservoir sequence distribution between high platforms and subsiding basin areas. This structuring has been created by inherited deep-seated transtensive and transpressive flower faults (Kairouan-Sousse, Hdadja, El Jem, Mahdia, etc.) that are intruded by Triassic halokinetic evaporites. Geochemical analyses and modeling of the well and pseudo-well deposits using BasinMod 1D software from a plate river had permitted to differentiate kitchen areas, within the basin areas, that have high maturity level (late oil to gas generation phase) of Fahdene and Bahloul Cretaceous source rocks. The neighboring high flank structures might constitute good traps to accumulate expelled materials. The large-scale fault system and the dense fracture network related to the Kairouan Basin borders represent a preferential pathway for fluids to reach updip flank reservoir units. The geochemistry modeling was performed in order to characterize the maturity, generation, and expulsion timing of hydrocarbons. In addition, this study highlights the great gas shale potential steel remaining in the subsiding basin kitchens.Beeby, M., Ferreira, J.L., Tripp, P., Albers, S.-V., Mitchell, D.R., 2020. Propulsive nanomachines: the convergent evolution of archaella, flagella and cilia. FEMS Microbiology Reviews 44, 253-304. the repeated convergent evolution of flight and vision in large eukaryotes, propulsive swimming motility has evolved independently in microbes in each of the three domains of life. Filamentous appendages – archaella in Archaea, flagella in Bacteria and cilia in Eukaryotes – wave, whip or rotate to propel microbes, overcoming diffusion and enabling colonization of new environments. The implementations of the three propulsive nanomachines are distinct, however: archaella and flagella rotate, while cilia beat or wave; flagella and cilia assemble at their tips, while archaella assemble at their base; archaella and cilia use ATP for motility, while flagella use ion-motive force. These underlying differences reflect the tinkering required to evolve a molecular machine, in which pre-existing machines in the appropriate contexts were iteratively co-opted for new functions and whose origins are reflected in their resultant mechanisms. Contemporary homologies suggest that archaella evolved from a non-rotary pilus, flagella from a non-rotary appendage or secretion system, and cilia from a passive sensory structure. Here, we review the structure, assembly, mechanism and homologies of the three distinct solutions as a foundation to better understand how propulsive nanomachines evolved three times independently and to highlight principles of molecular evolution.Beerling, D.J., Kantzas, E.P., Lomas, M.R., Wade, P., Eufrasio, R.M., Renforth, P., Sarkar, B., Andrews, M.G., James, R.H., Pearce, C.R., Mercure, J.-F., Pollitt, H., Holden, P.B., Edwards, N.R., Khanna, M., Koh, L., Quegan, S., Pidgeon, N.F., Janssens, I.A., Hansen, J., Banwart, S.A., 2020. Potential for large-scale CO2 removal via enhanced rock weathering with croplands. Nature 583, 242-248. silicate rock weathering (ERW), deployable with croplands, has potential use for atmospheric carbon dioxide (CO2) removal (CDR), which is now necessary to mitigate anthropogenic climate change. ERW also has possible co-benefits for improved food and soil security, and reduced ocean acidification. Here we use an integrated performance modelling approach to make an initial techno-economic assessment for 2050, quantifying how CDR potential and costs vary among nations in relation to business-as-usual energy policies and policies consistent with limiting future warming to 2 degrees Celsius. China, India, the USA and Brazil have great potential to help achieve average global CDR goals of 0.5 to 2 gigatonnes of carbon dioxide (CO2) per year with extraction costs of approximately US$80–180 per tonne of CO2. These goals and costs are robust, regardless of future energy policies. Deployment within existing croplands offers opportunities to align agriculture and climate policy. However, success will depend upon overcoming political and social inertia to develop regulatory and incentive frameworks. We discuss the challenges and opportunities of ERW deployment, including the potential for excess industrial silicate materials (basalt mine overburden, concrete, and iron and steel slag) to obviate the need for new mining, as well as uncertainties in soil weathering rates and land–ocean transfer of weathered products.Berg, G., Rybakova, D., Fischer, D., Cernava, T., Vergès, M.-C.C., Charles, T., Chen, X., Cocolin, L., Eversole, K., Corral, G.H., Kazou, M., Kinkel, L., Lange, L., Lima, N., Loy, A., Macklin, J.A., Maguin, E., Mauchline, T., McClure, R., Mitter, B., Ryan, M., Sarand, I., Smidt, H., Schelkle, B., Roume, H., Kiran, G.S., Selvin, J., Souza, R.S.C.d., van Overbeek, L., Singh, B.K., Wagner, M., Walsh, A., Sessitsch, A., Schloter, M., 2020. Microbiome definition re-visited: old concepts and new challenges. Microbiome 8, 103. field of microbiome research has evolved rapidly over the past few decades and has become a topic of great scientific and public interest. As a result of this rapid growth in interest covering different fields, we are lacking a clear commonly agreed definition of the term “microbiome.” Moreover, a consensus on best practices in microbiome research is missing. Recently, a panel of international experts discussed the current gaps in the frame of the European-funded MicrobiomeSupport project. The meeting brought together about 40 leaders from diverse microbiome areas, while more than a hundred experts from all over the world took part in an online survey accompanying the workshop. This article excerpts the outcomes of the workshop and the corresponding online survey embedded in a short historical introduction and future outlook. We propose a definition of microbiome based on the compact, clear, and comprehensive description of the term provided by Whipps et al. in 1988, amended with a set of novel recommendations considering the latest technological developments and research findings. We clearly separate the terms microbiome and microbiota and provide a comprehensive discussion considering the composition of microbiota, the heterogeneity and dynamics of microbiomes in time and space, the stability and resilience of microbial networks, the definition of core microbiomes, and functionally relevant keystone species as well as co-evolutionary principles of microbe-host and inter-species interactions within the microbiome. These broad definitions together with the suggested unifying concepts will help to improve standardization of microbiome studies in the future, and could be the starting point for an integrated assessment of data resulting in a more rapid transfer of knowledge from basic science into practice. Furthermore, microbiome standards are important for solving new challenges associated with anthropogenic-driven changes in the field of planetary health, for which the understanding of microbiomes might play a key role.Beunon, H., Mattielli, N., Doucet, L.S., Moine, B., Debret, B., 2020. Mantle heterogeneity through Zn systematics in oceanic basalts: Evidence for a deep carbon cycling. Earth-Science Reviews 205, 103174. at convergent margins introduces a range of sedimentary and crustal materials into the mantle, providing the most dominant form of heterogeneity in the source of oceanic basalts. Yet, the relationship between geochemical variability and lithologic heterogeneities in the Earth's mantle remains controversial. In this paper, we comprehensively review Zn, δ66Zn and Sr-Nd isotope systematics in near-primary basalts erupted at mid-ocean ridges (MORB) and ocean islands (OIB) to help constrain the nature and proportion of the carbon (C) bearing slab-derived component in their mantle sources. We show that Zn elemental and isotopic composition of oceanic basalts differs according to their tectonic settings, increasing from MORB (Zn = 62 ± 10 to 73 ± 11 ppm; δ66Zn = +0.24 ± 0.01 to +0.31 ± 0.02‰) to OIB (Zn = 74 ± 9 to 124 ± 7 ppm; δ66Zn = +0.21 ± 0.07 to +0.40 ± 0.04‰). Unlike MORB, the high Zn and δ66Zn recorded in OIB cannot be explained by partial melting of a fertile peridotite mantle source only. Importantly, global correlations between Zn content and Sr-Nd isotopes in oceanic basalts suggest that the Zn enrichment in OIB is inherited from a recycled component in their mantle source rather than melting processes. We demonstrate that involvement of neither typical MORB-like oceanic crust nor subducted sediments can achieve the whole range of Zn composition in OIB. Instead, addition of ≤6% C-bearing oceanic crust to a fertile peridotite mantle fully resolves the Zn heterogeneity of OIB, both in terms of magnitude of Zn enrichment and global trends with Sr-Nd isotopes. Such scenario is corroborated by the elevated δ66Zn of OIB relative to MORB and mantle peridotites, reflecting the contribution of isotopically heavy C-bearing phases (δ66Zn = +0.91 ± 0.24‰) to the mantle source (δ66Zn = +0.16 ± 0.06‰). Our study thus emphasizes the use of Zn and δ66Zn systematics to track the nature and origin of mantle carbon, highlighting the role of subduction in the deep carbon cycle. Finally, the positive correlation between Zn content and temperature of magma generation of oceanic basalts suggests that hotter mantle plumes are more likely to carry a higher proportion of dense C-bearing eclogite. Zinc systematics therefore may provide evidence that the presence of heterogeneous domains in the source of OIB is, at least partly, linked to plume thermal buoyancy, bringing new insights into mantle dynamics.Bhinderwala, F., Evans, P., Jones, K., Laws, B.R., Smith, T.G., Morton, M., Powers, R., 2020. Phosphorus NMR and its application to metabolomics. Analytical Chemistry 92, 9536-9545. isotopes are routinely employed by NMR metabolomics to highlight specific metabolic processes and to monitor pathway flux. 13C-carbon and 15N-nitrogen labeled nutrients are convenient sources of isotope tracers and are commonly added as supplements to a variety of biological systems ranging from cell cultures to animal models. Unlike 13C and 15N, 31P-phosphorus is a naturally abundant and NMR active isotope that does not require an external supplemental source. To date, 31P NMR has seen limited usage in metabolomics because of a lack of reference spectra, difficulties in sample preparation, and an absence of two-dimensional (2D) NMR experiments, but 31P NMR has the potential of expanding the coverage of the metabolome by detecting phosphorus-containing metabolites. Phosphorylated metabolites regulate key cellular processes, serve as a surrogate for intracellular pH conditions, and provide a measure of a cell’s metabolic energy and redox state, among other processes. Thus, incorporating 31P NMR into a metabolomics investigation will enable the detection of these key cellular processes. To facilitate the application of 31P NMR in metabolomics, we present a unified protocol that allows for the simultaneous and efficient detection of 1H-, 13C-, 15N-, and 31P-labeled metabolites. The protocol includes the application of a 2D 1H–31P HSQC-TOCSY experiment to detect 31P-labeled metabolites from heterogeneous biological mixtures, methods for sample preparation to detect 1H-, 13C-, 15N-, and 31P-labeled metabolites from a single NMR sample, and a data set of one-dimensional (1D) 31P NMR and 2D 1H–31P HSQC-TOCSY spectra of 38 common phosphorus-containing metabolites to assist in metabolite assignments.Bian, H., Xia, Y., Lu, C., Qin, X., Meng, Q., Lu, H., 2020. Pore structure fractal characterization and permeability simulation of natural gas hydrate reservoir based on CT images. Geofluids 2020, 6934691. gas-water two-phase seepage process is complex during the depressurization process of natural gas hydrate in a clayey silt reservoir in the South China Sea, the transport mechanism of which has not been clarified as it is affected by the pore structure. In this study, we select six clayey silt samples formed after the dissociation of natural gas hydrate in the South China Sea, employing CT scanning technology to observe the pore structure of clayey silt porous media directly. The original CT scanning images are further processed to get the binarized images of the samples, which can be used for simulation of the porosity and absolute permeability. Based on the fractal geometry theory, pore structures of the samples are quantitatively characterized from the aspect of pore distribution, heterogeneity, and anisotropy (represented by three main fractal geometric parameters: fractal dimension, lacunarity, and succolarity, respectively). As a comparison, the binarized CT images of two conventional sandstone cores are simulated with the same parameters. The results show that the correlation between porosity and permeability of the hydrate samples is poor, while there is a strong correlation among the succolarity and the permeability. Fractal dimension (represents complexity) of clayey silt samples is higher compared with conventional sandstone cores. Lacunarity explains the difference in permeability among samples from the perspective of pore throat diameter and connectivity. Succolarity indicates the extent to which the fluid in the pore is permeable, which can be used to characterize the anisotropy of pore structures. Therefore, these three fractal parameters clarify the relationship between the microstructure and macroscopic physical properties of clayey silt porous media.Bierson, C.J., Nimmo, F., Stern, S.A., 2020. Evidence for a hot start and early ocean formation on Pluto. Nature Geoscience 13, 468-472. is thought to possess a present-day ocean beneath a thick ice shell. It has generally been assumed that Pluto accreted from cold material and then later developed its ocean due to warming from radioactive decay; in this ‘cold start’ scenario, the ice shell would have experienced early compression and more recent extension. Here we compare thermal model simulations with geological observations from the New Horizons mission to suggest that Pluto was instead relatively hot when it formed, with an early subsurface ocean. Such a ‘hot start’ Pluto produces an early, rapid phase of extension, followed by a more prolonged extensional phase, which totals ~0.5% linear strain over the last 3.5 Gyr. The amount of second-phase extension is consistent with that inferred from extensional faults on Pluto; we suggest that an enigmatic ridge–trough system recently identified on Pluto is indicative of early extensional tectonics. A hot initial start can be achieved with the gravitational energy released during accretion if the final stage of Pluto’s accretion is rapid (<30 kyr). A fast final stage of growth is in agreement with models of the formation of Kuiper belt objects via gravitational collapse followed by pebble accretion, and implies that early oceans may have been common in the interiors of large Kuiper belt objects.Billings, S.A., de Souza, L.F.T., 2020. Earth’s soil harbours ancient carbon. Nature Geoscience 13, 527-528. carbon in the top metre of Earth’s soils is far older than previously thought, averaging 4,800 years old. These radiocarbon-derived age estimates require us to recalibrate our expectations of ecosystem gains and losses of carbon.Earth’s soils serve as an immense carbon reservoir, storing more carbon than the atmosphere and vegetation combined. Understanding how organic carbon within soil is both gained and lost is critical for the accurate projection of future climate. Gauging how long carbon has been retained by soil can reveal if it cycles on decadal timescales or over centuries or millennia, providing important constraints on carbon retention and loss in soils1. Writing in Nature Geoscience, Shi et al.2 analyse a recently published database3 of radiocarbon signatures from thousands of soil profiles around the world and reveal an average age of Earth’s soil carbon that is older than previously thought. Their findings suggest that model projections of soil potential to sequester carbon in the twenty-first century are too anic carbon in soils originates from plants, which remove atmospheric CO2 via photosynthesis and, upon death, can become part of the soil. Soil microorganisms can oxidize many of these plant-derived organic carbon compounds to fuel their metabolisms, generating CO2 in the process. Much of this CO2 is returned to the atmosphere. Understanding whether soils are a net source of CO2 to the atmosphere or a net sink, and over what timescales these net fluxes vary, is a critical part of understanding Earth’s future carbon balance, and thus Earth’s future climate. One important factor in determining the extent to which soils can retain organic carbon over timescales relevant to anthropogenic climate change, and the carbon cycling processes that govern such sequestration, is the average age of a given pool of soil carbon. Carbon is found as a variety of isotopes, one of which, 14C, is radioactive and decays over time. As a result, pools of soil organic carbon generated before nuclear testing released large amounts of 14C into the atmosphere exhibit increasing 14C depletion as they age — they possess increasingly negative Δ14C signatures.Shi and colleagues use a global database of Δ14C signatures3 from over 2,500 soil profiles (Fig. 1) to demonstrate at a global scale what place-based research has demonstrated in myriad studies4: increasingly negative Δ14C signatures with depth. This phenomenon is interpreted as increasing mean soil carbon age with depth. One of the more startling advances their work demonstrates is that the global mean age of soil organic carbon for the top 1 m of soil is 4,830 ± 1,730 years. This value reflects a mean age of 1,390 ± 310 years in the surficial top 30 cm of soils and a far older estimate of 8,280 ± 2,820 years in subsurface soils. These estimates contrast with the two global land surface models that Shi et al. explored, both of which suggest younger mean carbon ages and thus more rapid turnover of soil carbon. The work of Shi et al. therefore challenges the commonly held perception that relatively little soil carbon is retained by soils for thousands of years.Intriguingly, Shi et al. find that the drivers of soil Δ14C appear to vary with depth and region. Carbon in surface soils of warmer regions appears younger than the equivalent depth in cooler regions, as might be expected given the important role of temperature on whole-ecosystem carbon cycling5,6. However, in deeper soils, depth interval, mean annual precipitation, and clay content are also drivers of inferred mean carbon age. This highlights the role of moisture in transporting surficial carbon into deeper soil horizons, and the importance of soil clay content in the stabilization and persistence of deep soil carbon. Extremely old mean soil carbon ages in deep, tropical soils likely reflect the importance of additional, abiotic mechanisms of carbon stabilization often present in acidic conditions7.The implications of the study are further highlighted when we consider potential reasons for the differences between their mean soil carbon ages and those estimated by land surface models. Models that overestimate input rates of carbon to soil or underestimate loss rates of recently added carbon would, all else being equal, generate soil carbon ages that are too young and soil carbon turnover rates that are too high. Likewise, models that overestimate the loss of older soil carbon generate qualitatively similar results. Regardless of the sources of the discrepancy between model estimates and the study of Shi et al., these findings require us to recalibrate our estimates of the capacity for soils to sequester carbon.The depth-dependence of soil Δ14C signatures suggests its potential as a tool to investigate many open questions in soils-focused ecosystem science. Can we use radiocarbon-derived inferences about soil carbon turnover and CO2 production, which can promote pedogenesis8, to better understand trajectories of soil development? Will the intensity and depth of downward clay movement through soil9, a process that offers protection to carbon, change with precipitation regime? Can we use today’s mean soil carbon ages to project future soil carbon dynamics of specific biomes as they respond to altered precipitation and temperature in the Anthropocene? Will soil Δ14C signatures increasingly signal the influence of climate change on microbially mediated losses of deep carbon pools, or will human modifications of land cover and associated changes in rooting depths prove dominant drivers of subsurface carbon turnover? How do the responses to these questions change if we go deeper than 1 m, where yet more soil carbon is stored? These questions represent but a subset of the compelling investigations this work prompts.Shi and colleagues harness a global database to argue that Earth’s soils will accumulate less carbon this century than models project. This is a critical conclusion as the Anthropocene unfolds and perturbations to Earth’s atmosphere, hydrosphere, lithosphere, and biosphere expand in intensity and scope. The imperative to understand the biotic and abiotic interactions that govern carbon dynamics in soil — where these spheres intersect to support life — has never been stronger.References1. Trumbore, S. Annu. Rev. Earth Planet. Sci. 37, 47–66 (2009).2. Shi, Z. et al. Nat. Geosci. (2020).3. Lawrence, C. R. et al. Earth Syst. Sci. Data 12, 61–76 (2020).4. He, Y. et al. Science 353, 1419–1424 (2016).5. Giardina, C. P., Litton, C. M., Crow, S. E. & Asner, G. P. Nat. Clim. Change 4, 822–827 (2014).6. Ziegler, S. E. et al. Front. Earth Sci. 5, 2 (2017).7. Kramer, M. G. & Chadwick, O. A. Nat. Clim. Change 8, 1104–1108 (2018).8. Richter, D. deB. & Billings, S. A. New Phytol. 206, 900–912 (2015).9. Calabrese, S., Richter, D. D. & Porporato, A. Geophys. Res. Lett. 45, 7588–7595 (2018).Blevins, M.S., James, V.K., Herrera, C.M., Purcell, A.B., Trent, M.S., Brodbelt, J.S., 2020. Unsaturation elements and other modifications of phospholipids in bacteria: New insight from ultraviolet photodissociation mass spectrometry. Analytical Chemistry 92, 9146-9155. (GPLs), one of the main components of bacterial cell membranes, exhibit high levels of structural complexity that are directly correlated with biophysical membrane properties such as permeability and fluidity. This structural complexity arises from the substantial variability in the individual GPL structural components such as the acyl chain length and headgroup type and is further amplified by the presence of modifications such as double bonds and cyclopropane rings. Here we use liquid chromatography coupled to high-resolution and high-mass-accuracy ultraviolet photodissociation mass spectrometry for the most in-depth study of bacterial GPL modifications to date. In doing so, we unravel a diverse array of unexplored GPL modifications, ranging from acyl chain hydroxyl groups to novel headgroup structures. Along with characterizing these modifications, we elucidate general trends in bacterial GPL unsaturation elements and thus aim to decipher some of the biochemical pathways of unsaturation incorporation in bacterial GPLs. Finally, we discover aminoacyl-PGs not only in Gram-positive bacteria but also in Gram-negative C. jejuni, advancing our knowledge of the methods of surface charge modulation that Gram-negative organisms may adopt for antibiotic resistance.Blyakharchuk, T., Udachin, V., Li, H.-C., Kang, S.-C., 2020. AMS 14C dating problem and high-resolution geochemical record in Manzherok Lake sediment core from Siberia: Climatic and environmental reconstruction for Northwest Altai over the past 1,500 years. Frontiers in Earth Science 8, 206. doi: 10.3389/feart.2020.00206. study presents high-resolution multi-proxy biological and geochemical records in an 82-cm sediment core from Manzherok Lake located in a forest–steppe zone on the western piedmonts of Altai Mountain, Russia. Based on 210Pb dating and 48 accelerator mass spectrometry 14C dates as well as pollen data and geochemical proxies, detailed lake history and local climatic changes over 1,500 years are obtained. Prior to the Medieval Warm Period (MWP), the lake had high productivity under stable moderately wet and warm conditions. During 1,150–1,070 year BP, strong surface runoff led to a high detritus input and an increasing lake level, reflecting the onset of MWP. The lake was deep and fresh under the warm and wet conditions of MWP (1,070–850 year BP). In this interval, more aquatic algae and submerged plants on the lake bottom were generated, which would use dissolved CO2 partially decomposed from organic matters in the deeper sediment layers. Consequently, many acid–base–acid-treated samples contain old carbon influence on their 14C dates. This calls for attention on the chronological construction of lake sediments. During 850–700 year BP, the lake level started to drop with reduced sediment load under cooling and drying conditions. Low sedimentation and lake productivity occurred due to cold and dry climates during 700–500 years BP. Very low sedimentation and hiatus were attributed to ice cover and weak water input between 500 and 50 years BP, corresponding to cold and dry Little Ice Age. Manzherok Lake has recovered productivity and deposition during the current warming century. Change in the total solar irradiance (TSI) is an important factor to influence the climate in the Altai Mountains. With decreased TSI, the Siberian High became strong, which led to the Westerly and the polar front being pushed away from this region, resulting in arid climates. The situation was reversed vice versa.Bond, D.P.G., Grasby, S.E., 2020. Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation. Geology 48, 777-781. Ordovician saw major diversification in marine life abruptly terminated by the Late Ordovician mass extinction (LOME). Around 85% of species were eliminated in two pulses 1 m.y. apart. The first pulse, in the basal Hirnantian, has been linked to cooling and Gondwanan glaciation. The second pulse, later in the Hirnantian, is attributed to warming and anoxia. Previously reported mercury (Hg) spikes in Nevada (USA), South China, and Poland implicate an unknown large igneous province (LIP) in the crisis, but the timing of Hg loading has led to different interpretations of the LIP-extinction scenario in which volcanism causes cooling, warming, or both. We report close correspondence between Hg, Mo, and U anomalies, declines in enrichment factors of productivity proxies, and the two LOME pulses at the Ordovician-Silurian boundary stratotype (Dob’s Linn, Scotland). These support an extinction scenario in which volcanogenic greenhouse gases caused warming around the Katian-Hirnantian boundary that led to expansion of a preexisting deepwater oxygen minimum zone, productivity collapse, and the first LOME pulse. Renewed volcanism in the Hirnantian stimulated further warming and anoxia and the second LOME pulse. Rather than being the odd-one-out of the “Big Five” extinctions with origins in cooling, the LOME is similar to the others in being caused by volcanism, warming, and anoxia.Bond, D.P.G., Grasby, S.E., 2020. Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation: REPLY. Geology 48, e510. to Comment by: Mitchell, C.E., Melchin, M.J., 2020. Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation: COMMENT. Geology 48, e509-e509.Original Article: Bond, D.P.G., Grasby, S.E., 2020. Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation. Geology 48, 777-781.Mitchell and Melchin (2020) are right to highlight that problems remain in global correlations of the Late Ordovician mass extinction (LOME)—and of course, the chronology at Dob’s Linn requires improved biostratigraphy. However, their assertion that we (Bond and Grasby, 2020) placed the base of the Hirnantian Stage too high at Dob’s Linn has little bearing on the extinction timing and our observed geochemical changes, and therefore on our conclusion that the two pulses of the were driven by volcanogenic warming, anoxia and productivity collapse. Here we respond to each of the four main criticisms: (1) Our “biozonation for the Dob’s Linn succession does not include significant revisions published since Williams (1988)”. Though we employed revised names for the Katian through Rhuddanian graptolite Zones, we accept that if the Metabolograptus persculptus is found within the Extraordinarius Band at Dob’s Linn, then that level must date to the eponymous zone. Although Melchin et al. (2003) state “At Dob’s Linn it has recently been discovered that Normalograptus persculptus occurs in what has previously been named the Extraordinarius Band”, and Melchin et al. (2013) mark the Extraordinarius Band as the first appearance datum (FAD) of this species, neither provide a citation for this discovery. This must be clarified if the zonal boundary is to be moved at Dob’s Linn.(2) “…it is likely that the Hirnantian Age began at Dob’s Linn shortly after deposition of Anceps Band D”. We agree that there is a high degree of uncertainty in establishing the base of the Hirnantian at Dob’s Linn. If the basal Hirnantian graptolite species M. extraordinarius first occurs in Anceps Band E, then we should revise our placement of the Katian/ Hirnantian boundary to ~0.4 m lower in the stratigraphy. To suggest that the Hirnantian began at Dob’s Linn shortly after deposition of Anceps Band D, based on the sedimentological analysis of Armstrong and Coe (1997), not only highlights the problems of global correlation that we are happy to acknowledge, but is also a circular argument biased by a glaciation-driven extinction model. The M. extraordinarius Zone atDob’s Linn should begin at the level of that species’ FAD, not 1.5 m lower, at Anceps Band D. (3) Challenging our attempt to overturn long-held views on the glaciation-extinction hypothesis, Mitchell and Melchin state that “sedimentological analysis of the Dob’s Linn succession indicates that the Late Ordovician glacial maximum commenced immediately following deposition of Anceps Band D (Armstrong and Coe, 1997)”. While they interpret their turbidite data in the context of a glaciation-extinction framework, Armstrong and Coe (1997) do not show any direct evidence for glaciation. If it is the case that the glacial maximum occurred around the level of Anceps Band D (in accordance with Finnegan et al.’s [2011] oxygen isotope record), this confirms that the first pulse of extinction, culminating in the Extraordinarius Band, occurred during a phase of warming (i.e., Armstrong and Coe’s [1997] interglacial interval).4) Finally, Mitchell and Melchin state “the LOME was a protracted turnover event that included considerable species evolution during the glacial interval rather than a flanking pair of abrupt extinctions” and that extinctions were “long-lived and regionally diachronous”. It is not inconceivable that extinctions were regionally diachronous, although the scarcity of detailed global paleontological records make their precise timing difficult to resolve. Two main pulses of the LOME did flank a cooling (possibly glacial) interval that saw radiations. We do not question this phase of evolution. However, the local record points to abrupt extinction pulses that correlate with changes in our geochemical proxies, separated by perhaps 1 m.y. Even with shuffling of biostratigraphic boundaries, these pulses occurred on timescales more consistent with abrupt large igneous province (LIP) eruptions than with longer-term waxing and waning of ice sheets. Mitchell and Melchin also suggest that “brachiopod faunal turnover during the LOME also was a long-term process”, but Wang et al. (2019) reinterpret the crisis as a “single-pulse, rapid event” (p. 15) at the level of the first LOME pulse. Rasmussen et al.(2019) suggest that biodiversity began to fall within the Katian, and— somewhat ironically in this context—that LIP volcanism and global warming manifested as, e.g., the Boda Event (Fortey and Cocks, 2005) should also “be included in the crisis interval of the end Ordovician mass extinctions” (Rasmussen et al., 2019, p. 7209).In summary, we completely agree with Mitchell and Melchin in that the LOME is fraught with uncertainties of poor dating, poor correlation, and poorly defined paleontological records. We acknowledge that the two main extinction pulses occurred during an interval of more protracted species loss. This observation does not nullify our findings that the main extinction pulses at Dob’s Linn—around theExtraordinarius Band and the base of the Birkhill Shale—can be linked to volcanism, warming, and anoxia. The long recovery in the post-LIP Silurian world has similarities with the prolonged Early Triassicrecovery following the End Permian Extinction, and this might provide insight into the background loss of diversity. The Late Ordovician events have been too often viewed through the biased glasses of the prevailing concept of cooling-driven extinction; we believe that this should be reassessed in the context of warming and anoxia. We thank Mitchell and Melchin for pointing out the ongoing needto further refine our understanding of extinction processes and the role of LIP eruptions in these. Bonnand, P., Lalonde, S.V., Boyet, M., Heubeck, C., Homann, M., Nonnotte, P., Foster, I., Konhauser, K.O., K?hler, I., 2020. Post-depositional REE mobility in a Paleoarchean banded iron formation revealed by La-Ce geochronology: A cautionary tale for signals of ancient oxygenation. Earth and Planetary Science Letters 547, 116452. banded iron formations (BIF) are chemical sedimentary deposits whose trace element signatures have been widely used to interrogate the chemical composition and redox state of ancient seawater. Here we investigated trace element signatures in BIF of the 3.22 Ga Moodies Group, Barberton Greenstone Belt (South Africa), which are interbedded with near-shore siliciclastic sedimentary rocks and represent one of the oldest known shallow-water occurrences of BIF. Unusual rare earth element (REE) signatures, notably with pronounced negative Ce anomalies in shale-normalized spectra, have been previously reported for chemical sediments of the Moodies Group, which we confirm here through an expanded dataset for Moodies BIF spanning three different localities. We find negative Ce anomalies as low as 0.2 Ce/Ce? that are associated with unusual enrichment of LREE relative to HREE in the sample set. While total REE abundances and certain REE features appear strongly related to the concentration of detrital indicators (e.g., Zr), and are likely primary, other features, notably LREE enrichment, cannot be explained as a primary feature of the sediment. This is better explained by later addition of REE from a LREE-enriched but Ce-depleted fluid that generated the significant negative Ce anomalies observed in surface samples of Moodies Group BIF. This REE addition event influenced both Sm-Nd and La-Ce isotope systematics, the latter yielding an isochron of 60 ± 32 Ma, thus constraining the timing of emplacement of the negative Ce anomalies to the past 100 Ma, possibly upon surface exposure of the Barberton Greenstone Belt to wetter conditions during the Cenozoic. Our findings constitute a cautionary tale in that even the most immobile elemental redox proxies may be more sensitive to post-depositional modification than previously thought, and demonstrate the clear advantage offered by paleoredox proxies coupled to radiometric geochronometers to enable the direct dating of ancient signals of Earth surface oxygenation.Bonto, M., Eftekhari, A.A., M. Nick, H., 2020. Wettability indicator parameter based on the thermodynamic modeling of chalk-oil-brine systems. Energy & Fuels 34, 8018-8036. complex physicochemical interactions in the calcite-brine-crude oil system, triggered by the injection of modified salinity water (MSW) into the reservoir, are modeled by several researchers. However, the proposed models are either not consistent with a wettability alteration mechanism or cannot explain the observed improved oil recovery in chalk. We propose a new methodology denominated “Available Adsorption Sites” (AAS) that assesses the wettability alteration as a combined effect of a chemical and electrostatic contribution. Thus, we describe mathematically the interactions between the polar groups in the oil phase and the chalk by considering analogy with the thermodynamics of adsorption of an ion on a charged surface. The chalk wetting properties depend on the number of sites available for the adsorption of oleic polar groups at the mineral surface and the electrical potential at the rock-brine and brine-oil interfaces. We evaluate how the AAS parameter correlates with the remaining oil saturation from spontaneous imbibition tests on chalk samples. This approach is not only useful for the predictive evaluation of the outcome of MSW in chalk reservoirs but can also be integrated in reactive transport models and assess the flow of organic contaminants (e.g., naphtenic acids) in chalk aquifers. The model can potentially be applied to other carbonates.Booij, K., Chen, S., Trask, J.R., 2020. POCIS calibration for organic compound sampling in small headwater streams. Environmental Toxicology and Chemistry 39, 1334-1342.‐based atrazine sampling rates (R s) obtained by the polar organic chemical integrative sampler (POCIS) method were measured in 9 headwater streams over 3?yr covering 5 to 6 exposure periods of 2 to 3?wk/site/yr. Rates were best in line with the model R s?=?148?mL/d, with a standard deviation of 0.17?log units (factor 1.5). The POCIS canisters reduced mass transfer coefficients of the water boundary layer by a factor of 2 as measured by alabaster dissolution rates. A mechanistic model that accounts for flow and temperature effects yielded a fair estimate of the effective exchange surface area (12.5?±?0.8?cm2). This model could only be tested for higher flow velocities because of uncertainties associated with the measurement of flow velocities <1?cm/s. Pictures of sorbent distributions in POCIS devices showed that the effective exchange surface area varied with time during the exposures. Error analysis indicated that sorbent distributions and chemical analysis were minor error sources. Our main conclusion is that an atrazine sampling rate of 148?mL/d yielded consistent results for all 3?yr across 9 headwater streams. Borisova, L.S., Fomin, A.N., 2020. Transformation of resin–asphaltene components of dispersed organic matter in the meso- and apocatagenesis zone. Petroleum Chemistry 60, 648-658. studying the organic matter (OM) from the Mesozoic deposits of the Tyumen superdeep well (SG-6) as an example, deep zoning in the distribution, composition, and structure of heterocyclic components of the dispersed OM in catagenesis has been revealed. During mesocatagenesis, the composition of asphaltenes undergoes directed changes similar to those found for debitumenized OM. During apocatagenesis, polymerization and condensation of asphaltene molecules and their transition to an insoluble form as a new type of kerogen occur. Their lighter part is involved in structural redistributions inside resins and hydrocarbons (HC) and the formation of gases; there is a relative increase in the concentration of resins and HC (in wt % of residual bitumens). This circumstance should be taken into account when predicting the generation potential of OM and the composition of hydrocarbon fluids formed during catagenesis.Borrego, C., Sabater, S., Proia, L., 2020. Lifestyle preferences drive the structure and diversity of bacterial and archaeal communities in a small riverine reservoir. Scientific Reports 10, 11288. heterogeneity along river networks is interrupted by dams, affecting the transport, processing, and storage of organic matter, as well as the distribution of biota. We here investigated the structure of planktonic (free-living, FL), particle-attached (PA) and sediment-associated (SD) bacterial and archaeal communities within a small reservoir. We combined targeted-amplicon sequencing of bacterial and archaeal 16S rRNA genes in the DNA and RNA community fractions from FL, PA and SD, followed by imputed functional metagenomics, in order to unveil differences in their potential metabolic capabilities within the reservoir (tail, mid, and dam sections) and lifestyles (FL, PA, SD). Both bacterial and archaeal communities were structured according to their life-style preferences rather than to their location in the reservoir. Bacterial communities were richer and more diverse when attached to particles or inhabiting the sediment, while Archaea showed an opposing trend. Differences between PA and FL bacterial communities were consistent at functional level, the PA community showing higher potential capacity to degrade complex carbohydrates, aromatic compounds, and proteinaceous materials. Our results stressed that particle-attached prokaryotes were phylogenetically and metabolically distinct from their free-living counterparts, and that performed as hotspots for organic matter processing within the small reservoir.Bray, E.E., Gruen, M.E., Gnanadesikan, G.E., Horschler, D.J., Levy, K.M., Kennedy, B.S., Hare, B.A., MacLean, E.L., 2020. Cognitive characteristics of 8- to 10-week-old assistance dog puppies. Animal Behaviour 166, 193-206. characterize the early ontogeny of dog cognition, we tested 168 domestic dog, Canis familiaris, puppies (97 females, 71 males; mean age=9.2weeks) in a novel test battery based on previous tasks developed and employed with adolescent and adult dogs. Our sample consisted of Labrador retrievers, golden retrievers and Labrador?× golden retriever crosses from 65 different litters at Canine Companions for Independence, an organization that breeds, trains and places assistance dogs for people with disabilities. Puppies participated in a 3-day cognitive battery that consisted of 14 tasks measuring different cognitive abilities and temperament traits such as executive function (e.g. inhibitory control, reversal learning, working memory), use of social cues, sensory discriminations and reactivity to and recovery from novel situations. At 8–10 weeks of age, and despite minimal experience with humans, puppies reliably used a variety of cooperative-communicative gestures from humans. Puppies accurately remembered the location of hidden food for delays of up to 20s, and succeeded in a variety of visual, olfactory and auditory discrimination problems. They also showed some skill at executive function tasks requiring inhibitory control and reversal learning, although they scored lower on these tasks than is typical in adulthood. Taken together, our results confirm the early emergence of sensitivity to human communication in dogs and contextualize these skills within a broad array of other cognitive abilities measured at the same stage of ontogeny.Brennecke, J.F., Freeman, B., 2020. Reimagining petroleum refining. Science 369, 254-255. separations involve often-complex mixtures of molecules into individual components or mixtures of components with similar properties. Such separations are integral to a variety of technologies, such as the production of liquid fuels and chemicals for transportation as well as everything from plastic bags to sterile medical equipment. On page 310 of this issue, Thompson et al. (1) describe the preparation and characterization of new polymeric membranes for crude oil fractionation, an extremely complex hydrocarbon separation process that is vital to the production of modern fuels and chemicals.The traditional technique for separating crude oil into various fractions involves distillation, a process known since antiquity to separate more volatile from less volatile liquids. However, distillation is extremely energy intensive, relying on repeated evaporation and condensation cycles to achieve separation. Distillation dominates industrial chemical separations and consumes more than a quadrillion British thermal units (Btus) each year in the United States (～1% of total U.S. energy use). Thus, the U.S. National Academies of Sciences, Engineering, and Medicine (NASEM) pinpointed lower-energy alternatives to distillation as a critical need (2).The use of membranes for separation of organic liquid mixtures is an attractive alternative because membranes do not rely on energy-intensive phase changes (such as boiling or condensation) to separate mixtures. The key to the development of new polymeric membranes by Thompson et al. was the synthesis of rigid spirobifluorene aryl diamine polymers (SADP). These polymers are endowed with intrinsic microporosity, which permits high rates of molecule transport. Furthermore, the rigidity enables separation of molecules on the basis of size, shape, and affinity for the membrane material while helping to control swelling of the polymers when in contact with chemically challenging environments. Traditionally, polymers are constructed from organic building blocks, so they absorb these components and swell when in contact with organic mixtures (such as those found in crude oil). Swelling can be highly deleterious to a membrane's ability to separate molecules of similar shape and size. Therefore, although polymeric membranes are widely used for water purification (desalination) and gas separation (air separation, natural gas purification, and hydrogen recovery), they have not been commercialized for large-scale separations of complex organics, such as crude oil (3).Early-stage experiments use dense, thick films and simple binary mixtures of organic liquids to acquire preliminary membrane separation data. This step is important for two reasons: developing structure-property relations to guide future membrane choices and elucidating fundamental details of penetrant transport mechanisms in such materials. However, to be of practical relevance, any interesting membrane material must also be manufactured as a thin-film asymmetric or thin-film composite membrane and be able to separate mixtures of interest. Whereas the former studies are quite common in the membrane literature, the latter thin-film studies are exceptionally rare. Thompson et al. report both types of data, including the successful preparation of thin-film (～0.2 ?m) composite membranes by dip-coating the polymer onto a porous support. The success of these studies demonstrated the practical feasibility of the new approach.Early-stage experiments use dense, thick films and simple binary mixtures of organic liquids to acquire preliminary membrane separation data. This step is important for two reasons: developing structure-property relations to guide future membrane choices and elucidating fundamental details of penetrant transport mechanisms in such materials. However, to be of practical relevance, any interesting membrane material must also be manufactured as a thin-film asymmetric or thin-film composite membrane and be able to separate mixtures of interest. Whereas the former studies are quite common in the membrane literature, the latter thin-film studies are exceptionally rare. Thompson et al. report both types of data, including the successful preparation of thin-film (～0.2 ?m) composite membranes by dip-coating the polymer onto a porous support. The success of these studies demonstrated the practical feasibility of the new approach.References and Notes1. K. A. Thompson et al., Science 369, 310 (2020).2. U.S. NASEM, A Research Agenda for Transforming Separation Science (National Academies Press, 2019).3. R. W. Baker, Membrane Technology and Applications (John Wiley & Sons, ed. 3, 2012), pp. 394–395.4. E. Jones, M. Qadir, M. T. H. van Vliet, V. Smakhtin, S.-M. Kang, Sci. Total Environ. 657, 1343 (2019).5. U.S. Energy Information Administration (EIA), Short-term energy outlook (2020); outlooks/steo/report/global_oil.php6. N. Voutchkov, Desalination 431, 2 (2018).7. J. Kim, K. Park, D. R. Yang, S. Hong, Appl. Energy 254, 113652 (2019).8. S. Zhou, L. Gong, X. Liu, S. Shen, Appl. Therm. Eng. 159, 113759 (2019).Bridgland, D.R., Westaway, R., Hu, Z., 2020. Basin inversion: A worldwide Late Cenozoic phenomenon. Global and Planetary Change 193, 103260. occurrence of endorheic basins on the Tibetan Plateau, both in its Pleistocene history and (fewer in number) at the present day, has been attributed to the ‘basin-and-range’ character of the orogen; the understanding of their conversion to exorheic drainage is key to interpreting the evolution of the Yellow River and other river systems of the plateau. However, such basins also occur in areas of lower altitude and relief and can be observed to have been considerably more common in pre-Quaternary times. In many areas, for example the Mediterranean region, such basins, previously having accumulated stacked sedimentary sequences, typically ‘inverted’ in the late Pliocene or at around the Pliocene–Pleistocene transition, possibly as part of a response to the cooling of global climate and its effect on surface processes. Some basins have inverted later, at around the time of the Mid-Pleistocene Revolution, coinciding with the increased severity of climate resulting from the 100?ka Milankovich cycles that followed that change. The progressive incision into the fills of these inverted sedimentary basins has also been linked to this climatic influence, perhaps taking effect as a result of erosional isostatic uplift, which would have replaced the accumulation-induced subsidence (also isostatic) of the basins. NW Europe, including Britain, had sediment-accumulating basins in the Early Cenozoic; the timing of their inversion is poorly known as a result of the paucity of preserved evidence from the Late Cenozoic in such areas. Endorheic basins that survive at the present day are mainly in regions of relative aridity and are often controlled by active tectonic structures, such as the pull-apart basins of the Dead Sea Fault Zone and similar examples. This review discusses the evidence from different climatic regions, tectonic settings and areas of different crustal type, with a view to elucidating meaningful patterns that might throw light on this phenomenon.Broman, E., Sun, X., Stranne, C., Salgado, M.G., Bonaglia, S., Geibel, M., Jakobsson, M., Norkko, A., Humborg, C., Nascimento, F.J.A., 2020. Low abundance of methanotrophs in sediments of shallow boreal coastal zones with high water methane concentrations. Frontiers in Microbiology 11, 1536. doi: 10.3389/fmicb.2020.01536. zones are transitional areas between land and sea where large amounts of organic and inorganic carbon compounds are recycled by microbes. Especially shallow zones near land have been shown to be the main source for oceanic methane (CH4) emissions. Water depth has been predicted as the best explanatory variable, which is related to CH4 ebullition, but exactly how sediment methanotrophs mediates these emissions along water depth is unknown. Here, we investigated the relative abundance and RNA transcripts attributed to methane oxidation proteins of aerobic methanotrophs in the sediment of shallow coastal zones with high CH4 concentrations within a depth gradient from 10–45 m. Field sampling consisted of collecting sediment (top 0–2 cm layer) from eight stations along this depth gradient in the coastal Baltic Sea. The relative abundance and RNA transcripts attributed to the CH4 oxidizing protein (pMMO; particulate methane monooxygenase) of the dominant methanotroph Methylococcales was significantly higher in deeper costal offshore areas (36–45 m water depth) compared to adjacent shallow zones (10–28 m). This was in accordance with the shallow zones having higher CH4 concentrations in the surface water, as well as more CH4 seeps from the sediment. Furthermore, our findings indicate that the low prevalence of Methylococcales and RNA transcripts attributed to pMMO was restrained to the euphotic zone (indicated by Photosynthetically active radiation (PAR) data, photosynthesis proteins, and 18S rRNA data of benthic diatoms). This was also indicated by a positive relationship between water depth and the relative abundance of Methylococcales and pMMO. How these processes are affected by light availability requires further studies. CH4 ebullition potentially bypasses aerobic methanotrophs in shallow coastal areas, reducing CH4 availability and limiting their growth. Such mechanism could help explain their reduced relative abundance and related RNA transcripts for pMMO. These findings can partly explain the difference in CH4 concentrations between shallow and deep coastal areas, and the relationship between CH4 concentrations and water depth.Burdel’naya, N.S., Bushnev, D.A., Golubev, E.A., Derevesnikova, A.A., Radaev, V.A., 2020. Thermolysis of asphaltenes of Timan–Pechora heavy oils. Petroleum Chemistry 60, 699-708. hydrocarbon composition of the thermolysis products of asphaltenes from biodegraded oils of the Labagan and Usa oilfields and non-biodegraded oil of the Salyukinskoe oilfield of the Timan–Pechora sedimentary basin has been studied. The IR spectra of the asphaltenes are identical, indicating their similar structural group composition. The thermolysis of the asphaltenes has been carried out in an argon flow successively at 300 and 350°C. It has been shown that desorption of saturated and aromatic components from the pores of the asphaltenes predominantly occurs at 300°C. For the initial biodegraded oils and the oil that did not undergo biochemical oxidation, a number of geochemical parameters calculated in terms of acyclic hydrocarbons (HCs) and polycyclic biomarkers turns out to be similar to those obtained for the thermolysis products of the asphaltenes heated at 350°C. The values of the methylphenanthrene index are similar for the thermolysis products of asphaltenes and the parent oils. This similarity, in turn, allows the genetic identification of oils and evaluation of their catagenetic maturity by asphaltene thermolysis products in the case when biomarkers of the aliphatic fraction are lost during biodegradation. An analysis of the supermolecular structure of the asphaltenes of the oils under study has shown a general trend of its change by heating at 350°C, which consists in a sharp decrease in the particle size and loosening of the particle packing due to the appearance of pronounced porosity.Canfield, D.E., Bjerrum, C.J., Zhang, S., Wang, H., Wang, X., 2020. The modern phosphorus cycle informs interpretations of Mesoproterozoic Era phosphorus dynamics. Earth-Science Reviews 208, 103267. cycles of phosphorus, carbon and oxygen are intimately linked. Indeed, in many models, phosphorus is considered the driver of the carbon and oxygen cycles, and low concentrations of atmospheric oxygen during the Mesoproterozoic Era have been linked to extreme phosphorus limitation in the Mesoproterozoic oceans. To evaluate the Mesoproterozoic Era phosphorus cycle, we analyze the concentrations of phosphorus, organic carbon, and selected trace metals in several geological formations of Mesoproterozoic age. We combine these analyses with literature data to explore the relationship between phosphorus and organic carbon removal into Mesoproterozoic Era sediments through a variety of water depths and water-column chemistries. We find that the ratio of organic carbon to reactive phosphorus (Corg/Preact) is largely invariant between different paleo-settings with average Corg/Preact that is either equal to or less than the Redfield ratio of 106/1 through all environments we explored. We put these results in the context of the modern phosphorus cycle which is reviewed here. Compared to modern phosphorus dynamics, we see no evidence for an anoxic-euxinic feedback between phosphorus burial, carbon burial and oxygen production during Mesoproterozoic times. However, we do identify an additional potential phosphorus feedback related to the relationship between anoxia and deep-sea phosphorus dynamics that could have importance in oxygen regulation through time. We find that the average value of Corg/Preact during the Mesoproterozoic Era was greater than the average for modern sediments. This result suggests that equal or more organic carbon was buried per unit of phosphorus during Mesoproterozoic times compared to today, a conclusion broadly consistent with the carbon isotope record. These results offer the possibility of a strong oxygen source to the atmosphere during the Mesoproterozoic Era, raising the conundrum as to why atmospheric oxygen levels were lower then when compared to now. We suggest that a variety of factors may explain these differences in oxygen concentration including elevated rates of mantle degassing, reduced rates of phosphorus weathering and the lack of a terrestrial biosphere.Cao, H., Zou, Y.-R., Peng, P.a., 2020. Tracing the origin of petroleum using asphaltene carbon isotope ratios: Case study from the Songliao Basin, NE China. Petroleum Science and Technology 38, 447-453. I and II kerogens, isolated from outcrop shales in the Songliao Basin, were performed a programed sealed-heating kinetic process. Both carbon isotope values of pyrolysis-residual kerogens and those of asphaltene extractions present gradual enrichments dependence on increasing Easy %Ro and biomarker maturity ratios. The carbon isotope (δ13C) values are used for the first time to analyze a close relationship between these kerogens and asphaltenes at the same level of thermal maturation, and identification oil–source rock correlation studies in theory. Such validity of the model was further tested by δ13C of asphaltenes and biomarker ratios in crude oils.Cao, M., Rivas-Ruiz, P., Trapote, M.d.C., Vegas-Vilarrúbia, T., Rull, V., Rosell-Melé, A., 2020. Seasonal effects of water temperature and dissolved oxygen on the isoGDGT proxy (TEX86) in a Mediterranean oligotrophic lake. Chemical Geology 551, 119759. appraise the application of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) as paleoclimate proxies in small lakes we investigated the effect of seasonal variability in temperature and dissolved oxygen concentration (DO) on the GDGT contents and its proxy in the water column of an oligotrophic karst lake in the Catalan pre-Pyrenees (Lake Montcortés). From October 2013 to November 2014, we collected suspended particulate matter (SPM) monthly at three depths and retrieved the sediment from a trap located at 20 m below the lake surface. The GDGT contents in the SPM and sediment trap presented a marked seasonal variation, showing the highest values in summer and autumn. In addition, the isoGDGT proxy TEX86 in SPM and sediment trap showed a marked seasonal variability which matched the temperatures of the upper water column and fit the published global trend between TEX86 and mean annual lake surface temperature (LST). However, in the hypolimnion where oxygen was depleted for most of the study period, we found that TEX86 co-varied with DO. This further confirms previous claims with seasonal field data that the sedimentary TEX86 LST signal may be confounded by DO conditions. Consequently, the application of TEX86 to estimate LST should be carefully appraised in environments with depleted DO conditions.Cao, Y.-H., Chen, W., Wang, T.-X., Yuan, Y.-N., 2020. Thermally enhanced shale gas recovery: microstructure characteristics of combusted shale. Petroleum Science 17, 1056-1066., thermal recovery technologies such as combustion have been studied for shale gas recovery. Thus, understanding of the microstructure of combusted shale is essential for evaluating the effects of thermal treatment on shale gas transport capacity. In this study, the effect of combustion on shale microstructure changes was investigated. Firstly, different-sized shale samples were combusted at 450?°C for 30?min. Afterward, shale microstructure properties including surface topographies, porosity and permeability of the raw and combusted shale samples were measured and compared. It was found that the pore volume and specific surface area increased after combustion, especially for small pulverized samples. According to surface topography obtained from atomic force microscope, more rough surfaces were obtained for the combusted shale due to larger pores and generation of thermal fractures caused by the removal of organic matter. Based on the mercury intrusion porosimetry measurements, the porosity of the shale samples increased from 2.79% to 5.32% after combustion. In addition, the permeability was greatly improved from 0.0019 to 0.6759?mD, with the effective tortuosity decreased from 1075.40 to 49.27. As a result, combustion treatment can significantly improve the gas transport capacity.Caquineau, T., Paquette, J.-L., Gannoun, A., Philippot, P., 2020. Lu-Hf systematics of 4.0 – 2.3?Ga old zircons from the Turee Creek Group (Pilbara Craton, W. Australia): Implications on the rise of atmospheric oxygen and global glaciation during the Paleoproterozoic. Precambrian Research 348, 105859. investigated the Hf isotopic systematics of detrital zircons in a succession of siliciclastic sediments and glacial diamictites from the early Paleoproterozoic sequence of the Boolgeeda Iron Formation (Hamersley Group) and overlying Turee Creek Group of the Pilbara Craton, Western Australia. About 400 detrital zircons yielding >95% concordant U-Pb ages were analyzed for Hf isotopes to constrain their magmatic sources. 70% of the analyzed zircons display super-chondritic initial Hf isotopic compositions, demonstrating crystallization in mantle-derived magmas. Most of the data are comprised between model age lines at ~2.5 and 3.2?Ga, which suggests a sub-continuous crust generation by extraction from the depleted mantle during this time period. A single grain yields a 4.0?Ga age, which represents the first Hadean age for a zircon from the Pilbara Craton. Our results are significantly different from zircon Hf isotope data of the Glenburgh Terrane, in the southern border of the Turee Creek Group, or older successions of the Pilbara, Kaapvaal and Superior cratons, but show overlap with some of the Yilgarn Craton. This together with the occurrence of a Hadean zircon crystal preserved in the Boolgeeda glacial diamictite with similar Hf isotopic signature than the Jack Hills zircons makes the Yilgarn Craton a possible source material for the Boolgeeda glacial horizon. Alternatively, the majority of the zircons analyzed show ages which are consistent with those of the underlying 2.45–2.78?Ga Hamersley and Fortescue groups, formed by sedimentary successions interleaved with thick subaerial volcanic sequences associated with the emplacement of Large Igneous Provinces. Such subaerial volcanic rocks could account for the relatively juvenile character of the zircon analyzed. A local provenance of the siliciclastic material delivered to the Turee Creek Basin would support the role of large subaerial magmatic provinces as triggers of the rise of atmospheric oxygen and the onset of glaciations at the beginning of the Proterozoic.Carraro, L., M?chler, E., Wüthrich, R., Altermatt, F., 2020. Environmental DNA allows upscaling spatial patterns of biodiversity in freshwater ecosystems. Nature Communications 11, 3585. alarming declines of freshwater biodiversity call for efficient biomonitoring at fine spatiotemporal scales, such that conservation measures be grounded upon accurate biodiversity data. Here, we show that combining environmental DNA (eDNA) extracted from stream water samples with models based on hydrological first principles allows upscaling biodiversity estimates for aquatic insects at very high spatial resolution. Our model decouples the diverse upstream contributions to the eDNA data, enabling the reconstruction of taxa distribution patterns. Across a 740-km2 basin, we obtain a space-filling biodiversity prediction at a grain size resolution of 1-km long stream sections. The model’s accuracy in matching direct observations of aquatic insects’ local occurrence ranges between 57–100%. Our results demonstrate how eDNA can be used for high-resolution biodiversity assessments in rivers with minimal prior knowledge of the system. Our approach allows identification of biodiversity hotspots that could be otherwise overlooked, enabling implementation of focused conservation strategies.Carri?o, ?.R., Marques, J., Trujillo-Rodriguez, M.J., Anderson, J.L., Rocha, S.M., 2020. Sorbent coatings for solid-phase microextraction targeted towards the analysis of death-related polar analytes coupled to comprehensive two-dimensional gas chromatography: Comparison of zwitterionic polymeric ionic liquids versus commercial coatings. Microchemical Journal 158, 105243. of bodies generates several types of polar volatile organic compounds (VOCs), whose types, patterns and ratios change during the various stages of decomposition and, therefore, their determination has huge potential to provide useful information to disclose events related to the time of death, or body surrounding environment. As sample preparation is a mandatory key-point in a method development, this research aims to develop a simple, accurate and rapid approach to study death-related polar VOCs based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC × GC-ToFMS) analysis. The performance of zwitterionic PIL-based fibers (containing a [VIm+C9COO?] monomer and a [(VIm)2C122+]-2Br? crosslinker), tailored for polar compounds, was evaluated for a set of 19 analytes associated with the unique odour created by decomposing bodies, and it was compared to the commercially-available fibers: divinylbenzene/carboxen/poly(dimethylsiloxane) – DVB/CAR/PDMS, poly(dimethylsiloxane)/divinylbenzene – PDMS/DVB and polyacrylate (PA). Fibers with absorptive-type mechanism, such as PA and PIL, showed the best results in the balance of the parameters studied, being able to detect analytes at ng level and providing a profile representative of the headspace composition, thus they may represent a useful tool to respond to current challenges in forensic taphonomy. The reproducibility (with relative standard deviation lower than 18%, depending on the analyte) and relative recoveries (higher than 99.1%) were similar and acceptable for both fibers. The zwitterionic PIL, with ca. 4 times smaller film thickness than PA, still has potential to have the best performance, supported by the efforts to obtain thicker sorbent coatings.Carrión, O., McGenity, T.J., Murrell, J.C., 2020. Molecular ecology of isoprene-degrading bacteria. Microorganisms 8, 967. is a highly abundant biogenic volatile organic compound (BVOC) that is emitted to the atmosphere in amounts approximating to those of methane. The effects that isoprene has on Earth’s climate are both significant and complex, however, unlike methane, very little is known about the biological degradation of this environmentally important trace gas. Here, we review the mechanisms by which bacteria catabolise isoprene, what is known about the diversity of isoprene degraders in the environment, and the molecular tools currently available to study their ecology. Specifically, we focus on the use of probes based on the gene encoding the α-subunit of isoprene monooxygenase, isoA, and DNA stable-isotope probing (DNA-SIP) alone or in combination with other cultivation-independent techniques to determine the abundance, diversity, and activity of isoprene degraders in the environment. These parameters are essential in order to evaluate how microbes might mitigate the effects of this important but neglected climate-active gas. We also suggest key aspects of isoprene metabolism that require further investigation in order to better understand the global isoprene biogeochemical cycle.?asait?, V., Stanislauskien?, R., Vaitekūnas, J., Taurait?, D., Rutkien?, R., Gasparavi?iūt?, R., Me?kys, R., 2020. Microbial degradation of pyridine: A complete pathway in Arthrobacter sp. strain 68b deciphered. Applied and Environmental Microbiology 86, e00902-20.: Pyridine and its derivatives constitute the majority of heterocyclic aromatic compounds that occur largely as a result of human activities and contribute to environmental pollution. It is known that they can be degraded by various bacteria in the environment; however, the degradation of unsubstituted pyridine has not yet been completely resolved. In this study, we present data on the pyridine catabolic pathway in Arthrobacter sp. strain 68b at the level of genes, enzymes, and metabolites. The pyr gene cluster, responsible for the degradation of pyridine, was identified in a catabolic plasmid, p2MP. The pathway of pyridine metabolism consisted of four enzymatic steps and ended by the formation of succinic acid. The first step in the degradation of pyridine proceeds through a direct ring cleavage catalyzed by a two-component flavin-dependent monooxygenase system, encoded by pyrA (pyridine monooxygenase) and pyrE genes. The genes pyrB, pyrC, and pyrD were found to encode (Z)-N-(4-oxobut-1-enyl)formamide dehydrogenase, amidohydrolase, and succinate semialdehyde dehydrogenase, respectively. These enzymes participate in the subsequent steps of pyridine degradation. The metabolites of these enzymatic reactions were identified, and this allowed us to reconstruct the entire pyridine catabolism pathway in Arthrobacter sp. 68b.Importance: The biodegradation pathway of pyridine, a notorious toxicant, is relatively unexplored, as no genetic data related to this process have ever been presented. In this paper, we describe the plasmid-borne pyr gene cluster, which includes the complete set of genes responsible for the degradation of pyridine. A key enzyme, the monooxygenase PyrA, which is responsible for the first step of the catabolic pathway, performs an oxidative cleavage of the pyridine ring without typical activation steps such as reduction or hydroxylation of the heterocycle. This work provides new insights into the metabolism of N-heterocyclic compounds in nature.Casalbore, D., Ingrassia, M., Pierdomenico, M., Beaubien, S.E., Martorelli, E., Bigi, S., Ivaldi, R., DeMarte, M., Chiocci, F.L., 2020. Morpho-acoustic characterization of a shallow-water mud volcano offshore Scoglio d'Affrica (Northern Tyrrhenian Sea) responsible for a violent gas outburst in 2017. Marine Geology 428, 106277. violent gas outburst occurred offshore the Scoglio d'Affrica islet (Tuscan Archipelago, Northern Tyrrhenian Sea) on March 16th 2017, with local fishermen observing columns of dirty water rising up to 10 m above the sea surface. The integration of video footage and dissolved CH4 measurements collected 5 days after the event with high-resolution multibeam data collected 4 months later, allowed us to characterize the source area of the outburst, corresponding to a shallow-water mud volcano. The mud volcano covers an area of ca. 170,000 m2, has a vertical relief of ca. 30 m with respect to the surrounding seafloor and an estimated volume of ca. 1 × 106 m3, based on bathymetric reconstruction. The elongated NNW-SSE shape of the mud volcano is compatible with local structural trends, indicating a tectonic control for its development. The mud volcano is made up of two mounds whose tops are located at a depth of ca. 10 m. The southern mound was responsible for the 2017 outburst, as testified by a 15–20 m wide circular crater on its summit where a large amount of mud breccia and diffuse seepage from small pockmarks were observed in video footage . The flanks of the mud volcano are steep and characterized in the upper part by a hummocky morphology and multiple sediment flows on the western flank.The characterization of the mud volcano and the deposits associated with the 2017 gas outburst provides insight into seafloor-shaping processes linked to fluid seepage in shallow-water sectors. This is a particularly relevant issue considering both the paucity of studies on shallow-water mud volcanoes as well as the hazard associated with violent gas outbursts in such settings, as witnessed by the March 16th 2017 event.Castro, D., Souto, M., Fraga, M.I., García-Rodeja, E., Pérez-Díaz, S., López Sáez, J.A., Pontevedra-Pombal, X., 2020. High-resolution patterns of palaeoenvironmental changes during the Little Ice Age and the Medieval Climate Anomaly in the northwestern Iberian Peninsula. Geoscience Frontiers 11, 1461-1475. high resolution core (9.7 ?yr ?cm?1) from the Chao de Veiga Mol raised bog (NW Iberian Peninsula) was analyzed to identify plant macrofossils, estimate peat humification and calculate hydroclimatic indices based on current bog species, with the overall aim of determining the climate conditions associated with evolution of the bog during the Medieval Climate Anomaly and the Little Ice Age. These proxies, together with historical and climate data, proved to be good indicators of the changes in bog surface wetness.Analysis of the core led to identification of 9 different periods: two corresponding to the so-called Medieval Climate Anomaly (930 to 1345 AD, 1075–665 calibrated years before present [cal. yr BP]); four corresponding to the Little Ice Age (1345 to 1905 AD; 665–105 ?cal ?yr BP); and three corresponding to the last century (1905 to 2000 AD). The findings revealed a generally dry climate that lasted until the 14th century, followed by a transition to a long period with a more humid, but characteristically very variable climate, which ended at the beginning of the 20th century and was followed by a rapid transition to more humid conditions and finally, a change to drier conditions.The Medieval Climate Anomaly was indicated by the abundance of dry-adapted mosses (Leucobryum glaucum, Hypnum cupressiforme) and characterized by warm dry conditions and high levels of peat humification, with alternating wet phases. The LIA period was dated by a large abundance of Sphagnum species (an indicator of wetness) and a gradual increase in the humification index. However, four different climate phases were differentiated in this period.High-resolution reconstruction of the evolution of the CVM bog and the multiproxy approach have together enabled a more detailed identification of climatic variations in this area, which are generally consistent with the global models, as well as better definition of the elusive climatic oscillations in the last millennium and confirmation of the importance of local modulation of global models.The study provides new information and a detailed chronology of climatic events that will help to refine local modulation of the climate evolution model in the still quite unexplored region of the NW Iberian Peninsula, a key area for understanding the paleoclimatic dynamics in SW Europe.Chandra, D., Vishal, V., 2020. A comparison of nano-scale pore attributes of Barakar Formation gas shales from Raniganj and Wardha Basin, India using low pressure sorption and FEG-SEM analysis. Journal of Natural Gas Science and Engineering 81, 103453. study investigates the micropore-mesopore spectrum in gas shales by augmenting two different pore size distribution calculation methods using two probe gases in low-pressure sorption analysis. The Barakar Formation shale samples collected from Wardha and Asansol belonging to two key potential basins in India, namely Wardha and Raniganj, were studied to identify possible variations in pore attributes in shales, and a comparison was drawn. A combination of CO2 and N2 low-pressure gas adsorption studies was implemented to resolve micro- and meso-pores, using the respective probe adsorbate. The visual representation of the pore structure and its disposition was facilitated by high-resolution microscopic imaging, and aided by image analysis. The results show a positive correlation between clay mineral composition and the mesopore attributes as well as organic matter composition and micropore attributes. This confirms that both inorganic and organic content of shales contains large pore volumes, albeit in different pore dimension ranges with some overlap. High N2 adsorption potential of Asansol shale, as well as high CO2 adsorption potential of Wardha valley shale, is conformable with their respective pore size distributions. Fractal characteristics of mesopores suggest that the larger mesopores have a rougher surface, whereas the smaller mesopores have a smoother surface (with average fractal dimensions of 2.6 and 2.2, respectively). Although all examined shales belong to the same geological formation, they exhibit distinctly variable pore attributes and gas storage potential.Chandra, D., Vishal, V., Debbarma, A., Banerjee, S., Pradhan, S.P., Mishra, M.K., 2020. Role of composition and depth on pore attributes of Barakar Formation gas shales of Ib Valley, India, using a combination of low-pressure sorption and image analysis. Energy & Fuels 34, 8085-8098. characterization of shale has gained attention over the years because it provides a good estimate of the total storage capacity of a gas shale reservoir. Ib Valley is a potential shale gas reservoir in India, and this study is a systematic pore analysis of these Barakar Formation shales. A combination of low-pressure gas adsorption and high-resolution scanning electron microscopy coupled with image analysis was used to characterize the pore structure and pore size distribution. The changes in pore attributes with increasing depth, varying mineral composition, and organic matter content were established. We observed a steady decrease in the micropore volume and carbon content with depth. We could successfully segregate the organic matter pores and inter- and intraparticle pores using the scanned images. Both CO2 and N2 adsorption experiments indicate high adsorption and, thereby, good gas storage capacity in the shales from shallower depth. The decrease in the micropore volume with depth may be related to higher compaction and reduced organic carbon content. From a fundamental point of view, the CO2 grand canonical Monte Carlo model shows better fitting in calculation of the pore size distribution compared to the CO2 density functional theory model.Chang, K.-Y., Riley, W.J., Crill, P.M., Grant, R.F., Saleska, S.R., 2020. Hysteretic temperature sensitivity of wetland CH4 fluxes explained by substrate availability and microbial activity. Biogeosciences Discussions 2020, 1-38. (CH4) emissions from wetlands are likely increasing and important in global climate change assessments. However, contemporary terrestrial biogeochemical model predictions of CH4 emissions are very uncertain, at least in part due to prescribed temperature sensitivity of CH4 production and emission. While statistically consistent apparent CH4 emission temperature dependencies have been inferred from meta-analyses across microbial to ecosystem scales, year-round ecosystem-scale observations have contradicted that finding. Using flux observations and mechanistic modeling in two heavily studied high-latitude research sites (Stordalen, Sweden, and Utqia?vik, Alaska, USA), we show here that substrate-mediated hysteretic microbial and abiotic interactions lead to intra-seasonally varying temperature sensitivity of CH4 production and emission. We find that seasonally varying substrate availability drives lower and higher modeled methanogen biomass and activity, and thereby CH4 production, during the earlier and later periods of the thawed season, respectively. Our findings demonstrate the uncertainty of inferring CH4 emission or production from temperature alone, and highlight the need to represent microbial and abiotic interactions in wetland biogeochemical models.Chang, Q., Wang, M., Zhang, G., Zang, X., Li, H., Zhang, S., Wang, C., Wang, Z., 2020. Carbon nanospheres as solid-phase microextraction coating for the extraction of polycyclic aromatic hydrocarbons from water and soil samples. Journal of Separation Science 43, 2594-2601. solid‐phase microextraction with carbon nanospheres coated fiber coupled with gas chromatographic detection was established for the determination of eight polycyclic aromatic hydrocarbons (naphthalene, biphenyl, acenaphthene, fluorine, phenanthrene, anthracene, fluoranthene, and pyrene) in water and soil samples. The experimental parameters (extraction temperature, extraction time, stirring rate, headspace volume, salt content, and desorption temperature) which affect the extraction efficiency were studied. Under the optimized conditions, good linearity between the peak areas and the concentrations of the analytes was achieved in the concentration range of 0.5‐300 ng/mL for water samples, and in the concentration range of 6.0‐2700 ng/g for soil samples. The detection limits for the analytes were in the range of 0.12‐0.45 ng/mL for water samples, and in the range of 1.53‐2.70 ng/g for soil samples. The method recoveries of the polycyclic aromatic hydrocarbons for spiked water samples were 80.10‐120.1% with relative standard deviations less than 13.9%. The method recoveries of the analytes for spiked soil samples were 80.40‐119.6% with relative standard deviations less than 14.4%. The fiber was reused over 100 times without a significant loss of extraction efficiency.Chaudhary, V., Kumar, S., 2020. Marine oil slicks detection using spaceborne and airborne SAR data. Advances in Space Research 66, 854-872. transportations have grown exponentially in the past few years’ and the quantity of illegitimate oil discharges in the oceans has developed with the volume of traffic imposing a severe threat to marine lives and ecosystem. Oil spills dampen the capillary wave’s effect hence create a dark signature on satellite image which is often called a dark object/matter that can be easily detected by SAR sensors. This study reviews the potential of quad-pol and hybrid-pol datasets in detecting oil spills. The data used for this study is the UAVSAR quad-pol and RISAT-1 hybrid/compact-pol dataset. These datasets were acquired during an oil spill experiment named the Norwegian Radar oil Spill Experiment (NORSE2015) which was carried out in the North Sea in June 2015. Basic pre-processing and decomposition modeling techniques namely Freeman and Durden, Van-Zyl, Yamaguchi, and Multiple-Component Scattering Model (MCSM) were applied on UAVSAR dataset, while Raney and Compact-Pol decompositions were applied to RISAT-1 dataset to know different surface backscattering behavior shown by the sea and oil patches. It was observed that Van-Zyl decomposition for UAVSAR and Compact-Pol decomposition for the RISAT-1 dataset gave the most suitable outcome based on the separability analysis to distinguish between oil and water. Two classification techniques Wishart Supervised Classifier (WSC) and Support Vector Machine (SVM) classifications were implemented on decomposed scattering elements of Van-Zyl and Compact-Pol. Radial Basis Function (RBF) kernel parameter values in SVM were used to precisely classify the oil patches from seawater. All the applied decomposition experiments provide good separability between water and oil. Later on, WSC and SVM had been used to finally classify both the dataset outputs. WSC had given better results with an accuracy of 83% for UAVSAR and 86% for RISAT-1, with a larger window size by minimizing the misclassification of sea class into oil spill class. Later the paper concludes the scope of further research possibilities for making a robust system for detecting the oil spills, both precisely and effectually.Chen, C., Lu, S., Zhang, P., Li, J., Li, W., Wang, S., 2020. Key factors influencing the low-field NMR characterisation of gas- and oil-bearing shales: a case study of the shales from the southern Sichuan Basin and Dongying sag, China. International Journal of Oil, Gas and Coal Technology 24, 466-482. response characteristics of transverse relaxation time (T2) of key experimental parameters [waiting time (TW), number of scans (NS) and echo number (NECH)], sample size and probe fluid, are analysed systematically based on NMR experiments of oil- and gas-bearing shales from the Shahejie Formation in Dongying sag and the Wufeng and Longmaxi Formations in the southern Sichuan Basin. The results indicate that: 1) the optimised NMR parameters for TW, NS and NECH are 1,500 ms, 64 and 6,000, respectively, which will ensure higher accuracy and signal-to-noise ratio (SNR); 2) the total signal amplitude of the T2 spectrum increases with decreasing grain size. The T2 spectra of shale which grain size bigger than 10 mesh can characterize the shale PSD; 3) water porosity clearly decreases with increasing brittle minerals but decreasing clay content than n-dodecane-saturated porosity, which indicates the hydration of clay and brittle minerals together controls the reconstruction of PSD.Chen, H., Liu, X., Blosser, G.D., Rücker, A.M., Conner, W.H., Chow, A.T., 2020. Molecular dynamics of foliar litter and dissolved organic matter during the decomposition process. Biogeochemistry 150, 17-30. foliar litter organic matter (LOM) in forested watersheds is an essential terrestrial source of dissolved organic matter (DOM) to aquatic ecosystems. To evaluate the relationship of chemical composition between LOM and DOM, we collected freshly fallen leaves of white oak (Quercus alba) and conducted an 80-week field decomposition experiment along a small elevation gradient in a floodplain within the Congaree National Park, South Carolina. Foliar litters were collected for water extraction and instrumental analyses using pyrolysis GC/MS, UV/VIS and fluorescence spectrophotometry. Factor analyses of pyrolysates showed that fresh LOM was mainly composed of lignin compounds (LgC), phenolic compounds (PhC), and carbohydrate (Carb), and the change in composition was relatively small throughout the decomposition process. In contrast, there were two distinct chemical compositions of DOM in early (between 0–8?weeks) and late phases (between 16–80?weeks). The early phase had a higher percentage of PhC, but the late phase contained higher percentages of Carb, unsaturated hydrocarbon (UnSaH), aromatic hydrocarbon (ArH), and nitrogen-containing compounds (Ntg). The fluorescence emission-excitation matrix showed there was an increasing trend in humic and fulvic-like fractions in DOM over time, matching well with increases of UnSaH and ArH fractions from the results of pyrolysis GC/MS. Our study illustrated that the changes of chemical components in LOM and water extractable DOM were not parallel during the decomposition process and the degradation of lignin and phenolic compounds was one of the controlling factors on the production of DOM.Chen, H., Parry, L.A., Vinther, J., Zhai, D., Hou, X., Ma, X., 2020. A Cambrian crown annelid reconciles phylogenomics and the fossil record. Nature 583, 249-252. phylum of annelids is one of the most disparate animal phyla and encompasses ambush predators, suspension feeders and terrestrial earthworms. The early evolution of annelids remains obscure or controversial, partly owing to discordance between molecular phylogenies and fossils. Annelid fossils from the Cambrian period have morphologies that indicate epibenthic lifestyles, whereas phylogenomics recovers sessile, infaunal and tubicolous taxa as an early diverging grade. Magelonidae and Oweniidae (Palaeoannelida) are the sister group of all other annelids but contrast with Cambrian taxa in both lifestyle and gross morphology. Here we describe a new fossil polychaete (bristle worm) from the early Cambrian Canglangpu formation7 that we name Dannychaeta tucolus, which is preserved within delicate, dwelling tubes that were originally organic. The head has a well-defined spade-shaped prostomium with elongated ventrolateral palps. The body has a wide, stout thorax and elongated abdomen with biramous parapodia with parapodial lamellae. This character combination is shared with extant Magelonidae, and phylogenetic analyses recover Dannychaeta within Palaeoannelida. To our knowledge, Dannychaeta is the oldest polychaete that unambiguously belongs to crown annelids, providing a constraint on the tempo of annelid evolution and revealing unrecognized ecological and morphological diversity in ancient annelids.Chen, L., Li, H., Li, S., Xu, L., Lin, S., Zhou, H., 2020. Development of in-situ Micro-Raman spectroscopy system for autoclave experimental apparatus. Acta Geochimica 39, 445-450. developed a set of in-situ Micro-Raman spectroscopy system for autoclave experimental apparatus because of the scientific significance of in-situ Micro-Raman spectroscopy system under the high-pressure hydrothermal condition. We used this system to measure the Raman spectrum of water-fluid and quartz crystal at the temperature ranging from 125 to 420?°C. The signal-to-noise ratio of the Raman signal is good.Chen, T.-T., Paull, C.K., Liu, C.-S., Klaucke, I., Hsu, H.-H., Su, C.-C., Gwiazda, R., Caress, D.W., 2020. Discovery of numerous pingos and comet-shaped depressions offshore southwestern Taiwan. Geo-Marine Letters 40, 407-421. bathymetry collected with an autonomous underwater vehicle (AUV) along the flanks of three ridges of the accretionary prism offshore southwestern (SW) Taiwan revealed more than 650 elongated depressions in water depths ranging from 1155 to 1420 m. The depressions are between 12 and 129 m long, 5 to 70 m wide, and up 9 m deep at their center and shallowing downslope to about 1-m depth. Due to their shape in downslope cross section, they are termed comet-shaped depressions (CSD). The CSD occur in patches of more than 100 with densities of 53 to 98 CSD/km2. In addition, seven topographic mounds were mapped and interpreted as pingos, which remotely operate vehicle (ROV) observations and sampling show to be covered with authigenic carbonate. These features overlie areas where multichannel seismic reflection (MCS) profiles show bottom simulating reflectors (BSR) and dipping strata extending from below the BSR to near the seafloor. We consider comet-shaped depression, a new type of pockmark, forms on a sloping seafloor where fluids expulsion occurred. We also suggest that the two types of distinctive geomorphic features are attributed to fluid venting which occurs at different rates, with the mounds developing slowly over time, but the CSD forming in discrete events perhaps associated with large earthquakes.Chen, W., He, C., Gu, Z., Wang, F., Li, Q., 2020. Molecular-level insights into the transformation mechanism for refractory organics in landfill leachate when using a combined semi-aerobic aged refuse biofilter and chemical oxidation process. Science of The Total Environment 741, 140502. leachate contains high concentrations of complex organic matter (OM) that can severely impact the ecological environment. If landfill leachate is to be treated using a combined “biological + advanced treatment” process, the molecular information of OM must be investigated to optimize the operation parameters of the combined process and maximize the removal of organic pollutants. This study applied an ultra-high resolution mass spectroscopy to investigate the degradation and transformation characteristics of refractory OM in mature landfill leachate at the molecular level (m/z?=?150–800) during biological treatment (i.e., semi-aerobic aged refuse biofilter, SAARB) and subsequent chemical oxidation (i.e., the Fenton process and ozonation). After SAARB treatment, the polycyclic aromatics (aromatic index, AI?>?0.66) and polyphenol (0.66?≥?AI?>?0.50) contents increased, and the highly unsaturated phenolic compounds (AI?≤?0.50 and H/C?<?1.5), which have a high bioavailability, were mostly removed. Compared with raw leachate, SAARB effluent (i.e., SAARB leachate) contained fewer organics with short carbon chains, more organics with long carbon chains, an elevated condensation degree for organics and, thus, a considerably reduced biodegradability. Although both the Fenton and ozonation processes could remove many of the polycyclic aromatics and polyphenols, ozone produced considerable amounts of aliphatic compounds with high bioavailability. Compared to ozonation, the Fenton process utilized the hydroxyl radical to non-selectively react with OM and produced better mineralization results.Chen, W., He, C., Zhuo, X., Wang, F., Li, Q., 2020. Comprehensive evaluation of dissolved organic matter molecular transformation in municipal solid waste incineration leachate. Chemical Engineering Journal 400, 126003. of the molecular compositions of dissolved organic matter (DOM) in incineration leachate (IL) were investigated. Results revealed that DOM in IL had a lower oxidation degree than that in mature MSW landfill leachate (LL). Moreover, aliphatic compounds (2.0 ≥ H/C ≥ 1.5) having the highest bioavailability were the most abundant type of DOM in IL, making IL significantly more biodegradable than LL. Under microbial actions, etc., DOM composed of phenolic compounds (aromaticity index (AI) ≤ 0.50 and H/C < 1.5), polyphenols (0.66 ≥ AI > 0.50) and polycyclic aromatics (AI > 0.66) in MBR-treated effluents were enriched and more diverse than in the untreated leachates. Nanofiltration (NF) dramatically lowered the relative abundances of phenolic compounds, polyphenols and polycyclic aromatics in effluent generated by treatment of IL in a MBR. Although the concentration of DOM in NF effluent was comparatively low, the DOM compositions in the resulting NF concentrate were nearly identical to those in MBR effluent, but were more complex than those in an international standard DOM due to a higher content of CHOS and CHONS heteroatomic compounds. Particularly, coagulation in conjunction with ozone/hydrogen peroxide oxidation process were dramatically reduced most polyphenols and polycyclic aromatics from the NF concentrate.Chen, X., Li, M., Sperling, E.A., Zhang, T., Zong, K., Liu, Y., Shen, Y., 2020h. Mesoproterozoic paleo-redox changes during 1500–1400?Ma in the Yanshan Basin, North China. Precambrian Research 347, 105835. Mesoproterozoic (1600–1000 million years ago, Ma) is thought to have experienced important changes in ocean chemistry and eukaryote evolution. Our understanding of global redox conditions remains in its infancy, and redox data derived from the Mesoproterozoic thus far indicate heterogeneity and complexity in the realm of ocean redox, which hampers our understanding of the potential significance of variations in ocean redox on eukaryote evolution. In this study, we report analyses of Fe species and redox-sensitive trace metals of U and Mo from the Jixian Group, including the Wumishan, Hongshuizhuang and Tieling formations, as well as the Xiamaling Formation, in the Yanshan Basin in North China. The Fe speciation data from the Wumishan, Hongshuizhuang, and Tieling formations first reported in this study help bridge the global data gap of Fe species data during 1500–1400?Ma. Our data suggest likely oxic bottom water conditions for the Wumishan Formation and ferruginous bottom water conditions for the Tieling Formation. The Fe species data can distinguish ferruginous conditions for the upper Hongshuizhuang from sulfidic depositional conditions for the lower-middle Hongshuizhuang Formation. Based on Fe species and trace metal data, redox conditions likely varied from anoxic conditions with transient euxinia in the lower-middle Xiamaling Formation to oxic conditions in the upper Xiamaling Formation. The new Fe speciation data from the Yanshan Basin, when combined with previously published data, show a surprisingly high proportion of middle Proterozoic samples with very low highly reactive to total iron ratios. This suggests either a relatively large extent of oxic seafloor, or non-uniformitarian iron cycling. Resolving this discrepancy will be key to understanding the extent of suitable habitats for complex eukaryotes.Chiarenza, A.A., Farnsworth, A., Mannion, P.D., Lunt, D.J., Valdes, P.J., Morgan, J.V., Allison, P.A., 2020. Asteroid impact, not volcanism, caused the end-Cretaceous dinosaur extinction. Proceedings of the National Academy of Sciences 117, 17084-17093.: We present a quantitative test of end-Cretaceous extinction scenarios and how these would have affected dinosaur habitats. Combining climate and ecological modeling tools, we demonstrate a substantial detrimental effect on dinosaur habitats caused by an impact winter scenario triggered by the Chicxulub asteroid. We were not able to obtain such an extinction state with several modeling scenarios of Deccan volcanism. We further show that the concomitant prolonged eruption of the Deccan traps might have acted as an ameliorating agent, buffering the negative effects on climate and global ecosystems that the asteroid impact produced at the Cretaceous–Paleogene boundary.Abstract: The Cretaceous/Paleogene mass extinction, 66 Ma, included the demise of non-avian dinosaurs. Intense debate has focused on the relative roles of Deccan volcanism and the Chicxulub asteroid impact as kill mechanisms for this event. Here, we combine fossil-occurrence data with paleoclimate and habitat suitability models to evaluate dinosaur habitability in the wake of various asteroid impact and Deccan volcanism scenarios. Asteroid impact models generate a prolonged cold winter that suppresses potential global dinosaur habitats. Conversely, long-term forcing from Deccan volcanism (carbon dioxide [CO2]-induced warming) leads to increased habitat suitability. Short-term (aerosol cooling) volcanism still allows equatorial habitability. These results support the asteroid impact as the main driver of the non-avian dinosaur extinction. By contrast, induced warming from volcanism mitigated the most extreme effects of asteroid impact, potentially reducing the extinction severity.Chibwe, L., Roberts, S., Shang, D., Yang, F., Manzano, C.A., Wang, X., Kirk, J.L., Muir, D.C.G., 2020. A one-century sedimentary record of N- and S-polycyclic aromatic compounds in the Athabasca oil sands region in Canada. Chemosphere 260, 127641. atmospheric deposition of polycyclic aromatic compounds (PACs) is considered a major pathway to isolated lakes and bogs in the Athabasca oil sands region (AOSR), Canada. However, the suite of PACs measured has been limited. We report the detailed depositional history of nitrogen and sulphur heterocyclic PACs using a 210Pb dated sediment core (1914-2015) near major developments in the AOSR. We observed (1) an exponential growth in the deposition of heterocyclic PACs to recent times with an average doubling time of 12 years, (2) significant breakpoints in PAC fluxes in the mid to late 1980s, and (3) a synchronous increase of PACs with crude oil production (r2=0.82, p=0.001). NPACs were not detected prior to the 1960s in the sediment core studied, suggesting they may hold promise in serving as indicators for atmospheric PAC deposition of industrial origin. Furthermore, a change in heterocyclic PAC distribution profiles beginning in the 1970-1980s, after the onset of mining, resembling a petcoke signature, was also observed. Significant positive correlations (p<0.05) were observed between heterocyclic PACs, and several metal(loid)s, including priority pollutant elements, chromium and beryllium, and rare earth elements, cerium, lanthanum and yttrium (r2>0.75), suggesting the potential of a common source or similar transport and fate mechanisms. Significant negative or no correlations were observed between heterocyclic PACs and other metal(loid)s, including vanadium, total mercury and lead, possibly reflecting the impact of broader regulatory controls introduced in the mid-1970s on some metal(loids) but not on PACs, including the installation of electrostatic precipitators in major upgrader stacks.Chu, M., Sachs, J.P., Zhang, H., Ding, Y., Jin, G.e., Zhao, M., 2020. Spatiotemporal variations of organic matter sources in two mangrove-fringed estuaries in Hainan, China. Organic Geochemistry 147, 104066. systems represent important long-term sinks for carbon since they have much higher carbon burial rates than terrestrial forests or typical coastal ecosystems. However, quantifying the sources of organic matter (OM) in estuarine and coastal sediments, where mangroves occur but are not the only source of OM, is challenging due to the variety of OM sources and diverse transport processes in these dynamic environments. The sources of OM in subtidal surface sediments of two mangrove-fringed estuaries in Hainan Province, China, were investigated using the mangrove-specific biomarker taraxerol and other lipid biomarkers, as well as stable carbon isotopes. Mixing models based on the concentration of taraxerol, plant wax n-alkanes and δ13COM indicate that terrestrial non-mangrove plant OM accounted for 40–57% of the OM in the two estuaries, phytoplankton OM accounted for 24–45%, and OM from mangroves comprised 15–19% of the total. Terrestrial plants contributed 10–21% more of the OM to subtidal sediments of Bamen Bay, which is on the wetter, eastern side of Hainan Island, than to Danzhou Bay, but the phytoplankton OM fraction was 16–24% lower than that in Danzhou Bay subtidal sediments. In both estuaries, mangrove and phytoplankton OM fractions increased seaward while the terrestrial OM fraction decreased. On a seasonal basis, lipid biomarker concentrations indicated a small change of OM sources. The biomarker and carbon isotope approach used here can be applied to semi-quantitatively estimate spatial and temporal variations of the sources of organic carbon in tropical estuarine and coastal sediments, a major sink for carbon in the ocean.Cockell, C.S., Wilhelm, M.B., Perl, S., Wadsworth, J., Payler, S., McMahon, S., Paling, S., Edwards, T., 2020. 0.25 Ga salt deposits preserve signatures of habitable conditions and ancient lipids. Astrobiology 20, 864-877. features in a ～250 million-year-old Permian evaporitic deposit were investigated for their geological and organic content to test the hypothesis that they could preserve the signature of ancient habitable conditions and biological activity. Investigations on evaporitic rock were carried out as part of the MIne Analog Research (MINAR) project at Boulby Mine, the United Kingdom. The edges of the polygons have a higher clay content and contain higher abundances of minerals such as quartz and microcline, and clays such as illite and chlorite, compared with the interior of polygons, suggesting that the edges were preferred locations for the accumulation of weathering products during their formation. The mineral content and its strontium isotope ratio suggest that the material is from continental weathering at the borders of the Permian Zechstein Sea. The edges of the polygons contain material with mean δ13C and δ15N values of ?20.8 and 5.3, respectively. Lipids, including alkanes and hopanes, were extracted from the interior and edges of the polygons, which are inferred to represent organic material entrained in the evaporites when they were formed. The presence of long-chain alkanes (C20–C35) that lack a carbon preference, low abundances of C23–C29 hopanes, and lack of marine, evaporitic, or thermal maturity indicators show that lipid biomarkers were, at least in part, potentially derived from a continental source and have not undergone significant thermal maturation since deposition. Lipid extractions using weak acids revealed significantly more lipids than those without acid, potentially indicating that encapsulation was not the only type of preservation mechanism occurring in Boulby salts. These data demonstrate the potential for ancient evaporites and their polygons to preserve information on local geological conditions, ancient habitability, and evidence of life. The data show that analogous martian evaporitic deposits are good targets for future life detection missions and the investigation of ancient martian erio, M., Fernández, D.E., Rendtorff, N., Cipollone, M., Zalba, P.E., Pazos, P.J., 2020. Depositional and postdepositional processes of an oil-shale analog at the microstructure scale: The Lower Cretaceous Agrio Formation, Neuquén Basin, northern Patagonia. American Association of Petroleum Geologists Bulletin 104, 1679-1705. Lower Cretaceous Agrio Formation is a source rock considered to be a possible unconventional reservoir. However, no detailed microstructure characterization of this hydrocarbon play has been performed. An exceptional oil-prone level is determined through outcrop information, petrography, x-ray diffraction, geochemical analysis, and x-ray micro–computed tomography (μCT). Microscopic studies reveal a lenticular fabric and calcareous nannofossils suggesting high carbonate productivity in the water column and algal-derived organic matter. The high organic matter content points to anoxic–euxinic conditions consistent with pyrite framboids, authigenic fluorapatite, and an elevated concentration of redox-sensitive elements. However, burrows reveal the activity of infaunal organisms, thus rejecting the idea of persistent bottom-water anoxia. The bioturbated, calcareous plankton and carbonate-rich mudstone represents accumulation in a distal outer ramp setting with calcareous plankton blooms and the co-occurrence of benthic microbial mats. Bottom currents, probably as a consequence of storm-related processes, were involved in detrital transport and oxygenation pulses. A three-dimensional (3-D)–microstructure reconstruction reveals three main μCT density-dependent phases: (1) a low-density phase composed of organic matter and calcite, (2) an intermediate-density phase dominated by calcite and minor organic matter, and (3) a high-density phase composed of authigenic minerals (pyrite, marcasite, and fluorapatite) and silt-sized detrital quartz and plagioclase. This analysis showed that burial diagenesis did not create enough pore space to be evaluated through μCT and that besides mineralogy, particle-size distribution, particle arrangement (sorting), and the local compaction degree affect the 3-D reconstructed structure. The analyzed sample is located toward the carbonaceous end member of the shale spectrum and exemplifies new approaches for the characterization of carbonate oil shales in the unit and similar deposits. From the perspective of unconventional exploration, the evaluation of depositional and postdepositional controls on the resultant microstructure might contribute to a better understanding of potential target intervals within the Agrio Formation.Croswell, K., 2020. Inner Workings: Was Jupiter born beyond the current orbits of Neptune and Pluto? Proceedings of the National Academy of Sciences 117, 16716-16719. people named the planet Jupiter well. Both its brilliance and its slow, regal movement across the sky evoked a king among gods. Today we know much more about the influence of Jupiter, a planet boasting more than twice as much mass as the solar system’s other planets put together. Jupiter’s tremendous gravity stunted the growth of newborn Mars, sculpts the asteroid belt today, and may even help protect Earth from catastrophic comet impacts.But how did such a behemoth arise? Conventional theory says that Jupiter formed more or less where it is now, about five times farther from the Sun than Earth is. At that distance, the disk of gas and dust that swirled around the young Sun was dense enough to give birth to the planetary goliath.In 2019, however, two groups of researchers unaware of each other’s work—one in America (1), the other in Europe (2)—proposed a literally far-out alternative: Jupiter got its start in the solar system’s hinterlands, probably beyond the current orbits of Neptune and Pluto, and then moved inward.“It’s the most fun I’ve had with a paper for some time,” says Karin ?berg, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA, and one of the theory’s originators. “You can explain it to almost anyone in a couple of minutes.” The theory may be straightforward, but its consequences are profound: If it’s right, the solar system’s biggest planet was born some 10 times farther from the Sun than it now is, which means that some of the other giant worlds in our solar system and beyond likely arose at vast distances from their stars and then moved to their current locations.Nitrogen Provides a Solid ClueThe idea that planets can rove from far to near was itself once radical. But in 1995, this notion became standard thinking after the shocking discovery of a giant planet closer to its sun than Mercury is to ours. Planets form in so-called protoplanetary disks, pancake-shaped gatherings of gas and dust that revolve around newborn stars. Near the star, the protoplanetary disk is hot, so only rock and heavy elements such as iron can condense and make planets, whereas at larger distances water molecules, formed from plentiful hydrogen and oxygen, freeze and help create much bigger worlds. Thus, astronomers suspected that the strange close-in giant planet developed farther from its star and then, through interaction with the gas and dust in the disk, spiraled inward.Scientists later applied this idea of planetary migration to our solar system. In the Nice model, named for a city in France where the theory came together, the Sun’s giant planets were once so close together that their gravitational pulls tugged on one another and hurled Uranus and Neptune away from the Sun until they reached their present distances (3).The new theory doesn’t change the Nice model, but it does propose that, while still an infant, Jupiter made a much greater excursion across the solar system. Moreover, whereas the Nice model was silent on Jupiter’s origin, the new theory attacks that issue head on, focusing on a peculiarity in the planet’s atmosphere: It’s rich in nitrogen. “It’s actually something that started bothering me a few years ago,” ?berg says. “I can’t think of any way to explain it if Jupiter formed where it currently is sitting.”Molecular nitrogen is normally a gas, and most gases don’t glom onto planets in large amounts; only solids—or gases in their frozen state—do. But nitrogen freezes at temperatures far colder than those that prevailed in the protoplanetary disk at Jupiter’s present position, which means the planet shouldn’t have much of the element. Indeed, to find nitrogen as an ice, you have to travel to places such as Neptune’s moon Triton or far-off Pluto. In 1995, however, the Galileo probe dove into the Jovian atmosphere and measured a nitrogen-to-hydrogen ratio three to four times higher than the Sun’s. The larger ratio suggested that Jupiter had somehow acquired nitrogen in solid form.In both America and Europe, this was the starting point for the new theory. In each case its conception arose from a conversation. ?berg regularly visits with Harvard planetary scientist Robin Wordsworth. “I expressed my frustration with not being able to form Jupiter where it currently is,” ?berg recalls.Meanwhile, a similar discussion was unfolding in The Netherlands. “We started thinking: Well, OK, how can we get that extra nitrogen into Jupiter?” says Arthur Bosman, an astrochemist then at Leiden University in The Netherlands and now at the University of Michigan at Ann Arbor. He and his officemate, Alex Cridland, had both noticed the planet’s high nitrogen level.And it’s not just nitrogen. Argon, a noble gas, also freezes at frigid temperatures, and it too is abnormally abundant on Jupiter. Ditto for two other noble gases, krypton and xenon.Ahead of Its TimeIn a 1999 article, other researchers had noted these oddities, proposing possible explanations, including one which suggested that Jupiter migrated to its present position from beyond Neptune’s current orbit (4). But the idea was ahead of its time. For one thing, conventional theory then said planets built up from dust grains that slowly grew larger, eventually leading to asteroid-sized bodies which later merged; but this process was slow in the tenuous outskirts of the protoplanetary disk, so a planet as large as Jupiter wouldn’t have had enough time to arise there before the disk of gas and dust vanished.Since then, however, two new developments have made the bold idea more plausible. First, the Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope started operating in Chile and began imaging protoplanetary disks around newborn stars. The first such image, of a young star named HL Tauri, came out in late 2014.The picture was revolutionary. “It was difficult to believe that was a real image and not an artist’s impression,” ?berg says. It showed a disk of gas and dust with dark circular grooves. The grooves were presumably cut by unseen giant planets orbiting the star. Moreover, some of the grooves were much farther out than Neptune and Pluto are from the Sun, a sign that gas giants such as Jupiter can form even in remote regions.The second advance was theoretical. In recent years, researchers have formulated a new idea of planet formation called pebble accretion, which posits that a giant planet’s core builds up as small objects—pebbles—flow past a budding core and stick to it (5, 6). This process is “orders of magnitudes faster” than the conventional scenario, Bosman says. As a result, a giant planet’s core can spring forth even in the sparse outer reaches of a protoplanetary disk. Then, when the core grows massive enough, its gravitational pull attracts a topping of hydrogen and helium, which were the two main gases in the protoplanetary disk and are the two dominant elements composing Jupiter today. And if the planet had arisen in the coldest parts of the disk, Jupiter should have acquired plenty of nitrogen and argon ice, explaining why the atmosphere is rich in these elements.Even as the American and European teams were readying their papers for publication, neither knew about the other—until Bosman saw the American team’s paper on ArXiv just a day before he had planned to submit his own work. “It’s such a paradigm shift that I was really happy to see that someone else was thinking the same way,” he says. “On the other hand, someone else was first, and that was a bit of a bummer. But that’s how things go in science.” When ?berg learned of the other paper, she was “very happy,” she says. “It sort of gave me some confidence that maybe this idea wasn’t so strange after all.”Other researchers have noticed the radical new theory. “Ten years ago, people would have just rolled their eyes,” says Jonathan Fortney, a planetary scientist at the University of California at Santa Cruz. But thanks to pebble accretion theory, he says, that’s no longer the case. Although it “sounds a little crazy,” it’s not unreasonable that you could create the core of a giant planet beyond Pluto’s current orbit, Fortney says.David Stevenson, a planetary scientist at the California Institute of Technology in Pasadena, is more skeptical. “It’s not that difficult to come up with a variety of stories, given our lack of understanding,” he says. Furthermore, even if Jupiter’s core arose far from the Sun and thus acquired high levels of nitrogen and argon, he says it’s hard to get those elements up to the planet’s atmosphere, where the Galileo probe detected them; after all, the core constitutes only a small fraction of the planet. To solve this problem, ?berg and Wordsworth invoke a giant impact on Jupiter to lift the elements from the core to the atmosphere (7). “Well,” Stevenson says, “you can use a giant impact to do anything.”Et Tu, Saturn?Still, the theory for Jupiter’s distant birthplace does make testable predictions. The first concerns oxygen. In the protoplanetary disk, oxygen became part of silicates and water. These substances solidified closer to the Sun than nitrogen and argon did and also existed at greater distances, where the temperature was even colder. Thus, if Jupiter’s core formed beyond Pluto’s current orbit, the giant planet incorporated all of these elements as solids and should have similar overabundances of them all with respect to the Sun. Both articles therefore predict that Jupiter’s oxygen-to-hydrogen ratio is three to four times greater than the solar value.In February, Cheng Li, a planetary scientist at the University of California at Berkeley, and his team delivered a preliminary verdict. “Their prediction and our observations agree with each other,” Li says, although some uncertainty remains. His team reported that the Juno spacecraft now orbiting Jupiter had measured an oxygen-to-hydrogen ratio near the equator between one and five times solar, compatible with the prediction (8). But this range also means that Jupiter could still have the same oxygen-to-hydrogen level as the Sun, which would contradict the new theory. Li’s team aims to use Juno to refine the measurement in coming years.Both ?berg and Bosman point to another test the theory faces: Saturn, which should have formed beyond Jupiter. “That means we should see a similar pattern in the abundances in Saturn as we’re seeing in Jupiter,” Bosman says. Future probes to the ringed planet can therefore search for high levels of nitrogen and argon.Meanwhile, ?berg is pleased with the theory’s reception. “I met much less resistance than I expected,” she says. “The vast majority of reactions have been ‘Yeah, that kind of makes sense.’” And she can even explain the theory to her nonscientist neighbors.References1. K. I. ?berg, R. Wordsworth, Jupiter’s composition suggests its core assembled exterior to the N2 snowline. Astron. J. 158, 194 (2019).2. A. D. Bosman, A. J. Cridland, Y. Miguel, Jupiter formed as a pebble pile around the N2 ice line. Astron. Astrophys. 632, L11 (2019).3. S. Ornes, News Feature: Space fossils. Proc. Natl. Acad. Sci. U.S.A. 112, 3849–3851 (2015).4. T. Owen et al., A low-temperature origin for the planetesimals that formed Jupiter. Nature 402, 269–270 (1999).5. A. Johansen, M. Lambrechts, Forming planets via pebble accretion. Annu. Rev. Earth Planet. Sci. 45, 359–387 (2017).6. N. T. Redd, Inner Workings: Newborn stars don’t have enough dust to build planets. What are the missing ingredients? Proc. Natl. Acad. Sci. U.S.A. 116, 7605–7607 (2019).7. S.-F. Liu et al., The formation of Jupiter’s diluted core by a giant impact. Nature 572, 355–357 (2019).8. C. Li et al., The water abundance in Jupiter’s equatorial zone. Nat. Astron. 4, 609–616 (2020).Cui, X., Liu, X.-L., Shen, G., Ma, J., Husain, F., Rocher, D., Zumberge, J.E., Bryant, D.A., Summons, R.E., 2020. Niche expansion for phototrophic sulfur bacteria at the Proterozoic–Phanerozoic transition. Proceedings of the National Academy of Sciences 117, 17599-17606.: Carotenoid pigments afford valuable clues about the chemistry and biology of both modern and ancient aquatic environments. This study reveals that fossil aromatic carotenoids—long considered biomarkers for anoxygenic, phototrophic sulfur bacteria and their physiological requirement for hydrogen sulfide and illumination—can also be biosynthesized by oxygen-producing cyanobacteria. Cyanobacterial aromatic carotenoids, which are distinct in their chemical structures and occurrence patterns, are the most commonly encountered compounds in Proterozoic marine settings as well as in lakes from more recent eras. In contrast, carotenoids diagnostic for green sulfur bacteria of the family Chlorobiaceae became both prevalent and abundant in marine paleoenvironments beginning in the Phanerozoic Eon. This expansion occurs as marine sulfate inventories increased toward the end of the Proterozoic Eon.Abstract: Fossilized carotenoid hydrocarbons provide a window into the physiology and biochemistry of ancient microbial phototrophic communities for which only a sparse and incomplete fossil record exists. However, accurate interpretation of carotenoid-derived biomarkers requires detailed knowledge of the carotenoid inventories of contemporary phototrophs and their physiologies. Here we report two distinct patterns of fossilized C40 diaromatic carotenoids. Phanerozoic marine settings show distributions of diaromatic hydrocarbons dominated by isorenieratane, a biomarker derived from low-light-adapted phototrophic green sulfur bacteria. In contrast, isorenieratane is only a minor constituent within Neoproterozoic marine sediments and Phanerozoic lacustrine paleoenvironments, for which the major compounds detected are renierapurpurane and renieratane, together with some novel C39 and C38 carotenoid degradation products. This latter pattern can be traced to cyanobacteria as shown by analyses of cultured taxa and laboratory simulations of sedimentary diagenesis. The cyanobacterial carotenoid synechoxanthin, and its immediate biosynthetic precursors, contain thermally labile, aromatic carboxylic-acid functional groups, which upon hydrogenation and mild heating yield mixtures of products that closely resemble those found in the Proterozoic fossil record. The Neoproterozoic–Phanerozoic transition in fossil carotenoid patterns likely reflects a step change in the surface sulfur inventory that afforded opportunities for the expansion of phototropic sulfur bacteria in marine ecosystems. Furthermore, this expansion might have also coincided with a major change in physiology. One possibility is that the green sulfur bacteria developed the capacity to oxidize sulfide fully to sulfate, an innovation which would have significantly increased their capacity for photosynthetic carbon fixation.Curry, A., 2020. Tools suggest people reached Americas early, Science, pp. 355-356. first glance, Chiquihuite Cave in Mexico's Zacatecas state is an unlikely place to find signs of early humans, let alone evidence that might change the story of the peopling of the Americas. It sits a daunting 1000 meters above a valley, overlooking a desert landscape in the mountains north of Zacatecas. Getting there requires a 4- or 5-hour uphill scramble over a moonscape of jagged boulders.But in the soil below the cave's floor, a team led by archaeologist Ciprian Ardelean of the Autonomous University of Zacatecas, University City Siglo XXI, dug up almost 2000 stone objects that researchers think are tools. By combining state-of-the-art dating methods, the team argues that humans were at the site at least 26,000 years ago—more than 10,000 years before any other known human occupation in the region. “Chiquihuite is a solitary dot” of human occupation, Ardelean says.The dates place humans there during the height of the last ice age, when ice covered much of what is now Canada and sea levels were much lower. To have settled in Mexico by then, Ardelean says, people must have entered the Americas 32,000 years ago or more, before the ice reached its maximum extent.“If it is true people were in Zacatecas by 32,000 years ago, that changes everything—it more than doubles the time people have been in the Americas,” says Oregon State University, Corvallis, archaeologist Loren Davis, who was not part of the research team. But he remains skeptical, in part because he isn't convinced the artifacts are tools. “I'm not going to say it's impossible,” he says. “But if all they found are fractured rocks without any corroborating evidence, it's natural to be skeptical.”Still, he and others say they're willing to be convinced. For decades, most researchers thought humans arrived in the Americas approximately 13,000 years ago; occasional claims of an earlier arrival met strong criticism. But over the past decade, evidence for earlier migrations has emerged at sites from Canada to southern Chile. Most researchers now think people traveled by boat along North America's west coast, exploiting marine resources, as early as 16,000 years ago, when the interior of the continent was mostly frozen over (Science, 30 August 2019, p. 848).Just one other site—Bluefish Caves, in Canada's Yukon territory—has yielded dates as old as Chiquihuite. Researchers attribute thousands of broken animal bones there—dated to about 24,000 years ago—to human hunting. But the site remains controversial, in part because few stone tools or cut marks have been found among the bones.Ardelean heard about the cave from local villagers. Beginning in 2012, he and his team spent 1 month or more at a time at Chiquihuite, resupplying every few weeks using donkeys. Although forbidding today, the site would have looked far more hospitable 26,000 years ago. A spring-fed creek flows near the cave's original entrance, which was blocked long ago by rockslides. DNA and other evidence the researchers extracted from inside the cave show it opened onto a lush landscape harboring cranes, condors, marmot, goat, sheep, horses, and bears. “It looked a lot more like British Columbia or Oregon than desert,” Ardelean says.Digging into the cave floor over the past 8 years, Ardelean and his team found stones shaped into what look like scrapers, hand axes, spear points, and other tools at depths of up to 3 meters. Dating experts at the University of Oxford, the University of New South Wales (UNSW), and elsewhere determined when the rocks had last been exposed to light and radiocarbon-dated more than 50 samples of animal bone and charcoal found near the tools. As the group reports in Nature this week, the artifacts were deposited starting 26,000 years ago, and accumulated on the cave floor for the next 16,000 years. The authors argue that it adds up to a continuous human presence, with people regularly visiting the cave over millennia.But the team found no human DNA or bones cutmarked by human hands. Nor did they discover a central hearth, so they can't be certain whether the bits of burned wood analyzed for radiocarbon dates are from windblown wildfires or humanmade campfires. “The evidence is what the evidence is,” says team member Lorena Becerra-Valdivia, a radiocarbon dating expert at UNSW. “We're quite confident that the stone tools are, indeed, stone tools.”Critics point out that the tools are simple and don't resemble other toolkits from the Americas, raising the possibility they're the product of natural breakage. “They look like they could be artifacts, but why aren't they found anywhere else in the landscape?” wonders David Meltzer, an archaeologist at Southern Methodist University. The tools' consistency is also remarkable, he says. “If these tools are real, why are they only found—so far at least—in this one spot over a 10,000-year period? Humans adapt and adopt new technology.”Becerra-Valdivia says work in other sites, especially those south of the United States, may turn up corroborating evidence. “We need to take a really good look at South America.”And Ardelean says Chiquihuite has more secrets to reveal: “This is not a hit-and-run discovery. There's more evidence coming.”Cycil, L.M., DasSarma, S., Pecher, W., McDonald, R., AbdulSalam, M., Hasan, F., 2020. Metagenomic insights into the diversity of halophilic microorganisms indigenous to the Karak salt mine, Pakistan. Frontiers in Microbiology 11, :1567. doi: 10.3389/fmicb.2020.01567. regions are terrestrial analogs of the Earth’s primitive ecosystem and extraterrestrial environment. The salt range in Pakistan is considered among a few of the ancient salt deposits in the subcontinent. Karak salt mine is situated at the Northwest end in Pakistan. Despite the fact that halophiles initiated the formation of terrestrial ecosystems, their products and identities remain hidden. Some preliminary studies limited to culture-dependent isolations have been reported. Characterizing the microbiome that spans over centuries of ecosystem development is crucial, given their role in shaping landscape succession and biogeochemical cycles. Here, we used metagenomics techniques to explore the microbial diversity of the Karak salt mine. We used 16S rRNA Illumina amplicon sequencing to characterize the halophilic communities entrapped in Karak mine. The results were interpreted using Illumina Basespace, QIIME, and Cytoscape. Cultures were isolated at 16–25% salinity. Metagenomics data was consistent with our preliminary culturing data, indicating remarkable species to strain-level diversity of unique halophiles. A total of 107,099 (brine) and 122,679 (salt) reads were obtained. 16S rRNA based sequencing revealed a microbiome with bacteria (66% brine and 72% salt) dominated by Bacteroidetes and Proteobacteria with a strikingly high abundance of Archaea (18% brine and 13% salt). Alpha diversity has higher values in salt than in the brine. The study of the halophiles in the Karak salt mine provides clues for species contributing to the maintenance of biogeochemical cycles of the ecosystem. This is the first report of a metagenomic study of any hypersaline region of Pakistan.Da Silva, M.P., Kaesler, J.M., Reemtsma, T., Lechtenfeld, O.J., 2020. Absorption mode spectral processing improves data quality of natural organic matter analysis by Fourier-transform ion cyclotron resonance mass spectrometry. Journal of the American Society for Mass Spectrometry 31, 1615-1618. organic matter (NOM) plays an important role in elemental cycles and ecology. Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) is an ultrahigh resolution technique used to molecularly resolve the complexity of NOM mixtures. However, even the very high mass resolution of FT-ICR-MS may result in multiple formula assignments to peaks in an NOM spectrum, especially at the high mass-to-charge ratio (m/z). The absorption mode is one option to process raw FT-ICR-MS data that can further increase the resolution of the peaks and has not been widely applied in NOM studies. In this study, we show the advantages of using the absorption mode for the analysis of NOM samples using a reference sample (Suwannee River fulvic acid). The absorption mode increased the precision of peak detection as well as the number (+23%) and accuracy of formula assignment (by 28%) when compared to the magnitude mode, besides achieving three times higher resolution. The results presented here highlight the potential to reduce the error threshold used during molecular formula assignment. In conclusion, the absorption mode shows advantages in the processing of NOM samples and other complex mixtures and should be promoted in the NOM community.Dam, H.T., Vollmers, J., Sobol, M.S., Cabezas, A., Kaster, A.-K., 2020. Targeted cell sorting combined with single cell genomics captures low abundant microbial dark matter with higher sensitivity than metagenomics. Frontiers in Microbiology 11, 1377. doi: 10.3389/fmicb.2020.01377. members of environmental microbial communities are often overlooked and unexplored, primarily due to the lack of techniques capable of acquiring their genomes. Chloroflexi belong to one of the most understudied phyla, even though many of its members are ubiquitous in the environment and some play important roles in biochemical cycles or biotechnological applications. We here used a targeted cell-sorting approach, which enables the selection of specific taxa by fluorescent labeling and is compatible with subsequent single-cell genomics, to enrich for rare Chloroflexi species from a wastewater-treatment plant and obtain their genomes. The combined workflow was able to retrieve a substantially higher number of novel Chloroflexi draft genomes with much greater phylogenetical diversity when compared to a metagenomics approach from the same sample. The method offers an opportunity to access genetic information from rare biosphere members which would have otherwise stayed hidden as microbial dark matter and can therefore serve as an essential complement to cultivation-based, metagenomics, and microbial community-focused research approaches.Darin, A.V., Rogozin, D.Y., Meydus, A.V., Babich, V.V., Kalugin, I.A., Markovich, T.I., Rakshun, Y.V., Darin, F.A., Sorokoletov, D.S., Gogin, A.A., Senin, R.A., Degermendzhi, A.G., 2020. Traces of the Tunguska Event (1908) in sediments of Zapovednoe Lake based on SR–XRF data. Doklady Earth Sciences 492, 442-445. anomalous layer enriched with chemical elements indicating the presence of terrigenous matter was discovered in the sediment core of Zapovednoe Lake located 60 km from the epicenter of the Tunguska event (1908) using synchrotron radiation X-ray fluorescence spectroscopy (SR–XRF). Radioisotope measurements indicate that the age of the layer is consistent with the date of the catastrophe. Apparently, the anomalous layer was formed as a result of an intense terrigenous matter inflow from the water catchment area due to massive forest falls and subsequent wildfires caused by the Tunguska event. Thus, it is established that targeted searches for microparticles of extraterrestrial origin can be carried out in the discovered and dated anomalous bottom sediment layer.Datta, P., Tiwari, P., Pandey, L.M., 2020. Oil washing proficiency of biosurfactant produced by isolated Bacillus tequilensis MK 729017 from Assam reservoir soil. Journal of Petroleum Science and Engineering 195, 107612. present study describes elaborately the isolation of a potential biosurfactant producing and crude oil degrading strains isolated from the reservoir soil of Assam oil reservoir field. The produced biosurfactant was chemically characterized for its applicability for the enhanced oil recovery applications in terms of wetting, interfacial tension (IFT) and oil washing. From the seven isolated strains, Bacillus tequilensis MK 729017 was chosen based on the better surface active properties as it reduced the surface tension to 30 ± 2 mN/m along with a moderate emulsification index of 66 ± 2%. The produced biosurfactant was chemically identified to be lipopeptide, surfactin with a lower critical micelle concentration value of 90 mg/L. The carbon source and environmental parameters were optimized for the maximum concentration of the biosurfactant using response surface methodology based on the central composite design (RSM-CCD). The maximum biosurfactant concentration was measured to be 7.46 ± 0.39 g/L and YPS was determined as 0.45. The specific growth rate of the isolate was 0.15 ± 0.01 h?1 and YXS was estimated as 0.1. The produced biosurfactant was also found to be thermal and colloidal stable. The biosurfactant solutions altered wettability of hydrophobic rock surface from 90 ± 1° to 26 ± 1° indicating a better interfacial interaction. The IFT of the produced biosurfactant was found to be 0.32 ± 0.02 mN/m. The oil washing efficiency (80 ± 2%) of the produced surfactin was comparable with chemical surfactants and the process involved two-step: initial a faster (surface) washing followed by a slower (internal) washing. The first process was dependent on micelle sizes, while the latter was dependent on water-oil emulsion size. The lower emulsion size of surfactin contributed to a greater internal washing as compared to chemical surfactants.Davis, M.C., 2020. Temporal and spatial mediated changes in subsurface microbial community assemblages and functions. Biogeosciences Discussions 2020, 1-15. ecosystems can host different habitats with unique microbial assemblages and functions. Although groundwater microbes are important to subsurface processes, little is known about the drivers of change in these communities. Illumina sequencing and bioinformatic tools were used to examine whether different groundwater zones could have the same patterns of microbial community change over a two-year period. Five different groundwater zones from Hospital Hole, a stratified sinkhole in west-central Florida, were used in this study since they have been previously shown to host distinct microbial communities. Seasonal patterns of microbial community assemblages and potential metabolic functions were not identified in the sinkhole communities. Different physicochemical parameters correlated to microbial community change within each zone. Local hydrogeology appears to play an important role in subsurface microbial community change since Hurricane Irma and seasonal turnover events did not appear to cause a large perturbation in the microbial communities. Nutrient availability and local hydrogeochemistry appear to be important drivers of microbial community change in the subsurface.de Graaf, S., Vonhof, H.B., Weissbach, T., Wassenburg, J.A., Levy, E.J., Kluge, T., Haug, G.H., 2020. A comparison of isotope ratio mass spectrometry and cavity ring-down spectroscopy techniques for isotope analysis of fluid inclusion water. Rapid Communications in Mass Spectrometry 34, e8837.: Online oxygen (δ 18O) and hydrogen (δ 2H) isotope analysis of fluid inclusion water entrapped in minerals is widely applied in paleo‐fluid studies. In the state of the art of fluid inclusion isotope research, however, there is a scarcity of reported inter‐technique comparisons to account for possible analytical offsets. Along with improving analytical precisions and sample size limitations, interlaboratory comparisons can lead to a more robust application of fluid inclusion isotope records. Methods: Mineral samples—including speleothem, travertine, and vein material—were analyzed on two newly setup systems for fluid inclusion isotope analysis to provide an inter‐platform comparison. One setup uses a crusher unit connected online to a continuous‐flow pyrolysis furnace and an isotope ratio mass spectrometry (IRMS) instrument. In the other setup, a crusher unit is lined up with a cavity ring‐down spectroscopy (CRDS) system, and water samples are analyzed on a continuous standard water background to achieve precisions on water injections better than 0.1‰ for δ 18O values and 0.4‰ for δ 2H values for amounts down to 0.2?μL. Results: Fluid inclusion isotope analyses on the IRMS setup have an average 1σ reproducibility of 0.4‰ and 2.0‰ for δ 18O and δ 2H values, respectively. The CRDS setup has a better 1σ reproducibility (0.3‰ for δ 18O values and 1.1‰ for δ 2H values) and also a more rapid sample throughput (<30?min per sample). Fluid inclusion isotope analyses are reproducible at these uncertainties for water amounts down to 0.1?μL on both setups. Fluid inclusion isotope data show no systematic offsets between the setups. Conclusions: The close match in fluid inclusion isotope results between the two setups demonstrates the high accuracy of the presented continuous‐flow techniques for fluid inclusion isotope analysis. Ideally, experiments such as the one presented in this study will lead to further interlaboratory comparison efforts and the selection of suitable reference materials for fluid inclusion isotopes studies.de la Vega, E., Chalk, T.B., Wilson, P.A., Bysani, R.P., Foster, G.L., 2020. Atmospheric CO2 during the Mid-Piacenzian Warm Period and the M2 glaciation. Scientific Reports 10, 11002. Piacenzian stage of the Pliocene (2.6 to 3.6?Ma) is the most recent past interval of sustained global warmth with mean global temperatures markedly higher (by ~2–3?°C) than today. Quantifying CO2 levels during the mid-Piacenzian Warm Period (mPWP) provides a means, therefore, to deepen our understanding of Earth System behaviour in a warm climate state. Here we present a new high-resolution record of atmospheric CO2 using the δ11B-pH proxy from 3.35 to 3.15 million years ago (Ma) at a temporal resolution of 1 sample per 3–6 thousand years (kyrs). Our study interval covers both the coolest marine isotope stage of the mPWP, M2 (~3.3?Ma) and the transition into its warmest phase including interglacial KM5c (centered on ~3.205?Ma) which has a similar orbital configuration to present. We find that CO2 ranged from 389 +38 ?8 389?8+38ppm to 331 +13 ?11 , 331?11+13,ppm, with CO2 during the KM5c interglacial being 371 +32 ?29 371?29+32ppm (at 95% confidence). Our findings corroborate the idea that changes in atmospheric CO2 levels played a distinct role in climate variability during the mPWP. They also facilitate ongoing data-model comparisons and suggest that, at present rates of human emissions, there will be more CO2 in Earth’s atmosphere by 2025 than at any time in at least the last 3.3 million years.de Santana, C.O., Spealman, P., Melo, V.M.M., Gresham, D., de Jesus, T.B., Chinalia, F.A., 2020. Differential analysis of prokaryotic communities from pristine mangrove tidal zone sediments reveal distinct structures and functional profiles. Biogeosciences Discussions 2020, 1-35. forests are intertidal ecosystems that constitute a large portion of the world's coastline, as such, they are composed of, and reliant upon, microhabitats defined by the tides. However, we are only beginning to understand tidal microhabitat biodiversity and their role in nutrient cycling. The majority of metagenomic studies have so far been conducted on anthropogenically impacted areas. As even mild disruption can severely alter ecosystems and lead to decreased biodiversity and local extinctions, this is a critical issue. Here, we characterize prokaryotic populations and their involvement in nutrient cycling across the tidal zones of a pristine mangrove forest within a Brazilian Environmental Protection Area of the Atlantic Forest. We hypothesize that tidal zones in pristine mangroves constitute distinct microhabitats, are composed of different prokaryotic communities and, consequently, distinct functional profiles. Samples were collected in triplicate from zones below, between, and above the tidal waterline. Using 16S amplicon sequencing, we find significantly different prokaryotic communities with diverse nutrient cycling related functions, as well specific taxa with varying contribution to functional abundances between zones. Our findings contrast those observed in anthropogenically impacted mangroves and suggest that some aspects of mangrove zonation may be compromised by human activity.Dehghanizadeh, M., Cheng, F., Jarvis, J.M., Holguin, F.O., Brewer, C.E., 2020. Characterization of resin extracted from guayule (Parthenium argentatum): A dataset including GC-MS and FT-ICR MS. Data in Brief 11, 105989. (Parthenium argentatum), a shrub native to the arid region of the U.S. southwest and Mexico belonging to the Asteraceae family, is a source of high quality, hypoallergenic natural rubber with applications in pharmaceutical, tire, and food industries. Production of rubber results in a substantial amount of resin-containing residues which contain a wide variety of secondary metabolites (sesquiterpene esters, triterpene alcohols, fatty acids, etc.). In order to enhance the economic viability of guayule as an industrial crop, value-added use of the residues is needed and has the potential to reduce gross rubber production costs. The main objective of this research is the characterization of guayule resin using rapid and accurate analytical techniques to identify compounds of potential commercial value. Guayule resin is inherently complex and includes many high-molecular-weight and non-volatile compounds that are not easy to observe using traditional chromatographic techniques. The combination of two mass spectroscopy techniques: gas chromatography mass spectroscopy (GC-MS) and high-resolution Fourier transform ion cyclotron resonance mass spectroscopy (FT-ICR MS), were used to characterize the composition of the extracted resin from guayule (Parthenium argentatum). FT-ICR MS was used to characterize hundreds of compounds with over a wide range of molecular weights and degrees of aromaticity at higher levels of mass accuracy than other forms of mass spectrometry. GC-MS was used to identify volatile compounds like mono- and sesquiterpene compounds.Deirmendjian, L., Lambert, T., Morana, C., Bouillon, S., Descy, J.-P., Okello, W., Borges, A.V., 2020. Dissolved organic matter composition and reactivity in Lake Victoria, the world’s largest tropical lake. Biogeochemistry 150, 61-83. report a data set of dissolved organic carbon (DOC) concentration and dissolved organic matter (DOM) composition (stable carbon isotope signatures, absorption and fluorescence properties) obtained from samples collected in Lake Victoria, a large lake in East Africa. Samples were collected in 2018–2019 along a bathymetric gradient (bays to open waters), during three contrasting seasons: long rainy, short rainy and dry, which corresponded to distinctly water column mixing regimes, respectively, stratified, semi-stratified and mixed regimes. Eight DOM components from parallel factor analysis (PARAFAC) were identified based on three-dimensional excitation–emission matrices (EEMs), which were aggregated into three main groups of components (microbial humic-like, terrestrial humic-like, protein-like). Spatially, the more productive bays were characterized by higher DOM concentration than deeper more offshore waters (fluorescence intensity and DOC were?~?80% and?~?30% higher in bays, respectively). Seasonally, the DOM pool shifted from protein-like components during the mixed regime to microbial humic-like components during the semi-stratified regime and to terrestrial humic-like components during the stratified regime. This indicates that pulses of autochthonous DOM derived from phytoplankton occurred when the lake was mixing, which increased the availability of dissolved inorganic nutrients. Subsequently, this freshly produced autochthonous DOM was microbially processed during the following semi-stratified regime. In the open waters, during the stratified regime, only terrestrial refractory DOM components remained because the labile and fresh stock of DOM created during the preceding mixed season was consumed. In the bays, the high terrestrial refractory DOM during the stratified regime may be additionally due to the allochthonous DOM input from the runoff. At the scale of the whole lake, the background refractory DOM probably comes mainly from precipitation and followed by river inputs.Demicco, R.V., Lowenstein, T.K., 2020. When “evaporites” are not formed by evaporation: The role of temperature and pCO2 on saline deposits of the Eocene Green River Formation, Colorado, USA. GSA Bulletin 132, 1365-1380. precipitates in the Dead Sea during winter but re-dissolves above the thermocline upon summer warming, “focusing” halite deposition below the thermocline (Sirota et al., 2016, 2017, 2018). Here we develop an “evaporite focusing” model for evaporites (nahcolite + halite) preserved in a restricted area of the Eocene Green River Formation in the Piceance Creek Basin of Colorado, USA. Nahcolite solubility is dependent on partial pressure of carbon dioxide (pCO2) as well as temperature (T), so these models covary with both T and pCO2. In the lake that filled the Piceance Creek Basin, halite, nahcolite or mixtures of both could have precipitated during winter cooling, depending on the CO2 content in different parts of the lake. Preservation of these minerals occurs below the thermocline (>～25 m) in deeper portions of the basin. Our modeling addresses both: (1) the restriction of evaporites in the Piceance Creek Basin to the center of the basin without recourse to later dissolution and (2) the variable mineralogy of the evaporites without recourse to changes in lake water chemistry. T from 20 to 30 °C and pCO2 between 1800 and 2800 ppm are reasonable estimates for the conditions in the Piceance Creek Basin paleolake. Other evaporites occur in the center of basins but do not extend out to the edges of the basin. Evaporite focusing caused by summer-winter T changes in the solubility of the minerals should be considered for such deposits and variable pCO2 within the evaporating brines also needs to be considered if pCO2 sensitive minerals are found.Deng, Q., Zhang, T., Zhao, F., Wang, H., Yin, J., 2020. The influence of hydrogeology to generation of hydrogen sulfide of low-rank coal in the southeast margin of Junggar Basin, China. Geofluids 2020, 8859100. salinity, chemical properties, and migration characteristics of groundwater in coal measures are the key factors that affect the generation, migration, and reservoir of hydrogen sulfide (H2S) in low-rank coal seams. Taking the Jurassic coal and rock strata in the southeastern margin of the Junggar basin as the research object, according to the hydrogeological characteristics of the coal measures, the region is divided into 4 hydrogeological units. The coalbed methane contains a large number of secondary biogas. Along the direction of groundwater runoff, the salinity and the pH value increase gradually. The salinity in the hydrogeological units is low; it is not conducive to the propagation of sulfate-reducing bacteria and the formation of hydrogen sulfide of the Houxia, the south of Manasi River, and Hutubi and Liuhuangou area, the western region of the Miquan. The high salinity center and depressions of low water level (hydrodynamic stagnation zone) in the hydrogeological unit of the Liuhuanggou and the Miquan are the main areas for the production and enrichment of H2S in the low-rank coal. The high salinity in water is formed by infiltration, runoff, and drought evaporation. At the same time, the deep confined water environment closed well; in conditions of hydrocarbon-rich, under the action of sulfate-reducing bacteria, bacterial sulfate reduction will occur and hydrogen sulfide formed. According to the circulation characteristics of water bearing H2S in the region, imbricate and single bevel two kind generation and enrichment mode of hydrogen sulfide under the action of hydrodynamic control. The solubility of hydrogen sulfide in pure water and solutions of NaCl and Na2SO4 with different molar concentrations was calculated. The H2S solubility of groundwater in coal measures of 4 hydrogeological units was estimated.Deschamps, F., Mottez, F., 2020. From cosmic explosions to terrestrial fires? A discussion. The Journal of Geology 128, 389-391. of: Melott, A. L., and Thomas, B. C. 2019. From cosmic explosions to terrestrial fires? J. Geol. 127:475–481.Replyed to: Melott, A.L., Thomas, B.C., 2020. From cosmic explosions to terrestrial fires? A reply. The Journal of Geology 128, 393-393.Several observational studies have revealed the explosion of a supernova in the early Pleistocene at about 100 pc from the Solar System. The proof of this explosion is based on the signature associated with Fe60 deposits in Earth’s sediments and on the Moon’s regolith. The supernova remnant was the cause of additional input of galactic cosmic rays (GCRs) in the Solar System. Their propagation from the supernova remnant to Earth and the effects of the associated cascades of secondary particles triggered by their interaction with Earth’s atmosphere were analyzed by Melott and Thomas (2019). According to their study and previous works cited in their article, high-energy cosmic rays (above 1 TeV) caused a 20-fold increase of irradiation by muons on Earth’s surface and on the ocean and an order of magnitude increase of the atmospheric ionization that could have lasted more than 1,000 years. The increase in irradiation could have contributed to a minor mass extinction in the Pliocene–Pleistocene transition, 2.6 My ago. Melott and Thomas (2019) analyzed the climatic consequences of the increased atmospheric ionization leading to more frequent lightning and, therefore, to an increase in nitrate deposition and in wildfires. Increased wildfires, evidenced by an increase in soot and carbon deposits over the relevant period, would have contributed to the transition from forest to savanna in northeastern Africa, long argued to have been a factor in the evolution of hominin bipedalism.In this discussion, we argue that the Gauss-Matuyama Earth’s magnetic field reversal, which defines the Pliocene–Pleistocene transition (Suc et al. 1997), could have enhanced the impact of the GCRs related to the early Pleistocene supernova discussed by Melott and Thomas (2019).Although they discussed various hypotheses concerning the interstellar magnetic field, they voluntarily neglected the variations of local magnetic fields on the impact of cosmic rays. They base their choice on a work by Jackman et al. (2016) in which the effect of GCRs on atmospheric chemistry is analyzed during the 1960–2010 epoch. More specifically, Jackman et al. (2016) showed that local magnetic field fluctuations of a factor of two at Earth’s poles over a solar cycle only have a moderate effect. These conclusions are correct only if Earth’s magnetic field has a dominant dipole component, as is the case in the present epoch analyzed in Jackman et al. (2016) and during most of Earth’s history. By contrast, they certainly do not apply to geomagnetic excursions and magnetic field polarity reversals, which have episodically affected Earth’s magnetic field. Paleomagnetic studies show that these events are usually short (a few thousand years) compared with the geological timescale and have occurred many times in the past but not periodically. Most importantly for our discussion, during these events, the shielding provided by the magnetic field is lost, thus potentially increasing the impact of GCRs on the biosphere.Magnetic field reversals and geomagnetic excursions are complex events during which the dipolar component of the magnetic field is unstable and weak (e.g., Glatzmaier and Coe 2015). In most if not all reversals, the intensity of the dipole is strongly reduced. In addition, some reversals show complex directional changes; that is, the locations of the (virtual) geomagnetic poles change rapidly, and the polarity may swing several times before settling to normal or reverse. The whole process may last several thousand years and in some cases up to 20,000 years.The reduction in magnetic field intensity and the rapid changes in the direction of the dipole have important consequences on the propagation of charged particles. Low-energy cosmic rays are partly guided by magnetic field lines and, with the present dipole magnetic field that is implicitly supposed in Melott and Thomas (2019), the ratio of ionospheric ionization at the poles and at the equator is almost one order of magnitude (Jackman et al. 2016, fig. 1). When the dipole field was reduced or canceled or when the virtual poles were located at low or intermediate latitudes, the intertropical zone, where African savanna is situated, could have been exposed to the direct influx of cosmic rays as the poles are today.The Gauss-Matuyama magnetic field reversal is used to define the boundary between the Pliocene and Pleistocene epochs (Suc et al. 1997) and has been dated to 2.589 ± 0.003 Ma based on lacustrine sediments (Deino et al. 2006). This age is compatible with the age of the supernova and associated Fe60 deposits as discussed previously. Although the Gauss-Matuyama reversal has been dated precisely, paleomagnetic studies indicate that the magnetic field has been unstable for more than 10 ky around this date. For instance, Glen et al. (1999) reported fluctuations of the magnetic field direction indicating a total transition time of about 15 ky. Yang et al. (2014) made similar observations from samples collected in a different region and concluded that the transition lasted more than 11 ky. Also worthy of interest, Goguitchaichvili et al. (1999) estimated that, during the Gauss-Matuyama transition, the intensity of the magnetic field in southwestern Iceland was on average 14.8 ± 4.6 μT (compared with 52.1 μT today), corresponding to a decrease of the magnetic dipole moment by a factor of two. Therefore, during the Gauss-Matuyama transition, the biosphere may have been unprotected from cosmic rays for 10–15 ky.The increased input of GCRs associated with a supernova may also last for a few thousand years (Brahimi et al. 2020). The impacts of the arrival of supernova GCRs and the magnetic field reversal can be combined if the two phenomena occurred at the same time, as might have been the case 2.6 My ago. The possible effect of the partial or total cancellation of Earth’s magnetic dipole component during the Gauss-Matuyama magnetic reversal could thus be included in further work following the study by Melott and Thomas (2019). This effect would most probably reinforce their conclusion regarding the impact of the supernova occurring 2.6 My ago as a possible cause of the Pliocene–Pleistocene transition.Addendum: We acknowledge authors A. L. Melott and B. C. Thomas for their answer, and we agree with their argument that the highly energetic particles studied in their article are not influenced by the geomagnetic field deflection. We still consider that the increase of the lower-energy GCRs (abundant, e.g., in cases A and C in Thomas et al. [2016]), which are influenced by Earth’s magnetic field, may have enhanced the cloud cover. Empirical studies show the influence of the lower-energy GCRs (those below 20 GeV measured with neutron monitors) on the cloud cover (Svensmark 1998; Harrison and Stephenson 2006). This finding is complementary to the process described in Melott and Thomas’s article with higher-energy cosmic rays, and it reinforces the conclusions regarding the influence of a nearby supernova as a trigger of a cooling of the climate and wildfires. As for other geological events, the Pliocene–Pleistocene transition may result from an addition of independent causes with similar consequences.References Cited Brahimi, L.; Marcowith, A.; and Ptuskin, V.-S. 2020. Nonlinear diffusion of cosmic rays escaping from supernova remnants: cold partially neutral atomic and molecular phases. Astron. Astrophys. 633:A72.Deino, A. L.; Kingston, J. D.; Glen, J. M.; Edgar, R. K.; and Hill, A. 2006. Precessional forcing of lacustrine sedimentation in the late Cenozoic Chemeron Basin, Central Kenya rift, and calibration of the Gauss/Matuyama boundary. Earth Planet. Sci. Lett. 247:41–60. Glatzmaier, G. A., and Coe, R. S. 2015. Magnetic polarity reversal in the core. In Schubert, G., ed. Treatise of geophysics (2nd ed., Vol. 8). Oxford, Elsevier, p. 279–295.Glen, J. M. G.; Coe, R. S.; and Liddicoat, J. C. 1999. A detailed record of paleomagnetic field change from Searles Lake, California: 2. The Gauss/Matuyama polarity reversal. J. Geophys. Res. 104:12,883–12,894.Goguitchaichvili, A.; Prévot, M.; Thompson, J.; and Roberts, N. 1999. An attempt to determine the absolute geomagnetic field intensity in southwestern Iceland during the Gauss-Matuyama reversal. Phys. Earth Planet. Inter. 115:53–66. Harrison, R. G., and Stephenson, D. B. 2006. Empirical evidence for a nonlinear effect of galactic cosmic rays on clouds. Proc. R. Soc. A 462(2068):1221–1233. Jackman, C. H.; Marsh, D. R.; Kinnison, D. E.; Mertens, C. J.; and Fleming, E. L. 2016. Atmospheric changes caused by galactic cosmic rays over the period 1960–2010. Atmos. Chem. Phys. 16(9):5853–5866.Melott, A. L., and Thomas, B. C. 2019. From cosmic explosions to terrestrial fires? J. Geol. 127:475–481.Suc, J.-P.; Bertini, A.; Leroy, S. A. G.; and Suballyova, D. 1997. Towards the lowering of the Pliocene/Pleistocene boundary to the Gauss-Matuyama reversal. Quat. Int. 40:37–42.Svensmark, H. 1998. Influence of cosmic rays on Earth’s climate. Phys. Rev. Lett. 81:5027. Thomas, B. C.; Engler, E. E.; Kachelrie?, M.; Melott, A. L.; Overholt, A. C.; and Semikoz, D. V. 2016. Terrestrial effects of nearby supernovae in the early Pleistocene. Astrophys. J. Lett. 826:L3.Yang, T. S.; Hyodo, M.; Yang, Z. Y.; Zhang, S. H.; Mishima, T.; Wu, H. C.; Li, H. Y.; et al. 2014. High-frequency polarity swings. Sci. China Earth Sci. 57:1929–1943. Desmau, M., Carboni, A., Le Bars, M., Doelsch, E., Benedetti, M.F., Auffan, M., Levard, C., Gelabert, A., 2020. How microbial biofilms control the environmental fate of engineered nanoparticles? Frontiers in Environmental Science 8, 82. doi: 10.3389/fenvs.2020.00082. the fate of engineered nanoparticles (ENPs) once they are released in the environment is essential to evaluate their impacts to ecosystems. Microbial biofilms, as highly reactive compartments in soils and sediments, have the potential to impose strong controls on ENPs life cycle in natural settings. However, information regarding impacts of biofilms toward ENPs environmental fate are not easily accessible, and such evidences are collected and discussed in this review, in order to identify common trends and to better constrain the role played by these microbial structures. Biofilms are reported to exhibit important ENPs accumulation capacities, and short to long-term ENPs immobilization can thus be expected. Mechanisms that govern such accumulation and ENPs migration within biofilms depend strongly on electrostatic and hydrophobic interactions, as well as biofilm structural properties, such as density and permeability. They are a combination of key parameters that include ENPs size and surface properties, mineral substrate reactivity, ability to develop organic corona around ENPs, or formation of aggregates within the biofilm thickness. In addition, these microbial structures exhibit highly reactive microenvironments, and are consequently able to impose major ENPs transformations such as dissolution, through ligand- or redox-mediated pathways, as well as passivation or stabilization processes. Interestingly, exposure to toxic ENPs can even trigger a response from micro-organisms biofilms which has the potential to strongly modify ENPs speciation. Promising approaches to investigate the role of microbial biofilms for ENPs cycling in realistic systems are introduced through the use of mesocosms, medium-size replicated ecosystems that allow to integrate the complexity of natural settings. Finally, biofilm-mediated nanoparticles synthesis in man-impacted systems is presented. This raises important questions regarding biofilms role as secondary sources of nanoparticles.Dessandier, P.-A., Borrelli, C., Yao, H., Sauer, S., Hong, W.-L., Panieri, G., 2020. Foraminiferal δ18O reveals gas hydrate dissociation in Arctic and North Atlantic ocean sediments. Geo-Marine Letters 40, 507-523. investigations in the Arctic and north Atlantic are crucial to understanding past and current climate change, in particular considering amounts of pressure-temperature sensitive gas stored in marine sediments of the region. Many paleoceanographic studies are based on foraminiferal oxygen and carbon stable isotope compositions (δ18O, δ13C) from either planktonic specimens, benthic specimens or both. However, in seafloor regions promixal to high upward methane fluxes, such as where seafloor gas emission and shallow gas hydrate-bearing sediment occur, foraminiferal δ18O and δ13C display a wide range of values. Our study focuses on foraminiferal stable isotope signatures in shallow sediment at core sites in the Arctic and North Atlantic affected by significant upward flow of methane. This includes cores with shallow sulfate methane transitions that are adjacent to seeps and containing gas hydrate. We place emphasis on potential effects due to gas hydrate dissociation and diagenesis. Gas hydrate dissociation is known to increase pore-water δ18O, but our results indicate that precipitation of methane-derived authigenic carbonate (MDAC) also affects the foraminiferal δ18O of both planktonic and benthic species. In addition to this post-depositional overprint, we investigate the potential bias of the stable isotope record due to ontogenetic effects. Our data show that the size fraction does not impact the isotopic signal of planktonic and benthic foraminifera.Deville, E., Scalabrin, C., Jouet, G., Cattaneo, A., Battani, A., Noirez, S., Vermesse, H., Olu, K., Corbari, L., Boulard, M., Marsset, T., Dall'Asta, M., Torelli, M., Pastor, L., Pierre, D., Loubrieu, B., 2020. Fluid seepage associated with slope destabilization along the Zambezi margin (Mozambique). Marine Geology 428, 106275. for active fluid seepages have been discovered along the Zambezi continental slope (offshore Southern Mozambique). These seepages are mostly associated with pockmarks which are aligned along a trend parallel to the slope and running closely upstream of the headwall scarp of a wide zone of slope destabilization. Fluid seepages are interpreted as a potential trigger for the slope destabilization. Acoustic anomalies within the water column have been interpreted as related to moderate bubble seepages mostly located outside and only punctually inside the destabilization zone. Exploration with the SCAMPI towed camera system in the widest pockmark (diameter 200 m wide) has shown fluid seepages associated to authigenic carbonate crusts and possibly bacterial mats. These fluid seepages are also associated to the presence of chemiosynthetic organisms (Vesicomyidae and Thyasiridae bivalves, Siboglinidae tubeworms). The sampled gas in the sediment corresponds mainly to CH4 of microbial origin, generated by hydrogenotrophic methanogenesis from a substrate of organic origin, i.e. a conventional process of genesis of microbial gas in the marine domain. No evidence for thermogenic gas was detected. Another type of pockmarks has been observed within the core of the slope destabilization zone. Most of these pockmarks are inactive in terms of fluid seepage at present time and are associated to carbonate buildups forming chimney geometries. They probably correspond to diagenetic chimneys of former fluid migration pathways that have been exhumed during the mass sliding and the surrounding depression are related to recurrent activity of strong lateral slope currents which have scoured the sediments around. The spatial organization of the slope destabilization features is considered as representative of the temporal evolution of the landslide giving information about the dynamics of slope instability processes. This proposed evolution started by scattered seepages of formation water with dissolved gas. Then free gas seepages appeared notably in the upper part of the slope. This was followed by progressive shallow deformation in the sediments downslope of the main gas seepages. Finally, the whole slope was destabilized forming imbricated landslides exhuming locally former diagenetic chimneys.Dinauer, A., Adolphi, F., Joos, F., 2020. Mysteriously high Δ14C of the glacial atmosphere: influence of 14C production and carbon cycle changes. Climate of the Past 16, 1159-1185. intense focus on the ～190?‰ drop in atmospheric Δ14C during Heinrich Stadial 1 at ～17.4–14.6?ka, the specific mechanisms responsible for the apparent Δ14C excess in the glacial atmosphere have received considerably less attention. The computationally efficient Bern3D Earth system model of intermediate complexity, designed for long-term climate simulations, allows us to address a very fundamental but still elusive question concerning the atmospheric Δ14C record: how can we explain the persistence of relatively high Δ14C values during the millennia after the Laschamp event? Large uncertainties in the pre-Holocene 14C production rate, as well as in the older portion of the Δ14C record, complicate our qualitative and quantitative interpretation of the glacial Δ14C elevation. Here we begin with sensitivity experiments that investigate the controls on atmospheric Δ14C in idealized settings. We show that the interaction with the ocean sediments may be much more important to the simulation of Δ14C than had been previously thought. In order to provide a bounded estimate of glacial Δ14C change, the Bern3D model was integrated with five available estimates of the 14C production rate as well as reconstructed and hypothetical paleoclimate forcing. Model results demonstrate that none of the available reconstructions of past changes in 14C production can reproduce the elevated Δ14C levels during the last glacial. In order to increase atmospheric Δ14C to glacial levels, a drastic reduction of air–sea exchange efficiency in the polar regions must be assumed, though discrepancies remain for the portion of the record younger than ～33?ka. We end with an illustration of how the 14C production rate would have had to evolve to be consistent with the Δ14C record by combining an atmospheric radiocarbon budget with the Bern3D model. The overall conclusion is that the remaining discrepancies with respect to glacial Δ14C may be linked to an underestimation of 14C production and/or a biased-high reconstruction of Δ14C over the time period of interest. Alternatively, we appear to still be missing an important carbon cycle process for atmospheric Δ14C.Djaoudi, K., Van Wambeke, F., Barani, A., Bhairy, N., Chevaillier, S., Desboeufs, K., Nunige, S., Labiadh, M., des Tureaux, T.H., Lefèvre, D., Nouara, A., Panagiotopoulos, C., Tedetti, M., Pulido-Villena, E., 2020. Experimental evidence of the potential bioavailability for marine heterotrophic bacteria of aerosols organic matter. Biogeosciences Discussions 2020, 1-24. surface ocean receives important amounts of organic carbon from atmospheric deposition. The degree of bioavailability of this source of organic carbon will determine its impact on the marine carbon cycle. In this study, the potential availability of dissolved organic carbon (DOC) leached from both desert dust and anthropogenic aerosols to marine heterotrophic bacteria was investigated. The experimental design was based on 16-days incubation, in the dark, of a marine bacterial inoculum into artificial seawater amended with water-soluble Saharan dust (D-treatment) and anthropogenic (A-treatment) aerosols, so that the initial DOC concentration leachate from aerosols is 36??M?C. Glucose-amended (G) and non-amended (control) treatments were run in parallel. Over the incubation period, an increase in bacterial abundance (BA) and bacterial production (BP) was observed first in the G-treatment, followed then by D and finally A treatments, with bacterial growth rates significantly higher in the G and D treatments than the A treatment. Following this growth, maxima of BP reached were similar in D (879?±?64?ng?C?L?1?h?1; n?=?3) and G (648?±?156?ng?C?L?1?h?1; n?=?3) treatments and were significantly higher than in A-treatment (124?±?39?ng?C?L?1?h?1; n?=?2). The DOC consumed over the incubation period was similar in A (9?±?4??M; n?=?2) and D (9?±?2??M; n?=?3) treatments and was significantly lower than that consumed in the G-treatment (22?±?3??M). Nevertheless, the bacterial growth efficiency (BGE) in the D treatment (14.2?±?5.5?%; n?=?3) compared well with the G treatment (7.6?±?2?%; n?=?3), suggesting that the metabolic use of the labile DOC fraction in both conditions was energetically equivalent. In contrast, the BGE in the A-treatment was lower (1.7?±?0.1?%; n?=?2), suggesting that the most part of used labile DOC was catabolized. The results obtained in this study highlight the potential of aerosol organic matter to sustain the metabolism of marine heterotrophs and stress the need to include this external source of organic carbon into biogeochemical models, for a better constraining of the carbon budget.Dommain, R., Andama, M., McDonough, M.M., Prado, N.A., Goldhammer, T., Potts, R., Maldonado, J.E., Nkurunungi, J.B., Campana, M.G., 2020. The challenges of reconstructing tropical biodiversity with sedimentary ancient DNA: A 2200-year-long metagenomic record from Bwindi Impenetrable Forest, Uganda. Frontiers in Ecology and Evolution 8, 218. doi: 10.3389/fevo.2020.00218. ancient DNA has been proposed as a key methodology for reconstructing biodiversity over time. Yet, despite the concentration of Earth’s biodiversity in the tropics, this method has rarely been applied in this region. Moreover, the taphonomy of sedimentary DNA, especially in tropical environments, is poorly understood. This study elucidates challenges and opportunities of sedimentary ancient DNA approaches for reconstructing tropical biodiversity. We present shotgun-sequenced metagenomic profiles and DNA degradation patterns from multiple sediment cores from Mubwindi Swamp, located in Bwindi Impenetrable Forest (Uganda), one of the most diverse forests in Africa. We describe the taxonomic composition of the sediments covering the past 2200 years and compare the sedimentary DNA data with a comprehensive set of environmental and sedimentological parameters to unravel the conditions of DNA degradation. Consistent with the preservation of authentic ancient DNA in tropical swamp sediments, DNA concentration and mean fragment length declined exponentially with age and depth, while terminal deamination increased with age. DNA preservation patterns cannot be explained by any environmental parameter alone, but age seems to be the primary driver of DNA degradation in the swamp. Besides degradation, the presence of living microbial communities in the sediment also affects DNA quantity. Critically, 92.3% of our metagenomic data of a total 81.8 million unique, merged reads cannot be taxonomically identified due to the absence of genomic references in public databases. Of the remaining 7.7%, most of the data (93.0%) derive from Bacteria and Archaea, whereas only 0–5.8% are from Metazoa and 0–6.9% from Viridiplantae, in part due to unbalanced taxa representation in the reference data. The plant DNA record at ordinal level agrees well with local pollen data but resolves less diversity. Our animal DNA record reveals the presence of 41 native taxa (16 orders) including Afrotheria, Carnivora, and Ruminantia at Bwindi during the past 2200 years. Overall, we observe no decline in taxonomic richness with increasing age suggesting that several-thousand-year-old information on past biodiversity can be retrieved from tropical sediments. However, comprehensive genomic surveys of tropical biota need prioritization for sedimentary DNA to be a viable methodology for future tropical biodiversity studies.Dozier, C.A., Kim, D., Russell, D.H., 2020. Chemical residue evidence in Leon Plain pottery from the Toyah phase (1300–1650 CE) in the American Southern Plains. Journal of Archaeological Science: Reports 32, 102450. remains from the Toyah Phase (1300-1650 CE), prior to Spanish colonization of the American Southern Plains in central and south Texas, suggest that foraging indigenous peoples maintained a feasting economy. Mind-altering beverages, such as caffeinated or alcoholic drinks, are a common attraction of feasts worldwide and throughout human history. Fifty-four sherds of Leon Plain ware from six archaeological sites were chemically analyzed using ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Six samples contained biomarkers suggestive of caffeinated beverage(s)—either black drink, Yaupon Holly (Ilex vomitoria) ceremonial tea, or chocolate, derived from cacao (Theobroma cacao or bicolor). Three of those six samples had duplicate results over three trials. Six different samples contained succinic and tartaric acid, sometimes associated with grape wine, but no samples maintained those results over two trials. These results suggest that Leon Plain may have sometimes been used to contain mind-altering substances, such as black drink.Du, Y., Mehmani, A., Xu, K., Kelly, S., Balhoff, M., Torres-Verdín, C., 2020. Microfluidic diagnostics of the impact of local microfracture connectivity on hydrocarbon recovery following water injection. Water Resources Research 56, e2019WR026944. Microfractures originate in hydrocarbon reservoirs and groundwater aquifers either in the form of pore-scale authigenic apertures or secondary openings during well stimulation. Microfractures are often difficult to detect and can act as an invisible impediment when predicting hydrocarbon recovery. We use microfluidics to identify the flow conditions at which microfracture connectivity with macrofractures becomes impactful. The analysis focuses on fluid displacements at unfavorable mobility ratios, which are difficult to capture with high-order numerical methods. Two configurations of microfracture type with the porous matrix, either dead-end (only connected to one macrofracture) or connecting two macrofractures, were investigated as case examples for both water and oil-wet conditions. Our findings confirm that improvements in hydrocarbon recovery are not universal due to the presence of microfractures but rather are a function of capillary number, wettability, and microfracture connectivity. We find that, regardless of wettability, a capillary number threshold for a connected microfractured system exists beyond which the effects of microfractures on recovery, fluid dendrite morphology, and oil ganglia number diminish considerably. However, substantial geometry-dependent differences in recovery are observed below this threshold. A connected microfracture generally decreases hydrocarbon recovery and suppresses coalescence of viscous fingering dendrites regardless of wettability. In contrast, a dead-end microfracture causes wettability-dependent effects with (1) minimal impact on hydrocarbon recovery at water-wet conditions and (2) both decreasing and increasing recovery effects at oil-wet conditions. Furthermore, dead-end microfractures become somewhat impactful to the divergence of viscous dendrites when capillary number increases but are overall ineffective to the trapped ganglia numbers.Dubois, L.M., Aczon, S., Focant, J.-F., Perrault, K.A., 2020. Translation of a one-dimensional to a comprehensive two-dimensional gas chromatography method with dual-channel detection for volatile organic compound measurement in forensic applications. Analytical Chemistry 92, 10091-10098. its introduction in the early 1990s, comprehensive two-dimensional gas chromatography (GC×GC) has evolved from a separation science research tool to the central component of many industries. Despite the maturity of the technique, some fields remain reluctant to its use in routine applications. In the case of forensic science, some constraints are the strict requirements enforced in forensic laboratories and the time and effort that must be invested for intralaboratory method validation. Concerns may also arise about whether information could be lost when transitioning to a new technique. This study reports on a method translation from conventional one-dimensional (1D) GC to GC×GC, ensuring the integrity of data as conversion is made. The GC was retrofitted with a reverse fill/flush (RFF) flow modulator and equipped with dual-channel detection using a quadrupole mass spectrometer (qMS) and a flame ionization detector (FID). The parallel use of two detectors, where qMS was applied for qualitative identification and FID for quantification, allowed higher flows and slightly wider peaks to be exploited for the analysis of a volatile organic compound (VOC) reference mixture relevant to forensic VOC profiling. Peak quality assessment and calibration curves using GC-qMS and GC×GC-qMS/FID document the transfer and adaptation of the original method without a loss in data quality. Furthermore, the preprocessing and the data analysis processing steps, including calibration and peak quality assessment for each of the three data sets, are explained in detail. This information provides benchmark data for routine laboratories that want to implement a GC×GC approach into routine workflows.Ducros, M., Nader, F.H., 2020. Map-based uncertainty analysis for exploration using basin modeling and machine learning techniques applied to the Levant Basin petroleum systems, Eastern Mediterranean. Marine and Petroleum Geology 120, 104560. Levant Basin of the East-Mediterranean region contains a biogenic petroleum system and possibly an underlying thermogenic system. The application of a new map-based uncertainty and sensitivity analysis that integrates a large set of geological parameters demonstrates that a connection between an Upper Cretaceous thermogenic petroleum system and the shallower Oligo-Miocene reservoirs is highly possible in the southern part of the basin (offshore Israel and southern Lebanon) where hydrocarbon fluids are generated from the Campanian source rock and charge the overlying Oligo-Miocene reservoir interval through faults. Estimates of volumes of expelled hydrocarbons combined with regional analysis of the Eocene top seal integrity indicates that the most prospective zones correspond to the southern offshore Lebanon and offshore Israel. In the northern part of the Levant Basin (offshore central and northern Lebanon), petroleum fluids potentially generated by the Campanian source rocks remain trapped under the Eocene seal or they migrate towards the margins of the basin. Our approach is based on applications of machine learning techniques and robust statistical analyses to petroleum systems modeling, focusing on spatial uncertainty analysis. It may be used on similar frontier or emerging hydrocarbon provinces to help de-risking the petroleum systems.Dunmore, C.J., Skinner, M.M., Bardo, A., Berger, L.R., Hublin, J.-J., Pahr, D.H., Rosas, A., Stephens, N.B., Kivell, T.L., 2020. The position of Australopithecus sediba within fossil hominin hand use diversity. Nature Ecology & Evolution 4, 911-918. human lineage is marked by a transition in hand use, from locomotion towards increasingly dexterous manipulation, concomitant with bipedalism. The forceful precision grips used by modern humans probably evolved in the context of tool manufacture and use, but when and how many times hominin hands became principally manipulative remains unresolved. We analyse metacarpal trabecular and cortical bone, which provide insight into behaviour during an individual’s life, to demonstrate previously unrecognized diversity in hominin hand use. The metacarpals of the palm in Australopithecus sediba have trabecular morphology most like orangutans and consistent with locomotor power-grasping with the fingers, while that of the thumb is consistent with human-like manipulation. This internal morphology is the first record of behaviour consistent with a hominin that used its hand for both arboreal locomotion and human-like manipulation. This hand use is distinct from other fossil hominins in this study, including A. afarensis and A. africanus.Ebert, M., Poelchau, M.H., Kenkmann, T., Schuster, B., 2020. Tracing shock-wave propagation in the Chicxulub crater: Implications for the formation of peak rings. Geology 48, 814-818. Chicxulub crater (Yucatán Peninsula, Mexico) is considered exceptional in many scientific aspects; morphologically it is the only known impact structure on Earth with a well-preserved peak ring. Recent drilling (International Ocean Discovery Program–International Continental Scientific Drilling Program Expedition 364) into this topographic feature provides insights into the structural properties and complex formation of a peak ring. By means of U-stage microscopy on shocked quartz grains from the granitic section of the recovered drill core, orientations of feather features (FFs) were determined and local principal axis of stress (σ1) orientations of the shock wave were derived. The FF orientations are strongly confined to a radially outward trend (WNW) relative to the crater center, which emphasizes a link between FF formation and the direction of shock-wave propagation. Thus, FFs represent an excellent tool as a stress-orientation indicator for the shock wave. Our microstructural data set shows that the granitic basement of the peak ring between ～750 and ～1200 m below seafloor behaved as a semi-coherent block above an imbricate thrust zone, and underwent both rotation and local folding during cratering. This validates the block sizes of acoustic fluidization employed in most Chicxulub-scale impact simulations. The folding of the upper part of the granitic basement may have developed by either (1) compression of the crater wall at the transient cavity and/or (2) dragging by the centripetal flow of the overlying crater material.Echavarri-Bravo, V., Tinzl, M., Kew, W., Cruickshank, F., Mackay, C.L., Clarke, D.J., Horsfall, L.E., 2019. High resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for the characterisation of enzymatic processing of commercial lignin. New Biotechnology 52, 1-8. and lignin components of woody biomass have been identified as an attractive alternative to fossil fuels. However, the complex composition of this plant polymer is one of the drawbacks that limits its exploitation. Biocatalysis of lignin to produce platform chemicals has been receiving great attention as it presents a sustainable approach for lignin valorisation. Aligned with this area of research, in the present study we have applied ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to identify the preferred lignin substrates of a ligninolytic enzyme, a laccase produced by the terrestrial fungus Trametes versicolor. A commercial lignin was incubated with the laccase and acetosyringone (a laccase mediator) for up to 168?h and direct infusion electrospray FT-ICR MS enabled the identification of thousands of molecular species present in the complex lignin sample at different incubation time points. Significant changes in the chemical composition of lignin were detected upon laccase treatment, which resulted in a decrease in the molecular mass distribution of assigned species, consistent with laccase lytic activity. This reduction was predominantly in species classified as lignin-like (based on elemental ratios) and polymeric in nature (>400?Da). Of particular note was a fall in the number of species assigned containing sulfur. Changes in the chemical composition/structure of the lignin polymer were supported by FT-IR spectroscopy. We propose the use of FT-ICR MS as a rapid and efficient technique to support the biotechnological valorisation of lignin as well as the development and optimization of laccase-mediator systems for treating complex mixtures.Editorial, 2020. Soil carbon unearthed. Nature Geoscience 13, 523. store vast quantities of carbon and have the potential to help mitigate or exacerbate climate change. We need to better understand the interplay of chemical, physical and biological processes that govern soil carbon cycling and stability.The world’s soils contain more carbon than terrestrial vegetation and the atmosphere combined. Although most climate change studies focus on carbon in the skies above us, researchers are also increasingly looking to the ground below. Recognition of the crucial importance of this distinctly heterogeneous carbon reservoir has taken researchers from the tropics to the poles in search of answers. With this issue, we present a collection of articles from Nature Geoscience that highlight the dynamic vulnerability of soil carbon to anthropogenic environmental change.Soil organic carbon is composed of soil microbes, decaying organic matter and degradation products like humus. The long-term stability of this huge carbon pool is dependent on the relative balance between inputs and outputs. Carbon inputs come from the growth of plants and their roots, the transfer of carbon-rich compounds from roots to soil microbes, and the decomposition of leaf litter. Outputs are governed by microbial respiration, which converts organic carbon back to carbon dioxide, soil erosion and leaching.The global distribution and residence time of soil organic carbon is largely controlled by climatic factors, which influence photosynthesis, decomposition and respiration rates. For example, soils in high-latitude regions tend to be carbon-rich as the cold temperatures keep respiration rates down, while higher respiration rates in the warmer tropics result in less stored soil carbon. Climate warming and human disturbance of ecosystems are destabilizing the balance between inputs and outputs and causing soil organic carbon loss, which in turn exacerbates climate change.There is striking evidence of the human influence on soil carbon stocks. As early as about 4,000 years ago, deforestation by the Maya caused reduced carbon retention in soils1. Modern deforestation continues to mobilize old, labile carbon and release it to rivers where it is respired and emitted as carbon dioxide2. Similarly, the drainage of tropical peatlands drives subsidence and soil carbon loss3, while soils in coastal ecosystem are under threat from anthropogenic perturbations such as sea-level rise and eutrophication4. Conservation of these vulnerable ecosystems is needed to minimize soil carbon losses.Global warming and wildfires increasingly threaten permafrost regions in thawing what were perennially frozen, carbon-rich soils. An Article by Keuper et al. demonstrates how microbial processes and decomposition in permafrost soils lead to carbon loss, a feedback exacerbated by the increasing density of plants taking root as soils thaw. Adding to the concern, an Article by Shi et al. reveals that permafrost soils contain the oldest soil organic carbon pool on Earth. This implies that the accumulation and sequestration of carbon in these soils is much slower than predicted by models (see News & Views by Billings and de Souza), while also highlighting the vulnerability of these ecosystems and their carbon stocks to the abrupt changes brought on by climate change.Microbes — capable of both respiring organic carbon and producing stable recalcitrant pools — have a complex relationship with soil carbon. Microbes form a large component of soil organic carbon through their biomass and the organic matter transformations they mediate. Plant–microbe interactions can also influence soil carbon persistence5: microbial formation of soil organic carbon below ground produces mineral-stabilized soil carbon more efficiently than leaf litter inputs above ground6. This dynamic interplay of soil–microbe, carbon–mineral and climatic feedbacks complicates attempts to determine simple relationships between warming and microbial respiration of soil carbon.Researchers are increasingly thinking about how soil systems can be successfully managed to store more carbon and mitigate climate change. In a Perspective, Lehmann et al. describe how the long-term stability of soil carbon is a matter of having the right microbes in the right place at the right time, as not all microbes are capable of decomposing all molecules. They suggest that effective soil management to promote ecosystem health and soil carbon storage needs to be informed by these microscale interactions. Over the longer term the make-up of microbial communities is controlled by weathering processes, which set the nutrient availability in soils7, but how microbial communities respond over shorter timescales remains an open question.As our understanding of soil systems advances, the importance of the carbon underneath our feet to our climate has become increasingly apparent. Leveraging carbon stored in soils could be a powerful climate mitigation strategy, the success of which depends on the careful conservation of vulnerable environments and well-informed process-based management.References1. Douglas, P. M. J. et al. Nat. Geosci. 11, 645–649 (2018).2. Drake, T. W. et al. Nat. Geosci. 12, 541–546 (2019).3. Hoyt, A. M., Chaussard, E., Seppalainen, S. S. & Harvey, C. F. Nat. Geosci. 13, 435–440 (2020).4. Spivak, A. C., Sanderman, J., Bowen, J. L., Canuel, E. A. & Hopkinson, C. S. Nat. Geosci. 12, 685–692 (2019).5. Cotrufo, M. F., Ranalli, M. G., Haddix, M. L., Six, J. & Lugato, E. Nat. Geosci. 12, 989–994 (2019).6. Sokol, N. W. & Bradford, M. A. Nat. Geosci. 12, 46–53 (2019).7. Doetterl, S. et al. Nat. Geosci. 11, 589–593 (2018).Ennis, C., Cable, M.L., Hodyss, R., Maynard-Casely, H.E., 2020. Mixed hydrocarbon and cyanide ice compositions for Titan’s atmospheric aerosols: a ternary-phase co-crystal predicted by density functional theory. ACS Earth and Space Chemistry 4, 1195-1200. benzene/acetylene/hydrogen cyanide co-crystal has been predicted using a periodic density functional theory approach based on the empirical structure of the 1:1 benzene and acetylene co-crystal. This example of a stable ternary-phase system—a three-component co-crystal comprising small neutral molecules—finds relevance as a possible Titan aerosol composition formed by the condensation of abundant volatile photoproducts in the lower stratosphere. Calculated thermochemical data confirm the 2C6H6:C2H2:HCN co-crystal as a viable laboratory target, with free and cohesive energies competitive with those of binary-phase ices. Harmonic vibrational frequencies computed for the periodic system indicate that the co-crystal can be identified using low-frequency far-infrared or Raman spectroscopy, where distinctive intermolecular lattice signatures are predicted to lie. The geometry of the individual components within the unit cell appears optimal to promote ring-expansion chemistry upon ultraviolet or fast particle irradiation of the molecular co-crystal surface. Such co-crystal systems are unexplored in laboratory simulations of astrophysical ices and may have important implications for the solid-state formation of complex organic molecules in Titan’s atmosphere.Evdokimov, I.N., Losev, A.P., 2020. Asphaltene solutions are not adequately described by popular models of solid suspensions. Energy & Fuels 34, 8007-8011. structural parameters of asphaltene nanoparticles are analyzed by employing theoretical models for the properties of solid suspensions in ideal fluids with unvarying composition. This approach ignores the coexistence of colloidally and molecularly dispersed species in the typical asphaltene suspensions used for viscosity and other studies. Molecular dispersed species effectively become parts of the solvent inducing its nonideality, as demonstrated experimentallyEze, S.O., Onwe-Moses, D.F., Okoro, A.U., Aghamelu, O.P., 2020. Organic geochemical characterization of the Cenomanian–Turonian Eze-Aku (southern Benue Trough) and Campanian Nkporo Shales (Anambra Basin), southeastern Nigeria. Arabian Journal of Geosciences 13, 658. study determined and compared, by means of total organic carbon (TOC) content analysis and Rock-Eval pyrolysis, the organic geochemistry and hydrocarbon source rock potentials of the Cenomanian–Turonian Eze-Aku (southern Benue Trough) and Campanian Nkporo Shales (Anambra Basin), southeastern Nigeria. A total of 30 samples, 15 each from both formations, were randomly collected and analyzed. The results indicate that the Eze-Aku Shale has average values of TOC (1.05?wt.%), hydrogen index, Hi, (253?mg HC/g TOC), S2 (3.2?mg HC/g), generative potential, Gp, (3.39?mg·HC/g), and pyrolysis temperature (Tmax) 436?°C that are comparatively higher than those of Nkporo Shale with TOC 0.81?wt.%, Hi 74?mg·HC/g TOC, S2 0.6?mg·HC/g, Gp 0.68?mg·HC/g, and Tmax 432?°C). Also, the average vitrinite reflectance of Eze-Aku Shale (0.67%) is higher than Nkporo Shale which is 0.59%. The organic matter is dominated by the type II and mixed type II/III kerogen for the Eze-Aku Shale and by a type III kerogen for the Nkporo Shale. The implication is that, although both formations have accumulations of marine-sourced organic matter types and would both rate as fair to good hydrocarbon source rocks (TOC?>?0.50?wt.% which is considered the threshold value), the kerogen of Eze-Aku Shale is thermally more mature and is generally oil prone. Conversely, the kerogen of Nkporo Shale is within the immature to early mature stage, and is generally gas prone.Fagliarone, C., Napoli, A., Chiavarini, S., Baqué, M., de Vera, J.-P., Billi, D., 2020. Biomarker preservation and survivability under extreme dryness and Mars-like UV flux of a desert cyanobacterium capable of trehalose and sucrose accumulation. Frontiers in Astronomy and Space Sciences 7, 31. doi: 10.3389/fspas.2020.00031. how long life can persist under extreme dryness and what kind of environmental extremes can be faced by dried microorganisms is relevant to understand Mars habitability and to search for life on planets with transient liquid water availability. Because trehalose and sucrose stabilize dried anhydrobiotes, an in silico survey of the genome of the desert cyanobacterium Chroococcidiopsis sp. CCMEE 029 was performed to identify pathways for trehalose and sucrose biosynthesis. The expression of the identified genes was induced in response to desiccation, and trehalose and sucrose accumulation was detected in dried cells. This adaptation strategy enabled viability and biomarker permanence under extreme dryness and Mars-like UV flux. Chroococcidiopsis survivors were scored in 7-year dried biofilms mixed with phyllosilicatic Mars regolith simulant and exposed to 5.5 × 103 kJ/m2 of a Mars-like UV flux. No survivors occurred after exposure to 5.5 × 105 kJ/m2 although, in dead cells, photosynthetic pigments, and nucleic acids, both DNA and RNA, were still detectable. This suggests that dried biofilms mixed with phyllosilicatic Martian regolith simulant are suitable candidates to identify biosignatures embedded in planetary analog minerals as planned in the future BioSignatures and habitable Niches (BioSigN) space mission to be performed outside the International Space Station.Fagundes, M.B., Vendruscolo, R.G., Wagner, R., 2020. Chapter 21 - Sterols from microalgae, in: Jacob-Lopes, E., Maroneze, M.M., Queiroz, M.I., Zepka, L.Q. (Eds.), Handbook of Microalgae-Based Processes and Products. Academic Press, pp. 573-596. present a diversity of structural compounds that vary according to the metabolism, including zoosterols from animal metabolism and phytosterols from vegetal metabolism. However, microalgae can produce a diversity of sterols, and their biosynthesis can change according to algae metabolism (heterotrophic or autotrophic). Therefore, the culture environment modifications could also influence biosynthesis in sterols. The specific structural features obtained are responsible for distinct bioactivities. In this chapter, we present the diversity of sterols from a wide range of microalgae, from their intermediary molecules to their end pathway products. Therefore, we describe the diversity of pathways involved in their acquirement. Although current research efforts are focused primarily on the structural profiles with their connection in microalgae physiology, studies on the possible biological and culture modifications for their obtainment are still poorly reported. For this reason, we emphasize microalgae as a rich source of sterols and their intermediary, addressing chemical structure, bioactivity, metabolism, and analysis, as well as general aspects related to strategies used to improve sterols’ concentration in microorganisms.Falciglia, P.P., Lumia, L., Giustra, M.G., Gagliano, E., Roccaro, P., Vagliasindi, F.G.A., Di Bella, G., 2020. Remediation of petrol hydrocarbon-contaminated marine sediments by thermal desorption. Chemosphere 260, 127576. this study, a hydrocarbon-contaminated marine sediment was treated applying ex-situ thermal desorption (ESTD) at bench-scale. Temperatures up to 280 °C and heating times (t) in the 5–30 min range were investigated. Results revealed that temperatures in the range 200–280 °C led to Total Petrol Hydrocarbon (TPH)-removal efficiency (RE) from 75 to 85% (t = 10 min). The maximum RE of 89% was obtained at 200 °C for 30 min. However, a shorter remediation time of 5 min (or lower temperatures of 160 and 180 °C with longer times) is needed to reach the TPH standard limit.Data also demonstrated the selectivity of the treatment in TPH fraction removal. The modelling of the TPH removal kinetics and desorption isotherm jointly with activation energy calculation (>30 kJ mol?1) indicated that ESTD process is quite unfavorable for marine sediments. This is due to the fact that ESTD is regulated by chemisorption processes and occurred in two distinct TPH removal phases: evaporation and boiling vaporization. This depends on the strong affinity of the TPH with the fine sediment particles, as well as on the high initial water, salinity, organic matter and sulfides content. However, the comparison between alternative processes has shown that ESTD is the most feasible treatment process for TPH-contaminated marine sediment remediation. Obtained results also add relevant information that can be used as a basis for future scaling-up investigations of ESTD for hydrocarbon-contaminated marine sediments.Fan, C., Li, H., Zhao, S., Qin, Q., Fan, Y., Wu, J., Zhang, J., 2020. Formation stages and evolution patterns of structural fractures in marine shale: Case study of the Lower Silurian Longmaxi Formation in the Changning area of the southern Sichuan Basin, China. Energy & Fuels. the Lower Silurian Longmaxi Formation in the Changning area of the southern Sichuan Basin as an example, the characteristics and formation stages of tectonic fractures are comprehensively studied by regional scale geological analysis and microscopic scale experimental tests. Regional scale geological analysis shows that there are mainly high-angle and vertical structural fractures, which have the characteristics of small opening, large spacing, small fracture density, and high filling degree. The fracture systems can be divided into three stages and six groups, which correspond to the structural compression in the near south–north, northwest, and northeast directions. The microscopic scale experimental test analysis confirmed that the formation of tectonic fractures mainly experienced three stages of tectonic movements, namely, the Middle–Late Yanshanian tectonic movement (136–94 million years ago (Ma)), the Late Yanshanian tectonic movement–Early Himalayan tectonic movement (94–67 Ma), and the Middle–Late Himalayan tectonic movement (67–0 Ma). The corresponding uniform temperatures of the fracture filling inclusions are 118.5–140.2, 91.6–108.5, and 73.2–82.2 °C, respectively. Based on the tectonic analysis and geomechanical principles, an evolutionary model of structural fractures was established. Fractures with early formation and high filling degree and fractures with late formation but large angle between the fracture orientation and current geostress direction are beneficial to shale gas enrichment.Fan, N., Wang, J., Deng, C., Fan, Y., Wang, T., Guo, X., 2020. Quantitative characterization of coal microstructure and visualization seepage of macropores using CT-based 3D reconstruction. Journal of Natural Gas Science and Engineering 81, 103384. of coal microstructure based on 3D reconstruction is of great significance to the development of coalbed methane and the spatial migration of fluids in coal. In this paper, high-resolution X-ray micro-computed tomography (micro-CT) is used to perform CT scanning of the coking coal sample from Shaqu Coal Mine. Then, the quantitative identifying the pores, coal matrix and mineral in coal by using 3D visualization software AVIZO. An equivalent pore network model (PNM) for statistical pore size distribution (PSD) is established based on the “Volume Fraction module” in AVIZO. Finally, the variation of pore pressure, seepage velocity and flow path during the process of methane seepage in pore space are simulated. The results show that the distribution of pores, mineral, and coal matrix are highly heterogeneous, accounting for 8%, 3%, and 89% of the total volume, respectively. PSD statistical analysis showed that most of the pores in the sample space were distributed in the range of 500–1400?nm. With the increase of throat radius and throat length, the number of throat increased first and then decreased. Most of throat equivalent radius is less than 700?nm. The equivalent length of the throat is mainly distributed in the range of 1500–4500?nm. Under the same pressure gradient, the distribution of the pore pressure, seepage velocity and flow path in the three directions are different, which shows the high heterogeneity of the pore structure. During the methane seepage process, the pore pressure gradually decreases, and the smaller the pore radius, the more obvious the pressure change. As the pressure gradient increases, the seepage velocity of methane gradually increases, and the curve presents the obvious nonlinear relationship. In the pore structure, the sudden decrease of the pore radius in some areas causes the seepage velocity increases sharply.Fayolle, E.C., Noell, A.C., Johnson, P.V., Hodyss, R., Ponce, A., 2020. Viability of Bacillus subtilis spores exposed to ultraviolet light at ocean world surface temperatures. Astrobiology 20, 889-896. work investigated microorganism survival under temperature and ultraviolet (UV) radiation conditions found at the surface of ice-covered ocean worlds. These studies were motivated by a desire to understand the ability of resilient forms of life to survive under such conditions as a proxy for potential endogenic life and to inform planetary protection protocols for future missions.To accomplish this, we irradiated Bacillus subtilis spores with solar-like UV photons at temperatures ranging from room temperature down to 11 K and reported survival fractions with respect to fluence. We observed an increase in survival at low temperatures and found that the inactivation rate follows an Arrhenius-type behavior above 60 K. For solar-photon fluxes and surface temperatures at Europa and Enceladus, we found that Bacillus subtilis spores would be inactivated in less than an hour when in direct sunlight. Feng, J., Yang, F., Wu, J., Chen, Q., Zhang, Q., Cheng, X., 2020. Contrasting soil C and N dynamics inferred from δ13C and δ15N values along a climatic gradient in southern China. Plant and Soil 452, 217-231.: Secondary grasslands reestablished after deforestation in subtropical and tropical regions greatly alter terrestrial carbon (C) and nitrogen (N) dynamics and their associated ecosystem functions. However, reliable evaluations of C and N dynamics in secondary grasslands across regional climatic gradient remain challenging.Methods: We investigated natural 13C and 15N abundance in plants and soil as well as their associations with environmental factors (including climatic, plant and edaphic variables) from 20 sites across a 600 km climatic gradient in secondary grasslands of southern China.Results: The δ13C values in plants and soil declined with increasing mean annual precipitation (MAP) but increased as the mean annual temperature (MAT) increased. These changes were mostly attributed to the shift in plant functional group between C4 and C3. In contrast, increasing MAP and decreasing MAT had positive effects on soil δ15N values, which were mainly related to changes in edaphic factors, including soil pH, soil C and N content and soil C:N ratios.Conclusions: Our findings indicate inverse patterns and different controls on soil δ13C and δ15N values along the climatic gradient, providing novel insights into the underlying mechanisms of ecosystem C and N dynamics in response to climate and vegetation change in secondary grasslands.Feng, Z., Hao, F., Zhou, S., Wu, W., Tian, J., Xie, C., Cai, Y., 2020. Pore characteristics and methane adsorption capacity of different lithofacies of the Wufeng Formation–Longmaxi Formation shales, southern Sichuan Basin. Energy & Fuels 34, 8046-8062. significantly different geological processes experienced by the shales in the southern Sichuan Basin provide a means for comparing their pore characteristics and their supercritical methane adsorption capacities. In this study, we analyzed the Wufeng Formation (O3w)–Longmaxi Formation (S1l) shales in the southern Sichuan Basin using multiple analytical methods, including mineralogy, field emission scanning electron microscopy (FE-SEM), mercury intrusion capillary pressure (MICP), low-pressure gas adsorption (LPGA), and high-pressure methane adsorption. Four types of shale lithofacies were identified including clay-rich siliceous shale (S-3), argillaceous/siliceous mixed shale (M-2), silica-rich argillaceous shale (CM-1), and mixed argillaceous shale (CM-2). With increasing burial depth, the pore system gradually shifted from organic matter (OM) pores to intergranular (interP) pores between the OM clumps and the brittle minerals. The results of the MICP and LPGA were not significantly affected by burial depth, but were closely related to the total organic carbon (TOC) content and lithofacies. The surface areas and total pore volumes (Vp’s) varied from 5.44 to 11.73 m2/g with an average of 9.89 m2/g and from 0.88 to 2.04 cm3/100 g, respectively. Patterns in the Vp and surface area values of the S-3 and M-2 samples exhibited four-modal features, while the CM samples were bimodal. The excess adsorption capacity reached its maximum value when the pressure was about 9–11 MPa, and then it decreased as the pressure increased. The mesopores provided the main Vp (average 43.1%), and the micropores provided the main surface area (average 74.38%). The adsorption positions of the gas molecules can be provided by micropores and mesopores, and even by microcracks and macropores, and as the TOC content of the shale increases, the contribution of the micropores to adsorption becomes more significant.Ferry, J.G., 2020. Methanosarcina acetivorans: A model for mechanistic understanding of aceticlastic and reverse methanogenesis. Frontiers in Microbiology 11, 1806. doi: 10.3389/fmicb.2020.01806. methanogens are responsible for approximately two-thirds of the one billion metric tons of methane produced annually in Earth’s anaerobic environments. Methanosarcina acetivorans has emerged as a model organism for the mechanistic understanding of aceticlastic methanogenesis and reverse methanogenesis applicable to understanding the methane and carbon cycles in nature. It has the largest genome in the Archaea, supporting a metabolic complexity that enables a remarkable ability for adapting to environmental opportunities and challenges. Biochemical investigations have revealed an aceticlastic pathway capable of fermentative and respiratory energy conservation that explains how Ms. acetivorans is able to grow and compete in the environment. The mechanism of respiratory energy conservation also plays a role in overcoming endothermic reactions that are key to reversing methanogenesis.Fischer, S., Fralick, P., 2019. Biological mats in siliciclastic sediments of the Paleoproterozoic Gunflint Formation, northwestern Ontario, Canada. Canadian Journal of Earth Sciences 57, 947-953. Gunflint Formation of northwestern Ontario, Canada, contains an extensive array of stromatolite morphologies and associated fossilized bacteria. It, and correlative units in the United States, provided some of the most persuasive early interpretations of stromatolites and evidence of Precambrian bacterial life. This study examined the siliciclastic rocks in the Gunflint Formation and discovered a multitude of features formed by the development of cohesive biogenic mats on bedding surfaces. In former shallow subtidal depositional settings, evidence of mat erosion was most common, with the presence of various types of wrinkle structures. Microscopically carbonaceous layers and rip-up fragments representing mats and their eroded remnants are well preserved. This emphasizes the abundance of bacterial life in the shallow nearshore of the Gunflint Formation about 1.88 billion years ago and further indicates an increased flux of reductants was necessary during this time period to establish low oxygen levels in the ocean.Fogwill, C.J., Turney, C.S.M., Menviel, L., Baker, A., Weber, M.E., Ellis, B., Thomas, Z.A., Golledge, N.R., Etheridge, D., Rubino, M., Thornton, D.P., van Ommen, T.D., Moy, A.D., Curran, M.A.J., Davies, S., Bird, M.I., Munksgaard, N.C., Rootes, C.M., Millman, H., Vohra, J., Rivera, A., Mackintosh, A., Pike, J., Hall, I.R., Bagshaw, E.A., Rainsley, E., Bronk-Ramsey, C., Montenari, M., Cage, A.G., Harris, M.R.P., Jones, R., Power, A., Love, J., Young, J., Weyrich, L.S., Cooper, A., 2020. Southern Ocean carbon sink enhanced by sea-ice feedbacks at the Antarctic Cold Reversal. Nature Geoscience 13, 489-497. Southern Ocean occupies 14% of the Earth’s surface and plays a fundamental role in the global carbon cycle and climate. It provides a direct connection to the deep ocean carbon reservoir through biogeochemical processes that include surface primary productivity, remineralization at depth and the upwelling of carbon-rich water masses. However, the role of these different processes in modulating past and future air–sea carbon flux remains poorly understood. A key period in this regard is the Antarctic Cold Reversal (ACR, 14.6–12.7?kyr bp), when mid- to high-latitude Southern Hemisphere cooling coincided with a sustained plateau in the global deglacial increase in atmospheric CO2. Here we reconstruct high-latitude Southern Ocean surface productivity from marine-derived aerosols captured in a highly resolved horizontal ice core. Our multiproxy reconstruction reveals a sustained signal of enhanced marine productivity across the ACR. Transient climate modelling indicates this period coincided with maximum seasonal variability in sea-ice extent, implying that sea-ice biological feedbacks enhanced CO2 sequestration and created a substantial regional marine carbon sink, which contributed to the plateau in CO2 during the ACR. Our results highlight the role Antarctic sea ice plays in controlling global CO2, and demonstrate the need to incorporate such feedbacks into climate–carbon models.Fraisier-Vannier, O., Chervin, J., Cabanac, G., Puech, V., Fournier, S., Durand, V., Amiel, A., André, O., Benamar, O.A., Dumas, B., Tsugawa, H., Marti, G., 2020. MS-CleanR: A feature-filtering workflow for untargeted LC–MS based metabolomics. Analytical Chemistry 92, 9971-9981. metabolomics using liquid chromatography–mass spectrometry (LC–MS) is currently the gold-standard technique to determine the full chemical diversity in biological samples. However, this approach still has many limitations; notably, the difficulty of accurately estimating the number of unique metabolites profiled among the thousands of MS ion signals arising from chromatograms. Here, we describe a new workflow, MS-CleanR, based on the MS-DIAL/MS-FINDER suite, which tackles feature degeneracy and improves annotation rates. We show that implementation of MS-CleanR reduces the number of signals by nearly 80% while retaining 95% of unique metabolite features. Moreover, the annotation results from MS-FINDER can be ranked according to the database chosen by the user, which enhance identification accuracy. Application of MS-CleanR to the analysis of Arabidopsis thaliana grown in three different conditions fostered class separation resulting from multivariate data analysis and led to annotation of 75% of the final features. The full workflow was applied to metabolomic profiles from three strains of the leguminous plant Medicago truncatula that have different susceptibilities to the oomycete pathogen Aphanomyces euteiches. A group of glycosylated triterpenoids overrepresented in resistant lines were identified as candidate compounds conferring pathogen resistance. MS-CleanR is implemented through a Shiny interface for intuitive use by end-users (available at ).Frei, R., Lehmann, B., Xu, L., Frederiksen, J.A., 2020. Surface water oxygenation and bioproductivity – A link provided by combined chromium and cadmium isotopes in Early Cambrian metalliferous black shales (Nanhua Basin, South China). Chemical Geology 552, 119785. intrinsic link between atmospheric oxygenation, surface seawater redox and bioproductivity in the upper water column of oceans offers to combine cadmium with chromium isotopes in marine archives to deduce information on past controls of biological metal and nutrient cycling. We here use a novel approach in combining chromium and cadmium isotope signatures in metalliferous and organic matter (OM) rich shales from the Early Cambrian Niutitang formation (south China) to reconstruct the surface water redox and cycling of bioessential metals, in a period directly following the Cambrian animal evolution. The inventory of authigenic Cd in the black shales is controlled by their sulfide abundance, whereas authigenic Cr is dominantly controlled by iron(oxy-)hydroxides and OM. Cadmium isotopes measured on bulk sediments and 3 N HNO3 leachates exhibit ε114Cd values from ?1.5 to +4.5, with Mo–Ni rich sulfidic shales revealing elevated values > + 2.5. Chromium isotopes define δ53Cr values from +0.4 to +1.7‰, with V-rich non-sulfidic shales yielding more positively fractionated signatures than Mo–Ni rich sulfidic shales. The negative δ53Cr-ε114Cd correlation trend recorded in the black shales suggests a high-ε114Cd sulfide endmember of authigenic Cd preserved in anoxic bottom conditions. The other endmember is constituted by OM with the isotopically heavy Cr and light Cd signals reflecting efficient phytoplankton uptake in the photic zone. The endmembers constrain the Cd and Cr isotope signatures of surface waters in the Early Cambrian Nanhua Basin to ε114Cd of ~ +7 to +17, and to δ53Cr of ~ + 0.7 to +1.9‰. These values are compatible with those of modern ocean surface waters and attest to a Cambrian surface ocean water sustaining elevated primary bioproductivity in the aftermath of late Ediacaran snowball Earth glaciations. Our study emphasizes the potential of the Cr–Cd double tracer in studies aimed at the reconstruction of paleoproductivity and (bio)geochemical metal cycling in marine paleo-basins.Fu, Q.-L., Fujii, M., Riedel, T., 2020. Development and comparison of formula assignment algorithms for ultrahigh-resolution mass spectra of natural organic matter. Analytica Chimica Acta 1125, 247-257. number of application of ultrahigh-resolution mass spectrometry (UHR-MS) to natural organic matter (NOM) characterization requires an efficient and accurate formula assignment from a number of mass data. Herein, we newly developed two automated batch codes (namely TRFu and FuJHA) and assessed their formula assignment accuracy together with frequently used open access algorithms (i.e., Formularity and WHOI). Overall assignment accuracy for 8,719 NOM-like emerging chemicals with known molecular formulae (mass range from 68 Da to 1,000 Da) was highest (94%) for TRFu. Further, TRFu showed up to 99.1% formula assignment ratio for a total 76,880 UHR-MS peaks from 35 types of NOM (e.g., aquatic, soil/sediment, biochar). Therefore, as a reliable and practically feasible tool, the automated batch TRFu (freely available at ChemRxiv, ) can precisely characterize UHR-MS spectra of various NOM and could be extended to non-target screening of NOM-like emerging chemicals in natural and engineered environments.Fujito, Y., Hayakawa, Y., Bamba, T., 2020. Development of a novel comprehensive analytical method for volatile compounds using supercritical fluid chromatography/mass spectrometry with a highly cross-linked styrene divinylbenzene polymer-based column. Journal of Chromatography A 1626, 461363. techniques to determine volatile compounds such as flavor, aroma, and fragrances are in high demand due to their wide range of applications in industry, the chemical properties of them are very diverse. Supercritical fluid chromatography (SFC) is capable of high speed, high peak capacity separation and has a high separation coverage. It is also an advantageous for preparative purifications due to its unique mobile phase conditions. However, there is no column commercially available for SFC that is suitable to comprehensively separate volatile compounds. SFC is limited to the use of silica-based columns due to weak retentions and polymer-based column issues such as pressure, swelling and shrinkage tolerances. This study demonstrated comprehensive analytical method for volatile in SFC using a highly cross-linked styrene divinylbenzene (SDVB) polymer-based column, newly developed for SFC. In this study, 23 typical volatile compounds with a wide variety of chemical properties were selected as model compounds. The newly developed SDVB column showed, compared to conventional silica-based columns (k > 0.3), an excellent overall and substantial improved retentions (k > 1.6) under SFC mobile phase conditions. It was also able to retain esters (hydroxy acetate, pentyl butylate, methyl salicylate) and non-polar terpenes (limonene, pinene) that did not show sufficient retention in any other commercially available silica-based columns. Aldehydes reacting on NH2 column due to Schiff base formation were also successfully eluted. It was confirmed that SDVB column provided comprehensive separation and wide coverage for volatile compounds.Gachumi, G., Purves, R.W., Hopf, C., El-Aneed, A., 2020. Fast quantification without conventional chromatography, the growing power of mass spectrometry. Analytical Chemistry 92, 8628-8637. spectrometry (MS) in hyphenated techniques is widely accepted as the gold standard quantitative tool in life sciences. However, MS possesses intrinsic analytical capabilities that allow it to be a stand-alone quantitative technique, particularly with current technological advancements. MS has a great potential for simplifying quantitative analysis without the need for tedious chromatographic separation. Its selectivity relies on multistage MS analysis (MSn), including tandem mass spectrometry (MS/MS), as well as the ever-growing advancements of high-resolution MS instruments. This perspective describes various analytical platforms that utilize MS as a stand-alone quantitative technique, namely, flow injection analysis (FIA), matrix assisted laser desorption ionization (MALDI), including MALDI-MS imaging and ion mobility, particularly high-field asymmetric waveform ion mobility spectrometry (FAIMS). When MS alone is not capable of providing reliable quantitative data, instead of conventional liquid chromatography (LC)-MS, the use of a guard column (i.e., fast chromatography) may be sufficient for quantification. Although the omission of chromatographic separation simplifies the analytical process, extra procedures may be needed during sample preparation and clean-up to address the issue of matrix effects. The discussion of this manuscript focuses on key parameters underlying the uniqueness of each technique for its application in quantitative analysis without the need for a chromatographic separation. In addition, the potential for each analytical strategy and its challenges are discussed as well as improvements needed to render them as mainstream quantitative analytical tools. Overcoming the hurdles for fully validating a quantitative method will allow MS alone to eventually become an indispensable quantitative tool for clinical and toxicological studies.Gagné, K.R., Ewers, S.C., Murphy, C.J., Daanen, R., Walter Anthony, K., Guerard, J.J., 2020. Composition and photo-reactivity of organic matter from permafrost soils and surface waters in interior Alaska. Environmental Science: Processes & Impacts 22, 1525-1539. permafrost soils are especially susceptible to abrupt thaw due to their exceptional thickness and high ice content. Compared to other mineral soils, yedoma has a high organic carbon content, which has shown to be particularly biolabile. The organic carbon in these deposits needs to be characterised to provide an identification toolkit for detecting and monitoring the thaw, mobilisation and mineralisation of yedoma permafrost. This study characterised organic carbon isolates from thermokarst lakes (either receiving inputs from thaw of original yedoma or refrozen-thermokarst deposits, or lacking recent thaw) during winter and summer seasons within the Goldstream Creek watershed, a discontinuous permafrost watershed in interior Alaska, to identify the extent to which thermokarst-lake environments are impacted by degradation of yedoma permafrost. Waters from lakes of varied age and thermokarst activity, as well as active layer and undisturbed yedoma permafrost soils were isolated and characterised by functional group abundance (multiCP-MAS 13C and SPR-W5-WATERGATE 1H NMR), absorbance and fluorescence, and photobleaching ability. DOM isolated from winter and summer seasons revealed differing composition and photoreactivity, suggesting varied active layer and permafrost influence under differing ground water flow regimes. Water extractable organic matter isolates from permafrost leachates revealed variation in terms of photoreactivity and photolability, with the youngest sampled permafrost isolate being the most photoreactive and photolabile. As temperatures increase, release of permafrost organic matter is inevitable. Obtaining a holistic understanding of DOM composition and photoreactivity will allow for a better prediction of permafrost thaw impacts in the coming decades.Gai, H., Li, T., Wang, X., Tian, H., Xiao, X., Zhou, Q., 2020. Methane adsorption characteristics of overmature Lower Cambrian shales of deepwater shelf facies in Southwest China. Marine and Petroleum Geology 120, 104565. Lower Cambrian shales of deepwater shelf facies comprise an important part of the marine black shales in southern China. In this study, twenty-four Lower Cambrian shale samples from southwest China were subjected to analysis of geochemistry, pore structure and methane adsorption capacity. The samples have total organic carbon (TOC) contents ranging from 0.25% to 11.3% and equivalent vitrinite reflectance (EqVRo) values in the range of 2.51–4.23%. Specific surface areas determined from N2 adsorption at 77.4 K and specific micropore volumes from CO2 adsorption at 273.15 K are in the range of 3.0–38.6 m2/g rock and 2.5–11.4 cm3/kg rock, respectively, and both of them have positive relationships with TOC values. The Langmuir volumes of these samples at 60 °C range from 0.47 cm3/g rock to 5.96 cm3/g rock and are positively correlated with TOC values, which on the one hand confirms the TOC control on methane adsorption capacity and on the other hand also suggests a weak control of thermal maturity on methane adsorption capacity at overmature stages. Although both specific surface area and specific micropore volume are positively correlated with methane adsorption capacity, the latter seems to have a stronger effect and the specific micropore volume determined from subcritical CO2 adsorption may be considered as a proxy for the volume of adsorbed methane in dry shales. For the extrapolation of measured methane excess adsorption isotherms to geological conditions, the use of a constant or varying Langmuir volume makes no significant difference with respect to the methane storage capacity of shales when the density of the adsorbed methane is allowed to change with temperature. However, the absolute methane adsorption quantity at subsurface is obviously dependent on the use of a constant or varying Langmuir volume, which subsequently affects the estimation of the relative percentages of adsorbed and free methane.Galletti, Y., Becagli, S., di Sarra, A., Gonnelli, M., Pulido-Villena, E., Sferlazzo, D.M., Traversi, R., Vestri, S., Santinelli, C., 2020. Atmospheric deposition of organic matter at a remote site in the central Mediterranean Sea: implications for the marine ecosystem. Biogeosciences 17, 3669-3684. fluxes of dissolved organic matter (DOM) were studied for the first time on the island of Lampedusa, a remote site in the central Mediterranean Sea (Med Sea), between 19 March 2015 and 1 April 2017. The main goals of this study were to quantify total atmospheric deposition of DOM in this area and to evaluate the impact of Saharan dust deposition on DOM dynamics in the surface waters of the Mediterranean Sea. Our data show high variability in DOM deposition rates without a clear seasonality and a dissolved organic carbon (DOC) input from the atmosphere of 120.7?mmol?DOC?m?2?yr?1. Over the entire time series, the average dissolved organic phosphorus (DOP) and dissolved organic nitrogen (DON) contributions to the total dissolved pools were 40?% and 26?%, respectively. The data on atmospheric elemental ratios also show that each deposition event is characterized by a specific elemental ratio, suggesting a high variability in DOM composition and the presence of multiple sources. This study indicates that the organic substances transported by Saharan dust on Lampedusa mainly come from a natural sea spray and that Saharan dust can be an important carrier of organic substances even though the load of DOC associated with dust is highly variable. Our estimates suggest that atmospheric input has a larger impact on the Med Sea than on the global ocean. Further, DOC fluxes from the atmosphere to the Med Sea can be up to 6 times larger than total river input. Longer time series combined with modeling would greatly improve our understanding of the response of DOM dynamics in the Med Sea to the change in aerosol deposition pattern due to the effect of climate change.Galvez, M.E., Fischer, W.W., Jaccard, S.L., Eglinton, T.I., 2020. Materials and pathways of the organic carbon cycle through time. Nature Geoscience 13, 535-546. cycle of organic carbon through the atmosphere, oceans, continents and mantle reservoirs is a hallmark of Earth. Over geological time, chemical exchanges between those reservoirs have produced a diversity of reduced carbon materials that differ in their molecular structures and reactivity. This reactive complexity challenges the canonical dichotomy between the surface and deep, short-term and long-term organic carbon cycle. Old and refractory carbon materials are not confined to the lithosphere but are ubiquitous in the surface environment, and the lithosphere hosts various forms of reduced carbon that can be very reactive. The biological and geological pathways that drive the organic carbon cycle have changed through time; from a synthesis of these changes, it emerges that although a biosphere is required to produce organic carbon, mortality is required to ensure its export to the lithosphere, and graphitization is essential for its long-term stabilization in the solid Earth. Among the by-products of the organic carbon cycle are the accumulation of a massive lithospheric reservoir of organic carbon, the accumulation of dioxygen in the atmosphere and the rise of a terrestrial biosphere. Besides driving surface weathering reactions, free dioxygen has allowed the evolution of new metabolic pathways to produce and respire organic carbon. From the evolution of photosynthesis until the expansion of biomineralization in the Phanerozoic, inorganic controls on the organic carbon cycle have diversified, tightening the connection between the biosphere and geosphere.Ganeeva, Y.M., Yusupova, T.N., Barskaya, E.E., Okhotnikova, E.S., Romanov, G.V., 2020. Comparative analysis of the composition of carbon-rich rocks from Domanik deposits and the oil–water contact zone exemplified by Tatarstan’s Bavly oilfield. Petroleum Chemistry 60, 659-667. of carbon-rich rocks from domanik deposits and the oil–water contact zone of the Bavly field of the Republic of Tatarstan (Russia), as well as extracts from them, have been studied by thermal analysis, IR and EPR spectroscopy, and gas–liquid chromatography. Significant differences have been revealed in the chemical composition and physicochemical properties of both soluble and insoluble organic matter from various areas of the Bavly field. Compared with bitumens from the oil–water contact zone, bitumoids from domanik deposits are heavier; they are enriched in oxidized structures and contain elevated levels of isoprenoid hydrocarbons and light normal alkanes. Bitumoid asphaltenes are enriched in sulfur and nitrogen, depleted in oxygen, and characterized by an increased concentration of paramagnetic centers. These differences have to be taken into account when testing technologies for the development of domanik deposits.Ganino, C., Libourel, G., 2020. Fumarolic-like activity on carbonaceous chondrite parent body. Science Advances 6, eabb1166. planetology studies are key for understanding the main processes driving planetary formation and evolution. None have been yet applied to pristine asteroids formed in the solar protoplanetary disk, mainly because of their comminution during their 4.5-billion-year collisional lifetime. From remarkable textural, mineralogical, chemical, and thermodynamic similarities, we show that the high-temperature Kudryavy volcano fumarolic environment from Kurile Islands is a likely proxy of the Fe-alkali-halogen metasomatism on the CV and CO carbonaceous chondrite parent bodies. Ca-Fe–rich and Na-Al-Cl–rich secondary silicates in CV and CO chondrites are, thus, inferred to be fumarolic-like incrustations that precipitate from hot and reduced hydrothermal vapors after interactions with the wallrocks during buoyancy-driven Darcy flow percolation. These vapors may originate from the progressive heating and devolatilization of a chondritic protolith on their parent body or are remnant of the cooling of residual local nebular gases at the time of their primary planetesimal accretion.Garayburu-Caruso, V.A., Stegen, J.C., Song, H.-S., Renteria, L., Wells, J., Garcia, W., Resch, C.T., Goldman, A.E., Chu, R.K., Toyoda, J., Graham, E.B., 2020. Carbon limitation leads to thermodynamic regulation of aerobic metabolism. Environmental Science & Technology Letters 7, 517–524. matter (OM) metabolism in freshwater ecosystems is a critical source of uncertainty in global biogeochemical cycles, yet the processes regulating aerobic respiration in aquatic environments remain poorly understood. Aerobic respiration is typically predicted through kinetic controls such as organic carbon and oxygen concentrations, while assuming thermodynamic regulation has no influence. The role of OM thermodynamics has been mainly explored under anaerobic conditions; however, recent observations have suggested that thermodynamic properties of OM may influence aerobic respiration rates. Here, we explicitly test OM thermodynamics as a key regulator of aerobic respiration. We pair controlled microcosm experiments with ultrahigh-resolution OM characterization to show that aerobic respiration increases with OM thermodynamic favorability under carbon limitation. We also demonstrate a shift in the regulation of aerobic respiration from OM thermodynamics to nitrogen content when carbon is in excess, highlighting a central role for OM thermodynamics particularly in carbon-limited ecosystems. This illuminates a structural gap in aquatic biogeochemical models by demonstrating that both kinetic and thermodynamic constraints can modulate aerobic respiration. Our work therefore proposes a new conceptual model in which thermodynamic and nutrient limitations dually control aerobic respiration.Garcia Alc?ntara, J.M., Distante, F., Storti, G., Moscatelli, D., Morbidelli, M., Sponchioni, M., 2020. Current trends in the production of biodegradable bioplastics: The case of polyhydroxyalkanoates. Biotechnology Advances 42, 107582. global pollution caused by plastics and microplastics is stimulating intense research towards more environmentally friendly materials, preserving the remarkable application characteristics of the currently available polymers. Among these, polyhydroxyalkanoates (PHAs) have been hailed as the solution to replace conventional, oil-based plastics. Given their biodegradable nature and mechanical properties, their use can be envisioned in a wide range of applications reducing the environmental footprint. Several types of processes have been proposed for their production, which can be grouped in three main classes: (i) microbiological, (ii) enzymatic and (iii) chemical processes. Given the significant amount of literature available on this topic, this review aims to critically analyse what has been proposed so far in each of these classes, with specific reference to their potential to provide bioplastics that can actually replace the currently available materials. A comparison is made, based on the following aspects: achievable molecular structures (such as molecular weight and composition distributions), raw-material and production costs and availability of large-scale production technologies. Finally, some considerations and ideas on what should be further investigated and implemented to realize the economically sustainable production of PHA are brought forward.Geelhoed, J.S., van de Velde, S.J., Meysman, F.J.R., 2020. Quantification of cable bacteria in marine sediments via qPCR. Frontiers in Microbiology 11, 1506. doi: 10.3389/fmicb.2020.01506. bacteria (Deltaproteobacteria, Desulfobulbaceae) are long filamentous sulfur-oxidizing bacteria that generate long-distance electric currents running through the bacterial filaments. This way, they couple the oxidation of sulfide in deeper sediment layers to the reduction of oxygen or nitrate near the sediment-water interface. Cable bacteria are found in a wide range of aquatic sediments, but an accurate procedure to assess their abundance is lacking. We developed a qPCR approach that quantifies cable bacteria in relation to other bacteria within the family Desulfobulbaceae. Primer sets targeting cable bacteria, Desulfobulbaceae and the total bacterial community were applied in qPCR with DNA extracted from marine sediment incubations. Amplicon sequencing of the 16S rRNA gene V4 region confirmed that cable bacteria were accurately enumerated by qPCR, and suggested novel diversity of cable bacteria. The conjoint quantification of current densities and cell densities revealed that individual filaments carry a mean current of ～110 pA and have a cell specific oxygen consumption rate of 69 fmol O2 cell–1 day–1. Overall, the qPCR method enables a better quantitative assessment of cable bacteria abundance, providing new metabolic insights at filament and cell level, and improving our understanding of the microbial ecology of electrogenic sediments.Ghosh, S., Ojha, A., Varma, A.K., 2020. Spectral manifestations of coal metamorphism: Insights from coal microstructural framework. International Journal of Coal Geology 228, 103549. present study investigates the microstructural framework of coals from the Raniganj and the Jharia Basins as well as from the Himalayan fold-thrust belts of Sikkim, India, by vitrinite reflectance, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The mean random vitrinite reflectance data may imply that the coal samples from the Raniganj and the Jharia Basins range from the bituminous D to B, and would have experienced the burial heating corresponding to ~92 °C to 143 °C unlike the anthracite A samples that might have undergone the hydrothermal metamorphism at ~333 °C to 367 °C. The Raman spectra exhibit preferential removal of sp3 hybridized moieties from the anthracite samples at anchizonal metamorphic stage due to thermo-stress degradation effect induced by the Himalayan orogeny. Further, this study records the reduction of net dipole moment change due to the expulsion of functional groups from the aromatic rings making them infrared inactive. Additionally, the C1s spectra reveal the thinning of C-C peaks and the lowering of the C-O peak intensity with an increase in coal rank. This study, hence, documents the microstructural transformations in coal that can be used for structural maneuvering to control the liquefaction, gasification, pyrolysis, combustion as well as synthetic graphitization behavior.Ghosh, S., Sanyal, P., Roy, S., Bhushan, R., Sati, S.P., Philippe, A., Juyal, N., 2020. Early Holocene Indian summer monsoon and its impact on vegetation in the Central Himalaya: Insight from δD and δ13C values of leaf wax lipid. The Holocene 30, 1063-1074. in rainfall during the early Holocene has been reported from different regions of Indian subcontinent, although the magnitude shows spatial variability with lower change in higher rainfall regions and vice versa. While the early-Holocene rainfall records are available from lowland areas of the Indian sub-continent, the record is poorly documented from the high-altitude Central Himalayan region where orography plays an important role in the spatial variability in the rainfall pattern. For the first time, δDC29, δ13CC29 values of alkane and δ13C values of organic matter from a relict lake of Benital area in the Central Himalaya have been used to reconstruct monsoonal rainfall and contemporary vegetation for last 10.5 ka with an emphasis on the early Holocene. The δDC29 values suggest that the early Holocene was characterized by a wet phase at ca. 9 ka with 25% higher rainfall compared to present while the middle-late-Holocene was relatively arid. The estimated increase in monsoonal rainfall for the early Holocene is the highest compared to the previous report from elsewhere. The magnitude of early-Holocene rainfall estimated in this study suggests that in addition to erosion of the bed-rocks at the head-water region, increased stream power reworked the older floodplain and resulted in 2.3 times higher sediment discharged into the Ganges-Brahmaputra (GB) delta compared to the present discharge. The δ13CC29 values of the lake sediments suggest a transition from woody to non-woody plant assemblages occurred at 7 ka. The poor correlation between δDC29 and δ13CC29 values suggests at higher rainfall, the δ13CC29 values of catchment vegetation were less responsive.Gibbons, A., 2020. How an ancient microbial arms race remodeled human cells. Science 369, 491-492. a recent symposium on the evolution of infectious diseases, University of California, San Diego (UCSD), pathologist Nissi Varki noted that humans suffer from a long list of deadly diseases—including typhoid fever, cholera, mumps, whooping cough, and gonorrhea—that don't afflict apes and most other mammals. All of those pathogens follow the same well-trodden pathway to break into our cells: They manipulate sugar molecules called sialic acids. Hundreds of millions of these sugars stud the outer surface of every cell in the human body—and the sialic acids in humans are different from those in apes.Varki and an international team of researchers have now traced how evolution may have scrambled to construct new defenses after that molecular vulnerability emerged in our distant ancestors. By analyzing modern human genomes and ancient DNA from our extinct cousins, the Neanderthals and Denisovans, the researchers detected a burst of evolution in our immune cells that occurred in an ancestor of all three types of human by at least 600,000 years ago.As the researchers report in the current issue of Genome Biology and Evolution, these genetic changes may have sharpened the body's defenses against the pathogens that evolved to exploit sialic acids—but created new vulnerabilities. In an added irony, they note, humans' distinctive sialic acids were themselves once a defense against disease. The evolutionary saga is a vivid illustration of the competition between humans and microbes, says microbiologist Christine Szymanski of the University of Georgia, Athens, who is not a co-author. “This gives us a human perspective on how we have to keep changing to keep pace.”The arena for this evolutionary arms race is the glycocalyx, a sugar coating that protects the outer membrane of all cells. It consists of a forest of molecules that sprout from the cell membrane. The sialic acids are at the tip of the tallest branches, sugar chains called glycans, which are rooted to fats and proteins deeper in the membrane.Given their prominence and sheer number, sialic acids are usually the first molecules that invading pathogens encounter. Human cells are coated with one type of sialic acid, N-acetylneuraminic acid (Neu5Ac). But apes and most other mammals also carry a different one, N-glycolylneuraminic acid (Neu5Gc).More than 2 million years ago, according to multiple molecular clock methods that estimate when mutations arose, a mutation in a gene on chromosome six made it impossible for human ancestors to make Neu5Gc anymore; instead, they made more of another sialic acid, Neu5Ac (Science, 4 September 1998, p. 1432). “We now know we had an ancient complete makeover of the surface of the human cells,” says evolutionary biologist Pascal Gagneux of UCSD, a co-author of the new paper. Birds, some bats, ferrets, and New World monkeys all separately made the same evolutionary change.The change likely evolved as a defense against malaria, says UCSD physician-scientist Ajit Varki, senior author of the paper and Nissi Varki's spouse. Malarial parasites that infect chimpanzees were no longer able to bind with the altered sialic acids on our red blood cells (Science, 24 September 2010, p. 1586).But in the next million years or so, that mutation became a liability, as Neu5Ac became a portal for a flurry of other pathogens. At the infectious disease symposium organized by UCSD's Center for Academic Research and Training in Anthropogeny, researchers described how multiple diseases evolved to use Neu5Ac to enter cells or to evade immune cells.Coronaviruses appear to be no exception. “Most coronaviruses infect cells in two steps—first by recognizing abundant sialic acids as binding sites to gain a foothold, and then seeking out the higher affinity protein receptors like ACE2,” Ajit Varki says. “Think of it like an initial handshake or introduction that is required before one can ask for a date.” Two preprints suggest the novel coronavirus, SARS-CoV-2, also docks with sialic acids before binding with the ACE2 receptor to pierce human cells.In past studies, Ajit Varki and Gagneux suggested the makeover of the cell and the loss of Neu5Gc may have even contributed to the origin of a new species in our genus Homo. If a woman with only Neu5Ac sialic acids mated with a man who still expressed Neu5Gc, her immune system may have rejected that man's sperm or the fetus that developed from it. This fertility barrier might have helped divide Homo populations into different species more than 2 million years ago, the researchers speculated.But the sialic acid change also sparked a new arms race between pathogens and our ancestors. In the new study, the researchers scanned DNA for immune genes in six Neanderthals, two Denisovans, and 1000 humans, and looked at dozens of chimps, bonobos, gorillas, and orangutans as well. They found evolutionary changes that “markedly altered” one class of proteins—sialic acid-binding immunoglobulin-type lectins, or Siglecs—that usually sit on the surface of human immune cells and recognize sialic acids.Siglecs are molecular sentries: They probe sialic acids to see whether they are familiar parts of our own bodies or foreign invaders. If Siglecs spot sialic acids that are damaged or missing, they signal immune cells to activate, rousing an inflammatory army to attack potential invaders or clean up damaged cells. If sialic acids instead appear to be normal parts of our own cells, other, inhibitory Siglecs throttle back immune defenses so as not to attack our own tissues (see graphic, below).The researchers identified functional changes in the DNA of eight out of 13 Siglecs encoded by genes on chromosome 19 in humans, Neanderthals, and Denisovans. This hot spot of evolution appears only in Siglec gene variants, not in nearby genes on the chromosome, suggesting natural selection favored these changes, presumably because they helped fight pathogens that target Neu5Ac.Apes did not show these changes, says first author Naazneen Khan, an evolutionary biologist now at the University of Kentucky. Given the mutations' presence in archaic hominins, this burst of evolution must have happened before our lineages diverged 600,000 years ago, but after the mutation in that altered sialic acid arose more than 2 million years ago, perhaps in Homo erectus, thought to be an ancestor of modern humans and Neanderthals.Most Siglecs are found on immune cells, but in the new paper, the team reports that several of the human Siglecs that underwent evolutionary changes are expressed in other types of human cells, including some in the placenta, cervix, pancreas, gut, and brain. Siglec changes may have been a side effect of intense battles with pathogens that infected these tissues, Nissi Varki suggests.Although the recently mutated Siglecs protect us from pathogens, they may also contribute to other diseases. Some of the genetically changed Siglecs are associated with inflammation and autoimmune disorders such as asthma and with meningitis. The researchers suggest the altered Siglecs are constantly on high alert and do not dampen immune responses against our own tissues; they may even make some individuals more prone to the runaway inflammation seen in severe COVID-19.Gionfriddo, C.M., Stott, M.B., Power, J.F., Ogorek, J.M., Krabbenhoft, D.P., Wick, R., Holt, K., Chen, L.-X., Thomas, B.C., Banfield, J.F., Moreau, J.W., 2020. Genome-resolved metagenomics and detailed geochemical speciation analyses yield new insights into microbial mercury cycling in geothermal springs. Applied and Environmental Microbiology 86, e00176-20.: Geothermal systems emit substantial amounts of aqueous, gaseous, and methylated mercury, but little is known about microbial influences on mercury speciation. Here, we report results from genome-resolved metagenomics and mercury speciation analysis of acidic warm springs in the Ngawha Geothermal Field (<55°C, pH <4.5), Northland Region, Aotearoa New Zealand. Our aim was to identify the microorganisms genetically equipped for mercury methylation, demethylation, or Hg(II) reduction to volatile Hg(0) in these springs. Dissolved total and methylated mercury concentrations in two adjacent springs with different mercury speciation ranked among the highest reported from natural sources (250 to 16,000?ng liter?1 and 0.5 to 13.9?ng liter?1, respectively). Total solid mercury concentrations in spring sediments ranged from 1,274 to 7,000?μg g?1. In the context of such ultrahigh mercury levels, the geothermal microbiome was unexpectedly diverse and dominated by acidophilic and mesophilic sulfur- and iron-cycling bacteria, mercury- and arsenic-resistant bacteria, and thermophilic and acidophilic archaea. By integrating microbiome structure and metagenomic potential with geochemical constraints, we constructed a conceptual model for biogeochemical mercury cycling in geothermal springs. The model includes abiotic and biotic controls on mercury speciation and illustrates how geothermal mercury cycling may couple to microbial community dynamics and sulfur and iron biogeochemistry.Importance: Little is currently known about biogeochemical mercury cycling in geothermal systems. The manuscript presents a new conceptual model, supported by genome-resolved metagenomic analysis and detailed geochemical measurements. The model illustrates environmental factors that influence mercury cycling in acidic springs, including transitions between solid (mineral) and aqueous phases of mercury, as well as the interconnections among mercury, sulfur, and iron cycles. This work provides a framework for studying natural geothermal mercury emissions globally. Specifically, our findings have implications for mercury speciation in wastewaters from geothermal power plants and the potential environmental impacts of microbially and abiotically formed mercury species, particularly where they are mobilized in spring waters that mix with surface or groundwaters. Furthermore, in the context of thermophilic origins for microbial mercury volatilization, this report yields new insights into how such processes may have evolved alongside microbial mercury methylation/demethylation and the environmental constraints imposed by the geochemistry and mineralogy of geothermal systems.Gong, H., Zhu, C., Zhang, Y., Li, Z., San, Q., Xu, L., Li, Y., Dong, M., Hassanzadeh, H., 2020. Experimental evaluation on the oil saturation and movability in the organic and inorganic matter of shale. Energy & Fuels 34, 8063-8073. oil reservoirs are more complex and difficult to exploit than conventional and tight oil reservoirs because of low porosity, permeability, and rich organic matter. The presence of organic matter has great influence on the flow behaviors of oil in shale and the development methods for shale oil. In this work, the saturation and movability behaviors of oil in organic and inorganic matter of shale were investigated by experimental methods. First, vacuum-imbibition tests were carried out to evaluate the saturated oil amount at different states (in inorganic pores, organic pores, and adsorbed/dissolved in organic matter) in shale cores and to calculate the inorganic/organic saturation and inorganic/organic porosity. The results show that the imbibition volume of oil is 2.4–5.7 times as much as those of KCl solutions for the several shale cores. The excess of imbibition oil is adsorbed or dissolved into the organic matter and dispersed in the organic pores. The organic saturation of oil in the shale samples is from 58.9 to 82.6%, which is 1.4–4.7 times as much as that in inorganic matter. The inorganic porosity is from 1.9 to 4.4%, while the organic porosity is from 0.3 to 1.3%. Moreover, the oil movability under centrifugation in the organic and inorganic matter of shale was measured by nuclear magnetic resonance. The results show that the content of movable oil in inorganic pores is 20–80%, which is higher than that of organic matter with a value of lower than 10%. The total movable content of oil in shale is influenced greatly by the content of movable oil in organic matter. Therefore, how to displace the oil in organic matter is the main problem to be solved in developing shale oil.Grasby, S.E., Liu, X., Yin, R., Ernst, R.E., Chen, Z., 2020. Toxic mercury pulses into late Permian terrestrial and marine environments. Geology 48, 830–833. spikes in mercury (Hg) concentration are observed globally at the latest Permian extinction (LPE) horizon that are thought to be related to enhanced volcanic emissions of the Siberian Traps large igneous province (LIP). While forming an effective chemostratigraphic marker, it remains unclear whether such enhanced volcanic Hg emissions could have generated toxic conditions that contributed to extinction processes. To address this, we examined the nature of enhanced Hg emissions from the Siberian Traps LIP and the potential impact it may have had on global ecosystems during the LPE. Model results for a LIP eruption predict that pulses of Hg emissions to the atmosphere would have been orders of magnitude greater than normal background conditions. When deposited into world environments, this would have generated a series of toxic shocks, each lasting >1000 yr. Such repeated Hg loading events would have had severe impact across marine trophic levels, as well as been toxic to terrestrial plant and animal life. Such high Hg loading rates may help explain the co-occurrence of marine and terrestrial extinctions.Greenway, R., Barts, N., Henpita, C., Brown, A.P., Arias Rodriguez, L., Rodríguez Pe?a, C.M., Arndt, S., Lau, G.Y., Murphy, M.P., Wu, L., Lin, D., Tobler, M., Kelley, J.L., Shaw, J.H., 2020. Convergent evolution of conserved mitochondrial pathways underlies repeated adaptation to extreme environments. Proceedings of the National Academy of Sciences 117, 16424-16430.: Some organisms can tolerate environments lethal for most others, but we often do not know what adaptations allow them to persist and whether the same mechanisms underly adaptation in different lineages exposed to the same stressors. Investigating fish inhabiting springs rich in toxic H2S, we show that tolerance is mediated by the modification of pathways that are inhibited by H2S and those that can detoxify it. Sulfide spring fishes across multiple genera have evolved similar modifications of toxicity targets and detoxification pathways, despite abundant lineage-specific variation. Our study highlights how constraints associated with the physiological consequences of a stressor limit the number of adaptive solutions and lead to repeatable evolutionary outcomes across organizational and evolutionary scales.Abstract: Extreme environments test the limits of life; yet, some organisms thrive in harsh conditions. Extremophile lineages inspire questions about how organisms can tolerate physiochemical stressors and whether the repeated colonization of extreme environments is facilitated by predictable and repeatable evolutionary innovations. We identified the mechanistic basis underlying convergent evolution of tolerance to hydrogen sulfide (H2S)—a toxicant that impairs mitochondrial function—across evolutionarily independent lineages of a fish (Poecilia mexicana, Poeciliidae) from H2S-rich springs. Using comparative biochemical and physiological analyses, we found that mitochondrial function is maintained in the presence of H2S in sulfide spring P. mexicana but not ancestral lineages from nonsulfidic habitats due to convergent adaptations in the primary toxicity target and a major detoxification enzyme. Genome-wide local ancestry analyses indicated that convergent evolution of increased H2S tolerance in different populations is likely caused by a combination of selection on standing genetic variation and de novo mutations. On a macroevolutionary scale, H2S tolerance in 10 independent lineages of sulfide spring fishes across multiple genera of Poeciliidae is correlated with the convergent modification and expression changes in genes associated with H2S toxicity and detoxification. Our results demonstrate that the modification of highly conserved physiological pathways associated with essential mitochondrial processes mediates tolerance to physiochemical stress. In addition, the same pathways, genes, and—in some instances—codons are implicated in H2S adaptation in lineages that span 40 million years of evolution.Gresov, A.I., Sergienko, V.I., Yatsuk, A.V., Zarubina, N.V., Kalinchuk, V.V., 2020. Gas-geochemical parameters of bottom sediments in the northern part of the East Siberian Sea and Podvodnikov Basin of the Arctic Ocean. Doklady Earth Sciences 492, 382-386. data on the gas and chemical composition of bottom sediments of the marginal-shelf part of the East Siberian Sea, continental slope, and Podvodnikov Basin of the Arctic Ocean are presented. The genetic parameters of seven groups of epigenetic hydrocarbon gases are determined. The distribution areas of the potential oil–gas, gas–oil, and oil deposits have been revealed. Three groups of chemical elements have been specified in bottom sediments. Their maximum concentrations are related to particular geostructures of the area studied.Grettenberger, C.L., McCauley Rench, R.L., Gruen, D.S., Mills, D.B., Carney, C., Brainard, J., Hamasaki, H., Ramirez, R., Watanabe, Y., Amaral-Zettler, L.A., Ohmoto, H., Macalady, J.L., 2020. Microbial population structure in a stratified, acidic pit lake in the Iberian Pyrite Belt. Geomicrobiology Journal 37, 623-634. examined the geochemistry and bacterial and archaeal community structure in the acidic (pH < 2.4) pit lake at Pe?a de Hierro, near the headwaters of the Río Tinto. The lake has strong vertical gradients in light, O2, pH, conductivity, and dissolved ions. Bacterial and archaeal communities between 0 and 32?m displayed low species richness and evenness. Relatives of iron cycling taxa accounted for 60-90% of the operational taxonomic units (OTUs) throughout the water column. Relatives of heterotrophic, facultative Fe(III)-reducing species made up more than a third of the bacterial and archaeal community in the photic zone. Taxa related to Fe(II) oxidizers Ferrithrix thermotolerans and Acidithix ferrooxidans were also abundant in the photic zone. Below the photic zone, relatives of the lithoautotrophic Fe(II) oxidizers Leptospirillum ferrooxidans and Ferrovum myxofaciens bloomed at different depths within or just below the oxycline. Thermoplasmatales predominated in the deep, microoxic zone of the lake. The microbial population structure of the lake appears to be influenced by the production of oxygen and organic matter by phototrophs in a narrow zone at the lake surface and by strong geochemical gradients present in the water column that create distinct niches for separate Fe(II) oxidizers.Grettenberger, C.L., Sumner, D.Y., Wall, K., Brown, C.T., Eisen, J.A., Mackey, T.J., Hawes, I., Jospin, G., Jungblut, A.D., 2020. A phylogenetically novel cyanobacterium most closely related to Gloeobacter. The ISME Journal 14, 2142-2152. to the evolutionary steps producing innovations in oxygenic photosynthesis may be preserved in the genomes of organisms phylogenetically placed between non-photosynthetic Vampirovibrionia (formerly Melainabacteria) and the thylakoid-containing Cyanobacteria. However, only two species with published genomes are known to occupy this phylogenetic space, both within the genus Gloeobacter. Here, we describe nearly complete, metagenome-assembled genomes (MAGs) of an uncultured organism phylogenetically placed near Gloeobacter, for which we propose the name Candidatus Aurora vandensis {Au’ro.ra. L. fem. n. aurora, the goddess of the dawn in Roman mythology; van.de’nsis. N.L. fem. adj. vandensis of Lake Vanda, Antarctica}. The MAG of A. vandensis contains homologs of most genes necessary for oxygenic photosynthesis including key reaction center proteins. Many accessory subunits associated with the photosystems in other species either are missing from the MAG or are poorly conserved. The MAG also lacks homologs of genes associated with the pigments phycocyanoerethrin, phycoeretherin and several structural parts of the phycobilisome. Additional characterization of this organism is expected to inform models of the evolution of oxygenic photosynthesis.Guillemant, J., Lacoue-Nègre, M., Berlioz-Barbier, A., de Oliveira, L.P., Albrieux, F., Joly, J.-F., Duponchel, L., 2020. Evaluating the benefits of data fusion and PARAFAC for the chemometric analysis of FT-ICR MS data sets from gas oil samples. Energy & Fuels 34, 8195-8205. characterization of the products of the hydrotreatment of gas oils is of high interest for refiners and can be achieved using ultrahigh resolution mass spectrometry (FT-ICR MS). However, the analysis of gas oil samples by FT-ICR MS generates complex data sets with numerous variables whose exhaustive analysis requires the use of multivariate methods. Relevant information about nitrogen and sulfur compounds contained in several industrial gas oils are obtained by using three different ionization modes that are electrospray ionization (ESI) used in positive and negative polarities and atmospheric pressure photoionization (APPI) used in positive polarity. For data sets generated for a single ionization mode, classical multivariate methods such as Principal Component Analysis (PCA) are commonly used. When the key information is spread into several ionization modes and thus into several data sets, a data fusion approach is highly interesting to simultaneously explore these data sets and can be followed by Parallel Factor analysis (PARAFAC). Nevertheless, many more variables are simultaneously considered when data fusion is performed and the sensitivity of PARAFAC and its ability to extract the most relevant variables compared to classical multivariate methods has not been assessed yet in the framework of FT-ICR MS. In this paper, a comparison of the classical data analysis (PCA) approach and the data fusion combined with the PARAFAC analysis approach is presented. The results have shown that applying PARAFAC on fused data sets is highly sensitive and able to put forward features and variables that are individually identified through classical data analysis with greater ease of implementation and interpretation of results. As an example, dibenzothiophenes and carbazole families (DBE 9) have explained most of the variance between samples and remain the most refractory compounds in hydrotreated samples. A significant difference in alkylation between the different types of gas oils has also been spotted. This paper validates the power and efficiency of this approach to explore complex data sets simultaneously without any loss of significant information.Guo, J., Liao, H., 2020. In-situ formation of perylene in lacustrine sediments and its geochemical significance. Acta Geochimica 39, 587-594. identify the possible sources and formation mechanism of perylene in sediments, temporal trends of perylene and other polycyclic aromatic hydrocarbons, as well as the organic matters, were analyzed in sediment cores from Dianchi Lake and Sihailongwan Maar Lake in China. Significantly high concentrations of perylene were observed in both cores and increased gradually with the sediment depth. Source identification suggested that perylene in both cores were of primarily diagenetic origin, other than the anthropogenic inputs. Both terrigenous and aquatic organic matters could be the source of perylene in sediments and diagenetic formation of perylene in sediment is kinetically controlled by the microbial activities under anaerobic conditions. All evidence points to the fact that the formation of perylene in sediment should be an index of the microbial activities and environmental conditions, other than the source of specific organic matters or precursors. In addition, we should be cautious when using any geochemical indicators involving the microbial alternation.Guo, J., Zhang, M., Liu, J.a., Luo, R., Yan, T., Yang, T., Jiang, X., Dong, M., Yin, Y., 2020. Evaluation of the deterioration state of archaeological wooden artifacts: A nondestructive protocol based on direct analysis in real time – mass spectrometry (DART-MS) coupled to chemometrics. Analytical Chemistry 92, 9908-9915. the deterioration state of archeological wood is obligatory before the preservation of archeological wooden artifacts. Herein, a nondestructive, accurate, and rapid methodology is first developed via direct analysis in real time-mass spectrometry (DART-MS) with chemometrics to classify archeological wood and recent wood into 3 groups according to their deterioration states. As water in wooden artifacts probably affected the ion fragmentation process during DART-MS, ions responsible for evaluating the deterioration state were separately screened toward waterlogged archeological wood and dried archeological wood by partial least-squares discriminant analysis (PLS-DA). The well-defined separation of severely decayed archeological wood, moderately decayed archeological wood and recent wood was revealed in PLS-DA models. Twenty and 27 wood fragment ions were further screened as key variables to evaluate the deterioration state of waterlogged archeological wood and dried archeological wood, respectively. They were tentatively identified as ions of lignin monomeric compositions, lignin dimers, lignin trimers, and oligosaccharides. Results strongly suggested that differences in the structure and relative abundances of wood cell wall components accounts for the evaluation of deterioration state by DART-MS coupled to chemometrics. PLS-DA models provided R2Y = 0.836, Q2 = 0.817, and R2Y = 0.754, Q2 = 0.682 were then established separately using mass spectral fingerprints of respective potential predictive wood fragment ions. Furthermore, archeological woods, consisting of Castanopsis, Quercus, Idesia, Populus, and Cunninghamia species and with an average MWC range of 103–465%, were used as an external validation set and evaluated with the methodology developed herein and the MWC criteria. Results showed that DART-MS coupled to chemometrics could accurately predict the inhomogeneous deterioration states of archeological wooden artifacts and avoid the interference of inorganic deposits, in comparison with the MWC criteria.Guo, Q., Chen, X., Liuzhuang, X., Yang, Z., Zheng, M., Chen, N., Mi, J., 2020. Evaluation method for resource potential of shale oil in the Triassic Yanchang Formation of the Ordos Basin, China. Energy Exploration & Exploitation 38, 841-866. widely distributed, thick Chang 7 Shale is the richest shale oil formation in China. A calculation method for the evaporative hydrocarbon recovery coefficient based on formation volume factor is proposed considering the correction of heterogeneity-based total organic carbon differences to improve the adsorbed oil calculation method, and light hydrocarbon evaporative sampling losses, which can make mobile and total oil calculations more accurate. The adsorbed oil, S1 evaporative loss, total oil yield, and movable oil yield of 200 shale samples from the Chang 7 Member were calculated using the new methods. Results show that S1 evaporative loss accounts for 29% of S1, total oil yield is 3.5 times S1, and movable oil yield accounts for 37% of total oil yield. Based on the calculated total oil yield and movable oil yield results, the relationships among total oil yield, movable oil yield, and total organic carbon of the Chang 7 were established yielding total oil yield and movable oil yield estimates of 11.12?×?109?t and 4.01?×?109?t, respectively, revealing its tremendous shale exploration potential.Guo, Z., Huang, S., Wang, J., Feng, Y.-L., 2020. Recent advances in non-targeted screening analysis using liquid chromatography - high resolution mass spectrometry to explore new biomarkers for human exposure. Talanta 219, 121339. the last decade, advances related to high-resolution mass spectrometry (HRMS) have led to improved capabilities for non-targeted chemical analyses. Important applications for these capabilities include identifying unknown xenobiotics and discovering emerging contaminants in human samples as exposure biomarkers. Despite technological advances, identifying unknown compounds by non-targeted analyses remains challenging due in part to the lack of MS spectral libraries and inherent sample complexity resulting in the generation of large amounts of MS data. While high resolution can separate nominally isobaric compounds in a mass spectrum, isomers cannot be distinguished. Much work also remains to develop models to predict both mass spectra and retention times for the unexplored regions of chemical space. In this review, we focus on recent advances and applications of non-targeted analyses using liquid chromatography – high-resolution mass spectrometry (LC-HRMS) in human biomonitoring, including sample preparation, molecular formula assignments, and prediction models for retention times and mass fragmentations, to enable and improve identifications of unknown chemicals. The purpose of this review is to improve our understanding of the applicability and limitations in both the analytical methods and data analysis aspects of non-targeted analysis in human exposure studies. We also discuss the challenges and prospects in this field for future research on sample preparation, identification confidence and accuracy, data processing tools, MS spectra comparability, liquid chromatographic retention time (RT) prediction algorithms, and quantitative capabilities.Gutiérrez-Almada, K., González-Acosta, B., Borges-Souza, J.M., Aguila-Ramírez, R.N., 2020. Marine bacteria associated with shallow hydrothermal systems in the Gulf of California with the capacity to produce biofilm inhibiting compounds. Archives of Microbiology 202, 1477-1488. hydrothermal systems are extreme environments. The sediments and fluids emitted from the vents present unusual physical and chemical conditions compared to other marine areas, which promotes unique biodiversity that has been of great interest for biotechnology for some years. In this work, a bioprospective study was carried out to evaluate the capacity of bacteria associated with shallow hydrothermal vents to produce biofilm-inhibiting compounds. Degradation assays of N-acyl homoserine lactone (AHL) autoinducers (C6HSL) involved in the quorum sensing process were carried out on 161 strains of bacteria isolated from three shallow hydrothermal systems located in Baja California Sur (BCS), Mexico. The biosensor Chromobacterium violaceum CV026 was used. Twenty-three strains showed activity, and organic extracts were obtained with ethyl acetate. The potential of the extracts to inhibit the formation of biofilms was tested against two human pathogenic strains (Pseudomonas aeruginosa PAO1 and Aeromonas caviae ScH3), a shrimp pathogen (Vibrio parahaemolyticus M8), and two marine strains identified as producing biofilms on submerged surfaces (Virgibacillus sp C29 and Vibrio alginolyticus C96). The results showed that Vibrio alginolyticus and Brevibacillus thermoruber, as well as some thermotolerant strains (mostly Bacillus), produce compounds that inhibit bacterial biofilms (B. licheniformis, B. paralicheniformis, B. firmus, B. oceanizedimenis, B. aerius and B. sonorensis).Hafiz, M., Hakhoo, N., Bhat, G.M., Kanungo, S., Thusu, B., Craig, J., Ahmed, W., 2020. Source potential and reservoir characterization of the Cambay Shale, Cambay Basin, India: Implications for tight gas and tight oil resource development. American Association of Petroleum Geologists Bulletin 104, 1707-1749. organic–geochemical investigations of the Eocene Cambay Shale (Cambay Basin, India) from five wells and an open-cast lignite mine reveal that the total organic carbon ranges from 0.37 to 10.68 wt. %, with an average of 2.43 wt. %. The pseudo–Van Krevelen diagram, hydrogen index versus the maximum pyrolysis yield temperature (Tmax) crossplot, and the visual kerogen assessment of the Cambay Shale indicate the dominance of type III kerogen, with some well samples showing mixed type III and II kerogen. The vitrinite reflectance values range between 0.46% and 0.7%, with Tmax values ranging from 387°C to 441°C and are consistent with an immature to early oil generation stage. The dominance of vitrinite macerals and high pristane–phytane (Pr/Ph) ratios (>6) of the well samples indicate an oxic to dysoxic depositional environment, whereas the presence of Botryococcus braunii and low Pr/Ph ratios (<1) in the lignite mine samples suggesting a more reducing brackish water environment. The estimation of hydrocarbons generation, expulsion, and retention data suggest a low retention of 10%–12% of generated hydrocarbons within the Cambay Shale. The mineralogical data show an abundance of clay minerals (average 62.9%), implying poor to moderate mineral brittleness index. The kerogen type and maturity level along with the high clay content and poor to moderate brittleness indicate low fracability, thereby restricting the production potential of the Cambay Shale for tight gas or tight oil exploration.Hajiabadi, S.H., Bedrikovetsky, P., Mahani, H., Khoshsima, A., Aghaei, H., Kalateh-Aghamohammadi, M., Habibi, S., 2020. Effects of surface modified nanosilica on drilling fluid and formation damage. Journal of Petroleum Science and Engineering 194, 107559. the fact that hydrophobic nanosilica can improve the stability of water/oil emulsion, there exist controversies pertaining to its influence on oil-based drilling fluid rheological behavior and the subsequent formation damage. The present study addresses the above using a surface modified nanosilica, where the particles were functionalized with different silane-based groups to alter their hydrophilicity: 3-glycidoxypropyl-triethoxy silane (GPTS) and combined GPTS and propyl silane (PGPTS). The NPs were characterized through FTIR analysis, particle size, and zeta-potential measurements followed by flow behavior experiments, core-scale mud flow tests, Computed Tomography (CT) scanning and SEM imaging techniques to determine the mud penetration depth.We found that, depending on the type of functionalized group and the size of NPs, the surface modification of NPs can enhance the rheological properties and mitigate formation-damage. The most desirable behavior, both in terms of the plastic viscosity and yield stress, was achieved with 15 nm size NPs. The functionalized NP with the 3-glycidoxypropyl-triethoxy silane (GPTS@SiO2), which is less hydrophilic compared with bare NP, improved plastic viscosity of the drilling fluid, however slightly deteriorated the yield stress. This was compensated for by adding a double amount of GPTS on the surface of NP (DGPTS@SiO2), which was shown to be more effective than merely increasing the GPTS content in the drilling fluid. Further improvement of rheological properties was made by combining GPTS and propyl silane (PGPTS@SiO2); implying the positive effect of reducing hydrophilicity on both the plastic viscosity and yield stress. It is noteworthy that surface modifications were identified to be efficient below an optimal concentration of 1 wt% of NPs due to the lack of particle agglomeration. Moreover, a decreasing trend in plastic viscosity was observed against increasing temperature as a result of lowering viscosity of the continuous phase. Meanwhile, the yield stress experienced greater changes versus temperature due to the larger dependency of the interactions between drilling fluids components on temperature.In addition, the results were further validated through a series of core-flow tests which showed that with the aid of the nano-based drilling fluids (NDFs) containing DGPTS@SiO2 and GPTS@SiO2 the penetration depth of mud, thus the degree of internal formation damage can be significantly reduced.Hakimi, M.H., Abdullah, W.H., Lashin, A.A., Ibrahim, E.-K.H., Makeen, Y.M., 2020. Hydrocarbon generation potential of the organic-rich Naifa Formation, Say’un–Masila Rift Basin, Yemen: Insights from geochemical and palynofacies analyses. Natural Resources Research 29, 2687-2715. Say’un–Masila rift, one of the most important basins of Yemen, contains unconventional resources of organic-rich rocks. In the present work, geochemical and palynofacies analyses were performed on the organic-rich source rock (argillaceous limestone) of the late Jurassic–early Cretaceous Naifa Formation in the Say’un–Masila Rift Basin to investigate its hydrocarbon generation potential. The geochemical analysis of the organic matter reveals that the argillaceous limestone unit has total organic carbon contents of 0.5–2.6%, which indicate fair to good hydrocarbon source potential. The organic matter in the analyzed samples is dominated by Type II/III and Type III kerogens, with minor Type II kerogen, referring to both oil- and gas-prone source rocks. The dominant kerogen Types II/III and Type III are indicated further from quantitative results based on an open pyrolysis–gas chromatography analysis. Biological markers and palynofacies analysis suggest that the kerogen was formed through a combination of mixed marine and high land plant organic matter and was preserved under sub-oxic sedimentary conditions. The different geochemical and optical maturity parameters indicate that the analyzed argillaceous limestone of the Naifa Formation is thermally mature, equivalent to early mature of oil-generation window. This implies that the burial depth of the analyzed samples is not deep enough; therefore, only the deeper parts of the Naifa source rocks at the basin have reached a satisfactory maturity level to be considered as potentially effective petroleum source rock. The biomarker source and depositional environment indicators presented and discussed in this study are useful for future exploration in the Say’un–Masila Basin for oil-to-oil and oil-to-source geochemical correlations and offer guidance for potential prospecting targets that may occur within the basin.Hall, R.J., Whelan, F.J., McInerney, J.O., Ou, Y., Domingo-Sananes, M.R., 2020. Horizontal gene transfer as a source of conflict and cooperation in prokaryotes. Frontiers in Microbiology 11, 1569. doi: 10.3389/fmicb.2020.01569. gene transfer (HGT) is one of the most important processes in prokaryote evolution. The sharing of DNA can spread neutral or beneficial genes, as well as genetic parasites across populations and communities, creating a large proportion of the variability acted on by natural selection. Here, we highlight the role of HGT in enhancing the opportunities for conflict and cooperation within and between prokaryote genomes. We discuss how horizontally acquired genes can cooperate or conflict both with each other and with a recipient genome, resulting in signature patterns of gene co-occurrence, avoidance, and dependence. We then describe how interactions involving horizontally transferred genes may influence cooperation and conflict at higher levels (populations, communities, and symbioses). Finally, we consider the benefits and drawbacks of HGT for prokaryotes and its fundamental role in understanding conflict and cooperation from the gene-gene to the microbiome level.Hamzeh, M., Karimipour, F., 2020. Petroleum potential assessment using an optimized fuzzy outranking approach: A case study of the Red River petroleum system, Williston Basin. Energy Exploration & Exploitation 38, 960-988. paper presents a new approach, called optimized fuzzy Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE), based on combining fuzzy logic, an outranking method and the cuckoo search optimization algorithm to assess petroleum potential in a spatial framework. The approach brings together flexibility and simplicity to solve petroleum exploration problem under uncertainty using experts? knowledge and the information associated with the discovered oil pools simultaneously. The characteristics of the essential elements of the petroleum system are used as key criteria in the model. To exemplify the approach, a case study was undertaken in the Red River petroleum system of the Canadian portion of the Williston Basin. Eight datasets related to the selected criteria were integrated by the optimized fuzzy PROMETHEE to create a map that makes it possible to identify the areas of highest petroleum potential. All discovered oil pools in the Red River petroleum system were used in the verification process. The results indicated that the proposed approach can deal effectively with incomplete data and imprecise information, and can be efficiently used in petroleum exploration, thereby reducing the cost and risk of exploration.Han, H., Zhu, W., Song, Z., Huang, K., Li, H., Yue, M., 2020. The mechanism of the effect of Geobacillus stearothermophilu on crude oil. Petroleum Science and Technology 38, 517-523. study of the mechanism of endogenous microbial flooding in the reservoir, this paper analyzed the effect of microbial and its product on the stability of paraffin wax using Geobacillus stearothermophilu isolated from wells. GC-MS was adopted to investigate the degradation of crude oil by emulsified bacteria. A simulated reservoir environment created by micro-visualized two-dimensional glass model was used to identify mechanism of emulsified bacteria on remaining oil. Emulsified bacteria and their metabolite can greatly improve the efficiency of displacement process. Microorganisms can use crude oil and activator as the source of nutrition, facilitating its grow at the oil-water interface, thus creating a favorable wettability by means of degradation of residual oil. Emulsified bacteria and their metabolite can emulsify the crude oil into emulsion, whose large viscosity attribute to a lower oil-water interface force as well as an improved mobility ratio and in the end, an enlarged swept volume.Harris, A.J.T., Feuerborn, T.R., Sinding, M.-H.S., Nottingham, J., Knudsen, R., Rey-Iglesia, A., Schmidt, A.L., Appelt, M., Gr?nnow, B., Alexander, M., Eriksson, G., Dalén, L., Hansen, A.J., Lidén, K., 2020. Archives of human-dog relationships: Genetic and stable isotope analysis of Arctic fur clothing. Journal of Anthropological Archaeology 59, 101200. Indigenous populations of the Arctic, domestic dogs (Canislupus familiaris) were social actors aiding in traction and subsistence activities. Less commonly, dogs fulfilled a fur-bearing role in both the North American and Siberian Arctic. Examples of garments featuring dog skins were collected during the 19th-20th centuries and are now curated by the National Museum of Denmark. We sequenced the mitochondrial genomes of macroscopically identified dog skin garments. We conducted stable carbon and nitrogen isotope ratio analysis of the dog furs and of fur samples from contemporaneous pelts of Arctic (C. lupus arctos) and grey (C. lupus) wolves. Despite the presence of biocides used to protect the fur clothing during storage, we extracted well-preserved DNA using a minimally-invasive sampling protocol. Unexpectedly, the mtDNA genomes of one-third of the samples were consistent with wild taxa, rather than domestic dogs. The strong marine component in the diets of North American dogs distinguished them from Greenland and Canadian wolves, but Siberian dogs consumed diets that were isotopically similar to wild species. We found that dog provisioning practices were variable across the Siberian and North American Arctic, but in all cases, involved considerable human labor.Harris, P.T., 2020. The fate of microplastic in marine sedimentary environments: A review and synthesis. Marine Pollution Bulletin 158, 111398. review of 80 papers on microplastic (MP) particles in marine sediments was conducted for different sedimentary environments. The papers were assessed for data on average MP concentration, MP morphotype (fibres, fragments, films, etc.), MP particle size distribution, sediment accumulation rates and correlations with total organic carbon (TOC) and sediment grain size. The median concentration of MP particles is highest in fjords at 7000 particles kg?1 dry sediment (DS) followed by 300 in estuarine environments, 200 in beaches, 200 in shallow coastal environments, 50 on continental shelves and 80 particles kg?1 DS for deep sea environments. Fibres are the dominant MP type and account for 90% of MP on beaches (median value) and 49% of particles in tide-dominated estuaries. In order to advance our understanding of the fate of MP in the ocean, quantitative assessments are needed of MP flux rates (g m?2 year?1) in a range of sedimentary environments.Haruda, A.F., Ventresca Miller, A.R., Paijmans, J.L.A., Barlow, A., Tazhekeyev, A., Bilalov, S., Hesse, Y., Preick, M., King, T., Thomas, R., H?rke, H., Arzhantseva, I., 2020. The earliest domestic cat on the Silk Road. Scientific Reports 10, 11241. present the earliest evidence for domestic cat (Felis catus L., 1758) from Kazakhstan, found as a well preserved skeleton with extensive osteological pathologies dating to 775–940 cal CE from the early medieval city of Dzhankent, Kazakhstan. This urban settlement was located on the intersection of the northern Silk Road route which linked the cities of Khorezm in the south to the trading settlements in the Volga region to the north and was known in the tenth century CE as the capital of the nomad Oghuz. The presence of this domestic cat, presented here as an osteobiography using a combination of zooarchaeological, genetic, and isotopic data, provides proxy evidence for a fundamental shift in the nature of human-animal relationships within a previously pastoral region. This illustrates the broader social, cultural, and economic changes occurring within the context of rapid urbanisation during the early medieval period along the Silk Road.Hatayama, K., 2020. Manganese carbonate precipitation induced by calcite-forming bacteria. Geomicrobiology Journal 37, 603-609. dissimilatory metal-reducing bacteria and a halophilic bacterium are able to induce manganese carbonate (rhodochrosite) precipitation. In this study, it was revealed that Ensifer adhaerens JCM 21105T, Microbacterium testaceum JCM 1353T, Pseudomonas protegens DSM 19095T, and Rheinheimera texasensis DSM 17496T, which are calcite-forming bacteria, were able to aerobically induce the precipitation of manganese carbonate crystals on an agar medium. In the case of all four strains, the principal morphology of the precipitated manganese carbonate crystals was that of micro-sized spheres, when they were aerobically cultivated over the entire surface of the agar medium at 28?°C for 7?days.He, C., Zhong, H., Zhang, Y., Li, Y., Chung, K.H., Fang, L., Zhang, W., Wu, B., Xu, C., Shi, Q., 2020. Organic matter in delayed coking wastewater: Molecular composition and its effect on emulsification. Fuel 279, 118432. coking is a common resid conversion process used in refining operations. A large amount of oil-containing wastewater is produced during the hydraulic decoking process. The coking wastewater contains emulsions which are difficult to process in water treatment plants, especially when the coker is fed with feedstocks have high content of heteroatoms. This study examined the molecular composition of emulsified oil and dissolved organic matter (DOM) in coking wastewater. The emulsification agents in coking wastewater were identified. The emulsified oil and DOM were separated and enriched by liquid–liquid extraction, solid phase extraction, and adsorption chromatography, and then characterized by gas chromatography-mass spectrometry and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry analyses. The results showed that the emulsified oil and DOM in coking wastewater contained highly condensed molecules with a large number of nitrogen and oxygen heteroatomic compounds. The OxSy surfactants and their derivatives, polyoxyethylene ether, and the strong polar oxygen-, nitrogen-, and sulfur-containing compounds are likely the oil–water emulsification agents.He, L., Ma, Y., Yue, C., Wu, J., Li, S., 2020. Kinetic modeling of Kukersite oil shale pyrolysis with thermal bitumen as an intermediate. Fuel 279, 118371. this work, the kinetics of oil shale pyrolysis was studied in a fixed bed retort with thermal bitumen as an intermediate. Kukersite oil shale samples were tested at temperatures ranging from 300 to 480 °C at the constant heating rate of 1 °C·min?1. Weights of kerogen, thermal bitumen, shale oil and gases were measured as functions of the final pyrolysis temperature, which were simulated using a first-order reactions in series model under non-isothermal conditions. The obtained kinetic parameters were also proven to accurately describe the experimental results. The proportional factors for products (fB = 0.658, fO1 = 0.183, fO2 = 0.890, fG1 = 0.157, fG2 = 0.106) indicate that kerogen decomposition mainly generates thermal bitumen accounting for 65.8% of total composed kerogen, and that thermal bitumen further degrades and mostly produces shale oil occupying 89.0% of total degraded thermal bitumen. Activation energies and pre-exponential parameters for the two steps are: 126.12 and 192.77 kJ·mol?1, 1.66 × 107 and 1.08 × 1012 s?1, respectively.Henry, I.A., Netzer, R., Davies, E.J., Brakstad, O.G., 2020. Formation and fate of oil-related aggregates (ORAs) in seawater at different temperatures. Marine Pollution Bulletin 159, 111483. this study, the formation and fate of oil-related aggregates (ORAs) from chemically dispersed oil in seawater (SW) were investigated at different temperatures (5?°C, 13?°C, 20?°C). Experiments in natural SW alone, and in SW amended with typical marine snow constituents (phytoplankton and mineral particles), showed that the presence of algae stimulated the formation of large ORAs, while high SW temperature resulted in faster aggregate formation. The ORAs formed at 5?°C and 13?°C required mineral particles for sinking, while the aggregates also sank in the absence of mineral particles at 20°. Early in the experimental periods, oil compound accumulation in ORAs was faster than biodegradation, particularly in aggregates with algae, followed by rapid biodegradation. High abundances of bacteria associated with hydrocarbon biodegradation were determined in the ORAs, together with algae-associated bacteria, while clustering analyses showed separation between bacterial communities in experiments with oil alone and oil with algae/mineral particles.Hill, R.A., Connolly, J.D., 2020. Triterpenoids. Natural Product Reports 37, 962-998. 2015. Previous review: Nat. Prod. Rep., 2018, 35, 1294–1329 This review covers the isolation and structure determination of triterpenoids reported during 2015 including squalene derivatives, lanostanes, holostanes, cycloartanes, cucurbitanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, serratanes, isomalabaricanes and saponins; 320 references are cited.Homza, T.X., Fillerup, M.A., Gardner, D.W., 2020. Toward a better understanding of northern Alaska’s petroleum systems: Deconstructing the Barrow arch. American Association of Petroleum Geologists Bulletin 104, 1793-1816. more than 60 yr, the term “Barrow arch” has been used to describe a regional structural high beneath northern Alaska and the Beaufort and Chukchi Seas that is of chief importance to the area’s petroleum systems. However, there are multiple interpretations of what, precisely, constitutes the Barrow arch. For example, most, but not all, interpretations invoke the arch as a basement feature. Other interpretations refer to a Barrow arch that existed in different forms at widely variant times, from the early Paleozoic to the present, and although many authors refer to the feature as “composite” or “complex,” the arch is normally drawn on maps as a single lineation. Numerous meanings of the term Barrow arch have been conflated in the literature resulting in some contradictory usages; this paper is an attempt to clarify the nomenclature.Six primary usages of the term Barrow arch are identified in this paper. These are the (1) basement high, (2) ancestral highlands, (3) rift margin, (4) Lower Cretaceous unconformity antiform, (5) Brookian sill, and (6) dip reversal usages. These usages are deconstructed herein, and other names of more exacting definitions are introduced.These newly defined terms are the “basement arch,” “Ellesmerian highlands,” “rift shoulders,” “northern Alaska anticlinorium,” and “Colville rim.” “Basement subcrop areas” are introduced as regions where basement rocks were eroded to a peneplain beneath unconformities; these help to isolate the various northern Alaskan rift shoulders. It is recommended that the term Barrow arch be discarded. The northern Alaska anticlinorium is the most significant newly defined feature for northern Alaska’s petroleum systems.Hou, J., Sievert, S.M., Wang, Y., Seewald, J.S., Natarajan, V.P., Wang, F., Xiao, X., 2020. Microbial succession during the transition from active to inactive stages of deep-sea hydrothermal vent sulfide chimneys. Microbiome 8, 102.: Deep-sea hydrothermal vents are highly productive biodiversity hotspots in the deep ocean supported by chemosynthetic microorganisms. Prominent features of these systems are sulfide chimneys emanating high-temperature hydrothermal fluids. While several studies have investigated the microbial diversity in both active and inactive sulfide chimneys that have been extinct for up to thousands of years, little is known about chimneys that have ceased activity more recently, as well as the microbial succession occurring during the transition from active to inactive chimneys.Results: Genome-resolved metagenomics was applied to an active and a recently extinct (~?7?years) sulfide chimney from the 9–10° N hydrothermal vent field on the East Pacific Rise. Full-length 16S rRNA gene and a total of 173 high-quality metagenome assembled genomes (MAGs) were retrieved for comparative analysis. In the active chimney (L-vent), sulfide- and/or hydrogen-oxidizing Campylobacteria and Aquificae with the potential for denitrification were identified as the dominant community members and primary producers, fixing carbon through the reductive tricarboxylic acid (rTCA) cycle. In contrast, the microbiome of the recently extinct chimney (M-vent) was largely composed of heterotrophs from various bacterial phyla, including Delta-/Beta-/Alphaproteobacteria and Bacteroidetes. Gammaproteobacteria were identified as the main primary producers, using the oxidation of metal sulfides and/or iron oxidation coupled to nitrate reduction to fix carbon through the Calvin-Benson-Bassham (CBB) cycle. Further analysis revealed a phylogenetically distinct Nitrospirae cluster that has the potential to oxidize sulfide minerals coupled to oxygen and/or nitrite reduction, as well as for sulfate reduction, and that might serve as an indicator for the early stages of chimneys after venting has ceased.Conclusions: This study sheds light on the composition, metabolic functions, and succession of microbial communities inhabiting deep-sea hydrothermal vent sulfide chimneys. Collectively, microbial succession during the life span of a chimney could be described to proceed from a “fluid-shaped” microbial community in newly formed and actively venting chimneys supported by the oxidation of reductants in the hydrothermal fluid to a “mineral-shaped” community supported by the oxidation of minerals after hydrothermal activity has ceased. Remarkably, the transition appears to occur within the first few years, after which the communities stay stable for thousands of years.Hou, L., Ma, W., Luo, X., Liu, J., 2020. Characteristics and quantitative models for hydrocarbon generation-retention-production of shale under ICP conditions: Example from the Chang 7 member in the Ordos Basin. Fuel 279, 118497. with varying TOC content (0.5–26%) from the seventh member of the Triassic Yanchang Formation (abbreviated as Chang 7 shale) were artificially matured via semi-open pyrolysis to systematically study the characteristics of hydrocarbon generation, retention, and production under in-situ conversion process (ICP) conditions. The results show that with increasing Ro, the quantities of both generated oil and gas present an S-shape increase trend, with their generation rates reaching the maximum at 0.9 %Ro and 1.1 %Ro, respectively. The retention quantity and capability of oil and gas of shales first increase and then decrease as a function of thermal severity. With increasing TOC, larger amounts of oil and gas are retained, but the retention capability of the shale decreases. The shale simultaneously retains the largest amount of oil during the maximum oil generation period. The quantities of produced oil and gas share the same variation trend with the that of generated oil and gas, and the maximum oil and gas production rates are consistent with maximum generation rates. The greater the TOC, the greater the shale production potential. With increasing thermal maturity, the oil production potential of shales decreases slowly and then becomes relatively steady, while the gas production potential first changes slightly and subsequently decline rapidly. Based on the oil and gas generation-retention-expulsion characteristics, quantitative prediction models as a function of TOC and Ro are established, which will contribute to future engineering of the ICP.Hrebien, V., Deschaseaux, E., Eyre, B.D., 2020. Isoprene flux from permeable carbonate sediments on the Great Barrier Reef. Marine Chemistry 225, 103856. is the most abundant biogenic volatile organic compound (BVOC) on the planet, with annual emissions accounting for up to half of all BVOC emissions. Isoprene has been measured extensively in terrestrial habitats where it is highly abundant; however, there is limited knowledge on marine systems where it is found at lower concentrations. Here, we report for the first time isoprene fluxes from coral reef permeable carbonate sediments with a cover of microphytobenthos (MPB) from Heron and Lizard Islands, on the southern and northern ends of the Great Barrier Reef, respectively. Using advective and diffusive benthic chambers, we measured isoprene fluxes over full diel cycles on both islands. Net effluxes of isoprene from the sediment to the water column were observed at both Heron Island (mean: 10.0 ± 1.1 nmol m2 h?1) and Lizard Island (mean: 3.9 ± 0.9 nmol m2 h?1). Light isoprene fluxes were much higher on Heron Island than on Lizard Island and both islands had lower isoprene emissions in the dark. Higher isoprene fluxes during the day reflects the role of MPB photosynthesis in isoprene production. Lower isoprene fluxes at night is most likely due to isoprene consumption by microbial activity or less production in the absence of photosynthesis. The contribution of benthic isoprene emissions from coral reef carbonate sands worldwide (0.52 Gg C y?1) were estimated to represent less than 0.005% of the global marine atmospheric fluxes (11,600 Gg C y?1).Hu, H., Xing, X., Wang, J., Ren, H., 2020. Characterization of dissolved organic matter in reclaimed wastewater supplying urban rivers with a special focus on dissolved organic nitrogen: A seasonal study. Environmental Pollution 265, Part B, 114959. study investigated the seasonal characterization of dissolved organic matter (DOM) in reclaimed wastewater (RW) with a special focus on dissolved organic nitrogen (DON) from two full-scale municipal wastewater reclamation plants (WRPs) where the produced RW was used to augment urban rivers. Results showed that the concentrations of DON in RW ranged from 0.32?mg/L to 1.21?mg/L. A higher seasonal mean value of DON in RW from both of the WRPs was observed in winter (p?<?0.05, ANOVA). DON chemical characteristics analysis, including ultrahigh-resolution mass spectrometry and ultrafiltration fractionation, showed that DON in RW exhibits more lability during winter than during the other three seasons. This finding was also supported by the results of an algal bioassay experiment, in which DON bioavailabilities were 63.7?±?3.0%, 53.0?±?5.3%, 49.5?±?0.5%, and 49.8?±?0.2% for WRP-A and were 60.8?±?2.4%, 43.7?±?2.2%, 41.2?±?1.7%, and 43.1?±?1.1% for WRP-B in winter, spring, summer, and autumn, respectively. Accordingly, DON in RW during winter is more prone to stimulate natural algae and microorganisms, which gives rise to eutrophication in urban rivers. At the molecular level, the seasonal changes in DON are not coupled with those of DOC, which highlights the necessity of DON measurement to obtain a comprehensive understanding of the seasonal characteristics of DOM in RW and its effect on wastewater reuse in urban rivers.Hu, R., Tan, J., Dick, J., Li, L., Wang, W., 2020. Quantification of the influences of radiolarian fossils on the pore structure of Wufeng-Lungmachi gas shales (Ordovician-Silurian) in the Sichuan Basin, South China. Journal of Natural Gas Science and Engineering 81, 103442. the differences among shale pore systems is crucial to exploring the enrichment mechanism of shale gas. In this study, we found that radiolarian micro-fossils are widely distributed in the overmature marine organic-rich Wufeng-Lungmachi formations surrounding the Sichuan Basin, South China. This enables an investigation on the full-scale pore structure characteristics of the two formations by using a combination of qualitative methods (field emission scanning electron microscopy (FE-SEM)) and quantitative methods (low-pressure N2 and CO2 adsorption and high-pressure mercury intrusion porosimetry (MIP)). The results show that micropores (accounting for 75.81%) and mesopores (accounting for 63.56%) are mainly responsible for the total surface area and the total pore volume, respectively. Furthermore, organic matter significantly contributes to the shale surface area, and the intercrystalline pores of clay minerals make an important contribution to the pore volume of shale. Abundant biological pores can be discovered in radiolarian fossils, and these biological pores belong to mesopores and macropores. The investigation of gas adsorption shows that radiolarian-poor shale reflects the presence of slit-shaped pores, while radiolarian-rich shale indicates the presence of ink-bottle-shaped pores. In addition, despite similar TOC contents, clay minerals and brittle minerals, radiolarian-rich layers have larger pore volumes than radiolarian-poor layers. The results calculated using the threshold method with ImageJ software show that the average surface porosities of the organic matter, mineral matrix, and radiolarians are 15.69%, 1.84%, and 5.34%, respectively. Given that the quantitative calculation results in a greater contribution by the pores developed in radiolarians, the biological pores developed in radiolarians are beneficial for the enrichment of free gas.Huang, C., Ju, Y., Zhu, H., Lash, G.G., Qi, Y., Yu, K., Feng, H., Ju, L., Qiao, P., 2020. Investigation of formation and evolution of organic matter pores in marine shale by helium ion microscope: An example from the Lower Silurian Longmaxi Shale, South China. Marine and Petroleum Geology 120, 104550. a helium ion microscope (HIM), we carefully observed and analyzed organic matter (OM) pores in several Longmaxi shale samples collected from the Upper Yangtze Platform, South China. The results indicate that the formation process of OM pore essentially involves gradual expansion and connection of defects/space within OM. This process, which is divided into the four stages of formation, expansion, connection, and consolidation, can involve pore scales ranging from a few nanometers to over a micrometer under HIM. More specifically, spotted spherical pores first form within OM, then expand until they connect to adjacent pores. Within large areas of such connectivity, “pit” structures eventually form, preliminarily defined as OM pores that are significantly larger than surrounding pores, essentially being greater than 100 nm in size. As the final stage of OM pore evolution, the shape and size of “pit” structures can be limited by the framework of mineral particles around or within the OM. Additionally, we found that surrounding pores are smaller when “pit” structures develop, perhaps because removal of side chains of OM tends to occur on the inner surface of the formed pores, leading them to rapidly expand, or because OM particles have differing compositions or structures, some of which may be unfavorable to pore development.Huang, R.-J., Yang, L., Shen, J., Yuan, W., Gong, Y., Guo, J., Cao, W., Duan, J., Ni, H., Zhu, C., Dai, W., Li, Y., Chen, Y., Chen, Q., Wu, Y., Zhang, R., Dusek, U., O’Dowd, C., Hoffmann, T., 2020. Water-insoluble organics dominate brown carbon in wintertime urban aerosol of China: Chemical characteristics and optical properties. Environmental Science & Technology 54, 7836-7847. chromophores responsible for light absorption in atmospheric brown carbon (BrC) are not well characterized, which hinders our understanding of BrC chemistry, the links with optical properties, and accurate model representations of BrC to global climate and atmospheric oxidative capacity. In this study, the light absorption properties and chromophore composition of three BrC fractions of different polarities were characterized for urban aerosol collected in Xi’an and Beijing in winter 2013–2014. These three BrC fractions show large differences in light absorption and chromophore composition, but the chromophores responsible for light absorption are similar in Xi’an and Beijing. Water-insoluble BrC (WI-BrC) fraction dominates the total BrC absorption at 365 nm in both Xi’an (51 ± 5%) and Beijing (62 ± 13%), followed by a humic-like fraction (HULIS-BrC) and high-polarity water-soluble BrC. The major chromophores identified in HULIS-BrC are nitrophenols and carbonyl oxygenated polycyclic aromatic hydrocarbons (OPAHs) with 2–3 aromatic rings (in total 18 species), accounting for 10% and 14% of the light absorption of HULIS-BrC at 365 nm in Xi’an and Beijing, respectively. In comparison, the major chromophores identified in WI-BrC are PAHs and OPAHs with 4–6 aromatic rings (in total 16 species), contributing 6% and 8% of the light absorption of WI-BrC at 365 nm in Xi’an and Beijing, respectively.Huerta, N.J., Cantrell, K.J., White, S.K., Brown, C.F., 2020. Hydraulic fracturing to enhance injectivity and storage capacity of CO2 storage reservoirs: Benefits and risks. International Journal of Greenhouse Gas Control 100, 103105. potential CO2 storage reservoirs have been found to have insufficient porosity and permeability to support cost effective commercial-scale injection. As a result, the use of hydraulic fracturing to enhance injectivity and storage capacity of CO2 storage reservoirs was explored. Previous modeling studies indicate that fracturing can increase storage capacity by modest to significant amounts (10%–35%), depending on model assumptions. Simulations completed as part of this study confirm that for a range of horizontal well lengths, number of fractures, fracture geometries, and fracture properties, injectivity is improved and capacity increases by 13%–71% over the base case unfractured vertical well. Intuitively, increasing the well length and number of fractures had a corresponding impact on increased capacity. Fracture area (i.e., the fracture height multiplied by its width) was an important parameter for increasing capacity but the specific geometry (e.g., the ratio of height-to-width) was unimportant. The most important aspect that affected capacity was the ability of a fracture to connect high permeability horizontal zones in the reservoir. This would allow a single well to access both layers, thereby maximizing total storage capacity of the reservoir while likely leading to an overall increase of the CO2 footprint, which is an important consideration for Class VI UIC permitting. The results of this work demonstrate that hydraulic fracturing is an attractive option to consider when faced with an underperforming geologic carbon storage site that is at risk of causing a project to fail.Huo, Z., Tang, X., Meng, Q., Zhang, J., Li, C., Yu, X., Yang, X., 2020. Geochemical characteristics and hydrocarbon expulsion of lacustrine marlstones in the Shulu Sag, Bohai Bay Basin, eastern China: Assessment of tight oil resources. Natural Resources Research 29, 2647-2669. recent years, tight oil exploration has made significant progress in the lower part of Shahejie Formation (Es L 3 Es3L) in the Shulu Sag, Bohai Bay Basin, Eastern China, which shows good exploration prospects for tight oil. However, accurate evaluation of tight oil resource potential is influenced by a lack of studies and an incomplete understanding of hydrocarbon expulsion from marlstone source rocks. This study investigated the geological and geochemical characteristics of marlstone source rocks, their hydrocarbon generation and expulsion, and the tight oil resource. Results show that the marlstone source rocks were deposited in a reducing to weakly oxidizing lacustrine environment with low-middle salinity, distributed widely in the central and southern troughs, with the maximum thickness greater than 700 m. The marlstone source rocks have relatively high organic matter abundance (0.06–7.97% of total organic carbon content with an average value of 1.51%), are dominated by type II and I kerogen, and are at the immature to mature stage (0.3%?<?vitrinite reflectance (VR)?<?0.8%), which reveals fair–good source rocks for the marlstones. The threshold and peak of hydrocarbon expulsion for marlstone source rocks are at 0.51% VR and 0.6% VR, respectively. The amounts of generation and expulsion from marlstone source rocks are 19.72?×?108 t and 8.53?×?108 t, respectively, with an expulsion efficiency of 43%. The total tight oil resource in place is 10.9?×?108 (5.8?×?108 t within the carbonate rudstone reservoir and 5.1?×?108 t within the marlstone reservoir), indicating a significant tight oil potential and promising exploration prospect in the Shulu Sag, Bohai Bay Basin, Eastern China.Hylling, O., Carstens, A.B., Kot, W., Hansen, M., Neve, H., Franz, C.M.A.P., Johansen, A., Ellegaard-Jensen, L., Hansen, L.H., 2020. Two novel bacteriophage genera from a groundwater reservoir highlight subsurface environments as underexplored biotopes in bacteriophage ecology. Scientific Reports 10, 11879. bacteriophages are central entities in bacterial ecology and population dynamics, there is currently no literature on the genomes of bacteriophages isolated from groundwater. Using a collection of bacterial isolates from an aquifer as hosts, this study isolated, sequenced and characterised two bacteriophages native to the groundwater reservoir. Host phylogenetic analyses revealed that the phages targeted B. mycoides and a novel Pseudomonas species. These results suggest that both bacteriophages represent new genera, highlighting that groundwater reservoirs, and probably other subsurface environments as well, are underexplored biotopes in terms of the presence and ecology of bacteriophages.Italiano, F., Solecki, A., Martinelli, G., Wang, Y., Zheng, G., 2020. New applications in gas geochemistry. Geofluids 2020, 4976190. present in the Earth crust are important in various branches of human activities. Hydrocarbons are a significant energy resource, helium is applied in many high-tech instruments, and studies of crustal gas dynamics provide insight in the geodynamic processes and help monitor seismic and volcanic hazards. Quantitative analysis of methane and CO2 migration is important for climate change studies. Some of them are toxic (H2S, CO2, CO); radon is responsible for the major part of human radiation dose. The development of analytical techniques in gas geochemistry creates opportunities of applying this science in numerous fields. Noble gases, hydrocarbons, CO2, N2, H2, CO, and Hg vapor are measured by advanced methods in various environments and matrices including fluid inclusions. Following the “Geochemical Applications of Noble Gases”(2009), “Frontiers in Gas Geochemistry” (2013), and “Progress in the Application of Gas Geochemistry to Geothermal, Tectonic and Magmatic Studies” (2017) published as special issues of Chemical Geology and “Gas geochemistry: From conventional to unconventional domains” (2018) published as a special issue of Marine and Petroleum Geology, this volume continues the tradition of publishing papers reflecting the diversity in scope and application of gas geochemistry.Jaber, S., Joly, M., Brissy, M., Leremboure, M., Khaled, A., Ervens, B., Delort, A.-M., 2020. Biotic and abiotic transformation of amino acids in cloud water: Experimental studies and atmospheric implications. Biogeosciences Discussions 2020, 1-27. interest for organic nitrogen and particularly for quantifying and studying the fate of amino acids (AA) has been growing in the atmospheric science community. However very little is known about biotic and abiotic transformation mechanisms of amino acids in clouds. In this work, we measured the biotransformation rates of 18 amino acids with four bacterial strains (Pseudomonas graminis PDD-13b-3, Rhodococcus enclensis PDD-23b-28, Sphingomonas PDD-32b-11 and Pseudomonas syringae PDD-32b-74) isolated from cloud water and representative of this environment. At the same time, we also determined the abiotic (chemical, OH radical) transformation rates within the same solutions mimicking the composition of cloud water. We used a new approach by UPLC-HRMS to quantify free AA directly in the artificial cloud water medium without concentration and derivatization.The experimentally-derived transformation rates were used to compare their relative importance under atmospheric conditions and compared to the chemical loss rates based on kinetic data of amino acid oxidation in the aqueous phase. This analysis shows that previous estimates overestimated the abiotic degradation rates, and thus underestimated the lifetime of amino acids in the atmosphere as they only considered loss processes but did not take into account the potential transformation of amino acids into each other.Jacob-Lopes, E., Queiroz, M.I., Maroneze, M.M., Zepka, L.Q., 2020. Handbook of Microalgae-Based Processes and Products. Fundamentals and Advances in Energy, Food, Feed, Fertilizer, and Bioactive Compounds. Elsevier, Academic Press, p. 936. Handbook of Microalgae-based Processes and Products provides a complete overview of all aspects involved in the production and utilization of microalgae resources at commercial scale. Divided into four parts (fundamentals, microalgae-based processes, microalgae-based products, and engineering approaches applied to microalgal processes and products), the book explores the microbiology and metabolic aspects of microalgae, microalgal production systems, wastewater treatment based in microalgae, CO2 capture using microalgae, microalgae harvesting techniques, and extraction and purification of biomolecules from microalgae. It covers the largest number of microalgal products of commercial relevance, including biogas, biodiesel, bioethanol, biohydrogen, single-cell protein, single-cell oil, biofertilizers, pigments, polyunsaturated fatty acids, bioactive proteins, peptides and amino acids, bioactive polysaccharides, sterols, bioplastics, UV-screening compounds, and volatile organic compounds. Moreover, it presents and discusses the available engineering tools applied to microalgae biotechnology, such as process integration, process intensification, and techno-economic analysis applied to microalgal processes and products, microalgal biorefineries, life cycle assessment, and exergy analysis of microalgae-based processes and products.The coverage of a broad range of potential microalgae processes and products in a single volume makes this handbook an indispensable reference for engineering researchers in academia and industry in the fields of bioenergy, sustainable development, and high-value compounds from biomass, as well as graduate students exploring those areas. Engineering professionals in bio-based industries will also find valuable information here when planning or implementing the use of microalgal technologies.Key Features??Covers theoretical background information and results of recent research. ??Discusses all commercially relevant microalgae-based processes and products. ??Explores the main emerging engineering tools applied to microalgae processes, including techno-economic analysis, process integration, process intensification, life cycle assessment, and exergy analyses.Part 1: FundamentalsChapter 1 - Microalgae biotechnology: A brief introduction, Yusuf Chisti, Pages 3-23Chapter 2 - Morphophysiological, structural, and metabolic aspects of microalgae, Maria Isabel Queiroz, Juliana Guerra Vieira and Mariana Manzoni Maroneze, Pages 25-48Chapter 3 - Microalgae culture collections, strain maintenance, and propagation, Sergio de Oliveira Louren?o, Pages 49-84Chapter 4 - Synthetic biology applied to microalgae-based processes and products, Dinesh Kumar Saini, Sunil Pabbi, ... Pratyoosh Shukla, Pages 85-98Part 2: Microalgae-Based ProcessesChapter 5 - Photobioreactor design, Jose C. Merchuk, Pages 101-126Chapter 6 - Microalgae production systems, Francisco Gabriel Acién Fernández, José María Fernández-Sevilla, , Bernardo Llamas Moya, Emilio Molina Grima, Pages 127-163Chapter 7 - Wastewater treatment based in microalgae. Alfredo de Jesús Martínez-Roldán and Rosa Olivia Ca?izares-Villanueva, Pages 165-184Chapter 8 - Carbon dioxide capture and utilization using microalgae, Patricia Ruiz-Ruiz, Adrián Estrada and Marcia Morales, Pages 185-206Chapter 9 - Dewatering and drying of algal cultures, Jaison Jeevanandam and Michael Kobina Danquah, Pages 207-224Chapter 10 - Microalgae harvesting techniques, Ana Filipa Esteves, Cíntia Jesus Almeida, Ana Luísa Gon?alves, José Carlos Pires, Pages 225-281Chapter 11 - Extraction of biomolecules from microalgae, Yulin Hu and Amarjeet Bassi, Pages 283-308Part 3: Microalgae-Based ProductsChapter 12 - Biogas from microalgae, Bárbara Rincón, Pages 311-328Chapter 13 - Biodiesel from microalgae, Zheting Bi and Brian He, Pages 329-371Chapter 14 - Bioethanol production from microalgae, Didem ?z?imen, An?l Tevfik Ko?er, Benan ?nan, Tugba ?zer, Pages 373-389Chapter 15 - Biohydrogen from microalgae, Harshita Singh and Debabrata Das, Pages 391-418Chapter 16 - Microalgae single cell oil, Yusuf Nazir, Hafiy Halim, Pranesha Prabhakaran, Aidil Abdul Hamid, Yuanda Song, Pages 419-444Chapter 17 - Microalgal bio-fertilizers, Arun Kumar and Jay Shankar Singh, Pages 445-463Chapter 18 - Pigments from microalgae, Fernando Pagels, Daniel Salvaterra, Helena Melo Amaro, Ana Catarina Guedes, Pages 465-492Chapter 19 - Nutritional quality and bioactive properties of proteins and peptides from microalgae, Caleb Acquah, Sean M. Tibbetts, Sharadwata Pan, Chibuike Udenigwe, Pages 493-531Chapter 20 - Bioactive polysaccharides from microalgae, Nastasia Prybylski, Claire Toucheteau, Hicham El Alaoui, Nicolas Bridiau, Thierry Maugard, Slim Abdelkafi, Imen Fendri, Cédric Delattre, Pascal Dubessay, Guillaume Pierre, Philippe Michaud, Pages 533-571Chapter 21 - Sterols from microalgae, Mariane Bittencourt Fagundes, Raquel Guidetti Vendruscolo and Roger Wagner, Pages 573-596Chapter 22 - “Bioplastics from microalgae”—Polyhydroxyalkanoate production by cyanobacteria, Martin Koller, Pages 597-645Chapter 23 - UV-screening from microalgae, Ana Lucía Morocho-Jácome, Eleane de Almeida Cezare-Gomes, Jo?o Carlos Monteiro de Carvalho, Rafael Sauce, Catarina Rosado, Maria Valéria Robles Velasco, André Rolim Baby, Pages 647-657Chapter 24 - Volatile organic compounds from microalgae, Karem Rodrigues Vieira, Pricila Nass Pinheiro and Leila Queiroz Zepka, Pages 659-686Chapter 25 - Microalgae as enzymes biofactories, Michele Rigon Spier, Bianca Peron-Schlosser, Luana Cristina Paludo, Luis Alberto Gallo-García, Cristina Maria Zanette, Pages 687-706Part 4: Engineering Approaches Applied to Microalgal Processes and ProductsChapter 26 - Process integration applied to microalgae-based systems, Ihana Aguiar Severo, Mariany Costa Deprá, Rosangela Rodrigues Dias, Eduardo Jacob-Lopes, Pages 709-735Chapter 27 - Process intensification applied to microalgae-based processes and products. Rajshree Amrut Patil, Shankar Balajirao Kausley, Saurabh Milind Joshi, Aniruddha Bhalchandra Pandit, Pages 737-769Chapter 28 - Microalgal biorefineries, Alice Ferreira and Luisa Gouveia, Pages 771-798Chapter 29 - The bioeconomy of microalgae-based processes and products, Mauro Vigani, Pages 799-821Chapter 30 - Life cycle assessment of microalgae-based processes and products, Lucas Reijnders, Pages 823-840Chapter 31 - Exergy analysis applied to microalgae-based processes and products, Karina A. Ojeda, Eduardo Sánchez-Tuirán, Jose Gonzalez-Diaz, Manuel Gomez-Ochoa, Vyacheslav Kafarov, Pages 841-859Chapter 32 - Scale-up of microalgae-based processes, Niels-Henrik Norsker, Pages 861-883Index, Pages 885-905Jafarbeigi, E., Kamari, E., Salimi, F., Mohammadidoust, A., 2020. Experimental study of the effects of a novel nanoparticle on enhanced oil recovery in carbonate porous media. Journal of Petroleum Science and Engineering 195, 107602. of the effective methods in the process of enhancing the oil recovery from oil reservoirs is the use of nanotechnology. For this purpose, a new nanofluid was used to enhance the oil recovery from the reservoir at the scale of carbonate rocks. Finally, the obtained compound, in the first stage, nano-graphene oxide (NGO) were synthesized using Hummer's method and then they were subjected to surface modifications under new compounds. Finally, the obtained compound was known as (graphene oxide (N-(1-naphthyl) ethylenediamine)) (G-NEA), where G stands for graphene oxide (GO). Also, to determine the morphological characteristics and structure of the synthesized nanoparticles, Field Emission Scanning Electron Microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), and Transmission electron microscopy (TEM) were performed. In addition, zeta-potential analysis was performed to investigate the stability of nanofluids at different pHs. In order to investigate the effect of nanofluids on oil recovery, three concentrations (200, 400, and 500 ppm) of G-NEA nanofluids were prepared. Also, the interfacial-tension (IFT) measurement and rock angle measurement in the presence of nanofluid were investigated using a pendant drop and sessile drop method, respectively. The coreflood experiment was performed to evaluate the effect of G-NEA nanofluid on carbonate plugs. The results showed that when the G-NEA nanofluid concentration increased, the IFT value of 19.34 (mN/m) for deionized water to 10.8 (mN/m) for 500 ppm G-NEA and the contact angle decreased from the initial value of 166° to 40°, indicating the tendency of the wettability alteration of the rock to a water-wet conditions. The results of the coreflood experiment showed that at 400 and 500 ppm concentrations, the G-NEA nanofluid enhanced the oil recovery by 23 and 15%, respectively. Therefore, this synthesized nanofluid can have an effective approach to drive the carbonate reservoir rock into a water-wet condition and enhance oil recovery.Jansen, E., Christensen, J.H., Dokken, T., Nisancioglu, K.H., Vinther, B.M., Capron, E., Guo, C., Jensen, M.F., Langen, P.L., Pedersen, R.A., Yang, S., Bentsen, M., Kj?r, H.A., Sadatzki, H., Sessford, E., Stendel, M., 2020. Past perspectives on the present era of abrupt Arctic climate change. Nature Climate Change 10, 714-721. climate change is a striking feature of many climate records, particularly the warming events in Greenland ice cores. These abrupt and high-amplitude events were tightly coupled to rapid sea-ice retreat in the North Atlantic and Nordic Seas, and observational evidence shows they had global repercussions. In the present-day Arctic, sea-ice loss is also key to ongoing warming. This Perspective uses observations and climate models to place contemporary Arctic change into the context of past abrupt Greenland warmings. We find that warming rates similar to or higher than modern trends have only occurred during past abrupt glacial episodes. We argue that the Arctic is currently experiencing an abrupt climate change event, and that climate models underestimate this ongoing warming.Jautzy, J.J., Savard, M.M., Dhillon, R.S., Bernasconi, S.M., Smirnoff, A., 2020. Clumped isotope temperature calibration for calcite: Bridging theory and experimentation. Geochemical Perspectives Letters 14, 36-41. isotopes (Δ47) analysis in carbonates is becoming widespread across the geochemical community as a geothermometer that also allows for the reconstruction of the precipitating fluid δ18O composition. While initial Δ47–temperature relationship discrepancies between laboratories have been considerably reduced over the past 10 years, theoretical temperature calibration and laboratory experimental efforts have still not converged to common ground. Moreover, a lack of high temperature anchor points has weakened its application to high temperature calcite formation. Here we present a temperature calibration for carbonate clumped isotopes between 5 and 726 °C, using synthetically precipitated and heated calcites, to extend the calcite Δ47–temperature calibration to higher temperatures. By showing a strong agreement between the empirical calibration proposed here, theoretical and all recently published T–calibrations made using a full carbonate referencing scheme, this study: (1) provides a calibration allowing more precise application in high temperature geological systems, (2) further supports the improvement of inter-laboratory comparison by using carbonate standards, (3) reconciles empirical temperature calibrations with theory.Ji, H., Deng, H., Lu, H., Zhang, Z., 2020. Predicting a molecular fingerprint from an electron ionization mass spectrum with deep neural networks. Analytical Chemistry 92, 8649-8653. ionization–mass spectrometry (EI-MS) hyphenated to gas chromatography (GC) is the workhorse for analyzing volatile compounds in complex samples. The spectral matching method can only identify compounds within the spectral database. In response, we present a deep-learning-based approach (DeepEI) for structure elucidation of an unknown compound with its EI-MS spectrum. DeepEI employs deep neural networks to predict molecular fingerprints from an EI-MS spectrum and searches the molecular structure database with the predicted fingerprints. We evaluated DeepEI with MassBank spectra, and the results indicate DeepEI is an effective identification method. In addition, DeepEI can work cooperatively with database spectral matching and NEIMS (fingerprint to spectrum method) to improve identification accuracy.Jiang, L., Ding, W., George, S.C., 2020. Late Cretaceous–Paleogene palaeoclimate reconstruction of the Gippsland Basin, SE Australia. Palaeogeography, Palaeoclimatology, Palaeoecology 556, 109885. Cretaceous–Paleogene palaeovegetation and palaeoclimate in the Gippsland Basin was reconstructed using vascular plant-derived biomarkers, and are consistent with other proxy evidence for palaeoclimate (e.g. spore-pollen assemblages and plankton foraminifera oxygen isotopes). Variation in the higher plant-derived aliphatic and aromatic sesquiterpenoids, diterpenoids and triterpenoids resulted from vegetation succession, and is different in the T. lilliei, F. longus, L. balmei, M. diversus, P. asperopolus and N. asperus palynological biozones. Analyses of the oleanane index, the higher plant parameter, the higher plant index, the higher plant fingerprint, and various aliphatic and aromatic angiosperm/gymnosperm indices indicate the late Cretaceous–Paleogene (ca. 80–40 Ma) palaeoclimate in the Gippsland Basin was initially warm (Campanian T. lilliei Biozone), and then changed in this way: → cool (Maastrichtian upper F. longus Biozone), → warm (Paleocene L. balmei Biozone), → hot (early Eocene M. diversus and P. asperopolus Biozones), → warm and then cool (middle Eocene N. asperus Biozone). This changing climate trend is mostly consistent with global climate changes. In comparison to the analogous Taranaki Basin (western New Zealand), the Gippsland Basin is inferred to have had a less gymnosperm-dominated rainforest and a warmer climate in the late Cretaceous. During the Paleogene the palaeoclimate was similar in the two basins, as deduced from the angiosperm/gymnosperm indices of the sedimentary rocks.Jiang, Y., Dong, W., Xin, F., Jiang, M., 2020. Designing synthetic microbial consortia for biofuel production. Trends in Biotechnology 38, 828-831. microbial consortia could efficiently produce biofuels from lignocellulose through labor division between different species. However, the incompatible growth conditions between lignocellulose degraders and biofuel producers might limit the overall conversion efficiency. We discuss recent examples of biofuel production using microbial consortia and suggest steps toward realistic implementation.Jin, D.-Q., Shi, S.-W., Ma, Y., Fang, Q., 2020. LC-Swan probe: An integrated in situ sampling interface for liquid chromatography separation and mass spectrometry analysis. Analytical Chemistry 92, 9214-9222. situ sampling mass spectrometry (MS) systems can achieve rapid analysis of samples, while most of them do not have the pretreatment capability of chromatographic separation. This Article describes the design, fabrication, and application of a swan-shaped in situ sampling MS probe with liquid chromatography (LC) separation capacity. The LC-Swan probe was fabricated based on a single capillary with a micrometer-sized hole at its U-shaped bottom for sampling, a monolithic column for separation, and a tapered tip for electrospray. Four functions including in situ sampling, sample injection, chromatographic separation, and MS electrospray were integrated in the LC-Swan probe. Direct sampling and contacting–dissolution–injection sampling modes were developed to perform in situ sampling and injection of liquid samples and dry spot samples, respectively, in the high flow-resistance LC system. A pressing–sealing method was also developed using a polydimethylsiloxane (PDMS) sealer to achieve the sealing of the probe sampling hole during the high-pressure chromatographic separation process. The LC-Swan probe-based system exhibited effective desalting capacity in the analysis of angiotensin II with similar relative standard deviations (RSDs) of retention time and peak area below 3% and 19% (n = 3) for both salt-containing and salt-free samples. The present system was applied for analyzing cytochrome C digest to test its separation capability for samples with complex compositions, and 19 peptides were detected in 13 min with an amino acid coverage of 85%. We also applied the system in metabolite analysis of mouse organ sections of brain, liver, and kidney to preliminarily demonstrate its application potential in MS imaging analysis.Johnson, D.L., Grossman, E.L., Webb, S.M., Adkins, J.F., 2020. Brachiopod δ34SCAS microanalyses indicate a dynamic, climate-influenced Permo-Carboniferous sulfur cycle. Earth and Planetary Science Letters 546, 116428. isotopic studies of sulfate in carbonate minerals (carbonate associated sulfate; CAS) suggested that carbonates can provide a reliable, well-dated archive of the marine sulfur cycle through time. However, subsequent research has shown that diagenetic alteration can impose highly heterogeneous CAS sulfur isotopic compositions (δ34SCAS) among different carbonate phases within sediments. Such alteration necessitates targeted sampling of well-preserved, primary carbonate phases. Here, we present a new record of Carboniferous and Early Permian brachiopod δ34SCAS generated from over 130 measurements of microsampled brachiopod shells. Our record refines existing brachiopod δ34SCAS records and confirms a large, ～6.5‰ δ34SCAS decrease in the Early Carboniferous. Importantly, the record also features a novel 3–5‰ increase in δ34SCAS near the Serpukhovian-Bashkirian boundary (323.4 Ma) that coincides with carbonate δ13C and δ18O increases. Variability in δ34SCAS is minor both within (≤0.3‰) and among (≤2‰) individual co-depositional brachiopod specimens. A taxon-specific δ34SCAS offset is present one species (Composita subtilita) that also exhibits a δ13C offset, supporting the existence of biological “vital effects” on δ34SCAS. Geologic evidence and mathematical modeling of the Permo-Carboniferous carbon and sulfur cycles suggest that changes in the burial ratio of organic carbon to pyrite sulfur (RC:S) are insufficient to explain the observed mid-Carboniferous δ34SCAS record. We find that changes in the 34S depletion of pyrite relative to seawater sulfate (34ε) or in the δ34S of the input to the ocean (δ34Sin) are also needed. Large additions of O2 from organic carbon burial during the Permo-Carboniferous cannot be entirely compensated for with sulfur cycle changes; lower than modern late Visean pO2 and/or additional O2 sinks are needed to keep pO2 at plausible levels. Based on the geologic context surrounding our record's mid-Carboniferous δ34SCAS increase, we advocate for simultaneous changes in pyrite burial, 34ε, and δ34Sin, driven by sea level or tectonically induced changes in environments of sulfur burial, as a viable mechanism to produce rapid seawater δ34S changes.Jongejans, L.L., Mangelsdorf, K., Schirrmeister, L., Grigoriev, M.N., Maksimov, G.M., Biskaborn, B.K., Grosse, G., Strauss, J., 2020. n-Alkane characteristics of thawed permafrost deposits below a thermokarst lake on Bykovsky Peninsula, northeastern Siberia. Frontiers in Environmental Science 8, 118. doi: 10.3389/fenvs.2020.00118. permafrost thaw by thermokarst mobilizes previously frozen organic matter (OM) down to tens of meters deep within decades to centuries, leading to microbial degradation and greenhouse gas release. Late Pleistocene ice-rich Yedoma deposits that thaw underneath thermokarst lakes and refreeze after lake drainage are called taberal sediments. Although widespread, these have not been the subject of many studies. To study OM characteristics and degradability in thawed Yedoma, we obtained a 31.5 m long core from beneath a thermokarst lake on the Bykovsky Peninsula, northeastern Siberia. We reported radiocarbon ages, biogeochemical parameters [organic carbon (OC) content and bulk carbon isotopes] and n-alkane distributions. We found the most degraded OM in frozen, fluvial sediments at the bottom of the core, as indicated by the lowest n-alkane odd-over-even predominance (OEP; 2.2). Above this, the thawed Yedoma sediments had an n-alkane distribution typical of emergent vegetation, suggesting a landscape dominated by low-centered polygons. These sediments were OC poor (OC content: 0.8 wt%, 60% of samples < 0.1 wt%), but the OM (OEP～5.0) was better preserved than in the fluvial sediments. The upper part of the Yedoma reflected a transition to a drier, grass dominated environment. Furthermore, this unit’s OM was least degraded (OEP～9.4). The thermokarst lake that formed about 8 cal ka BP thawed the Yedoma in the talik and deposited Holocene lake sediments containing well-preserved OM (OEP～8.4) with the highest n-alkane concentrations (20.8 μg g–1 sediment). Old, allochthonous OM was found in the thawed Yedoma and frozen fluvial deposits. Using an n-alkane endmember model, we identified a mixed OM input in all units. In our study, the thawed Yedoma sediments contained less OC than reported in other studies for still frozen Yedoma. The Yedoma OM was more degraded compared to previous biomarker research on frozen Yedoma. However, this signal is overprinted by the input signal. The fluvial deposits below the Yedoma contained more OM, but this OM was more degraded, which can be explained by the OM input signal. Continued talik deepening and expansion of this thermokarst lake and others similar to it will expose OM with heterogeneous properties to microbial degradation.Jubb, A.M., Birdwell, J.E., Hackley, P.C., Hatcherian, J.J., Qu, J., 2020. Nanoscale molecular composition of solid bitumen from the Eagle Ford group across a natural thermal maturity gradient. Energy & Fuels 34, 8167-8177. solid bitumen is a petrographically defined secondary organic matter residue produced during petroleum generation and subsequent oil transformation. The presence of solid bitumen impacts many reservoir properties including porosity, permeability, and hydrocarbon generation and storage, among others. Furthermore, solid bitumen reflectance is an important parameter for assessing the thermal maturity of formations with little to no vitrinite. While the molecular composition of solid bitumen will strongly impact associated parameters such as the development of organic matter porosity, hydrocarbon generation, and optical reflectance, assessing the molecular composition of solid bitumen in situ within shale reservoirs can be challenging due to the small grain sizes (often ≤1 μm in diameter) and the inherent heterogeneity of shale formations. Here we employ the recently developed atomic force microscopy based infrared spectroscopy (AFM-IR) technique to investigate solid bitumen molecular composition in situ within shale samples from the Late Cretaceous Eagle Ford Group. These samples possess sulfur-rich type II kerogens that span a natural thermal maturity gradient from early oil generation to the dry gas window. The application of AFM-IR allows for the rapid collection of thousands of compositional measurements from solid bitumen with ～50 nm resolution. Our results indicate that (i) solid bitumen from the lower Eagle Ford displays both intra- and intergranular variation in the relative abundance of CH2, C═C, and C═O moieties present; (ii) this molecular variation tends to, but does not always, decrease with an increase in thermal maturity; and (iii) the solid bitumen composition between samples, from an atomic ratio perspective, is more similar than analysis of bulk kerogen isolates would indicate. These findings are discussed with perspective toward understanding the impact of thermal stress on the composition of secondary organic matter within the Eagle Ford Shale and highlight the growing awareness that organic matter heterogeneity within petroliferous mudrocks extends down to the nanoscale regime.Judd, A., Noble-James, T., Golding, N., Eggett, A., Diesing, M., Clare, D., Silburn, B., Duncan, G., Field, L., Milodowski, A., 2020. The Croker Carbonate Slabs: extensive methane-derived authigenic carbonate in the Irish Sea—nature, origin, longevity and environmental significance. Geo-Marine Letters 40, 423-438. Croker Carbonate Slabs, in the UK sector of the Irish Sea, has shallow (70 to 100 m) water, strong (>?2 knot) tidal currents, coarse mobile surficial sediments and the most extensive methane-derived authigenic carbonate (MDAC) known in European waters. Multi-disciplinary studies (2004 to 2015) were commissioned specifically to document the benthic habitat, and have resulted in the designation of this site as a Marine Protected Area (MPA) under the European Commission’s Habitats Directive as an example of “Submarine structures formed by leaking gases”. However, this paper is focussed on the geoscience aspects of the site: the mineralogy and isotopic composition of the MDAC, its formation and age. It considers the implications of these findings with respect to the timing of the deglaciation of the area since the Last Glacial Maximum (LGM), and the environmental implications of the seepage of methane from the site over a period of at least 17,000 years. Carbon isotope ratios (δ13 C ??34 to ??54‰) confirm that the carbonate minerals (high-Mg calcite and aragonite) result from the anaerobic oxidation of methane. Widespread shallow gas within post-glacial sediments is sourced from underlying coal-bearing Carboniferous strata. Geophysical (side-scan sonar and multi-beam echo sounder) and visual surveys show that the MDAC occurs as isolated lumps, continuous pavements, and cliffs <?6 m tall, which post-date the post-glacial sediments, but are in places covered by a veneer of coarse mobile surficial sediments. U-Th dates (17,000?±?5500 to 4000?±?200 BP) suggest continual MDAC formation since the last glacial maximum, and constrain the postglacial sea level rise in this part of the Irish Sea; the site must have been submarine before MDAC formation started, whether or not methane was escaping. Visual and acoustic evidence of gas seepage is limited, but methane concentrations in the water are high (<?21.4 nmol l?1) and suggest present-day export to the atmosphere. It is also implied that significant methane release to the atmosphere occurred immediately after the retreat of the ice that covered the site during the LGM until 21.9 to 20.7 ka BP.Kaal, J., Martínez Cortizas, A., Mateo, M.-?., Serrano, O., 2020. Deciphering organic matter sources and ecological shifts in blue carbon ecosystems based on molecular fingerprinting. Science of The Total Environment 742, 140554. carbon ecosystems (BCE) play an essential role in the global carbon cycle by removing atmospheric carbon dioxide and storing it as organic carbon (OC) in biomass and sediments. However, organic matter (OM) deposition and degradation/preservation processes are poorly understood, especially on the long-term and at molecular scales. We analysed sediment samples from six cores collected in tidal marshes, mangroves and seagrasses (up to 150?cm long cores spanning up to 10,000?yrs of OC accumulation) from Spencer Gulf (South Australia), by pyrolysis (Py-GC–MS and THM-GC–MS), and we compared the results with elemental and stable isotope data, to decipher OM provenance and to assess degradation/preservation dynamics. The results showed that: (1) the major biopolymers preserved were polysaccharides, polyphenolic moieties (lignin and tannin) and polymethylenic moieties (e.g. cutin, suberin, chlorophyll) with smaller apportions of proteins and resins; (2) the OM originates predominantly from vascular plant materials (in particular lignocellulose) that have been well-preserved, even in some of the oldest sediments; (3) mangroves were found to be the most efficient OC sinks, partially explained by syringyl lignin preservation; (4) seagrasses were shown to store polysaccharide-enriched OM; (5) large proportions of polycyclic aromatic hydrocarbons (PAHs) in surficial tidal marsh and mangrove sediments probably reflect pyrogenic OM from industrial combustion, and; (6) “ecosystem shifts”, i.e. mangrove encroachment in tidal marsh and transition from seagrass to mangrove, were detected. Deposition environment and source vegetation control OC sequestration and there is no specific recalcitrant form of OM that is selectively preserved. For the first time, we demonstrate how analytical pyrolysis in combination with stable isotope analysis can be used to reconstruct (palaeo-)ecological shifts between different BCE. This study improves our knowledge on OC accumulation dynamics and the response of BCE to environmental change, which can inform the implementation of strategies for climate change mitigation.Kalousová, K., Sotin, C., 2020. The insulating effect of methane clathrate crust on Titan's thermal evolution. Geophysical Research Letters 47, e2020GL087481.: Saturn's largest moon Titan is unique for its dense, methane‐rich atmosphere, with ongoing complex organics chemistry, and the hydrocarbon lakes and seas on its frigid surface. Titan also harbors a subsurface water ocean, and its ice shell is likely capped by a thick crust of low‐conductivity methane clathrates that are very stable under Titan's surface conditions. Here, we investigate the effect of this insulating clathrate crust on convection in the ice shell. Without the clathrate crust, convection occurs below a stagnant lid that is a few tens of kilometers thick and limits the exchange between the surface and the deep ocean. We show that a 5–10?km thick clathrate crust reduces the stagnant lid thickness about threefold thus increasing the potential for the ocean‐surface exchange. Moreover, the insulating effect of clathrates dramatically decreases the amount of extracted heat thus limiting the freezing rate of Titan's ocean.Plain Language Summary: The Cassini mission has revealed that Titan is an active icy moon with organic molecules forming in its atmosphere and a climate characterized by methane rains. Titan also harbors a deep ocean that decouples the ice shell from the inner solid layers. Methane and water ice react to form clathrate hydrate that acts as a thermal insulator. Previous one‐dimensional models of Titan's thermal evolution suggested the formation of a clathrate crust early in Titan's history, before the ice shell started to crystallize. Here, we follow with two‐dimensional numerical simulations of thermal convection in the ice shell that take into account the insulating effect of a clathrate crust. We show that the lithosphere thickness is reduced significantly thus providing a pathway for the exchange between the surface and the ocean. In addition, the amount of heat transferred by convection is reduced, which limits the freezing rate of Titan's ocean. The clathrate crust destabilization by impacts or cryovolcanism can also provide the methane needed to replenish the atmosphere. Titan's methane cycle significantly influences the ice shell structure and its dynamics thus playing a role similar to water on the Earth which not only shapes its surface but also affects its interior dynamics.Kammerer, C.F., Nesbitt, S.J., Flynn, J.J., Ranivoharimanana, L., Wyss, A.R., 2020. A tiny ornithodiran archosaur from the Triassic of Madagascar and the role of miniaturization in dinosaur and pterosaur ancestry. Proceedings of the National Academy of Sciences 117, 17932-17936.: Reptiles of the Mesozoic Era are known for their remarkable size: dinosaurs include the largest known land animals, and their relatives, the pterosaurs, include the largest creatures to ever fly. The origins of these groups are poorly understood, however. Here, we present a species (Kongonaphon kely) from the Triassic of Madagascar close to the ancestry of dinosaurs and pterosaurs, providing insight into the early evolution of those groups. Kongonaphon is a surprisingly small animal (estimated height, ～10 cm). Analysis of ancestral body size indicates that there was a pronounced miniaturization event near the common ancestor of dinosaurs and pterosaurs. Tiny ancestral body size may help explain the origins of flight in pterosaurs and fuzzy integument in both groups.Abstract: Early members of the dinosaur–pterosaur clade Ornithodira are very rare in the fossil record, obscuring our understanding of the origins of this important group. Here, we describe an early ornithodiran (Kongonaphon kely gen. et sp. nov.) from the Mid-to-Upper Triassic of Madagascar that represents one of the smallest nonavian ornithodirans. Although dinosaurs and gigantism are practically synonymous, an analysis of body size evolution in dinosaurs and other archosaurs in the context of this taxon and related forms demonstrates that the earliest-diverging members of the group may have been smaller than previously thought, and that a profound miniaturization event occurred near the base of the avian stem lineage. In phylogenetic analysis, Kongonaphon is recovered as a member of the Triassic ornithodiran clade Lagerpetidae, expanding the range of this group into Africa and providing data on the craniodental morphology of lagerpetids. The conical teeth of Kongonaphon exhibit pitted microwear consistent with a diet of hard-shelled insects, indicating a shift in trophic ecology to insectivory associated with diminutive body size. Small ancestral body size suggests that the extreme rarity of early ornithodirans in the fossil record owes more to taphonomic artifact than true reflection of the group’s evolutionary history.Kang, J., Fu, X., Elsworth, D., Liang, S., 2020. Impact of nitrogen injection on pore structure and adsorption capacity of high volatility bituminous coal. Energy & Fuels 34, 8216-8226. is often injected into coalbed methane (CBM) reservoirs to enhance the recovery by maintaining reservoir pressure and elevating permeability. Its effectiveness as a stimulant relies on impacts to the pore structure and related adsorption capacity of the coal reservoir. We quantify these changes in high volatility bituminous coal from Xinjiang, China, in response to nitrogen injection. Changes in pore size distribution (PSD) were characterized by high-pressure mercury injection (HPMI), low-pressure nitrogen gas adsorption (LP-N2GA), and carbon dioxide gas adsorption (LP-CO2GA). Corresponding changes in post-treatment adsorption capacity were measured by low-field nuclear magnetic resonance (LF-NMR) and isothermal adsorption. The specific pore volume and surface area of macropores (>50 nm), mesopores (2–50 nm), and micropores (<2 nm) all increased following nitrogen injection, as did measured adsorption capacity. These observations are consistent with an increase in surface area and improved connection between macropores that were previously unconnected or poorly connected. Nitrogen was subsequently diffused into mesopores and micropores, and then adsorbed into the pore walls. Nitrogen adsorption decreases surface energy and develops internal stress by differential deformation of the different macerals, that destroys the connectivity of mesopores and micropores. The effect of nitrogen injection on specific pore volume, surface area, and adsorption capacity also differs for different material and reservoir conditions. Higher mineral content and even distribution of macerals may improve the effect of PSD and adsorption capacity change. The presence of water hinders both flow and adsorption of nitrogen, leaving the mesopores unaffected by nitrogen injection. Water has little effect on changes in micropore architecture as a result of nitrogen injection due to capillary exclusion.Kang, J., Fu, X., Elsworth, D., Liang, S., 2020. Vertical heterogeneity of permeability and gas content of ultra-high-thickness coalbed methane reservoirs in the southern margin of the Junggar Basin and its influence on gas production. Journal of Natural Gas Science and Engineering 81, 103455. (>15?m) is one of the unique features of coalbed methane (CBM) reservoirs in Junggar basin, Xinjiang, China. However, there are few studies on the vertical permeability and gas content heterogeneity of ultra-high-thickness reservoirs. We use the Fukang west block on the southern margin of the Junggar Basin as a characteristic-example. Logging data describe the vertical distributions of the permeability and gas content of ultra-high-thickness CBM reservoirs. Flow modeling is used to explore the influence of those vertical heterogeneity on gas production. The results show that there is clear heterogeneity of these two parameters across the reservoir - from top to base - with different functional variabilities at shallow, intermediate and deep burial depths. At shallow depth (800–1100?m) the heterogeneity is controlled mainly by the increasing geo-stress and coalification. Permeability gradually decrease from the reservoir top to the base due to depth-increasing stress while gas content gradually increases due to permeability and depth-increasing degree of coalification. At intermediate depths (1100–1500?m) these two parameters show no particular trend. At the deep depths (1500–2000m) the reverse trend is observed as permeability increase from the reservoir top to the base while gas content gradually decreases. This heterogeneity is of great significance in the evaluation of the reserve, the recoverable resource and in the optimization of gas production. Neglecting the vertical heterogeneity of gas content across the seam results in a mis-estimation of ~4.4% of the recoverable resource with a 40% chance of exceeding this mis-estimation if only a single sample within the seam is used. The vertical heterogeneity exerts a significant influence on gas production, and the influence will be greater when the reservoirs with larger gas content. Production optimization favors perforation of separated rather than adjacent stages.Kantnerová, K., Yu, L., Zindel, D., Zahniser, M.S., Nelson, D.D., Tuszon, B., Nakagawa, M., Toyoda, S., Yoshida, N., Emmenegger, L., Bernasconi, S.M., Mohn, J., 2020. First investigation and absolute calibration of clumped isotopes in N2O by mid-infrared laser spectroscopy. Rapid Communications in Mass Spectrometry 34, e8836.: Unravelling the biogeochemical cycle of the potent greenhouse gas nitrous oxide (N2O) is an underdetermined problem in environmental sciences due to the multiple source and sink processes involved, which complicate mitigation of its emissions. Measuring the doubly isotopically substituted molecules (isotopocules) of N2O can add new opportunities to fingerprint and constrain its cycle. Methods: We present a laser spectroscopic technique to selectively and simultaneously measure the eight most abundant isotopocules of N2O, including three doubly substituted species – so called “clumped isotopes”. For the absolute quantification of individual isotopocule abundances, we propose a new calibration scheme that combines thermal equilibration of a working standard gas with a direct mole fraction‐based approach. Results: The method is validated for a large range of isotopic composition values by comparison with other established methods (laser spectroscopy using conventional isotopic scale and isotope ratio mass spectrometry). Direct intercomparison with recently developed ultrahigh‐resolution mass spectrometry shows clearly the advantages of the new laser technique, especially with respect to site specificity of isotopic substitution in the N2O molecule. Conclusions: Our study represents a new methodological basis for the measurements of both singly substituted and clumped N2O isotopes. It has a high potential to stimulate future research in the N2O community by establishing a new class of reservoir‐insensitive tracers and molecular‐scale insights. Karayigit, A.I., Bircan, C., Oskay, R.G., Türkmen, ?., Querol, X., 2020. The geology, mineralogy, petrography, and geochemistry of the Miocene Dursunbey coal within fluvio-lacustrine deposits, Bal?kesir (Western Turkey). International Journal of Coal Geology 228, 103548. Dursunbey coalfield, a typical example of coalfields in the western Anatolia, hosts a mineable coal seam (about 9.0-m coal thickness) with altered tuff layers within early Miocene fluvio-lacustrine sequences. The aim of this study is to identify peat-accumulation conditions and factors controlling the mineralogy and geochemistry of this seam. The standard coal features and petrographical, mineralogical, and elemental compositions display changes throughout the seam. Ash yields display decreasing trends towards to the upper parts of seam, while total C contents and gross calorific values are increasing. Furthermore, the coal-facies patterns evidence changes of depositional conditions and vegetation in the palaeomires. During initial stages of peat accumulation, the contribution of herbaceous peat-forming plants were more common and palaeomires were open to detrital inputs, whereas woody peat-forming were becoming predominant, and the water table was stable and high, which caused development of anoxic conditions, during late stages. Therefore, the content of detrital minerals, such as quartz and clay minerals (illite, smectite, and chlorite) increases in the lower parts of seam, while that of pyrite increases in the upper parts. In addition, the SEM-EDX data show that matrices of clay mineral aggregates are illitic in composition in the lower parts of seam, while those of smectite prevalence are more common below and above altered tuff layers. Interestingly, authigenic rhomboid K-feldspar grains are observed within smectite clay aggregates in the samples from the upper parts of seam. Framboidal pyrite grains and clusters were also commonly identified from these samples as well. This data shows that synchronous volcanic inputs were altered within a hydrologically closed system under slight acidic to neutral conditions during late syngenetic stages.The enriched elements, such as Cr, Ni, Cs, and V, display moderate to strong positive correlations with ash yields while Al2O3, and K2O indicate an aluminosilicate affinity (clay mineral and feldspar). Considering the presence of metamorphic and ophiolitic rocks in the basement and the adjacent areas, clastic inputs into the palaeomire seems to be controlling aluminosilicate-affiliated elements. Additionally, the SEM-EDX analyses denoted that Ni and As are associated with pyrite. The Ni and As-bearing epigenetic pyrite infillings are mostly identified in coal samples below altered tuff layers; hence, As and Ni enrichments are controlled by precipitation of leached pore waters from altered tuff layers. Nevertheless, As- and Ni-bearing syngenetic pyrite grains and clusters are related with the development of anoxic conditions within palaeomires. This could also favour a Mo and U enrichment, which is another testimony for synchronous volcanic inputs altered under anoxic conditions. Overall, high detrital-input ratios from adjacent areas during initial stages of peat-accumulation in the study area controlled by enrichments of aluminosilicate affiliated elements, whereas during late stages of peat-accumulation, the development of a hydrologically closed system and redox conditions within the palaeomire caused As, Ni, Mo, and U enrichments and the formation of smectite and authigenic K-feldspars.Karimpouli, S., Tahmasebi, P., Ramandi, H.L., 2020. A review of experimental and numerical modeling of digital coalbed methane: Imaging, segmentation, fracture modeling and permeability prediction. International Journal of Coal Geology 228, 103552. methane (CBM) is a form of natural gas that is extracted from coalbeds. Characterization of CBMs is very challenging mostly due to the very complex fracture system leading to ambiguous fluid and petrophysical properties. Among several important factors that control the performance of CBMs, permeability is the most crucial one, which summarizes the global fracture system, intensity, connectivity, and production ratio. As such, accurate characterization of CBMs is coupled with fracture delineation and permeability description, which resulted in the development of a wide range of methods. In this paper, all the necessary steps from imaging, segmentation, and modeling of the fractures to various methods of permeability evaluation are reviewed. This paper presents a critical review of all of the existing relevant and significant techniques and compares their performances with special reference to permeability prediction. Several practical and simplified computational methods for calculating permeability are thus reviewed and compared. Finally, this review paper summarizes the current challenges and possible future research.Karnati, V.R., Munaga, T., Gonavaram, K.K., Amitava, B., 2020. Study on strength and leaching behavior of biogeochemical cemented sand. Geomicrobiology Journal 37, 670-681. ground improvement techniques involve densification of soil either by mechanical compaction or chemical grouting while others involve inclusion of reinforcements, etc. Many conventional grout materials were found posing a threat to environment due to their toxic nature and release of greenhouse gases. In this regard, research is initiated in developing more environmentally sustainable additives for soil improvement in which biological based alternatives are gaining momentum. In the present study, a noble technique Microbial Induced Calcite Precipitation (MICP) using Sporosarcina pasteurii was adopted to modify the properties of sand and improve its efficiency by supplementing with Cellulomonas flavigena. The mineralogy of treated specimens was studied using X-Ray Diffraction and Scanning Electron Microscope analyses. The leachability of precipitated calcite was studied under constant flowing conditions and the material was found to be stable. The Unconfined Compressive Strength (UCS) and elastic modulii of the treated specimens were found to be in the range of 266–343?kPa and 14–35?MPa respectively. The angle of internal friction found from Direct Shear Test on treated specimens was observed to be a little lower compared to virgin specimens. The permeability of treated specimen showed a reduction in magnitude by one order approximately.Karygianni, L., Ren, Z., Koo, H., Thurnheer, T., 2020. Biofilm matrixome: Extracellular components in structured microbial communities. Trends in Microbiology 28, 668-681. consist of microbial communities embedded in a 3D extracellular matrix. The matrix is composed of a complex array of extracellular polymeric substances (EPS) that contribute to the unique attributes of biofilm lifestyle and virulence. This ensemble of chemically and functionally diverse biomolecules is termed the ‘matrixome’. The composition and mechanisms of EPS matrix formation, and its role in biofilm biology, function, and microenvironment are being revealed. This perspective article highlights recent advances about the multifaceted role of the ‘matrixome’ in the development, physical–chemical properties, and virulence of biofilms. We emphasize that targeting biofilm-specific conditions such as the matrixome could lead to precise and effective antibiofilm approaches. We also discuss the limited knowledge in the context of polymicrobial biofilms, and the need for more in-depth analyses of the EPS matrix in mixed communities that are associated with many human infectious diseases.Kasuga, I., Suzuki, M., Kurisu, F., Furumai, H., 2020. Molecular-level characterization of biodegradable organic matter causing microbial regrowth in drinking water by non-target screening using Orbitrap mass spectrometry. Water Research 184, 116130. BOM composition in drinking water was explored using Orbitrap MS for non-target screening. Among complex DOM, BOM candidates were screened from the ozonated water and finished drinking water. ● Fourteen BOM candidates, mainly composed of CHO-type formulas, were screened from the ozonated water. Their peak intensities during the treatment process increased after ozonation but decreased after BAC filtration.● Twenty-two BOM candidates, mainly composed of nitrogen-bearing formulas, were screened from the finished water. They were completely different from those found in the ozonated water. Their peak intensities increased after chlorine disinfection, suggesting that chlorine disinfection was involved in their generation.● A chlorine disinfection experiment demonstrated that some components were generated as byproducts, which contained the BOM candidates detected in the finished water. Although BAC filtration can remove BOM produced by ozonation, chlorine disinfection, which is a key factor in controlling waterborne pathogens and suppressing microbial regrowth, is the major generation mechanism of the residual BOM in drinking water.Katsman, R., Dickens, G., 2020. Gas in Marine Sediments (GIMS): past, current, and future (contributions from GIMS-14). Geo-Marine Letters 40, 403-406.: Shallow sediment (<?1000 m below the seafloor) along modern continental margins hosts enormous quantities of low molecular weight hydrocarbons (mostly methane, CH4) that exist as free (gas) bubbles, clathrates (or gas hydrates), or dissolved in water. The total amount and correct distribution of these hydrocarbons at present-day remain wildly unconstrained, principally because of current complications regarding means to detect, to quantify, and to explain. This problem only magnifies over geologic time, which necessarily forces consideration of past variations in sea level, ocean temperature, and carbon fluxes to and from the seafloor. In any case, gas in marine sediments has become an increasingly fascinating topic across a broad spectrum of geo- and bio-sciences.The Gas in Marine Sediments (GIMS) conference series (Table 1), initiated in 1990 by the Shallow Gas Group, was intended to stimulate an awareness of shallow gas and gas-related features (e.g., seepages and pockmarks) within the wider community. GIMS meetings, held approximately every 2 years (Table 1), provide an opportunity for scientists and engineers spanning multiple disciplines to share cutting-edge knowledge in a welcoming environment. During early conferences, there was a concerted effort to foster east-west relationships by encouraging the participation of colleagues from the Eastern Bloc. This goal of facilitating interdisciplinary and international cooperation, as well as publishing key and diverse work continues. Here, we introduce the fourteenth conference (GIMS-14), held in Haifa, Israel (October 14–20, 2018), which led to some interesting papers and key ideas. A Web site for the meeting, including the program and other details, can be found at trips have been an important tradition of GIMS meetings, both to gain camaraderie amongst colleagues and to examine the science of mutual interest. The conference included city tours of Haifa and Jerusalem. More relevant to science, a 1-day field trip, including a cruise, focused on Lake Kinneret (Sea of Galilee), the lowest freshwater lake on Earth at ~?215 m below sea level (Fig. 2). This water body lies in one of the pull-apart basins of the Dead Sea Transform fault system, and because of climate and hydrography, sediments contain abundant gas (mostly CH4). Field-trip participants saw a hands-on demonstration of methane emission from gassy sediments when weighted lines were sunk into sediment and bubbles emerged.Special issue overview: This special issue of Geo-Marine Letters includes 10 contributions highlighting the diversity of topics presented at GIMS-14. The first group of papers focuses on gas emissions from the seafloor. The distribution of hydrocarbon gasses is examined from the Tatar Strait of the northern Sea of Japan (Yatsuk et al. 2020), indicating a large-scale degassing zone that coincides with a variety of free gas indicators. R?mer et al. (2020) examine gas bubble emissions from the Black Sea and show how almost all free gas flares are limited to below depths of 100-m depth. They suggest that these gasses dissolve into the water column at these depths and contribute significantly toward the Black Sea’s anoxic character. Chen et al. (2020) describe high-resolution bathymetry of the seafloor of southwestern Taiwan, and a new type of pockmark, comet-shaped depressions, forming from discrete degassing events associated with large earthquakes. Baranov et al. (2020) examine cold methane seeps from the shelf of the Laptev Sea and report on the shallow water seep fauna of the Siberian Arctic for the first time. Faults determine seep sites, where the community structures are related to extreme oligotrophic conditions local to the area.The second collection of papers addresses methane-derived authigenic mineralization. Judd et al. (2020) examine methane-derived authigenic carbonates (MDAC) from the UK sector of the Irish Sea. Their results suggest the continual formation of MDACs since the last glacial maximum and that methane release to the atmosphere occurred immediately after the local ice sheet retreat. The foraminiferal record of stable isotopes as related to gas hydrate flows is tackled by Dessandier et al. (2020), who investigate the potential biases of these records due to ontogenetic effects. The controls of greigite preservation are examined using rock-magnetic and transmission electron microscope analyses from cores of the Krishna-Godavari basin of India by Badesab et al. (2020a). They suggested that silica diagenesis and silicate weathering, triggered by paleo-methane seepage, played a key role in crystallizing diagenetically formed iron sulfide (greigite) into a silicate matrix, thus enhancing preservation potential. Badesab et al. (2020b) further examine the rock magnetic variations of a long core from the same basin. Results suggest that magnetic iron-bearing sulfide intervals, found below a sulfate-methane transition zone, were controlled by microbially mediated diagenesis, related to fossil gas hydrate zones. Downcore variations in rock magnetic variations appear to be controlled by differential loading of detrital magnetic minerals, in addition to hydrate-induced iron sulfide formation during late diagenesis.The third set of papers discusses shallow gas accumulation in lacustrine sediments. The shallow sediments of Lake Kinneret (Fig. 2) are examined by Liu et al. (2020) who describe the spatial and temporal controls on ebullition using core, chemical, and geophysical techniques. They demonstrate the absence of free gas in sediments of the littoral zone of the lake, where gas content increased toward the profundal zone. They report, for the first time, on the significant role that CH4 production plays in the long-term ebullition pattern, whereas a short-term variability in ebullition was associated with seasonal lake-level changes. In tandem, Uzhansky et al. (2020) studied the temporal (multiannual) changes to sedimentary free gas content in the same lake system, induced by the lake-level change over the studied period and attributed to changes in CH4 solubility. In addition, the spatial variability in gas content indicated higher values in deeper locations of the profundal zone and in the shallow zone proximal to the Jordan River inflow (Fig. 2).Conference thoughts and future considerations: Since the first GIMS conference, which mostly focused on shallow gas in sediment on continental shelves, topics have progressively broadened in scope and significance. This evolution has occurred in part by the inclusion of gas hydrates and emissions from regions containing these compounds. GIMS-14 very much followed this avenue. Of overlapping interest are shallow gas hydrates in the Arctic. They can also relate to other “shallow gas” features in this region, including pockmarks and seafloor venting.Indeed, gas in shallow marine sediment ultimately relates to global carbon cycling, an idea discussed amongst participants at GIMS-14. Methane generally forms from burial and decomposition of solid organic carbon. In many places, through advection and diffusion, this CH4 returns to the ocean through seafloor venting, where much is subsequently oxidized to CO2 or consumed by anerobic oxidation of CH4 and production of HCO3?.The fate of CH4 emissions from shallow sediment extended in several directions at GIMS-14. It included potential changes in CH4 fluxes caused by deglaciation, natural or anthropogenic, as well as implications. This subject was discussed within the context of historical data and modern evidence.Another important subject covered by the conference, the one not addressed sufficiently in the literature, is CH4 ebullition from the freshwater (non-marine) systems (lakes, rivers, and reservoirs). These may present a substantial source of atmospheric CH4. It is obvious that those interested in sedimentary gas should expand their horizons to lakes.Finally, one topic that we universally agreed upon is the poor but common usage of “biogenic gas,” a blanket term that ignores the specific origins of the phenomenon. We, as representatives of the delegates from GIMS-14, propose the use of the term “microbial gas” for CH4 produced in shallow sediment through microbial activity.Many discussions and debates transpired across talks, open sessions, meals, and field trips during GIMS-14. Importantly, the core aspects and special nature of GIMS remain wonderfully intact. These meetings persist as a place for colleagues to meet, to share, and to discuss a common interest in an open and welcoming environment, one particularly good for communication between senior and junior scientists and engineers. Barring any unusual global turmoil, GIMS-15 will take place in Cadiz, Spain during October 2020 (). Cadiz again was selected for intriguing reasons, and the meeting should follow tradition—a relatively small group of participants sharing a wide range of results and ideas in an engaging atmosphere.ReferencesBadesab F, Gaikwad V, Dewangan P (2020a) Controls on greigite preservation in a gas hydrate system of the Krishna-Godavari basin, Bay of Bengal. Geo-Mar Lett. Badesab F, Dewangan P, Gaikwad V, Sebastian JG, Venkateshwarlu M (2020b) A rock magnetic perspective of gas hydrate occurrences in a high-energy depositional system in the Krishna-Godavari basin, Bay of Bengal. Geo-Mar Lett. Baranov B, Galkin S, Vedenin A, Dozorova K, Gebruk A, Flint M (2020) Methane seeps on the outer shelf of the Laptev Sea: characteristic features, structural control, and benthic fauna. Geo-Marine Letters. Chen T-T, Paull CK, Liu C-S, Klaucke I, Hsu H-H, Su C-C, Gwiazda R, Caress DW (2020) Discovery of numerous pingos and comet-shaped depressions offshore southwestern Taiwan. Geo-Marine Letters. Dessandier P-A, Borrelli C, Yao H, Sauer S, Hong W-L, Panieri G (2020) Foraminiferal δ18O reveals gas hydrate dissociation in Arctic and North Atlantic Ocean sediments. Geo-Marine Letters. Judd A, Noble-James T, Golding N, Eggett A, Diesing M, Clare D, Silburn B, Duncan G, Field L, Milodowski A (2020) The Croker Carbonate Slabs: extensive methane-derived authigenic carbonate in the Irish Sea—nature, origin, longevity and environmental significance. Geo-Marine Letters. Liu L, Sotiri K, Dück Y, Hilgert S, Ostrovsky I, Uzhansky E, Katsman R, Katsnelson B, Bookman R, Wilkinson J, Lorke A (2020) The control of sediment gas accumulation on spatial distribution of ebullition in Lake Kinneret. Geo-Marine Letters. R?mer M, Sahling H, Ferreira CS, Bohrmann G (2020) Methane gas emissions of the Black Sea—mapping fromthe Crimean continental margin to the Kerch Peninsula slope. Geo-Marine Letters. Sukenik A, Zohary T, Markel D (2014) The monitoring program. In: Zohary T, Sukenik A, Berman T, Nishri A (eds) Lake Kinneret: Ecology and Management, Aquatic Ecology Series 6. Springer, pp 561–576. Uzhansky E, Katsnelson B, Lunkov A, Ostrovsky I (2020) Spatial and temporal variability of free gas content in shallow sediments: Lake Kinneret as a case study. Geo-Marine Letters. Yatsuk A, Shakirov R, Gresov A, Obzhirov A (2020) Hydrocarbon gases in seafloor sediments of the TATAR strait, the northern sea of Japan. Geo-Marine Letters. , S., Matsui, Y., Früh-Green, G.L., 2020. Radiocarbon content of carbon dioxide and methane in hydrothermal fluids of Okinawa Trough vents Geochemical Journal 54, 129-138. we quantify radiocarbon (14C) content in CO2 and CH4 from hydrothermal fluids collected at 5 vent sites in the Okinawa Trough. These data provide preliminary insights on how different carbon sources and circulation processes contribute to vent fluids and take into consideration all potential contaminations during sample processing and analysis with accelerator mass spectrometer. For CO2, 14C-dead values observed in fluids of most sites (Hatoma, Hitoshi, Noho) demonstrate the complete removal of the inorganic carbon in the recharged seawater. Conversely, the significantly positive 14CO2 are detected in fluids from the Daiyon-Yonaguni site, which implies the persistence of the recharged seawater-derived inorganic carbon and/or a contribution from thermal degradation of sedimentary 14C-containing carbon during fluid upwelling. The CH4 in these fluids were predominantly 14C-dead or nearly 14C-dead, suggesting a source of deep-buried, 14C-dead sedimentary carbon. The methods outlined in our study exemplify a useful way of elucidating radiocarbon contents of geofluids, and provide future studies with a means to improve our understanding of carbon circulation between hydrosphere and lithosphere. Kelemen, P.B., McQueen, N., Wilcox, J., Renforth, P., Dipple, G., Vankeuren, A.P., 2020. Engineered carbon mineralization in ultramafic rocks for CO2 removal from air: Review and new insights. Chemical Geology 550, 119628. Dioxide removal from air (CDR) combined with permanent solid storage can be accomplished via carbon mineralization in ultramafic rocks in at least four ways:1. Surficial CDR: CO2-bearing air and surface waters are reacted with crushed and or ground mine tailings, alkaline industrial wastes, or sedimentary formations rich in reactive rock fragments, all with a high proportion of reactive surface area. This can be implemented at a low cost, but most proposed methods have a very large area footprint at the gigatonne scale. The area requirement can be greatly reduced by calcining (heating to produce pure CO2 for permanent storage or use) followed by recycling of MgO, CaO, Na2O, … Such looping methods have predicted costs that are as low or lower than for direct air capture with synthetic sorbents or solvents (DACSS), and a similar area footprint.2. In situ CDR: CO2-bearing surface waters are circulated through rock formations at depth. These methods potentially have a cost similar to that of surficial carbon mineralization, and a giant storage capacity with reduced surface area requirements, but they involve uncertain feedbacks between permeability, reactive surface area, and reaction rate, providing a fascinating topic for fundamental research. Furthermore, the size, injectivity, permeability, geomechanics, and microstructure of key subsurface reservoirs for in situ CDR remain almost entirely unexplored.3&4. Combined partial enrichment of CO2 using direct air capture with synthetic sorbents (DACSS) plus surficial carbon mineralization (3) or in situ carbon mineralization (4). Energy requirements and total costs for partial enrichment of CO2 are substantially lower than for enrichment to high purity. CO2 enriched air can be sparged through mine tailings at the surface, and/or through water to increase dissolved carbon concentrations prior to circulation through rock reactants. Such combined or hybrid approaches have not been investigated thoroughly, and offer many avenues for optimization.Keshavarz, M.H., Maghsoodi, N.K., Shokrollahi, A., 2020. A reliable model for assessment of melting points of cyclic hydrocarbons containing complex molecular structures, isomers and stereoisomers. Fluid Phase Equilibria 521, 112692. hydrocarbons with desirable melting points are attractive candidates as liquid fuels such as jet fuels due to the presence of high strain energy in some derivatives but available predictive methods may give large deviations for their melting points. A simple model is introduced for reliable prediction of melting points of cyclic hydrocarbons with complex molecular structures, isomers and stereoisomers that include cyclic alkane, alkene and/or alkyne, cage molecules, bridged cyclic and multicyclic hydrocarbon structures. It is based on the number of carbon atoms and two correction terms that correspond to increasing and decreasing values of the melting point resulting from specific structural parameters. Experimental data of melting points for 297 cyclic hydrocarbons were collected from different sources where data of 136 and 161 molecules are used as training and test sets, respectively. The calculated outputs of both training and test sets for the new model are compared with one of the best predictive methods. The values of average absolute deviation (AAD) of the training set for the new and comparative models are 21.0 and 52.1?K, respectively. Meanwhile, the values of AAD of the test set for these models are also 23.8 and 40.6?K, respectively. Further statistical parameters also confirm the higher reliability of the new model.Ketzer, M., Praeg, D., Rodrigues, L.F., Augustin, A., Pivel, M.A.G., Rahmati-Abkenar, M., Miller, D.J., Viana, A.R., Cupertino, J.A., 2020. Gas hydrate dissociation linked to contemporary ocean warming in the southern hemisphere. Nature Communications 11, 3788. warming related to climate change has been proposed to cause the dissociation of gas hydrate deposits and methane leakage on the seafloor. This process occurs in places where the edge of the gas hydrate stability zone in sediments meets the overlying warmer oceans in upper slope settings. Here we present new evidence based on the analysis of a large multi-disciplinary and multi-scale dataset from such a location in the western South Atlantic, which records massive gas release to the ocean. The results provide a unique opportunity to examine ocean-hydrate interactions over millennial and decadal scales, and the first evidence from the southern hemisphere for the effects of contemporary ocean warming on gas hydrate stability. Widespread hydrate dissociation results in a highly focused advective methane flux that is not fully accessible to anaerobic oxidation, challenging the assumption that it is mostly consumed by sulfate reduction before reaching the seafloor.Keuper, F., Wild, B., Kummu, M., Beer, C., Blume-Werry, G., Fontaine, S., Gavazov, K., Gentsch, N., Guggenberger, G., Hugelius, G., Jalava, M., Koven, C., Krab, E.J., Kuhry, P., Monteux, S., Richter, A., Shahzad, T., Weedon, J.T., Dorrepaal, E., 2020. Carbon loss from northern circumpolar permafrost soils amplified by rhizosphere priming. Nature Geoscience 13, 560-565. global temperatures continue to rise, a key uncertainty of climate projections is the microbial decomposition of vast organic carbon stocks in thawing permafrost soils. Decomposition rates can accelerate up to fourfold in the presence of plant roots, and this mechanism—termed the rhizosphere priming effect—may be especially relevant to thawing permafrost soils as rising temperatures also stimulate plant productivity in the Arctic. However, priming is currently not explicitly included in any model projections of future carbon losses from the permafrost area. Here, we combine high-resolution spatial and depth-resolved datasets of key plant and permafrost properties with empirical relationships of priming effects from living plants on microbial respiration. We show that rhizosphere priming amplifies overall soil respiration in permafrost-affected ecosystems by ~12%, which translates to a priming-induced absolute loss of ~40?Pg soil carbon from the northern permafrost area by 2100. Our findings highlight the need to include fine-scale ecological interactions in order to accurately predict large-scale greenhouse gas emissions, and suggest even tighter restrictions on the estimated 200?Pg anthropogenic carbon emission budget to keep global warming below 1.5?°C.Khan, M., Raza, A., Zahoor, M.K., Gholami, R., 2020. Feasibility of miscible CO2 flooding in hydrocarbon reservoirs with different crude oil compositions. Journal of Petroleum Exploration and Production Technology 10, 2575-2585. CO2-based enhanced oil recovery (CO2-EOR) flooding has been used, on many occasions, to maximize the recovery by mobilizing the residual oil. The success of this method, however, depends highly on the minimum miscibility pressure (MMP), the compatibility of CO2 with the reservoir rock and fluids. Although there have been several studies on the application of CO2-EOR, the impact of oil compositions associated with MMP on the feasibility of this technique has not been addressed elsewhere. In this study, a simulation study was carried out to investigate the effect of three different oil compositions on the miscibility and ultimate oil recovery of miscible CO2-EOR method. The results obtained indicated the oil type does not pose a significant impact on the success of miscible CO2-EOR. It was also found that the ultimate recovery of oil increases in a short period of time by injecting CO2 at the miscible conditions at the early stage of natural production. Comparatively, the reservoir with the fluid sample S2 seems to be a suitable choice for the miscible CO2 flooding once the recovery factor was considered together with the total amount of the fluid injected and produced.Kharbush, J.J., Close, H.G., Van Mooy, B.A.S., Arnosti, C., Smittenberg, R.H., Le Moigne, F.A.C., Mollenhauer, G., Scholz-B?ttcher, B., Obreht, I., Koch, B.P., Becker, K.W., Iversen, M.H., Mohr, W., 2020. Particulate organic carbon deconstructed: Molecular and chemical composition of particulate organic carbon in the ocean. Frontiers in Marine Science 7, 518. doi: 10.3389/fmars.2020.00518. dynamics of the particulate organic carbon (POC) pool in the ocean are central to the marine carbon cycle. POC is the link between surface primary production, the deep ocean, and sediments. The rate at which POC is degraded in the dark ocean can impact atmospheric CO2 concentration. Therefore, a central focus of marine organic geochemistry studies is to improve our understanding of POC distribution, composition, and cycling. The last few decades have seen improvements in analytical techniques that have greatly expanded what we can measure, both in terms of organic compound structural diversity and isotopic composition, and complementary molecular omics studies. Here we provide a brief overview of the autochthonous, allochthonous, and anthropogenic components comprising POC in the ocean. In addition, we highlight key needs for future research that will enable us to more effectively connect diverse data sources and link the identity and structural diversity of POC to its sources and transformation processes.Khatun, M., Singh, S., Chakravarti, R., Venkatesh, A.S., 2020. Genetic constraints and possible mechanism of gold mineralization within the carbonaceous metasedimentary units of the Dalma volcano-sedimentary belt, North Singhbhum Mobile Belt, eastern India: Implications from pyrite geochemistry and carbon and sulfur isotope studies. Geological Journal 55, 5233-5250. the present work, gold‐bearing carbonaceous phyllites in the Dalma volcano‐sedimentary belt (DVSB), occupying the central region of the North Singhbhum Mobile Belt in eastern India were studied to understand the nature and mode of occurrence of gold mineralization. We propose that the protolith of the carbonaceous phyllites, that is, organic‐rich black shale, was the major source of Au in the phyllite‐hosted gold mineralization reported from the DVSB. LA‐ICP‐MS analysis of pyrite in this study reveals elevated Au contents in the early‐formed sedimentary pyrite (syngenetic and diagenetic pyrite). Trace element systematics confirms the presence of invisible Au with in the sedimentary pyrite as solid solution (invisible gold). Petrographical evidences suggest a close spatial relationship of Au‐enriched pyrite and carbonaceous material. Stable carbon isotope values confirm the organic nature of the carbonaceous matter. Further, the high organic carbon content of these samples falls well within the favourable range of an auriferous carbonaceous host rock. These evidences suggest that the organic carbon played a key role in fixation of gold in the carbonaceous shales. Subsequent diagenesis resulted in the release of Au from the organic matter and its incorporation onto the coeval sedimentary pyrite. Field observations and reports by previous workers indicate that these rocks were subjected to a late‐stage metamorphic/hydrothermal event. Paragenesis of pyrite coupled with its trace element systematics reveals that this late‐stage event resulted in the formation of younger euhedral pyrite and pyrrhotite and released invisible gold from the pre‐existing sedimentary pyrite followed by its precipitation in the quartz reefs. Based on these studies, we propose a two‐stage model of gold mineralization, wherein gold was initially incorporated in black shale‐hosted sedimentary pyrite and later released and precipitated in quartz veins.Khaustov, A., Redina, M., 2020. Fractioning of the polycyclic aromatic hydrocarbons in the components of the non-equilibrium geochemical systems (thermodynamic analysis). Applied Geochemistry 120, 104684. paper investigates the properties of geochemical systems components (GCS) within the thermodynamic framework. In a departure from previous approaches, the maximum possible number of interconnected media in holistic GCS is analyzed using hierarchical classification procedures.The studied sample covers the maximum possible selection of media, which are interconnected in natural systems in real conditions.The paper reports that complex organic compounds, such as polycyclic aromatic hydrocarbons (PAHs) are highly informative indicators of the properties of substances migration in media. Being geochemical markers, these compounds demonstrate the ability to accumulate on geochemical barriers and selectively move in interacting media, which makes them key objects of study. In addition, the marker role of these compounds draws on their “confinement” to several geochemical processes (natural or industrial) and ability to ultimately identify the source of the pollution. The existing accounts fail to describe these mechanisms of mass transfer. The proposed phenomenological models of migration, transformation, and accumulation of PAHs are based on quantitative estimates, which provide more consistent results compared with the descriptive representations of the behavior of substances. This allowed us to identify the role of studied physicochemical characteristics of PAHs in their accumulation in the environmental media. The paper demonstrates that the most active evolution of GCS occurs in case plant media and, in general, living matter is included in their composition.Kim, M., Shin, H., 2020. Numerical simulation of undulating shale breaking with steam-assisted gravity drainage (UB-SAGD) for the oil sands reservoir with a shale barrier. Journal of Petroleum Science and Engineering 195, 107604. thick oil sands reservoir separated into two thin oil sands reservoirs by a shale barrier, particularly when the separated reservoir thickness is less than 10?m, is inefficient for economic steam-assisted gravity drainage (SAGD) applications. This paper proposes undulating shale breaking with SAGD (UB-SAGD) to develop this type of reservoir, and the trajectory of undulating drilling to break the shale was designed. In addition, sensitivity analysis was performed to evaluate the effects of the area and permeability of a breaking zone and steam injection pressure. The UB-SAGD is a novel in-situ recovery method that applies undulating drilling to break the shale in the parallel direction and the above SAGD well pairs. In addition, it adds an extra injector to facilitate thermal communication between the upper and lower parts of the shale barrier, and the steam chamber can be expanded into the upper the oil sands layer along a flow path. As the area and permeability of the breaking zone were increased, the recovery factor (RF) and maximum NPV (M_NPV) increased, and the cumulative steam-oil ratio (CSOR) decreased. A comparison of the low and high steam injection pressures revealed the M_NPV of high steam injection pressure to be higher than that of low steam injection pressure because a high injection pressure facilitates flow in a smaller area of the breaking zone. The RF and CSOR of best result were improved by 24.65% and 10.21%, respectively, compared to two well-pairs of SAGD without undulating drilling. In addition, the M_NPV of this result was $3.05?MM higher than that of two well-pairs. The UB-SAGD will be very useful for the economic development of shale interbedded oil sands reservoirs using conventional SAGD.Kim, T., Palmore, G.T.R., 2020. A scalable method for preparing Cu electrocatalysts that convert CO2 into C2+ products. Nature Communications 11, 3622. of efficient catalysts for selective electroreduction of CO2 to high-value products is essential for the deployment of carbon utilization technologies. Here we present a scalable method for preparing Cu electrocatalysts that favor CO2 conversion to C2+ products with faradaic efficiencies up to 72%. Grazing-incidence X-ray diffraction data confirms that anodic halogenation of electropolished Cu foils in aqueous solutions of KCl, KBr, or KI creates surfaces of CuCl, CuBr, or CuI, respectively. Scanning electron microscopy and energy dispersive X-ray spectroscopy studies show that significant changes to the morphology of Cu occur during anodic halogenation and subsequent oxide-formation and reduction, resulting in catalysts with a high density of defect sites but relatively low roughness. This work shows that efficient conversion of CO2 to C2+ products requires a Cu catalyst with a high density of defect sites that promote adsorption of carbon intermediates and C–C coupling reactions while minimizing roughness.Klimas, A., Zhao, Y., 2020. Expansion microscopy: Toward nanoscale imaging of a diverse range of biomolecules. ACS Nano 14, 7689-7695. microscopy (ExM) has become a powerful imaging tool for visualizing the nanoscale organization of protein and nucleic acid targets in cells and tissues using only a conventional microscope. Until recently, current ExM approaches have had limited applicability to imaging other biomolecules, such as lipids and small molecules. With the new TRITON probes reported by Wen et al. in this issue of ACS Nano, ExM can now be used to perform nanoscale imaging of the cytoskeleton and lipid membranes. In this Perspective, we offer a brief overview of recent developments in ExM, with a focus on biomolecule anchoring and labeling strategies that target a wide range of biomolecules to the water-swellable polymer formed in situ, a key step that ensures biomolecules or labels of interest are separated in space and can be resolved on a conventional microscope. In addition to these new advancements, we discuss challenges and future directions in this exciting field.Kokh, M.A., Assayag, N., Mounic, S., Cartigny, P., Gurenko, A., Pokrovski, G.S., 2020. Multiple sulfur isotope fractionation in hydrothermal systems in the presence of radical ions and molecular sulfur. Geochimica et Cosmochimica Acta 285, 100-128. study is aimed to evaluate the role played by the sulfur radical ions (S3.? and S2.?) and molecular sulfur (S0) on sulfur isotope fractionation and to investigate if these species may leave an isotope fingerprint in hydrothermal systems. For this purpose, we combined (i) experiments using a hydrothermal reactor with aqueous S3.?(S2.?)-S0-sulfate-sulfide fluids and pyrite across a wide range of temperatures (300–450?°C), pressures (300–800?bars), fluid acidity (4?<?pH?<?8) and with elevated total sulfur concentrations (0.1–1.0?mol/kg fluid) favorable for formation of those polymeric sulfur species, (ii) precise quadruple S isotope analyses of the different S-bearing aqueous species in sampled fluids and in-situ precipitated pyrite, and (iii) thermodynamic modeling of sulfur aqueous speciation and solubility. Our results quantitatively confirm both equilibrium and kinetic SO4-H2S and pyrite-H2S mass dependent fractionation (MDF) factors previously established using extensive experimental and natural data from more dilute fluids in which polymeric sulfur species are negligible. MDF signatures of S0 measured in the sampled fluids of this study reveal different S0-forming pathways such as (i) breakdown on cooling of S3.? (and S2.?) and other chain-like S0 polymers only stable at high temperature and being isotopically identical to H2S; (ii) cyclooctasulfur (S80, liquid or solid) precipitating by recombination of sulfate and sulfide and/or by exchange with polysulfide dianions (Sn2?) on cooling and being slightly 34S-enriched compared to H2S (by ～2‰ of δ34S); and iii) a different type of S0 resulting from thiosulfate irreversible breakdown and being highly 34S-depleted (by ～12‰) relative to H2S. Our data do not show any significant mass independent fractionation (MIF) of 33S and 36S, with Δ33S and Δ36S values of any S aqueous species and pyrite being within ±0.1‰ and ±1.0‰, respectively. Therefore, under the investigated experimental conditions, the radical S3.? ion is unlikely to generate significant MIF in the hydrothermal fluid phase and in pyrite and native sulfur precipitated therefrom. Our study supports the existing interpretations of small Δ33S and Δ36S variations between sulfide/sulfate-bearing fluid and pyrite as MDF in terms of reaction kinetics, different reaction pathways, and mass conservation effects such as mixing of S reservoirs or Rayleigh distillation. Our data extend, across a wider range of sulfur concentration and chemical speciation, the existing multiple S isotopes models that exploit such variations as a complement to the traditional δ34S tracer to monitor the approach to equilibrium and evolution of hydrothermal fluids.Kosir, S., Stachler, R., Heyne, J., Hauck, F., 2020. High-performance jet fuel optimization and uncertainty analysis. Fuel 281, 118718. jet fuel represents a subset of sustainable aviation fuel that improves the value and performance of the fuel while reducing greenhouse gas emissions and remaining within ‘drop-in’ operability and safety limits. Here, performance gains via increased specific energy [MJ/kg] and energy density [MJ/L] achievable with high-performance jet fuel have been bound by optimizing blends of molecules considering 10 operability and safety properties. Aleatoric and epistemic uncertainties associated with the optimization have been quantified using Latin hypercube sampling, with the associated variance in performance, composition, and operability properties reported. Two optimization scenarios were considered-one with and one without the 8% minimum aromatic requirement- to determine the effect on fuel performance and composition while exploring the possibility of replacing aromatics with cycloalkanes in jet fuel.The results of this study are average specific energy/energy density increases of 1.61/2.36% and 1.84/2.46% relative to Jet A with and without the aromatic constraint respectively, indicating that aromatics are not desirable for fuel performance. Uncertainty for performance properties was low with 1σ and 2σ values at ±0.2% and ±0.4% of the average Pareto front values for both scenarios, which suggests that this study is a good indicator of the performance benefits that can be conferred via high-performance jet fuel. Compositions were biased heavily toward cycloalkanes at 70% and 81% respectively, with low-temperature viscosity and density serving as the limiting operability constraints. This study concludes that cycloalkanes can replace aromatics in jet fuel considering operability limits while increasing fuel performance and reducing soot emissions.Kosyakov, D.S., Ul’yanovskii, N.V., Latkin, T.B., Pokryshkin, S.A., Berzhonskis, V.R., Polyakova, O.V., Lebedev, A.T., 2020. Peat burning – An important source of pyridines in the earth atmosphere. Environmental Pollution 266, Part 1, 115109. of the chemical composition of atmospheric aerosols, rain water and snow in various regions of the globe quite often show the presence of pyridine and a number of its low mass derivatives. Nevertheless, the sources of those compounds in the environment have not yet been established and definitely require elucidation, supported by reliable experimental results. In the present work the chemical composition of peat combustion products as one of the important sources of atmospheric aerosol emission is studied by two-dimensional gas chromatography – high-resolution mass spectrometry with a focus on the detection of pyridine derivatives. Twenty-five compounds of this class were reliably identified and quantified in laboratory experiments on peat burning. Among them 3-hydroxypyridine predominates, while the rest analytes are mostly represented by alkyl derivatives: pyridine, 2-methylpyridine, 3-methylpyridine, 2,5-dimethylpyridine, 2,6-dimethylpyridine, 2-ethylpyridine, lutidines (in order of decreasing concentration). The distribution of these combustion products coincides with that obtained earlier in environmental studies carried out in Arctic, Central Russia and France. The experiments on peat thermal decomposition by pyrolysis GC-MS demonstrated that the maximum concentrations as well as the number of detected analytes were found under conditions of oxygen lack and a temperature of about 500?°C, i.e. characteristic conditions of peat wildfires. The observed levels of pyridines’ emission recalculated on the peat dry weight exceeded 200?mg?kg?1. Considering hundreds of millions tons of peat burning in megafires over 20,000 tons of pyridines penetrate the Earth atmosphere annually. The obtained results allow concluding that peat burning may be the major and still underestimated source of pyridine and lower alkylpyridines in the Earth atmosphere.Kottuparambil, S., Agusti, S., 2020. Cell-by-cell estimation of PAH sorption and subsequent toxicity in marine phytoplankton. Chemosphere 259, 127487. Aromatic Hydrocarbons (PAHs) have elicited increasing concern due to their ubiquitous occurrence in coastal marine environments and resultant toxicity in organisms. Due to their lipophilic nature, PAHs tend to accumulate in phytoplankton cells and thus subsequently transfer to other compartments of the marine ecosystem. The intrinsic fluorescence properties of PAHs in the ultraviolet (UV)/blue spectral range have recently been exploited to investigate their uptake modes, localization, and aggregation in various biological tissues. Here, we quantitatively evaluate the sorption of two model PAHs (phenanthrene and pyrene) in three marine phytoplankton species (Chaetoceros tenuissimus, Thalassiosira sp. and Proteomonas sp.) using a combined approach of UV excitation flow cytometry and fluorescence microscopy. Over a 48-h exposure to a gradient of PAHs, Thalassiosira sp. showed the highest proportion of PAH-sorbed cells (29% and 97% of total abundance for phenanthrene and pyrene, respectively), which may be attributed to its relatively high total lipid content (33.87 percent dry weight). Moreover, cell-specific pulse amplitude modulation (PAM) microscope fluorometry revealed that PAH sorption significantly reduced the photosynthetic quantum efficiency (Fv/Fm) of individual phytoplankton cells. We describe a rapid and precise hybrid method for the detection of sorption of PAHs on phytoplankton cells. Our results emphasize the ecologically relevant sub-lethal effects of PAHs in phytoplankton at the cellular level, even at concentrations where no growth inhibition was apparent. This work is the first study to address the cell-specific impacts of fluorescent toxicants in a more relevant toxicant-sorbed subpopulation; these cell-specific impacts have to date been unidentified in traditional population-based phytoplankton toxicity assays.Krajcarz, M., Krajcarz, M.T., Baca, M., Baumann, C., Van Neer, W., Popovi?, D., Sudo?-Procyk, M., Wach, B., Wilczyński, J., Wojenka, M., Bocherens, H., 2020. Ancestors of domestic cats in Neolithic Central Europe: Isotopic evidence of a synanthropic diet. Proceedings of the National Academy of Sciences 117, 17710-17719.: Most of today’s domesticates began as farm animals, but cat domestication took a different path. Cats became commensal of humans somewhere in the Fertile Crescent, attracted to early farmers’ settlements by rodent pests. Cat remains from Poland dated to 4,200 to 2,300 y BCE are currently the earliest evidence for the migration of the Near Eastern wildcat to Central Europe. Tracking the possible synanthropic origin of that migration, we used stable isotopes to investigate the paleodiet. We found that the ecological balance was already changed due to the expansion of Neolithic farmlands. We conclude that among the Late Neolithic Near Eastern wildcats from Poland were free-living individuals, who preyed on rodent pests and shared ecological niches with native European wildcats.Abstract: Cat remains from Poland dated to 4,200 to 2,300 y BCE are currently the earliest evidence for the migration of the Near Eastern cat (NE cat), the ancestor of domestic cats, into Central Europe. This early immigration preceded the known establishment of housecat populations in the region by around 3,000 y. One hypothesis assumed that NE cats followed the migration of early farmers as synanthropes. In this study, we analyze the stable isotopes in six samples of Late Neolithic NE cat bones and further 34 of the associated fauna, including the European wildcat. We approximate the diet and trophic ecology of Late Neolithic felids in a broad context of contemporary wild and domestic animals and humans. In addition, we compared the ecology of Late Neolithic NE cats with the earliest domestic cats known from the territory of Poland, dating to the Roman Period. Our results reveal that human agricultural activity during the Late Neolithic had already impacted the isotopic signature of rodents in the ecosystem. These synanthropic pests constituted a significant proportion of the NE cat’s diet. Our interpretation is that Late Neolithic NE cats were opportunistic synanthropes, most probably free-living individuals (i.e., not directly relying on a human food supply). We explore niche partitioning between studied NE cats and the contemporary native European wildcats. We find only minor differences between the isotopic ecology of both these taxa. We conclude that, after the appearance of the NE cat, both felid taxa shared the ecological niches.Krishnamurthy, P., 2020. The Deccan Volcanic Province (DVP), India: A review. Journal of the Geological Society of India 96, 9-35. Deccan Volcanic Province (DVP), covering presently an area of 0.5 million km2, and estimated to be 2–3 times larger during the Upper Cretaceous-Paleocene, is one of the largest continental flood basalt provinces of the world. Its formation has been linked to the foundering of the Gondwanaland and Greater India’s northward drift, passing over the Reunion plume and eruption of over a million km3 of lava that apparently led to a mass extinction of global proportions. The DVP has thus been a major domain of scientific interest and study the world over. It had received attention since the 1830s, first from the army and civil service men of the British Raj and subsequently from the officers of the Geological Survey of India (GSI) founded in 1851, and academicians from a number of Indian Universities and research Institutions, often in collaboration with geologists from countries such as the UK, USA, Russia, France, Japan, Italy and others. Thus, studies of the DVP conducted for over 170 years, and especially in the last five decades, have provided a very large database that has led to a better understanding of the genesis and evolution of the this province and similar flood basalt provinces of the world.The DVP is thickest in the Western Ghats, forming many individual 400 m to 1650 m thick sections over some 700 km. The structural evolution of the lava sequence envisages a pre-uplift, thick (c. 2–3 km), lensoid pile of dense basalt that gradually sank into the crust by the end of the eruptive phase, followed by an uplift of the western margin of the Deccan due to both denudational-isostasy reasons and the associated geomorphological and structural evolution of the lava pile from Tertiary uplift and coastal flexure formation (the Panvel structure). Such an evolution has led to stresses that get accommodated along fractures in the pre-Deccan basement at varying depths and apparently provide the loci for seismicity observed over the province. The DVP is predominantly composed of quartz- and hypersthene-normative tholeiitic basalts in the plateau regions (Western Ghats and adjoining central and eastern parts, Malwa and Mandla). However, along the ENE-WSW-trending Narmada-Tapi rift zones, the N-S to NNW-SSE-trending Western coastal tract, the Cambay rift zone, and the Saurashtra and Kutch regions, the DVP shows considerable diversity in terms of structures, dyke swarms and dyke clusters, and intrusive and extrusive centres with diverse rock types. These include: primary picrite basalts and their differentiates (e.g., Botad, Dhandhuka, Wadhwan Jn., Pavagadh), granophyre-rhyolite intrusive ring-complexes and mixed basalt-rhyolite associations (e.g., Alech, Barda, Osham, Chogat-Chamardi, Mumbai Island, and others), carbonatite-nephelinite associations (Amba Dongar-Kawant), gabbro-anorthosite-nepheline syenite-syenite ring/layered complexes(e.g., Mt. Girnar, Mundwara, Phenai Mata), mantle-derived spinel peridotite-hosting melanephelinites and basanites (e.g. Dhrubya, Vethon and others in Kutch), besides scores of alkaline and lamprophyre dykes. Some of these complexes are associated with high gravity anomalies indicating dense plutonic bodies at depths.Flow morphological studies of the DVP have led to the recognition of two main types of flows, namely ‘a’a (typically forming simple, sheet flows) and p?hoehoe (typically forming compound, pahoehoe lobate flows) with transitions between them that result in mixed types. The ‘a’a types are largely single units found in the peripheral parts where thicknesses of the flow sequence range from a few meters to a few tens of meters. The compound p?hoehoe flows contain many units or lobes and are largely found in the thicker sections of Western Ghats, and also in the central parts of the province. The flow sequences of the Western Ghats (c. 400 m to 1650 m thick and spread over an area of400 km × 100 km along the N-S tract from north of Nasik to Belgaum) have been mapped and correlated using flow morphology, petrology and selected trace elements (Sr, Ba, Zr, Y and Ti) and Sr- isotopes. Such a combination of geochemical characters, constrained further by altitude and magnetic polarity (chrons 30N-29R-29N) have led to the delineation of the flow sequences from north to south into a Deccan Basalt Group, comprising three Subgroups from the base to the top, namely the Kalsubai, Lonavala and Wai Subgroups, with twelve (12) formations in total, each formation containing many flows. Giant plagioclase basalts (GPBs) and bole beds of diverse origin (intertrappean sediments, weathered basalt or tuffs with baking effects) have been found in many flow sequences of the DVP, especially in the Western Ghats and contiguous plateau regions, and these interflow units help in subregional-scale mapping and also provide insights into magma chamber processes and eruptive breaks in the volcanic cycles.Field and geochemical studies of some twenty-three (23) flow sequences (10 from Western Ghats, five from central India and eight from eastern India) by several groups have enabled correlation of some formations of the Western Ghats such as the Ambenali (crustally uncontaminated) and Poladpur (contaminated) over long distances (c. 400–700 km) to Toranmal, Mhow, Chikaldara, Jabalpur and other sections. However, these formations occur at different stratigraphie elevations at these places and also differ in some isotopic characters (e.g. 206Pb/204Pb). Such features have cast doubts on long distance travel of flows from a single source and led to suggestions of multiple source areas (vents and dykes) as also inferred from the two zones of compositional diversity mentioned above.Based on detailed field, petrological and geochemical characters including isotopic data and Ar-Ar ages, dyke swarms and clusters in the Narmada-Tapi and western coastal tracts have been shown to belong to two groups: (1) The randomly oriented group between Pune and Nasik as possible feeders to the lava flow sequences of the Western Ghats and (2) Some of the dykes from the east-west-oriented Narmada-Tapi swarm, attributed to active N-S extension during the flood basalt episode, and showing chemical affinities to the lower and middle formations (Jawhar, Igatpuri, Neral, Thakurwadi, Bhimashankar, Khandala). A wide variety of petrographic types of basalts have been observed in the DVP attesting to the diverse crystallisation and differentiation of the different magma types during transport and in magma chambers. Based on petrographic and mineralogical data from a number of thick sections, it has been inferred that minerals such as olivine (Fo90–Fo20), clinopyroxenes (diopsidic augite, augite, subcalcic augite and pigeonite), plagioclase (An84–An30) and opaque oxides including spinels show considerable variations depending upon the tholeiitic or alkaline character of the host magma and its degree of evolution. Secondary minerals, especially zeolites such as heulandite and stilbite, are found in all the ten formations of the Western Ghats whereas merlionite and analcite are only found in the Khandala Formation. Other ten species are of variable abundance are found in the ten formations of the Western Ghats and other areas. Zeolite zonation in DVP suggested earlier has not been substantiated by recent studies, instead multigeneration of secondary minerals in cavities is attributed to late hydrothermal activity from Paleocene to early Miocene.Krmpoti?, M., Jembrih-Simbürger, D., Siketi?, Z., Markovi?, N., Anghelone, M., Tadi?, T., Plav?i?, D., Malloy, M., Radovi?, I.B., 2020. Identification of synthetic organic pigments (SOPs) used in modern artist’s paints with secondary ion mass spectrometry with Mev ions. Analytical Chemistry 92, 9287-9294. work reports on the first systematic study using secondary ion mass spectrometry with MeV ions (MeV-SIMS) for analysis of synthetic organic pigments (SOPs) that can be usually found in modern and contemporary art paints. In order to prove the applicability of the method to different chemical classes of SOPs, 17 pigments were selected for the analyses. The focus was on blue and green phthalocyanines, yellow and red (naphthol AS) azo pigments, red quinacridone, anthraquinone, and diketopyrrolo-pyrrole pigments. Since there are no reference spectra available for this technique, pure pigment powders were measured first to create a database. Simple two-component paint systems were also prepared for testing purposes by mixing synthetic organic pigments with alkyd and acrylic binders. Commercial paints that contain the SOPs with identical C.I. numbers as in the prepared two-component samples were analyzed. All pigments were successfully identified in commercial products in the MeV-SIMS mass spectra through molecular and larger specific fragment ion peaks in the positive-ion mode. The main advantages of MeV-SIMS over other techniques used in SOPs identification, like pyrolysis gas chromatography mass spectrometry (Py-GC/MS), direct-temperature resolved mass spectrometry (DTMS), and laser desorption ionization mass spectrometry (LDIMS), can be summarized as follows: (i) pigments and binders can be detected simultaneously in the same mass spectrum acquired over a short measurement time (up to 500 s), (ii) only small sample flakes are required for the measurements, which are analyzed without any chemical treatment prior to the analyses, (iii) samples are not consumed during the analyses and can be reused for other measurements, e.g., multielemental analysis by other ion beam analysis (IBA) techniques, such as particle-induced X-ray emission (PIXE). Compared to, e.g., Raman spectroscopy, the significant benefit of MeV-SIMS is the exact identification of the SOPs in the paints even if pigments of similar structures are measured.Kularathna, E.K.C.W., Pitawala, H.M.T.G.A., Senaratne, A., Ratnayake, A.S., 2020. Play distribution and the hydrocarbon potential of the Mannar Basin, Sri Lanka. Journal of Petroleum Exploration and Production Technology 10, 2225-2243. Mannar Basin is a frontier failed rift basin between India and Sri Lanka. The Sri Lankan part has an area exceeding 42,000 km2. Although the recent two gas discoveries have confirmed the existence of an active petroleum system in the Mannar Basin, a major portion of the basin is still poorly explored. This article summarized the progress of current exploration activities and the hydrocarbon potential of the Mannar Basin. This basin began to evolve since the Upper Jurassic and experienced two rifting events; an early Late Jurassic syn-rift phase associated with East–West Gondwana break up; and a later, earliest Cretaceous syn-rift phase associated with Antarctica separation from greater India around 142?Ma. Rifting was followed by a post-rift phase comprising a thermal sag period and an inversion period. Three potential source rocks intervals have been interpreted at Maastrichtian–Campanian, Albian–Aptian, and Late Jurassic stratigraphic levels. The basin modelling work has confirmed that (1) mature potential source rocks (mainly Type II) exist below the Maastrichtian–Campanian strata and (2) the best potential source rocks (mainly Type II) exist at Albian–Aptian stratigraphic levels. The Late Jurassic source rocks have more potential for gas, while other sources have potential for both oil and gas. According to basin modelling results, Maastrichtian–Campanian and Albian–Aptian source rocks reach the oil window in the present-day depocentre around 45?Ma and 80?Ma, respectively. The Late Jurassic source rocks (mainly Type III) reach the gas window around 112?Ma in the present-day depocentre. Five play levels were defined for the whole stratigraphic section of the Mannar Basin. Tertiary play level is dominated by submarine fans, mounds and rollover anticline like structures. The Upper Cretaceous play is dominated by forced-fold structures, intra-basalt turbidite sands, and sub-volcanic sand-rich systems. The Lower Cretaceous play is dominated by reefs and abrupt margin pinch outs. The Upper Jurassic play is dominated by abrupt margin pinch outs. The Basement play consists of weathered basement rocks. The main challenge of the Mannar Basin is imaging below the flood volcanic layer, which inhibits the penetration of seismic energy and results in low-quality seismic data. Therefore, hydrocarbon potential assessments have become a major challenge below the Upper Cretaceous. The interpretation shows that the basin has a low risk for the source and reservoir, and high risk for seal and traps. New exploration activity would unlock more potential areas for hydrocarbon accumulations. Finally, the findings of this study can help for better understanding of hydrocarbon potential areas and current progress of exploration activities in the Mannar Basin, Sri Lanka.Kumagai, S., Matsukami, A., Kabashima, F., Sakurai, M., Kanai, M., Kameda, T., Saito, Y., Yoshioka, T., 2020. Combining pyrolysis–two-dimensional gas chromatography–time-of-flight mass spectrometry with hierarchical cluster analysis for rapid identification of pyrolytic interactions: Case study of co-pyrolysis of PVC and biomass components. Process Safety and Environmental Protection 143, 91-100. of plastic/lignocellulosic biomass mixtures produces an extremely complex assortment of pyrolyzates. In the present work, co-pyrolysis of PVC with cellulose or xylan or milled wood lignin was conducted by employing pyrolysis–two-dimensional gas chromatography–time-of-flight mass spectrometry (Py-GC?×?GC-TOFMS) with the aim of achieving high throughput and comprehensive analysis of the complex pyrolyzates. Then, hierarchical cluster analysis (HCA), which is an algorithm that groups similar objects into groups called clusters, was applied to accomplish rapid screening for compounds influenced by pyrolytic interactions. This combined approach improved compound separation and identifiability and allowed the subsequent easy identification of new compounds and compounds increased or decreased by pyrolytic interactions during co-pyrolysis. The change in distribution during co-pyrolysis clearly suggests the occurrence of HCl-catalyzed dehydration of anhydrosugars and conversion of methoxyphenols into phenolic compounds. Thus, this study reveals the effectiveness of the approach combining Py-GC?×?GC-TOFMS with HCA, which promises to contribute to the acceleration of research on pyrolytic interactions. The understanding of pyrolytic interactions gained thereby will be crucial for maximizing the yield and quality of desired chemicals and fuels from plastic/lignocellulosic biomass.Kumar, R.S., Chaturvedi, K.R., Iglauer, S., Trivedi, J., Sharma, T., 2020. Impact of anionic surfactant on stability, viscoelastic moduli, and oil recovery of silica nanofluid in saline environment. Journal of Petroleum Science and Engineering 195, 107634. nanofluid stability in saline environment has been a long-standing challenge as salt ions screen-out the surface charge of the nanoparticles (NPs), rendering them unstable. This study thus reports the use of an anionic surfactant (sodium dodecylsulfate, SDS), as co-stabilizer, that not only controls the effect of salt, but also dramatically improves nanofluid stability by controlling the agglomeration rate. Silica NPs of 0.5 wt%, SDS with concentration ≥ critical micelles concentration (CMC), and polymer polyacrylamide (PAM) of 1000 ppm were used while the concentration of NaCl was explored up to 5 wt%. The dispersion stability of nanofluid without salt (NaCl) was found to be ~4 weeks which further increased to ~7 weeks with increasing SDS concentration. With increasing SDS (>CMC), a reduction in NP agglomeration was observed that delayed the NP settlement. The effect of salinity was also investigated for flow properties of nanofluids and, an unstable rheological response (transition from viscoelastic to viscous) was observed with increasing NaCl concentration. However, SDS (>CMC) made nanofluid rheologically stable up to saline environment of 3 wt%, an optimum salinity was identified. SDS role on nanofluid stabilization in saline environment is also generalized for enhanced oil recovery (EOR) applications in a porous media enriched with varying salinity. With increasing salinity, the cumulative oil recovery from sand-pack reduced and reached to minimum level of 48% original oil in place (OOIP) at 3 wt% NaCl which was 58% OOIP without salinity. Oil recovery re-established to 55% OOIP in presence of increasing SDS concentration, which is remarkable for nanofluid applicability in saline environment where conventional methods typically show challenges. Even in the presence of 4 wt% NaCl, the synergy between surfactant and nanofluid enabled an improvement in oil recovery and subdued surfactant adsorption in both unconsolidated and consolidated porous media, paving future way for field implementation.Kumar, S., Foroozesh, J., Edlmann, K., Rezk, M.G., Lim, C.Y., 2020. A comprehensive review of value-added CO2 sequestration in subsurface saline aquifers. Journal of Natural Gas Science and Engineering 81, 103437. paper comprehensively reviews CO2 sequestration process in saline aquifers. The storage mechanisms including structural, residual, solubility, and mineral trappings are assessed along with a discussion of their relative contributions, and their key parameters and optimisations. In view of storage security and capacity, effects of rock and fluid properties and reservoir conditions together with injection strategies are discussed. Furthermore, CO2 storage site selection is investigated followed by an evaluation of the different measurement, monitoring and verification methods to mitigate the risk of leakage. Field examples with key learnings are also presented to help engineers with sustainable development of storage projects.Kurzweil, F., Münker, C., Hoffmann, J.E., Tusch, J., Schoenberg, R., 2020. Stable W isotope evidence for redistribution of homogeneous 182W anomalies in SW Greenland. Geochemical Perspectives Letters 14, 53-57. present the first high precision stable tungsten isotope data for a comprehensive Eoarchean rock suite from the Isua region of SW Greenland with the aim to reconstruct the sources and processes that controlled the inventory of W in Eoarchean time and to place constraints on the origin of 182W anomalies in Eoarchean rocks. When compared to modern igneous rocks, the observed range of δ186/184W in the Eoarchean rocks is substantially larger, ranging from ?0.072 to +0.249 ‰. But unlike in modern igneous rocks, we find no co-variation of δ186/184W with other geochemical parameters. Multiple stage mobilisation and re-enrichment of W by metasomatic fluids entirely obscured pristine geochemical signals. However, our results illustrate the potential of applying stable W isotopes as geochemical tracer for alteration effects on primary 182W signatures. Despite secondary alteration and the large variation in δ186/184W the excesses in 182W that were previously observed in the same rock samples appear to be unaffected by alteration arguing that the excesses were most likely initially uniform in the whole Eoarchean assemblage of SW Greenland. Kutcherov, V.G., Dmitrievsky, A.N., Ivanov, K.S., Serovaiskii, A.Y., 2020. The deep hydrocarbon cycle: From subduction to mantle upwelling. Doklady Earth Sciences 492, 338-341. results and geological observations suggesting the existence of a deep hydrocarbon cycle are presented. During immersion hydrocarbons accumulated in the Earth’s crust in the slab generally maintain stability to a depth of 50 km. With deeper immersion, the hydrocarbon fluids contact the surrounding ferrous minerals forming a mixture of iron hydride and iron carbide on the depths of 100–290 km. Iron carbide transported into the asthenosphere by convective flows can act as carbon donors and react with hydrogen donors presented in the asthenosphere and form an aqueous-hydrocarbon fluid. This fluid can migrate through deep faults into the Earth’s crust and form oil and gas deposits.L’Haridon, S., Haroun, H., Corre, E., Roussel, E., Chalopin, M., Pignet, P., Balière, C., la Cono, V., Jebbar, M., Yakimov, M., Toffin, L., 2020. Methanohalophilus profundi sp. nov., a methylotrophic halophilic piezophilic methanogen isolated from a deep hypersaline anoxic basin. Systematic and Applied Microbiology 43, 126107. novel anaerobic methylotrophic halophilic methanogen strain SLHTYROT was isolated from a deep hypersaline anoxic basin called “Tyro” located in the Eastern Mediterranean Sea. Cells of SLHTYROT were motile cocci. The strain SLHTYROT grew between 12 and 37?°C (optimum 30?°C), at pH between 6.5 and 8.2 (optimum pH 7.5) and salinity from 45 to 240?g?L?1 NaCl (optimum 135?g?L?1). Strain SLHTYROT was methylotrophic methanogen able to use methylated compounds (trimethylamine, dimethylamine, monomethylamine and methanol). Strain SLHTYROT was able to grow at in situ hydrostatic pressure and temperature conditions (35?MPa, 14?°C). Phylogenetic analysis based on 16S rRNA gene and mcrA gene sequences indicated that strain SLHTYROT was affiliated to genus Methanohalophilus within the order Methanosarcinales. It shared >99.16% of the 16S rRNA gene sequence similarity with strains of other Methanohalophilus species. Based on ANIb, AAI and dDDH measurements, and the physiological properties of the novel isolate, we propose that strain SLHTYROT should be classified as a representative of a novel species, for which the name Methanohalophilus profundi sp. nov. is proposed; the type strain is SLHTYROT (=DSM 108854?=?JCM 32768?=?UBOCC-M-3308).??cki, M.K., Valkenborg, D., Startek, M.P., 2020. IsoSpec2: Ultrafast fine structure calculator. Analytical Chemistry 92, 9472-9475. mass spectrometry becomes increasingly available with its ability to resolve the fine isotopic structure of measured analytes. It allows for high-sensitivity spectral deconvolution, leading to less false-positive identifications. Analytes can be identified by comparing their theoretical isotopic signal with the observed peaks. Necessary calculations are, however, computationally demanding and lead to long processing times. For wheat (trictum oestivum) alone, Uniprot holds more than 142?000 candidate protein sequences. This is doubled upon sequence reversal for identification FDR estimation and further multiplied by performing in silico digestion into peptides. The same peptide might originate from more than one protein, which reduces the overall number of sequences to be calculated. However, it is still huge. IsoSpec2 can perform these calculations fast. Compared to IsoSpec1, the algorithm is simpler, orders of magnitude faster, and offers more flexibility for the developers of algorithms for raw data analysis. It is freely available under a 2-clause BSD license, with bindings for the C++, C, R, and Python programming languages.Lane, D., Bermel, W., Ning, P., Jeong, T.-Y., Martin, R., Soong, R., Wu, B., Tabatabaei-Anaraki, M., Heumann, H., Gundy, M., Boenisch, H., Adamo, A., Arhonditsis, G., Simpson, A.J., 2020. Targeting the lowest concentration of a toxin that induces a detectable metabolic response in living organisms: Time-resolved in vivo 2D NMR during a concentration ramp. Analytical Chemistry 92, 9856-9865. vivo nuclear magnetic resonance (NMR) is a powerful analytical tool for probing complex biological processes inside living organisms. However, due to magnetic susceptibility broadening, which produces broad lines in one-dimensional NMR, 1H–13C two-dimensional (2D) NMR is required for metabolite monitoring in vivo. As each 2D experiment is time-consuming, often hours, this limits the temporal resolution over which in vivo processes can be monitored. Furthermore, to understand concentration-dependent responses, studies are traditionally repeated using different contaminant and toxin concentrations, which can make studies prohibitively long (potentially months). In this study, time-resolved non-uniform sampling NMR is performed in the presence of a contaminant concentration sweep. The result is that the lowest concentration that elicits a metabolic response can be rapidly detected, while the metabolic pathways impacted provide information about the toxic mode of action of the toxin. The lowest concentration of bisphenol A (BPA) that induces a response was ～0.1 mg/L (detected in just 16 min), while changes in different metabolites suggest a complex multipathway response that leads to protein degradation at higher BPA concentrations. This proof of concept shows it is possible, on the basis of “real-time” organism responses, to identify the sublethal concentration at which a toxin impacts an organism and thus represents an essential analytical tool for the next generation of toxicity-based research and monitoring.Larrea-Alvarez, M., Purton, S., 2020. Multigenic engineering of the chloroplast genome in the green alga Chlamydomonas reinhardtii. Microbiology 166, 510-515. chloroplast of microalgae such as Chlamydomonas reinhardtii represents an attractive chassis for light-driven production of novel recombinant proteins and metabolites. Methods for the introduction and expression of transgenes in the chloroplast genome (=plastome) of C. reinhardtii are well-established and over 100 different proteins have been successfully produced. However, in almost all reported cases the complexity of the genetic engineering is low, and typically involves introduction into the plastome of just a single transgene together with a selectable marker. In order to exploit fully the potential of the algal chassis it is necessary to establish methods for multigenic engineering in which many transgenes can be stably incorporated into the plastome. This would allow the synthesis of multi-subunit proteins and the introduction into the chloroplast of whole new metabolic pathways. In this short communication we report a proof-of-concept study involving both a combinatorial and serial approach, with the goal of synthesizing five different test proteins in the C. reinhardtii chloroplast. Analysis of the various transgenic lines confirmed the successful integration of the transgenes and accumulation of the gene products. However, the work also highlights an issue of genetic instability when using the same untranslated region for each of the transgenes. Our findings therefore help to define appropriate strategies for robust multigenic engineering of the algal chloroplast.Lawrence, K.T., Pearson, A., Casta?eda, I.S., Ladlow, C., Peterson, L.C., Lawrence, C.E., 2020. Comparison of Late Neogene U37K' and TEX86 paleotemperature records from the Eastern Equatorial Pacific at orbital resolution. Paleoceanography and Paleoclimatology 35, e2020PA003858.: Key features of late Neogene climate remain uncertain due to conflicting records derived from different sea surface temperature (SST) proxies. To understand scenarios in which proxy‐derived temperature estimates can be used interchangeably or are instead measuring different aspects of the same system, it is necessary to explore both the consistencies and differences between specific paleothermometers. Here, we report orbital‐scale climate records from ODP Site 846 in the eastern equatorial Pacific (EEP) for the interval from ~5–6 Ma using alkenone and archaeal lipid paleothermometers. Results from both proxies are similar in their secular trends and magnitude of long‐term temperature change, and spectral analysis demonstrates that the records are coherent and in‐phase in both the obliquity and precession bands. However, we find that the temperatures reconstructed by TEX86 are consistently offset toward colder values by ~2?°C relative to U37K' ‐derived temperatures in global calibrations, or by ~0.8?°C in Bayesian‐based calibrations. All combinations of calibrations also yield approximately twice the amplitude of orbital‐scale variation in TEX86 relative to U37K' ‐derived temperature fluctuations. Both temperature proxies are negatively correlated with sedimentary alkenone concentrations, which we use as an indicator of increased export productivity. Removing this productivity contribution from TEX86 results in an adjusted TEX86 record with temperature sensitivity identical to Uk′37. In future applications, this signal may be decoupled using additional sedimentary indicators of paleoproductivity, which likely will be most important for upwelling zone environments. There remain other nonexplained factors that contribute to differences between TEX86 and U37K' that warrant additional investigation.Plain Language Summary: The remains of organisms found in ocean sediments contain information about the climate at the time the organisms were alive. Some of these remains enable the reconstruction of past temperature and are used as “paleothermometers.” Many different types of paleothermometers exist; however, none work across all time periods or geographic locations. Thus, data from different paleothermometers are commonly used interchangeably to study Earth's past climate. However, little previous work has been done to study the limitations of this approach. Two of the most widely used paleothermometers are based on lipids of marine microorganisms. Here, we generated high‐resolution temperature reconstructions using both techniques. This allowed us to compare the timing, direction, and magnitude of the reconstructed temperature changes over a time interval of nearly 1 million years. Encouragingly, both paleothermometers show the same general patterns through time, although they yield modestly different results. These differences are greater during cold climate conditions and appear to be in part due to the influence of the amount of local biological productivity on one of the paleothermometers. We propose some ways that the contribution of factors other than temperature, including not only productivity but also community composition, might be explored in the future.Le, V.-H., Caumon, M.-C., Tarantola, A., Randi, A., Robert, P., Mullis, J., 2020. Calibration data for simultaneous determination of P-V-X properties of binary and ternary CO2 - CH4 - N2 gas mixtures by Raman spectroscopy over 5–600?bar: Application to natural fluid inclusions. Chemical Geology 552, 119783. P-V-X properties of two-component fluid inclusions (FIs) are generally determined from microthermometry data using appropriate thermodynamic models (i.e., VX diagrams) and/or equations of state (EoS). However, some limitations can hamper the applicability of this technique such as the small size, low density or complex composition of the analyzed FI. Raman spectroscopy is known as the best-suited alternative method to microthermometry for the investigation of natural FIs because it can provide simultaneously non-destructive qualitative and possible quantitative analyses after specific calibrations. The present work aims to provide calibration data to directly determine the P-V-X properties of binary or ternary mixtures of CH4, CO2, and N2. The variation of spectral features as a function of composition and pressure (or density) was investigated by using Raman spectroscopy coupled with an improved High-Pressure Optical Cell (HPOC) system and a customized heating-cooling stage. From our experimental data, the relative Raman scattering cross-section (RRSCS) of CH4 (νCH4?) was demonstrated to be constant at 7.73?±?0.16 over the investigated range of pressure (5–600?bars) and for any composition. This parameter can thus be used for the determination of composition with an uncertainty of ~0.5?mol%. Several calibration equations were calculated for different PX domains, linking the Fermi diad splitting of CO2 (Δ) or the relative variation of the CH4 peak position (νCH4?) to the pressure (or density) and composition of CO2-CH4, CH4-N2, and CO2-N2-CH4 mixtures at 22 and 32?°C. The pressure and density of the fluids can henceforth be directly measured from Raman spectra with an uncertainty of ~20 bars and ~0.01?g·cm?3, respectively. Our calibration equations were then validated on natural FIs by comparing the results obtained from Raman and microthermometry. We also interpreted the variation of the peak position of CH4 based on the change of intermolecular interaction. Finally, we discussed the applicability of the obtained calibration data into another laboratory by comparing it with the data of pure CO2 and CH4 published in literature. A small shift between calibration curves implies a systematic error which is perhaps due to the difference in the configuration or the day-to-day deviation of the instruments. Therefore, standards of well-known P-V-X properties should be regularly measured to prevent and to correct any variation or shifting of the instrumental responses.Leewis, M.-C., Berlemont, R., Podgorski, D.C., Srinivas, A., Zito, P., Spencer, R.G.M., McFarland, J., Douglas, T.A., Conaway, C.H., Waldrop, M., Mackelprang, R., 2020. Life at the frozen limit: Microbial carbon metabolism across a Late Pleistocene permafrost chronosequence. Frontiers in Microbiology 11, 1753. doi: 10.3389/fmicb.2020.01753. is an extreme habitat yet it hosts microbial populations that remain active over millennia. Using permafrost collected from a Pleistocene chronosequence (19 to 33 ka), we hypothesized that the functional genetic potential of microbial communities in permafrost would reflect microbial strategies to metabolize permafrost soluble organic matter (OM) in situ over geologic time. We also hypothesized that changes in the metagenome across the chronosequence would correlate with shifts in carbon chemistry, permafrost age, and paleoclimate at the time of permafrost formation. We combined high-resolution characterization of water-soluble OM by Fourier-transform ion-cyclotron-resonance mass spectrometry (FT-ICR MS), quantification of organic anions in permafrost water extracts, and metagenomic sequencing to better understand the relationships between the molecular-level composition of potentially bioavailable OM, the microbial community, and permafrost age. Both age and paleoclimate had marked effects on both the molecular composition of dissolved OM and the microbial community. The relative abundance of genes associated with hydrogenotrophic methanogenesis, carbohydrate active enzyme families, nominal oxidation state of carbon (NOSC), and number of identifiable molecular formulae significantly decreased with increasing age. In contrast, genes associated with fermentation of short chain fatty acids (SCFAs), the concentration of SCFAs and ammonium all significantly increased with age. We present a conceptual model of microbial metabolism in permafrost based on fermentation of OM and the buildup of organic acids that helps to explain the unique chemistry of ancient permafrost soils. These findings imply long-term in situ microbial turnover of ancient permafrost OM and that this pooled biolabile OM could prime ancient permafrost soils for a larger and more rapid microbial response to thaw compared to younger permafrost soils.Legendre, L.J., Rubilar-Rogers, D., Musser, G.M., Davis, S.N., Otero, R.A., Vargas, A.O., Clarke, J.A., 2020. A giant soft-shelled egg from the Late Cretaceous of Antarctica. Nature 583, 411-414. size and structure reflect important constraints on the reproductive and life-history characteristics of vertebrates. More than two-thirds of all extant amniotes lay eggs. During the Mesozoic era (around 250 million to 65 million years ago), body sizes reached extremes; nevertheless, the largest known egg belongs to the only recently extinct elephant bird, which was roughly 66 million years younger than the last nonavian dinosaurs and giant marine reptiles. Here we report a new type of egg discovered in nearshore marine deposits from the Late Cretaceous period (roughly 68 million years ago) of Antarctica. It exceeds all nonavian dinosaur eggs in volume and differs from them in structure. Although the elephant bird egg is slightly larger, its eggshell is roughly five times thicker and shows a substantial prismatic layer and complex pore structure. By contrast, the new fossil, visibly collapsed and folded, presents a thin eggshell with a layered structure that lacks a prismatic layer and distinct pores, and is similar to that of most extant lizards and snakes (Lepidosauria). The identity of the animal that laid the egg is unknown, but these preserved morphologies are consistent with the skeletal remains of mosasaurs (large marine lepidosaurs) found nearby. They are not consistent with described morphologies of dinosaur eggs of a similar size class. Phylogenetic analyses of traits for 259 lepidosaur species plus outgroups suggest that the egg belonged to an individual that was at least 7 metres long, hypothesized to be a giant marine reptile, all clades of which have previously been proposed to show live birth. Such a large egg with a relatively thin eggshell may reflect derived constraints associated with body shape, reproductive investment linked with gigantism, and lepidosaurian viviparity, in which a ‘vestigial’ egg is laid and hatches immediately.Lehmann, J., Hansel, C.M., Kaiser, C., Kleber, M., Maher, K., Manzoni, S., Nunan, N., Reichstein, M., Schimel, J.P., Torn, M.S., Wieder, W.R., K?gel-Knabner, I., 2020. Persistence of soil organic carbon caused by functional complexity. Nature Geoscience 13, 529-534. organic carbon management has the potential to aid climate change mitigation through drawdown of atmospheric carbon dioxide. To be effective, such management must account for processes influencing carbon storage and re-emission at different space and time scales. Achieving this requires a conceptual advance in our understanding to link carbon dynamics from the scales at which processes occur to the scales at which decisions are made. Here, we propose that soil carbon persistence can be understood through the lens of decomposers as a result of functional complexity derived from the interplay between spatial and temporal variation of molecular diversity and composition. For example, co-location alone can determine whether a molecule is decomposed, with rapid changes in moisture leading to transport of organic matter and constraining the fitness of the microbial community, while greater molecular diversity may increase the metabolic demand of, and thus potentially limit, decomposition. This conceptual shift accounts for emergent behaviour of the microbial community and would enable soil carbon changes to be predicted without invoking recalcitrant carbon forms that have not been observed experimentally. Functional complexity as a driver of soil carbon persistence suggests soil management should be based on constant care rather than one-time action to lock away carbon in soils.Lehmann, J., Possinger, A., 2020. Removal of atmospheric CO2 by rock weathering holds promise for mitigating climate change. Nature 583, 204-205. removal of carbon dioxide from the atmosphere might be achieved through enhanced rock weathering. It now seems that this approach is as promising as other strategies, in terms of cost and CO2-removal potential. Achieving targets for mitigating global warming will require the large-scale withdrawal of carbon dioxide from the atmosphere. Writing in Nature, Beerling et al.1 report that enhanced rock weathering in soils has substantial technical and economic potential as a global strategy for removing atmospheric CO2. When crushed basalt or other silicate material is added to soil, it slowly dissolves and reacts with CO2 to form carbonates. These either remain in the soil or move towards the oceans. The authors argue that this method would enable between 0.5 billion and 2 billion tonnes of CO2 to be removed from the atmosphere each year. This rate is similar to that of other land-based approaches2, such as the accrual of organic carbon in soil, carbon capture and sequestration in geological formations, and the addition of biochar (a carbon-rich material) to soil.Beerling and colleagues find that removing atmospheric CO2 through enhanced rock weathering would cost, on average, US$160–190 per tonne of CO2 in the United States, Canada and Europe, and $55–120 per tonne of CO2 in China, India, Mexico, Indonesia and Brazil. Furthermore, the authors report that China, the United States and India — the three largest emitters of CO2 from fossil-fuel use — have the highest potential for CO2 removal using this method. However, they also note that the application of silicate material to soil (Fig. 1) requires careful assessment of the risks, such as the possible release of metals and persistent organic compounds (compounds resistant to environmental degradation).Despite the enthusiasm the authors’ findings might generate, it is crucial to stress that, even under optimistic assumptions, enhanced rock weathering will sequester only some of the annual global carbon emissions from fossil-fuel use. Therefore, reducing these emissions should still be the top priority for averting dangerous climate change. But, as Beerling et al. note, any approach is insufficient alone, and should be considered as part of a portfolio of options.Several other land-based carbon-sequestration techniques rely on soils. However, inorganic-carbon sequestration by rock weathering is fundamentally different from organic-carbon sequestration. The latter relies on photosynthesis by plants to remove CO2 from the atmosphere, and on soils to retain the plant carbon, mostly in the form of microbial remains. In the future, therefore, scientists should pay closer attention to what they mean by ‘carbon sequestration’ — is it inorganic or organic?The sequestration of atmospheric CO2 through enhanced rock weathering shares some of the principal appeal, but also the challenges, of organic-carbon sequestration. The fact that crop production benefits is certainly a key asset of both methods. In the case of enhanced rock weathering, the added rock contains essential plant nutrients, such as calcium and magnesium, as well as potassium and micronutrients that promote crop production in several ways. We would go even further than the authors do, to claim that these nutrients are currently insufficiently supplied in agriculture.Increasing soil pH alone would substantially boost crop yields in many regions of the world, because it is possible that low pH constrains crop production on more than 200 million hectares of arable and orchard soils3. This area is equivalent to about 20% of the total extent of these soils (967 million hectares; see go.31rcajd). Consequently, on a global scale, acidity is the most important soil constraint for agriculture4. However, there have been no detailed multi-regional analyses of the difference in crop yield between low-pH and optimum-pH soils, and such investigations would benefit the study of synergies between carbon-sequestration methods. The proposed rock additions could conceivably mitigate the low use and supply shortages of agricultural limestone in several regions5. Furthermore, calcium improves root growth in acidic subsurface soil6, with crucial knock-on effects through greater water uptake by plant roots.Co-deployment of enhanced rock weathering with other soil-based sequestration approaches might both reduce limitations and maximize synergies7. Beerling and colleagues’ study hints at some of these opportunities and at constraints that have procedural and soil-biogeochemical aspects. Greater crop growth will increase the input of crop residue (the materials from crops that are left in a field after harvesting) to the soil, and thereby enhance the accrual of organic carbon. However, the possibility that interactions between calcium and organic matter impede the return of CO2 to the atmosphere has been sparsely explored, and there is little information on the effects of magnesium. In principle, calcium can reduce the decomposition of organic matter by facilitating adsorption to clay, inclusion in carbonates or aggregation8. But the indirect effects of calcium through changes in microbial ecology or interactions with organic compounds, rather than interactions only between organic compounds and clay minerals, are rarely studied.If the synergy becomes a trade-off between organic-carbon sequestration and crop production, the organic-carbon content of soil could decrease, threatening the livelihoods of farmers, and even food security. Any carbon sequestration involving soils is a formidable challenge to incentivize, predict and monitor9, because the sequestration technologies must be used on vast areas of land that are operated by hundreds of millions of farmers. Inevitably, there will be individual cases in which positive-yield projections are not met or crop yields even decrease, where incentives fail to persuade farmers, or where supply chains break down. But scientists should not be deterred from evaluating such technologies, and should instead accept that farmers need to be in the driving seat in adapting soil management to meet their specific site and crop-production goals. A concerted global effort will be required to develop site-specific optimization through farmer-centred research.Fertilizer distribution networks are common in many parts of the world. But even where these networks are in place, success in the adoption of enhanced rock weathering might not rely on its crop-production benefits alone. We posit that carbon markets are required, and that it would be helpful if they incentivized socially and environmentally sound implementation10. For technologies to be eligible, it must be shown that they provide extra incentives for adoption (additionality), beyond what increased soil fertility would deliver. We emphasize that implementation of enhanced rock weathering and other soil-based carbon sequestration must consider equitable and financially sound incentives for farmers that overcome challenges of additionality, among others10, in a proactive way.Consequently, the main lesson here might be that several of the major potential technologies for removing atmospheric CO2 could generate substantial benefits for food production, and are centred around managing soils. Farmers must be fully behind such a global effort or it will fail. Scientists might need to recognize that climate-change mitigation is not a sufficient incentive on its own, and that benefits to crop growth will need to be prioritized, as will financial incentives. Such an approach of financially supporting soil health and crop production could emerge as our best near-term solution to the problem of removing CO2 from the atmosphere.References1. Beerling, D. J. et al. Nature 583, 242–248 (2020).2. Pacala, S. et al. Negative Emissions Technologies and Reliable Sequestration: A Research Agenda (National Academy of Sciences, 2018).3. von Uexküll, H. R. & Mutert, E. Plant Soil 171, 1–15 (1995).4. Wood, S., Sebastian, K. & Scherr, S. J. Pilot Analysis of Global Ecosystems: Agroecosystems (World Resources Inst., 2000).5. Fabregas, R., Fabregas, M., Robinson, J. & Schilbach, F. Evaluating Agricultural Information Dissemination in Western Kenya (International Initiative for Impact Evaluation, 2017).6. Lynch, J. P. & Wojciechowski, T. J. Exp. Bot. 66, 2199–2210 (2015).7. Amann, T. & Hartmann, J. Biogeosciences 16, 2949–2960 (2019).8. Rowley, M. C., Grand, S. & Verrecchia, ?. P. Biogeochemistry 137, 27–49 (2018).9. Bradford, M. A. et al. Nature Sustain. 2, 1070–1072 (2019).10. Cavanagh, C. J., Vedeld, P. O., Petursson, J. G. & Chemarum, A. K. J. Peasant Stud. (2020).Leng, L., Zhang, W., Peng, H., Li, H., Jiang, S., Huang, H., 2020. Nitrogen in bio-oil produced from hydrothermal liquefaction of biomass: A review. Chemical Engineering Journal 401, 126030. liquefaction (HTL) of biomass, especially that of high moisture such as microalgae, macroalgae, sludge, manure, and food waste, for the production of bio-oil has been widely concerned worldwide. However, the contents of nitrogen (N) in these biomasses are commonly high, and 20–40% of the N in the raw biomasses would distribute into bio-oil during the HTL process, resulting in a high content of N in bio-oil, sometimes up to 10 wt%. The combustion of N-rich bio-oil will probably induce massive emission of nitrogen oxides. The transformation behavior of N has not yet been fully understood, and the denitrogenation is a critical issue during bio-oil production and upgrading. This review comprehensively summarized the effects of the type, composition, and pretreatment of biomass and HTL processing parameters, such as temperature, residence time, solid loading, reaction solvent, extraction solvent/procedure, and catalyst, on the N content of bio-oil. The N conversion mechanisms in the HTL process were also clarified. Research gaps were identified, and future research directions were finally proposed to achieve the production of bio-oil with low N content.Lewis, C.G., Beazley, M.J., 2020. Impacts of dibenzopyrenes on bacterial community isolated from Gulf of Mexico sediment. MicrobiologyOpen 9, e1039. presence of polycyclic aromatic hydrocarbons (PAHs) in marine environments as a result of contamination is an environmental concern, especially in regions where oil spills such as the Deepwater Horizon have occurred. While numerous PAHs have been studied for their effects on microbes, the family of dibenzopyrenes has yet to be investigated. In this preliminary study, the impacts of these molecules on the community structure of a bacterial consortium isolated from oil‐impacted Gulf of Mexico sediment were examined using high‐throughput sequencing, demonstrating intriguing negative impacts on species diversity and abundance. While no measurable degradation of the dibenzopyrenes was observed after 28‐day incubation, the abundance of known oil‐degrading bacteria from orders such as Oceanospirillales, Caulobacterales, Sphingomonadales, and Nitrosococcales were shown to be enhanced. Of the five isomers of dibenzopyrene studied, dibenzo[a,h ]pyrene supported the fewer number of microbial species suggesting the isomer was more toxic compared to the other isomers.Lewis, K.M., van Dijken, G.L., Arrigo, K.R., 2020. Changes in phytoplankton concentration now drive increased Arctic Ocean primary production. Science 369, 198-202.: Historically, sea ice loss in the Arctic Ocean has promoted increased phytoplankton primary production because of the greater open water area and a longer growing season. However, debate remains about whether primary production will continue to rise should sea ice decline further. Using an ocean color algorithm parameterized for the Arctic Ocean, we show that primary production increased by 57% between 1998 and 2018. Surprisingly, whereas increases were due to widespread sea ice loss during the first decade, the subsequent rise in primary production was driven primarily by increased phytoplankton biomass, which was likely sustained by an influx of new nutrients. This suggests a future Arctic Ocean that can support higher trophic-level production and additional carbon export.Editor's Summary: Food for thought. Phytoplankton abundances in the Arctic Ocean have been increasing over recent decades as the region has warmed and sea ice has disappeared. The presumptive causes of this increase were expanding open water area and a longer growing season—at least until now. Lewis et al. show that although these factors may have driven the productivity trends before, over the past decade, phytoplankton primary production rose by more than half because of increased phytoplankton concentrations (see the Perspective by Babin). This finding means that there has been an influx of new nutrients into the region, suggesting that the Arctic Ocean could become more productive and export additional carbon in the future.Li, C., Pang, X., Huo, Z., Wang, E., Xue, N., 2020. A revised method for reconstructing the hydrocarbon generation and expulsion history and evaluating the hydrocarbon resource potential: Example from the first member of the Qingshankou Formation in the Northern Songliao Basin, Northeast China. Marine and Petroleum Geology 121, 104577. the hydrocarbon generation and expulsion history of source rocks is an essential part of evaluating the hydrocarbon resource potential by genetic method. The hydrocarbon generation potential method is an efficient tool for quantifying the hydrocarbon generation and expulsion characteristics of source rock and evaluating the hydrocarbon resource potential based on Rock-Eval data. Although various revised versions of the method are publicly available, the following problems remain to be resolved: (a) the method is subjective; (b) implicit limitations are observed; and (c) rock mass loss is not considered, which may result in unacceptable errors. In this study, we propose a revised hydrocarbon generation potential method. Expressions for calculating the original rock mass (Go), original total organic carbon (TOCo), transformation ratio (TR), hydrocarbon expulsion ratio (ER) and hydrocarbon expulsion efficiency (f) were developed and incorporated into the hydrocarbon generation and expulsion history reconstruction and hydrocarbon resource potential evaluation, and these expressions combined conventional and unconventional resource evaluations systematically with objective and accurate results. The first member of the Qingshankou Formation (K2qn1) in the Northern Songliao Basin, Northeast China, was used as an example to demonstrate the application of the proposed method. The results have been compared with the unrevised method using the same Rock-Eval data sets and verified with previous reports to demonstrate its reliability. The results also indicate that the hydrocarbon generation threshold (HGT) and hydrocarbon expulsion threshold (HET) of K2qn1 are Ro = 0.4% and Ro = 0.6%, respectively. Three hydrocarbon generation and expulsion peak stages were identified: K2n (81–74 Ma), K2m (74–66 Ma), and N2t (66–0 Ma). The hydrocarbon generation and expulsion centers of K2qn1 are mainly the Qijia-Gulong Sag and Sanzhao Sag. The resource potentials of conventional oil, unconventional tight oil, and shale oil associated with K2qn1 source rocks in the Northern Songliao Basin are 8.15 × 108 t, 22.97 × 108 t, and 62.1 × 108 t, respectively.Li, C., Shen, H., Sheng, X., Wei, H., Chen, J., 2020. Kinetics and fractionation of carbon and oxygen isotopes during the solid-phase transformation of biogenic aragonite to calcite: The effect of organic matter. Palaeogeography, Palaeoclimatology, Palaeoecology 556, 109876. phase transformation of biogenic shells from aragonite to calcite can modify the primary carbon and oxygen isotopic values (δ13C and δ18O), and thus affect their significance as paleoenvironmental proxies. While the biasing of δ13C and δ18O by dissolution and reprecipitation phase transformation (DR) has been extensively studied, thermal solid-phase transformation (SPT) in archaeological shell middens is rarely considered. In this study, the effects of intra-crystalline organic matter on the kinetics and carbon and oxygen isotopic fractionation during thermal SPT are evaluated by comparing two sets of experiments on powdered aragonite snail shells heated in air and pure nitrogen atmospheres. The results show that during heating temperature below 400 °C, the intra-crystalline organic matter could inhibit the phase transformation due to the shielding effect of organic matter, while during heating temperature above 400 °C, the decomposition of the intra-crystalline organic matter increases the kinetic rate of the phase transformation. The activation energy for the phase transformation was determined to be +150.5 kJ·mol?1, lower than that of +247 kJ·mol?1 obtained for abiogenic polycrystalline aragonite and close to that of +158 to +163 kJ·mol?1 for abiogenic single crystal aragonite. This is attributed to the larger lattice parameter c in biogenic aragonite and the increasing porosity of calcium carbonate with the decomposition of organic matter. In a nitrogen atmosphere, the deviation of δ13C and δ18O between the heated sample (the mixture of aragonite and calcite) and the original shell aragonite (Δ13CM-A and Δ18OM-A) is negligible during heating temperature below 400 °C; however, Δ13CM-A (from ?0.43‰ to 0.00‰) and Δ18OM-A (from ?1.54‰ to ?0.02‰) are significant during heating temperature above 400 °C. The temperature-dependence of Δ13CM-A in biogenic carbonates is much more significant than that in abiogenic carbonates, which clearly reflects the occurrence of isotopic exchange between the intra-crystalline organic matter and the carbonates. In air, the heating-induced calcium carbonate is depleted in δ13C by up to ?0.48‰ and in δ18O by up to ?3.46‰, compared with the original samples, which is mainly caused by isotopic exchange with the external carbon dioxide in air and the intra-crystalline organic matter, with the latter being the dominant source. Our results demonstrate that the decomposition of the intra-crystalline organic matter increases the kinetic rate and induces carbon and oxygen isotope fractionation during SPT from aragonite to calcite. This study provides direct evidence for evaluating the preservation of carbon and oxygen isotopes of biogenic calcium carbonate shells which have undergone the SPT process in archaeological shell middens.Li, H., Yang, Q., Zhou, H., 2020. Niche differentiation of sulfate- and iron-dependent anaerobic methane oxidation and methylotrophic methanogenesis in deep sea methane seeps. Frontiers in Microbiology 11, 1409. doi: 10.3389/fmicb.2020.01409. seeps are widespread seafloor ecosystems shaped by complex physicochemical-biological interactions over geological timescales, and seep microbiomes play a vital role in global biogeochemical cycling of key elements on Earth. However, the mechanisms underlying the coexistence of methane-cycling microbial communities remain largely elusive. Here, high-resolution sediment incubation experiments revealed a cryptic methane cycle in the South China Sea (SCS) methane seep ecosystem, showing the coexistence of sulfate (SO42–)- or iron (Fe)-dependent anaerobic oxidation of methane (AOM) and methylotrophic methanogenesis. This previously unrecognized methane cycling is not discernible from geochemical profiles due to high net methane consumption. High-throughput sequencing and Catalyzed Reporter Deposition-Fluorescence in situ Hybridization (CARD-FISH) results suggested that anaerobic methane-oxidizing archaea (ANME)-2 and -3 coupled to sulfate-reducing bacteria (SRB) carried out SO42–-AOM, and alternative ANME-2 and -3 solely or coupled to iron-reducing bacteria (IRB) might participate in Fe-AOM in sulfate-depleted environments. This finding suggested that ANME could alter AOM metabolic pathways according to geochemical changes. Furthermore, the majority of methylotrophic methanogens belonged to Methanimicrococcus, and hydrogenotrophic and acetoclastic methanogens were likely inhibited by sulfate or iron respiration. Fe-AOM and methylotrophic methanogenesis are overlooked potential sources and sinks of methane in methane seep ecosystems, thus influencing methane budgets and even the global carbon budget in the ocean.Li, J.-L., Zhang, T.-S., Li, Y.-J., Liang, X., Wang, X., Zhang, J.-H., Zhang, Z., Shu, H.-L., Rao, D.-Q., 2020. Geochemical characteristics and genetic mechanism of the high-N2 shale gas reservoir in the Longmaxi Formation, Dianqianbei Area, China. Petroleum Science 17, 939-953. an important pilot target for shale gas exploration and development in China, the Longmaxi Formation shale in the Dianqianbei Area is characterized by high content of nitrogen, which severely increases exploration risk. Accordingly, this study explores the genesis of shale gas reservoir and the mechanism of nitrogen enrichment through investigating shale gas compositions, isotope features, and geochemical characteristics of associated gases. The high-nitrogen shale gas reservoir in the Longmaxi Formation is demonstrated to be a typical dry gas reservoir. Specifically, the alkane carbon isotope reversal is ascribed to the secondary cracking of crude oil and the Rayleigh fractionation induced by the basalt mantle plume. Such a thermogenic oil-type gas reservoir is composed of both oil-cracking gas and kerogen-cracking gas. The normally high nitrogen content (18.05%–40.92%) is attributed to organic matter cracking and thermal ammoniation in the high-maturity stage. Specifically, the high heat flow effect of the Emeishan mantle plume exacerbates the thermal cracking of organic matter in the Longmaxi Formation shale, accompanied by nitrogen generation. In comparison, the abnormally high nitrogen content (86.79%–98.54%) is ascribed to the communication between the atmosphere and deep underground fluids by deep faults, which results in hydrocarbon loss and nitrogen intrusion, acting as the key factor for deconstruction of the primary shale gas reservoir. Results of this study not only enrich research on genetic mechanism of high-maturity N2 shale gas reservoirs, but also provide theoretical guidance for subsequent gas reservoir resource evaluation and well-drilling deployment in this area.Li, J., Li, B., Ren, C., Zhang, Y., Wang, B., 2020. An adsorption model for evaluating methane adsorption capacity in shale under various pressures and moisture. Journal of Natural Gas Science and Engineering 81, 103426. generally contains water that has a significant effect on the adsorption of methane in shale. Since methane in shale is mostly stored in an adsorbed state, understanding the effect of moisture on shale adsorption behavior will play a vital role in shale gas development. In this paper, an adsorption model has been proposed to consider the effects of moisture to describe the methane adsorption behavior in wet shale. The model modified the actual methane gas pressure in reservoirs, which to evaluate accurately the methane adsorption levels in the reservoir. Moreover, the model also quantitatively described the degree of influence that moisture in shale had on the amount of shale methane adsorbed. Published data have been used to further verify the applicability of the model. Results have shown that, during a change in gas pressure, the methane adsorption amount in shale revealed a typical “three-stage” change law. With an increase in moisture, the methane adsorption level decreased linearly owing to the inhibitory effect of water molecules on methane adsorption. In terms of test data matching, the calculated results of the model were in approximate agreement with the measured values, indicating that the model could better describe the adsorption behavior in aquifers. Additionally, the classic Langmuir model, the Langmuir-Freundlich model, and the D-A model have been used as comparison with the proposed model in this paper. The comparison results showed that the model proposed in this paper could better quantify the effects of moisture on methane adsorption. And it possessed advantages over models, such as the Langmuir one, under high pressure conditions. In addition, because of the hydrophilic nature of shale, methane could only be adsorbed at a lower energy adsorption site, which indicated that the adsorption heat on wet shale was significantly lower than that in dry shale.Li, J., Menguy, N., Roberts, A.P., Gu, L., Leroy, E., Bourgon, J., Yang, X.a., Zhao, X., Liu, P., Changela, H.G., Pan, Y., 2020. Bullet-shaped magnetite biomineralization within a magnetotactic Deltaproteobacterium: Implications for magnetofossil identification. Journal of Geophysical Research: Biogeosciences 125, e2020JG005680.: Magnetite produced by magnetotactic bacteria (MTB) provides stable paleomagnetic signals because it occurs as natural single‐domain magnetic nanocrystals. MTB can also provide useful paleoenvironmental information because their crystal morphologies are associated with particular bacterial groups and the environments in which they live. However, identification of the fossil remains of MTB (i.e., magnetofossils) from ancient sediments or rocks is challenging because of their generally small sizes and because the growth, morphology, and chain assembly of magnetite within MTB are not well understood. Nanoscale characterization is, therefore, needed to understand magnetite biomineralization and to develop magnetofossils as biogeochemical proxies for paleoenvironmental reconstructions. Using advanced transmission electron microscopy, we investigated magnetite growth and chain arrangements within magnetotactic Deltaproteobacteria strain WYHR‐1, which reveals how the magnetite grows to form elongated, bullet‐shaped nanocrystals. Three crystal growth stages are recognized: (i) initial isotropic growth to produce nearly round ~20 nm particles, (ii) subsequent anisotropic growth along the [001] crystallographic direction to ~75 nm lengths and ~30–40 nm widths, and (iii) unidirectional growth along the [001] direction to ~180 nm lengths, with some growing to ~280 nm. Crystal growth and habit differ from that of magnetite produced by other known MTB strains, which indicates species‐specific biomineralization. These findings suggest that magnetite biomineralization might be much more diverse among MTB than previously thought. When characterized adequately at species level, magnetofossil crystallography, and apomorphic features are, therefore, likely to become useful proxies for ancient MTB taxonomic groups or species and for interpreting the environments in which they lived.Plain Language Summary: Biomineralization is a widespread process that provides living organisms with mineralized skeletons and organelles. Biominerals are mainly responsible for Earth's fossil record. As a striking example of microbial biomineralization, magnetotactic bacteria form intracellular chains of magnetic nanocrystals that they use to sense Earth's magnetic field. Their fossilized remains (magnetofossils) are being used increasingly to reconstruct paleomagnetic and paleoenvironmental information. However, magnetofossil identification remains challenging because magnetite particle growth and chain assembly processes are poorly understood. We report a species‐specific crystal growth and chain arrangement process in a novel magnetotactic strain WYHR‐1. Our findings suggest that magnetofossil crystallography could become a proxy for ancient bacterial taxonomic groups or species and for interpreting the environments in which they lived.Li, L., Wang, Y., Kürschner, W.M., Ruhl, M., Vajda, V., 2020. Palaeovegetation and palaeoclimate changes across the Triassic–Jurassic transition in the Sichuan Basin, China. Palaeogeography, Palaeoclimatology, Palaeoecology 556, 109891. Triassic–Jurassic transition interval is marked by enhanced biotic turnover rates in both marine and terrestrial realms. However, limited data from Asia hampers the understanding of global ecosystem response to the end-Triassic mass extinction event. Here, we present significant vegetation and climate changes across the Triassic–Jurassic transition in the eastern Tethys region (southern China). A detailed palynological study was performed from the Qilixia section of the Sichuan Basin, China, spanning the Upper Triassic (Norian–Rhaetian) (Xujiahe Formation) to the Lower Jurassic (Hettangian–Sinemurian) (lower Zhenzhuchong Formation). Five palynological assemblages reveal significant ecosystem fluctuations across the Triassic–Jurassic transition. Our study indicates a lowland fern flora and a warm and humid climate in the Late Triassic (Norian to Rhaetian), interrupted by a cooler interval at the Norian–Rhaetian transition, and followed by a mixed mid-storey forest under cooler and drier condition in the latest Rhaetian. This is followed by a fern-dominated lowland vegetation and a warmer and drier climate during the Triassic–Jurassic transition, and a flora with abundant cheirolepid conifers in the Hettangian–Sinemurian. These long term changes in vegetation and inferred climatic conditions are comparable with records from the western Tethyan realm, and possibly reflect global terrestrial environmental changes associated with Central Atlantic Magmatic Province volcanism during the Triassic–Jurassic transition.Li, Q., Liu, D., Cai, Y., Zhao, B., Qiu, Y., Zhou, Y., 2020h. Scale-span pore structure heterogeneity of high volatile bituminous coal and anthracite by FIB-SEM and X-ray μ-CT. Journal of Natural Gas Science and Engineering 81, 103443. and quantifying the pore structure at the nano-micro scale is critical for understanding the micro fluid transport and enrichment in coalbed methane (CBM) reservoirs. In this work, the detailed micro-nano scale pore parameters such as pore counts, pore area, pore volume and pore size distribution can be acquired by the focused ion beam-scanning electron microscopy (FIB-SEM) and X-ray computed micro-tomography (X-ray μ-CT) techniques. Meanwhile, the pore network model (PNM) was adopted to describe and quantify the pore throat characteristics, which found that the pore throats of the sample LHG well developed and were conducive to seepage. Additionally, the three-dimensional fractal dimension (D3) by the box-counting method was used to evaluate the pores spatial heterogeneity. The D3 of sample LHG and sample L-1 are 2.23 and 2.04 (for FIB-SEM with pore size of 10 nm–~1000 nm), 2.69 and 2.51 (for X-ray μCT with pore size over 500 nm), respectively. The results indicate that the pore network has self-similarity with a secondary development. The variable trends from tens of nanometers to micrometers through the FIB-SEM and X-ray μCT images. For the relationship between porosity and D3, two opposite trends have emerged. The positive correlation trend should be related to the complex pore structure. The more complex the pore structure is, the higher the porosity is. The negative correlation should be contributed by a lot of mineral-filled pores. Pores filled with minerals that will increase the proportion of small pores and decrease the porosity, which causes that the spatial complexity of the pore networks is increased, and the D3 is increased. Therefore, this work may provide insights into the gas storage and seepage capabilities of CBM reservoirs, and thus will be favorable for enhancing CBM recovery.Li, Y., Fichot, C.G., Geng, L., Scarratt, M.G., Xie, H., 2020. The contribution of methane photoproduction to the oceanic methane paradox. Geophysical Research Letters 47, e2020GL088362.: Although methanogenesis is considered a strictly anaerobic process, oxygen‐replete surface open‐ocean waters are usually supersaturated with methane (CH4), a phenomenon termed the oceanic methane paradox. Here, we report that abiotic methane photoproduction from chromophoric dissolved organic matter (CDOM) significantly contributes to this paradox. Methane photoproduction was observed during solar‐simulated irradiations of various waters collected along the land‐ocean continuum. Methane photoproduction rates decreased seaward, whereas its relative production efficiency and the methane‐to‐carbon‐monoxide (CO) photoproduction ratio (ΔCH4/ΔCO) both followed a reversed trend. Remote‐sensing modeling incorporating a ΔCH4/ΔCO–CDOM absorption relationship yielded an annual methane photoproduction of 118 Gg for the global open ocean, accounting for 20–60% of the open‐ocean methane efflux and being of comparable magnitude to the upper‐ocean methane microbial‐oxidation sink. The photodegradation of CDOM thus plays an important role in maintaining supersaturated methane concentrations in the oxygenated upper ocean and in sustaining oceanic methane emissions to the atmosphere.Plain Language Summary: Methane is the second most important greenhouse gas after carbon dioxide, and the global ocean is a significant source of it to the atmosphere. In aquatic environments, methane is thought to be exclusively produced by microbes that degrade organic matter in the absence of oxygen. Contradictorily, the oxygen‐rich waters of the surface open ocean are almost always supersaturated with methane, containing higher concentrations than deeper in the water column. This apparent contradiction is often called the oceanic methane paradox. Here, we demonstrate that the degradation of dissolved organic matter by sunlight in the surface ocean represents an important mechanism of methane production that is capable of maintaining the supersaturation of methane in the surface ocean and of sustaining methane emissions to the atmosphere on a global scale. This study thus suggests that the photochemical production of methane is an important contributor to the oceanic methane paradox.Li, Y., Tang, S., Zhang, S., Xi, Z., Wang, P., 2020. Biogeochemistry and the associated redox signature of co-produced water from coalbed methane wells in the Shizhuangnan block in the southern Qinshui Basin, China. Energy Exploration & Exploitation 38, 1034-1053. meet the global energy demands, the exploitation of coalbed methane has received increasing attention. Biogeochemical parameters of co-produced water from coalbed methane wells were performed in the No. 3 coal seam in the Shizhuangnan block of the southern Qinshui Basin (China). These biogeochemical parameters were firstly utilized to assess coal reservoir environments and corresponding coalbed methane production. A high level of Na+ and HCO3– and deuterium drift were found to be accompanied by high gas production rates, but these parameters are unreliable to some extent. Dissolved inorganic carbon (DIC) isotopes δ13CDIC from water can be used to distinguish the environmental redox conditions. Positive δ13CDIC values within a reasonable range suggest reductive conditions suitable for methanogen metabolism and were accompanied by high gas production rates. SO42–, NO3– and related isotopes affected by various bacteria corresponding to various redox conditions are considered effective parameters to identify redox states and gas production rates. Importantly, the combination of δ13CDIC and SO42– can be used to evaluate gas production rates and predict potentially beneficial areas. The wells with moderate δ13CDIC and negligible SO42– represent appropriate reductive conditions, as observed in most high and intermediate production wells. Furthermore, the wells with highest δ13CDIC and negligible SO42– exhibit low production rates, as the most reductive environments were too strict to extend pressure drop funnels.Li, Z., Zhang, J., Gong, D., Tan, J., Liu, Y., Wang, D., Li, P., Tong, Z., Niu, J., 2020. Gas-bearing property of the Lower Cambrian Niutitang Formation shale and its influencing factors: A case study from the Cengong block, northern Guizhou Province, South China. Marine and Petroleum Geology 120, 104556. gain a better understanding of the gas-bearing property of Lower Cambrian Niutitang Formation shale and its influencing factors, the shale gas-bearing conditions, gas content, and composition in the Cengong block were investigated in this work based on wells CY1, TX1, and TM1. The Niutitang shale reservoir is characterized by large thickness, abundant organic matter with an average total organic carbon content of 4.74%, and high quartz content averaging 53.9%; therefore, it has good shale gas-bearing potential. The results of water immersion and ignition tests intuitively revealed the existence of shale gas based on the occurrence of continuous dense clusters of bubbles and long flames of 1–2 m. The Langmuir volumes of shale samples from well TM1, which ranged from 1.70 to 5.53 m3/t, were positively associated with TOC content and Brunauer–Emmett–Teller surface area, indicating a strong adsorption capacity and significant adsorbed gas potential. However, large differences were observed among the three wells with regard to gas-bearing properties; wells CY1 and TX1 had average total gas contents of 1.25 and 0.33 m3/t, respectively; the gas composition of well TM1 was dominated by nitrogen (N2), with contents generally exceeding 95%. Furthermore, the gas from well TX1 was mainly composed of methane with an average content exceeding 80%. Burial depth and TOC and quartz contents had significant control on the vertical distribution of gas content, and local tectonic preservation conditions resulted in differences of gas-bearing properties among various wells. The measured, lost, and total gas contents all presented positive correlations with TOC, quartz contents, and porosity, and were negatively related to clay content. The shale formed in deep-water shelf environments had better gas-bearing properties than that formed in shallow-water shelf environments. The broad axis of the box syncline in the Cengong block is a favorable location for shale gas accumulation, and fault development affects the shale gas plane distribution. Because of the influence of faults, the shale of well TM1 had low hydrocarbon content. Furthermore, based on the combined patterns of folds and faults as well as other special specific factors, a classification scheme of shale gas accumulation patterns in South China was developed.Liao, K., Hu, H., Ren, H., 2020. Combined influences of process parameters on microorganism-derived dissolved organic nitrogen (mDON) formation at low temperatures: Multivariable statistical and systematic analysis. Science of The Total Environment 744, 140732. of process parameters is a cost-effective approach to control microorganism-derived dissolved organic nitrogen (mDON) formation in low-temperature biological wastewater conditions. However, the integrated influence of multiple parameters in this process is poorly defined. In this study, mathematical methodology was used to evaluate the combined effects of hydraulic retention time (HRT), solids retention time (SRT), and mixed liquor suspended solids (MLSS) on mDON formation at 8 °C. This study also systematically explored how multiple combinations of those three parameters affected mDON chemodiversity (fluorescent properties and molecular compositions), microbial compositions, and specific relationships between mDON molecules and microbial species in activated sludge systems. Results showed that combined effects significantly controlled the mDON formation at 8 °C (P < .05). The systematic analysis suggested that the multi-parameter effects modulated the distribution of different mDON compositions and shaped the microbial communities. Most bacterial phyla as the generalist and a few as the specialist were displayed in 2487 pairs of strong microbe-mDON connections (|r| ≥ 0.6, P < .05). Moreover, network analysis on microbe-mDON relationships identified the network centers as crucial media in terms of combined effects of process parameters on mDON formation. Our results provide comprehensive insight on the roles of multi-parameter covariation influences in regulating the high complexity of mDON traits and microbe-mDON linkages, thereby highlighting the necessity to focus on the combined effects of process parameters for effective and correct controlling strategies on mDON concentrations.Liao, S., Yao, Y., Wang, L., Wang, K.J., Amaral-Zettler, L., Longo, W.M., Huang, Y., 2020. C41 methyl and C42 ethyl alkenones are biomarkers for Group II Isochrysidales. Organic Geochemistry 147, 104081. are polyunsaturated long-chain methyl or ethyl ketones produced by species in the Isochrysidales, an order of haptophyte algae. Based on phylogenetic data, members of the Isochrysidales have been classified into three groups with each group showing significant differences in alkenone profiles and preferred growth environments. Common carbon chain lengths of alkenones range from 37 to 40. Extended C41 methyl (C41Me) and C42 ethyl (C42Et) alkenones have been reported in hypersaline lakes in China (Lake Alahake and Lake Balikun), Canada (Lake Snakehole) and marine sediments (e.g., ～95?Ma in Blake-Bahama Basin). It is unclear, however, if these extended alkenones are produced by one or more groups of Isochrysidales. Here, we systematically examined alkenones from cultures of Group II (Isochrysis nuda, Isochrysis litoralis, Ruttnera lamellosa, Isochrysis galbana and Tisochrysis lutea) and Group III (Emiliania huxleyi and Gephyrocapsa oceanica) Isochrysidales and environmental samples of Group I Isochysidales. C41Me and C42Et alkenones were found in all Group II species with Isochrysis nuda producing the highest percentages, but not in alkenones produced by Group I nor Group III Isochrysidales. Our results indicate that extended C41Me and C42Et alkenones are specific biomarkers for Group II Isochrysidales. We also report the first temperature calibrations of alkenones for Isochrysis nuda and Isochrysis litoralis using culture experiments, and find temperatures inferred from extended alkenones in Balikun and Alahake surface sediments match warm-season temperatures based on Isochrysis nuda calibrations, which is further corroborated by genomic data indicating the dominance of Isochrysis nuda Isochrysidales.Lin, H., Peddada, S.D., 2020. Analysis of compositions of microbiomes with bias correction. Nature Communications 11, 3514. abundance (DA) analysis of microbiome data continues to be a challenging problem due to the complexity of the data. In this article we define the notion of “sampling fraction” and demonstrate a major hurdle in performing DA analysis of microbiome data is the bias introduced by differences in the sampling fractions across samples. We introduce a methodology called Analysis of Compositions of Microbiomes with Bias Correction (ANCOM-BC), which estimates the unknown sampling fractions and corrects the bias induced by their differences among samples. The absolute abundance data are modeled using a linear regression framework. This formulation makes a fundamental advancement in the field because, unlike the existing methods, it (a) provides statistically valid test with appropriate p-values, (b) provides confidence intervals for differential abundance of each taxon, (c) controls the False Discovery Rate (FDR), (d) maintains adequate power, and (e) is computationally simple to implement.Lin, Y., Wu, N., Li, D., Ling, H.-F., 2020. Heterogeneity in the Ediacaran–Cambrian coastal oceans: a sulphur isotope perspective. Geological Magazine 157, 1112-1120. sulphur isotope compositions of sedimentary pyrites across the Ediacaran–Cambrian (Ed–C) transition and into the early Cambrian from the Xiaotan section, Yunnan, South China, are presented to explore the evolution of the sulphur cycle. The values of δ34Spy range from 13.5 ‰ to 35.8 ‰, and the values of Δ33Spy range from ?0.044 ‰ to 0.063 ‰. The first-order observation of highly positive δ34Spy is consistent with sulphur isotope records from other sedimentary successions (with various degrees of enrichment in 34S), reflecting a common feature in cycling of sulphur among ocean basins. The positive values suggest that pyrite was formed in a depositional setting with limiting availability of sulphate that suppressed the expression of microbial fractionations. The first-order observation of a 10-million-year period of negative Δ33Spy beginning around the Ed–C boundary likely reflects changes in isotopic compositions of sulphur influx to the oceans. Such changes are suggested to be linked to a pulse of preferred weathering of sulphides (with negative Δ33S) relative to sulphate, which may reflect enhanced exposure of pyrites in continental margins due to reorganization of continents at this time. Both δ34Spy and Δ33Spy data imply low seawater sulphate levels, and possibly heterogeneity in sulphate concentrations in the world’s coastal oceans. The predictions about sulphur isotope signatures of evolved seawater (with highly positive δ34S and negative Δ33S) at the Xiaotan section are testable with future measurements of carbonate-associated sulphate (CAS), a proxy of ancient oceanic sulphate that carries information about the operation of sulphur cycling on a global scale.Lindgren, J., Kear, B.P., 2020. Hard evidence from soft fossil eggs. Nature 583, 365-366. is thought that dinosaurs laid hard-shelled eggs, whereas ancient marine reptiles gave birth to live young. However, new discoveries of fossilized soft-shelled eggs challenge these long-held tenets of reproductive evolution. The appearance of the amniotic egg marks a key event in the evolutionary history of vertebrates. Its major adaptive advantage is the amnion — an enclosing membrane that prevents the embryo from drying out, and the principal feature to which the amniotic egg owes its name. Another crucial development was the addition of a tough outer shell that provides protection and mechanical support. This allowed the first reptiles to colonize terrestrial environments more than 300 million years ago, and paved the way for the rise of birds and mammals.Because hard-shelled, calcareous eggs, like those of birds, are reinforced by crystalline calcium carbonate, they are well represented in the fossil record. By contrast, soft-shelled eggs, such as those of most lizards and snakes, have leathery outer coverings that decay rapidly and thus are only rarely preserved. Writing in Nature, Norell et al.1 and Legendre et al.2 describe multimillion-year-old soft-shelled eggs that might alter the prevailing view of dinosaur reproduction, and possibly also change current thinking about ancient marine reptiles.Since their earliest documentation in 1859, dinosaur eggs and eggshells have been found almost worldwide, and occasionally even include the remains of associated embryos3. Discoveries indicating communal nesting3 and brooding4 have also revealed the antiquity of bird-like parenting behaviours in dinosaurs. Yet, despite research shedding light on the biochemistry5 and coloration6 of fossil eggs, the known diversity of egg-laying dinosaurs is still limited to only a few groups, including the gigantic sauropods, carnivorous theropods and duck-billed hadrosaurs. Moreover, most dinosaur eggs are geologically rather young, being derived from rocks of Cretaceous age3 — the last and longest period of the Mesozoic era, lasting from about 145 million to 66 million years ago.Given that modern crocodiles and birds lay hard-shelled eggs, the conventional assumption has been that their close ancient relatives, the dinosaurs, must have likewise produced eggs that had calcareous shells, although this is at odds with the puzzling variety of shell microstructures evident between different dinosaur groups. Norell and colleagues now propose that such anatomical inconsistencies arose because calcareous eggs evolved independently at least three times in dinosaurs, and in each instance might have developed from a different type of ancestral soft-shelled egg.Norell et al. base their conclusions on microstructural and organochemical data obtained from non-calcareous fossil eggs (Fig. 1) containing embryos of the sauropod-like dinosaur Mussaurus from the Late Triassic (Norian stage; about 227 million to 209 million years ago), and the horned dinosaur Protoceratops, from the Late Cretaceous (Campanian stage; about 84 million to 72 million years ago). The authors’ computer-generated evolutionary models also suggest that the scarcity of dinosaur eggs excavated from pre-Cretaceous (older than 145 million years) rocks probably reflects the poor preservation potential of parchment-like eggshells. Furthermore, because soft-shelled eggs are sensitive to both desiccation and physical deformation, it seems reasonable to speculate that they were laid and then buried in moist soil or sand, and relied on external incubation — such as heat derived from decomposing plant matter — rather than a brooding parent.Unlike dinosaurs, mosasaurs (an extinct family of aquatic lizards) and other Mesozoic marine reptiles, such as the dolphin-like ichthyosaurs and long-necked plesiosaurs, are usually considered to have given birth to live young7 — a reproductive strategy termed viviparity. However, this opinion might now be about to change, too. Legendre and colleagues report their discovery of a fossil egg about the size of a football from a latest Cretaceous (about 68 million years ago) nearshore marine setting on what is today Seymour Island, off Antarctica. The authors name their fossil egg specimen Antarcticoolithus, after the Antarctic continent and the ancient Greek words for egg and stone. Antarcticoolithus is among the largest eggs ever recorded (Fig. 1), being rivalled in volume only by those of some non-avian dinosaurs and the extinct Madagascan elephant bird, Aepyornis maximus. Notably however, these other egg types are characterized by thick calcareous shells, whereas Antarcticoolithus has a thin and presumably originally soft covering.Although cautiously pointing out that no embryonic remains were found in the fossil egg, Legendre et al. hypothesize that it might have been laid by a giant marine reptile, and perhaps most feasibly a mosasaur, on the basis of structural similarities to the leathery eggs of lepidosaurs — the group that includes mosasaurs, living lizards, snakes, amphisbaenians (burrowing worm lizards) and the lizard-like tuatara, Sphenodon punctatus. Furthermore, because mosasaurs had streamlined bodies and thus were unable to move on land8, Legendre and colleagues propose that egg laying must have taken place under some depth of water. Nevertheless, although modern viviparous lizards certainly give birth to fully developed young that are surrounded by thin coverings (mainly extraembryonic membranes)9, the few known fossils of pregnant mosasauroids (the group containing mosasaurs and their ancestors) have not been found associated with eggshell debris10. Crucially, mosasaurs were also air breathers; therefore, laying a soft-shelled egg under water would have entailed a considerable risk of drowning for the emerging newborn.Identifying the elusive producer of the Antarcticoolithus egg becomes even more intriguing given the findings of Norell et al., which could implicate some form of dinosaur as the proud parent. Indeed, the total estimated weight of Antarcticoolithus clearly approaches those of the largest non-avian dinosaur and bird eggs, and both these groups have a history of fossil occurrences in Antarctica11. Dinosaur parentage thus at least seems plausible for Antarcticoolithus, which might have been laid on land and then washed out to sea as a discarded eggshell. This could have remained buoyant for some time because of trapped air, before finally sinking to the sea floor, where it was buried in sediment and eventually fossilized. Let us hope that future discoveries of similarly spectacular fossil eggs with intact embryos will solve this thought-provoking enigma.References1. Norell, M. A. et al. Nature 583, 406–410 (2020).2. Legendre, L. J. et al. Nature 583, 411–414 (2020).3. Carpenter, K., Hirsch, K. F. & Horner, J. R. (eds) Dinosaur Eggs and Babies (Cambridge Univ. Press, 1994).4. Norell, M. A., Clark, J. M., Chiappe, L. M. & Dashzeveg, D. Nature 378, 774–776 (1995).5. Schweitzer, M. H., Chiappe, L., Garrido, A. C., Lowenstein, J. M. & Pincus, S. H. Proc. R. Soc. B 272, 775–784 (2005).6. Wiemann, J., Yang, T.-R. & Norell, M. A. Nature 563, 555–558 (2018).7. Blackburn, D. G. & Sidor, C. A. Int. J. Dev. Biol. 58, 935–948 (2014).8. Field, D. J., LeBlanc, A., Gau, A. & Behlke, A. D. Palaeontology 58, 401–407 (2015).9. Blackburn, D. G. Herpetologica 49, 118–132 (1993).10. Caldwell, M. W. & Lee, M. S. Y. Proc. R. Soc. B 268, 2397–2401 (2001).11. Reguero, M. A., Tambussi, C. P., Coria, R. A. & Marenssi, S. A. in Antarctic Palaeoenvironments and Earth-Surface Processes (eds Hambrey, M. J. et al.) 99–116 (Geol. Soc. Lond., 2013).Liu, H., Gao, H., Wu, M., Ma, C., Wu, J., Ye, X., 2020. Distribution characteristics of bacterial communities and hydrocarbon degradation dynamics during the remediation of petroleum-contaminated soil by enhancing moisture content. Microbial Ecology 80, 202-211. are the driver of petroleum hydrocarbon degradation in soil micro-ecological systems. However, the distribution characteristics of microbial communities and hydrocarbon degradation dynamics during the remediation of petroleum-contaminated soil by enhancing moisture content are not clear. In this study, polymerase chain reaction and high-throughput sequencing of soil microbial DNA were applied to investigate the compositions of microorganisms and alpha diversity in the oil-polluted soil, and the hydrocarbon removal also being analyzed using ultrasonic extraction and gravimetric method in a laboratory simulated ex-situ experiment. Results showed the distribution of petroleum hydrocarbon degrading microorganisms in the petroleum-contaminated loessal soil mainly was Proteobacteria phylum (96.26%)—Gamma-proteobacteria class (90.03%)—Pseudomonadales order (89.98%)—Pseudomonadaceae family (89.96%)—Pseudomonas sp. (87.22%). After 15% moisture content treatment, Actinobacteria, Proteobacteria, and Firmicutes still were the predominant phyla, but their relative abundances changed greatly. Also Bacillus sp. and Promicromonospora sp. became the predominant genera. Maintaining 15% moisture content increased the relative abundance of Firmicutes phylum and Bacillus sp. As the moisture-treated time increases, the uniformity and the richness of the soil bacterial community were decreased and increased respectively; the relative abundance of Pseudomonas sp. increased. Petroleum hydrocarbon degradation by enhancing soil moisture accorded with the pseudo-first-order reaction kinetic model (correlation coefficient of 0.81; half-life of 56 weeks). The richness of Firmicutes phylum and Bacillus sp. may be a main reason for promoting the removal of 18% petroleum hydrocarbons responded to 15% moisture treatment. Our results provided some beneficial microbiological information of oil-contaminated soil and will promote the exploration of remediation by changing soil moisture content for increasing petroleum hydrocarbon degradation efficiency.Liu, H., Xu, F., Gao, Y., Pang, Y., Xie, C., Jiang, C., 2020. An integrated LC-MS/MS strategy for quantifying the oxidative-redox metabolome in multiple biological samples. Analytical Chemistry 92, 8810-8818. cellular redox balance plays a significant role in cell fate decisions and in the regulation of responses to various kinds of stress. In this study, we defined a novel concept of the oxidative-redox metabolome, and established a method for the simultaneous quantification of 23 metabolites involved in the oxidative-redox metabolome, covering NAD+ pathway, FAD pathway, GSSG pathway, and ATP pathway by using the AB SCIEX 5500 QTRAP LC/MS/MS system. Corresponding oxidative-redox metabolomics analysis was performed in plasma of humans, hamsters and mice, and hamsters were demonstrated to display a stronger resemblance than mice to humans. The known reductant dithiothreitol (DTT) and oxidant hydrogen peroxide (H2O2) were selected to treat A549 and HeLa cells to validate the current method, showing that DTT moderately increased while H2O2 greatly decreased most analytes. Antibiotic treatment may disturb the oxidative-redox balance in vivo. By comparing the oxidative-redox metabolome in antibiotic-fed hamsters with that of control hamsters, we demonstrated a substantial metabolic disparity between the two, further verifying the applicability and reliability of our method.Liu, J.-F., Lu, Y.-W., Liu, X.-B., Li, B.-G., Sun, Y.-F., Zhou, L., Liu, Y.-F., Yang, S.-Z., Gu, J.-D., Mu, B.-Z., 2020. Dominance of Pseudomonas in bacterial community and inhibition of fumarate addition pathway by injection of nutrients in oil reservoir revealed by functional gene and their transcript analyses. International Biodeterioration & Biodegradation 153, 105039. microbial community composition in subsurface oil reservoirs is responsible for the biogeochemical reactions of hydrocarbon transformation. In this study, the composition, major functions and gene expression activity of the microorganisms in production water from an oil reservoir were analyzed prior to and after injection nutrients using high-throughput 16S rRNA gene sequencing, functional gene and their transcript profiling. Pseudomonas spp. was the dominant bacteria showing a quick increase in the bacterial population. The injection of nutrients lowered the activity of assA-bearing bacteria, but accelerated the activity of methanogens. The results show that the anaerobic hydrocarbon degradation was actively occurring in situ oil reservoir sampled, Smithella was the active anaerobic hydrocarbon degrading bacteria, and Methanoculleus and Methanothrix were the actively dominant methanogens. The present study provides a snapshot of the practical technology with insightful results to support the research, development and utilization of reservoir through biological augmentation.Liu, L., Sotiri, K., Dück, Y., Hilgert, S., Ostrovsky, I., Uzhansky, E., Katsman, R., Katsnelson, B., Bookman, R., Wilkinson, J., Lorke, A., 2020. The control of sediment gas accumulation on spatial distribution of ebullition in Lake Kinneret. Geo-Marine Letters 40, 453-466. freshwater lakes, ebullition is an important pathway for biogenic methane (CH4) to escape from sediment and reach the atmosphere. However, the high spatial and temporal variability of ebullition limits our ability to accurately measure or predict CH4 fluxes from lakes. To explore factors controlling the spatial distribution of ebullition, we investigated free gas accumulation in bottom sediment of Lake Kinneret, Israel. Sediment cores were collected from four sites at different water depth and distance from the shore. Sediment porewater was analyzed for dissolved CH4 concentration, pH, DOC, acetate, and sulfate. Anaerobic CH4 production rates in sediment were determined by incubating sediment samples. For characterizing in situ sediment volumetric gas content, hydroacoustic measurements at various frequencies were conducted at the coring sites and along multiple transects across the lake. A minimum in CH4 production was observed in the upper 30 cm of sediment, which coincided with enriched porewater sulfate. The depth-integrated sediment CH4 production provides a robust estimate for long-term ebullition of CH4 from sediment, while short-term variability was associated with seasonal lake level change. Acoustic measurements revealed the absence of free gas in sediments of the littoral zone and low ebullition rates in the shallow water zones. For the first time, this study reports the role of CH4 production in determining the spatial variability of free gas content in freshwater sediments. The results further demonstrate the importance of sediment gas content in explaining spatial variability of gas ebullition in lakes.Liu, M., Tan, Y., Fang, K., Chen, C., Tang, Z., Liu, X., Yu, Z., 2021. Diverse molecular compositions of dissolved organic matter derived from different composts using ESI FT-ICR MS. Journal of Environmental Sciences 99, 80-89. organic matter (DOM) derived from various composts can promote significant changes of soil properties. However, little is known about the DOM compositions and their similarities and differences at the molecular level. In this study, the molecular compositions of DOM derived from kitchen waste compost (KWC), green waste compost (GWC), manure waste compost (MWC), and sewage sludge compost (SSC) were characterized by electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The molecular formulas were classified into four subcategories: CHO, CHON, CHOS, and CHONS. The KWC, MWC, and SSC DOM represented the highest fraction (35.8%-47.4%) of CHON subcategory, while the GWC DOM represented the highest fraction (68.4%) of CHO subcategory. The GWC DOM was recognized as the nitrogen- and sulfur-deficient compounds that were less saturated, more aromatic, and more oxidized compared with other samples. Further analysis of the oxygen, nitrogen-containing (N-containing), and sulfur-containing (S-containing) functional groups in the four subcategories revealed higher organic molecular complexity. Comparison of the similarities and differences of the four samples revealed 22.8% ubiquitous formulas and 17.4%, 11.1%, 10.7%, and 6.3% unique formulas of GWC, KWC, SSC, and MWC DOM, respectively, suggesting a large proportion of ubiquitous DOM as well as unique, source-specific molecular signatures. The findings presented herein provide new insight into the molecular characterization of DOM derived from various composts and demonstrated the potential role of these different compounds for agricultural utilization.Liu, N., Ogliore, R.C., Vacher, L.G., 2020. NanoSIMS isotopic investigation of xenolithic carbonaceous clasts from the kapoeta howardite. Geochimica et Cosmochimica Acta 283, 243-264. report on the investigation of presolar grains and organic matter (OM) in 14 xenolithic carbonaceous clasts (C-clasts) identified in the Kapoeta howardite based on high-resolution NanoSIMS hydrogen, carbon, nitrogen, and oxygen isotopic imaging data. The 14 C-clasts are ～50–200?μm in size and consist of one CM-like and 13 CI-like clasts, which are classified based on their mineralogies. The clasts from this study are likely sourced from an ice-bearing parent body, either an icy asteroid or a comet, originating from the outer solar system according to the following mineralogical observations: (1) in two CI-like clasts, embayments of magnetite grains between the C-clast and the host howardite point to aqueous alteration occurring on Vesta as a result of melting the ice embedded in the C-clasts; (2) all of the C-clasts, especially the 13 CI-like clasts, likely originated from the same parent body, because (i) the 14 C-clasts are clustered in the thin section, and (ii) the clasts show a much higher ratio of CI-like to CM-like clasts with respect to those reported in the literature. Four presolar silicon carbide (SiC) and two presolar silicate grains were identified in the C-clasts. In addition, all the C-clasts contain moderate bulk D- and 15N-enrichments with the presence of sub-micron to micron-sized D and 15N hotspots, indicating the presence of primitive organic material. Comparison of the abundances and isotopic compositions of presolar grains and OM in these C-clasts with literature data for different samples of primitive extraterrestrial material provides support for (1) the genetic linkage of xenolithic C-clasts to highly aqueously altered but minimally heated carbonaceous chondritic materials and (2) a homogeneous distribution of circumstellar and interstellar materials in the protoplanetary disk. The low amounts of heat experienced by the C-clasts suggest that they arrived at Vesta and/or Vestoids at low speeds after the late heavy bombardment in the inner solar system ～3.5–4.0 Gyr ago.Liu, S.-Q., Sang, S.-X., Hu, Q.-J., Fang, H.-H., 2020. Characteristics of high-rank coal structure parallel and perpendicular to the bedding plane via NMR and X-ray CT. Petroleum Science 17, 925-938. and fractures and their connectivity play a significant role in coalbed methane production. To investigate the growth characteristics and connectivity of pores and fractures in coal parallel and perpendicular to the bedding plane, the pores and fractures of high-rank coal samples collected from the southern Qinshui Basin were measured by low-field nuclear magnetic resonance, X-ray-computed tomography and field emission scanning electron microscopy. Then, the determinants of their connectivity were further discussed. The results show that the high-rank coal samples have similar pore size distributions both parallel and perpendicular to the bedding plane. They primarily contain mesopores (2–50?nm in width), followed by macrospores (>?50?nm in width). The research indicated that the high-rank coal connectivity parallel to the bedding plane is significantly better than that perpendicular to the bedding plane. The connectivity of high-rank coal is mainly determined by throats, and the orientation of the pores and fractures. The two connectivity modes in high-rank coal are “pore connectivity,” in which the throats are mainly pores with a low coordination number, and “microfissure connectivity”, in which the throats are mainly microfissures with a high coordination number.Liu, S., Tang, S., Tan, F., Zhao, C., Li, Y., Wang, S., Huo, T., 2020. Pore structure characteristics and hydrocarbon generation potential of middle Jurassic lacustrine source rocks in the Yuka depression, Qaidam Basin, NW China: Implications from petrographic and organic geochemical analyses. Journal of Natural Gas Science and Engineering 81, 103481. Yuka depression is one of the most important energy production bases in the Qaindam Basin. Although shales in the 7th member of the Dameigou Formation (J2d7) are key members of Middle Jurassic Petroleum System, organic geochemistry and petrography of different rock facies have not been fully analyzed. In this study we evaluate hydrocarbon generation potential of the J2d7 by applying integrated petrographic, geochemical and mineralogical analyses. In addition, pore structure is characterized using field emission scanning electron microscopy (SEM), CO2 and N2 physisorption. Results indicate that mudstone, carbonaceous-mudstone and siltstone have total organic carbon (TOC) values of 2.64%, 5.61% and 0.48%, respectively, as well as variations in the hydrogen index (HI). Kerogen types are mainly Type Ⅲ, with maturity varying from marginally mature to mature. Notably, excess methane adsorption capacities were higher in the carbonaceous-mudstone sample (4.66 cm3/g) than in the mudstone sample (1.78 cm3/g). Primary minerals in the mudstone were quartz and clay; kaolinite, illite and illite/smectite (I/S) were the dominant clay minerals. Clay minerals and TOC content, as well as positive correlations between illite, I/S and mesopore SSA, were factors controlling pore structure development; in contrast, kaolinite contents were negatively correlated with SSA. Liptinite is the dominant maceral composition and a high content of C29 regular sterane in the carbonaceous-mudstones suggests primary higher-plant input, associated with a low gammacerane index (0.28–0.32) and a high pristane/phytane (Pr/Ph) ratio (3.02–3.96). Petrographic and geochemical results indicate an alternating depositional environment across suboxic semi-saline to oxic fresh water changes. Higher-plants were predominant and a small quantity of algae were preserved through in-situ accumulation and migration during shale development; an oxic water column with carbonaceous-mudstone was also present. Although organic matter was marginally mature to mature, the abundance of liptinite (average of 63%) was derived from higher-plants, possibly being the primary materials producing gaseous hydrocarbons.Liu, X., Lu, X., Yu, R., Xue, H., Qi, Z., Cao, Z., Zhang, Z., Liu, T., 2020h. Greenhouse gas emissions from river riparian wetlands: An example from the Inner Mongolia grassland region in China. Biogeosciences Discussions 2020, 1-27. wetlands play a significant role in regulating carbon and nitrogen cycles. Gradual riparian wetland drying is increasingly sensitive to global warming and contributes to climate change. In this study, we analyzed the emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from riparian wetlands in the Xilin River Basin to understand the role of these ecosystems in greenhouse gas (GHG) emissions. Moreover, the impact of the catchment hydrology and soil property variations on GHG emissions over time and space were evaluated. Our results demonstrate that riparian wetlands emit larger amounts of CO2 (335–2790?mg?m?2?h?1 in August and 72–387?mg?m?2?h?1 in October) than CH4 and N2O to the atmosphere due to high plant and soil respiration. The results also reveal clear seasonal variations and spatial patterns along the transects and in the longitudinal direction. N2O emissions showed a spatiotemporal pattern similar to that of CO2 emissions. Near-stream sites were the only sources of CH4 emissions, while the other sites served as sinks for these emissions. Soil moisture content and soil temperature were the essential factors controlling the GHG emissions, and abundant aboveground biomass promoted the CO2, CH4, and N2O emissions. Moreover, compared to different types of grasslands, riparian wetlands were the potential hotspots of GHG emissions in the Inner Mongolian region. Degradation of downstream wetlands has resulted in the loss of the soil carbon pool by approximately 60?%, reducing CO? emissions by approximately 35?%, and shifting the CH4 and N2O emissions from the source to the sink. Our study showed that anthropogenic activities have extensively changed the hydrological characteristics of the riparian wetlands and might accelerate carbon loss, which could further affect the GHG emissions.Liu, X., Wu, L., Kümmel, S., Merbach, I., Lal, R., Richnow, H.H., 2020. Compound-specific isotope analysis and enantiomer fractionation to characterize the transformation of hexachlorocyclohexane isomers in a soil–wheat pot system. Environmental Science & Technology 54, 8690-8698. uptake by plants from soil is one of the first steps for hexachlorocyclohexane (HCH) isomers to enter the food web. However, the HCH transformation associated with the uptake process is still not well understood. Therefore, a soil–wheat pot experiment was conducted to characterize the HCH transformation during wheat growth using compound-specific isotope analysis (CSIA) and enantiomer fractionation. The results showed that the δ13C and δ37Cl values of β-HCH remained stable in soil and wheat, revealing no transformation. In contrast, an increase of δ13C and δ37Cl values of α-HCH indicated its transformation in soil and wheat. A shift of the enantiomer fraction (EF) (?) from 0.50 to 0.35 in soil at the jointing stage and 0.35 to 0.57 at the harvest stage suggested that the preferential transformation of enantiomers varied at different growth stages. Based on the dual element isotope analysis, the transformation mechanism in the soil–wheat system was different from that in wheat in hydroponic systems. The high abundance of HCH degraders, Sphingomonas sp. and Novosphingobium sp., was detected in the α-HCH-treated rhizosphere soil, supporting the potential for biotransformation. The application of CSIA and EF allows characterizing the transformation of organic pollutants such as HCHs in the complex soil–plant systems.Liu, X., Zhang, W., Qu, Z., Guo, T., Sun, Y., Rabiei, M., Cao, Q., 2020. Feasibility evaluation of hydraulic fracturing in hydrate-bearing sediments based on analytic hierarchy process-entropy method (AHP-EM). Journal of Natural Gas Science and Engineering 81, 103434. gas hydrate is an attractive potential as alternative energy source. The initial studies of natural gas hydrate production test have shown that the hydrate productivity via conventional depressurization is still far to reach the commercial level, hence, hydraulic fracturing has been proposed to stimulate the hydrated formation to enhance production. However, the buried depth of hydrate-bearing sediments is generally shallow, and the cementation of sediments is weak. Whether the hydrate-bearing sediments has adequate and commercially viable fracability is a question yet to be answered. In this study, a novel feasibility evaluation model of hydraulic fracturing in hydrate-bearing sediments is developed based on analytic hierarchy process-entropy method. The fracability index is proposed to evaluate the fracability of hydrate-bearing sediments. Representative samples were built based on the physical and mechanical characteristics of Alaska permafrost, and hydraulic fracturing experiments were carried out to evaluate the feasibility of hydraulic fracturing as a stimulation technique. The results showed that the hydrate-bearing sediments with fracability index >0.72 can form fractures under different fracturing fluid viscosity ratio. For hydrate-bearing sediments with fracability index <0.39, when the fracturing fluid viscosity ratio is 1, no fracture network is formed during hydraulic fracturing. However, when the fracturing fluid viscosity ratio is increased to more than 120, fractures may develop. For the hydrate-bearing sediments with fracability index between 0.39 and 0.72, the results are not promising when fracturing fluid viscosity ratio is 1, however, when fracturing fluid viscosity ratio is more than 120, fractures observed to grow. In general, the results indicate that the samples with high fracability index are sweet spots in hydrate sediments in terms of fracability. At low fracability index values, the viscosity of fracturing fluid has a key role in fracability, where increasing the viscosity will result in higher fracability index.Longo, L.M., Despotovi?, D., Weil-Ktorza, O., Walker, M.J., Jab?ońska, J., Fridmann-Sirkis, Y., Varani, G., Metanis, N., Tawfik, D.S., 2020. Primordial emergence of a nucleic acid-binding protein via phase separation and statistical ornithine-to-arginine conversion. Proceedings of the National Academy of Sciences 117, 15731-15739.: The first proteins emerged some 4 billion y ago, and understanding how they came about is a daunting challenge. Further complicating matters, the rules of protein structure and function derived from modern proteins may be irrelevant to their earliest ancestors. We report an integrated approach in which protein sequence, structure, and function are considered. We show that a simple function (phase separation) may have served as the basis for a complex function (specific double-stranded DNA binding), and that disordered polypeptides can give rise to structured, well-packed domains. Finally, we demonstrate that functional proteins may arise from short and simple sequences that include ornithine, an amino acid likely present in early proteins yet absent in modern proteins.Abstract: De novo emergence demands a transition from disordered polypeptides into structured proteins with well-defined functions. However, can polypeptides confer functions of evolutionary relevance, and how might such polypeptides evolve into modern proteins? The earliest proteins present an even greater challenge, as they were likely based on abiotic, spontaneously synthesized amino acids. Here we asked whether a primordial function, such as nucleic acid binding, could emerge with ornithine, a basic amino acid that forms abiotically yet is absent in modern-day proteins. We combined ancestral sequence reconstruction and empiric deconstruction to unravel a gradual evolutionary trajectory leading from a polypeptide to a ubiquitous nucleic acid-binding protein. Intermediates along this trajectory comprise sequence-duplicated functional proteins built from 10 amino acid types, with ornithine as the only basic amino acid. Ornithine side chains were further modified into arginine by an abiotic chemical reaction, improving both structure and function. Along this trajectory, function evolved from phase separation with RNA (coacervates) to avid and specific double-stranded DNA binding. Our results suggest that phase-separating polypeptides may have been an evolutionary resource for the emergence of early proteins, and that ornithine, together with its postsynthesis modification to arginine, could have been the earliest basic amino acids.Lu, M., Connell, L.D., Pan, Z., 2020. Wetting fluid behaviour with phase transition in geological nanopores: Liquid film, capillary condensation and evaporative flow. Journal of Petroleum Science and Engineering 195, 107570. behaviour in nanoscale pores may significantly deviate from that in its bulk state, because pore-wall effects may have critical influences on fluid properties such that its behaviour becomes surface-controlled. Geologically, study of fluid flow with phase transition (condensation/evaporation) in nanoscale pores is of considerable significance in practice, as understandings of the relevant mechanisms may greatly help optimise operation conditions in field applications. Typical examples include geological disposal of contaminated wastes and recovery of resources from unconventional gas and oil reservoirs. In this text, we present a study to systematically investigate how the fluid behaviour, such as the liquid film formed on a pore-wall, the condensation/evaporation of the fluid and the evaporative flow profile in the pore, depends on the molecular/electrical surface forces and the pore-wall-curvature. Towards this we first formulated a set of extended phase equilibrium relationships following a rigorous thermodynamic procedure in which the relevant pore-wall effects are included. Then, a set of new evaporative flow equations was developed, which improves the original Mahadevan model by taking into account the pore-wall effects engaged. Several laboratory tests published in literature were employed to compare the present model with the Mahadevan model. With the results obtained we discussed the pertinent pore-wall effects on the evaporation behaviour of the water, and it was shown that for the evaporative flow process concerned, these effects are significantly important and considerable deviations would be generated without consideration of them.Lu, Q., He, D., Pang, Y., Zhang, Y., He, C., Wang, Y., Zhang, H., Shi, Q., Sun, Y., 2020. Processing of dissolved organic matter from surface waters to sediment pore waters in a temperate coastal wetland. Science of The Total Environment 742, 140491. wetlands are active transitional ecotones between land and ocean, and are considered as hot spots of organic matter processing within the global carbon cycle, which dissolved organic matter (DOM) plays a critical role. In this study, combined use of ultrahigh-resolution mass spectrometry (FT-ICR MS) and complementary optical techniques was conducted to assess the detailed molecular composition of DOM in the temperate Liaohe coastal wetland (LCW), NE China in respect to the differences in DOM composition from surface water to sediment pore water. Significant positive correlations between salinity and dissolved organic carbon (DOC) concentrations were observed in both surface waters and pore waters. Pore water DOM is generally characterized by lower protein-like fluorescence and biological index, but higher humification and humic-like fluorescent components than those in surface water DOM. Corresponding to the optical properties, FT-ICR MS measurements show that pore water DOM has higher proportions of heteroatoms, aromaticity index, O/C ratios, unsaturated aliphatics, and peptides, but lower average H/C ratios compared to surface water DOM across locations with different marsh plant species (rice (Oryza sativa), reed (Phragmites australis), Seablite (Suaeda Salsa)) and salinity (0.5 to 51.5 psu). The results suggest that selective preservation for polyphenols, lignin degradation intermediates (highly unsaturated compounds), and microbial resynthesis of heteroatomic compounds are involved in the processing of DOM from surface water to pore water, leading to the formation of higher molecular weight and sulfur-containing molecules. The abundant CHOS compounds could be related to the early diagenetic sulfurization of DOM in sediments. Our unique data set should provide new clues for a comprehensive understanding of the molecular dynamics of DOM in coastal wetlands.Lu, Y.-q., Jiang, Y.-l., Wang, W., Du, J.-f., Liu, J.-d., 2020. Coupling relationship between reservoir diagenesis and hydrocarbon accumulation in Lower Cretaceous Yingcheng Formation of Dongling, Changling fault depression, Songliao Basin, Northeast China. China Geology 3, 247-261. The Lower Cretaceous Yingcheng Formation in the southern Songliao Basin is the typical tight oil sandstone in China. In order to better predict the petrophysical properties of the tight sandstone reservoirs in the Lower Cretaceous Yingcheng Formation, Songliao Basin, Northeast China, the diagenesis and porosity evolution was investigated using a suite of petrographic and geochemical techniques including thin section analysis, scanning electron microscopy, mercury intrusion and fluid inclusion analysis, on a set of selected tight sandstone samples. Combined with the histories of burial evolution, organic matter thermal evolution and hydrocarbon charge, the matching relationship between reservoir porosity evolution and hydrocarbon accumulation history is analyzed. The result showed that the tight sandstone reservoirs characterized of being controlled by deposition, predominated by compaction, improved by dissolution and enhanced by cementation. The hydrocarbon accumulation period was investigated using a suite of hydrocarbon generation and expulsion history, microfluorescence determination and temperature measurement technology. According to the homogenization temperature of the inclusions and the history of burial evolution, Yingcheng Formation has mainly two phases hydrocarbon accumulation. The first phase of oil and gas is charged before the reservoir is tightened, the oil and gas generated by Shahezi source rocks enter the sand body of Yingcheng Formation, influenced by the carrying capability of sand conducting layer, oil and gas is mainly conducted by the better properties and higher connectivity sand body and enriched in the east, which belongs to the type of densification after hydrocarbon accumulation. The second phase of oil and gas charge after densification, which belongs to the type of densification before the hydrocarbon accumulation.Luo, Q., Gu, L., Shan, Y., Wang, H., Sun, L., 2020. Distribution, source apportionment, and health risk assessment of polycyclic aromatic hydrocarbons in urban soils from Shenyang, China. Environmental Geochemistry and Health 42, 1817-1832. total of 74 urban topsoil samples were collected from the central area of Shenyang, China. The concentration, distribution, source, and health risk of 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed. The 16 USEPA priority PAHs were detected in all soil samples. The total concentrations of PAHs ranged from 283 to 21,821?ng/g dry weight (dw), with a mean value of 2370?ng/g and median value of 1427?ng/g. The benzo[a]pyrene toxicity equivalent (BaPeq) concentrations ranged from 6.03 to 2403?ng/g dw, with a mean value of 308?ng/g and median value of 185?ng/g. High molecular weight PAHs were the predominant components. The spatial distribution revealed that soil PAH concentrations within the Two Ring Road were high, but low in the south of Hun River. Compared with other urban soils, the pollution of PAHs in urban soils of Shenyang was at a moderate level, but increased rapidly compared with previous years, especially fluoranthene. Diagnostic ratios of PAHs and positive matrix factorization model all suggested that PAHs in urban soils of Shenyang were dominantly from pyrogenic origins. The health risk assessment indicated that children had the highest total carcinogenic risk, followed by adolescents and adults. The differences between gender groups for the same age group were insignificant. Ingestion was the dominant exposure pathway, followed by dermal contact and inhalation. The total lifetime carcinogenic risks at all sampling sites were lower than the highest acceptable risk (10?4), and those of Eastern, Central, and Western Shenyang were higher than those of Northern and Southern Shenyang.Lv, W., Guo, L., Zheng, F., Wang, Q., Wang, W., Cui, L., Ouyang, Y., Liu, X., Li, E., Shi, X., Xu, G., 2020. Alternate reversed-phase and hydrophilic interaction liquid chromatography coupled with mass spectrometry for broad coverage in metabolomics analysis. Journal of Chromatography B 1152, 122266. of the greatly different physicochemical properties of metabolites, comprehensive metabolite profiling analysis has always been a challenging task. Reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC) have been used to the analysis of nonpolar metabolites and polar metabolites, respectively. In this work, an alternate HILIC/RPLC-mass spectrometry (MS) approach was developed for the comprehensive and high-throughput analysis of polar and nonpolar metabolites. HILIC and RPLC are respectively performed on two ultra-high performance LC (UHPLC) systems, and coupled to one mass spectrometer to acquire the data. When HILIC gradient elution is running RPLC is in a washing and equilibration state, and vice versa. As a result, the total analysis time was reduced by about one third to 25.4 min. Two hundred and eight representative standards including at least twelve types of commonly met metabolites, SRM 1950 plasma, serum, urine and liver tissue samples were used to test the established alternate HILIC/RPLC-MS method. The results demonstrated that the method possessed high metabolite coverage. The developed method was validated to have good linearity and repeatability. As an example of application, 61 significantly changed metabolites in the colon cancer tissues were defined by this established method.Ma, D., Wu, J., Yang, P., Zhu, M., 2020. Coupled manganese redox cycling and organic carbon degradation on mineral surfaces. Environmental Science & Technology 54, 8801-8810., natural organic matter (NOM), and divalent manganese (Mn(II)) often coexist in suboxic/oxic environment. Multiple adsorption and oxidation processes occur in this ternary system, which are coupled to affect the fate of both OM and Mn therein and alter their chemical reactivity toward metals and other pollutants. However, the details about the coupling are poorly known although much has been gained for the binary systems. We determined the mutual influence of surface-catalyzed Mn(II) oxidation and humic acid (HA) adsorption and oxidation in a Fe(III) oxide (goethite)-HA-Mn(II) system at pH 5–8. The presence of Mn(II) substantially increased HA adsorption whereas HA greatly impaired the extent and rate of Mn(II) oxidation by O2 on goethite surfaces. The impacts were more pronounced at higher pH. Mn(II) oxidation produced β-MnOOH, γ-MnOOH, and Mn3O4 which in turn oxidized HA, producing small organic acids. The presence of HA markedly altered the composition of Mn(II) oxidation products by inhibiting the formation of β-MnOOH while favoring the production of γ-MnOOH and Mn(II) adsorbed on the HA-mineral assemblage. Nonconducting γ-Al2O3 exhibited similar but weaker effects than semiconducting goethite in the above processes. Our results suggest that similar to Mn-oxidizing microorganisms, mineral surfaces can drive the coupling of the Mn redox cycle with NOM oxidative degradation under suboxic/oxic and circumneutral/alkaline conditions.Ma, X., Sun, Y., Guo, W., Jia, R., Li, B., 2020. Effects of irreducible fluid saturation and gas entry pressure on gas production from hydrate-bearing clayey silt sediments by depressurization. Geofluids 2020, 9382058. hydrates in the Shenhu area are mainly hosted in clayey silt sediments, which have the relatively high irreducible fluid saturation and gas entry pressure. And then, they will have an impact on gas production from hydrate-bearing clayey silt sediments, which was evaluated by the numerical simulations of SH2 site in Shenhu area in this paper. The results showed that, with the increase in irreducible water saturation and irreducible gas saturation, the amount of water production and gas production was obviously reduced. When the irreducible water saturation increased from 0.10 to 0.50, the cumulative CH4 production volume decreased from 1668799?m3 to 1536262?m3, and the cumulative water production volume dropped from 620304?m3 to 564797?m3, respectively. When the irreducible gas saturation increased from 0.01 to 0.05, the cumulative CH4 production volume dropped from 1812522?m3 to 1622121?m3, and the cumulative water production volume dropped from 672088?m3 to 600617?m3, respectively. In addition, the capillary pressure increased obviously with the increase in gas entry pressure, but the effect on gas production was small and the effect on water production could be negligible. In conclusion, irreducible water and gas saturation had an important effect on the gas production from gas hydrate, whereas the effects of gas entry pressure could be ignored.MacDonald, J.G., Rodriguez, K., Quirk, S., 2020. An oxygen delivery polymer enhances seed germination in a martian-like environment. Astrobiology 20, 846-863. to the success of establishing a sustainable human presence on Mars is the ability to economically grow crop plants. Several environmental factors make it difficult to fully rely on local resources for agriculture. These include nutrient sparse regolith, low and fluctuating temperatures, a high amount of ultraviolet radiation, and water trapped locally in the form of ice or metal oxides. While the 96% CO2 martian atmosphere is ideal to support photosynthesis, high CO2 concentrations inhibit germination. An added difficulty is the fact that a vast majority of crop plants require oxygen for germination. Here, we report the production of a polymer-based oxygen delivery system that supports the germination and growth of cress seeds (Lepidium sativum) in a martian regolith simulant under a martian atmosphere at 101?kPa. The oxygen-donating system is based on a low-density lightly cross-linked polyacrylate that is foamed and converted into a dry powder. It is lightweight, added in low amounts to regolith simulant, and efficiently donates enough oxygen throughout the volume of hydrated regolith simulant to fully support seed germination and plant growth. Germination rates, plant development, and plant mass are nearly identical for L. sativum grown in 100% CO2 in the presence of the oxygen-donating lightly cross-linked polyacrylate compared with plants grown in air. The polymer system also serves to protect root structures and better anchors plants in the regolith simulant. Macey, M.C., Fox-Powell, M., Ramkissoon, N.K., Stephens, B.P., Barton, T., Schwenzer, S.P., Pearson, V.K., Cousins, C.R., Olsson-Francis, K., 2020. The identification of sulfide oxidation as a?potential metabolism driving primary production on late Noachian Mars. Scientific Reports 10, 10941. transition of the martian climate from the wet Noachian era to the dry Hesperian (4.1–3.0 Gya) likely resulted in saline surface waters that were rich in sulfur species. Terrestrial analogue environments that possess a similar chemistry to these proposed waters can be used to develop an understanding of the diversity of microorganisms that could have persisted on Mars under such conditions. Here, we report on the chemistry and microbial community of the highly reducing sediment of Colour Peak springs, a sulfidic and saline spring system located within the Canadian High Arctic. DNA and cDNA 16S rRNA gene profiling demonstrated that the microbial community was dominated by sulfur oxidising bacteria, suggesting that primary production in the sediment was driven by chemolithoautotrophic sulfur oxidation. It is possible that the sulfur oxidising bacteria also supported the persistence of the additional taxa. Gibbs energy values calculated for the brines, based on the chemistry of Gale crater, suggested that the oxidation of reduced sulfur species was an energetically viable metabolism for life on early Mars.Maloney, K.M., Boag, T.H., Facciol, A.J., Gibson, B.M., Cribb, A., Koester, B.E., Kenchington, C.G., Racicot, R.A., Darroch, S.A.F., Laflamme, M., 2020. Paleoenvironmental analysis of Ernietta-bearing Ediacaran deposits in southern Namibia. Palaeogeography, Palaeoclimatology, Palaeoecology 556, 109884. fossils from the Nama Group (Kuibis Subgroup) of southern Namibia have a long history of scientific scrutiny, however many of the fossil localities still require investigation from a sedimentary facies and sequence stratigraphic standpoint. Detailed sedimentary analyses utilizing chemostratigraphy and facies-based approaches resulted in five proposed facies and two paleoenvironmental settings that allow for interpretation of the fossiliferous sections as a nearshore to a protected shallow marine paleoenvironment. The classic Ediacaran taxon Ernietta was restricted to the Kliphoek Member of the Nama Group, which limits the stratigraphic range of these organisms to the younger depositional sequence of the Kuibis Subgroup. The paleoenvironment has been interpreted as a mixed carbonate-siliciclastic, protected shallow marine environment at Farm Hansburg, suggesting that these organisms thrived in environments with medium to high flow velocities and periodic clastic sediment supply. Studies that utilize detailed paleoenvironmental reconstructions may aid in constraining phylogenetic affinities of the Ediacara biota by placing reasonable bounds on the local habitat.Manheim, J.M., Milton, J.R., Zhang, Y., Kentt?maa, H.I., 2020. Fragmentation of saturated hydrocarbons upon atmospheric pressure chemical ionization is caused by proton-transfer reactions. Analytical Chemistry 92, 8883-8892. characterization of complex mixtures of large saturated hydrocarbons is critically important for numerous fields, including petroleomics and renewable transportation fuels, but difficult to achieve. Atmospheric pressure chemical ionization (APCI) mass spectrometry has shown some promise in the analysis of saturated hydrocarbons. However, APCI causes extensive fragmentation to these compounds, which impedes its effectiveness. To prevent this fragmentation, its causes were examined via gas-phase ion–molecule reactions in vacuum in a linear quadrupole ion trap mass spectrometer. The results demonstrate that the mechanism proposed previously for ionization of saturated hydrocarbons upon APCI, hydride abstraction by carbocation reagent ions, is not correct. Instead, the fragmentation is caused by ionization of saturated hydrocarbons via exothermic proton-transfer reactions involving highly acidic, protonated atmospheric molecules, such as nitrogen and water. Accordingly, the extent of fragmentation was found to correlate with the proton affinities of the atmospheric molecules studied. Remarkably, controlled experiments involving isolated atmospheric ions and neat saturated hydrocarbons in vacuum yielded almost identical mass spectra as APCI involving atmospheric pressure conditions, the presence of many different chemicals, and an electrical discharge. In order to prevent or reduce the extent of fragmentation of saturated hydrocarbons upon APCI, and therefore enable accurate mass spectrometric characterization of complex mixtures of saturated hydrocarbons, the ion source should be purged of air to remove nitrogen and water and fill it with an inert gas with a substantially lower proton affinity.Marcinek, S., Santinelli, C., Cindri?, A.-M., Evangelista, V., Gonnelli, M., Layglon, N., Mounier, S., Lenoble, V., Omanovi?, D., 2020. Dissolved organic matter dynamics in the pristine Krka River estuary (Croatia). Marine Chemistry 225, 103848. karstic Krka River is characterized by having lower dissolved organic carbon (DOC) concentrations (~30 μM) than coastal seawater (~60 μM). This peculiarity, together with the pristine nature of this area, makes the Krka River estuary a natural laboratory where it is possible to discriminate among the different dissolved organic matter (DOM) sources (riverine, marine and produced in-situ) and to study the main processes of DOM production and removal. The hypothesis behind this work is that in winter, due to the high discharge of the river, most of the DOM has a terrestrial signature, whereas in summer autochthonous DOM compose the main fraction of the DOM pool because of the reduced discharge, the high temperature and primary production. Our data shows that DOM in the river mainly consists of terrestrial molecules, as suggested by the high chromophoric content and low spectral slope (S275–295) values, as well by the predominance of humic-like substances. DOM in the seawater features the concentration and optical properties of the “typical” marine DOM from open sea waters. In summer, low riverine discharge and high temperature promote the intense biological activity, with an increase in DOC concentrations of up to 148 μM, resulting in a non-conservative behavior of DOM in the estuary. The high stratification combined with a decoupling between production and removal processes can explain the observed DOM accumulation. In the bottom layer DOM was released and quickly removed when oxygen was available, whereas in hypoxic waters the production of DOC, chromophoric DOM (CDOM) and fluorescent DOM (FDOM) was linearly related to oxygen consumption. Our work highlights the need of further studies combining chemical and biological information in order to gain new insights into the main processes responsible for DOM dynamics in this system.Mari?, N., ?trba?ki, J., Mrazovac Kurili?, S., Be?koski, V.P., Niki?, Z., Ignjatovi?, S., Malba?i?, J., 2020. Hydrochemistry of groundwater contaminated by petroleum hydrocarbons: the impact of biodegradation (Vitanovac, Serbia). Environmental Geochemistry and Health 42, 1921-1935. contamination by petroleum hydrocarbons leads to measurable changes of groundwater hydrochemistry, primarily due to the microbiological activity. This study analyzes this phenomenon at an historical kerosene-contaminated site in Vitanovac (central Serbia). Due to the long-term hydrocarbon contamination and exposure to aerobic and anaerobic biodegradation mechanisms, the lowest concentrations of O2, NO3?, and SO42? (electron acceptors) and the highest concentrations of Mn and Fe (products of microbial metabolic activity) overlap. The terminal redox-accepting processes in groundwater ranged from oxygen reduction to sulfate reduction. The most anoxic processes were registered in piezometers closest to the source of contamination, as was also confirmed by the redox potential (Eh) measurements. High electrical conductivity values and the highest TOC, SiO2, and Al concentrations also overlap in the contaminated zone close to the source of contamination. Scanning electron microscopy study of quartz grains from the zone undergoing the impact of biodegradation confirmed the occurrence of weathering microscale processes on mineral surfaces. Taking all these factors together, it seems reasonable to assume that microbiological activity has caused the enhanced weathering of silicate minerals.Marín, P., Yang, Z., Xia, Y., Ordó?ez, S., 2020. Concentration of unconventional methane resources using microporous membranes: Process assessment and scale-up. Journal of Natural Gas Science and Engineering 81, 103420. methane resources are usually diluted in air, which prevents their use as feedstock in chemical or thermal processes. Some of them (e.g. coal mine ventilation air or diluted landfill biogas) are emitted directly to the atmosphere without harnessing, increasing the contribution of methane to global warming. Gas permeation membranes offer an alternative for the concentration of these methane resources, increasing considerably their harnessing possibilities. Microporous materials, such as carbon molecular sieve, zeolite or metal organic frameworks, have emerged as alternative to polymeric materials for the preparation of these membranes.The present work is based on simulations of the separation of methane and nitrogen mixtures, using SAPO-34 and carbon molecular sieve membranes. Mass transfer has been modelled in two scales: the membrane material (modelled using the Maxwell-Stefan multicomponent surface diffusion model) and the membrane module (based on the plug flow model). A sensitivity analysis of the influence of the main operating variables on the membrane performance has revealed that the most important ones are transmembrane pressure difference, methane feed concentration and membrane loading. It has been found that SAPO-34 membranes are more suited to concentrate methane in lean mixtures, while the carbon membrane perform better with rich mixtures.The membrane process has been scaled-up for a feed gas flow rate of 1000 m3/h n.t.p. with target methane recovery of 70% for two cases: lean (1%) and rich (50%) methane feed mixtures.Martano, G., Leone, M., D’Oro, P., Matafora, V., Cattaneo, A., Masseroli, M., Bachi, A., 2020. Smfinder: Small molecules finder for metabolomics and lipidomics analysis. Analytical Chemistry 92, 8874-8882. and lipidomics studies are becoming increasingly popular but available tools for automated data analysis are still limited. The major issue in untargeted metabolomics is linked to the lack of efficient ranking methods allowing accurate identification of metabolites. Herein, we provide a user-friendly open-source software, named SMfinder, for the robust identification and quantification of small molecules. The software introduces an MS2 false discovery rate approach, which is based on single spectral permutation and increases identification accuracy. SMfinder can be efficiently applied to shotgun and targeted analysis in metabolomics and lipidomics without requiring extensive in-house acquisition of standards as it provides accurate identification by using available MS2 libraries in instrument independent manner. The software, downloadable at ifom.eu/SMfinder, is suitable for untargeted, targeted, and flux analysis.Matsumoto, H., Kuroda, J., Coccioni, R., Frontalini, F., Sakai, S., Ogawa, N.O., Ohkouchi, N., 2020. Marine Os isotopic evidence for multiple volcanic episodes during Cretaceous Oceanic Anoxic Event 1b. Scientific Reports 10, 12601. Aptian–Albian boundary is marked by one of the major oceanic perturbations during the Cretaceous, called Oceanic Anoxic Event (OAE) 1b. Extensive volcanic episodes at the Southern Kerguelen Plateau has been suggested as the trigger of OAE1b, but compelling evidence remains lacking. Here, we reconstructed the temporal variations of marine Os isotopic ratios across the Aptian–Albian boundary in the Tethyan and Pacific pelagic sedimentary records to elucidate the causal links between OAE1b, the biotic turnover, and volcanic episodes. Our new Os isotopic records show two negative spikes that correlate with a period of planktonic foraminiferal turnover across the Aptian–Albian boundary during OAE1b and suggest multiple submarine volcanic events. By comparing our Os isotopic profile with carbon isotopic compositions of carbonate, CaCO3 content, and the relative abundances of agglutinated foraminifera, we conclude that ocean acidification caused by the massive release of CO2 through extensive volcanic episodes could have promoted the major planktonic foraminiferal turnover during OAE1b.Matthews, E., Johnson, M.S., Genovese, V., Du, J., Bastviken, D., 2020. Methane emission from high latitude lakes: methane-centric lake classification and satellite-driven annual cycle of emissions. Scientific Reports 10, 12465. (CH4) is emitted from lakes by several processes: bubbles released from bottom sediments that reach the atmosphere (ebullition); spring release of CH4 trapped in bubbles in and under the ice during fall freeze (bubble release), and diffusion of CH4 from sediments to the surface. Each of these emission routes is highly variable over space and time, and episodic in the extreme, making reliable measurements difficult to carry out. However, lakes are receiving increasing interest for their important contribution to global CH4 emissions. Their area, distribution and emissions respond to interannual and longer-term climate fluctuations and close to half the world’s lake area is in high northern latitudes that are experiencing rapidly-warming temperatures and lengthening thaw periods. We report on a new spatially-explicit data set of lakes >?50°N, classified with methane-relevant criteria. The seasonality of daily CH4 fluxes is driven with satellite observations of thaw timing and duration. We found that observed thaw seasons are 10–30% shorter than those assumed in previous studies. The area of lakes is 1,095?×?103 km2 and total CH4 emission is 13.8–17.7 Tg CH4 year?1: 11.2–14.4 Tg via diffusion and ebullition and 2.6–3.3 Tg from spring release of CH4 stored in bubbles in winter lake ice. This novel suite of data and methodologies provides a unique framework to model CH4 emission from lakes under current, past and future climates.Mau, S., Tu, T.-H., Becker, M., dos Santos Ferreira, C., Chen, J.-N., Lin, L.-H., Wang, P.-L., Lin, S., Bohrmann, G., 2020. Methane seeps and independent methane plumes in the South China Sea offshore Taiwan. Frontiers in Marine Science 7, 543. doi: 10.3389/fmars.2020.00543. the northern South China Sea (SCS) we explored methane dynamics in the water column during SONNE-cruise SO266 in October/November 2018. Two depth zones contained elevated methane concentrations: the upper 400 m (<10 nM) and near gas seeps at the seafloor (up to 2100 nM). Seeps occurred at Four Way Closure Ridge (FWCR) at the active continental margin as well as at Southern Summit Formosa Ridge (SSFR) at the passive continental margin. In the upper ocean, methane dynamics correlated with (1) temperature, (2) water masses, and (3) suspended matter. In the first case, elevated methane concentrations and aerobic methane oxidation rates (MOxs) occurred in water with temperatures > 10°C and > 20°C, respectively. Both 16S rRNA gene and pmoA amplicon analyses revealed distinct microbial and methanotrophic communities in water with temperature of 27°C, ～10°C, and 3°C. Second, we found elevated methane concentrations in 200–400 m in the FWCR-region whereas increased methane concentrations occurred in the uppermost 100 m above SSFR. The deeper plume above FWCR might be due to an intrusion of the Kuroshio water mass into SCS keeping the methane from being aerobically oxidized in the warm surface water and vented to the atmosphere. Finally, all peak methane concentrations occurred in water depth, with rather low backscatter, i.e., in water depth with less suspended matter. At the seafloor, ocean currents and long-term seepage appeared to control methane dynamics. We derived methane fluxes of 0.08–0.12 mmol m–2 d–1 from a 4.5 km2 area at FWCR and of 3.0–79.9 mmol m–2 d–1 from a 0.01 km2 area at SSFR. Repetitive sampling of the area at SSFR indicated that changing directions of ocean currents possibly affected methane concentrations and thus flux. In contrast to these seepage sites with distinct methane plumes, retrieval of drilling equipment produced no methane plume. Even gas emission triggered by seafloor drilling did not supply measureable methane concentrations after 3 h, but caused an increase in methanotrophic activity as determined by rate measurements and molecular-biological analyses. Apparently, only long-term seepage can generate methane anomalies in the ocean.Maufrangeas, A., Leleu, S., Loisy, C., Roperch, P., Jolley, D., Vinciguerra, C., Nguyen-Thuyet, O., 2020. Stratigraphy of the Paleocene continental sedimentary succession of the northern Pyrenean basin (Corbières, southern France) using δ13C isotopes. Journal of the Geological Society 177, 752. successions are often poorly constrained stratigraphically due to a lack of robust biostratigraphic markers. This study provides the first dataset of δ13Corg together with magnetostratigraphic and biostratigraphic data from a thick continental-dominated succession at Lairière (northern Pyrenees, France). This section encompasses the latest Cretaceous up to the Paleocene–Eocene Thermal Maximum interval and is characterized by fluvial deposits, occasionally intercalated with continental carbonates, lacustrine deltaic deposits and shallow marine sediments. This work identifies δ13Corg events and assigns them to global δ13C geochemical events defined in Pyrenean and Tethyan marine successions, in which the stage boundaries are well calibrated. As the isotopic measurements are performed on dispersed organic matter in sedimentary rocks with a low organic content, we propose that analyses of the signal should take into consideration the depositional environment because variations in the organic matter content might affect the signal. We establish a high-resolution chronostratigraphy in terrestrial Paleocene deposits in the NE Pyrenean zone, recognize a late Selandian interval and define the Paleocene–Eocene Thermal Maximum event.Maurice, M., Tosi, N., Schwinger, S., Breuer, D., Kleine, T., 2020. A long-lived magma ocean on a young Moon. Science Advances 6, eaba8949. giant impact onto Earth led to the formation of the Moon, resulted in a lunar magma ocean (LMO), and initiated the last event of core segregation on Earth. However, the timing and temporal link of these events remain uncertain. Here, we demonstrate that the low thermal conductivity of the lunar crust combined with heat extraction by partial melting of deep cumulates undergoing convection results in an LMO solidification time scale of 150 to 200 million years. Combining this result with a crystallization model of the LMO and with the ages and isotopic compositions of lunar samples indicates that the Moon formed 4.425 ± 0.025 billion years ago. This age is in remarkable agreement with the U-Pb age of Earth, demonstrating that the U-Pb age dates the final segregation of Earth’s core.May, J.C., Knochenmuss, R., Fjeldsted, J.C., McLean, J.A., 2020. Resolution of isomeric mixtures in ion mobility using a combined demultiplexing and peak deconvolution technique. Analytical Chemistry 94, 9482-9492. combined data acquisition and data processing strategy for improving the sensitivity and resolution of ion mobility measurements is described. This strategy is implemented on a commercially available drift tube ion mobility-mass spectrometry (IM-MS) instrument and utilizes both an existing ion multiplexing strategy to achieve up to an 8-fold gain in ion signal and a new postacquisition data reconstruction technique, termed “high resolution demultiplexing” (HRdm), to improve resolution in the ion mobility dimension. A series of isomeric mixtures were qualitatively investigated with HRdm, including biologically relevant lipids and carbohydrates, which were successfully resolved by HRdm, including two monosaccharide regioisomers which differed in drift time by only 0.8%. For a complex trisaccharide isomer mixture, HRdm was able to resolve 5 out of 6 components. An analysis of two-peak resolution (Rpp) and peak-to-peak separation (ΔP) indicated that HRdm performs with an effective resolving power (Rp) of between 180 to 250 for the highest deconvolution settings. Overall analysis times and drift time measurement precision were found to be unaffected between standard and HRdm processed data sets, which allowed statistically identical collision cross section values to be directly determined from all ion mobility spectra.Mays, C., Vajda, V., Frank, T.D., Fielding, C.R., Nicoll, R.S., Tevyaw, A.P., McLoughlin, S., 2020. Refined Permian–Triassic floristic timeline reveals early collapse and delayed recovery of south polar terrestrial ecosystems. GSA Bulletin 132, 1489-1513. collapse of late Permian (Lopingian) Gondwanan floras, characterized by the extinction of glossopterid gymnosperms, heralded the end of one of the most enduring and extensive biomes in Earth’s history. The Sydney Basin, Australia, hosts a near-continuous, age-constrained succession of high southern paleolatitude (～65–75°S) terrestrial strata spanning the end-Permian extinction (EPE) interval. Sedimentological, stable carbon isotopic, palynological, and macrofloral data were collected from two cored coal-exploration wells and correlated. Six palynostratigraphic zones, supported by ordination analyses, were identified within the uppermost Permian to Lower Triassic succession, corresponding to discrete vegetation stages before, during, and after the EPE interval. Collapse of the glossopterid biome marked the onset of the terrestrial EPE and may have significantly predated the marine mass extinctions and conodont-defined Permian–Triassic Boundary. Apart from extinction of the dominant Permian plant taxa, the EPE was characterized by a reduction in primary productivity, and the immediate aftermath was marked by high abundances of opportunistic fungi, algae, and ferns. This transition is coeval with the onset of a gradual global decrease in δ13Corg and the primary extrusive phase of Siberian Traps Large Igneous Province magmatism. The dominant gymnosperm groups of the Gondwanan Mesozoic (peltasperms, conifers, and corystosperms) all appeared soon after the collapse but remained rare throughout the immediate post-EPE succession. Faltering recovery was due to a succession of rapid and severe climatic stressors until at least the late Early Triassic. Immediately prior to the Smithian–Spathian boundary (ca. 249 Ma), indices of increased weathering, thick redbeds, and abundant pleuromeian lycophytes likely signify marked climate change and intensification of the Gondwanan monsoon climate system. This is the first record of the Smithian–Spathian floral overturn event in high southern latitudes.McConnell, J.R., Sigl, M., Plunkett, G., Burke, A., Kim, W.M., Raible, C.C., Wilson, A.I., Manning, J.G., Ludlow, F., Chellman, N.J., Innes, H.M., Yang, Z., Larsen, J.F., Schaefer, J.R., Kipfstuhl, S., Mojtabavi, S., Wilhelms, F., Opel, T., Meyer, H., Steffensen, J.P., 2020. Extreme climate after massive eruption of Alaska’s Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom. Proceedings of the National Academy of Sciences 117, 15443-15449.: The first century BCE fall of the Roman Republic and Ptolemaic Kingdom and subsequent rise of the Roman Empire were among the most important political transitions in the history of Western civilization. Volcanic fallout in well-dated Arctic ice core records, climate proxies, and Earth system modeling show that this transition occurred during an extreme cold period resulting from a massive eruption of Alaska’s Okmok volcano early in 43 BCE. Written sources describe unusual climate, crop failures, famine, disease, and unrest in the Mediterranean immediately following the eruption—suggesting significant vulnerability to hydroclimatic shocks in otherwise sophisticated and powerful ancient states. Such shocks must be seen as having played a role in the historical developments for which the period is famed.Abstract: The assassination of Julius Caesar in 44 BCE triggered a power struggle that ultimately ended the Roman Republic and, eventually, the Ptolemaic Kingdom, leading to the rise of the Roman Empire. Climate proxies and written documents indicate that this struggle occurred during a period of unusually inclement weather, famine, and disease in the Mediterranean region; historians have previously speculated that a large volcanic eruption of unknown origin was the most likely cause. Here we show using well-dated volcanic fallout records in six Arctic ice cores that one of the largest volcanic eruptions of the past 2,500 y occurred in early 43 BCE, with distinct geochemistry of tephra deposited during the event identifying the Okmok volcano in Alaska as the source. Climate proxy records show that 43 and 42 BCE were among the coldest years of recent millennia in the Northern Hemisphere at the start of one of the coldest decades. Earth system modeling suggests that radiative forcing from this massive, high-latitude eruption led to pronounced changes in hydroclimate, including seasonal temperatures in specific Mediterranean regions as much as 7 °C below normal during the 2 y period following the eruption and unusually wet conditions. While it is difficult to establish direct causal linkages to thinly documented historical events, the wet and very cold conditions from this massive eruption on the opposite side of Earth probably resulted in crop failures, famine, and disease, exacerbating social unrest and contributing to political realignments throughout the Mediterranean region at this critical juncture of Western civilization.McDonough, W.F., ?rámek, O., Wipperfurth, S.A., 2020. Radiogenic power and geoneutrino luminosity of the Earth and other terrestrial bodies through time. Geochemistry, Geophysics, Geosystems 21, e2019GC008865.: We report the Earth's rate of radiogenic heat production and (anti)neutrino luminosity from geologically relevant short‐lived radionuclides (SLR) and long‐lived radionuclides (LLR) using decay constants from the geological community, updated nuclear physics parameters, and calculations of the β spectra. We track the time evolution of the radiogenic power and luminosity of the Earth over the last 4.57 billion years, assuming an absolute abundance for the refractory elements in the silicate Earth and key volatile/refractory element ratios (e.g., Fe/Al, K/U, and Rb/Sr) to set the abundance levels for the moderately volatile elements. The relevant decays for the present‐day heat production in the Earth (19.9 ± 3.0?TW) are from 40K, 87Rb, 147Sm, 232Th, 235U, and 238U. Given element concentrations in kg‐element/kg‐rock and density ρ in kg/m3, a simplified equation to calculate the present‐day heat production in a rock is h[μWm-3] = p(3.387x10-3 K + 0.01139 Rb + 0.04594 Sm + 26.18 Th + 98.29 U)The radiogenic heating rate of Earth‐like material at solar system formation was some 103 to 104 times greater than present‐day values, largely due to decay of 26Al in the silicate fraction, which was the dominant radiogenic heat source for the first ～10?Ma. Assuming instantaneous Earth formation, the upper bound on radiogenic energy supplied by the most powerful short‐lived radionuclide 26Al (t 1/2 = 0.7?Ma) is 5.5×1031?J, which is comparable (within a factor of a few) to the planet's gravitational binding energy.Plain Language Summary: The decay of radioactive elements in planetary interiors produces heat that drives the dynamic processes of convection (core and mantle), melting, and volcanism in rocky bodies in the solar system and beyond. For elements with half‐lives of 100,000 to 100 billion years, uncertainties in their decay constants range from 0.2% to ～4%, and comparing data from physics versus geology shows differences of about 1% to 4%. These differences, combined with uncertainties in Q values (energy released in reaction), lead to diverging results for heat production and for predictions of the amount of energy removed from the rocky body by emitted (anti)neutrinos.Medina, O.E., Gallego, J., Nassar, N.N., Acevedo, S.A., Cortés, F.B., Franco, C.A., 2020. Thermo-oxidative decomposition behaviors of different sources of n-C7 asphaltenes under high-pressure conditions. Energy & Fuels 34, 8740-8758. of pressure on thermo-oxidative decomposition of different sources of n-C7 asphaltenes were investigated at high pressure using a thermogravimetric analyzer under an air atmosphere. The n-C7 asphaltenes were extracted from different heavy and extra-heavy crude oils around the world and were thoroughly characterized by elemental analysis (EA), vapor pressure osmometry (VPO), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and nuclear magnetic resonance (NMR) techniques. A high-pressure thermogravimetric analyzer coupled to a mass spectrometer was employed to obtain thermograms at 0.084, 3.0, and 6.0 MPa, and gaseous products were obtained by asphaltene decomposition. Kinetic analyses were performed for thermo-oxidative multistep reactions and compared based on the trends of pre-exponential factor and effective activation energies using an approximation of the Ozawa, Flynn, and Wall (OFW) isoconversional method. The n-C7 asphaltene decomposition profile was determined by four thermal events, namely, oxygen chemisorption (OC), desorption/decomposition of chemisorbed oxygen functional groups (DCO), and first and second combustion (FC and SC, respectively). We found that the amount of chemisorbed oxygen depends not so much on the oxygen percentage present in the n-C7 asphaltenes and aggregates but on whether it is found in a greater proportion as COO groups, independent of the used pressure. In addition, as the aromatization degree increases and the alkylation degree decreases, the amount of oxygen atoms chemisorbed also increases. As for the DCO region, it was corroborated that the increase in pressure from 0.084 to 6.0 MPa has a positive influence on the mass loss in this region for all samples used. The n-C7 asphaltenes with a higher chemisorption in the previous region showed a higher decomposition or loss of oxygenated compounds during DCO because there are more oxygenated groups in the basal plane of aromatic structures; therefore, the kinetics of the carbonaceous material consumption is increased. According to XPS analysis, n-C7 asphaltenes with a higher content of sulfur as thioethers show facilitated decomposition, due to the low energy required for their oxidation and subsequent cracking, throughout the range of evaluated pressures. Further, the higher content of hydrogen on α carbons to aromatic rings suggests that some of their small alkyl side chains are cracked in this zone due to the easy decomposition of α-methyl, α-methylene, and α-methine structures. As for the FC region, up to 3.0 MPa, a greater mass loss occurs in n-C7 asphaltenes with a high content of short aliphatic chains. Nevertheless, at 6.0 MPa, the mass loss percentage decreases in similar measures for all samples, indicating that under these conditions there is greater ease of breaking the functional groups located both in the basal plane of the aromatic rings and on the periphery of the molecule. Finally, during high-temperature oxidation reactions (SC), the higher aromaticity degree increases the percentage of mass loss. These findingsMelchionna, M., Profico, A., Castiglione, S., Sansalone, G., Serio, C., Mondanaro, A., Di Febbraro, M., Rook, L., Pandolfi, L., Di Vincenzo, F., Manzi, G., Raia, P., 2020. From smart apes to human brain boxes. A uniquely derived brain shape in late hominins clade. Frontiers in Earth Science 8, 273. doi: 10.3389/feart.2020.00273. humans have larger and more globular brains when compared to other primates. Such anatomical features are further reflected in the possession of a moderately asymmetrical brain with the two hemispheres apparently rotated counterclockwise and slid anteroposteriorly on one another, in what is traditionally described as the Yakovlevian torque. Developmental disturbance in human brain asymmetry, or lack thereof, has been linked to several cognitive disorders including schizophrenia and depression. More importantly, the presence of the Yakovlevian torque is often advocated as the exterior manifestation of our unparalleled cognitive abilities. Consequently, studies of brain size and asymmetry in our own lineage indirectly address the question of what, and when, made us humans, trying to trace the emergence of brain asymmetry and expansion of cortical areas back in our Homo antecedents. Here, we tackle this same issue by studying the evolution of human brain size, shape, and asymmetry on a phylogenetic tree including 19 apes and Homo species, inclusive of our fellow ancestors. We found that a significant positive shift in the rate of brain shape evolution pertains to the clade including modern humans, Neanderthals, and Homo heidelbergensis. Although the Yakovlevian torque is well evident in these species and levels of brain asymmetry are correlated to changes in brain shape, further early Homo species possess the torque. Even though a strong allometric component is present in hominoid brain shape variability, this component seems unrelated to asymmetry and to the rate shift we recorded. These results suggest that changes in brain size and asymmetry were not the sole factors behind the fast evolution of brain shape in the most recent Homo species. The emergence of handedness and early manifestations of cultural modernity in the archeological record nicely coincide with the same three species sharing the largest and most rapidly evolving brains among all hominoids.Melott, A.L., Thomas, B.C., 2020. From cosmic explosions to terrestrial fires? A reply. The Journal of Geology 128, 393-393. to Discussion of: Deschamps, F., Mottez, F., 2020. From cosmic explosions to terrestrial fires? A discussion. The Journal of Geology 128, 389-391.Original Article: Discussion of: Melott, A. L., and Thomas, B. C. 2019. From cosmic explosions to terrestrial fires? J. Geol. 127:475–481.Deschamps and Mottez (2020) argue that the Gauss-Matuyama magnetic field reversal at the Pliocene-Pleistocene boundary would have greatly lowered the overall ability of Earth’s magnetic field for a time order of 104 years, allowing many more cosmic rays to reach Earth’s atmosphere and surface. Deschamps and Mottez argue that this would enhance the effect we proposed in Melott and Thomas (2019).This argument is valid for most of the cosmic rays Earth receives today, which are below a billion (109) eV (1 GeV) in energy. These cosmic rays mostly affect only the upper atmosphere directly. However, as shown in figures 2 and 3 of our article, the inputs from nearby supernovae have energies up to a million times greater. Earth’s magnetic field is only effective for particles with rigidity below about 20 GV (Smart and Shea 2009); for protons, this energy is roughly 20 GeV, well below the energies to which our modeled supernova cosmic rays extend. This limited rigidity is the basis of their ability to penetrate to the troposphere and ionize it and, thus, is the basis of our hypothesis on the great increase of cloud-to-ground lightning. But because such cosmic rays are almost not at all deflected by Earth’s magnetic field, they would not be measurably enhanced by a magnetic field reversal. Ionization of the stratosphere and ozone depletion is possible by the cosmic rays deflected by the terrestrial magnetic field and might be slightly enhanced by the reversal.References Cited Deschamps, F., and Mottez, F. 2020. From cosmic explosions to terrestrial fires? a discussion. J. Geol. 128:389–391. Melott, A. L., and Thomas, B. C. 2019. From cosmic explosions to terrestrial fires? J. Geol. 127:475–481 Smart, D. F., and Shea, M. A. 2009. Fifty years of progress in geomagnetic cutoff rigidity determinations. Adv. Space Res. 44:1107–1123. Millan, M., Szopa, C., Buch, A., Summons, R.E., Navarro-Gonzalez, R., Mahaffy, P.R., Johnson, S.S., 2020. Influence of calcium perchlorate on organics under SAM-like pyrolysis conditions: Constraints on the nature of Martian organics. Journal of Geophysical Research: Planets 125, e2019JE006359.: Most of the organics detected on Mars so far are aliphatic and aromatic organo‐chlorine compounds. The smallest were first identified by the thermal treatment of the solid samples by Viking in 1976; although at the time, they were attributed to contamination. Since 2012, a larger variety of structures have been identified by the Sample Analysis at Mars experiment aboard the Curiosity rover. Evidence suggests that the chlorohydrocarbons formed during pyrolysis of sedimentary materials. Laboratory experiments show that heating of samples containing oxychlorines, such as chlorates (ClO3?) and perchlorates (ClO4?), along with organic matter present at Mars' surface is the logical source of these compounds. Nevertheless, this discovery of indigenous organic matter in the Mars regolith raises important questions: How do the oxychlorines influence the pyrolysis of organics? What are the organics precursors of the organo‐chlorinated molecules detected on Mars? Is there a way to identify the parent molecules in a sample after pyrolysis? This paper presents the results of systematic laboratory experiments of the products formed during the pyrolysis of organic compounds from three chemical families—polycyclic aromatic hydrocarbons, amino acids, and carboxylic acids—in presence of calcium perchlorates. Results show that the polycyclic aromatic hydrocarbon parent molecules and most of the carboxylic acids are still detectable after pyrolysis in presence of calcium perchlorate and that the degradation and/or evolution of all parent molecules mostly depends on their chemical nature. In addition, we demonstrate that the chlorohydrocarbons detected on Mars by the Sample Analysis at Mars instrument could come from the three chemical families studied.Plain Language Summary: Organic molecules are the building blocks of life as we know it, and detecting them on the surface of Mars has been one of the major goals of Mars exploration. Viking landers in 1976, followed by the Curiosity rover in 2012, discovered simple chlorine‐bearing organics on Mars. These chlorohydrocarbons are known to be mainly produced by the instrument itself, through chemical reactions at high temperatures between other organic molecules thermally extracted from solid rock and soil samples that react with the oxidizing minerals present on Mars (e.g., perchlorates). Studying the influence of the minerals like perchlorates on the thermal extraction of different parent molecules requires thorough experimental studies like this one. Our work constrains the potential parent molecules of the chlorohydrocarbons detected on Mars in the presence of calcium perchlorate, thereby shedding light on the past and present habitability of Mars.Milojevic, T., Zebec, Z., Schimak, M.P., 2020. Cultivation with powdered meteorite (NWA 1172) as the substrate enhances low-temperature preservation of the extreme thermoacidophile Metallosphaera sedula. Frontiers in Astronomy and Space Sciences 7, 37. doi: 10.3389/fspas.2020.00037. studies have uncovered a vast number of thermophilic species in icy environments, permanently cold ocean sediments, cold sea waters, and cool soils. The survival of thermophiles in psychrobiotic habitats requires thorough investigation of the physiological and molecular mechanisms behind their natural cryopreservation. Such investigations are mainly impeded due to a restricted cultivation of thermophiles at low temperatures under the laboratory conditions. Artificial culture media used under the laboratory conditions usually fail to support cultivation of thermophiles at low-temperature range. In this study we cultivated the extreme thermoacidophilic archaeon Metallosphaera sedula with the preliminary powdered and sterilized multimetallic extraterrestrial mineral material (the meteorite NWA 1172) under a low temperature regime in laboratory conditions. Our data indicate that M. sedula withstands cold stress and can be maintained at low temperatures, when supplemented with the meteorite NWA 1172 as the sole energy source. Cultivation with the meteorite NWA 1172 opens up new, previously unknown psychrotolerant characteristics of M. sedula, emphasizing that culture conditions (i.e., the “nutritional environment”) may affect the microbial survival potential in stress related situations. These observations facilitate further investigation of strategies and underlying molecular mechanisms of the survival of thermophilic species in permanently cold habitats.Mitchell, C.E., Melchin, M.J., 2020. Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation: COMMENT. Geology 48, e509. on: Bond, D.P.G., Grasby, S.E., 2020. Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation. Geology 48, 777-781.Reply to Comment by: Bond, D.P.G., Grasby, S.E., 2020. Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation: REPLY. Geology 48, e510-e510.Bond and Grasby (2020) assert that a large igneous province (LIP) eruption triggered the Late Ordovician mass extinction (LOME). This causal explanation requires a precise temporal correlation between LOME and LIP. Unfortunately, the paper employs a poor chronology of the extinction itself: that it was two nearly instantaneous pulses, the first coincident with the beginning of the Hirnantian and the second with the onset of postglacial rise. This common but unhelpful shorthand is made worse by the mis-correlation of those supposed pulses relative to the new geochemical data.The biozonation presented by Bond and Grasby (their figure 3) for the Dob’s Linn succession does not include significant revisions published since Williams (1988). The Extraordinarius Band contains Metabolograptus persculptus (Fig. 1), which defines the eponymous zone, and M. extraordinarius occurs in Anceps Band E, which is thus early Hirnantian (Melchin et al., 2003; see also Melchin et al., 2013). Furthermore, sedimentological analysis of the Dob’s Linn succession indicates that the Late Ordovician glacial maximum commenced immediately following deposition of Anceps Band D (Armstrong and Coe, 1997). Relative to the glacial chronology inferred on the basis of faunal and geochemical evidence, as well as direct evidence of glacially generated sediments in North Africa and Czechia (e.g., Mitchell et al., 2011; Melchin et al., 2013; Ghienne et al., 2014; Mauviel et al., 2020), it is likely that the Hirnantian Age began at Dob’s Linn shortly after deposition of Anceps Band D, instead of at the level of the Extraordinarius Band as depicted by Bond and Grasby. Bond and Grasby (their figure 2) rely on out-of-date summaries of the turnover event that they seek to explain. Large-scale sea-level change and displacement of facies and habitats accompanied the Hirnantian glaciation. Such changes make it very difficult to recover the precise timing of the LOME extinctions (Holland and Patzkowsky, 2015). Recent work suggests, however, that the LOME was a protracted turnover event that included considerable species evolution during the glacial interval rather than a flanking pair of abrupt extinctions. Graptolite species indeed show a peak of species losses in the late Katian to early Hirnantian (Crampton et al., 2016), but the event was long-lived and regionally diachronous, as were late Hirnantian to early Rhuddanian extinctions (Chen et al., 2005; Melchin et al., 2013; Sheets et al., 2016). Brachiopod faunal turnover during the LOME also was a long-term process (e.g., Rasmussen et al., 2019), which, in a broad facies transect in South China, appears to have been ongoing through much of the Hirnantian (Wang et al., 2019).Viewed in this revised context, the geochemical changes documented at Dob’s Linn by Bond and Grasby do not support the authors’ suggestion that a LIP contributed to the onset of the Hirnantian events. The peaks in Hg do not coincide closely with global maxima in the rates of extinction, and early Hirnantian sediments at Dob’s Linn reveal no sign of increased anoxia or volcanicity. Mo, F., Qi, Z., Yan, W., Huang, X., Li, J., 2020. Influence of water on gas transport in shale nanopores: Pore-scale simulation study. Energy & Fuels 34, 8239-8249. exists in shale gas reservoirs in the form of connate water and retained fracturing fluid. The nanoscale interaction between gas and water plays an important role in gas transport in shale nanopores. However, the research comprehensively focusing on gas–water transport in all pore types including organic pores, inorganic pores, and fractures is limited. In this work, we use a pore-scale model to study the influence of water on gas transport in shale nanopores. Shale pore structure of the model includes three organic pores, three inorganic pores, and one fracture. Because fluids have different transport behaviors in each sort of pore, a mathematical formulation is derived to describe fluid adsorption–desorption, diffusion, and flow (convection) in organic pores, inorganic pores, and fractures, respectively. The mathematical formulation is used in the model to simulate gas–water transport at a wide range of pressures and water saturations. The influence of water on gas transport is analyzed by comparing equivalent gas flow rate in two-phase cases and single-phase (gas) cases. Results indicate that the equivalent gas flow rate in two-phase cases is on average 43.03% of the equivalent gas flow rate in single-phase cases. The impact of water mainly happens in the fracture due to mutual interference of gas and water during two-phase flow. This effect induces a linear relation between equivalent gas flow rate and water saturation. The two-phase flow in the fracture dominates gas transport capability in shales. The gas in inorganic pores has much better movability than the gas in organic pores under a limited pressure drop. In the case of water saturation 40% and average pressure 22 MPa, most of the gas in inorganic pores can transport out of the matrix, while over 54% of the gas in organic pores fails to transport out. This implies that shale gas production largely depends on free gas transport. Enhancing adsorbed gas recovery is essential to maintain good well productivity.Mo, L., Dai, H., Feng, L., Liu, B., Li, X., Chen, Y., Khan, S., 2020. In-situ catalytic pyrolysis upgradation of microalgae into hydrocarbon rich bio-oil: Effects of nitrogen and carbon dioxide environment. Bioresource Technology 314, 123758. of Spirulina Platensis (SP) microalgae was carried out under different reaction environment such as nitrogen (N2) and carbon dioxide (CO2) at different reaction temperatures of 300, 350, 400, 450 and 500 °C. Catalytic upgradations were examined over solid acid (ZSM-5) and solid base (MgO) catalyst, and with ZSM-5-MgO catalysts mixtures. Results showed, pyrolysis of non-catalytic biomass yielded maximum bio-oil of 43.6% under N2. However catalytic upgradation in CO2 environment produced lower bio-oil due to the coke formation. Maximum bio-oil (46.2 wt%) was obtained with basic metal MgO catalyst in N2 environment compared to other catalyst and environments. Mixture of MgO-ZSM-5 catalyst improved the bio-oil yield (37.8–48.6 wt%) compared to individual catalytic reaction under N2 and CO2. Higher high heating value (HHV) was observed in catalytic bio-oil 36.8 MJ/Kg. Bio-oil (catalytic) analysis revealed that 64–70% of compounds are in hydrocarbon range. Bio-oil was rich in hydrocarbons of C7-C18 range with less oxygenated compounds.Mohammed, S., Opuwari, M., Titinchi, S., 2020. Source rock evaluation of Afowo clay type from the Eastern Dahomey Basin, Nigeria: insights from different measurements. Scientific Reports 10, 12036. Cretaceous Afowo Formation in the Eastern Dohamey Basin is characterized by an admixture of lithofacies ranging from sandstones, claystones, shales, clays, sand/shale, and sand/clay intercalations. The sandy facies, a mix of sandstone, clay, shale, and intercalations, contain biodegraded hydrocarbons while the shales and claystones that underlie it are rich in organic matter. The hydrocarbon-bearing interval is commonly referred to as the oil sand or tar sand. In this study, Afowo clay type underlying an outcrop of the oil sand was appraised for its hydrocarbon potential with loss on ignition, thermogravimetry, and rock evaluation pyrolysis. Results obtained from loss on ignition showed that total organic matter content, a proxy to total organic carbon, for the Afowo clay type ranged from 9.410 to 38.750 wt%. The organic maturation temperature (Tmax) was determined using both thermogravimetry and rock evaluation pyrolysis (Rock–Eval). Thermogravimetric analysis produced reliable Tmax within the range of 417–424?°C for all the samples. The results from rock evaluation pyrolysis on the same samples showed that total organic carbon ranged from 0.81 to 18.46 wt% with Tmax ranging from 417 to 424?°C. It was not possible to determine Tmax for one of the samples with Rock–Eval due to a small S2 value (0.22?mg Hc/g). The variations in organic matter contents from loss on ignition agree with total organic carbon computed from rock evaluation pyrolysis; samples with high organic matter contents have corresponding high TOC values. This study demonstrates that loss on ignition and thermogravimetry could complement and augment rock evaluation pyrolysis data for petroleum source rock characterization.M?ller, T.E., van der Bilt, W.G.M., Roerdink, D.L., J?rgensen, S.L., 2020. Microbial community structure in Arctic lake sediments reflect variations in Holocene climate conditions. Frontiers in Microbiology 11, 1520. doi: 10.3389/fmicb.2020.01520. reconstruction of past climate variability using physical and geochemical parameters from lake sedimentary records is a well-established and widely used approach. These geological records are also known to contain large and active microbial communities, believed to be responsive to their surroundings at the time of deposition, and proceed to interact intimately with their physical and chemical environment for millennia after deposition. However, less is known about the potential legacy of past climate conditions on the contemporary microbial community structure. We analysed two Holocene-length (past 10 ka BP) sediment cores from the glacier-fed Ymer Lake, located in a highly climate-sensitive region on south-eastern Greenland. By combining physical proxies, solid as well as fluid geochemistry, and microbial population profiling in a comprehensive statistical framework, we show that the microbial community structure clusters according to established lithological units, and thus captures past environmental conditions and climatic transitions. Further, comparative analyses of the two sedimentary records indicates that the manifestation of regional climate depends on local settings such as water column depth, which ultimately constrains microbial variability in the deposited sediments. The strong coupling between physical and geochemical shifts in the lake and microbial variation highlights the potential of molecular microbiological data to strengthen and refine existing sedimentological classifications of past environmental conditions and transitions. Furthermore, this coupling implies that microbially controlled transformation and partitioning of geochemical species (e.g., manganese and sulphate) in Ymer lake today is still affected by climatic conditions that prevailed thousands of years back in time.Mooshammer, M., Alves, R.J.E., Bayer, B., Melcher, M., Stieglmeier, M., Jochum, L., Rittmann, S.K.-M.R., Watzka, M., Schleper, C., Herndl, G.J., Wanek, W., 2020. Nitrogen isotope fractionation during archaeal ammonia oxidation: Coupled estimates from measurements of residual ammonium and accumulated nitrite. Frontiers in Microbiology 11, 1710. doi: 10.3389/fmicb.2020.01710. naturally occurring nitrogen (N) isotopes, 15N and 14N, exhibit different reaction rates during many microbial N transformation processes, which results in N isotope fractionation. Such isotope effects are critical parameters for interpreting natural stable isotope abundances as proxies for biological process rates in the environment across scales. The kinetic isotope effect of ammonia oxidation (AO) to nitrite (NO2–), performed by ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), is generally ascribed to the enzyme ammonia monooxygenase (AMO), which catalyzes the first step in this process. However, the kinetic isotope effect of AMO, or εAMO, has been typically determined based on isotope kinetics during product formation (cumulative product, NO2–) alone, which may have overestimated εAMO due to possible accumulation of chemical intermediates and alternative sinks of ammonia/ammonium (NH3/NH4+). Here, we analyzed 15N isotope fractionation during archaeal ammonia oxidation based on both isotopic changes in residual substrate (RS, NH4+) and cumulative product (CP, NO2–) pools in pure cultures of the soil strain Nitrososphaera viennensis EN76 and in highly enriched cultures of the marine strain Nitrosopumilus adriaticus NF5, under non-limiting substrate conditions. We obtained εAMO values of 31.9–33.1‰ for both strains based on RS (δ15NH4+) and showed that estimates based on CP (δ15NO2–) give larger isotope fractionation factors by 6–8‰. Complementary analyses showed that, at the end of the growth period, microbial biomass was 15N-enriched (10.1‰), whereas nitrous oxide (N2O) was highly 15N depleted (?38.1‰) relative to the initial substrate. Although we did not determine the isotope effect of NH4+ assimilation (biomass formation) and N2O production by AOA, our results nevertheless show that the discrepancy between εAMO estimates based on RS and CP might have derived from the incorporation of 15N-enriched residual NH4+ after AMO reaction into microbial biomass and that N2O production did not affect isotope fractionation estimates significantly.Móricz, ?.M., Lapat, V., Morlock, G.E., Ott, P.G., 2020. High-performance thin-layer chromatography hyphenated to high-performance liquid chromatography-diode array detection-mass spectrometry for characterization of coeluting isomers. Talanta 219, 121306. effect-directed analysis on a planar chromatogram allows for fast non-target screening, multi-imaging detection of effects (bioprofiling) and highly targeted characterization and isolation of bioactive compounds. For direct characterization by high-resolution mass spectrometry (HRMS), however, the orthogonal hyphenation of two different liquid chromatographic techniques (planar and column chromatography) is still underexplored. In particular, it can be helpful in case of coeluting compounds. Exemplarily, lemon balm (Melissa officinalis L.) leaf extract was analysed by high-performance thin-layer chromatography in combination with bioactivity assays for antibacterial (against the Gram-positive Bacillus subtilis and the Gram-negative Aliivibrio fischeri) and α-glucosidase-inhibitory compounds (HPTLC-UV/Vis/FLD-EDA). High-resolution mass spectra of two bioactive compound zones were directly recorded via an elution head-based interface. By HPTLC-HESI-HRMS, the compound in zone a inhibited A. fischeri and was identified as linolenic acid, whereas the two closely related constitutional isomers oleanolic acid and ursolic acid were present in zone b. This was proven by two-dimensional liquid chromatography. Heart-cutting HPTLC-UV/Vis/FLD-HPLC-DAD-MS allowed the separation of the two isomers and proved both to be present in the bioactive zone with ursolic acid at a much higher abundance.Morono, Y., Ito, M., Hoshino, T., Terada, T., Hori, T., Ikehara, M., D’Hondt, S., Inagaki, F., 2020. Aerobic microbial life persists in oxic marine sediment as old as 101.5 million years. Nature Communications 11, 3626. microbial populations persist from seafloor to basement in the slowly accumulating oxic sediment of the oligotrophic South Pacific Gyre (SPG). The physiological status of these communities, including their substrate metabolism, is previously unconstrained. Here we show that diverse aerobic members of communities in SPG sediments (4.3?101.5?Ma) are capable of readily incorporating carbon and nitrogen substrates and dividing. Most of the 6986 individual cells analyzed with nanometer-scale secondary ion mass spectrometry (NanoSIMS) actively incorporated isotope-labeled substrates. Many cells responded rapidly to incubation conditions, increasing total numbers by 4 orders of magnitude and taking up labeled carbon and nitrogen within 68 days after incubation. The response was generally faster (on average, 3.09 times) for nitrogen incorporation than for carbon incorporation. In contrast, anaerobic microbes were only minimally revived from this oxic sediment. Our results suggest that microbial communities widely distributed in organic-poor abyssal sediment consist mainly of aerobes that retain their metabolic potential under extremely low-energy conditions for up to 101.5?Ma.Mühlemann, B., Vinner, L., Margaryan, A., Wilhelmson, H., de la Fuente Castro, C., Allentoft, M.E., de Barros Damgaard, P., Hansen, A.J., Holtsmark Nielsen, S., Strand, L.M., Bill, J., Buzhilova, A., Pushkina, T., Falys, C., Khartanovich, V., Moiseyev, V., J?rkov, M.L.S., ?stergaard S?rensen, P., Magnusson, Y., Gustin, I., Schroeder, H., Sutter, G., Smith, G.L., Drosten, C., Fouchier, R.A.M., Smith, D.J., Willerslev, E., Jones, T.C., Sikora, M., 2020. Diverse variola virus (smallpox) strains were widespread in northern Europe in the Viking Age. Science 369, eaaw8977.: Smallpox, one of the most devastating human diseases, killed between 300 million and 500 million people in the 20th century alone. We recovered viral sequences from 13 northern European individuals, including 11 dated to ~600–1050 CE, overlapping the Viking Age, and reconstructed near-complete variola virus genomes for four of them. The samples predate the earliest confirmed smallpox cases by ~1000 years, and the sequences reveal a now-extinct sister clade of the modern variola viruses that were in circulation before the eradication of smallpox. We date the most recent common ancestor of variola virus to ~1700 years ago. Distinct patterns of gene inactivation in the four near-complete sequences show that different evolutionary paths of genotypic host adaptation resulted in variola viruses that circulated widely among humans.Editor's summary: Viking smallpox diversity. Humans have a notable capacity to withstand the ravages of infectious diseases. Smallpox killed millions of people but drove Jenner's invention of vaccination, which eventually led to the annihilation of this virus, declared in 1980. To investigate the history of smallpox, Mühlemann et al. obtained high-throughput shotgun sequencing data from 1867 human remains ranging from >31,000 to 150 years ago (see the Perspective by Alcamí). Thirteen positive samples emerged, 11 of which were northern European Viking Age people (6th to 7th century CE). Although the sequences were patchy and incomplete, four could be used to infer a phylogenetic tree. This showed distinct Viking Age lineages with multiple gene inactivations. The analysis pushes back the date of the earliest variola infection in humans by ～1000 years and reveals the existence of a previously unknown virus clade.Structured Abstractintroduction: Variola virus (VARV), the causative agent of smallpox, is estimated to have killed between 300 million and 500 million people in the 20?th century and was responsible for widespread mortality and suffering for at least several preceding centuries. Humans are the only known host of VARV, and smallpox was declared eradicated in 1980. The timeline of the emergence of smallpox in humans is unclear. Based on sequence data up to 360 years old, the most recent common ancestor of VARV has been dated to the 16th or 17th century. This contrasts with written records of possible smallpox infections dating back at least 3000 years and mummified remains suggestive of smallpox dating to 3570 years ago.Rationale: Ancient virus sequences recovered from archaeological remains provide direct molecular evidence of past infections, give detail of genetic changes that have occurred during the evolution of the virus, and can reveal viable virus sequence diversity not currently present in modern viruses. In the case of VARV, ancient sequences may also reduce the gap between the written historical record of possible early smallpox infections and the dating of the oldest available VARV sequences. We therefore screened high-throughput shotgun sequencing data from skeletal and dental remains of 1867 humans living in Eurasia and the Americas between ~31,630 and ~150 years ago for the presence of sequences matching VARV.Results: VARV sequences were recovered from 13 northern European individuals, including 11 dated to ~600–1050 CE, overlapping the Viking Age, and we reconstructed near-complete VARV genomes for four of them. The samples predate the earliest confirmed smallpox cases by ~1000 years. Eleven of the recovered sequences fall into a now-extinct sister clade of the modern VARVs in circulation prior to the eradication of smallpox, while two sequences from the 19th century group with modern VARV. The inferred date of the most recent common ancestor of VARV is ~1700 years ago.The number of functional genes is generally reduced in orthopoxviruses with narrow host ranges. A comparison of the gene content of the Viking Age sequences shows great contrast with that of modern VARV. Three genes that are active in all modern VARV sequences were inactive over 1000 years ago in some or all ancient VARV. Among 10 genes inactive in modern and Viking Age VARV, the mutations causing the inactivations are different and the genes are predicted to be active in the ancestor of both clades, suggesting parallel evolution. Fourteen genes inactivated in modern VARV are active in some or all of the ancient sequences, eight of which encode known virulence factors or immunomodulators. The active gene counts of the four higher-coverage Viking Age viral genomes provide snapshots from an ~350-year period, showing the reduction of gene content during the evolution of VARV. These genomes support suggestions that orthopoxvirus species derive from a common ancestor containing all genes present in orthopoxviruses today, with the reduction in active gene count conjectured to be the result of long-term adaptation within host species.Conclusion: The Viking Age sequences reported here push the definitive date of the earliest VARV infection in humans back by ~1000 years. These sequences, combined with early written records of VARV epidemics in southern and western Europe, suggest a pan-European presence of smallpox from the late 6th century. The ancient viruses are part of a previously unknown, now-extinct virus clade and were following a genotypic evolutionary path that differs from modern VARV. The reduction in gene content shows that multiple combinations of active genes have led to variola viruses capable of circulating widely within the human population.(Top left) Sample VK533 with dagger, in situ. (Bottom left) Positive sample locations. Higher- and lower-coverage samples have solid and open circles, respectively. (Right) Diverse gene inactivation patterns in the four higher-coverage 600–1000 CE Viking Age sequences, within clade and as compared to sequences from other human VARVs and the phylogenetically nearest animal poxviruses, camelpox and taterapox. Open circles show intact genes, circle colors (independent for each gene) indicate different inactivations. Gene names at the bottom.Muller, H., Alawani, N.A., Adam, F.M., 2020. Innate sulfur compounds as an internal standard for determining vacuum gas oil compositions by APPI FT-ICR MS. Energy & Fuels 34, 8260-8273. sulfur components in high boiling petroleum samples were used as an internal standard for the estimation of the sample’s composition through atmospheric pressure photo ionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The first step was recording a representative mass spectrum for the aromatic components through the use of a time-of-flight mass spectrometer (TOF MS) to tune the FT-ICR MS parameters. The molecular weight and number of sulfur atoms per species identified in the high-resolution measurement, their mass spectrometric abundance, and the total sulfur content were combined to calculate the mass fraction of each (and by sum all) aromatic sulfur species present. Aromatic hydrocarbon (HC) compound quantification was based on an equimolar response compared to the aromatic sulfur species. Nitrogen species were treated analogously to the sulfur compounds by distributing the total nitrogen content. The mass balance of all aromatic compounds yields the mass fraction of saturated compounds (saturates), which is not directly accessible through the APPI process. The validity and biases of this approach were evaluated on a series of vacuum distilled fractions with narrow boiling ranges using comprehensive two-dimensional gas chromatography (GCxGC) as a reference technique. There are clear biases of the presented mass spectrometric approach compared to the GCxGC analysis, especially the underestimation of monoaromatic compounds and the overestimation of diaromatic sulfur compounds (benzothiophenes); however, the results agree surprisingly well for saturated compounds and, overall, for the aromatic hydrocarbon- and sulfur-containing compound families. The saturates fraction results also matched reasonably with gravimetrically determined saturates contents, and the isolated fractions were further characterized using field desorption/field ionization TOF MS. The inclusion of saturated compound carbon number distribution, in combination with FT-ICR MS data, yields a more complete compositional description of the studied vacuum gas oil samples. The method was also applied to two typical boiling range vacuum gas oil samples (derived from a Norwegian and an Arabian crude oil) to provide an insight into the usefulness and limitations of high-resolution mass spectrometry in a semiquantitative context, which is deemed important for many oil and gas industry applications.Müller, K., Zahn, D., Fr?mel, T., Knepper, T.P., 2020. Matrix effects in the analysis of polar organic water contaminants with HILIC-ESI-MS. Analytical and Bioanalytical Chemistry 412, 4867-4879. effects have been shown to be very pronounced and highly variable in the analysis of mobile chemicals, which may severely exacerbate accurate quantification. These matrix effects, however, are still scarcely studied in combination with hydrophilic interaction liquid chromatography (HILIC) and for very polar chemicals. In this study, the matrix effects of 26 polar model analytes were investigated in enriched drinking water, wastewater treatment plant effluent and solutions of inorganic salts, utilizing post-column infusion of the analytes into a HILIC–electrospray ionisation (ESI)–high-resolution mass spectrometry system. These experiments revealed the occurrence of structure-specific and unspecific matrix effects. The unspecific matrix effects were mainly observed in positive ESI polarity and predominantly coincided with a high ion count, resulting in ion suppression of all analytes. Thus, the excess charge is hypothesized to be the limiting factor in ion formation. Structure-specific matrix effects were more pronounced in negative ESI polarity and even structurally similar compounds were observed to react entirely differently: perfluoroalkyl carboxylic acids were suppressed, while perfluoroalkane sulfonic acids were simultaneously enhanced. These matrix effects were traced back to inorganic anions and cations, which eluted over a significant fraction of the chromatographic run time with this setup. Hence, it was concluded that inorganic ions are a main cause for matrix effects in the analysis of mobile chemicals utilizing HILIC.Murakami, K., Nomura, D., Hashida, G., Nakaoka, S.-i., Kitade, Y., Hirano, D., Hirawake, T., Ohshima, K.I., 2020. Strong biological carbon uptake and carbonate chemistry associated with dense shelf water outflows in the Cape Darnley polynya, East Antarctica. Marine Chemistry 225, 103842. of dense shelf water (DSW) in coastal polynyas (open water or thin sea-ice cover) in the sea-ice zone around Antarctica supplies Antarctic Bottom Water (AABW) through overflow down the continental slope. In coastal polynyas, atmospheric carbon dioxide (CO2) is absorbed by the ocean in the early spring because of active primary production, and DSW formation is an important process for transporting this carbon from the sea surface to the deep ocean. However, there have been few quantitative evaluations of carbon consumption by active primary production and transport in coastal polynyas. Here, we examined the carbon dynamics in the Cape Darnley polynya (CDP), East Antarctica during austral summer 2009, by using carbonate system parameters combined with oceanographic mooring data. The partial pressure of CO2 in the CDP surface water was lower than that of the atmosphere and the mean and standard deviation of sea?air CO2 flux was estimated as ?6.5 ± 6.9 mmol C m?2 d?1 (a negative value indicates absorption of atmospheric CO2 by the ocean). Vertical profiles of dissolved inorganic carbon (DIC) concentration showed that concentrations in the bottom layer near the ocean floor were lower (by about 20 μmol kg?1) than those in the ambient water (e.g., modified Circumpolar Deep Water, mCDW). The low-DIC in the shelf water was maintained by the strong biological uptake of carbon imported from high-DIC mCDW within the water column. Therefore, low-DIC DSW overflowed down the continental slope, and low-DIC concentrations were maintained through an export pathway to the continental shelf. The annual production of dissolved organic carbon and particulate organic carbon on the shelf was estimated as 0.7 × 1011–1.5 × 1011 mol C using the data for the DIC of DSW and current velocity data from a mooring in the CDP. Our results provide quantitative estimates for the potential role of carbon consumption by the active primary production and carbon transport by dense water formation in Antarctic coastal polynyas.Naseri, S., Jamshidi, S., Taghikhani, V., 2020. A new multiphase and dynamic asphaltene deposition tool (MAD-ADEPT) to predict the deposition of asphaltene particles on tubing wall. Journal of Petroleum Science and Engineering 195, 107553. expounded, the precipitation and deposition of asphaltene particles in pipelines has been proved to be the most challenging flow assurance problem due to its unknown and complex behaviors. In this work, a new multicomponent, multiphase and dynamic tool was developed to model the aggregation and deposition of asphaltene particles in a bulk medium. The multiphase and dynamic asphaltene deposition tool, shortened as MAD-ADEPT is, in fact, a modified version of the previously developed ADEPT. The new tool was developed to make the asphaltene deposition and aggregation concepts in oil production wells more predictable. To tackle the complexity of the asphaltene problem, a bespoke algorithm was developed to predict asphaltene precipitation, aggregation and deposition. The algorithm was made up of three main modules, i.e., thermodynamic, preprocessor and integrated time step adaptive modules. In the thermodynamic module, the Peng-Robinson equation of state was used and fine-tuned to estimate the fluid properties of multiphase hydrocarbon systems, while the PC-SAFT equation of state was used in order to obtain the asphaltene precipitation phase envelope (APE). In the preprocessor module, the sensitivity of the system to the reduction of wellbore inner diameter (ID) was examined. In the main module which could dynamically model the asphaltene aggregation and deposition, a non-isothermal multiphase mechanistic model, a convective-diffusive-reactive model and a non-convective volume of fluid model were solved simultaneously with an adaptive time step selection method. The new MAD-ADEPT was utilized to simulate a real field case to predict the asphaltene deposition in different time and space intervals along the production tubing. The results obtained from MAD-ADEPT was validated by those scant field data available in the literature. The results confirmed that the new tool can predict the asphaltene deposition reliably at various operating conditions within a production system. Also, the effects of multiphase flow as well as wellbore configurational parameters were studied on the amount of asphaltene deposition thickness on tubing wall. The accuracy of the results for the case studies, fast rate of convergence and less CPU computation time are the clearest advantages of the new asphaltene deposition dynamic tool over the previously developed ones.Nasyrova, Z.R., Kayukova, G.P., Khasanova, N.M., Vakhin, A.V., 2020. Transformation of organic matter of Domanik rock from the Romashkino oilfield in sub- and supercritical water. Petroleum Chemistry 60, 683-692. transformation of the organic matter (OM) of low-permeable carbon-rich domanik rock of the Romashkino oilfield in sub- and supercritical water (SCW) at temperatures of 320, 374, and 420°C and pressures of 17, 24.6, and 24.4 MPa in a neutral medium has been studied. The original rock with a TOC content of 7% has a high oil generation potential and a low productivity index. The productivity index increases with an increase in the severity of the thermal treatment of the rock, which is due to intense kerogen degradation resulting in the formation of free hydrocarbons that are easy to recover from the rock. In rock extracts, in comparison with the original rock, the amount of saturated and aromatic hydrocarbons increases by more than two times and that of resin–asphaltene substances decreases. Distinctive features of the yields and compositions of rock extracts depending on the temperature of the experiments have been revealed. The highest yield of the extract was observed in the experiment with subcritical water at 320°C and associated with the degradation of resins and more complete extraction of asphaltenes and high-molecular-weight n-alkanes from the rock. Treatment in SCW at 374 and 420°C leads to intensive degradation of the kerogen structure involving the detachment of aliphatic chains from large fragments of kerogen and asphaltene macromolecules to form lower n-alkanes and carbon-rich substances, such as carbenes and carboids. The structure of asphaltenes becomes more condensed and oxidized in the SCW medium at 420°С, leading to a decrease in their paramagnetic properties. Using the EPR technique, the features of hyperfine splitting of the vanadyl complex line on 14N nitrogen nuclei have been revealed in the spectrum of asphaltenes of the SCW experiment at 420°С, indicating specific changes in their structure.Neil, C.W., Hjelm, R.P., Hawley, M.E., Watkins, E.B., Cockreham, C., Wu, D., Mao, Y., Fischer, T.B., Stokes, M.R., Xu, H., 2020. Small-angle neutron scattering (SANS) characterization of clay- and carbonate-rich shale at elevated pressures. Energy & Fuels 34, 8178-8185. oil and gas from shale formations have emerged as some of the fastest growing energy resources in the United States, providing both cleaner energy to consumers and reducing the nation’s reliance on energy imports. To properly harness these important natural resources, the nanopore structure of associated shales must be fully understood, particularly under hydraulic fracturing conditions, where they are exposed to both overburden compressive and hydrostatic fluid pressures. The current study uses small-angle neutron scattering (SANS) to characterize pore structure, including porosity, pore accessibility, and pore size distribution, in the 1–100 nm regime at elevated pressures for mineralogically distinct clay- and carbonate-rich shales from the Permian Basin. Unlike typical porosity measurement techniques, SANS is uniquely capable of characterizing both open and closed porosity, allowing measurement of how pore accessibility changes with pressure and determination of the size range of accessible versus inaccessible pores. The porosity of the clay-rich shale was 7.7%, compared to 0.51% for the carbonate-rich shale. However, only 2.6% of the nanopores in the carbonate-rich shale were inaccessible to water at 8 kPSI (55.1 MPa) compared to 7.8% for the clay-rich shale. Further analyses indicated that the closed pores fall within distinct size ranges, likely corresponding with the chemical nature of the pore host material. These results provide valuable insight into the effects of shale petrophysical properties on hydrocarbon extraction from unconventional reservoirs.Nemirovskaya, I.A., 2020. Hydrocarbons in the water and bottom sediments of the Barents Sea during ice cover variability. Geochemistry International 58, 822-834. hydrocarbons (HCs) were studied in water and bottom sediments sampled during cruises 67th and 68th (August–September 2016 and July–August 2017, respectively) of the R/V Akademik Mstislav Keldysh in the Barents Sea to determine the lateral and interannual variability of their concentrations and composition. It has been established that the HC distribution in water was mainly determined by natural factors and depended on the hydrological peculiarites in different areas of the sea. From autumn 2016 to summer 2017, hydrocarbon concentrations slightly increased (on average, from 3 to 5 ?g/L), which was related to a change in the biochemical composition of organic matter likely owing to the decrease of ice area. The content of HCs decreased mainly with the depth. An exception was observed in the area of troughs and deposits, where nepheloid bottom layers demonstrated an increase of HC concentration in suspended matter and in the surface layer of bottom sediments, whereas sedimentary sequence showed no correlation between HC distribution and organic carbon.Nemirovskaya, I.A., Zavyalov, P.O., Konovalov, B.V., Khramtsova, A.V., 2020. Content and composition of hydrocarbons in water and sediments in the area of Kerch Strait. Doklady Earth Sciences 492, 387-391. results of studying the content and composition of aliphatic hydrocarbons (AHCs) and polycyclic aromatic hydrocarbons (PAHs) in the suspended particulate matter of the surface water layer and in the surface layer of bottom sediments in Kerch Strait in April and September 2019 are given in comparison with other areas of the Black Sea. In spite of the high concentrations of AHCs, in waters of the strait (110–160 μg/L) and in sandy sediments (16–63 μg/g) in particular, the composition of alkanes does not correspond to oil because of the rapid transformation of oil AHCs. The contamination of water and sediments in the strait by oil HCs results in the presence of naphthenic-aromatic compounds in alkanes, the domination of phytane over pristine, and the domination of pyrogenic and to a smaller rate of oil HCs in the composition of o, F.C., Guaratini, T., Colepicolo, P., Gates, P.J., Lopes, N.P., 2020. Characteristic product ions of acetylene carotenoids by electrospray and nanospray ionization tandem mass spectrometry. Rapid Communications in Mass Spectrometry 34, e8811. constitute a large group of natural pigments produced by photosynthetic organisms (plants and algae) and non‐photosynthetic bacteria and fungi.1 They are responsible for several biochemical events that regulate the adaptation and survival of various organisms, including light harvesting, protection against UV radiation, and quenching of reactive oxygen species.2-5In animals, carotenoids play important roles in visual communication and sex behavior,6 modulation of the immune system,7 growth factors and intracellular signaling pathways, regulation of cell differentiation,8 and as precursors for the pigment vitamin A.9Carotenoids normally contain a C40 linear and symmetric skeleton with an extensive polyene chain, formed by head‐to‐tail condensation of eight isoprene units.10 These pigments possess unique chemical reactivity and light‐absorbing properties due to the long central conjugated polyene chain, a chromophore system with λ max at 400–500?nm. Modifications in the basic structure, such as cyclization, hydrogenation, dehydrogenation, hydroxylation, epoxidation, rearrangement, and addition of lateral groups, give rise to a complex variety of similar compounds with widespread isomerism.11About 750 carotenoids have been isolated from natural sources. More than 250 are of marine origin and show an interesting structural diversity, such as allenic (e.g. fucoxanthin) and all the acetylenic carotenoids (alloxanthin).12 Albeit most of the biosynthetic pathways leading to carotenoids have been proposed, little is still known about the final biosynthetic steps leading to the formation of both allenic and acetylenic bonds.13, 14The economic relevance of carotenoids has driven the development of reliable analytical methodologies to analyze these pigments in food and other biological matrices.15 Mass spectrometry (MS) is currently the preferred technique for determining the identity of carotenoids in complex samples. It allows one to distinguish between co‐eluting compounds, when coupled with chromatographic systems, and it provides structural information on the basis of molecular masses, using high‐resolution MS and key product ions through application of tandem mass spectrometry (MS/MS or MS2).16-19Various approaches have explored carotenoid behavior through a variety of ionization techniques, including electron ionization (EI), fast atom bombardment, chemical ionization, matrix‐assisted laser desorption/ionization, electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI).20-23 EI has been applied to evaluate the fragmentation pathways of carotenoids through radical ion formation and redox reactions.24-27 Most recently, APCI combined with collision‐induced dissociation (CID) experiments has been used to identify characteristic product ions that can be associated with specific functional groups in the structures of these compounds.20, 22Previously, we reported the fragmentation of protonated carotenoids using ESI‐ and nanospray‐CID‐MS/MS.28 The results were compared with the characteristic carotenoid ions proposed by APCI‐MS/MS studies.20 It was demonstrated that product ions of protonated carotenoids derived from charge‐remote electrocyclic and retro‐ene eliminations. These mechanisms rely on the correct conformation and distribution of hydrogens, achieved during protonation of the polyene chain, which form a carbocation intermediate and induce cis –trans isomerization.28 In addition to the characteristic elimination of the aromatic ring from the polyene chain by 8π/6π electron electrocyclization,29 we also provided diagnostic product ions for keto‐carotenoids, generated by vinyl–allyl cleavage,30 and epoxy‐carotenes, with formation of oxonium ions.24, 28Herein we investigate the gas‐phase reactions of acetylenic carotenoids by ESI‐ and nanospray‐CID‐MS/MS, and provide key product ions for their rapid detection.Ultrahigh‐resolution accurate‐mass ESI‐MS/MS analyses were performed using a 7 T Apex IV Fourier transform ion cyclotron resonance instrument (Bruker Daltonics, Billerica, MA, USA) using an Apollo off‐axis ESI source. Samples were directly infused from a syringe pump at 100 μL min?1. The acquisition parameters were: capillary voltage, 4600 V; endplate voltage, 3500 V; capillary exit potential, 200 V; drying gas temperature, 200°C. Spectra were obtained by summing eighty 0.5 s scans. CID‐MS/MS product ion analyses were performed on the isolated [M+H]+ precursor ions using N2 as the collision gas. Nanospray ionization analyses were performed using a QStar‐XL quadrupole time‐of‐flight hybrid instrument (Applied Biosystems, Warrington, UK) with a Nanomate 100 automatic chip‐based nanospray system (Advion Biosciences, Norwich, UK). The QStar acquisition parameters were: ion source gas flow rate, 50 arbitrary units; curtain gas flow rate, 20 arbitrary units; ionspray voltage, 2700 V; declustering potential, 75 V; focusing potential, 280 V (see ESI‐MS/MS spectra in supporting information). The MS/MS analyses of the carotenoid pigments alloxanthin, diadinoxanthin, and diatoxanthin (Figure S1, supporting information) by the two tandem mass spectral techniques described above exhibited product ions at m /z 217 and 199. Accurate mass measurements by ultrahigh‐resolution ESI‐FTICR MS/MS analysis (Figures 1A‐1C) allow unequivocal determination of the formulae of the two product ions, as shown in Table 1. These product ions are only observed in carotenoids that contain acetylenic bonds in the polyene chain. Similar ions were also detected in MS/MS spectra deposited in the public MASSBANK database (see supporting information).31The fragmentation of acetylenic carotenoids was initiated with selection of the protonated molecule [M?+?H]+ as the precursor ion. Protonation is favored when using protic solvents mixed with 0.5% formic acid prior to ionization. According to previous studies, protonation of carotenoids preferably occurs between C7 and C11, even in the presence of oxygen atoms in the xanthophyll.28, 32, 33 During the ionization and subsequent CID fragmentation, the internal energy of the analytes increases sufficiently to induce isomerization of the polyene chain. We observed dehydration of hydroxyl substituents, similar to those previously detected for xanthophylls,20 and sequential cleavages of the polyene chain, which includes the diagnostic loss of toluene and/or xylene.29 The formation of the key product ion at m /z 217 arises from the transfer of the γ‐hydrogen atom to an unsaturated center via a six‐electron cyclic transition state, resulting in the formation of a conjugated diene and an allyl ion (Figure 1D). Several cleavages of the polyene chain by sequential pericyclic charge‐remote reactions are characteristic of carotenoids. Due to the sp orbitals at C7–C8, this retro‐ene reaction is chosen to attain the proper structural conformation and the hydrogen requirements. The product ion at m /z 199 occurs through a further dehydration of m /z 217, possibly via a 1,2‐elimination. As a carotenoid epoxide, diadinoxanthin also showed a product ion at m /z 221, formed by epoxide–furanoxide rearrangement with formation of cyclic oxonium ion, as summarized in Figure 2.28The ultrahigh‐resolution accurate‐mass analysis supports the evidence of C15H21O+ as m /z 217 and C15H19+ as m /z 199, providing key product ions for the rapid detection of acetylenic carotenoids. These results expand the set of diagnostic product ions for carotenoids analyzed by ESI‐MS/MS, and provide structural information to assist their characterization via CID‐MS. References1. Alcaíno J, Baeza M, Cifuentes V. Carotenoid distribution in nature. In: C Stange, ed. Carotenoids in Nature. Biosynthesis, Regulation and Function. Cham: Springer International Publishing; 2016: 3– 33. . Mathews MM, Sistrom WR. Function of carotenoid pigments in non‐photosynthetic bacteria. Nature. 1959; 184(4702): 1892‐ 1893. . Leverenz RL, Sutter M, Wilson A, et al. A 12 ? carotenoid translocation in a photoswitch associated with cyanobacterial photoprotection. Science. 2015; 348(6242): 1463LP‐ 1466. 4. Palozza P, Parrone N, Simone R, Catalano A. Role of lycopene in the control of ROS‐mediated cell growth: Implications in cancer prevention. Curr Med Chem. 2011; 18(12): 1846‐ 1860. 5. Havaux M. Carotenoids as membrane stabilizers in chloroplasts. Trends Plant Sci. 1998; 3(4): 147‐ 151. (98)01200-X6. Svensson PA, Wong BBM. Carotenoid‐based signals in behavioural ecology: A review. Behaviour. 2011; 148(2): 131‐ 189. . Chew BP, Park JS. Carotenoid action on the immune response. J Nutr. 2004; 134(1): 257S‐ 261S. . Palozza P, Serini S, Di Nicuolo F, Calviello G. Modulation of apoptotic signalling by carotenoids in cancer cells. Arch Biochem Biophys. 2004; 430(1): 104‐ 109. ttps://10.1016/j.abb.2004.02.0389. Dingle JT, Lucy JA. Vitamin A, carotenoids and cell function. Biol Rev. 1965; 40(3): 422‐ 458. Wiley Online Library | CAS | PubMed | Web of Science? | Google Scholar 10. Moise AR, Al‐Babili S, Wurtzel ET. Mechanistic aspects of carotenoid biosynthesis. Chem Rev. 2014; 114(1): 164‐ 193. . Amorim‐Carrilho KT, Cepeda A, Fente C, Regal P. Review of methods for analysis of carotenoids. TrAC Trends Anal Chem. 2014; 56: 49‐ 73. . Galasso C, Corinaldesi C, Sansone C. Carotenoids from marine organisms: Biological functions and industrial applications. Antioxidants. 2017; 6(4): 96. . Maresca JA, Graham JE, Bryant DA. The biochemical basis for structural diversity in the carotenoids of chlorophototrophic bacteria. Photosynth Res. 2008; 97(2): 121‐ 140. . Dambek M, Eilers U, Breitenbach J, Steiger S, Buchel C, Sandmann G. 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Mass spectrometry of carotenoid epoxides and furanoid oxides. Chem Commun. 1966; 23: 852. . Baldas J, Porter QN, Leftwick AP, Holzel R, Weedon BCL, Szabolcs J. Mass spectrometry of carotenoid ketones. J Chem Soc D Chem Commun. 1969; 8: 415. . Enzell CR, Francis GW, Liaaen‐Jensen S, et al. Mass spectrometric studies of carotenoids. 2. A survey of fragmentation reactions. Acta Chem Scand. 1969; 23(8): 727‐ 750. . Uarrota VG, Moresco R, Coelho B, et al. Metabolomics combined with chemometric tools (PCA, HCA, PLS‐DA and SVM) for screening cassava (Manihot esculenta Crantz) roots during postharvest physiological deterioration. Food Chem. 2014; 161: 67‐ 78. . Carnevale Neto F, Guaratini T, Costa‐Lotufo L, Colepicolo P, Gates PJ, Lopes NP. Re‐investigation of the fragmentation of protonated carotenoids by electrospray ionization and nanospray tandem mass spectrometry. Rapid Commun Mass Spectrom. 2016; 30(13): 1540‐ 1548. . Guaratini T, Lopes NP, Pinto E, Colepicolo P, Gates PJ. Mechanism for the elimination of aromatic molecules from polyenes in tandem mass spectrometry. Chem Commun. 2006; 39: 4110‐ 4112. . Hsu F‐F, Turk J. Elucidation of the double‐bond position of long‐chain unsaturated fatty acids by multiple‐stage linear ion‐trap mass spectrometry with electrospray ionization. J Am Soc Mass Spectrom. 2008; 19(11): 1673‐ 1680. . Horai H, Arita M, Kanaya S, et al. MassBank: A public repository for sharing mass spectral data for life sciences. J Mass Spectrom. 2010; 45(7): 703‐ 714. . Konovalov V, Kispert L. AM1, INDO/S and optical studies of carbocations of carotenoid molecules. Acid induced isomerization. J Chem Soc Perkin Trans 2. 1999;(4): 901‐ 910. . Kildahl‐Andersen G, Lutnaes BF, Krane J, Liaaen‐Jensen S. Structure elucidation of polyene systems with extensive charge delocalization carbocations from allylic carotenols. Org Lett. 2003; 5(15): 2675‐ 2678. , S.A., Lincoln, S.A., O'Reilly, S., Liu, X., Shock, E.L., Kelemen, P.B., Summons, R.E., 2020. Lipid biomarker record of the serpentinite-hosted ecosystem of the Samail ophiolite, Oman and implications for the search for biosignatures on Mars. Astrobiology 20, 830-845. is a weathering process in which ultramafic rocks react with water, generating a range of products, including serpentine and other minerals, in addition to H2 and low-molecular-weight hydrocarbons that are capable of sustaining microbial life. Lipid biomarker analyses of serpentinite-hosted ecosystems hold promise as tools for investigating microbial activity in ancient Earth environments and other terrestrial planets such as Mars because lipids have the potential for longer term preservation relative to DNA, proteins, and other more labile organic molecules. Here, we report the first lipid biomarker record of microbial activity in the mantle section of the Samail Ophiolite, in the Sultanate of Oman, a site undergoing active serpentinization. We detected isoprenoidal (archaeal) and branched (bacterial) glycerol dialkyl glycerol tetraether (GDGT) lipids, including those with 0–3 cyclopentane moieties, and crenarchaeol, an isoprenoidal GDGT containing four cyclopentane and one cyclohexane moieties, as well as monoether lipids and fatty acids indicative of sulfate-reducing bacteria. Comparison of our geochemical data and 16S rRNA data from the Samail Ophiolite with those from other serpentinite-hosted sites identifies the existence of a common core serpentinization microbiome. In light of these findings, we also discuss the preservation potential of serpentinite lipid biomarker assemblages on Earth and Mars. Continuing investigations of the Samail Ophiolite and other terrestrial analogues will enhance our understanding of microbial habitability and diversity in serpentinite-hosted environments on Earth and elsewhere in the Solar System. Nicholes, M.J., Williamson, C., Tranter, M., Holland, A., Yallop, M., Anesio, A., 2020. Photodegradation and biodegradation of dissolved organic matter on the surface of the Greenland Ice Sheet. Biogeosciences Discussions 2020, 1-31. surface (supraglacial) environment of the Greenland Ice Sheet (GrIS) is an active site for the storage, transformation and transport of carbon, which is driven by extremely high levels of solar radiation throughout the ablation season. Within the south west of the GrIS, blooms of Streptophyte micro-algae (hereafter glacier algae) at abundances of ~?105?cell?mL?1 dominate primary production in the surface ice and provide dissolved organic matter (DOM) to the heterotrophic bacterial community. Glacier algae contain photoprotective secondary phenolic pigment that comprises a large proportion of the cell (~?4?% of the dry weight) and could represent a substantial, additional carbon source for the heterotrophic community. The transformation and degradation of DOM by solar radiation (photodegradation) and heterotrophic communities (biodegradation) represent two crucial controls on DOM composition and quantity; however, the influence of these processes within the surface ice is yet to be constrained. This study therefore assessed responses in the composition and quantity of two carbon sources (glacier algae secondary pigment and surface ice DOM) following exposure to UV, PAR, UV+PAR (photodegradation) and subsequent incubation with bacterial communities isolated from the ambient environment (biodegradation). Our results indicate that exposure to predominantly UV radiation altered the composition of glacier algal pigment and surface ice DOM; however, the quantity of DOM remained constant. Biodegradation caused the greatest changes to both DOM composition and quantity, particularly in surface ice DOM. Secondary pigment extracted from glacier algae was not a highly bioavailable source of carbon and did not support significant growth of surface ice heterotrophic bacterial communities. Conversely, low molecular weight compounds in surface ice DOM were rapidly utilised by heterotrophic bacteria supporting between a 3 and 9-fold increase in bacterial abundance over a 30-day incubation. We found that photodegradation of glacier algal pigment and surface ice DOM did not influence heterotrophic consumption. Photodegradation and biodegradation of DOM in the surface ice habitat are likely intimately linked and act as fundamental controls on the composition and quantity of DOM exported to downstream environments.Nie, R.-S., Wang, Y.-M., Kang, Y.-L., Jia, Y.-L., 2020. A steam rising model of steam-assisted gravity drainage production for heavy oil reservoirs. Energy Exploration & Exploitation 38, 801-818. steam chamber rising process is an essential feature of steam-assisted gravity drainage. The development of a steam chamber and its production capabilities have been the focus of various studies. In this paper, a new analytical model is proposed that mimics the steam chamber development and predicts the oil production rate during the steam chamber rising stage. The steam chamber was assumed to have a circular geometry relative to a plane. The model includes determining the relation between the steam chamber development and the production capability. The daily oil production, steam oil ratio, and rising height of the steam chamber curves influenced by different model parameters were drawn. In addition, the curve sensitivities to different model parameters were thoroughly considered. The findings are as follows: The daily oil production increases with the steam injection rate, the steam quality, and the degree of utilization of a horizontal well. In addition, the steam oil ratio decreases with the steam quality and the degree of utilization of a horizontal well. Finally, the rising height of the steam chamber increases with the steam injection rate and steam quality, but decreases with the horizontal well length. The steam chamber rising rate, the location of the steam chamber interface, the rising time, and the daily oil production at a certain steam injection rate were also predicted. An example application showed that the proposed model is able to predict the oil production rate and describe the steam chamber development during the steam chamber rising stage.Nikolskaya, E., Hiltunen, Y., 2020. Time-domain NMR in characterization of liquid fuels: A mini-review. Energy & Fuels 34, 7929-7934. nuclear magnetic resonance (LF-NMR) is a highly promising method for characterizing the different physical parameters and chemical structures of liquid fuels. In particular, there have been a variety of essential applications by means of time-domain NMR (TD-NMR). These applications can be developed for the characterization of petroleum fuels and biofuels, reaction monitoring, or process and quality control of liquid fuels. However, only a few applications have demonstrated the use of TD-NMR via on-line measurements. The principle of the majority of reviewed TD-NMR applications is based on finding the correlation between NMR and physical parameters. Special attention in this mini-review is paid to the description of on-line TD-NMR applications.Niles, S.F., Chacón-Pati?o, M.L., Putnam, S.P., Rodgers, R.P., Marshall, A.G., 2020. Characterization of an asphalt binder and photoproducts by Fourier transform ion cyclotron resonance mass spectrometry reveals abundant water-soluble hydrocarbons. Environmental Science & Technology 54, 8830-8836. asphalt is comprised of aggregate (rocks) mixed with a binder composed of high-boiling petroleum-derived compounds, which have been thought to be relatively inert (unreactive) and thus leach small amounts of polyaromatic hydrocarbons (PAHs) into water from the built environment. However, recent studies have demonstrated that petroleum readily undergoes photooxidation and generates water-soluble oxygen-containing hydrocarbons. Therefore, here, we investigate the effects of solar irradiation on an asphalt binder. Upon irradiation in a photooxidation microcosm, thin films of the asphalt binder produce abundant oil- and water-soluble oxygenated hydrocarbons, which we hypothesize are also leached from roads and highways through photooxidation reactions. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) enables extensive compositional characterization of the virgin asphalt binder, irradiated asphalt binder, and the water-soluble photoproducts. The results reveal the production of water-soluble species that resemble the molecular composition of petroleum-derived dissolved organic matter, including abundant hydrocarbons and S-containing species with up to 18 oxygen atoms. The results also confirm photo-induced oxidation, fragmentation, and potentially polymerization as active processes involved in the production of water-soluble organic pollutants from asphalt.Norell, M.A., Wiemann, J., Fabbri, M., Yu, C., Marsicano, C.A., Moore-Nall, A., Varricchio, D.J., Pol, D., Zelenitsky, D.K., 2020. The first dinosaur egg was soft. Nature 583, 406-410. eggshells protect developing embryos against environmental stress and contribute to reproductive success. As modern crocodilians and birds lay hard-shelled eggs, this eggshell type has been inferred for non-avian dinosaurs. Known dinosaur eggshells are characterized by an innermost membrane, an overlying protein matrix containing calcite, and an outermost waxy cuticle. The calcitic eggshell consists of one or more ultrastructural layers that differ markedly among the three major dinosaur clades, as do the configurations of respiratory pores. So far, only hadrosaurid, a few sauropodomorph and tetanuran eggshells have been discovered; the paucity of the fossil record and the lack of intermediate eggshell types challenge efforts to homologize eggshell structures across all dinosaurs. Here we present mineralogical, organochemical and ultrastructural evidence for an originally non-biomineralized, soft-shelled nature of exceptionally preserved ornithischian Protoceratops and basal sauropodomorph Mussaurus eggs. Statistical evaluation of in situ Raman spectra obtained for a representative set of hard- and soft-shelled, fossil and extant diapsid eggshells clusters the originally organic but secondarily phosphatized Protoceratops and the organic Mussaurus eggshells with soft, non-biomineralized eggshells. Histology corroborates the organic composition of these soft-shelled dinosaur eggs, revealing a stratified arrangement resembling turtle soft eggshell. Through an ancestral-state reconstruction of composition and ultrastructure, we compare eggshells from Protoceratops and Mussaurus with those from other diapsids, revealing that the first dinosaur egg was soft-shelled. The calcified, hard-shelled dinosaur egg evolved independently at least three times throughout the Mesozoic era, explaining the bias towards eggshells of derived dinosaurs in the fossil record.O'Connor, K.F., Berke, M.A., Ziolkowski, L.A., 2020. Hydrogen isotope fractionation in modern plants along a boreal-tundra transect in Alaska. Organic Geochemistry 147, 104064. increasing number of studies from high latitude settings use the stable hydrogen isotope ratio (δ2H) of plant leaf waxes to quantify changes in past precipitation. Calibration of modern vegetation and source water use from these landscapes is important to more accurately reconstruct past hydroclimate variability using sedimentary leaf wax δ2H values. Here, we determine plant-water fractionations from 12 sites along a south-north transect in central Alaska, from Fairbanks to Deadhorse (64-70°N). We characterize the δ2H values of n-alkanes and n-alkanoic acids from modern plants and their xylem and leaf water δ2H values, as well as plant source water using surface soils, a soil core, and previously collected meteoric water data from the region. We find both transpiration (εLW/XW) and biosynthetic (εwax/LW) fractionation are sensitive to environmental controls with latitude, with increased leaf transpiration and biosynthetic fractionation to the north, potentially due to increased summer sunlight hours. Soil water δ2H values show near linear 2H enrichment toward the surface associated with evaporation, with the δ2H value ～40?cm matching mean annual precipitation (MAP). Average net fractionation was calculated using xylem water and chain length weighted wax δ2H values (εwax/XW) and we find nearly the same mean values for both n-alkanes, ?112?±?27‰, and n-alkanoic acids, ?110?±?23‰, from 12 common high latitude vascular plants. To provide the range of likely net fractionations along this transect, we also calculate the average net fractionation using MAP, finding values are less negative than using xylem waters (εwax/MAP, ?89?±?28‰ for n-alkanes, and ?86?±?24‰ for n-alkanoic acids). To compare across studies, we determined the average εwax/MAP of n-alkanes from all available high latitude calibration studies and found more 2H enriched (smaller fractionations) for C27 (-87?±?29‰), C29 (-87?±?32‰), and C31 (-91?±?31‰) than those of global εwax/MAP homolog averages. This new work in Alaska contributes to our growing understanding of plant water-wax fractionation in the high latitudes and is potentially important for the use of sedimentary δ2H values for paleoprecipitation estimates.Ochoa, G.S., Prebihalo, S.E., Reaser, B.C., Marney, L.C., Synovec, R.E., 2020. Statistical inference of mass channel purity from Fisher ratio analysis using comprehensive two-dimensional gas chromatography with time of flight mass spectrometry data. Journal of Chromatography A 1627, 461401. Fisher ratio (F-ratio) analysis has recently been developed and validated for discovery-based studies of highly complex data collected using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). In previous studies, interpretation and utilization of F-ratio hit lists has relied upon manual decomposition and quantification performed by chemometric methods such as parallel factor analysis (PARAFAC), or via manual translation of the F-ratio hit list information to peak table quantitative information provided by the instrument software (ChromaTOF). Both of these quantification approaches are bottlenecks in the overall workflow. In order to address this issue, a more automatable approach to provide accurate relative quantification for F-ratio analyses was investigated, based upon the mass spectral selectivity provided via the F-ratio spectral output. Diesel fuel spiked with 15 analytes at four concentration levels (80, 40, 20, and 10 ppm) produced three sets of two class comparisons that were submitted to tile-based F-ratio analysis to obtain three hit lists, with an F-ratio spectrum for each hit. A novel algorithm which calculates the signal ratio (S-ratio) between two classes (eg., 80 ppm versus 40 ppm) was applied to all mass channels (m/z) in the F-ratio spectrum for each hit. A lack of fit (LOF) metric was utilized as a measure of peak purity and combined with F-ratio and p-values to study the relationship of each of these metrics with m/z purity. Application of a LOF threshold coupled with a p-value threshold yielded a subset of the most pure m/z for each of the 15 spiked analytes, evident by the low deviations (< 5%) in S-ratio relative to the true concentration ratio. A key outcome of this study was to demonstrate the isolation of pure m/z without the need for higher level signal decomposition algorithms.Ohkubo, S., Saito, T., Abul Kalam Azad, M., Kawai, H., Suda, W., Kore-eda, S., Hamamoto, S., Saito, H., Takemura, T., Komatsu, T., Ohnishi, J.-i., 2020. Microbial community structures in terrestrial subsurface sediments from the southern Kanto Plain, Japan. Geomicrobiology Journal 37, 595-602. community structure reflects the surrounding natural environment and changes to that environment. Although the subsurface at 5–100?m depth is important for human activities and there are potential risks of environmental pollution in this region, there have been only a few reports of subsurface microbial community structures in terrestrial areas. We investigated the diversity and community compositions of Bacteria and Archaea in boring cores collected from various depths at three different sites in the southern Kanto Plain, Japan. The results of 16S rRNA gene amplicon sequencing using MiSeq showed that the microbial community composition varied with the geological unit. Proteobacteria (Alphaproteobacteria and Gammaproteobacteria) were dominant members within sediments accumulated during the Pleistocene in the Musashino Upland. In contrast, Acidobacteria and Chloroflexi characteristically appeared in the Holocene layers of the Arakawa Lowland. These data suggest that the subsurface microbial composition is controlled by the geological features of the sediments.Ohmoto, H., 2020. A seawater-sulfate origin for early Earth’s volcanic sulfur. Nature Geoscience 13, 576-583. fractionation of sulfur isotopes (MIF-S)—as recorded primarily in pre-2.5 billion years ago (Ga) sedimentary rocks—has been interpreted as evidence of photolysis of volcanic SO2 in an anoxic troposphere. Here, I present thermodynamic and kinetic calculations, combined with data on the geology, mineralogy and chemical and isotopic compositions of modern and Archaean (3.8–2.5?Ga) aged volcanic samples from different tectonic settings, to examine early Earth’s sulfur cycle. Based partly on the similarities between submarine hydrothermal deposits and arc volcanic rocks in pyrite (FeS2) abundances and sulfur isotopic compositions (for example, the presence of both positive and negative δ34S values), I conclude that degassing of sulfur (mostly as SO2) into the atmosphere has been carried out primarily by subaerial eruptions of oxidized, arc-like magmas since at least 3.5?Ga. The generation of volcanic SO2 requires plate tectonics and the involvement of sulfate-rich seawater, which requires large exposed lands and an oxygenated atmosphere. I propose that the MIF-S signatures in sedimentary rocks were created by ultraviolet photochemical reactions between SO2 from explosive volcanic eruptions and O2 in the stratosphere, above an oxygen-rich troposphere, or by high-temperature reactions between organic compounds and sulfate in the oceans.Ojo, O.F., Farinmade, A., John, V., Nguyen, D., 2020. A nanocomposite of halloysite/surfactant/wax to inhibit surfactant adsorption onto reservoir rock surfaces for improved oil recovery. Energy & Fuels 34, 8074-8084. adsorption onto reservoir rock surfaces is a major issue in enhanced oil recovery (EOR) applications, decreasing the economic success of an EOR project. A method to minimize loss of surfactant is to encapsulate the surfactant and deliver it directly to the oil–water interface. This can be done through the use of naturally occurring clay nanotubes known as halloysites, where surfactants can be encapsulated in the lumen of the nanotubes. Halloysite nanotubes are about 1 μm in length with an outer diameter of about 70 nm and a lumen diameter of about 50 nm. These natural clay nanotubes are thermally stable, inexpensive, abundantly available, and environmentally friendly. An interesting aspect of the halloysite is that it has a predominantly negatively charged outer silica surface and a positively charged inner alumina surface. The surfactants are loaded into the halloysite nanotubes (HNTs) and coated with a thin layer of paraffin wax through a vacuum suction and solvent evaporation method. A thin paraffin wax coating/skin over the surfactant-loaded halloysites prevents the premature release of surfactants until they are in contact with oil, which promotes dissolution of the wax, releasing the surfactant. Imbibition experiments are carried out by measuring oil recovered after pushing injection fluids containing the HNTs through a capillary packed tightly with fresh and crude oil-saturated crushed shale cores. At 70 °C, the wax-coated surfactant-loaded halloysites system exhibited 40% oil recovery, compared to just 16% for surfactant alone and 3% for wax-coated halloysite (no surfactant). A much lower oil recovery for the surfactant alone (16%) can be attributed to excessive surfactant adsorption to the fresh core (85% adsorption), making these adsorbed surfactants unavailable to be in contact with the oil for enhancing the recovery. The method of surfactant encapsulation in wax-coated halloysites therefore leads to a targeted, stimulus-responsive delivery system to the oil–water interface in shale reservoirs with the potential to enhance oil recovery.Okhovat, M.R., Hassani, K., Rostami, B., Khosravi, M., 2020. Experimental studies of CO2-brine-rock interaction effects on permeability alteration during CO2-EOR. Journal of Petroleum Exploration and Production Technology 10, 2293-2301. dioxide (CO2) sequestration through CO2 enhanced oil recovery (EOR) in oil reservoirs is one way to reduce this gas in the atmosphere. Undesirable chemical reactions that occur during these operations can affect the reservoir structure and characteristics. In this study, the effect of CO2-water-rock interaction on the rock permeability alteration and final oil recovery has been evaluated experimentally during CO2 injection into a carbonate rock. The effect of flow rate, displacement type and pressure were investigated during CO2 EOR injection. Different scenarios of miscible/immiscible displacement, secondary/tertiary recovery has been evaluated for different levels of connate water salinity and injection rate. The results show that the severity of damage is directly related to the injection rate, however change in displacement type from miscible to immiscible reduce the intensity of chemical reactions in porous medium. Moreover, in the tertiary CO2 injection, the chemical reactions become more severe due to the higher water saturations. Interestingly, this growth in the level of chemical reactions has a negligible impact on permeability reduction, since the major volume of possible reactions occurs in coarse and high permeable pores. Results reveal that damage is more intense in the case of more saline water.Oliszewski, N., Galván, V.K., Srur, G., Olivera, D.E., Martínez, J.G., 2020. Human paleodiet studies between ca. 3300–1500?years BP in Quebrada de Los Corrales (Tucumán, Argentina). Journal of Archaeological Science: Reports 32, 102429. Quebrada de Los Corrales, located in northwestern Argentina, a local economic transitional process took place between ca. 3800 and 2000 BP, during which groups of hunter-gatherers incorporated agriculture and pastoralism. In this paper, we characterize the human diet in the period between 3300 and 1500?years BP using stable carbon isotope analysis on collagen and apatite as well as nitrogen. The application of a Bayesian mixing model allowed us to establish the dominant consumption of game meat and C3 plants. These results are the first obtained for the area and form an independent line of evidence for the process of socioeconomic change from societies of nomadic hunters towards societies of agro-pastoral villages. Thus, even when the number of individuals analyzed is low, they are archaeologically relevant as they represented the only pre-Hispanic funerary contexts detected in the study area so far.Oppenheimer, C., 2020. The sun of Rome is set! Volcanic dust veils and their political fallout. Proceedings of the National Academy of Sciences 117, 17470-17472. a year of the slaying of Julius Caesar, Okmok volcano in the Aleutian Islands (Fig. 1) begat one of the greatest eruptions of the past 2,500 y, according to research in PNAS (1). The study explores the repercussions of climatic change induced by the eruption for the unstable Roman Republic.Fig. 1. The 10-km-diameter caldera of Okmok volcano dominates the northeastern end of Umnak Island in the Aleutian archipelago. It was formed partly by a paroxysmal eruption now dated to early 43 BCE. Okmok’s last eruption was an explosive affair in 2008. Image credit: NASA Earth Observatory/Joshua Stevens, using Landsat data from the US Geological Survey.Since the 1991 eruption of Mt. Pinatubo, large eruptions have been widely recognized as a leading driver of natural climate variability (2?–4). Their study has also revealed many insights into the nature of magmatic processes of the Earth’s interior. However, lately, a renewed research focus on major volcanic episodes has been motivated by passion for world history.One of the first scientists to delve deep into this topic was the British meteorologist Hubert Lamb. In a landmark paper published in 1970, he formulated the dust veil index (DVI) to characterize the climate-forcing potential of volcanic eruptions, and compared his multicentennial time series of DVI values against climate proxies (5). What particularly interested Lamb were the influences of climatic change on societal trajectories, and his research laid the modern foundations of historical climatology (6). The importance of his work was quickly recognized by climate scientists, such as Stephen Schneider, who used the DVI in models to investigate the scale of climatic influence due to volcanism (7).In 1977, the economic historian John Post combined these themes of volcanism changing climate, and climatic change impacting society, in a compelling book with the provocative …Commentary on: McConnell et al. 2020. Extreme climate after massive eruption of Alaska’s Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic KingdomOrtega, R.P., 2020. Improbable oasis. Science 369, 20-25. in the Mexican desert are a hot spot of microbial diversity—and a window into early life.Valeria Souza Saldívar never planned to devote her life to a remote and ancient oasis more than 1000 kilometers north of her laboratory in Mexico City. But a call in early 1999 changed that.“It's one of the best cold calls I've ever made,” says James Elser, a limnologist at the University of Montana. He had picked up the phone to invite Souza Saldívar to join a NASA-funded astrobiology project in Cuatro Ciénegas—a butterfly-shaped basin with colorful pools, or pozas, in the middle of Mexico's Chihuahuan Desert.Neither Souza Saldívar, a microbial ecologist at the National Autonomous University of Mexico, University City, nor her ecologist husband and research partner Luis Eguiarte Fruns, also at UNAM, had ever visited Cuatro Ciénegas. That first trip convinced them to completely change their research plans. “Looking at those mountains and the water, I fell in love,” Souza Saldívar says.The landscape—more than 300 turquoise-blue pozas scattered across 800 square kilometers, among marshes and majestic mountains—wasn't the only draw. The waters, whose chemistry resembled that of Earth's ancient seas, teemed with microbes; unusual bacterial mats and formations called stromatolites carpeted the shallows. When Souza Saldívar first cultured the organisms from the pozas, “The amount of microbes was enormous, as was the diversity of colors and colony sizes,” she recalls. For her, this remote microbial hot spot was an irresistible mystery.Since then, work by Souza Saldívar, Eguiarte Fruns, and a widening circle of collaborators in Mexico and the United States has shown that Cuatro Ciénegas—which means “four marshes” in Spanish—is one of the most biodiverse places on the planet. “There's nowhere that has so much ancient diversity of microorganisms,” says Michael Travisano, an evolutionary ecologist at the University of Minnesota, Twin Cities, who has collaborated with the Mexican researchers since 2001. Among the most recent additions to that menagerie are hundreds of species of archaea, the ancient microbes that may have given rise to eukaryotes—organisms with complex, nucleated cells.The diversity includes strains with unusual adaptations, such as the ability to build their lipid membranes with sulfur instead of the usual phosphorus, which is scarce in the waters of the pozas. It includes potential sources of new compounds for medicine and agriculture. And it poses a question that has occupied Souza Saldívar and Eguiarte Fruns for the past 20 years: How did this Noah's Ark of ancient microbes arise? “It's a dream for every biologist to know the origin of diversification,” Souza Saldívar says.But her dream might be short-lived. Since the 1970s, farmers have intensively drained water from the pozas and rivers to irrigate nearby fields of alfalfa, grown for cattle fodder, gradually drying the improbable oasis. Souza Saldívar has galvanized a conservation effort that has slowed the drainage; in the coming weeks, a canal that removes 100 million cubic meters of Cuatro Ciénegas's water annually is scheduled to close. In the meantime, the researchers have been trying to describe as much as they can, as fast as they can, before their beloved pozas dry up and the precious microscopic life that has survived undisturbed for millions of years dies off.Cuatro Ciénegas served as a stopping point for hunter-gatherers for thousands of years. To date, 50 archaeological sites with cave paintings—some dating to 2275 B.C.E.—have been found in mountain caves around the basin. Much later, the region made a mark on history when Venustiano Carranza, born in a village at the basin's margin, became a leader of the Mexican Revolution and president of Mexico from 1917 to 1920. Nowadays, the village is called Cuatro Ciénegas de Carranza after him.But in the 1960s, Cuatro Ciénegas started to become famous for its biodiversity, as biologists began to describe new species of snails, fish, turtles, and plants found in the pools and marshes—and often nowhere else.Wendell “Minck” Minckley, a renowned ichthyologist at Arizona State University (ASU), Tempe, was first lured to Cuatro Ciénegas after learning that the world's only aquatic box turtle (Terrapene coahuila) lived there. Over the years, Minckley made frequent trips to the pozas, describing their snails and fish (Herichthys minckleyi, a cichlid, bears his name) while making connections with the local people.Minckley also noticed peculiar, rocky structures in the pools. They were stromatolites, biological structures normally found as fossils dating back as much as 3.5 billion years. Colonies of photosynthesizing bacteria, which boosted early Earth's oxygen, created the layered formations by depositing carbonates and trapping sediment in ancient, shallow seas. But these stromatolites were alive. Also found in other extreme environments such as Australia's warm, salty Shark Bay, living stromatolites “are sort of a window into early Earth,” Elser says. The pozas also nurture bacterial mats, a soft form of stromatolites normally found deep in the ocean.As early as the 1970s, Minckley realized the pools and their diversity were under threat: Local farmers were carving canals to tap their water. Thanks in part to his lobbying, the Mexican government in 1994 designated an 85,000-hectare protected area. But the drainage continued. “Minckley knew that Cuatro Ciénegas was going to die,” Souza Saldívar says. He thought NASA might be its salvation.In 1998, NASA established its Astrobiology Institute, a network of researchers studying life in extreme environments that might resemble conditions on other planets. Minckley saw an ideal astrobiology study site in the waters of the pozas, with their seemingly inhospitable chemistry and living stromatolites. But he was no expert on extreme environments, so he enlisted Elser, who specializes in how water chemistry affects ecosystems and also works at ASU. After they submitted a 1998 proposal to fund the project, however, NASA said they should add experts on microbiology and evolution—and those experts had to be Mexican to help secure permits to obtain samples. Based on colleagues' suggestions, Elser called Souza Saldívar and Eguiarte Fruns, newly minted professors at UNAM. They joined, and NASA approved the 3-year project.With two children in tow, the couple met Minckley and Elser at Cuatro Ciénegas. Next to the turquoise-blue waters of La Becerra poza, Minckley told them he believed the ecosystem was a glimpse of deep time. “Do you see these miniature snails in my hand?” Souza Saldívar recalls him saying. “I just scooped them from the springhead, but their direct ancestors were eating sulfur bacteria in hydrothermal vents 220 million years ago in the bottom of the ancient Pacific.”Based on the water chemistry—low in phosphorus, iron, and nitrogen—and the presence of living stromatolites, Minckley believed Cuatro Ciénegas re-created the marine conditions found worldwide millions of years ago. He challenged the two researchers to explore its mysteries—and to protect its pozas. “Only you, as Mexicans, can save them from the extinction caused by humans,” Souza Saldívar recalls him saying.Minckley died 2 years later, in 2001.To inventory the full diversity of microbes at Cuatro Ciénegas and trace their relationships, Souza Saldívar needed to study their DNA. To do so, scientists normally take microbial samples from a site and grow them in a lab. But many bacteria and archaea are difficult to culture, and only a few groups at the time had successfully analyzed DNA isolated directly from the environment. High magnesium levels in the water and “slime” from the microbes made isolating DNA from the pozas especially difficult.But Souza Saldívar and her students Ana Escalante and Laura Espinosa Asuar made a start. In 2006, they reported in the Proceedings of the National Academy of Sciences that they had found 38 distinct groups of microbes—four times as many as in a typical salt marsh—corresponding to 10 major lineages of bacteria and one of archaea. Half the bacterial groups were most closely related to marine microbes. Almost 10% of the groups resembled ones that live on hydrothermal vents—fissures deep in the ocean where microbes thrive despite extreme heat and mineral concentrations.As Minckley had suspected, Cuatro Ciénegas had somehow preserved ancient marine life forms deep in the desert, more than 500 kilometers from the Gulf of Mexico, at a site where the last seas retreated some 20 million years ago.Ovsyuchenko, A.N., Larkov, A.S., Sysolin, A.I., Rogozhin, E.A., Sobisevich, A.L., Chen, J., Liu, J., Qin, J., 2020. Recent tectonic rupturing on the mud volcano of Mount Karabetova, Taman Peninsula. Doklady Earth Sciences 492, 361-365. October 2019, extremely impressive, fresh ruptures of the surface on the mud volcano of Mount Karabetova were discovered. The ruptures are represented by all the main kinematic types and demonstrate structural patterns that are characteristic of typically tectonic deformations. The total length of the ruptures from south to north is slightly less than 600 m. Repeated measurements showed high displacement rates ranging from 50 to 140 cm in three months. The fresh ruptures marked the further development of more ancient similar landforms. They are caused by the existing structure and can be interpreted as potentially hazardous objects on other mud volcanoes. It can be assumed that ruptures may result from increased pressure in the mud volcano chamber and can be a forecasting indication of an upcoming eruption.Padoan, S., Zappi, A., Adam, T., Melucci, D., Gambaro, A., Formenton, G., Popovicheva, O., Nguyen, D.-L., Schnelle-Kreis, J., Zimmermann, R., 2020. Organic molecular markers and source contributions in a polluted municipality of north-east Italy: Extended PCA-PMF statistical approach. Environmental Research 186, 109587. the maximum levels for environmental pollutants creates public and scientific interest for the environmental and human health impact it may have. In Northern Italy, the Po Valley, and in particular the Veneto region, is still a hotspot for air quality improvement. Several monitoring campaigns were carried out in this area to acquire information about sources of pollutants which are considered critical. For the first time, a deep study of the aerosol organic fraction was performed in the town Sernaglia della Battaglia, nearby Treviso. During three seasons of 2017, PM1 and PM2.5 samples were collected simultaneously. Organic molecular markers have been analyzed by in-situ derivatization thermal desorption gas chromatography time-of-flight mass spectrometry (IDTD-GC-TOFMS). Alkanes, polycyclic aromatic hydrocarbons, oxi-polycyclic aromatic hydrocarbons, anhydrous sugars, resins acids, triterpenoids, and acids were considered. The organic chemical composition has been analyzed based on seasonal variation and source contributions. Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF) have been combined to deeply investigate the main sources of particulate organic matter. On the one hand, PCA evaluates the correlations between the organic markers and their seasonal distribution. On the other hand, the source contributions to aerosol composition are estimated by PMF. Four main emission sources were found by PMF: solid fuel combustion (coal, wood), combustion of petroleum distillates (gas and fuel oil) and exhaust gases of vehicles, industrial combustion processes, home heating, and forest fires are evaluated as the most important sources for the air quality and pollution in this municipality of Northern Italy.Palin, R.M., Santosh, M., Cao, W., Li, S.-S., Hernández-Uribe, D., Parsons, A., 2020. Secular change and the onset of plate tectonics on Earth. Earth-Science Reviews 207, 103172. Earth as a planetary system has experienced significant change since its formation c. 4.54 Gyr ago. Some of these changes have been gradual, such as secular cooling of the mantle, and some have been abrupt, such as the rapid increase in free oxygen in the atmosphere at the Archean–Proterozoic transition. Many of these changes have directly affected tectonic processes on Earth and are manifest by temporal trends within the sedimentary, igneous, and metamorphic rock record. Indeed, the timing of global onset of mobile-lid (subduction-driven) plate tectonics on our planet remains one of the fundamental points of debate within the geosciences today, and constraining the age and cause of this transition has profound implications for understanding our own planet's long-term evolution, and that for other rocky bodies in our solar system. Interpretations based on various sources of evidence have led different authors to propose a very wide range of ages for the onset of subduction-driven tectonics, which span almost all of Earth history from the Hadean to the Neoproterozoic, with this uncertainty stemming from the varying reliability of different proxies. Here, we review evidence for paleo-subduction preserved within the geological record, with a focus on metamorphic rocks and the geodynamic information that can be derived from them. First, we describe the different types of tectonic/geodynamic regimes that may occur on Earth or any other silicate body, and then review different models for the thermal evolution of the Earth and the geodynamic conditions necessary for plate tectonics to stabilize on a rocky planet. The community's current understanding of the petrology and structure of Archean and Proterozoic oceanic and continental crust is then discussed in comparison with modern-day equivalents, including how and why they differ. We then summarize evidence for the operation of subduction through time, including petrological (metamorphic), tectonic, and geochemical/isotopic data, and the results of petrological and geodynamical modeling. The styles of metamorphism in the Archean are then examined and we discuss how the secular distribution of metamorphic rock types can inform the type of geodynamic regime that operated at any point in time. In conclusion, we argue that most independent observations from the geological record and results of lithospheric-scale geodynamic modeling support a global-scale initiation of plate tectonics no later than c. 3 Ga, just preceding the Archean–Proterozoic transition. Evidence for subduction in Early Archean terranes is likely accounted for by localized occurrences of plume-induced subduction initiation, although these did not develop into a stable, globally connected network of plate boundaries until later in Earth history. Finally, we provide a discussion of major unresolved questions related to this review's theme and provide suggested directions for future research.Paris, G., Fischer, W.W., Johnson, J.E., Webb, S.M., Present, T.M., Sessions, A.L., Adkins, J.F., 2020. Deposition of sulfate aerosols with positive Δ33S in the Neoarchean. Geochimica et Cosmochimica Acta 285, 1-20. sulfur isotope compositions present in Archean rocks have been intensely scrutinized over the last 20?years because they record key aspects of Earth's atmospheric composition prior to the appearance of free molecular oxygen ca. 2.3 billion years ago. These isotopic compositions can be described as mass anomalous fractionations (MAF) and are produced in the atmosphere as UV light interacts with SO2 molecules. Most interpretations suggest that atmospheric processes generate a reduced S-phase with a positive (33S-enriched) MAF signature, as measured in pyrites, and an oxidized S-phase with a negative anomaly, as measured in bedded barite deposits. However, recent data for carbonate-associated sulfate (CAS) — a direct proxy for the isotopic composition of sulfur from seawater sulfate — in Neoarchean rocks showed no such negative values, but rather the opposite. To understand if the positive MAF anomalies we measured in Neoarchean CAS reflect secondary processes (diagenetic, metamorphic, handling) instead of original signals of Archean seawater sulfate, we collected additional sample suites with various degrees of preservation and metamorphic alteration across the Campbellrand-Malmani platform in South Africa. Results illustrate that within this comprehensive suite, less-altered samples all contain positive MAF values while secondary processes tend to either remove CAS from the sample and/or decrease the 33S-enrichment. This positive MAF signal in sulfate is therefore reasonably interpreted as a primary depositional origin, and implies that the assumption that sulfate always carries a negative MAF anomaly throughout the Archean rock record needs to be reconsidered. Our CAS observations suggest that future experiments and calculations should also consider atmospheric and/or sulfur cycling processes that can produce oxidized sulfur with a positive MAF signature.Park, H., Choi, I.-G., 2020. Genomic and transcriptomic perspectives on mycoremediation of polycyclic aromatic hydrocarbons. Applied Microbiology and Biotechnology 104, 6919-6928. holds great potential in remedying toxic environments contaminated with polyaromatic organic pollutants. To harness the natural process for practical applications, understanding the genetic and molecular basis of the remediation process is prerequisite. Compared to known bacterial degradation pathways of aromatic pollutants, however, the fungal degradation system is less studied and understanding of the genetic basis for biochemical activity is still incomplete. In this review, we surveyed recent findings from genomic and transcriptomic approaches to mycoremediation of aromatic pollutants, in company with the genomic basis of polycyclic aromatic hydrocarbon (PAH) degradation by basidiomycete fungi, Dentipellis sp. KUC8613. Unique features in the fungal degradation of PAHs were outlined by multiple cellular processes: (i) the initial oxidation of recalcitrant contaminants by various oxidoreductases including mono- and dioxygenases, (ii) the following detoxification, and (iii) the mineralization of activated pollutants that are common metabolism in many fungi. Along with the genomic data, the transcriptomic analysis not only posits a full repertoire of inducible genes that are common or specific to metabolize different PAHs but also leads to the discovery of uncharacterized genes with potential functions for bioremediation processes. In addition, the metagenomic study accesses community level of mycoremediation process to seek for the potential species or a microbial consortium in the natural environments. The comprehensive understanding of fungal degradation in multiple levels will accelerate practical application of mycoremediation.Patel, S.K.S., Gupta, R.K., Kondaveeti, S., Otari, S.V., Kumar, A., Kalia, V.C., Lee, J.-K., 2020. Conversion of biogas to methanol by methanotrophs immobilized on chemically modified chitosan. Bioresource Technology 315, 123791. this study, chitosan modified with glutaraldehyde (GLA), 3-aminopropyltriethoxysilane (APTES), polyethyleneimine, and APTES followed by GLA (APTES-GLA) as a support material was used to improve methanol production from biogas. Among these support materials, chitosan-APTES-GLA showed the highest increase in immobilization yield and relative efficiency of Methylomicrobium album up to 56.4% and 97.7%, respectively. Maximum cell loading of 236 mg dry cell mass per g-support was observed for M. album., which is 7.7-fold higher than that of chitosan. The immobilized M. album maintained a 23.9-fold higher methanol production compared to free cells after 8 cycles of reuse; it also produced 6.92 mmol·L?1 methanol from biogas that originated from anaerobic digestion of rice straw, thereby validating its industrial application. This is the first report on the immobilization of methanotrophs on chemically modified chitosans to improve cell loading and relative efficiency, and its potential applications in the conversion of greenhouse gases to methanol.Patricia, G.R.O., Blandón, A., Perea, C., Mastalerz, M., 2020. Petrographic characterization, variations in chemistry, and paleoenvironmental interpretation of Colombian coals. International Journal of Coal Geology 227, 103516. study focuses on variations in petrographic composition and chemistry of macerals from different coalfields in Colombia. The coal-bearing formations in Colombia occur in the age interval from the Maastrichtian in the Upper Cretaceous to the Paleogene and Neogene (Paleocene, Eocene, Oligocene, and Late Pliocene) up to Early Pleistocene. The coals range in rank from lignite to semianthracite. Petrographically, the coal is composed dominantly of macerals of the vitrinite group (>50% by volume). The coals from the regions of Antioquia, Córdoba, and Caldas are characterized by relatively high proportions of liptinite (up to 30 vol%). The inertinite contents vary up to 30 vol%, and the coals from the regions of Boyacá and Guajira contain the highest quantities of this maceral group. The Colombian coals studied have low moisture, except for the coal from Caldas being lignite type A. The sulfur content ranges between 0.28 weigh % in coal from Guajira to slightly above 2% in coal from Córdoba and Cauca.The coal facies diagrams suggest that palaeomires developed mostly under limno-telmatic to wet forest mire conditions. The ratios of microlithotypes suggest that the original peat mires evolved under fluvial, upper deltaic and brackish settings. Overall coal petrography data suggest that peat-forming vegetation and water tables in palaeomires experienced significant variations between the Upper Maastrichtian to Pliocene - Early Pleistocene period.Variations in chemistry of coal macerals reflect to large extent the coal rank variations. Specifically, with the increase in vitrinite reflectance (Ro), the contents of aliphatic functional groups decrease whereas those of the aromatic groups increase. The values of CH2/CH3 ratios also decrease with increasing coal rank (2.24 in Boyacá and 0.97 in Cauca). Expectedly, spectral differences between individual macerals are most distinct in the low rank coals (0.48% Ro).Peace, A.L., Phethean, J.J.J., Franke, D., Foulger, G.R., Schiffer, C., Welford, J.K., McHone, G., Rocchi, S., Schnabel, M., Doré, A.G., 2020. A review of Pangaea dispersal and Large Igneous Provinces – In search of a causative mechanism. Earth-Science Reviews 206, 102902. breakup of Pangaea was accompanied by extensive, episodic, magmatic activity. Several Large Igneous Provinces (LIPs) formed, such as the Central Atlantic Magmatic Province (CAMP) and the North Atlantic Igneous Province (NAIP). Here, we review the chronology of Pangaea breakup and related large-scale magmatism. We review the Triassic formation of the Central Atlantic Ocean, the breakup between East and West Gondwana in the Middle Jurassic, the Early Cretaceous opening of the South Atlantic, the Cretaceous separation of India from Antarctica, and finally the formation of the North Atlantic in the Mesozoic-Cenozoic. We demonstrate that throughout the dispersal of Pangaea, major volcanism typically occurs distal from the locus of rift initiation and initial oceanic crust accretion. There is no location where extension propagates away from a newly formed LIP. Instead, LIPs are coincident with major lithosphere-scale shear movements, aborted rifts and splinters of continental crust rifted far out into the oceanic domain. These observations suggest that a fundamental reappraisal of the causes and consequences of breakup-related LIPs is in order.Pe?a, V., Vieira, C., Braga, J.C., Aguirre, J., R?sler, A., Baele, G., De Clerck, O., Le Gall, L., 2020. Radiation of the coralline red algae (Corallinophycidae, Rhodophyta) crown group as inferred from a multilocus time-calibrated phylogeny. Molecular Phylogenetics and Evolution 150, 106845. subclass Corallinophycidae is the only group of red algae characterized by the presence of calcite crystals in their cell walls. Except for the Rhodogorgonales, the remaining orders - collectively called corallines - are diverse and widely distributed, having calcified cell walls and highly variable morphology. Corallines constitute the group with the richest fossil record among marine algae. In the present study, we investigate the evolutionary history of the subclass Corallinophycidae and provide a time-calibrated phylogeny to date the radiation of the crown group and its main lineages. We use a multi-locus dataset with an extensive taxon sampling and comprehensive collection of fossil records, carefully assigned to corallines, to reconstruct a time-calibrated phylogeny of this subclass. Our molecular clock analyses suggest that the onset of crown group diversification of Corallinophycidae started in the Lower Jurassic and sped up in the Lower Cretaceous. The divergence time of the oldest order Sporolithales is estimated in the Lower Cretaceous followed by the remaining orders. We discuss the long period of more than 300 million years between the early Paleozoic records attributed to the stem group of Corallinophycidae and the radiation of the crown group. Our inferred phylogeny yields three highly-supported suprageneric lineages for the order Corallinales; we confirm the family Mastophoraceae and amend circumscription of the families Corallinaceae and Lithophyllaceae. These three families are distinguished by a combination of vegetative and reproductive features. In light of the phylogeny, we discuss the evolutionary trends of eleven morphological characters. In addition, we also highlight homoplasious characters and selected autapomorphies emerging in particular taxa.Peng, J., Milliken, K.L., Fu, Q., Janson, X., Hamlin, H.S., 2020. Grain assemblages and diagenesis in organic-rich mudrocks, Upper Pennsylvanian Cline shale (Wolfcamp D), Midland Basin, Texas. American Association of Petroleum Geologists Bulletin 104, 1593-1624. assemblages in the organic-rich Cline shale in the Midland Basin are dominated by components of extrabasinal derivation (11.4 to 98.5 vol. %; average volume: 82.6%). Major extrabasinal components include K-rich clay minerals, detrital quartz, albite, K-feldspar, micas, and lithic fragments. Intrabasinal components include mainly biosiliceous allochems (sponge spicules and radiolarians), agglutinated foraminifera, Ca-phosphate peloids, clay-rich peloids, organomineralic aggregates, intraclasts, and other biocalcareous allochems. Authigenic minerals are most evident as grain replacements, euhedral ankerite, Ca-phosphate cement, and precipitates in large pores. A strongly localized spatial distribution of diagenetic products at micron to centimeter scales is observed in most siliciclastic samples, except in biosiliceous allochem-rich ones in which abundant intergranular pore-filling clay-size microquartz cement is observed. Compaction is evident in the Cline shale because of low porosity and generally low cement volumes. Neither textural variation nor bulk mineral composition alone is sufficient to confidently decipher the rock bulk property (e.g., total organic carbon) and reservoir quality variation (e.g., porosity and permeability). However, a good negative relationship between the ratio of extrabasinal to intrabasinal grains and favorable reservoir properties is observed in the Cline shale. Specifically, higher porosity, permeability, and total organic carbon are observed in samples representing the extreme end members of intrabasinal-derived biosilica-rich layers. Nickel, a recognized proxy for paleoproductivity, exhibits a positive relationship with intrabasinal grain content and reservoir properties. X-ray fluorescence–based analysis of nickel can be a rapid and cost-effective way to delineate favorable unconventional reservoir quality in the Cline shale.Peng, X., Guo, Z., Du, M., Czaja, A.D., Papineau, D., Chen, S., Xu, H., Li, J., Ta, K., Bai, S., Dasgupta, S., 2020. Past endolithic life in metamorphic ocean crust. Geochemical Perspectives Letters 14, 14-19. known deep subsurface biosphere on Earth persists in diversified habitats, including deep within igneous rocks of the oceanic crust. Here, we extend the range of the deep subsurface biosphere to metamorphic ocean crust of a subduction zone. We report fossilised life in zeolite facies rocks, which formed by low grade metamorphism, from the southern Mariana trench. Dense carbonaceous spheroids, filaments, and Frutexites-like structures are preserved in these rocks, which are enriched in organic carbon but depleted in 13C. The distinct difference in the GDGT-0 vs. crenarchaeol and the branched vs. isoprenoid tetraether values between the inner and outer portions of these rocks indicate the in situ production of organic carbon. We demonstrate that these structures may result from the past activity of potential chemolithoautotrophs within the metamorphic crust, as implied by their morphologies, Raman spectra, carbon isotopes, and biomarker signatures, as well as the Fe oxidation state within whole rocks. We propose that fluid-rock reactions at temperatures within the tolerance of life during low grade metamorphism contributed to microbial subsistence within the biotope. The low grade metamorphic ocean crust of the subduction zone likely represents Earth’s deepest, and one of its largest, microbial ecosystems, which may potentially influence the deep carbon cycle. Peng, Y., Dong, L., Ma, H., Wang, R., Lang, X., Peng, Y., Qin, S., Liu, W., Shen, B., 2020. Surface ocean nitrate-limitation in the aftermath of Marinoan snowball Earth: Evidence from the Ediacaran Doushantuo Formation in the western margin of the Yangtze Block, South China. Precambrian Research 347, 105846. and paleontological studies suggest that a rapid rise in atmospheric O2 level in the termination of the Marinoan global glaciation (635 Ma) might have triggered the diversification of eukaryotes and caused the deep ocean oxygenation. It is proposed that the Earth’s surface redox condition was directly linked to the marine primary productivity, which represented the only major O2 source before the evolution of land plants. The marine primary productivity was mainly controlled by the bioavailability of macronutrients, phosphorus (P) and nitrogen (N). Thus, reconstruction of ancient P and N cycles can provide direct constraints on marine organic matter production and the redox landscape of the ocean. Previous studies of the Ediacaran Doushantuo Formation in the Yangtze Block, South China, suggested that the Ediacaran marine N cycle was highly dynamic and was characterized by dramatic fluctuations in the intensity of denitrification. However, these studies were mainly focused on sections deposited in the offshore marine environment, and little is known about the N cycle in the nearshore regions. In this study, we report high-resolution organic carbon (δ13Corg) and nitrogen (δ15NTN) isotopes of the Doushantuo Formation at the E-Shan section in the western margin of the Yangtze Block. The Doushantuo Formation at the E-Shan section is composed of alternating deposition of thin bedded sandstone and mudstone, and was deposited in a nearshore delta environment. The δ13Corg profile displays two prominent negative excursions, which are coincident with two positive excursions in δ15NTN. The positive excursion in δ15NTN implies the enhanced denitrification, resulting in the loss of N (nitrate and ammonium). In addition, there are negative correlations between δ15NTN and TOC content and between δ15NTN and δ13Corg. Such relationships suggest that the reduction of N supply would lower primary productivity and accordingly decrease the carbon isotope of dissolved inorganic carbon (δ13CDIC) in the surface ocean. In addition, this interpretation also implies that N-fixation was not active in the nearshore region. We speculate that the muted N-fixation in the nearshore regions could be attributed to the Fe limitation in oxic shallow seawater and general Mo deficiency of the Ediacaran ocean. Thus, our study indicates that the surface ocean productivity and marine redox landscape were coupled in the Ediacaran ocean.Perkins, S., 2020. Core Concept: Lava tubes may be havens for ancient alien life and future human explorers. Proceedings of the National Academy of Sciences 117, 17461-17464., there’s more to a lava flow than meets the eye. Beneath a fresh, sterile, and steaming hot surface, molten rock can still be chewing its way into the ground, carving caves that can stretch dozens of kilometers. On Earth, such lava tubes (once cooled) are a challenge for spelunkers. On the moon and Mars, these features are piquing the interest of planetary geologists, astrobiologists, and explorers.Besides providing a window into geological history, lava tubes offer environmental conditions that are relatively stable and likely to be more hospitable than those found on a planet’s surface. This may make the tubes appealing to life-forms of all sizes, from microbes to spacefaring colonists from Earth.If Mars ever hosted life, it may have moved into such refugia as the planet evolved and surface conditions became increasingly harsh. Indeed, some researchers suggest that microbial life may yet hang on in the Red Planet’s underground havens. “On Mars and other places, lava tubes have the potential to have made the difference between life and death,” says Pascal Lee, a planetary researcher at NASA Ames Research Center in Mountain View, CA.Wherever lava tubes are found, they’ll be scientifically exotic, says Lee. And if a mission to another world is designed to explore such an underground feature as well as the surface, “it’ll be like getting two planets for the price of one,” he notes.Grow With the Flow: Lava tubes can form almost anywhere molten rock streams from the ground. Steady flows of low-viscosity lava are the most likely to form lava tubes. They can form in a way akin to how rivers ice over during a cold spell. As flowing lava loses heat to the overlying air, its surface cools and solidifies—but it does so more quickly at the edges of the flow, where material moves slowly. Eventually, the molten flow freezes over from shore to shore, which insulates the underlying lava by robbing it of the ability to directly radiate heat upward or be cooled by winds, he explains. Then, when the source of lava begins to wane or as the molten flow chews or melts its way into the underlying rocks, or both, lava drains from the conduit and leaves behind a smooth-sided, steep-walled cavern.Lava flows can melt their way into underlying rocks. If the flow is fast and turbulent, lava can erode downward as much as 1 meter each day, according to Alan Whittington, a geologist at University of Texas San Antonio, speaking at the Third International Planetary Caves Conference in San Antonio, TX, in February (1). So the tubes created by voluminous and long-lived flows can be huge. The longest known lava tube on Earth—65-kilometer-long Kazumura Cave, on the Big Island of Hawaii—stretches almost to the sea from the Kilauea volcano. In some spots, the tube measures 21 meters wide and 18 meters tall (2)—a profile big enough to hold a good-sized house.But lava tubes on the moon and Mars are almost certainly bigger. Most of these features likely date from 3 to 4 billion years ago, when both bodies had frequent volcanic activity. Grooved features known as sinuous rilles have long been suspected to be collapsed lava tubes; and more recently, stronger evidence has emerged. Images snapped by orbiting probes show openings into underground voids. Often referred to as skylights, these openings probably formed when the roofs of lava tubes fell in. The first such feature on the moon—a hole 50 meters across and dozens of meters deep—was discovered more than a decade ago in an image captured by Japan’s SELENE orbiter (3). Many more skylights have been found on the moon since then, and hundreds of possible skylights have been spotted on images snapped by Mars orbiters, the first of which were taken in the mid-1970s (4).Earth’s lava tubes range in age from a few years old, such as those on the slopes of Hawaii’s Kilauea volcano, to a few hundred thousand years or more. The freshest tubes have yet to be mapped, but in some areas they’re known to stretch dozens of kilometers. In California’s Lava Beds National Monument, for example, more than 800 lava tubes together extend at least 350 kilometers.Habitat for Humanity? Researchers have for decades speculated that lava tubes on the moon and elsewhere could offer prime space for setting up living quarters for colonists (5). The tubes are appealing for many reasons, as Laura Kerber, a geologist at NASA’s Jet Propulsion Laboratory in Pasadena, CA, explained at the caves conference (6). First, the environment is protected from radiation such as cosmic rays, solar energetic particles, and ultraviolet light. Second, the rock roof would be a shield against micrometeorites that could otherwise puncture spacesuits and buildings. And as on Earth, the underground environment would be buffered from temperature swings. On the moon, those variations are extreme. Data gathered by the Lunar Reconnaissance Orbiter between 2009 and 2013 reveal that temperatures near the lunar equator can reach 120 °C in the daytime and plunge to –130 °C during the two-week-long night.Whether colonists could actually take advantage of those benefits is another question. Considering the likely instability of material around the edges of skylights, as well as the limited mobility of existing spacesuits, it would be a big challenge to lower people into a hole in the ground and then get them back out, says Whittington. Then there’s the question of whether lava tubes are safe, says NASA’s Lee. Despite what he describes as the romantic idea of making a home in these features, “the truth about caves is that they’re dangerous,” he says. That’s especially likely to be true near skylights, where the roof has already demonstrated the propensity to collapse. Human activity could well destabilize them even further, or cause avalanches of material around the edges of the skylights. “Lava tubes may be exciting to explore but not that safe to live in,” Lee says.Holes without Drilling: Whether or not lava tubes provide homes for pioneering lunar colonists, they’ll provide plenty of opportunities for geological research. As Charity Phillips-Lander, an astrobiologist at Southwest Research Institute in San Antonio, TX, remarked at the Planetary Caves conference, “caves provide access to the subsurface without the added weight of a drilling payload.”Apollo astronauts, as part of their rock- and soil-collecting activities on the lunar surface, never drilled more than 2.9 meters into the surface. In contrast, the walls of lunar skylights can measure tens of meters thick and show distinct layers. Some of those layers may be ancient lava flows that could be dated to show when and how often volcanic activity occurred, Kerber notes. Sandwiched between those strata may be layers of regolith, or pulverized rock, formed by the incessant pounding of meteorite impacts. The thickness of such layers may help researchers estimate the rates at which such impacts occurred in the past. The rates and timing of such impacts would be roughly the same as those Earth experienced, so they may shed light on the planet’s environment as life emerged—and whether it was snuffed out before emerging again. Moreover, detailed chemical analyses of those materials may reveal information about past variations in the solar wind, whose charged particles become trapped in the regolith. Tracing the history of the solar wind could also shed light on variations in Earth’s ancient climate. For one thing, a more active sun may have emitted more planet-warming radiation along with torrents of charged particles.Kerber and her colleagues have come up with an idea for how to reach those skylight strata: a lunar rover that deploys a rappelling robot whose wheels are chock full of instruments and sensors (7, 8). After approaching the skylight as close as researchers dare—slopes near the hole consist of loose material and can be as steep as 20°—the rover pays out the yo-yo-bot on a 300-meter-long tether that carries power and communications. As currently conceived, those instruments include a trio of high-resolution cameras, a microscope that gathers images at various wavelengths, and a spectrometer to chemically analyze minerals. Other tools include a small grinder to remove surface patina and expose bare rock.One big constraint on such a mission would be time, Kerber notes. The lander would need to set down on the moon, deploy its rover, and conduct its analyses all within the span of about 14 days, the length of time between lunar sunrise and sunset. That’s because the exceptionally frigid conditions of the lunar night could wreak havoc on fragile electronics, sensors, and batteries, making it unknown whether the equipment would “wake up” when the next dawn arrived.Martian Haven: The discovery of minerals formed by water, along with other data gathered by orbiting probes, landers, and rovers, suggest that billions of years ago Mars was warmer, wetter, and had a thicker atmosphere than it does today. If life ever evolved on the Red Planet, and if it was anything like life on Earth, it wouldn’t be living on the Mars surface today, says Lee. Besides being cold and arid, the surface is exposed to high amounts of ultraviolet radiation. The lack of a strong magnetic field means that cosmic rays and energetic particles from the sun are free to stream down, adding to the radiation hazard. Static electricity in the planet’s fierce dust storms helps create reactive chemicals called perchlorates that are toxic to any Earthlike life.But when you look at the subsurface, all of a sudden a lot of these problems go away,” Lee notes. Phillips-Lander agrees: “If life exists there, or existed there in the past, it probably will be best maintained in the subsurface, away from harsh surface conditions and processes.”Just as they do on the moon and Earth, lava tubes on Mars could provide a relatively stable environment. And even if that environment isn’t amenable for life today, it could have been life’s last holdout on a dying planet. At a time when large extraterrestrial impacts were more common, lava tubes could also have sheltered life from many of their devastating effects (9).So, one of NASA’s goals should be to determine whether there are any bioindicators—signs of past or present life—in Martian lava tubes (10), Phillips-Lander proposed at the caves conference. Such signs could include organic chemicals, which might fluoresce under certain wavelengths of light. Or they could be visible remnants of biofilms created by communities of microbes. Or if such obvious signs of life are absent, other signs of past life— such as fossilized microbial filaments or even fossil cells—could show up within minerals that formed on cave walls and were then preserved (11), says Michael Spilde, a mineralogist at the University of New Mexico in Albuquerque.Exploring lava tubes on the moon and Mars might yield information not only about those bodies and their impact histories but also about the Earth and the Sun. These features, says Kerber, would be “like a time capsule for early solar system history.”References1. A. G. Whittington, A. Sehlke, A. A. Morrison, Tubular hells: New measurements of lunar magma rheology and thermal properties applied to thermal erosion and lava tube formation. Presentation #1077 at the Third International Planetary Caves Conference. . K. Allred, C. Allred, Development and morphology of Kazumura Cave, Hawaii. Journal of Karst and Cave Studies 59, 67–80 (1997).3. J. Haruyama et al., Possible lunar lava tube skylight observed by SELENE cameras. Geophys. Res. Lett. 36 (L21206), 1–5 (2009).4. U.S. Geological Survey, The caves of Mars. . Accessed 22 April 2020.5. C. R. Coombs, B. R. Hawke, “A search for intact lava tubes on the moon: Possible lunar base habitats” in Proceedings of the Second Conference on Lunar Bases and Space Activities of the 21st Century, W.W. Mendell Ed. (NASA, Johnson Space Center, Houston, 1992), p. 219.6. I. Kerber, The state of extraterrestrial cave science and exploration. Plenary lecture at the Third International Planetary Caves Conference. . 7. I. A. Nesnas et al., Moon diver: A discovery mission concept for understanding the history of secondary crusts through the exploration of a lunar mare pit. Presentation at the IEEE Aerospace Conference AERO 2019. . L. Kerber et al., Moon Diver: Journey into the ancient lavas of the moon. Presentation #1049 at the Third International Planetary Caves Conference. . P. J. Boston, Cavities and caves throughout the solar system: Prospects revisited for occurrence and astrobiological significance. Presentation #1076 at the Third International Planetary Caves Conference. . 10. C. M. Phillips-Lander et al., Science returns expected from MACIE: Mars Astrobiological Caves and Internal Habitability Explorer (a New Frontiers mission concept). Presentation #1042 at the Third International Planetary Caves Conference. . 11. M. N. Spilde et al., Mineral biomarkers for extraterrestrial caves. Presentation #1071 at the Third International Planetary Caves Conference. Petryshyn, V.A., Greene, S.E., Farnsworth, A., Lunt, D.J., Kelley, A., Gammariello, R., Ibarra, Y., Bottjer, D.J., Tripati, A., Corsetti, F.A., 2020. The role of temperature in the initiation of the end-Triassic mass extinction. Earth-Science Reviews 208, 103266. end-Triassic mass extinction coincided with the eruption of the Central Atlantic Magmatic Province, a large igneous province responsible for the massive atmospheric input of potentially climate-altering volatile compounds that is associated with a sharp rise in atmospheric CO2. The extinction mechanism is debated, but both short-term cooling (~10s of years) related to sulfur aerosols and longer-term warming (10,000 yrs) related to CO2 emissions—essentially opposite hypotheses—are suggested triggers. Until now, no temperature records spanning this crucial interval were available to provide a baseline or to differentiate between hypothesized mechanisms. Here, we use clumped-isotope paleothermometry of shallow marine microbialites coupled with climate modeling to reconstruct ocean temperature at the extinction horizon. We find mild to warm ocean temperatures during the extinction event and evidence for repeated temperature swings of ~16 °C, which we interpret as a signature of strong seasonality. These results constitute the oldest non-biomineralized marine seasonal temperature record. We resolve no apparent evidence for short-term cooling or initial warming across the 1-80kyr of the extinction event our record captures, implying that the initial onset of the biodiversity crisis may necessitate another mechanism.Pillai, S.S.K., Mathews, R.P., Murthy, S., Goswami, S., Agrawal, S., Sahoo, M., Singh, R.K., 2020. Palaeofloral investigation based on morphotaxonomy, palynomorphs, biomarkers and stable isotope from Lalmatia coal mine of Rajmahal Lower Gondwana Basin, Godda District, Jharkhand: An inclusive empirical study. Journal of the Geological Society of India 96, 43-57. rich Glossopteris dominated plant fossils assemblage is recovered from the Barakar Formation of Lalmatia coal mine, Hura coalfield of Rajmahal Basin, Godda district, Jharkhand, India. The assemblage includes Glossopteris, Gangamopteris and Noeggerathiopsis (leaf forms) along with Vertebraria (root form). There are 4 genera and 14 species of megafossils in the collection, which includes 10 species of Glossopteris, two species of Gangamopteris and one species of Noeggerathiopsis and Vertebraria each. The flora, although similar to that of the Barakar Formation of the Damodar Basin complex, exhibit unique characteristics and is of Artinskian to Kungurian in age. The palynoassemblage recovered in the section reveals the dominance of genus Scheuringipollenites and sub-dominance of Faunipollenites (=Protohaploxypinus) along with Parasaccites, Potonieisporites, Barakarites, Plicatipollenites, Striomonosaccites, Striatopodocarpites, Crescentipollenites, Verticipollenites, Rhizomaspora, Distriatites, Primuspollenites, Striasulcites, Lunatisporites, Guttulapollenites, Platysaccus, Microfoveolatispora, Microbaculispora, Horriditriletes, Tiwariasporis and Weylandites, which demonstrates an early Permian age (Artinskian). The palynoassemblage indicates that the sediments belong to the lower part of the Barakar Formation. Biomarker analysis suggests varying organic matter input during the deposition of the studied sequence. Diterpane compounds and megafossil evidences suggest Glossopteris were the dominant flora along with conifers. Bacterial alteration of the organic matter is inferred from the hopane compounds. The δ13C value of organic matter associated with the carbonaceous shale directly corroborates with the typical δ13C values of the Permian time and is suggestive of warm and humid climatic conditions.Ping, H., Chen, H., George, S.C., 2020. Quantitatively predicting the thermal maturity of oil trapped in fluid inclusions based on fluorescence and molecular geochemical data of oil inclusions in the Dongying depression, Bohai Bay Basin, China. American Association of Petroleum Geologists Bulletin 104, 1751-1791. fluorescence characteristics of individual oil inclusions and molecular composition analysis of oil inclusions in 20 Eocene sandstone samples from the Dongying depression were used to assess the relationship between the fluorescence colors of the oil inclusions and their thermal maturity. The oil inclusions from the Shahejie Formation member III middle submember, member III lower submember, and member IV upper submember samples primarily have yellow fluorescence colors (500 nm < wavelength of the maximum intensity (λmax) < 590 nm), whereas the oil inclusions in the Shahejie Formation member IV lower submember reservoir sample only have blue fluorescence (440 nm < λmax < 500 nm). The molecular maturity parameters from steranes, hopanes, and aromatic hydrocarbons showed that the oil inclusions with yellow fluorescence colors have relatively low thermal maturities within a narrow range (0.75%–0.82% vitrinite reflectance equivalent [Requ]), which is significantly lower than that of the sample containing oil inclusions with blue fluorescence colors (1.26% Requ). The yellow fluorescent oil was interpreted to be related to the main oil generation and expulsion process, whereas the blue fluorescent oil was mainly controlled by the thermal cracking process of C14+ aromatic hydrocarbons in source rocks, reservoirs, and oil inclusions. This study demonstrates that the fluorescence colors of oil inclusions may be good indicators of thermal maturity in oil systems charged from oil-prone source rocks and, for the first time, makes it possible to quantitatively predict the thermal maturity of oil inclusions based on their fluorescence characteristics. However, biodegradation, water washing, phase separation, and trapping fractionation should be considered before using this correlation because these processes can also influence fluorescence colors.Ping, H., Li, C., Chen, H., George, S.C., Gong, S., 2020. Overpressure release: Fluid inclusion evidence for a new mechanism for the formation of heavy oil. Geology 48, 803-807. oils in sedimentary basins are commonly related to biodegradation and water washing, and thermal degradation of sulfur-rich kerogen at an early hydrocarbon generation stage. However, the potential for overpressure release to form heavy oil has been seldom considered and rarely demonstrated. Paragenetic sequences of diagenetic and oil charge events, pressure-temperature-composition (P-T-x) evolutionary history reconstruction, and molecular geochemical data from a single generation of oil inclusions reveal that heavy shale oil in the PS18–1 well in the Dongpu Depression, Bohai Bay Basin, China, was neither a product of biodegradation nor due to early oil generation during kerogen maturation. Instead, the precipitation and retention of polar compounds of a previously charged, higher-maturity oil from deeper source rocks, induced by intense pressure reduction during basin uplift, represent the most likely mechanism for the formation of the heavy oil. The precipitation of polar compounds during primary and secondary migration due to intense pressure release may be an important mechanism for explaining compositional fractionation effects in the expelled petroleum fluids in source rocks, bitumen, and heavy oil distributions in unconventional shale systems, and deep non-biodegraded heavy oils. This mechanism has wider implications for understanding the hydrocarbon distribution in overpressured basins.Plass, A., Schlosser, C., Sommer, S., Dale, A.W., Achterberg, E.P., Scholz, F., 2020. The control of hydrogen sulfide on benthic iron and cadmium fluxes in the oxygen minimum zone off Peru. Biogeosciences 17, 3685-3704. in oxygen-depleted marine environments can be an important sink or source of bio-essential trace metals in the ocean. However, the key mechanisms controlling the release from or burial of trace metals in sediments are not exactly understood. Here, we investigate the benthic biogeochemical cycling of iron (Fe) and cadmium (Cd) in the oxygen minimum zone off Peru. We combine bottom water and pore water concentrations, as well as benthic fluxes determined from pore water profiles and from in situ benthic chamber incubations, along a depth transect at 12°?S. In agreement with previous studies, both concentration–depth profiles and in situ benthic fluxes indicate a release of Fe from sediments to the bottom water. Diffusive Fe fluxes and Fe fluxes from benthic chamber incubations (?0.3 to ?17.5?mmol?m?2?yr?1) are broadly consistent at stations within the oxygen minimum zone, where the flux magnitude is highest, indicating that diffusion is the main transport mechanism of dissolved Fe across the sediment–water interface. The occurrence of mats of sulfur-oxidizing bacteria on the seafloor represents an important control on the spatial distribution of Fe fluxes by regulating hydrogen sulfide (H2S) concentrations and, potentially, Fe sulfide precipitation within the surface sediment. Rapid removal of dissolved Fe after its release to anoxic bottom waters hints at oxidative removal by nitrite and interactions with particles in the near-bottom water column. Benthic flux estimates of Cd suggest a flux into the sediment within the oxygen minimum zone. Fluxes from benthic chamber incubations (up to 22.6??mol?m?2?yr?1) exceed diffusive fluxes (<1??mol?m?2?yr?1) by a factor of more than 25, indicating that downward diffusion of Cd across the sediment–water interface is of subordinate importance for Cd removal from benthic chambers. As Cd removal in benthic chambers covaries with H2S concentrations in the pore water of surface sediments, we argue that Cd removal is mediated by precipitation of cadmium sulfide (CdS) within the chamber water or directly at the sediment–water interface. A mass balance approach, taking the contributions of diffusive and chamber fluxes as well as Cd delivery with organic material into account, suggests that CdS precipitation in the near-bottom water could make an important contribution to the overall Cd mass accumulation in the sediment solid phase. According to our results, the solubility of trace metal sulfide minerals (Cd???Fe) is a key factor controlling trace metal removal and, consequently, the magnitude and the temporal and spatial heterogeneity of sedimentary fluxes. We argue that, depending on their sulfide solubility, sedimentary source or sink fluxes of trace metals will change differentially as a result of declining oxygen concentrations and the associated expansion of sulfidic surface sediments. Such a trend could cause a change in the trace metal stoichiometry of upwelling water masses with potential consequences for marine ecosystems in the surface ocean.Plyushchenko, I., Shakhmatov, D., Bolotnik, T., Baygildiev, T., Nesterenko, P.N., Rodin, I., 2020. An approach for feature selection with data modelling in LC-MS metabolomics. Analytical Methods 12, 3582-3591. data processing workflow for LC-MS based metabolomics study is suggested with signal drift correction, univariate analysis, supervised learning, feature selection and unsupervised modelling. The proposed approach requires only an annotation-free peak table and produces an extremely reduced set of the most relevant features together with validation via Receiver Operating Characteristic analysis for selected predictors, cross-validation and unsupervised projection. The presented study was initially optimised by its own experimental set and then was successfully tested by using 36 datasets from 21 publicly available metabolomics projects. The suggested workflow can be used for classification purposes in high dimensional metabolomics studies and as a first step in exploratory analysis, data projection, biomarker selection, data integration and fusion.Polissar, P.J., Rose, C., Uno, K.T., Phelps, S.R., deMenocal, P., 2020. Reply to: Multiple drivers of Miocene C4 ecosystem expansions. Nature Geoscience 13, 465-467. Paper: Polissar, P.J., Rose, C., Uno, K.T. et al. Synchronous rise of African C4 ecosystems 10 million years ago in the absence of aridification. Nat. Geosci. 12, 657–660 (2019). Comment: Schefu?, E., Dupont, L.M., 2020. Multiple drivers of Miocene C4 ecosystem expansions. Nature Geoscience 13, 463-464.We identify the emergence and expansion of C4 ecosystems in four different sediment cores from two oceans, including regions offshore Northwest, West and East Africa. The patterns of δ13C change are common to all sites, synchronous at ~10?Myr ago (Ma), replicated in timing by the C4 dietary signature of East African mammals and consistent with what is known about leaf-wax n-alkanes in modern African vegetation. Any alternative interpretation of the data must address these observations.In conclusion, we regard the consistent data from four different sites in two distinct geographic regions as evidence for the early establishment of C4 ecosystems in Northwest and East Africa in the absence of aridification. The parsimonious explanation is that declining CO2 levels drove the emergence of these ecosystems. The divergence of proxy CO2 estimates through this time interval is a central problem in palaeoclimate studies that many research groups are working on from different angles. A decline in CO2 preceding and accompanying the emergence of C4 ecosystems is consistent with recent CO2 estimates for this time period21,22. Because we rule out any substantial temperature or hydrologic change, our data support the argument of Herbert et al.23 and the hypothesis of Cerling et al.24 and Ehleringer et al.25: the late Miocene temperature decline and early African C4 ecosystem expansion were driven by declining CO2.Poniecka, E.A., Bagshaw, E.A., Sass, H., Segar, A., Webster, G., Williamson, C., Anesio, A.M., Tranter, M., 2020. Physiological capabilities of cryoconite hole microorganisms. Frontiers in Microbiology 11, 1783. doi: 10.3389/fmicb.2020.01783. holes are miniature freshwater aquatic ecosystems that harbor a relatively diverse microbial community. This microbial community can withstand the extreme conditions of the supraglacial environment, including fluctuating temperatures, extreme and varying geochemical conditions and limited nutrients. We analyzed the physiological capabilities of microbial isolates from cryoconite holes from Antarctica, Greenland, and Svalbard in selected environmental conditions: extreme pH, salinity, freeze-thaw and limited carbon sources, to identify their physiological limits. The results suggest that heterotrophic microorganisms in cryoconite holes are well adapted to fast-changing environmental conditions, by surviving multiple freeze-thaw cycles, a wide range of salinity and pH conditions and scavenging a variety of organic substrates. Under oxic and anoxic conditions, the communities grew well in temperatures up to 30°C, although in anoxic conditions the community was more successful at colder temperatures (0.2°C). The most abundant cultivable microorganisms were facultative anaerobic bacteria and yeasts. They grew in salinities up to 10% and in pH ranging from 4 to 10.5 (Antarctica), 2.5 to 10 (Svalbard), and 3 to 10 (Greenland). Their growth was sustained on at least 58 single carbon sources and there was no decrease in viability for some isolates after up to 100 consecutive freeze-thaw cycles. The elevated viability of the anaerobic community in the lowest temperatures indicates they might be key players in winter conditions or in early melt seasons, when the oxygen is potentially depleted due to limited flow of meltwater. Consequently, facultative anaerobic heterotrophs are likely important players in the reactivation of the community after the polar night. This detailed physiological investigation shows that despite inhabiting a freshwater environment, cryoconite microorganisms are able to withstand conditions not typically encountered in freshwater environments (namely high salinities or extreme pH), making them physiologically more similar to arid soil communities. The results also point to a possible resilience of the most abundant microorganisms of cryoconite holes in the face of rapid change regardless of the location.Prater, I., Zubrzycki, S., Buegger, F., Zoor-Füllgraff, L.C., Angst, G., Dannenmann, M., Mueller, C.W., 2020. From fibrous plant residues to mineral-associated organic carbon – the fate of organic matter in Arctic permafrost soils. Biogeosciences 17, 3367-3383. soils of the Arctic account for 70?% or 727?Pg of the soil organic carbon (C) stored in the northern circumpolar permafrost region and therefore play a major role in the global C cycle. Most studies on the budgeting of C storage and the quality of soil organic matter (OM; SOM) in the northern circumpolar region focus on bulk soils. Thus, although there is a plethora of assumptions regarding differences in terms of C turnover or stability, little knowledge is available on the mechanisms stabilizing organic C in Arctic soils besides impaired decomposition due to low temperatures. To gain such knowledge, we investigated soils from Samoylov Island in the Lena River delta with respect to the composition and distribution of organic C among differently stabilized SOM fractions. The soils were fractionated according to density and particle size to obtain differently stabilized SOM fractions differing in chemical composition and thus bioavailability. To better understand the chemical alterations from plant-derived organic particles in these soils rich in fibrous plant residues to mineral-associated SOM, we analyzed the elemental, isotopic and chemical composition of particulate OM (POM) and clay-sized mineral-associated OM (MAOM). We demonstrate that the SOM fractions that contribute with about 17?kg?C?m?3 for more than 60?% of the C stock are highly bioavailable and that most of this labile C can be assumed to be prone to mineralization under warming conditions. Thus, the amount of relatively stable, small occluded POM and clay-sized MAOM that currently accounts with about 10?kg?C?m?3 for about 40?% of the C stock will most probably be crucial for the quantity of C protected from mineralization in these Arctic soils in a warmer future. Using δ15N as a proxy for nitrogen (N) balances indicated an important role of N inputs by biological N fixation, while gaseous N losses appeared less important. However, this could change, as with about 0.4?kg?N?m?3 one third of the N is present in bioavailable SOM fractions, which could lead to increases in mineral N cycling and associated N losses under global warming. Our results highlight the vulnerability of SOM in Arctic permafrost-affected soils under rising temperatures, potentially leading to unparalleled greenhouse gas emissions from these soils.Profumo, A., Gorroni, A., Guarnieri, S.A., Mellerio, G.G., Cucca, L., Merli, D., 2020. GC-MS qualitative analysis of the volatile, semivolatile and volatilizable fractions of soil evidence for forensic application: A chemical fingerprinting. Talanta 219, 121304. paper proposes a GC-MS analytical method that can be used in forensic investigations, for comparative or provenance studies of soils with the aim to reconnect the evidence to their origin. The volatile, semi-volatile and volatilizable compounds present in soil samples of different sources have been extracted and qualitatively analyzed by GC-MS. The different fractions were extracted by ultrasonic assisted extraction (UAE), and the volatilizable compounds were derivatized by BSTFA-TMCS as silylating agent. Sixty-five soil samples from different locations in northern Italy were collected, analyzed and a GC-MS “fingerprint database” has been created in order to easily access the data for the unknown soil sample provenance obtained with the same procedure and GC apparatus. With this purpose, the origin of blind samples, chosen randomly from those collected, was identified based on a qualitative comparison of the MS chromatographic profiles, which obviates the need for quantitative analyses.Puleo, P.J.K., Axford, Y., McFarlin, J.M., Curry, B.B., Barklage, M., Osburn, M.R., 2020. Late glacial and Holocene paleoenvironments in the midcontinent United States, inferred from Geneva Lake leaf wax, ostracode valve, and bulk sediment chemistry. Quaternary Science Reviews 241, 106384. Lake in Wisconsin, USA, is > 20,000 years old and contains a 30-m thick lacustrine sediment record of mid-continent North American climate and environmental change. Here we describe a sediment record from Geneva Lake spanning the past 14,500 years. From scanning X-ray fluorescence, organic C and N concentrations and isotopes, X-ray diffraction, magnetic susceptibility, and grain size of bulk sediments, we infer changes in sediment sources over time including: abrupt decline in inputs of remobilized loess ～13,400 cal yr BP followed by a gradual transition to organic-rich marl deposition by ～10,400 cal yr BP as the landscape stabilized following a period of permafrost thaw and vegetation development; deposition of a minerogenic unit at ～8,200 cal yr BP that may record enhanced eolian activity during the widespread “8.2 ka event; ” and elevated zinc, lead, and arsenic from human activities following regional industrialization. Within the Holocene marl, we also use isotopic (δ18O and δ13C) and trace metal ratio (Sr/Ca and Mg/Ca) analyses of ostracode valves paired with concentrations and hydrogen isotopic composition (δ2H) of leaf wax n-alkanes to infer climate and hydrological change. Groundwater had a large but declining influence on lake water chemistry from 11,800 to 9,700 cal yr BP, precluding inferences of regional climate from our lacustrine proxies during this period. δ2H values of terrestrial n-C29 alkanes show little variability from 9,700 to present, indicating the average isotopic composition of local precipitation was relatively stable, reflecting stable condensation temperatures and source. In contrast, a gradual trend towards more δ18O- and δ2H-depleted lake water and lower lake water Sr/Ca from 9700 cal yr BP to present suggest decreasing evaporation of lake water and increasing precipitation amounts throughout the Holocene and resulting shorter lake water residence times. Lake water Mg/Ca variations over the past 9,700 years broadly parallel regional pollen-based reconstructions of summer temperatures. Neither Mg/Ca nor terrestrial leaf wax δ2H suggest long-term directional shifts in temperature at this site through the middle to late Holocene, as climate became wetter. It appears that precipitation isotopes did not track local temperatures on millennial timescales in this part of mid-continent North America through the Holocene, and instead may have covaried with changes in Northern Hemisphere latitudinal temperature gradients driven by large Arctic temperature changes.Putman, J.C., Moulian, R., Barrère-Mangote, C., Rodgers, R.P., Bouyssiere, B., Giusti, P., Marshall, A.G., 2020. Probing aggregation tendencies in asphaltenes by gel permeation chromatography. Part 1: Online inductively coupled plasma mass spectrometry and offline Fourier transform ion cyclotron resonance mass spectrometry. Energy & Fuels 34, 8308-8315. study probes the nanoaggregation behavior of asphaltenes by gel permeation chromatography (GPC). Compounds containing sulfur, vanadium, and nickel were monitored online with elemental detection by inductively coupled plasma mass spectrometry (ICP-MS), and four fractions that vary in nanoaggregation state were analyzed by positive atmospheric pressure photoionization 9.4 T Fourier transform ion cyclotron resonance mass spectrometry ((+)APPI FT-ICR MS). We also highlight some of the challenges associated with the analysis of asphaltene fractions by direct infusion. Nanoaggregate size and monomer ion yield were inversely correlated. The extremely low ionization efficiency for the largest aggregate GPC fractions collected from the asphaltenes limited their characterization to only a few of the most abundant heteroatom classes. However, for all of the characterizable heteroatom classes, aggregation closely correlated with increased relative abundance of larger, more aliphatic compounds. These observations agree with results from the parent whole crude oil, suggesting that the interactions among the more alkylated compounds in asphaltenes may be a major contributor to asphaltene nanoaggregation.Qi, W., Wang, Y., Cao, Y., Cao, Y., Guan, Q., Sun, T., Zhang, L., Guo, Y., 2020. Simultaneous analysis of fatty alcohols, fatty aldehydes, and sterols in thyroid tissues by electrospray ionization-ion mobility-mass spectrometry based on charge derivatization. Analytical Chemistry 92, 8644-8648. this work, we developed a rapid and high-sensitivity method for simultaneous analyses of fatty alcohols, fatty aldehydes, and sterols by combining the optimized derivatization reaction with electrospray ionization-ion mobility-mass spectrometry (ESI-IM-MS). Pyridine and thionyl chloride were used as derivatization reagents as they were easily removed after the derivatization reaction and could generate permanently charged tags on different functional groups including hydroxyls and aldehydes. Through this one-step derivatization reaction, the sensitivity of detection for fatty alcohols, fatty aldehydes, and sterols was significantly increased. Moreover, the introduction of ion mobility spectrometry (IMS), offering an additional resolution power, ensured more sensitive and accurate detection of derivative products without increasing analytical time. Being connected with high-performance liquid chromatography, more than 15 kinds of compounds were analyzed within 4 min. Relative quantification using peak intensity ratios between d0-/d5-labeled ions were subsequently applied for analyzing these 15 kinds of compounds in human thyroid carcinoma and para-carcinoma tissues. The results showed significant differences in content of some analytes between these two kinds of tissues (p < 0.05). The correlations between most of the analytes in thyroid carcinoma tissues are better than the correlations in para-carcinoma tissues.Qiao, J., Liu, L., Shang, X., 2020. Deposition conditions of the Jurassic lacustrine source rocks in the East Fukang Sag, Junggar Basin, NW China: Evidence from major and trace elements. Geological Journal 55, 4936-4953. Fukang Sag hosts prolific Jurassic lacustrine source rocks, which include the Badaowan (J1b), Sangonghe (J1s), and Xishanyao (J2x) formations in the Junggar Basin. Depositional conditions were reconstructed based on various major and trace element proxies for the East Fukang Sag during the Jurassic. The palaeowater depth in the sag was shallow and did not display a great change during the deposition of the J1b, J1s, and J2x formations, as indicated by lithological composition and the widespread ripple cross‐beddings. The oxic to dysoxic and fresh‐water conditions were postulated to prevail in the sag during the deposition of these source rocks, as revealed by concentrations of salinity‐ and redox‐sensitive trace elements [i.e., V/Cr, Ni/Co, (Cu+Mo)/Zn, Sr/Ba ratios, and Sr, Mn, Ga contents] derived from the source rocks. The seasonal salinity stratification superposed on preexisting thermal stratification led to the appearance of the chemocline in the J1b Formation. The palaeoclimate regime was humid and warm during the depositions of the J1b and the upper J1s formations, and warmer and drier during the deposition of the lower J1s Formation, but the palaeoclimate gradually became semi‐arid and semi‐cold during the deposition of the upper J2x Formation, as implied by various proxies (i.e., Sr/Cu ratio, C‐value, and CIA value). Despite the fact that the oxic to dysoxic conditions were not conducive for organic matter (OM) preservation, the significantly moderate‐high palaeoproductivity (suggested by, i.e., Ba content and Ba/Al ratio), which was promoted by a suitable supply of nutrient from terrestrial inputs in the shallow water was the controlling factorfor the OM accumulation on the margin of the sag, but the low OM concentration was controlled by the palaeoredox conditions in the central area, which was far from the OM input source [suggested by the relationship between total organic carbon content and stable carbon isotope composition of OM (δ13Corg)]. The analyses based on Rock‐Eval pyrolysis, maceral composition, C/N ratio of isolated kerogen, and δ13Corg value showing the OM was derived from terrestrial higher plants with C3 plants (type III kerogen) are consistent with the palaeoenvironmental analysis.Qin, X.-w., Lu, J.-a., Lu, H.-l., Qiu, H.-j., Liang, J.-q., Kang, D.-j., Zhan, L.-s., Lu, H.-f., Kuang, Z.-g., 2020. Coexistence of natural gas hydrate, free gas and water in the gas hydrate system in the Shenhu Area, South China Sea. China Geology 3, 210-220. Shenhu Area is located in the Baiyun Sag of Pearl River Mouth Basin, which is on the northern continental slope of the South China Sea. Gas hydrates in this area have been intensively investigated, achieving a wide coverage of the three-dimensional seismic survey, a large number of boreholes, and detailed data of the seismic survey, logging, and core analysis. In the beginning of 2020, China has successfully conducted the second offshore production test of gas hydrates in this area. In this paper, studies were made on the structure of the hydrate system for the production test, based on detailed logging data and core analysis of this area. As to the results of nuclear magnetic resonance (NMR) logging and sonic logging of Well GMGS6-SH02 drilled during the GMGS6 Expedition, the hydrate system on which the production well located can be divided into three layers: (1) 207.8–253.4 mbsf, 45.6 m thick, gas hydrate layer, with gas hydrate saturation of 0–54.5% (31% av.); (2) 253.4–278 mbsf, 24.6 m thick, mixing layer consisting of gas hydrates, free gas, and water, with gas hydrate saturation of 0–22% (10% av.) and free gas saturation of 0–32% (13% av.); (3) 278–297 mbsf, 19 m thick, with free gas saturation of less than 7%. Moreover, the pore water freshening identified in the sediment cores, taken from the depth below the theoretically calculated base of methane hydrate stability zone, indicates the occurrence of gas hydrate. All these data reveal that gas hydrates, free gas, and water coexist in the mixing layer from different aspects.Quan, Y., Liu, J., Hao, F., Cai, Z., Xie, Y., 2020. Paleosalinity assessment and its influence on source rock deposition in the western Pearl River Mouth Basin, South China Sea. GSA Bulletin 132, 1741-1755. is an important environmental feature but it is difficult to evaluate. In the present study, paleosalinity was assessed during the deposition of three sets of source rocks in the western Pearl River Mouth Basin, South China Sea, utilizing four different kinds of methods, i.e., saturated hydrocarbon biomarkers, strontium abundance, non-pollen microalgae assemblies, and carbon-sulfur relationships.Results show that the second member of the Eocene Wenchang Formation (E2w2) was deposited in a freshwater environment and the Oligocene Zhuhai Formation (E3z) was deposited in a shallow marine environment. The Oligocene Enping Formation (E3e), which was believed to be deposited in a freshwater environment, was actually deposited in a brackish water environment. Mechanisms of salinity increase during the non-marine E3e deposition were mainly deep hydrothermal fluid input through the south boundary fault and episodic marine transgressions, not evaporation. The effect of salinity on organic matter content and type was investigated. Results show that salinity has no significant influence on total organic carbon (TOC) and hydrogen index (HI) of the E2w2, which was caused by the balance between freshwater algae and euryhaline algae. TOC and HI decrease with increasing salinity for samples from the E3z, which is contrary to the conventional hypothesis that marine transgressions promote source rock deposition. The decrease of TOC with carbon/sulfur ratios for samples from the E3e actually reflect the influence of thermal maturity but thermal maturity only plays the second role in HI. The effect of salinity on HI during the E3e deposition can be divided into two stages. During the first stage, the increase of salinity was mainly caused by deep hydrothermal fluid input without an oxygen level increase. HI values, therefore, remained relatively stable. During the secondary stage, the increase of salinity was mainly caused by marine transgressions which increased the oxygen level and as a consequence, HI decreased sharply with increasing salinity.This study provides a long-term salinity evolution of the western Pearl River Mouth Basin and suggests that salinity is an important factor controlling source rock deposition. In addition, this study presents an example that goes against conventional wisdom that marine transgressions promote source rock deposition in a shallow marine environment. This study also suggested that marine transgressions had already begun at the end of the early Oligocene.Rabbel, O., Mair, K., Galland, O., Grühser, C., Meier, T., 2020. Numerical modeling of fracture network evolution in organic-rich shale with rapid internal fluid generation. Journal of Geophysical Research: Solid Earth 125, e2020JB019445. low‐permeability and organic‐rich rocks such as shale experience sufficient heating, chemical reactions including shale dehydration and maturation of organic matter lead to internal fluid generation. This may cause substantial pore fluid overpressure and fracturing. In the vicinity of igneous intrusions emplaced in organic‐rich shales, temperatures of several hundred degrees accelerate these processes and lead to intense fracturing. The resulting fracture network provides hydraulic pathways, which allow fluid expulsion and affect hydrothermal fluid flow patterns. However, the evolution of these complex fracture networks and controls on geometry and connectivity are poorly understood. Here, we perform a numerical modeling study based on the extended finite element method to investigate coupled hydromechanical fracture network evolution due to fast internal fluid generation. We quantify the evolution of different initial fracture networks under varying external stresses by analyzing parameters including fracture length, opening, connectivity, and propagation angles. The results indicate a three‐phase process including (1) individual growth, (2) interaction, and (3) expulsion phase. Magnitude of external stress anisotropy and degree of fracture alignment with the largest principal stress correlate with increased fracture opening. We additionally find that although the external stress field controls the overall fracture orientation distribution, local stress interactions may cause significant deviations of fracture paths and control the coalescence characteristics of fractures. Establishing high connectivity in cases with horizontally aligned initial fractures requires stress anisotropy with σ V > σ H , while the initial orientation distribution is critical for connectivity if stresses are nearly isotropic.Raitzsch, M., Bijma, J., Bickert, T., Schulz, M., Holbourn, A., Ku?era, M., 2020. Eccentricity-paced atmospheric carbon-dioxide variations across the middle Miocene climate transition. Climate of the Past Discussions 2020, 1-22. middle Miocene climate transition ~?14?Ma marks a fundamental step towards the current “icehouse” climate, with a ~?1?‰ δ18O increase and a ~?1?‰ transient δ13C rise in the deep ocean, indicating rapid expansion of the East Antarctic Ice Sheet associated with a change in the operation of the global carbon cycle. The variation of atmospheric CO2 across the carbon-cycle perturbation has been intensely debated as proxy records of pCO2 for this time interval are sparse and partly contradictory. Using boron isotopes (δ11B) in planktonic foraminifers from drill site ODP 1092 in the South Atlantic, we show that long-term pCO2 variations between ~?14.3 and 13.2?Ma were paced by 400?k.y. eccentricity cycles, with decreasing pCO2 at high eccentricity and vice versa. Our data support results from a carbon-cycle model study, according to which increased monsoon intensity at high eccentricity enhanced weathering and river fluxes in the tropics, resulting in increasing carbonate and organic carbon burial and hence decreasing atmospheric CO2. In this scenario, a combination of the eccentricity-driven climatic cycle and enhanced meridional deep-ocean circulation during Antarctic ice-sheet expansion may have both contributed to the pCO2 rise following Antarctic glaciation, acting as a negative feedback on the progressing glaciation and helping to stabilize the climate system on its way to the late Cenozoic “icehouse” world.Randolph, C.E., Marshall, D.L., Blanksby, S.J., McLuckey, S.A., 2020. Charge-switch derivatization of fatty acid esters of hydroxy fatty acids via gas-phase ion/ion reactions. Analytica Chimica Acta 1129, 31-39. fatty acid esters of hydroxy fatty acids (FAHFAs) are a recently discovered class of endogenous bioactive lipids with anti-diabetic and anti-inflammatory effects. Identification of FAHFAs is challenging due to both the relatively low abundance of these metabolites in most biological samples and the significant structural diversity arising from the co-occurrence of numerous regioisomers. Ultimately, development of sensitive analytical techniques that enable rapid and unambiguous identification of FAHFAs is integral to understanding their diverse physiological functions in health and disease. While a battery of mass spectrometry (MS) based methods for complex lipid analysis has been developed, FAHFA identification presents specific challenges to conventional approaches. Notably, while the MS2 product ion spectra of [FAHFA – H]? anions afford the assignment of fatty acid (FA) and hydroxy fatty acid (HFA) constituents, FAHFA regioisomers are usually indistinguishable by this approach. Here, we report the development of a novel MS-based technique employing charge inversion ion/ion reactions with tris-phenanthroline magnesium complex dications, Mg(Phen)32+, to selectively and efficiently derivatize [FAHFA – H]? anions in the gas phase, yielding fixed-charge cations. Subsequent activation of [FAHFA – H + MgPhen2]+ cations yield product ions that facilitate the assignment of FA and HFA constituents, pinpoints unsaturation sites within the FA moiety, and elucidates ester linkage regiochemistry. Collectively, the presented approach represents a rapid, entirely gas-phase method for near-complete FAHFA structural elucidation and confident isomer discrimination without the requirement for authentic FAHFA standards.Ratnakar, R.R., Venkatraman, A., Kalra, A., Dindoruk, B., 2020. On the prediction of gas solubility in brine solutions with single or mixed salts: Applications to gas injection and CO2 capture/sequestration. Journal of Natural Gas Science and Engineering 81, 103450. of gas solubility in a brine solution is essential for many chemical/petroleum industrial applications including EOR with gas injection, geological storage of CO2 in deep saline aquifers, mitigation of corrosion related issues for sour gas fields and many more. Since the type of salt can significantly alter the gas-solubility in formation brine, we develop a robust methodology to predict the impact of different types of salts on solubility of a gas in a brine solution. The method uses ionic-strength-based mixing rule and extends the well-known Setschenow relation to capture the impact of mixture of salts containing mono- or multi-valent ions. The model is validated with new experimental solubility measurements of a novel gas (dimethyl either) in brine with various salt mixtures. In addition, the unique/characteristic constants used in model for each component (gas, anions and cations) are correlated with their thermodynamic properties and can easily be obtained for novel gas-salt systems.Razaz, M., Di Iorio, D., Wang, B., Daneshgar Asl, S., Thurnherr, A.M., 2020. Variability of a natural hydrocarbon seep and its connection to the ocean surface. Scientific Reports 10, 12654. hydrocarbon seeps are ubiquitous along continental margins. Despite their significance, we lack a basic understanding of the long-term temporal variability of seep dynamics, including bubble size, rise velocity, composition, and upwelling and entrainment processes. The shortcoming makes it difficult to constrain the global estimates of oil and gas entering the marine environment. Here we report on a multi-method approach based on optical, acoustic, satellite remote sensing, and simulations, to connect the characteristics of a hydrocarbon seep in the Gulf of Mexico to its footprint on the sea surface. Using an in-situ camera, bubble dynamics at the source were measured every 6 h over 153 days and the integrated total hydrocarbon release volume was estimated as 53 m3. The vertical velocity was acoustically measured at 20 m above bed (mab) and found to be approximately 40% less than the dispersed-phase at the source, indicating that the measured values are reflecting the plume continuous-phase flow. Numerical simulations predict that the oily bubbles with diameters larger than 8 mm reach the surface with a small footprint, i.e. forming an oil slick origin, deflection of which with wind and surface current leads to the formation of an oil slick on the surface. Nineteen SAR images are used to estimate the oil seepage rate from GC600 for 2017 giving an average discharge of 14.4 cm3/s.Reimink, J.R., Mundl-Petermeier, A., Carlson, R.W., Shirey, S.B., Walker, R.J., Pearson, D.G., 2020. Tungsten isotope composition of Archean crustal reservoirs and implications for terrestrial μ182W evolution. Geochemistry, Geophysics, Geosystems 21, e2020GC009155. evolution of Earth's major geochemical reservoirs over ~4.5 × 109 years remains a matter of intense study. Geochemical tools in the form of short‐lived radionuclide isotope ratios (142Nd/144Nd and 182W/184W) have expanded our understanding of the geochemical variability in both the modern and ancient Earth. Here, we present 142Nd/144Nd and 182W/184W data from a suite of rocks from the Slave craton that formed over a 1.1 × 109 year time span in the Archean. The rocks have consistently high 182W/184W, yet 142Nd/144Nd that is lower than bulk mantle and increased over time. The declining variability in 142Nd/144Nd with time likely reflects the homogenization of compositional heterogeneities in the silicate Earth that were initially created by differentiation events that occurred prior to 4.2 Ga. The elevated 182W/184W recorded in the Slave samples help refine models for the broader W‐isotope evolution of the silicate Earth. Globally, the Archean mantle that formed continental crust was dominated by 182W/184W elevated by some 10–15 ppm compared to the value for the modern upper mantle. The Slave craton lacks significant volumes of komatiite yet has elevated 182W/184W until 2.9 Ga. This observation, combined with the presence of other komatiite suites that have low 182W/184W, suggests that deep‐seated sources contributed low 182W/184W in the Archean Earth. The regional variability in 182W/184W may be explained by invoking chemical and/or isotopic exchange between a well‐mixed silicate Earth and the core or a portion of the lower mantle whose W‐isotope composition has been influenced by interaction with the core.Reinhard, C.T., Planavsky, N.J., 2020. Biogeochemical controls on the redox evolution of Earth’s oceans and atmosphere. Elements 16, 191-196. redox state of Earth’s atmosphere has undergone a dramatic shift over geologic time from reducing to strongly oxidizing, and this shift has been coupled with changes in ocean redox structure and the size and activity of Earth’s biosphere. Delineating this evolutionary trajectory remains a major problem in Earth system science. Significant insights have emerged through the application of redox-sensitive geochemical systems. Existing and emerging biogeochemical modeling tools are pushing the limits of the quantitative constraints on ocean–atmosphere redox that can be extracted from geochemical tracers. This work is honing our understanding of the central role of Earth’s biosphere in shaping the long-term redox evolution of the ocean–atmosphere system.Reji, L., Francis, C.A., 2020. Metagenome-assembled genomes reveal unique metabolic adaptations of a basal marine Thaumarchaeota lineage. The ISME Journal 14, 2105-2115. constitute an abundant and ubiquitous phylum of Archaea that play critical roles in the global nitrogen and carbon cycles. Most well-characterized members of the phylum are chemolithoautotrophic ammonia-oxidizing archaea (AOA), which comprise up to 5 and 20% of the total single-celled life in soil and marine systems, respectively. Using two high-quality metagenome-assembled genomes (MAGs), here we describe a divergent marine thaumarchaeal clade that is devoid of the ammonia-oxidation machinery and the AOA-specific carbon-fixation pathway. Phylogenomic analyses placed these genomes within the uncultivated and largely understudied marine pSL12-like thaumarchaeal clade. The predominant mode of nutrient acquisition appears to be aerobic heterotrophy, evidenced by the presence of respiratory complexes and various organic carbon degradation pathways. Both genomes encoded several pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenases, as well as a form III RuBisCO. Metabolic reconstructions suggest anaplerotic CO2 assimilation mediated by RuBisCO, which may be linked to the central carbon metabolism. We conclude that these genomes represent a hitherto unrecognized evolutionary link between predominantly anaerobic basal thaumarchaeal lineages and mesophilic marine AOA, with important implications for diversification within the phylum Thaumarchaeota.Riddick, S.N., Mauzerall, D.L., Celia, M.A., Kang, M., Bandilla, K., 2020. Variability observed over time in methane emissions from abandoned oil and gas wells. International Journal of Greenhouse Gas Control 100, 103116. studies have reported methane (CH4) emissions from abandoned oil and gas wells across the United States and the United Kingdom. These emissions can reach hundreds of kg CH4 per year per well and are important to include in greenhouse gas emission inventories and mitigation strategies. Emission estimates are generally based on single, short-term measurements that assume constant emission rates over both short (hours) and longer (months/years) time periods. To investigate this assumption, we measure CH4 emissions from 18 abandoned oil and gas wells in the USA and the UK continuously over 24?h and then make repeat 24?-h measurements at a single site over 12 months. While the lack of historical records for these wells makes it impossible to determine the underlying leakage-pathways, we observed that CH4 emissions at all wells varied over 24?h (range 0.2-81,000?mg CH4 hr?1) with average emissions varying by a factor of 18 and ranging from factors of 1.1–142. We did not find a statistically significant relationship between the magnitude of emissions and variability or that variability is correlated with temperature, relative humidity or atmospheric pressure. The results presented here suggest high CH4 emission events tend to be short-lived, so short-term (< 1?h) sampling is likely to miss them. Our findings present the dynamic nature of CH4 emissions from abandoned oil and gas wells which should be considered when planning measurement methodologies and developing greenhouse gas inventories/mitigation strategies. Incorporation of these temporal dynamics could improve national greenhouse gas emissions inventories.Riding, R., Virgone, A., 2020. Hybrid carbonates: in situ abiotic, microbial and skeletal co-precipitates. Earth-Science Reviews 208, 103300., Bioinduced and Biocontrolled carbonates are process-based sediment categories. They successively reflect increasing levels of biotic control over carbonate precipitation from aqueous solutions, are often closely linked to depositional environment, and change with time. Hybrid Carbonates are intimate in situ combinations of two or more of these categories. Hybrid Carbonates are widespread and diverse in the marine geological record and reflect large-scale changes in carbonate precipitation through time. They also occur in fluvial and lacustrine carbonates, marine and non-marine reef systems, and methane seep deposits. Plots of Hybrid Carbonate composition in time and space reveal complex ‘backtracking’ and ‘looping’ patterns that reflect changes in environmental conditions and biological processes of carbonate production. Recognition of hybridity emphasizes the importance of distinguishing abiotic and bioinduced precipitates. Until they were diversified by Skeletal Carbonates in the late Proterozoic, Precambrian Hybrid Carbonates were Abiotic-Bioinduced combinations. During the Phanerozoic Hybrid Carbonates were conspicuous during periods of overlap or transition between intervals of Microbial and Skeletal carbonate abundance. Microbial-Skeletal Dual Hybrids are common during the Cambrian-mid Ordovician, Late Devonian-Mississippian, and Late Jurassic-Early Cretaceous. Abiotic-Microbial-Skeletal Triple Hybrids were common from Late Pennsylvanian to mid-Triassic. Shallow marine Hybrid Carbonates declined in abundance after the mid-Cretaceous, although Late Cenozoic reefs contain some striking examples of Microbial-Skeletal Hybrids. Recognition of Hybrid Carbonates draws attention to fundamental processes underlying carbonate sedimentation, and their patterns and drivers of change in time and space.Riehl, T., W?lfl, A.-C., Augustin, N., Devey, C.W., Brandt, A., 2020. Discovery of widely available abyssal rock patches reveals overlooked habitat type and prompts rethinking deep-sea biodiversity. Proceedings of the National Academy of Sciences 117, 15450-15459.: Ground-truthed analyses of multibeam sonar data along a fracture zone of the northern Mid-Atlantic Ridge reveal an abyssal seafloor much rockier than previously assumed. Our data show rock exposures occurring at all crustal ages from 0–100 Ma along the Vema Fracture Zone and that approximately 260,000 km2 of rock habitats can be expected to occur along Atlantic fracture zones alone. This higher than expected geodiversity implies that future sampling campaigns should be considerably more sophisticated than at present to capture the full deep-sea habitat heterogeneity. We provide a baseline to unravel the processes responsible for the evolution and persistence of biodiversity on the deep seafloor as well as to determine the significant scales of these processes in the benthoscape.Abstract: Habitat heterogeneity and species diversity are often linked. On the deep seafloor, sediment variability and hard-substrate availability influence geographic patterns of species richness and turnover. The assumption of a generally homogeneous, sedimented abyssal seafloor is at odds with the fact that the faunal diversity in some abyssal regions exceeds that of shallow-water environments. Here we show, using a ground-truthed analysis of multibeam sonar data, that the deep seafloor may be much rockier than previously assumed. A combination of bathymetry data, ruggedness, and backscatter from a trans-Atlantic corridor along the Vema Fracture Zone, covering crustal ages from 0 to 100 Ma, show rock exposures occurring at all crustal ages. Extrapolating to the whole Atlantic, over 260,000 km2 of rock habitats potentially occur along Atlantic fracture zones alone, significantly increasing our knowledge about abyssal habitat heterogeneity. This implies that sampling campaigns need to be considerably more sophisticated than at present to capture the full deep-sea habitat heterogeneity and biodiversity.Rinaldi, M., Paglione, M., Decesari, S., Harrison, R.M., Beddows, D.C.S., Ovadnevaite, J., Ceburnis, D., O’Dowd, C.D., Simó, R., Dall’Osto, M., 2020. Contribution of water-soluble organic matter from multiple marine geographic eco-regions to aerosols around Antarctica. Environmental Science & Technology 54, 7807-7817. present shipborne measurements of size-resolved concentrations of aerosol components across ocean waters next to the Antarctic Peninsula, South Orkney Islands, and South Georgia Island, evidencing aerosol features associated with distinct eco-regions. Nonmethanesulfonic acid Water-Soluble Organic Matter (WSOM) represented 6–8% and 11–22% of the aerosol PM1 mass originated in open ocean (OO) and sea ice (SI) regions, respectively. Other major components included sea salt (86–88% OO, 24–27% SI), non sea salt sulfate (3–4% OO, 35–40% SI), and MSA (1–2% OO, 11–12% SI). The chemical composition of WSOM encompasses secondary organic components with diverse behaviors: while alkylamine concentrations were higher in SI air masses, oxalic acid showed higher concentrations in the open ocean air. Our online single-particle mass spectrometry data exclude a widespread source from sea bird colonies, while the secondary production of oxalic acid and sulfur-containing organic species via cloud processing is suggested. We claim that the potential impact of the sympagic planktonic ecosystem on aerosol composition has been overlooked in past studies, and multiple eco-regions act as distinct aerosol sources around Antarctica.Roerdink, D., 2020. Redrawing the early sulfur cycle. Nature Geoscience 13, 526-527. Archaean atmosphere may have been well oxygenated, according to a reconsideration of sulfur cycling at that time. This challenges the view that sedimentary sulfur records oxygen-poor conditions during Earth’s first two billion years.The rise of atmospheric oxygen represents one of the most important geochemical events in Earth’s history. To date, most evidence points to an atmosphere with little free oxygen during the Archaean eon some 4.0 to 2.5 billion years ago (Ga), followed by a stepwise increase in atmospheric oxygen starting at the Great Oxidation Event around 2.4 Ga1. The rise of free oxygen in the atmosphere enabled the evolution of multicellular life, changed the supply of nutrients by oxidative weathering and solubility of bio-essential metals in seawater, and may have triggered the first global glaciation1,2. Reconstructing the timing of this major change relies on proxies sensitive to the presence of oxygen in the surface environment3. However, some researchers remain sceptical of the interpretation of a stepwise progression towards more oxic conditions from the geologic record4,5. Writing in Nature Geoscience, Ohmoto6 presents an alternative model of the Archaean sulfur cycle that instead requires an oxygenated atmosphere closer to the one we have today.Trends in the characteristics of sulfur preserved in the sedimentary rock record have been key to unravelling Earth’s surface conditions through geologic time. Sulfur can be preserved in both its oxidized (sulfate) and reduced (sulfide) forms, and redox reactions produce diagnostic and predictable differences in its stable isotope ratios. Two decades ago, anomalous sulfur isotope signatures that deviated from these predictions were found in sedimentary rocks older than 2.4 billion years old7. This so-called mass-independent isotope fractionation has been linked to photolysis, the photochemical reaction between volcanic sulfur dioxide and ultraviolet light, and is thought to require very low atmospheric oxygen levels to be generated and preserved in the rock record8. The assumed low-oxygen atmosphere in turn implies an Archaean sulfur cycle with low sulfate concentrations in seawater, as the supply of sulfate by oxidative weathering on land is negligible under low atmospheric oxygen levels. The observed disappearance of mass-independent sulfur isotope signatures in sedimentary rocks younger than 2.4 Ga has been viewed by many as smoking gun evidence for the rise of atmospheric oxygen at this time1.Ohmoto challenges this popular paradigm. Based on a combination of chemical modelling and sulfur isotope data compiled from volcanic and hydrothermal minerals, Ohmoto infers that subaerial degassing of oxidized magmas in subduction zones (Fig. 1) must have been the main source of volcanic sulfur dioxide to the Archaean atmosphere. According to their calculations, the generation of these oxidized arc magmas by recycling and dehydration of hydrothermally altered oceanic crust would have required seawater sulfate levels of about 1 mM SO42–. Remarkably, this concentration is more than 400 times higher than the current estimate for sulfate in Archaean seawater9. The oxidative weathering needed to support this influx of sulfate also requires an oxygenated atmosphere to have been present well before the Great Oxidation Event, which clearly conflicts with previous interpretations regarding the origin of anomalous sulfur isotope signatures in Archaean sedimentary rocks. Instead, Ohmoto concludes that mass-independent fractionation occurred during high-temperature reactions between sulfate and organic matter in submarine hydrothermal systems or during large, explosive volcanic eruptions when sulfur dioxide reached the low-oxygen stratosphere and underwent photolysis. Both processes could have occurred in an Archaean atmosphere with an oxygen concentration about 50% of that today.Undoubtedly, the work by Ohmoto will raise some eyebrows in the early Earth community. It presents a holistic approach that integrates mantle and surface processes into a sulfur cycle model that requires free oxygen as early as 3.8 Ga, and addresses the origin of volcanic sulfur dioxide in the Archaean eon. However, the proposed sulfur cycle does not explain away the isotopic evidence for low sulfate concentrations in the early oceans9, the lack of ubiquitous marine sulfate deposits in the rock record before 2.4 Ga10, and the wide range of geochemical proxies that suggest a major change in surface redox conditions at the end of the Archaean3. Indirectly, the work emphasizes the persistent mismatch between anomalous sulfur isotope ratios observed in the Archaean rock record and results obtained from laboratory experiments and models. For instance, proposed photochemical11 and hydrothermal pathways12 for mass-independent fractionation have not been able to fully reproduce the signs and magnitudes of sulfur isotope signatures measured in Archaean sulfide and sulfate minerals. This leaves the mechanistic origin of mass-independent sulfur isotope fractionation open to debate.Ohmoto has demonstrated a mechanism for the generation of volcanic sulfur dioxide in the Archaean that requires sulfate-rich oceans under an oxygenated atmosphere. Continuing investigation of mass-independent isotope fractionation will help to inform the debate as to whether an oxygen-rich atmosphere is consistent with sulfur isotope signatures measured in Archaean sedimentary rocks, or if the broadly accepted stepwise oxygenation of the atmosphere holds up after all.References1. Lyons, T. W., Reinhard, C. T. & Planavsky, N. J. Nature 506, 307–315 (2014).2. Anbar, A. D. Science 322, 1481–1483 (2008).3. Catling, D. C. & Zahnle, K. J. Sci. Adv. 6, eaax1420 (2020).4. Hoashi, M. et al. Nat. Geosci. 2, 301–306 (2009).5. Ohmoto, H., Watanabe, Y., Ikemi, H., Poulson, S. R. & Taylor, B. E. Nature 442, 908–911 (2006).6. Ohmoto, H. Nat. Geosci. (2020).7. Farquhar, J., Bao, H. & Thiemens, M. Science 289, 756–759 (2000).8. Pavlov, A. A. & Kasting, J. F. Astrobiology 2, 27–41 (2002).9. Crowe, S. A. et al. Science 346, 735–739 (2014).10. Huston, D. L. & Logan, G. A. Earth Planet. Sci. Lett. 220, 41–55 (2004).11. Ono, S. Annu. Rev. Earth Planet. Sci. 45, 301–329 (2017).12. Watanabe, Y., Farquhar, J. & Ohmoto, H. Science 324, 370–373 (2009).R?mer, M., Sahling, H., dos Santos Ferreira, C., Bohrmann, G., 2020. Methane gas emissions of the Black Sea—mapping from the Crimean continental margin to the Kerch Peninsula slope. Geo-Marine Letters 40, 467-480. study focuses on gas bubble emissions across ~?1800?km2 of the southeastern continental slope of the Crimean Peninsula in the Eastern Black Sea basin. In total, about 3500 gas emissions were mapped as so-called flares in single- and multibeam echosounder imaginary. Flares generally emanate from the seafloor, with a few exceptions, where water depths are less than 700?m, which represents the upper limit of the gas hydrate stability zone in this region. Methane in shallow sediments below 700?m is transferred to methane hydrate, and the migration of free gas into the water column is therefore inhibited in most cases. This study illustrates further that flare occurrence is linked to morpho-structural margin characteristics. Two morphologically different margin segments are distinguished, and flare distributions were found to relate to differing morphological structures along these segments. In the western province, where the upper continental margin is steep and incised by gullies, flares occur mainly along downslope-oriented ridge crests. In the eastern province, representing a part of the Don-Kuban paleo-fan, the slope is influenced by extensive mass wasting. Gas emissions in this area were mainly detected aligned along scarps of submarine landslides and related to sediment failures. Almost all flares disappear in the acoustic records of the water column below a water depth of ~?100 m suggesting that the gas bubbles dissolve within the water body of the Black Sea and contribute to its methane inventory and the anoxic water column.Rooker, J.R., Wells, R.J.D., Addis, P., Arrizabalaga, H., Baptista, M., Bearzi, G., Dance, M.A., Fraile, I., Lacoue-Labarthe, T., Lee, J.M., Megalofonou, P., Rosa, R., Sobrino, I., Sykes, A.V., Villanueva, R., 2020. Natural geochemical markers reveal environmental history and population connectivity of common cuttlefish in the Atlantic Ocean and Mediterranean Sea. Journal of The Royal Society Interface 17, 20200309. markers (δ13C and δ18O stable isotopes) in the cuttlebones of the European common cuttlefish (Sepia officinalis) were determined for individuals collected across a substantial portion of their range in the Northeast Atlantic Ocean (NEAO) and Mediterranean Sea. Cuttlebone δ13C and δ18O were quantified for core and edge material to characterize geochemical signatures associated with early (juvenile) and recent (sub-adult/adult) life-history periods, respectively. Regional shifts in cuttlebone δ13C and δ18O values were detected across the 12 sites investigated. Individuals collected from sites in the NEAO displayed more enriched δ13C and δ18O values relative to sites in the Mediterranean Sea, with the latter also showing salient differences in both markers among western, central and eastern collection areas. Classification success based on cuttlebone δ13C and δ18O values to four geographical regions (NEAO, western, central and eastern Mediterranean Sea) was relatively high, suggesting that environmental conditions in each region were distinct and produced area-specific geochemical signatures on the cuttlebones of S. officinalis. A modified δ13C and δ18O baseline was developed from sites proximal to the Strait of Gibraltar in both the NEAO and Mediterranean Sea to assess potential mixing through this corridor. Nearly, all (95%) of δ13C and δ18O signatures of S. officinalis collected in the area of the NEAO closest to the Strait of Gibraltar (Gulf of Cadiz) matched the signatures of specimens collected in the western Mediterranean, signifying potential movement and mixing of individuals through this passageway. This study extends the current application of these geochemical markers for assessing the natal origin and population connectivity of this species and potentially other taxa that inhabit this geographical area.Rooney, A.D., Cantine, M.D., Bergmann, K.D., Gómez-Pérez, I., Al Baloushi, B., Boag, T.H., Busch, J.F., Sperling, E.A., Strauss, J.V., 2020. Calibrating the coevolution of Ediacaran life and environment. Proceedings of the National Academy of Sciences 117, 16824-16830.: Our understanding of the interactions between animal evolution, biogeochemical cycling, and global tectonics during the Ediacaran Period (635 to 541 Ma) is severely hampered by lack of a robust temporal framework. The appearance and extinction of the earliest fossil animals are hypothesized to correlate with upheavals in biogeochemical cycles—foremost the Shuram carbon isotope excursion, possibly the largest known disturbance to the global carbon cycle. However, without age constraints on the excursion’s timing and duration, its driving mechanisms, global synchroneity, and role in Ediacaran geobiological evolution cannot be evaluated. We provide radioisotopic ages for the onset and termination of the Shuram, evaluate its global synchroneity, and show that it is divorced from the rise of the earliest preserved animal ecosystems.Abstract: The rise of animals occurred during an interval of Earth history that witnessed dynamic marine redox conditions, potentially rapid plate motions, and uniquely large perturbations to global biogeochemical cycles. The largest of these perturbations, the Shuram carbon isotope excursion, has been invoked as a driving mechanism for Ediacaran environmental change, possibly linked with evolutionary innovation or extinction. However, there are a number of controversies surrounding the Shuram, including its timing, duration, and role in the concomitant biological and biogeochemical upheavals. Here we present radioisotopic dates bracketing the Shuram on two separate paleocontinents; our results are consistent with a global and synchronous event between 574.0 ± 4.7 and 567.3 ± 3.0 Ma. These dates support the interpretation that the Shuram is a primary and synchronous event postdating the Gaskiers glaciation. In addition, our Re-Os ages suggest that the appearance of Ediacaran macrofossils in northwestern Canada is identical, within uncertainty, to similar macrofossils from the Conception Group of Newfoundland, highlighting the coeval appearance of macroscopic metazoans across two paleocontinents. Our temporal framework for the terminal Proterozoic is a critical step for testing hypotheses related to extreme carbon isotope excursions and their role in the evolution of complex life.Rosa, T.R., Folli, G.S., Pacheco, W.L.S., Castro, M.P., Rom?o, W., Filgueiras, P.R., 2020. DropMS: Petroleomics data treatment based in web server for high-resolution mass spectrometry. Journal of the American Society for Mass Spectrometry 31, 1483-1490. have built an online tool with a user-friendly and browser-based interface to facilitate the processing of high resolution and precision oil mass spectrometry data. DropMS does not require software installations. Mass spectra are sent and processed by the server using various algorithms reported in the literature, such as S/N ratio filters, recalibrations, chemical formula assimilations, and data visualization using graphs and diagrams popularly known in mass spectrometry as Van Krevelen and Kendrick diagrams and DBE vs C#. To validate the algorithms used and the processing results, the same mass spectrum of a typical Brazilian oil sample was analyzed by ESI(+)-FT-ICR/MS and processed using Sierra Analytics DropMS and Composer to obtain good agreement between the heteroatomic classes found and the number of compounds assigned. The MS has chemical information spread over the entire spectrum. The PLS multivariate regression has the main objective of decomposing the most important information into latent variables in order to quantify the most evaluated properties. Finally, 12 processed petroleum FT-ICR MS spectra were used for a partial least-squares regression with seven latent variables for R2 = 0.971 and RMSEC of 0.997 for API density property with a reference value range of 21–42.Rosset, T., Binet, S., Antoine, J.-M., Lerigoleur, E., Rigal, F., Gandois, L., 2020. Drivers of seasonal- and event-scale DOC dynamics at the outlet of mountainous peatlands revealed by high-frequency monitoring. Biogeosciences 17, 3705-3722. store ～?20?%–30?% of the global soil organic carbon stock and are an important source of dissolved organic carbon (DOC) for inland waters. Recent improvements for in situ optical monitoring revealed that the DOC concentration in streams draining peatlands is highly variable, showing seasonal variation and short and intense DOC concentration peaks. This study aimed to statistically determine the variables driving stream DOC concentration variations at seasonal and event scales. Two mountainous peatlands (one fen and one bog) were monitored in the French Pyrenees to capture their outlet DOC concentration variability at a high-frequency rate (30?min). Abiotic variables including precipitation, stream temperature and water level, water table depth, and peat water temperature were also monitored at high frequency and used as potential predictors to explain DOC concentration variability. Results show that at both sites DOC concentration time series can be decomposed into a seasonal baseline interrupted by many short and intense peaks of higher concentrations. The DOC concentration baseline is driven, at the seasonal scale, by peat water temperature. At the event scale, DOC concentration increases are mostly driven by a rise in the water table within the peat at both sites. Univariate linear models between DOC concentration and peat water temperature or water table increases show greater efficiency at the fen site. Water recession times were derived from water level time series using master recession curve coefficients. They vary greatly between the two sites but also within one peatland site. They partly explain the differences between DOC dynamics in the studied peatlands, including peat porewater DOC concentrations and the links between stream DOC concentration and water table rise within the peatlands. This highlights that peatland complexes are composed of a mosaic of heterogeneous peat units distinctively producing or transferring DOC to streams.Rousseau, P., Piekarski, D.G., Capron, M., Domaracka, A., Adoui, L., Martín, F., Alcamí, M., Díaz-Tendero, S., Huber, B.A., 2020. Polypeptide formation in clusters of β-alanine amino acids by single ion impact. Nature Communications 11, 3818. formation of peptide bonds by energetic processing of amino acids is an important step towards the formation of biologically relevant molecules. As amino acids are present in space, scenarios have been developed to identify the roots of life on Earth, either by processes occurring in outer space or on Earth itself. We study the formation of peptide bonds in single collisions of low-energy He2+ ions (α-particles) with loosely bound clusters of β-alanine molecules at impact energies typical for solar wind. Experimental fragmentation mass spectra produced by collisions are compared with results of molecular dynamics simulations and an exhaustive exploration of potential energy surfaces. We show that peptide bonds are efficiently formed by water molecule emission, leading to the formation of up to tetrapeptide. The present results show that a plausible route to polypeptides formation in space is the collision of energetic ions with small clusters of amino acids.Ruebsam, W., Pieńkowski, G., Schwark, L., 2020. Toarcian climate and carbon cycle perturbations – its impact on sea-level changes, enhanced mobilization and oxidation of fossil organic matter. Earth and Planetary Science Letters 546, 116417. geochemistry and palynology reveal major organofacies changes in the marginal marine Polish Basin during the early Toarcian linked to changes in environmental conditions. Increasing water salinity and enhanced biomass contributions from phytoplankton, adopted to brackish conditions, attest to periodic marine ingressions into the paralic, hyposaline Polish Basin. Marine ingressions occurred upon reoccurring sea level rises concomitant with i) the Pliensbachian-Toarcian boundary carbon isotope excursion (Pl-Toa-CIE) and ii) the stepped Toarcian carbon isotope excursion (Toa-CIE), the latter marking the Toarcian Oceanic Anoxic Event (Toa-OAE). Strata with marine influences indicate an intermittent connection of the Polish Basin with the Tethys and attest to a close correlation between regional shoreline progradation and evolution of global climate and sea-level. Organic geochemistry indicated the link between sea level fluctuations and the Toa-CIEs, although in some areas of the Polish Basin the sea level rise was balanced by massively increased sediment delivery, caused by enhanced hydrological cycling that lead to intensified weathering and erosion in the hinterland. Enhanced hydrological cycling further led to the remobilization of organic matter of pre-Toarcian age. This points to erosion of older organic-rich rocks containing significant abundances of marine and terrestrial organic matter that was partly oxidized and re-deposited along with autochthonous Toarcian organic matter. Provenance areas identified point to two main sources, most likely Carboniferous terrestrial/paralic and Ordovician/Silurian marine sediments. Fossil organic matter should be considered as additional source in Toarcian carbon cycling, particularly in times of enhanced hydrological cycling, erosion and weathering. Remobilization of sedimentary fossil carbon has not been hitherto considered as a carbon source during the Toa-OAE.Ruhl, M., Hesselbo, S.P., Al-Suwaidi, A., Jenkyns, H.C., Damborenea, S.E., Mance?ido, M.O., Storm, M., Mather, T.A., Riccardi, A.C., 2020. On the onset of Central Atlantic Magmatic Province (CAMP) volcanism and environmental and carbon-cycle change at the Triassic–Jurassic transition (Neuquén Basin, Argentina). Earth-Science Reviews 208, 103229. Triassic–Jurassic transition is characterized by the end-Triassic mass extinction approximately synchronous with the onset of emplacement of the Central Atlantic Magmatic Province (CAMP), and associated with a major negative carbon-isotope excursion (CIE) affecting the ocean–atmosphere system. Here, we present new data (total organic carbon, pyrolysis analysis, carbon-isotopes from bulk organic matter, elemental mercury, and other elemental contents) from a southern-hemisphere Triassic–Jurassic boundary succession in the Neuquén Basin, Argentina. The end-Triassic mass extinction there coincides with a relatively small (2–3‰) negative CIE in bulk organic matter, and we present a model that suggests that extreme aridity across the western Pangaean landmass may have resulted in rather limited terrestrial organic-matter flux to the sedimentary realm in eastern Panthalassic marine basins, hypothetically reducing the magnitude of the observed negative CIE in δ13CTOC.Increased deposition of sedimentary Hg (and Hg/TOC and Hg/Zr) in the marine Neuquén Basin began stratigraphically before the negative CIE associated with the end-Triassic mass extinction, and thus before the commencement, in North America and Africa, of CAMP-related basaltic volcanism, but possibly coinciding with the early emplacement of CAMP-associated intrusives (dykes and sills). This relative chronology suggests thermal alteration of intruded country rocks and/or intrusive magmatic degassing of Hg as potential major sources of elevated Hg fluxes to the atmosphere at this time.The Neuquén Basin experienced the development of dysoxic–anoxic marine conditions across the Triassic–Jurassic transition, enabling increased preservation of organic matter. Simple mass-balance calculations show that enhanced carbon burial rates can explain the inferred evolution of the global exogenic carbon cycle across this time-interval.Ruiz-Morales, Y., Miranda-Olvera, A.D., Portales-Mart??nez, B.n., Dom??nguez, J.M., 2020. Experimental and theoretical approach to determine the average asphaltene structure of a crude oil from the Golden Lane (Faja de Oro) of Mexico. Energy & Fuels 34, 7985-8006. structural parameters and average molecular structures of the asphaltenes obtained from the Aguacate oilfield, located in the Golden Lane of Mexico, have been investigated combining experimental analysis and molecular simulation. The average molecular structural parameters of the polycyclic aromatic hydrocarbon (PAH) region, average number of fused aromatic rings (nFAR), average structural isomers in the polydispersity of the PAH core, average architecture, average molecular weight, and substituents in the PAH core have been determined by means of 13C single-pulse excitation (SPE) nuclear magnetic resonance (NMR) in combination with 13C distortionless enhancement by polarization transfer (DEPT)-135° experiments, 1H NMR, X-ray photoelectron spectroscopy, fluorescence emission, and matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry. The total energy of the PAH isomers and their fluorescence emission are calculated with density functional theory and ZINDO/S, respectively. The PAH region structural parameters determined are (a) Y-carbons (CY) or internal triple bridgehead aromatic carbons, (b) external peripheral aromatic carbon atoms at the junction of two fused rings (CAP3), (c) aromatic carbon atoms bonded to hydrogen atoms (CAH), (d) aromatic carbon atoms bonded to heteroatom (CAX), (e) aromatic carbon atoms bonded to hydrogen at the β position with respect to the heteroatom (CAHβX), and (f) substituted aromatic carbon atoms (CA-Caliph). The 13C NMR chemical shift ranges used for the different structural carbon atoms in the PAH core were obtained from our previous study [Ruiz-Morales, Y.; Miranda-Olvera, A. D.; Portales-Mart??nez, B.; Dom??nguez, J. M. Determination of 13C NMR Chemical Shift Structural Ranges for Polycyclic Aromatic Hydrocarbons (PAHs) and PAHs in Asphaltenes: An Experimental and Theoretical Density Functional Theory Study. Energy Fuels 2019, 33 (9), 7950?7970, DOI: 10.1021/acs.energyfuels.9b00182]. There is overlapping of the 13C SPE NMR signals of CAH, CY, and CAP3; therefore, quantitative 13C DEPT-135° NMR is necessary to determine the average CAH, and this value is subtracted from the quantitative 13C SPE NMR spectrum, where the signals overlap, to obtain the average number of bridgehead carbons (CY and CAP3). It is concluded that island is the predominant architecture of the Aguacate asphaltene, in accordance with the Yen–Mullins model. The PAH region contains nine fused aromatic rings (9FAR), where one of the rings is a thiophenic ring.Ruiz-Ruiz, P., Gómez-Borraz, T.L., Revah, S., Morales, M., 2020. Methanotroph-microalgae co-culture for greenhouse gas mitigation: Effect of initial biomass ratio and methane concentration. Chemosphere 259, 127418. work evaluated the effect of different initial biomass ratios in a co-culture of an alkaliphilic methanotrophic bacteria consortium (AMB) and the green microalga Scenedesmus obtusiusculus (GM) on the maximum CH4 specific biodegradation rate and global carbon uptake. The highest maximum specific biodegradation rate was 589 ± 0.01 mgCH4 gbiomass?1 d?1 obtained for a proportion of 3:1 AMB-GM (w w?1) and 8% of initial CH4 in the headspace. The methane degradation rate was 1.5 times lower than the value obtained solely by the AMB consortium, and it was associated with pH increases due to the evolved CO2 consumption by the microalga. Increased activity of the AMB consortium along the experiments was due to progressive adaptation. Massive sequencing revealed the presence of methanotrophic/methylotrophic species such as Methylocystis sp., Methylomicrobium sp., Methylophaga sp., and Hyphomicrobium sp. Successful complete methane and carbon dioxide uptake was obtained with the 3:1, 4:1, and 5:1 AMB-GM biomass ratios, while for the rest of the ratios tested, more than 70% of the initial methane was transformed into biomass and inorganic carbon. This study showed that methanotrophic-microalgal co-cultures lead to a promising strategy for greenhouse gases mitigation in one step.Sadegh Mazloom, M., Hemmati-Sarapardeh, A., Husein, M.M., Shokrollahzadeh Behbahani, H., Zendehboudi, S., 2020. Application of nanoparticles for asphaltenes adsorption and oxidation: A critical review of challenges and recent progress. Fuel 279, 117763. (NPs) have been recently recognized as effective asphaltenes adsorbents and deposition deterrents. The objective of this work is to provide a critical review and highlight the limitations of literature findings on NP use for asphaltenes adsorption and subsequent oxidation. Literature reports showed that asphaltenes uptake by NPs increases with increasing asphaltenes aromaticity and polarity. Moreover, NPs exhibit a higher selectivity to asphaltenes in the presence of other oil constituents such as resins. Composite NPs are superior asphaltenes deposition inhibitors owing to a synergy arising from attaching inorganic NPs to a hydrocarbon. It is worth noting that most of the asphaltenes uptake values were collected from model solutions, and were calculated based on UV–Vis measurements, which have been recently shown not to be very reliable. Acidic NPs and small size NPs are considered better asphaltenes adsorbents, whereas basic NPs and large size NPs are reported as better asphaltenes oxidation promoters. In situ combustion, which is an important enhanced oil recovery method, can be improved in the presence of NPs. Two mechanisms have been proposed to explain the rapid oxidation of adsorbed asphaltenes; namely mass transfer enhancement and catalytic effect. There is a stronger evidence in support of enhanced asphaltenes exposure to the mass of flowing air. Lastly, the impact of different reservoir conditions on asphaltenes adsorption is presented. The findings of this review improve our understanding of asphaltenes adsorption and the oxidation of adsorbed asphaltenes as well as the challenges hindering the effective use of NPs in asphaltenes related problems at both laboratory and field scales.Sadi, M., Kananpanah, S., Bayat, M., 2020. Adaptive neuro fuzzy inference system to predict average asphaltene particle diameter case study: in thermal de-asphalting process. Petroleum Science and Technology 38, 542-549. thermal de-asphalting procedure, where asphaltene particles are aggregated through heating crude oil at an elevated temperature, predicting the asphaltene particles? diameter is of major importance. In this study, thermal de-asphalting process is modeled using adaptive neuro fuzzy inference system by considering isolating temperature, crude oil API and asphaltene content as inputs to predict asphaltene particles? average diameter. The experimental data measured in a custom built thermal de-asphalting set-up, are applied to construct neuro fuzzy model structure. The average relative error of proposed model, for all data points is 3.06%, indicating an excellent agreement between model predictions and experimental values.Saint-Vincent, P.M.B., Sams, J.I., Hammack, R.W., Veloski, G.A., Pekney, N.J., 2020. Identifying abandoned well sites using database records and aeromagnetic surveys. Environmental Science & Technology 54, 8300-8309. and natural gas are primary sources of energy in the United States. Improved drilling and extracting techniques have led to a renewed interest in historic oil and gas fields, but limited records of legacy wells make new drilling efforts more difficult, as abandoned wells may provide conduits for liquids and gases to migrate into groundwater reservoirs or the atmosphere. Well finding using aeromagnetic surveys pinpoints the location of steel-cased wells, detecting both active and abandoned wells, including buried casings lacking aboveground markers. Here, we present six aeromagnetic surveys conducted in Pennsylvania and Wyoming as case studies, comparing the magnetic points to locations known in databases. In all study sites, more magnetic points were detected than recorded in databases. Based on differences between theoretical database well counts and the actual number of wells detected in surveys, we estimated the total number of wells in Pennsylvania to be 395?000–466?000 and 181?000–182?000 in Wyoming. Extrapolating to the national level, we estimate the average number of wells in the continental United States is 6.04 ± 19.97 million wells with 1.16 ± 3.84 million of those designated as abandoned wells, within the range of previous abandoned well count estimations. Although aeromagnetic surveys are limited to detecting steel-cased wells and do not differentiate sites based on well status, this study nevertheless demonstrates the utility of aeromagnetic surveys in well finding efforts across the country and shows limitations in database records of oil and natural gas wells.Sakr, A.A., Ghaly, M.F., Edwards, H.G.M., Ali, M.F., Abdel-Haliem, M.E.F., 2020. Involvement of Streptomyces in the deterioration of cultural heritage materials through biomineralization and bio-pigment production pathways: A review. Geomicrobiology Journal 37, 653-662. are involved in the deterioration of cultural heritage materials through several pathways, the most important of these are biomineralization and bio-pigment production. The biomineralization pathway can occur through the precipitation of calcite, silica, barytes, hydromagnesite and iron compounds on colonized paintings and on stone surfaces with paintings in relief. Streptomyces biomineralize boron although it was confirmed in biodeterioration of cultural heritage materials. The other pathway occurs via bio pigment production and the most common of these biopigments are melanin with colors ranging from black through brown to olive, carotenoids with colors ranging from red, yellow, and pink through to violet and thirdly, actinorhodin-related blue pigments.Salehpour, M., Riazi, M., Malayeri, M.R., Seyyedi, M., 2020. CO2-saturated brine injection into heavy oil carbonate reservoirs: Investigation of enhanced oil recovery and carbon storage. Journal of Petroleum Science and Engineering 195, 107663. fuel to a large extent is still expected to dominate the global energy demands for the next few decades. An inevitable and detrimental consequence of such source of energy is though the emission of hazardous CO2. Therefore, technologies that can utilize and permanently store the emitted CO2 are of great interest for the energy industry. A viable large-scale CO2 utilization and storage technology is the CO2 enhanced oil recovery (EOR) technique. However, this technique mostly lacks a good volumetric sweep efficiency at the reservoir-scale. An alternative option is CO2-saturated (carbonated) water injection (CWI). Although the oil recovery and CO2 storage potential of CWI for light and medium crude oil systems have been extensively studied, only a few studies investigated carbon storage particularly in heavy oil reservoirs. As such, this study through an experimental approach provides more insights into this subject. The results show that the high asphaltene contents of the used heavy crude oil led to formation of in-situ water-in-oil emulsions during both waterflooding and CWI. Emulsions decreased the flow path area of injection fluid and blocked some pores and throats, which consequently led to local flow diversions to un-swept areas of the porous media and an improvement in oil recovery. The emulsion-induced local flow diversions during CWI improved the effectiveness of oil recovery mechanisms of CWI by bringing more residual oil in contact with carbonated brine. Both secondary and tertiary CWI led to 24% and 20% higher oil recovery compared to conventional waterflooding, respectively. Furthermore, during secondary and tertiary CWI around 22% and 32% of the total injected CO2 were stored in the core plugs mostly by solubility trapping in the residual oil. The CO2 utilization factor increased over the carbonated brine injection period indicating higher CO2 needs to be injected for producing a barrel of oil.Sanyal, P., Ray, R., Paul, M., Gupta, V.K., Acharya, A., Bakshi, S., Jana, T.K., Mukhopadhyay, S.K., 2020. Assessing the dynamics of dissolved organic matter (DOM) in the coastal environments dominated by mangroves, Indian sundarbans. Frontiers in Earth Science 8, 218. doi: 10.3389/feart.2020.00218. transport from coastal wetlands (“outwelling”), together with riverine fluxes, provide the most important sources of terrigenous organic matter (OM) to the ocean. The flux of dissolved organic carbon (DOC) from the mangrove swamps accounts for 10% of the terrestrial DOC flux to the coastal water. This study examines the sources, distribution, and export of dissolved OM at interannual, seasonal, and diurnal bases along the estuaries located at the Sundarbans, the world’s largest deltaic mangrove and heritage site. Sampling was carried out from the riverine (Hooghly) and mangrove-dominated tidal estuaries (Saptamukhi, Thakuran, Matla), covering all three seasons (pre-monsoon, monsoon, and post-monsoon) during 2012–2017. DOC varied at a broad range, from 109 to 462 μM (n = 146), with higher concentration observed in the Hooghly (383 ± 120 μM, n = 35) than the mangrove estuaries (246 ± 82 to 266 ± 120 μM, n = 111). Non-conservative mixing of DOC along the salinity gradient attested to mangrove input, particularly in the polyhaline waters. Upper and mid estuarine zones of the mangrove estuaries showed slightly higher DOC concentration (270 ± 92 μM, n = 84, salinity range 18–25) than in the mouth (250 ± 85 μM, n = 27, salinity range 26–27), because of the dilution with marine waters having low DOC concentration and shorter water residence time downstream. Seasonally, higher DOC concentration during the post-monsoon might be linked to higher litterfall, promoting leaching of organic compounds to the water. In that connection, colored dissolved organic matter (CDOM) could be a by-product of mangrove litter leaching, and its absorption coefficient (at 350 nm) exhibited non-conservative mixing pattern at wide ranges from 2.5 to 7.6 m?1 (n = 40). CDOM enrichment was observed in the surface water during the low tide when outwelling maximized. Overall, the central and eastern parts of the Indian Sundarbans showed enrichment of more terrigenous type CDOM (evident from optical proxies, e.g., S275–295 and SUVA254) than the western part, probably due to greater mangrove productivity in the eastern side. Flux estimates of DOM resulted in higher yield and export of mangrove-derived DOC but lower export of CDOM to the Bay of Bengal as compared to their riverine transport.Sass, K., Güllert, S., Streit, W.R., Perner, M., 2020. A hydrogen-oxidizing bacterium enriched from the open ocean resembling a symbiont. Environmental Microbiology Reports 12, 396-405. new autotrophic hydrogen‐oxidizing Chromatiaceae bacterium, namely bacterium CTD079, was enriched from a water column sample at 1500?m water depth in the southern Pacific Ocean. Based on the phylogeny of 16S rRNA genes, it was closely related to a scaly snail endosymbiont (99.2% DNA sequence identity) whose host so far is only known to colonize hydrothermal vents along the Indian ridge. The average nucleotide identity between the genomes of CTD079 and the snail endosymbiont was 91%. The observed differences likely reflect adaptations to their specific habitats. For example, CTD079 encodes additional enzymes like the formate dehydrogenase increasing the organism's spectrum of energy generation pathways. Other additional physiological features of CTD079 included the increase of viral defence strategies, secretion systems and specific transporters for essential elements. These important genome characteristics suggest an adaptation to life in the open ocean.Savinykh, Y.V., Stakhina, L.D., 2020. The influence of integrated technologies for enhanced oil recovery on the composition and properties of oil produced in the Usa field. Petroleum Chemistry 60, 675-682. influence and effectiveness of technologies aimed at enhancing oil recovery on changes in the composition and properties of the extracted heavy oil from the Usa field have been studied. The injection into the reservoir of oil-displacing compositions containing surfactants, together with cyclic steam simulation (CSS), leads to an increase in the flow rate due to additional washing out of the residual oil and the involvement of new tight stringers that have not been previously engaged. The processes occurring in the reservoir can be monitored by following the change in the composition and properties of the produced oil.Schefu?, E., Dupont, L.M., 2020. Multiple drivers of Miocene C4 ecosystem expansions. Nature Geoscience 13, 463-464. on: Polissar, P.J., Rose, C., Uno, K.T. et al. Synchronous rise of African C4 ecosystems 10 million years ago in the absence of aridification. Nat. Geosci. 12, 657–660 (2019). Replied to Comment: Polissar, P.J., Rose, C., Uno, K.T., Phelps, S.R., deMenocal, P., 2020. Reply to: Multiple drivers of Miocene C4 ecosystem expansions. Nature Geoscience 13, 465-467.The drivers of C4 grassland expansions in the Miocene are a subject of long-term debate; initial scenarios invoked the falling atmospheric partial pressure of CO2 (p CO 2 pCO2) based on the CO2-concentrating mechanism of C4 plants1, whereas later studies favoured regional responses to global changes in atmospheric circulation and hydroclimate based on the asynchronous timing of C4 geographical expansions and the absence of substantial changes in reconstructed atmospheric p CO 2 pCO2 levels (Fig. 1a)2. Polissar et al.3 argue that C4 ecosystems in Africa expanded synchronously in Africa in the absence of aridification and probably due to falling CO2 levels. We question their interpretation of the data and thus their conclusions as outlined below. Consequently, we do not find evidence that C4 plant expansions in different parts of Africa were synchronously driven by declining CO2 levels.In conclusion, we regard the interpretation of the δ13C rise of the n-C35 alkane without substantial increases in the δ13C of the n-C29 to n-C33 alkanes as being indicative of C4 plant expansion at 10?Ma as speculative. Aridification cannot be ruled out as driver of C4 plant expansion around 8–7?Ma on the basis of the presented data. In particular, the existing data on low and stable atmospheric CO2 concentrations during the Miocene (Fig. 1a) contradict the idea that ‘declining atmospheric CO2 levels were a direct cause of the C4 grassland expansion’3. In contrast, we regard the time-transgressive expansion of C4 ecosystems in various regions (see fig. 3e of ref. 3) a consequence of increasing meridional temperature gradients (see fig. 3a of ref. 3 and ref. 14) with asynchronous and progressive responses at different locations due to site-specific sensitivities towards increasing changes in seasonality, moisture availability and sources.Schlanser, K.M., Diefendorf, A.F., West, C.K., Greenwood, D.R., Basinger, J.F., Meyer, H.W., Lowe, A.J., Naake, H.H., 2020. Conifers are a major source of sedimentary leaf wax n-alkanes when dominant in the landscape: Case studies from the Paleogene. Organic Geochemistry 147, 104069. wax n-alkanes are valuable paleoclimate proxies because their carbon (δ13C) and hydrogen (δ2H) isotopes track biological and environmental processes. Angiosperms produce higher concentrations of n-alkanes than conifers, with some exceptions. Vegetation source is significant because in similar climates, both taxa produce n-alkanes with unique δ13C and δ2H values due to different physiological strategies. To test whether conifers contribute significantly to sediment n-alkanes and result in distinctive isotopic signatures, we collected sediment samples from a suite of Paleogene paleobotanical sites in North America with high and low conifer abundances. To disentangle the source of sediment n-alkanes, we measured the δ13C values of nonsteroidal triterpenoids (angiosperm biomarkers) and tricyclic diterpenoids (conifer biomarkers) to determine angiosperm and conifer end member δ13C values. We then compared these end member values to n-alkane δ13C values for each site to estimate their major taxon sources. At sites dominated by conifer macrofossils, δ13C values of n-alkanes indicate a conifer source. At mixed conifer and angiosperm sites, conifer contributions increased with increasing n-alkane chain length. At sites where conifers were not as abundant as angiosperms, the δ13C values of n-alkanes indicate a predominant angiosperm source with some sites showing a conifer contribution to n-C33 and n-C35 alkanes. This suggests that conifers in the Paleogene contributed to longer chain n-alkanes (n-C33 and n-C35) even when not the dominant taxa, but this likely differs for other geographic locations and taxa. This new approach allows unique floral information to be extracted when chain length is carefully considered in the absence of other paleobotanical data and necessitates having some paleovegetation constraints when interpreting carbon and hydrogen isotopes of plant wax-derived n-alkanes.Schrumpf, M., Kaiser, K., Mayer, A., Hempel, G., Trumbore, S., 2020. Age distribution, extractability, and stability of mineral-bound organic carbon in central European soils. Biogeosciences Discussions 2020, 1-32. largest share of total soil organic carbon (OC) is associated with minerals. The portions and turnover of stable and faster cycling mineral-associated carbon (MOC) as well as the determining factors across different soils and soil depths are still unknown. Bioavailability of MOC is supposedly regulated by desorption but instead, its stability was so far mostly tested by exposure to chemical oxidation. Therefore, we determined the extractability of MOC into a mixture of 0.1?M?NaOH and 0.4?M?NaF as a measure for maximal potential desorbability, and compared it with maximal potential oxidation in heated H2O2. We selected samples of three soil depth increments (0–5?cm, 10–20?cm, 30–40?cm) of five typical soils of the mid-latitudes, differing contents of clay and pedogenic oxides, and being under different land use. Extracts and residues were analyzed for OC and 14C contents, and further chemically characterized by CPMAS-13C-NMR. We hypothesized NaF-NaOH extraction to remove less and younger MOC than H2O2 oxidation, and extractable MOC to be less and relatively older in subsoils and soils with high contents of pedogenic oxides.A surprisingly constant portion of 58?±?11?% (standard deviation) of MOC was extractable across soils, independent of depths, mineral assemblage, or land use. NMR spectra revealed strong similarities of the extracted organic matter, with more than 80?% of OC in the O/N alkyl and alkyl C region. Total MOC amounts were linked to the content of pedogenic oxides across sites, independent of variations in total clay. The uniform MOC desorption could therefore be the result of pedogenic oxides dominating the overall response of MOC to extraction.While bulk MO14C values suggested differences in OC turnover between sites, these were not linked to differences in MOC extractability. As expected, OC contents of residues had smaller 14C contents than extracts, suggesting that non-extractable OC is older. However, 14C contents of extracts and residues were strongly correlated and proportional to bulk MO14C, but not dependent on mineralogy. Also along soil profiles, where increasing MOC ages indicate slower turnover with depth, neither MOC extractability nor differences in 14C between extracts and residues changed. Increasing bonding strength with soil depths did therefore not cause the 14C depth gradients in the studied soils.Although H2O2 removed 90?±?8?% of the MOC, the 14C content of the OC removed was similar to that of the NaF-NaOH-extracted OC, while oxidation residues were much more 14C-depleted. Different chemical treatments apparently remove OC of the same continuum, leaving increasingly older residues behind the more OC being removed. Different from the extractions, higher contents of pedogenic oxides seemingly slightly increased the oxidation-resistance of MOC, but this higher H2O2-resistance did not coincide with older MOC or oxidation residues.Our results indicate that total MOC was dominated by OC interactions with pedogenic oxides rather than clay minerals, so that no difference in MOC extraction in NaF/NaOH, and thus, bond type or strength between clay-rich and poor sites was detectable. This suggests that site-specific differences in MO14C and their depth declines are driven by the accumulation and exchange rates of OC at mineral surfaces. Accordingly, future research on M14OC should focus on soil and ecosystem properties driving dissolved organic matter formation, composition and transport along soil profiles.Schulze, B., Bader, T., Seitz, W., Winzenbacher, R., 2020. Column bleed in the analysis of highly polar substances: an overlooked aspect in HRMS. Analytical and Bioanalytical Chemistry 412, 4837-4847. close the “analytical gap” in the liquid chromatographic (LC) analysis of highly polar substances, two techniques which have been suggested earlier were tested in terms of retention factors and detection limits: hydrophilic interaction liquid chromatography (HILIC) and mixed-mode chromatography (MMC). A substance mix of 55 analytes ranging from logD ??8.2 to 3.4 and 17 different LC columns, also comprising additional reversed-phase columns were used. Contrary to most reversed-phase columns, column bleed has been identified as an important factor, which may cause serious restrictions during high-resolution mass spectrometric detection (HRMS). We found that highly abundant background masses continuously eluting from the columns heavily influence ion transmission to the detector. As a result, the linear dynamic range as well as the sensitivity decreases and thus limits the HRMS applicability of some columns. We therefore recommend a thorough investigation of ion transmission during HRMS method development. This will help to maintain the high potential of HRMS in terms of qualitative and quantitative screening analysis.Schulze, S., Paschke, H., Meier, T., Muschket, M., Reemtsma, T., Berger, U., 2020. A rapid method for quantification of persistent and mobile organic substances in water using supercritical fluid chromatography coupled to high-resolution mass spectrometry. Analytical and Bioanalytical Chemistry 412, 4941-4952. and mobile organic substances (PM substances) are a threat to the quality of our water resources. While screening studies revealed widespread occurrence of many PM substances, rapid trace analytical methods for their quantification in large sample sets are missing. We developed a quick and generic analytical method for highly mobile analytes in surface water, groundwater, and drinking water samples based on enrichment through azeotrope evaporation (4?mL water and 21?mL acetonitrile), supercritical fluid chromatography (SFC) coupled to high-resolution mass spectrometry (HRMS), and quantification using a compound-specific correction factor for apparent recovery. The method was validated using 17 PM substances. Sample preparation recoveries were between 60 and 110% for the vast majority of PM substances. Strong matrix effects (most commonly suppressive) were observed, necessitating a correction for apparent recoveries in quantification. Apparent recoveries were neither concentration dependent nor dependent on the water matrix (surface or drinking water). Method detection and quantification limits were in the single- to double-digit ng?L?1 ranges, precision expressed as relative standard deviation of quadruplicate quantifications was on average <?10%, and trueness experiments showed quantitative results within ±?30% of the theoretical value in 77% of quantifications. Application of the method to surface water, groundwater, raw water, and finished drinking water revealed the presence of acesulfame and trifluoromethanesulfonic acid up to 70 and 19?μg?L?1, respectively. Melamine, diphenylguanidine, p-dimethylbenzenesulfonic acid, and 4-hydroxy-1-(2-hydroxyethyl)-2,2,6,6-tetramethylpiperidine were found in high ng?L?1 concentrations.Sen, K., Dash, P.S., 2020. Quantum chemical perspective of coal molecular modeling: A review. Fuel 279, 118539. the utility of coal in many practical industrial processes, this review aims to discuss the key developments and thereby significant contributions from quantum chemistry investigations to the demystification of complex coal systems and chemistry thereof. The scope does not include a comprehensive review of all the work done till date. While it addresses our current state of understanding, utilization of quantum chemical techniques in unravelling several fundamental features is also discussed. The possibility of occurrence of a variety of decarboxylation reactions in low-rank coals is explained in terms of varying activation energies of the processes. It can be seen that areas of coal liquefaction and carbonization experience significant shortage of novel applications of quantum chemical methods. Thus, these areas have longstanding fundamental questions which remain unanswered. Considering gasification of coal with carbon dioxide, the efficiency of the process is found to be strongly dependent on the chemical nature of the active sites for CO2 adsorption as well as surface active site concentration. The calculations also shed light into the reason behind enhanced rate of catalytic desorption of CO while, interestingly, the activation energy for both the uncatalyzed and catalyzed reaction routes remain unaltered. Low-temperature chemisorption of O2 on coal surface is also successfully explained from the calculations. Despite all these efforts, varying conditions for coal gasification and combustion still require advanced analysis. Coal rank and coal structural features call for increasing and judicious modelling that can ultimately contribute to the advent of advanced coal technology.Sermoud, V.M., Barbosa, G.D., Barreto, A.G., Tavares, F.W., 2020. Quenched solid density functional theory coupled with PC-SAFT for the adsorption modeling on nanopores. Fluid Phase Equilibria 521, 112700. functional theory (DFT) models appear as tools for modeling the phenomenon of adsorption in nano-confinement environments. The challenges of DFT approaches are to take the acuity observed in molecular simulation with a notably lower computational cost. Therefore, the model has the advantage to take into account different contributions, which can become necessary depending on the system to be studied. Here, we present the PC-SAFT-QSDFT for a better evaluation of confined fluids properties in a wide pressure range, aiming its application in the analysis of the phase transitions, hysteresis loops, and isosteric enthalpy of adsorption. Accordingly, we tested the model in a system formed by mono-segmented species, and after in systems composed by multi-segmented substances. The results obtained for the latter show that the model adequately represents experimental data. The evaluation of the isosteric enthalpy of adsorption shows consistent results.Seto, M., Iwasa, Y., 2020. Microbial material cycling, energetic constraints and ecosystem expansion in subsurface ecosystems. Proceedings of the Royal Society B: Biological Sciences 287, 20200610. harvest energy from chemical reactions, microbes engage in diverse catabolic interactions that drive material cycles in the environment. Here, we consider a simple mathematical model for cycling reactions between alternative forms of an element (A and Ae), where reaction 1 converts A to Ae and reaction 2 converts Ae to A. There are two types of microbes: type 1 microbes harness reaction 1, and type 2 microbes harness reaction 2. Each type receives its own catabolic resources from the other type and provides the other type with the by-products as the catabolic resources. Analyses of the model show that each type increases its steady-state abundance in the presence of the other type. The flux of material flow becomes faster in the presence of microbes. By coupling two catabolic reactions, types 1 and 2 can also expand their realized niches through the abundant resource premium, the effect of relative quantities of products and reactants on the available chemical energy, which is especially important for microbes under strong energetic limitations. The plausibility of mutually beneficial interactions is controlled by the available chemical energy (Gibbs energy) of the system. We conclude that mutualistic catabolic interactions can be an important factor that enables microbes in subsurface ecosystems to increase ecosystem productivity and expand the ecosystem.Shalaby, M.R., Malik, O.A., Lai, D., Jumat, N., Islam, M.A., 2020. Thermal maturity and TOC prediction using machine learning techniques: case study from the Cretaceous–Paleocene source rock, Taranaki Basin, New Zealand. Journal of Petroleum Exploration and Production Technology 10, 2175-2193. maturity, organic richness and kerogen typing are very important parameters to be evaluated for source rock characterization. Due to the difficulties of high cost geochemical analyses and the unavailability of rock samples, it was necessary to examine and test many different method and techniques to help in the prediction of TOC values as well as other maturity indicators in case of missing or absence of geochemical data. Integrated study of machine learning techniques and well-log data has been applied on Cretaceous–Paleocene formations in the Taranaki Basin, New Zealand. A novel approach of maturity prediction using Tmax and vitrinite reflectance (VR%) is the first and preliminary objective of this research. Moreover, the organic richness or the total organic carbon (TOC) content has been predicted as well. Geochemical and well-log data collected from the Cretaceous Rakopi and North Cape formations and Paleocene Mangahewa Formation have been processed and prepared to apply the machine learning techniques. Five machine learning techniques, namely Bayesian regularization for feed-forward neural networks (BRNNs), random forest (RF), support vector machine (SVM) for regression, linear regression (LR) and Gaussian process regression (GPR), were employed for prediction of TOC, Tmax and VR, and their results have been compared. For TOC prediction, the best model achieved the coefficient of determination (R2) value of 0.964 using RF model. For Tmax prediction, BRNN with one hidden layer achieved the R2 value of 0.828. BRNN with two hidden layers produced the best model for VR prediction achieving R2?=?0.636. A comparison of five ML techniques showed that all of these techniques performed exceedingly well for TOC prediction with a value of R2?>?0.96. In contrast, BRNN with one hidden layer was the only ML technique able to achieve R2?>?0.8 for Tmax and BRNN with two hidden layers was the only ML technique able to achieve R2?>?0.6 for VR prediction. Therefore, this research provides a strong empirical evidence that ML techniques can capture the nonlinear relationship between the well-log data and TOC as well as the maturity indicators which may not be fully understood by existing linear models.Shan, C.a., Zhang, T., Liang, X., Hu, R., Zhao, W., 2020. Nanopore structure characteristics of high-rank vitrinite- and inertinite-coal. Acta Petrolei Sinica 41, 723-736. high-rank coal samples with the vitrinite content greater than 75% and seven high-rank coal samples with the inertinite content greater than 75% were selected from coalbed methane wells in the Junlian area in the southern Sichuan Basin. Using scanning electron microscopy, in combination with low temperature nitrogen adsorption experiment and physical property test analysis based on nuclear magnetic resonance, this paper systematically, qualitatively and quantitatively compare and study the nanopore structure characteristics of high-rank vitrinite- and inertinite-rich coal. The results show that primary pores (vegetable tissue pores) are more developed in the inertinite than in the vitrinite, while epigenetic pores (stomata) and exogenous pores (breccia pores and fracture pores) are more developed in the vitrinite. Both the high-rank vitrinite- and inertinite-rich coal has a complex nano-scale pore structure, but the pore morpholohy of high-rank inertinite-rich coal is more complex and special (the ink bottle-shaped pores are more developed). There are significant differences in the forms of the adsorption curves of high-rank vitrinite- and inertinite-rich coal at the initial stage (p/p0<0.05). The adsorption curve of the inertinite-rich coal samples showed a rapid increase at the initial stage (p/p0<0.05), and that of the vitrinite-rich coal samples rose slowly at this stage. Thus, the inertinite contains more molecular pores with a pore size of less than 0.64 nm. The average pore specific surface area, average pore volume and nitrogen adsorption of high-rank inertinite-rich coal are larger than those of the high-rank vitrinite-rich coal, and their average pore diameter of nanopores is nearly the same. The pore diameters of 2-4 nm play a major role in the pore specific surface area of high-rank vitrinite- and inertinite-rich coal. It can be speculated that pores with the pore diameter less than 4 nm account for the largest proportion of pores at all levels in those two kinds of coal. Pores with the average pore diameter larger than 10 nm in high-rank vitrinite-rich coal have a significant contribution to pore volume, while those with the average pore diameter greater than 2 nm have an obvious contribution. It is concluded that the nanopores with a pore diameter between 2 nm and 10 nm are more developed in the inertinite. The porosity, permeability and irreducible water saturation in the vitrinite and inertinite are nealy the same, and the porosity is exponentially positively correlated with the permeability. There is no obvious correlation between the irreducible water saturation and the porosity in high-rank vitrinite-rich coal, but there is a good negative correlation between the irreducible water saturation and the permeability. There is an obvious negative correlation between the irreducible water saturation, porosity and permeability in high-rank inertinite-rich coal.Shao, J., Stott, L.D., Menviel, L., Ridgwell, A., ?dalen, M., Mohtadi, M., 2020. The atmospheric bridge communicated the δ13C decline during the last deglaciation to the global upper ocean. Climate of the Past Discussions 2020, 1-28. the early last glacial termination (17.2–15?ka) atmospheric δ13C declined sharply by 0.3–0.4?‰ as atmospheric pCO2 rose. This was the initial part of the atmospheric δ13C excursion that lasted for multiple thousand years. A similar δ13C decline has been documented in marine proxy records from both surface and thermocline-dwelling planktic foraminifera. The foraminiferal δ13C decline has previously been attributed to a flux of respired carbon from the deep ocean that was subsequently transported within the upper ocean (i.e. bottom up transport) to sites where the signal is recorded. Here, we provide modeling evidence that when respired carbon upwells in the Southern Ocean, negative δ13C anomalies in the global upper ocean were instead transferred from the atmosphere (i.e. top down transport). Due to this efficient atmospheric bridge, the pathway of δ13C transport was likely to be different from nutrient transport during the early deglaciation. This implies that the usage of planktic δ13C records for identifying the carbon source(s) responsible for the atmospheric pCO2 rise during the early deglaciation is limited. The model results also suggest that thermocline waters in upwelling systems like the eastern equatorial Pacific, and even upper deep waters above 2000?m, can be affected by this atmospheric bridge during the early deglaciation. Our results imply that caution must be applied when interpreting early deglacial marine δ13C records from depths that are potentially affected by the atmosphere.Shen, Z., Zhang, Z., Li, T., Yao, Q., Zhang, T., Chen, W., 2020. Facet-dependent adsorption and fractionation of natural organic matter on crystalline metal oxide nanoparticles. Environmental Science & Technology 54, 8622-8631. organic matter (NOM) and crystalline metal oxide nanoparticles are both prevalent in natural aquatic environments, and their interactions have important environmental and biogeochemical implications. Here, we show that these interactions are significantly affected by an intrinsic property of metal oxide nanocrystals, the exposed facets. Both anatase (TiO2) and hematite (α-Fe2O3) nanocrystals, representing common engineered and naturally occurring metal oxides, exhibited apparent facet-dependent adsorption of humic acid and fulvic acid. This facet-dependent binding was primarily driven by surface complexation between the NOM carboxyl groups and surficial metal atoms. Thus, the adsorption affinity of different-faceted nanocrystals was determined by the atomic arrangements of crystal facets that controlled the activity of metal atoms and, consequently, the ligand exchange and binding configuration of the carboxyl groups in the first hydration shell of nanocrystals. Distinct facet-dependent fractionation patterns were observed during adsorption of NOM components, particularly the low-molecular-weight and photorefractory constituents. The molecular fractionation of NOM between water and metal oxide nanoparticles was dictated by the combined effects of facet-dependent metal complexation, hydrophobic interaction, and steric hindrance and may significantly influence the NOM-driven processes occurring both in aqueous phases and at water–nanoparticle interfaces.Shi, J.-T., Wu, J.-Y., Sun, Z., Xiao, Z.-H., Liu, C., Sepehrnoori, K., 2020. Methods for simultaneously evaluating reserve and permeability of undersaturated coalbed methane reservoirs using production data during the dewatering stage. Petroleum Science 17, 1067-1086. this work, a flowing material balance equation (FMBE) is established for undersaturated coalbed methane (CBM) reservoirs, which considers immobile free gas expansion effect at the dewatering stage. Based on the established FMBE, five straight-line methods are proposed to determine the control area, initial water reserve, initial free gas reserve, initial adsorbed gas reserve, original gas in place, as well as permeability at the same time. Subsequently, the proposed FMBE methods for undersaturated CBM reservoirs are validated against a reservoir simulation software with and without considering free gas expansion. Finally, the proposed methods are applied in a field case when considering free gas expansion effect. Validation cases show that the straight-line relationships for the proposed five FMBE methods are excellent, and good agreements are obtained among the actual reserves and permeabilities and those evaluated by the proposed five FMBE methods, indicating the proposed five FMBE methods are effective and rational for CBM reservoirs. Results show that a small amount of free gas will result in a great deviation in reserve evaluation; hence, the immobile free gas expansion effect should be considered when establishing the material balance equation of undersaturated CBM reservoirs at the dewatering stage.Shi, Z., Allison, S.D., He, Y., Levine, P.A., Hoyt, A.M., Beem-Miller, J., Zhu, Q., Wieder, W.R., Trumbore, S., Randerson, J.T., 2020. The age distribution of global soil carbon inferred from radiocarbon measurements. Nature Geoscience 13, 555-559. contain more carbon than the atmosphere and vegetation combined. An increased flow of carbon from the atmosphere into soil pools could help mitigate anthropogenic emissions of carbon dioxide and climate change. Yet we do not know how quickly soils might respond because the age distribution of soil carbon is uncertain. Here we used 789 radiocarbon (?14C) profiles, along with other geospatial information, to create globally gridded datasets of mineral soil ?14C and mean age. We found that soil depth is a primary driver of ?14C, whereas climate (for example, mean annual temperature) is a major control on the spatial pattern of ?14C in surface soil. Integrated to a depth of 1?m, global soil carbon has a mean age of 4,830?±?1,730?yr, with older carbon in deeper layers and permafrost regions. In contrast, vertically resolved land models simulate ?14C values that imply younger carbon ages and a more rapid carbon turnover. Our data-derived estimates of older mean soil carbon age suggest that soils will accumulate less carbon than predicted by current Earth system models over the twenty-first century. Reconciling these models with the global distribution of soil radiocarbon will require a better representation of the mechanisms that control carbon persistence in soils.Shillito, L.-M., Blong, J.C., Green, E.J., van Asperen, E.N., 2020. The what, how and why of archaeological coprolite analysis. Earth-Science Reviews 207, 103196. are a highly informative but still underutilized proxy for understanding past environments, palaeodiets, and ancient human health. Here we provide a critical review of the history and current state of research in human coprolite analysis encompassing macroscopic, microscopic, and biomolecular approaches. We present new data from a number of key sites which demonstrates how new multiscalar, multiproxy approaches can provide unique archaeological insights. Coprolites should be routinely collected and examined during excavations and integrated with other archaeological and palaeoecological evidence. Future research needs to focus on better understanding coprolite formation as well as pre- and post- depositional taphonomy. This can be achieved through interdisciplinary collaboration between geoarchaeology and organic geochemistry.Shillito, L.-M., Whelton, H.L., Blong, J.C., Jenkins, D.L., Connolly, T.J., Bull, I.D., 2020. Pre-Clovis occupation of the Americas identified by human fecal biomarkers in coprolites from Paisley Caves, Oregon. Science Advances 6, eaba6404. and how people first settled in the Americas is an ongoing area of research and debate. The earliest sites typically only contain lithic artifacts that cannot be directly dated. The lack of human skeletal remains in these early contexts means that alternative sources of evidence are needed. Coprolites, and the DNA contained within them, are one such source, but unresolved issues concerning ancient DNA taphonomy and potential for contamination make this approach problematic. Here, we use fecal lipid biomarkers to demonstrate unequivocally that three coprolites dated to pre-Clovis are human, raise questions over the reliance on DNA methods, and present a new radiocarbon date on basketry further supporting pre-Clovis human occupation.Shiraishi, F., Omori, T., Tomioka, N., Motai, S., Suga, H., Takahashi, Y., 2020. Characteristics of CaCO3 nucleated around cyanobacteria: Implications for calcification process. Geochimica et Cosmochimica Acta 285, 55-69. evaluate the influences of cyanobacterial extracellular polymeric substances (EPS) on CaCO3 precipitation, calcification experiments were conducted for 48?h (initial values of calcite saturation state and equilibrium CO2 partial pressure were ～5-fold and ～600 μatm, respectively) using cultures of four filamentous strains (Leptolyngbya sp. (NIES-2104), Scytonema sp. (NIES-2130), Phormidium ambiguum (NIES-2119), and Spirulina subsalsa (NIES-598)). All cultures induced CaCO3 precipitation mainly by photosynthesis to form mono-/poly crystalline calcite and amorphous calcium carbonate (ACC) around them. These features suggested a CaCO3 nucleation process via an ACC precursor phase on negatively charged substances generated by cyanobacteria (i.e., cell walls, EPS, and oxygen bubbles). The characteristics of the precipitated CaCO3 were strongly influenced by the surface properties of the cyanobacteria. For Leptolyngbya, which lacks EPS, a small number of CaCO3 was nucleated onto the smooth surface of negatively charged cell walls and entire cells were incorporated into a large single crystal of calcite. For Scytonema and Phormidium, which possess EPS sheaths, a relatively large number of CaCO3 was nucleated onto the rough surface of negatively charged sheaths, and their sheaths were encrusted and partially impregnated by calcite crystals. For Spirulina, which possesses a loose EPS matrix, CaCO3 nucleation was scarce and restricted to the surface of negatively charged oxygen bubbles stabilized by the EPS matrix to form hollow calcite crystals. These results suggest that chemical properties (i.e., abundance of dissociated acidic groups) primarily controlled the presence/absence of CaCO3 nucleation around cyanobacteria, while a physical property (i.e., submicron-scale structure of negatively charged substances) primarily controlled the numbers of crystal nuclei provided and stabilized ACC precursors as well as the calcification styles (sheath encrustation or impregnation).Shlimon, A.G., Mansurbeg, H., Othman, R.S., Gittel, A., Aitken, C.M., Head, I.M., Finster, K.W., Kjeldsen, K.U., 2020. Microbial community composition in crude oils and asphalts from the Kurdistan region of Iraq. Geomicrobiology Journal 37, 635-652. identify hydrocarbon-degrading microorganisms contributing to the formation of heavy oil we investigated the microbial community composition in different types of crude oils from oil-production facilities and in crude oil and asphalt from different natural seeps from the Kurdistan Region of Iraq (KRI). Crude oils from five out of six production facilities did not contain microorganisms detectable by 16S rRNA gene PCR amplicon sequencing likely reflecting a low microbial abundance in these samples. Crude oil and asphalt from the natural seeps hosted diverse microbial communities. The same phylotypes of uncultivated Deferribacteres and Thermodesulfobacteraceae were predominant community members across crude oils and asphalts from separate geographical locations. Soils surrounding seeps did not contain these phylotypes suggesting that they originate from the subsurface and although they seem commonly detected in hydrocarbon-rich environments their role in hydrocarbon-degradation is unknown. GC-MS analyses showed that mainly aromatic hydrocarbons were present in the crude oil and asphalt and that they were undergoing biodegradation - likely with sulfate and nitrate as terminal oxidants. In agreement, only bssA gene, but not assA gene-carrying microorganisms were detectable in the analyzed sampled. Overall our study identified several abundant uncultivated taxa with likely roles in transformation of nitrate, sulfate and hydrocarbons.Shu, S., Jain, A.K., Kheshgi, H.S., 2020. Investigating wetland and nonwetland soil methane emissions and sinks across the contiguous United States using a land surface model. Global Biogeochemical Cycles 34, e2019GB006251. estimated the distribution of CH4 emissions and sinks from wetlands (including freshwater and coastal wetlands) and nonwetland (including wet and dry soils) with a newly developed vertically resolved soil CH4 model, integrated into a global land surface model (ISAM). We calibrated and tested this integrated model with CH4 observations at test sites in the Contiguous United States (CONUS). ISAM is applied across the CONUS to estimate CH4 emissions and sinks given both recent past observed climate and wetland extent, and future climate and wetland extent driven by two scenarios, RCP4.5 and RCP8.5. Estimated net CH4 emissions for the 2000s are 13.8 TgCH4 yr?1, mostly from wetland soils. Estimated net emissions under RCP4.5 and RCP8.5 are 30% and 64% higher, respectively, in the 2090s than in the 2000s due to (1) higher temperature and seasonal wetland extent (driven by higher precipitation in the climate scenarios), which increase modeled methanogenic activity more than methanotrophic activity in soils and (2) altered transport in the soil column and exchange with the atmosphere by modeled transport processes (diffusion, ebullition, and aerenchyma transport). Nonwetland soils emit CH4 (1.4 TgCH4 yr?1) in some areas and take up CH4 (?2.9 TgCH4 yr?1) in other areas, resulting in a net estimated sink for the 2000s; the net nonwetland soil sink increases by 15% and 46% by the 2090s under RCP4.5 and RCP8.5, respectively, mainly due to drier soil conditions, which enhances methanotrophic activity and oxidation of CH4 diffused into soil from a future atmosphere with higher CH4 concentration.Shu, Y., Xu, S., Yang, F., Shu, Z., Peng, P., Huang, S., Zhen, H., 2020. The role of microfabric and laminae on pore structure and gas transport pathways of marine shales from Sichuan Basin, China. Geofluids 2020, 8844229. study investigated the effects of microfabric and laminae on the pore structure and gas transport pathways of the Silurian Longmaxi shales from Sichuan Basin. 23 shale samples with varied lithofacies were comprehensively investigated by mineralogy, organic geochemistry, pycnometry, and low-pressure nitrogen adsorption analysis. The fabric and laminae of these samples were identified using petrographic microscope and scanning electron microscopy. Permeabilities were measured using the nonsteady-state method on both perpendicular and parallel to bedding shales. The effective pore diameter controlling gas transport was estimated from gas slippage factors obtained in permeability measurements. These values were also compared to those calculated using the Winland equation. Siliceous shales studied are faintly laminated to nonlaminated and have larger porosity and specific surface area. Argillaceous/siliceous mixed shales are well laminated, whereas argillaceous shales contain many oriented clay flakes along the lamination. Both porosity and surface area are positively correlated with TOC content. Unlike most conventional reservoirs, there is a negative correlation between porosity and permeability values of the samples studied. Permeabilities parallel to bedding, ranging from 0.4 to 76.6?μD, are in control of the oriented clay flakes and silty microlaminae. Permeability anisotropy values of the shales vary between 1.3 and 49.8. Samples rich in oriented clay flakes and microlaminated fabric have relatively larger permeability and permeability anisotropy values. The effective transport pore diameters derived from gas slippage measurements are slightly lower than those calculated from the Winland equation. However, both methods have shown that the effective transport pore diameters of argillaceous shales (averaging 552?nm) are significantly higher than siliceous shales (averaging 198?nm), which underlines the control of microfabric, rather than porosity, on gas transport pathways of the shales studied.Sichert, A., Corzett, C.H., Schechter, M.S., Unfried, F., Markert, S., Becher, D., Fernandez-Guerra, A., Liebeke, M., Schweder, T., Polz, M.F., Hehemann, J.-H., 2020. Verrucomicrobia use hundreds of enzymes to digest the algal polysaccharide fucoidan. Nature Microbiology 5, 1026-1039. algae are important players in the global carbon cycle by fixing carbon dioxide into 1?Gt of biomass annually, yet the fate of fucoidan—their major cell wall polysaccharide—remains poorly understood. Microbial degradation of fucoidans is slower than that of other polysaccharides, suggesting that fucoidans are more recalcitrant and may sequester carbon in the ocean. This may be due to the complex, branched and highly sulfated structure of fucoidans, which also varies among species of brown algae. Here, we show that ‘Lentimonas’ sp. CC4, belonging to the Verrucomicrobia, acquired a remarkably complex machinery for the degradation of six different fucoidans. The strain accumulated 284 putative fucoidanases, including glycoside hydrolases, sulfatases and carbohydrate esterases, which are primarily located on a 0.89-megabase pair plasmid. Proteomics reveals that these enzymes assemble into substrate-specific pathways requiring about 100 enzymes per fucoidan from different species of brown algae. These enzymes depolymerize fucoidan into fucose, which is metabolized in a proteome-costly bacterial microcompartment that spatially constrains the metabolism of the toxic intermediate lactaldehyde. Marine metagenomes and microbial genomes show that Verrucomicrobia including ‘Lentimonas’ are abundant and highly specialized degraders of fucoidans and other complex polysaccharides. Overall, the complexity of the pathways underscores why fucoidans are probably recalcitrant and more slowly degraded, since only highly specialized organisms can effectively degrade them in the ocean.Sihi, D., Xu, X., Ortiz, M.S., O'Connell, C.S., Silver, W.L., López-Lloreda, C., Brenner, J.M., Quinn, R.K., Phillips, J.R., Newman, B.D., Mayes, M.A., 2020. Representing methane emissions from wet tropical forest soils using microbial functional groups constrained by soil diffusivity. Biogeosciences Discussions 2020, 1-28. ecosystems contribute significantly to global emissions of methane (CH4) and landscape topography influences the rate of CH4 emissions from wet tropical forest soils. However, extreme events such as drought can alter normal topographic patterns of emissions. Here we explain the dynamics of CH4 emissions during normal and drought conditions across a catena in the Luquillo Experimental Forest, Puerto Rico. Valley soils served as the major source of CH4 emissions in a normal precipitation year (2016), but drought recovery in 2015 resulted in dramatic pulses in CH4 emissions from all topographic positions. Geochemical parameters including dissolved organic carbon (C) (ridge???slope???valley), acetate (ridge?≥?slope?>?valley), and soil pH (valley???slope???ridge), and meteorological parameters like soil moisture (valley?>?slope?=?ridge) and oxygen (O2) concentrations (slope?=?ridge?>?valley) varied across the catena. During the drought, soil moisture decreased in the slope and ridge and O2 concentrations increased in the valley. We simulated the dynamics of CH4 emissions with the Microbial Model for Methane Dynamics-Dual Arrhenius and Michaelis Menten (M3D-DAMM) which couples a microbial functional group CH4 model with a diffusivity module for solute and gas transport within soil microsites. Contrasting patterns of soil moisture, O2, acetate, and associated changes in soil pH with topography regulated simulated CH4 emissions, but emissions were also altered by rate-limited diffusion in soil microsites. Changes in simulated available substrate for CH4 production (acetate, CO2, and H2) and oxidation (O2 and CH4) increased the predicted biomass of methanotrophs during the drought event and methanogens during drought recovery, which in turn affected net emissions of CH4. A variance-based sensitivity analysis suggested that parameters related to acetotrophic methanogenesis and methanotrophy were most critical to simulate net CH4 emissions. This study enhanced the predictive capability for CH4 emissions associated with complex topography and drought in wet tropical forest soils.Silva, R.C., Yim, C., Radovi?, J.R., Brown, M., Weerawardhena, P., Huang, H., Snowdon, L.R., Oldenburg, T.B.P., Larter, S.R., 2020. Mechanistic insights into sulfur rich oil formation, relevant to geological carbon storage routes. A study using (+) APPI FTICR-MS analysis. Organic Geochemistry 147, 104067. incorporation into sedimentary organic matter has a key role in carbon preservation in the geosphere. Such processes can inform strategies for human timescale carbon storage to mitigate climate change impacts and thus more detailed knowledge of sulfur incorporation into biomass species is needed. Until recently, detailed chemical characterization of sulfurized organic matter was only possible by analyzing individual building blocks obtained after desulfurization reactions. In this study, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), with atmospheric pressure photoionization in positive ion mode, (+) APPI, was used to investigate the chemical composition of sulfur rich crude oils and to obtain mechanistic insights into the sulfur incorporation reactions happening during early diagenesis. Contrary to expectations, (+) APPI FTICR-MS data show that sulfurized lipids (with up to 6 sulfur atoms and up to m/z 1100) occur as free molecules in these oils, rather than within a macromolecular network linked by (poly)sulfide bridges. In contrast to the mature Peace River (Canada) oils, the thermally immature Rozel Point (USA) and Jianghan Basin (China) oils show a carbon number preference in sulfurized species resembling biogenic precursor molecules, which highlights the importance of S-bound molecules as geochemical proxies for early diagenetic processes. This study indicates that sulfur incorporation reactions involve the formation of S-cyclic structures in which the double bond equivalent is ≥ the number of S atoms. Collision induced dissociation (CID-) FTICR-MS experiments suggest the occurrence of intermolecular sulfur incorporation reactions, but only as a mechanism that is secondary to intramolecular sulfur addition. The CID-FTICR-MS experiments indicated that steroid sulfurization typically yields S-bearing cyclic structures and that thiol/thioether groups may be present throughout the chemical matrix but only to a minor extent. In addition, CID-FTICR-MS also confirms the occurrence of sulfurized alkenones in low maturity oils. Knowledge of organic sulfur molecule formation informs routes for carbon dioxide removal technologies that could be used to sequester carbon in the geosphere and/or hydrosphere in the form of recalcitrant organic species.Simionesie, D., O’Callaghan, G., Costa, J.L.L.F.S., Giusti, L., Kerr, W.J., Sefcik, J., Mulheran, P.A., Zhang, Z.J., 2020. Clustering behaviour of polyaromatic compounds mimicking natural asphaltenes. Colloids and Surfaces A: Physicochemical and Engineering Aspects 603, 125221. behaviour of hexa-tert-butylhexa-peri-hexabenzocoronene (HTBHBC) and its derivatives has been used as a model system to mimic that of natural asphaltenes. We used light scattering and 1H-NMR spectroscopy, complemented by molecular dynamics simulation, to examine HTBHBC and its derivatives in toluene and toluene/heptane mixture, over a range of concentrations. The dispersibility of HTBHBC in toluene was found to be strongly dependent on its concentration. At concentrations below 5?mg/mL, HTBHBC appears to be fully dispersed and clustering equilibrium was reached within minutes as shown by scattering intensity measurements. At greater concentrations, the scattering intensity was approximately similar for all concentrations initially, but then decreased very slowly towards an apparent clustering equilibrium within two weeks. The mean hydrodynamic diameter of clusters, measured by dynamic light scattering, was initially around 1?μm for all concentrations greater than 5?mg/mL and then gradually reduced to around 0.4?μm at clustering equilibrium. At concentrations of 10?mg/mL and above, solid deposits were observed in toluene solutions when equilibrium was reached. 1H-NMR spectroscopy showed that the precipitate was high purity HTBHBC possessing a planar structure, while the liquid phase contained a mixture of planar HTBHBC and its non-planar derivatives, forming colloidal clusters. The results show that the clustering process of asphaltene mimics in toluene can be extremely slow and great care should be taken when preparing equilibrated solutions. We also showed that observations of the solid-liquid equilibrium and clustering behaviour can be strongly dependent on the molecular structure of the polyaromatic compounds found in natural asphaltenes, and the structural and compositional evolution of colloidal clusters following an initial dispersion of asphaltene mimics in solvents.Simpson, S.L., Osinski, G.R., Longstaffe, F.J., Schmieder, M., Kring, D.A., 2020. Hydrothermal alteration associated with the Chicxulub impact crater upper peak-ring breccias. Earth and Planetary Science Letters 547, 116425. 66 Ma, ～180 km Chicxulub impact structure in the northern Yucatán peninsula and southern Gulf of Mexico is the best-preserved large impact crater on Earth with a well-developed peak ring. The most recent drilling campaign took place offshore during the joint International Ocean Discovery Program – International Continental Scientific Drilling Program (IODP–ICDP) Expedition 364 at site M0077A (21.45°N, 89.95°W) and recovered ～830 m of continuous core. Initial examination revealed that the peak-ring comprises four main lithological units (from the base upwards): crystalline basement granitoid rocks (Unit 4); a thin layer of impact melt rocks (Units 3A and B); melt-bearing breccias (Units 2A–C); and post-impact sedimentary rocks (Unit 1). Preliminary analysis of the drill core indicated that hydrothermal alteration has affected all lithologies and is especially pervasive in the melt-bearing breccias of Unit 2 (721.6 to 617.33 meters below sea floor, mbsf). Here we present the first detailed investigation of hydrothermal alteration within the melt-bearing breccias. Alteration phases are predominantly Fe-Mg clay minerals, zeolites, alkali feldspars, calcite and minor sulfides, sulfates, opal and Fe-Ti oxides. Alteration is especially intense proximal to lithologic contacts, particularly at the base of subunit 2B where there is an abrupt increase in host rock porosity ～30 m above the impact melt rocks. The pervasiveness of clay minerals and zeolites is attributed to the high amounts of devitrified silicate glass throughout Unit 2. The phases preserved here are consistent with the findings of previous hydrothermal studies in other areas of the Chicxulub structure, and suggest an evolving water-rock system that was alkaline-saline, comparable to seawater-volcanic glass alteration.Singh, R.R., Chao, A., Phillips, K.A., Xia, X.R., Shea, D., Sobus, J.R., Schymanski, E.L., Ulrich, E.M., 2020. Expanded coverage of non-targeted LC-HRMS using atmospheric pressure chemical ionization: a case study with ENTACT mixtures. Analytical and Bioanalytical Chemistry 412, 4931-4939. analysis (NTA) is a rapidly evolving analytical technique with numerous opportunities to improve and expand instrumental and data analysis methods. In this work, NTA was performed on eight synthetic mixtures containing 1264 unique chemical substances from the U.S. Environmental Protection Agency’s Non-Targeted Analysis Collaborative Trial (ENTACT). These mixtures were analyzed by atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) using both positive and negative polarities for a total of four modes. Out of the 1264 ENTACT chemical substances, 1116 were detected in at least one ionization mode, 185 chemicals were detected using all four ionization modes, whereas 148 were not detected. Forty-four chemicals were detected only by APCI, and 181 were detected only by ESI. Molecular descriptors and physicochemical properties were used to assess which ionization type was preferred for a given compound. One ToxPrint substructure (naphthalene group) was found to be enriched in compounds only detected using APCI, and eight ToxPrints (e.g., several alcohol moieties) were enriched in compounds only detected using ESI. Examination of physicochemical parameters for ENTACT chemicals suggests that those with higher aqueous solubility preferentially ionized by ESI?. While ESI typically detects a larger number of compounds, APCI offers chromatograms with less background, fewer co-elutions, and additional chemical space coverage, suggesting both should be considered for broader coverage in future NTA research.Sinha, U., Dindoruk, B., Soliman, M., 2020. Machine learning augmented dead oil viscosity model for all oil types. Journal of Petroleum Science and Engineering 195, 107603. oil viscosity is one of the most unreliable properties to predict with classical black oil correlations. This results mostly from the large effect that oil type has on viscosity. Two dead oil samples with identical APIs (), () and can have even an order of magnitude difference in viscosity at the same temperature (Dindoruk and Christman, 2004). In this work, we tried to limit this spread to a certain degree by incorporating a parameter such as MW to capture additional information for the character of the oil. Limitations of the classical black oil correlations became even more prominent when a wide spectrum of viscosity values coupled with a wide range of temperatures are considered. Given the constraints of limited input variables, the problem becomes particularly challenging for heavy-extra heavy oils with high asphaltene content (Sinha et al., 2019), where prediction errors could easily be as high as a couple of log-cycles. Even though there are several viscosity correlations available in the industry (Ali, 2003)- (Bergman and Sutton, 2009), (De Ghetto and Villa, 1994), (Dindoruk and Christman, 2004), (Mehrotra, 1992), (Motahhari et al., 2013), (Naseri et al., 2005), (Lindeloff et al., 2003), (Lohrenz et al., 1964), (Pedersen and Fredenslund, 1987) (Petrosky and Farshad, 1995), (Peng and Robinson, 1976), (Standing, 1977), (Teja and Rice, 1981), (Yarranton et al., 2013) most of those correlations are only applicable to the oil samples belonging to specific geographical regions and/or for structurally similar oils, because of the inherent bias in the training datasets used in the development of correlations. Therefore, they are predictively valid for a relatively narrower range of oils and/or viscosity. In this work, we considered a very wide range of oils (6° API to 50° API). Therefore, producing two easy to use viscosity correlations for API (), () gravities above and below 20° API that can readily predict the viscosity at any desired temperature within an extended temperature range (15 °C to 160 °C). Also, the two sets of correlations were kept compatible in a region in the vicinity of switching points (20 API and 36 cp) so that they will have a proper transition from one branch to another. While the range of fluid properties is very wide, we were able to keep the input parameters to a minimum in terms of defining the character of the fluid (molecular weight and specific gravity). We demonstrated that the proposed correlation along with the given methodology performs much better than the leading correlations with the similar input proxies published in the literature for a wide range of viscosities (0.42 cp to 860, 000 cp). The use cases for the proposed correlation can be divided into three parts: 1) Prediction of the dead oil viscosity with limited input data, 2) use of limited in-hand viscosity or reference viscosity data to generate viscosities for the conditions that are hard to perform accurate experimentation or simply not having the physical sample in hand to do additional experiments(for example, for thermal recovery processes where viscosity is needed at elevated temperatures, or to construct the lift curves and/or tables for pipeline flow at lower temperatures)) and 3) it can be used to check the consistency and the quality of the existing data. In addition to classical correlation development efforts using known but limited physical control parameters, we have also attempted to model the viscosity with various machine learning methods K-Nearest Neighbor (KNN) (Cover and Hart, 1967) and Kernel-based Support Vector Machine (KSVM)) (, 2835), (Suykens and Vandewalle, 1999) and compared the outcome to each other and as well as against the proposed correlation. Based on calculated statistical parameters and cross-plots, the proposed correlation performed better than the other leading viscosity correlations (Bergman and Sutton, 2009), (Lindeloff et al., 2003), (Lohrenz et al., 1964), (Pedersen and Fredenslund, 1987), (Pedersen et al., 1984), (Petrosky and Farshad, 1995), (Standing, 1977), (Teja and Rice, 1981), (Yarranton et al., 2013) and as well as the selected supervised machine learning regression principles (), () such as KNN and KSVM. The subject correlation also helps in improving the accuracy as well as guiding the performance of these otherwise “Blackbox” machine learning principles as it can fill the gaps in the data especially in the context of extending the tuned viscosities based on a single point measurement (reference viscosity) in temperature domain. Furthermore, we also explain how it can be combined with Sinha et al. (Sinha et al., 2019) relative viscosity correlation to include the impact of asphaltene concentration to be able to estimate vertical or areal viscosity variations which can also ultimately help to improve the mobility cut-off predictions of the asphaltene/tar mat zones or heavier fluids.Skejo, J., Franjevi?, D., 2020. Eukaryotes are a holophyletic group of polyphyletic origin. Frontiers in Microbiology 11, 1380. doi: 10.3389/fmicb.2020.01380. living beings can be assigned to one of the three domains of life (Woese et al., 1990; Williams et al., 2013), all of which are monophyletic (Doolittle, 2014). Two prokaryotic domains, Archaea and Bacteria, are characterized by the lack of intercellular compartments (Martin, 1999; McInerney et al., 2014), whereas eukaryotes, characterized by the complexity of cellular structures and life cycle, originated via symbiogenesis of an archaeal host and a bacterial endosymbiont i.e. proto-mitochondrion (Mereschkowsky, 1905; Zimorski et al., 2014; Mu?oz-Gómez et al., 2017; Roger et al., 2017). With millions of described species (Costello et al., 2013; Adl et al., 2019), eukaryotes are morphologically the most diverse of the three groups bearing symbiogenesis as the hallmark of their evolutionary origin (Wallin, 1927; Margulis, 1991). Symbiogenesis has always been a common phenomenon in the eukaryotic evolution (McFadden, 2001; Nowack and Melkonian, 2010; Bonfante and Desirò, 2017). Nevertheless, there are still many unanswered questions regarding the prokaryotes that participated in eukaryogenesis. The true evolutionary position of eukaryotes is hence the subject of continuing debates and it has still not been widely agreed if eukaryotes represent a separate domain (Williams et al., 2013; Doolittle, 2020). Alphaproteobacteria is known to be the ancestor of mitochondria (Roger et al., 2017). However, our understanding of the archaeal lineage that gave rise to the eukaryotic nuclear genome is still insufficient. Asgard archaea, which were recently identified based on metagenome-assembled sequences (Spang et al., 2015; Seitz et al., 2016; Zaremba-Niedzwiedzka et al., 2017; MacLeod et al., 2019), possess eukaryotic signature proteins (ESPs) involved in cytoskeleton regulation (Akil and Robinson, 2018; Akil et al., 2019), and are being cultivated now (Imachi et al., 2020). The first photographed member of Asgard is known under the name “Candidatus Prometheoarchaeum syntrophicum,” and it does not exhibit eukaryotic features (such as the presence of mitochondrion, nucleus, endoplasmic reticulum, or sexual reproduction), but rather exhibits typical prokaryotic features, such as small size, spherical (coccoid) body, and lack of organelles (Imachi et al., 2020). Recently, Fournier and Poole (2018) presented a taxonomic view in which Asgard represented the main eukaryotic ancestor (parent) and were, along with eukaryotes, united into a “monophyletic” group named Eukaryomorpha. The aim of this opinion manuscript is to debate this newly introduced term. We briefly review the meaning of the terms “monophyletic” and “polyphyletic,” and we draw attention to the bacterial contribution to eukaryogenesis.Paraphyletic Means MonophyleticEvolutionary biologists use the term “monophyly” in various ways (see e.g., Envall, 2008), just as Hennig (1950, 1966), the creator of the term, originally did, which has hitherto ensued a lot of confusion (Envall, 2008). In this opinion, we use the term “monophyletic” only for groups with a single definable ancestor, meaning that paraphyletic groups are also considered as monophyletic. Each taxonomic group can be characterized by either having a shared (single) ancestor—“monophyletic group” or having numerous ancestors—“polyphyletic group” (Hennig, 1950, 1966). Polyphyletic groups are not taxonomically desirable, and traditionally, characters shared by members of such a group represent homoplasies (analogies), i.e., traits that evolved independently in similar environments on account of similar selective advantages (Wake et al., 2011). A historical error occurred when Hennig (1950, 1966) defined two groups, monophyletic and paraphyletic, based on the inclusion of all descendants of a given ancestor. If all the descendants of a given ancestor belonged to one group, it was regarded as a monophyletic group, and if this was not the case, it was regarded as a paraphyletic group (Hennig, 1950, 1966). Missing from such definition was the distinction between a group with a single ancestor and a group that includes all the descendants of an ancestor, which were both defined as monophyletic by Hennig (1950, 1966). Ashlock (1971, 1972, 1974, 1979) noticed the erratum and introduced the term “holophyletic group,” referring to a monophyletic group that includes all the descendants of an ancestor. Therefore, a “paraphyletic group” is a monophyletic one that does not include all the descendants of an ancestor (Figures 1A–C).Well-known examples of holophyletic groups are mammals (descendants of Therapsida), snakes (descendants of earless and legless lizards), birds (descendants of Dinosauria), modern amphibians, tetrapods (land vertebrates, descendants of fish), jawed vertebrates, bilaterians (bilaterally symmetric animals), animals, and eukaryotes (Pough et al., 1999; Nielsen, 2012; Doolittle, 2014). Examples of paraphyletic groups are reptiles or amniotes (whose descendants are mammals and birds), amphibians (a group including Lissamphibia and extinct amphibians whose descendants are reptiles), sarcopterygians (whose descendants are tetrapods), fish (Pisces) (as they include all vertebrates excluding those inhabiting land), jawless fish (lampreys, hagfish, and extinct groups related to them, whose descendants are also jawed fish), bryophytes in wider sense (as land plants are their descendants), streptophytes (stonewort and relatives, if plants are excluded), archaeplastids (as secondary plastids of SAR and euglenoids are not considered to be archaeplastid members anymore), cyanobacteria (because plastids are regarded as organelles, not cyanobacteria anymore), prokaryotes (because eukaryotes are excluded), Archaea (because the nucleus is not regarded to be an archeon anymore), and Bacteria (because mitochondria are not regarded as Alphaproteobacteria anymore; Pough et al., 1999; Nielsen, 2012; Doolittle, 2014).If we ignore the presence of mitochondria and existence of lateral gene transfer from bacteria to the eukaryotic host, the origin of the eukaryotic nucleus could be compared to the origin of mammals and birds within amniotes, as described in Fournier and Poole (2018). However, the origin of eukaryotes is not comparable to the origin of these groups, and the bacterial contribution to eukaryogenesis should not be neglected. Eukaryotes are of polyphyletic origin, as their ancestor, LECA, sits on both branches of life—the archaeal (Asgard) and the bacterial branch (Alphaproteobacteria).Polyphyletic, Reticulated Events in EvolutionWell-established examples of natural polyphyletic events include lateral gene transfer (LGT) in prokaryotes (Nelson-Sathi et al., 2015), symbiogenesis in prokaryotes and eukaryotes (biofilms, endosymbiosis, ectosymbiosis, etc.; e.g., Vogels et al., 1980; López et al., 2010; Naumann et al., 2010), and sexual reproduction in eukaryotes (Speijer et al., 2015). Genes can also be of polyphyletic origin; those genes are known as chimeric genes (e.g., Méheust et al., 2018). Polyphyletic origin is an evolutionary event in which two lineages (individuals, populations, or species) merge into a single, “chimeric” lineage. A lineage of polyphyletic origin should not be united with any of its ancestors in an attempt to form a higher monophyletic group, as it will not result in such. Even though eukaryotes are a monophyletic and holophyletic group by definition, they are of polyphyletic origin because of the very nature of their ancestor's, LECA's origin. Today, the polyphyletic origin of eukaryotes is a well-supported scientific theory. Eukaryotic (syn)apomorphies are the traits of eukaryotic complexity: nuclei, mitochondria, Golgi apparatus, endoplasmic reticulum, and sexual reproduction (Koonin, 2010; Koumandou et al., 2013; Garg and Martin, 2016; Doolittle, 2020).Eukaryogenesis is not a unique example of polyphyletic origin of a monophyletic group. Other such events are widely dispersed in the tree of life. Known examples are hybrid species, which originated via hybridization of two species, usually (but not always) from the same genus (Seehausen, 2004; Grant and Grant, 2008; Meier et al., 2017). Homo sapiens is an example of such species. It is a hybrid between H. heidelbergensis, H. neanderthalensis, and Denisovians (Sankararaman et al., 2016). The Jutland bow-winged grasshopper (Chorthippus jutlandica) is a unique species which originated from the hybridization of C. brunneus and C. biguttulus in Denmark (Gottsberger, 2007). Domestic wheat is a hybrid between species belonging to the genera Triticum and Aegilops (Ozkan et al., 2001). There are even examples of one of the ancestral species being extinct, but its mitochondrial genome still being present, which is called a ghost lineage (Recuero et al., 2014). There is no example of a natural monophyletic group that could be composed of any of the aforementioned species and one of its parents, as is the case with Eukaryotes, Asgard, and Eukaryomorpha.Lichens not only gave rise to the concept of symbiosis (de Bary, 1879), but they are also the classical example of organisms that originated by symbiogenesis (Lutzoni and Miadlikowska, 2009). Lichen species are composed of mycobionts (Ascomycota and/or Basidiomycota) and photobionts (Chlorophyta or Cyanobacteria; Lutzoni and Miadlikowska, 2009; Spribille et al., 2016; Tuovinen et al., 2019). Symbiosis is species-specific (Lindsay, 1856), co-dependent, and the symbionts usually cannot survive outside the lichen. Lichens are an example of a polyphyletic group with multiple polyphyletic origins. Relatives of lichen-forming green algae (symbiont lineages) should not be designated as “Lichenomorpha,” even though they represent one of the constituent evolutionary lineages that gave rise to lichens. Cyanobacteria should not be designated as “Plastidomorpha,” despite the fact that this group contains the ancestors of plastids. The case of Archaeplastida (primary photosynthetic eukaryotes) is an interesting one and should be addressed in a separate essay. The supergroup originated via plastidogenesis, an anastomosis between cyanobacteria and eukaryotes; and has since contributed to many anastomoses (secondary endosymbioses) in the eukaryotic tree (McFadden, 2001). The origin of the plastid may be comparable to the origin of mitochondria, however probably only to a certain extent, because of the complexity of the archaeplastidian eukaryotic parent.Bacterial Contribution to Eukaryogenesis Should not be NeglectedBacteria (mainly Alphaproteobacteria, but others as well) are as important as Archaea in eukaryogenesis. Mitochondria are of alphaproteobacterial origin, nuclei of chimeric (archaeal and bacterial), and plastids of cyanobacterial origin. The strongest signals in eukaryotic genomes are, indeed, proteobacterial, archaeal, and cyanobacterial (Pisani et al., 2007; Ku et al., 2015). Because of the combination of archaeal and bacterial features exhibited by eukaryotes, they should not be assigned to a higher taxon along with any of their ancestors.Eukaryotes exhibit a unique mixture of prokaryotic features, most of which can be traced back to either Archaea or Bacteria. Unlike prokaryotes, eukaryotes do not exchange genes via LGT, but by sexual reproduction (Ku et al., 2015). An archaeon is known to have been the host of the eukaryote-forming endosymbiosis, contributing genetic machinery and ribosomal DNA (Esser et al., 2004; Thiergart et al., 2012; Gould et al., 2016). There is an interesting hypothesis stating that eukaryotic membranes originated from bacterial vesicle secretion (Gould et al., 2016). The genes encoded in the nucleus are as bacterial as they are archaeal. A larger part of the eukaryotic genome has bacterial homologs (Esser et al., 2004; Brueckner and Martin, 2020) that most likely originated from the EGT (endosymbiotic gene transfer) with the proto-mitochondrion ancestor (Brueckner and Martin, 2020), whereas archaeal genes are less numerous in eukaryotic genome, but also important (Pisani et al., 2007; Brueckner and Martin, 2020). The origin of mitochondrion was a prerequisite for the existence of sexual reproduction and meiosis. These processes required large amounts of energy (ATP), and no known prokaryotic cell is able to produce such amount of ATP (Garg and Martin, 2016). Some authors still dispute the uniqueness of eukaryogenesis and the importance of mitochondria in the definition of eukaryotes (e.g., Booth and Doolittle, 2015; Lynch and Marinov, 2016).We think that the bacterial contribution to eukaryogenesis should not be neglected in view of the facts that: (1) mitochondria, whose presence is a eukaryotic synapomorphy, represents the true descendant of Alphaproteobacteria, (2) most of the eukaryotic nuclear DNA originated via gene transfer from bacteria, and (3) all eukaryotic membranes may be of bacterial origin.Concluding ThoughtsBecause of the polyphyletic origin of the eukaryotic monophylum, eukaryogenesis within prokaryotes is not comparable with mammal origin within paraphyletic reptiles. Both synapomorphies and plesiomorphies represent apomorphies and are indeed suitable for defining monophyletic (holophyletic and paraphyletic) groups. Alphaproteobacteria (Bacteria) and Asgard (Archaea) are the ancestors of LECA (the Last Eukaryotic Common Ancestor). The presence of ESPs in Asgard does not dispute the polyphyletic origin of eukaryotes; it only further corroborates it. “Candidatus Prometheoarchaeum syntrophicum” is the closest relative to eukaryotes and the only Asgard with available microscopy data. This newly discovered species has a prokaryotic cell organization and does not exhibit features of eukaryotic complexity (nucleus, mitochondrion, meiotic cycle), and thus, it does not belong to Eukaryomorpha.Along with Cyanobacteria, non-photosynthetic eukaryotes are the ancestors of the primary photosynthetic eukaryotes (archaeplastidians). Non-photosynthetic eukaryotes are not the ancestors of plastids, hence LECA is not the only ancestor of the extant eukaryotic diversity. Eukaryotes are monophyletic by definition, as they have a single ancestor, LECA. 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Asgard archaea illuminate the origin of eukaryotic cellular complexity. Nature 541, 353–358. doi: 10.1038/nature21031Zimorski, V., Ku, C., Martin, W. F., and Gould, S. B. (2014). Endosymbiotic theory for organelle origins. Curr. Opin. Microbiol. 22, 38–48. doi: 10.1016/j.mib.2014.09.008Skoczylas, N., Pajdak, A., Kudasik, M., Braga, L.T.P., 2020. CH4 and CO2 sorption and diffusion carried out in various temperatures on hard coal samples of various degrees of coalification. Journal of Natural Gas Science and Engineering 81, 103449. aim of the study was to analyse the effect of temperature on the sorption and diffusion of CO2 and CH4 on hard coal. Four coal samples, characterized by various degrees of coalification, were used in the research. The sorption measurements were carried out in three temperature values: 278 K, 313 K and 353 K and for the consecutive pressure values of 1 bar, 5 bar and 15 bar. Langmuir's sorption capacity in relation to CH4 and CO2 was the highest for the coal with the lowest degree of coalification and was 32.15 cm3/g and 76.4 cm3/g respectively. The lowest Langmuir sorption capacity in relation to CH4 and CO2 were obtained for medium-rank coal (19.23 cm3/g and 29.26 cm3/g) and high-rank coal (20.33 cm3/g and 32.89 cm3/g). The temperature growth resulted in a reduction of the sorption capacity of coal in relation to CH4 and CO2, and that decline was exponential in relation to temperature. The absolute decreases in the total sorption capacity were from 0.03 cm3/g to 0.21 cm3/g in relation to CH4, and from 0.10 cm3/g to 0.51 cm3/g in relation to CO2, per 1 K temperature increase. Within the measurement temperature range of 278–353 K, no ?critical temperature point”, above which there is no reduction in CH4 and CO2 sorption, was observed. An increase in the temperature pushed up the values of the effective diffusion coefficients, in relation to CH4 by more than one order of magnitude, and in relation to CO2 by approximately four times. A decrease in the selectivity of CO2/CH4 was also observed along with the coal rank. The ratio of effective diffusion coefficient values DeCO2/DeCH4 for all the investigated coal samples declined strongly along with temperature growth.Skvortsov, V.A., 2020. Assessment of the oil and gas potential of the basement of the southern part of the Siberian Platform and deep-seated oil exploration. Doklady Earth Sciences 492, 302-305. main goal is to assess the oil and gas potential of the basement of the southern part of the Siberian Platform as an additional source for the long-term filling of the East Siberia–Pacific Ocean pipeline with hydrocarbons. The initial reserves in the fields, which were discovered in the sedimentary cover on the Siberian Platform, are far below the reserves of the fields of Western Siberia and the Volga Region, where the drilling of deep wells showed the connection of reserves with the basement; the reserves are renewed in a natural way. On the Siberian Platform, the drilling usually ended at the “cover–basement” boundary (at the most productive level). In the wells, there are the following signs that indicate the oil and gas potential of the basement: “black” zircons in granitoids containing radioactive elements, multi-layered oil reservoirs, which are associated with deep faults, and mantle fluids bearing hydrogen and liquid hydrocarbons. Based on the signs listed, which indicate the promising basement rocks, it is necessary to change the existing methods for prospecting and evaluating oil in the sedimentary cover and to focus on the exploration of heavy deep oil in the basement rocks.Smrzka, D., Feng, D., Himmler, T., Zwicker, J., Hu, Y., Monien, P., Tribovillard, N., Chen, D., Peckmann, J., 2020. Trace elements in methane-seep carbonates: Potentials, limitations, and perspectives. Earth-Science Reviews 208, 103263. authigenic carbonates form shallow-water microbialites, mud mounds, and hydrocarbon-seep deposits and contain appreciable amounts of trace elements that yield information on paleoenvironments. Element patterns of some of these carbonates archive metabolic processes through geologic time since many trace elements are redox-sensitive and participate in biological cycling. Trace element distributions in microbial carbonates not only yield information on the redox state of ancient oceans, but also on the chemical evolution of Earth’s hydrosphere and atmosphere. Trace element patterns can be used to distinguish marine from freshwater sources, to estimate water depth, and can help identify microbial metabolisms through time. A major issue concerning the use of marine carbonates as a paleoenvironmental archive is assessing the degree of early and late diagenetic alteration, which can modify or even reset the original content and distribution of trace elements. The degree and effect of early and late diagenetic alteration can be evaluated by comparing element contents to organic and other inorganic geochemical proxies. Authigenic hydrocarbon-seep carbonates forming in seafloor sediments are the product of microbial oxidation of methane and other hydrocarbon compounds. Seep carbonates are excellent archives, whose trace element contents yield information on sedimentary redox processes, as well as information on seepage intensity and fluid composition. Trace elements serve as proxies in these highly dynamic environments shaped by fluid seepage and chemosynthesis, and can help to reconstruct the evolution of chemosynthesis-based life at seeps through the Phanerozoic.Soares, J.L., Nogueira, A.C.R., dos Santos, R.F., Sansjofre, P., Ader, M., Truckenbrodt, W., 2020. Microfacies, diagenesis and hydrocarbon potential of the Neoproterozoic cap carbonate of the southern Amazon Craton. Sedimentary Geology 406, 105720. low-latitude Marinoan glaciation (635?Ma) record in the southern Amazon Craton has been one of the most important sites with strong evidence for the Neoproterozoic Snowball Earth hypothesis. In Central Brazil, the 50-m-thick carbonate succession of the post-Marinoan cap carbonate exposed in the Tangará da Serra region, Central Brazil, represents a complementary section of the classical occurrence of the Puga cap carbonate in Mirassol d'Oeste region, that overlies glaciogenic deposits marking the well-preserved Cryogenian-Ediacaran boundary in South America. The 8-m-thick cap dolostone that represents the Mirassol d'Oeste Formation consists of pinkish microcrystalline peloidal dolomudstone, exhibiting even parallel to low-angle lamination locally tubestone, and megaripple bedded dolopackstone. The cap dolostone is succeeded upsection by the cap cementstone limestone (basal Guia Formation), comprising laminated lime mudstone rich in silt-sized terrigenous grains (quartz), and subordinately bituminous shale, dolomitic marls, intraformational breccias, and abundant calcite crystal fans and crusts. Crystal fans occur in isolated and decimetre-scale arrays and are considered aragonite pseudomorphs. Primary precipitation of dolomite, crystal fans, and micrite and the formation of tubestone are related to depositional processes. The cap dolostone was affected by the neomorphism of the dolomicrite, development of vug and intercrystalline porosity, euhedral dolomite precipitation, synsedimentary fracturing, calcite and quartz precipitation, chemical compaction, Fe-oxide substitution, and precipitation. The diagenetic processes of the cap cementstone limestone were pyrite precipitation, calcite cementation, neomorphism of micrite and crystal fan, partial crystal fan dissolution, dolomitization, chemical compaction, fracturing, ferrous dolomite and calcite precipitation, pyrite (pseudomorph) and micrite replacement with Fe-oxide and replacement of rhombohedral dolomite by Mn-oxides. Hydrocarbons are rare and its migration represents the last diagenetic event being found: 1) in fractures and interpeloidal, vug and intercrystalline pores (~2%) with low permeability and connectivity of the cap dolostone; and 2) in intercrystalline pores, fractures, and rare pores in crystal fans of the cap cementstone limestone.During the post-Marinoan sea-level rise occurred the establishment of a shallow to moderately deep microbially induced dolomitic platform locally influenced by storm-action. The progressive transgression led the implantation of a deep anoxic and CaCO3-oversaturated aragonitic platform. The similarities of cap carbonate microfacies among the post-Marinoan succession worldwide reflects an extraordinary and non-recurring global precipitation event in geological history. In contrast, besides the majority of cap carbonate have the same textural and compositional framework, the diagenetic history seems to be regional and completely dependent on the tectonic, thermal, and burial history of the depositional basins where they were deposited.Sobreira, T.J.P., Avramova, L., Szilagyi, B., Logsdon, D.L., Loren, B.P., Jaman, Z., Hilger, R.T., Hosler, R.S., Ferreira, C.R., Koswara, A., Thompson, D.H., Cooks, R.G., Nagy, Z.K., 2020. High-throughput screening of organic reactions in microdroplets using desorption electrospray ionization mass spectrometry (DESI-MS): hardware and software implementation. Analytical Methods 12, 3654-3669. study describes an automated system used for high throughput screening of reaction conditions based on accelerated reactions occurring in small volumes of reagents. Reaction mixtures are prepared in array format using a fluid handling robot and spotted on a flat polytetrafluoroethylene plate at densities up to 6144 per plate. The reaction and analysis steps are performed simultaneously using desorption electrospray ionization (DESI) to release microdroplets containing the reaction mixture from the plate for reaction prior to arrival at a mass spectrometer. Analysis rates are up to 1 reaction mixture per second and data are recorded in real time using an ion trap mass spectrometer. Beacon compounds are used to triangulate position on the plate and this allows tandem mass spectrometry (MS/MS) to be performed on confirm products of interest. Custom software allows the user to control the system. It is also used to receive data from the DESI mass spectrometer to screen the spectra for compounds of interest, to perform MS/MS and to save data. This custom software also communicates with the software controlling the fluid handling robot (Biomek i7) as well as the Beckman software used to prepare reaction mixtures and also the software that controls the solvent used as the DESI spray. Data were recorded for N-alkylation, N-acylation and N-sulfonylation reactions in three 8 hour experiments on successive days to establish the ruggedness and repeatability of the system. Repeatability is high (94–97%) over this period with false negative 6% (depending on noise threshold chosen). Plates containing 384 reaction mixtures are analyzed in 7 min by moving the DESI sprayer in steps under the sprayer instead of continuously.Soltwisch, J., Heijs, B., Koch, A., Vens-Cappell, S., H?hndorf, J., Dreisewerd, K., 2020. MALDI-2 on a trapped ion mobility quadrupole time-of-flight instrument for rapid mass spectrometry imaging and ion mobility separation of complex lipid profiles. Analytical Chemistry 92, 8697-8703. laser desorption/ionization combined with laser-induced postionization (MALDI-2) is a recently introduced method for enhanced mass spectrometry imaging of numerous classes of biomolecules, including phospho- and glycolipids in tissue sections at high lateral resolution. Here we describe the first adaptation of the technology to a Bruker timsTOF fleX mass spectrometer. Upon use of a 1 kHz postionization laser, MALDI-2 produces a sizable increase in the number of detected features as well as in ion signal intensities. This enhancement is similar to that described previously for low repetition rate MALDI-2 systems, but now enables substantially enhanced measurement speeds. In our proof-of-concept study, we furthermore demonstrate, on examples of rat brain and testis tissue sections, that the combination of MALDI-2 with the trapped ion mobility spectrometry (TIMS) functionality of the instrument can crucially support unravelling the complex molecular composition of the lipidome. Numerous isomeric/isobaric ion species are successfully separated upon using the collisional cross section (CCS) as additional specific physical property. With the possibilities of high data acquisition speed or high separation powers in combination with the increased sensitivity of MALDI-2 available in one instrument, the described methodology could be a valuable tool in many areas of biological and medical research.Son, S., Kim, S., Yim, Y.-H., Kim, S., 2020. Reproducibility of crude oil spectra obtained with ultrahigh resolution mass spectrometry. Analytical Chemistry 94, 9465-9471. this study, the reproducibility of crude oil analyzed with (+) atmospheric pressure photoionization ultrahigh resolution mass spectrometry was evaluated. Three sets of data were obtained at intervals of approximately a month for a span of three months. For each monthly data set, four oil samples were analyzed with four replicates in 1 day. The obtained 48 spectra were processed to examine the reproducibility of the class, double bond equivalent (DBE), and individual peak distributions. The reproducibility of the relative abundance was better than that of the absolute abundance. The distributions of major classes were consistent within the three sets with a less than 1% relative standard deviation (RSD). The DBE distribution for each data set was reproducible within 1% RSD, whereas the DBE distributions for the combined data sets had RSD values of 1%–6%. The RSD values were higher for minor components, suggesting that care must be taken in the use of minor values for quantitative or semiquantitative evaluation. The relative abundances of individual peaks in the major classes were reproducible within 1%–3% RSD for each data set. However, the RSD values of the combined data sets were over 10%, even for abundant peaks. The smaller RSD of the class and DBE distributions than that of individual peaks for combined data sets strongly suggest that variations observed from individuals were caused by random errors. The data presented in this study provide guidelines for evaluating petroleomic data obtained in the laboratory at different times or laboratories.Song, C., Elsworth, D., 2020. Microbially induced calcium carbonate plugging for enhanced oil recovery. Geofluids 2020, 5921789. high-permeability zones within oil reservoirs is a straightforward approach to enhance oil recovery by diverting waterflooding fluids through the lower-permeability oil-saturated zones and thereby increase hydrocarbon displacement by improvements in sweep efficiency. Sporosarcina pasteurii (ATCC 11859) is a nitrogen-circulating bacterium capable of precipitating calcium carbonate given a calcium ion source and urea. This microbially induced carbonate precipitation (MICP) is able to infill the pore spaces of the porous medium and thus can act as a potential microbial plugging agent for enhancing sweep efficiency. The following explores the microscopic characteristics of MICP-plugging and its effectiveness in permeability reduction. We fabricate artificial rock cores composed of Ottawa sand with three separate grain-size fractions which represent large (40/60 mesh sand), intermediate (60/80 mesh sand), and small (80/120 mesh sand) pore sizes. The results indicate a significant reduction in permeability after only short periods of MICP treatment. Specifically, after eight cycles of microbial treatment (about four days), the permeability for the artificial cores representing large, intermediate, and small pore size maximally drop to 47%, 32%, and 16% of individual initial permeabilities. X-ray diffraction (XRD) indicates that most of the generated calcium carbonate crystals occur as vaterite with only a small amount of calcite. Imaging by SEM indicates that the pore wall is coated by a calcium carbonate film with crystals of vaterite and calcite scattered on the pore wall and acting to effectively plug the pore space. The distribution pattern and morphology of microbially mediated CaCO3 indicate that MICP has a higher efficiency in plugging pores compared with extracellular polymeric substances (EPSs) which are currently the primary microbial plugging agent used to enhance sweep efficiency.Song, H., Huang, S., Jia, E., Dai, X., Wignall, P.B., Dunhill, A.M., 2020. Flat latitudinal diversity gradient caused by the Permian–Triassic mass extinction. Proceedings of the National Academy of Sciences 117, 17578-17583.: The deep-time dynamics of the latitudinal diversity gradient (LDG), especially through dramatic events like mass extinctions, can provide invaluable insights into the biotic responses to global changes, yet they remain largely underexplored. Our study shows that the shape of marine LDGs changed substantially and rapidly during the Permian–Triassic mass extinction from a modern-like steep LDG to a flat LDG. The flat LDG lasted for ～5 My and was likely a consequence of the extreme global environment, including extreme warming and ocean anoxia, which ensured harsh conditions prevailing from the tropics to the poles. Our findings highlight the fundamental role of environmental variations in concert with severe biodiversity loss in shaping the first-order biogeographic patterns.Abstract: The latitudinal diversity gradient (LDG) is recognized as one of the most pervasive, global patterns of present-day biodiversity. However, the controlling mechanisms have proved difficult to identify because many potential drivers covary in space. The geological record presents a unique opportunity for understanding the mechanisms which drive the LDG by providing a direct window to deep-time biogeographic dynamics. Here we used a comprehensive database containing 52,318 occurrences of marine fossils to show that the shape of the LDG changed greatly during the Permian–Triassic mass extinction from showing a significant tropical peak to a flattened LDG. The flat LDG lasted for the entire Early Triassic (～5 My) before reverting to a modern-like shape in the Middle Triassic. The environmental extremes that prevailed globally, especially the dramatic warming, likely induced selective extinction in low latitudes and accumulation of diversity in high latitudes through origination and poleward migration, which combined together account for the flat LDG of the Early Triassic.Song, Y., Feng, C., Wang, Z., Sun, Z., 2020. Estimation of oil saturation via pseudo capillary pressure curve from nuclear magnetic resonance log data in tight conglomerate reservoirs. Arabian Journal of Geosciences 13, 575. conglomerate reservoirs have complex pore structure and strong heterogeneity which could bring great difficulties in the identification of oil and water layers. In order to solve this problem, the tight conglomerate reservoirs of Triassic Baikouquan Formation and Permian Urho Formation in Mahu Depression, Northwest Junggar Basin in China are selected as the study area. Firstly, 23 representative core plunger samples were selected from 9 wells. The experimental data of helium porosity, permeability, mercury intrusion capillary pressure (MICP) curve, and nuclear magnetic resonance (NMR) T2 spectrum under completely watered condition were measured and analyzed. Secondly, conglomerate reservoir classification criterion was built based on flow zone indicator (FZI). Its classification results conform to the classification of J function and core images. Thirdly, the piecewise power function was adopted to predict the pseudo capillary pressure curve by NMR T2 spectrum and the corresponding models were established via reservoir classification. Fourthly, based on the obtained pseudo capillary pressure curve and average J function curve, a novel method for predicting oil saturation by the ratio of median radius was proposed. Finally, the built models were used to process the experimental data not involved in modeling and log data. The predicting results are well consistent with the experimental results, which indicates the high reliability of the models. The established models are essential for helping the classification of tight conglomerate reservoirs, calculation of reservoir parameters, and identification of oil and water layers.Sorci, A., Cirilli, S., Clayton, G., Corrado, S., Hints, O., Goodhue, R., Schito, A., Spina, A., 2020. Palynomorph optical analyses for thermal maturity assessment of Upper Ordovician (Katian-Hirnantian) rocks from Southern Estonia. Marine and Petroleum Geology 120, 104574. of integrated, multi-proxy optical analytical techniques for the assessment of thermal maturity of organic matter was tested in Katian to Hirnantian (Upper Ordovician) sediments from a subsurface succession in southern Estonia. The investigated Valga-10 drill core section consists of a biostratigraphically well-constrained succession deposited in the outer part of a carbonate shelf (Livonian basin). The diverse and well-preserved palynological assemblages permitted the analysis of thermally-induced modifications of optical properties of small and large acanthomorph acritarchs. Qualitative methods such as UV-fluorescence and Acritarch Alteration Index (AAI) were calibrated against the quantitative Palynomorph Darkness Index (PDI). The occurrence of vitrinite-like organoclasts allowed reflectance measurements in some of the investigated samples. The strong fluorescence and pale to yellow colour of acritarchs, combined with low PDI and organoclast reflectance values, suggest thermally immature kerogen and a limited burial diagenesis in the study area. Moreover, PDI showed a good correlation with UV-fluorescence, allowing a calibration of these two techniques and proving the reliability of PDI for thermal maturity estimation in sedimentary rocks unsuitable for Rock-eval pyrolysis and vitrinite reflectance. Furthermore, the applied methodologies, permitted the differentiation of reworked from in situ organic matter and highlighted the potential of the former for sequence stratigraphic investigations.Sorokhtin, N.O., Lobkovsky, L.I., Kozlov, N.E., 2020. The crust–mantle carbon cycle and origin of abiogenic hydrocarbons. Oceanology 60, 248-258. paper studies carbon transformation and transfer processes in the crust and mantle. Sediments dragged into subduction zones are dewatered, broken down, and altered by metamorphic processes. Some carbon compounds are immersed in the sublithospheric mantle and transported by convective currents into the rift zones of mid-ocean ridges. There they are transformed again, forming new chemical compounds, and are carried out by hydrothermal fluids to the surface in the form of carbonates, various hydrocarbons, and carbon dioxide dissolved in the fluid. Precipitated from solutions, they are deposited on the seafloor as sediment, forming carbonate and carbon-containing structural–material complexes. As a result of the multistage physicochemical transformation mechanism in the crust–mantle regions of the Earth, carbon compounds acquire features of abiogenic (mantle) origin, although they are initially exogenic formations. The crust–mantle carbon cycle is part of the global cyclic transfer of carbon from the atmosphere to the mantle and vice versa.Spangenberg, J.E., Schweizer, M., Zufferey, V., 2020. Shifts in carbon and nitrogen stable isotope composition and epicuticular lipids in leaves reflect early water-stress in vineyards. Science of The Total Environment 739, 140343. in leaf carbon and nitrogen isotope composition (δ13C and δ15N values) and the accumulation of epicuticular lipids have been associated with plant responses to water stress. We investigated their potential use as indicators of early plant water deficit in two grapevine (Vitis vinifera L.) cultivars, Chasselas and Pinot noir, that were field-grown under well-watered and water-deficient conditions. We tested the hypothesis that the bulk δ13C and δ15N values and the concentrations of epicuticular fatty acids may change in leaves of similar age with the soil water availability. For this purpose, leaves were sampled at the same position in the canopy at different times (phenological stages) during the 2014 growing season. Bulk dry matter of young leaves from flowering to veraison had higher δ13C values, higher total nitrogen content, and lower δ15N values than old leaves. In both cultivars, δ15N values were strongly correlated with plant water deficiency, demonstrating their integration of the plant water stress response. δ13C values recorded the water deficiency only in those plants that had not received foliar organic fertilization. The soil water deficiency triggered the accumulation of C>26 fatty acids in the cuticular waxes. The compound-specific isotope analysis (CSIA) of fatty acids from old leaves showed an increase in δ13C among the C16-C22 chains, including stress signaling linoleic and linolenic acids. Our results provide evidence for leaf 13C-enrichment, 15N-depletion, and enhanced FA-chain elongation and epicuticular accumulation in the grapevine response to water stress. The leaf δ13C and δ15N values, and the concentration of epicuticular fatty acids can be used as reliable and sensitive indicators of plant water deficit even when the level of water stress is low to moderate. They could also be used, particularly the more cost-efficient δ13C and δ15N measurements, for periodic biogeochemical mapping of the plant water availability at the vineyard and regional scale.Srain, B.M., Sobarzo, M., Daneri, G., González, H.E., Testa, G., Farías, L., Schwarz, A., Pérez, N., Pantoja-Gutiérrez, S., 2020. Fermentation and anaerobic oxidation of organic carbon in the oxygen minimum zone of the upwelling ecosystem off concepción, in central Chile. Frontiers in Marine Science 7, 533. doi: 10.3389/fmars.2020.00533. studied the dynamics of fermentation and anaerobic degradation of organic matter at a fixed station in the Oxygen Minimum Zone (OMZ) within the Humboldt Current System off Concepción, central Chile. Products of the main anaerobic microbial reactions [fermentation, denitrification, and reduction of Fe(OH)3 and SO42–] were analyzed during laboratory incubations of OMZ waters. Fermentation of glucose and amino acids resulted in the production of volatile fatty acids, mainly acetate; these compounds were detected year-round in in situ water samples and were associated with high primary production rates and presence of O2-deficient waters at the sampling site. In contrast, whilst ethanol was produced from glucose fermentation by OMZ water microorganisms under laboratory conditions, it was not detected in the water column during the annual cycle. Evidence of acetate oxidation (which is thermodynamically feasible), with Fe(OH)3 as an electron acceptor, suggests that microbial activity could reduce solid-phase Fe carried by rivers using fermented metabolites in oxygen-depleted water, thus releasing dissolved bioavailable Fe. Here we present evidence for productivity-driven seasonality of biogeochemical cycles in the Humboldt system, supported by fermentation and anaerobic consumption of fermentation products oxidized by a variety of electron acceptors including NO3–, Fe(OH)3, and SO42–. Our results suggest that products of fermentation in the OMZ may provide a source of labile organics for advection to oxygenated waters of subantarctic origin during austral winter. Fermentation, anaerobic oxidation and associated advection of fermentation products are likely to be enhanced during the twenty-first century due both to temperature increase and decrease in dissolved O2 in the water column.Stephant, A., Anand, M., Tartèse, R., Zhao, X., Degli-Alessandrini, G., Franchi, I.A., 2020. The hydrogen isotopic composition of lunar melt inclusions: An interplay of complex magmatic and secondary processes. Geochimica et Cosmochimica Acta 284, 196-221. the discovery of water (a term collectively used for the total H, OH and H2O) in samples derived from the lunar interior, heterogeneity in both water concentration and its hydrogen isotopic ratio has been documented for various lunar phases. However, most previous studies have focused on measurements of hydrogen in apatite, which typically forms during the final stages of melt crystallisation. To better constrain the abundance and isotopic composition of water in the lunar interior, we have targeted melt inclusions (MIs), in mare basalts, that are trapped during the earliest stages of melt crystallisation. Melt inclusions are expected to have suffered minimal syn- or post-eruption modification processes, and, therefore, should provide more accurate information about the history of H in the lunar interior. Here, we report H?/18O? measurements as calibrated water concentrations, and hydrogen isotope ratios obtained by secondary ion mass spectrometry (SIMS) in a large set of basaltic MIs from Apollo mare basalts 10020, 10058, 12002, 12004, 12008, 12020, 12040, 14072 and 15016. Our results demonstrate that partially crystallised MIs from lunar basalts and their parental melts were influenced by a variety of processes such as hydrogen diffusion, degassing and assimilation of material affected by solar-wind implantation. Deconvolution of these processes show that lunar basaltic parental magmas were heterogeneous and had a broadly chondritic hydrogen isotopic composition with δD values varying between ?200 and +200‰.Stilo, F., Gabetti, E., Bicchi, C., Carretta, A., Peroni, D., Reichenbach, S.E., Cordero, C., Curry, J.M., 2020. A step forward in the equivalence between thermal and differential-flow modulated comprehensive two-dimensional gas chromatography methods. Journal of Chromatography A 1627, 461396. two-dimensional gas chromatography (GC×GC) based on flow-modulation (FM) is gaining increasing attention as an alternative to thermal modulation (TM), the recognized GC×GC benchmark, thanks to its lower operational cost and rugged performance. An accessible, rational procedure to perform method translation between the two platforms would be highly valuable to facilitate compatibility and consequently extend the flexibility and applicability of GC×GC. To enable an effective transfer, the methodology needs to ensure preservation of the elution pattern, separation power, and sensitivity. Here, a loop-type thermal modulation system with dual detection (TM-GC×GC-MSD/FID) used for the targeted analysis of allergens in fragrances is selected as reference method. Initially, six different columns configurations are systematically evaluated for the flow-modulated counterpart. The set up providing the most consistent chromatographic separation (20 m x 0.18 mm dc x 0.18 μm df?+?1.8 m x 0.18 mm dc x 0.18 μm df) is further evaluated to assess its overall performance in terms of sensitivity, linearity, accuracy, and pattern reliability. The experimental results convincingly show that the method translation procedure is effective and allows successful transfer of the target template metadata. Additionally, the FM-GC×GC-MSD/FID system is suitable for challenging applications such as the quantitative profiling of complex fragrance materials.Strojnik, L., Camin, F., Ogrinc, N., 2020. Compound-specific carbon and hydrogen isotope analysis of volatile organic compounds using headspace solid-phase microextraction. Talanta 219, 121264. flavouring materials are in high demand, and a premium price is paid for all-natural flavourings, making them vulnerable to fraud. At present, compound-specific isotope analysis (CSIA) is perhaps the most sophisticated tool for determining flavour authenticity. Despite promising results, the method is not widely used, and the results are limited to the most common volatile organic compounds (VOCs). This paper describes a robust protocol for on-line measurements of δ13C and δ2H using HS-SPME coupled with GC-C-IRMS and GC-HTC-IRMS for common fruit VOCs. To achieve reproducible and accurate results, a combination of a peak size/linearity correction with drift correction were used. Finally, the results were normalised by multiple point linear regression using the known and measured values of reference materials. Special care was taken to avoid irreproducible isotopic fractionation and the effects of equilibration, adsorption, desorption times and temperatures on δ13C or δ2H values were examined. Method validation was performed, and the average combined measurement uncertainty (MU) was 0.42‰. All the δ13CVPDB values were below ±3*MU, regardless of analytical conditions. In contrast, for δ2HVSMOW-SLAP values, only low temperature (30 °C) with equilibration time (15 min) and shorter adsorption time (between 10 and 20 min) can produce an isotopic difference of <10‰. Therefore, method optimisation can minimise MU, and data normalisation and method validation are essential for obtaining meaningful data for use in flavour authenticity studies.Stultz, C., Jaramillo, R., Teehan, P., Dorman, F., 2020. Comprehensive two-dimensional gas chromatography thermodynamic modeling and selectivity evaluation for the separation of polychlorinated dibenzo-p-dioxins and dibenzofurans in fish tissue matrix. Journal of Chromatography A 1626, 461311. two-dimensional gas chromatography (GC×GC) is a powerful tool for complex separations. The selectivity and sensitivity benefits from thermally modulated GC×GC were applied to the analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Thermodynamic indices of 50 PCDD/Fs, including the 17 toxic 2378-substituted congeners, were collected and used to model one-dimensional and two-dimensional separations with the Rtx-Dioxin2 and Rxi-17SilMS capillary GC columns. Thermodynamic modeling was used to determine the optimal conditions to take advantage of the selectivity differences between the Rxi-17SilMS and Rtx-Dioxin2 to separate all PCDD/Fs congeners from the 2378-substituted compounds by GC×GC. The modeled elution order patterns closely matched the experimental elution order in 40 of the 45 tetrachlorinated through hexchlorinated compounds analyzed. The heptachlorinated and octachlorinated congeners were not included in the elution order modeling as they are readily resolved from other dioxin congeners. The Rxi-17SilMS crossed with the Rtx-Dioxin2 was able to separate all 2378-substituted compounds in a single separation in a fish matrix. Thirty-three additional PCDD/F congeners were added to the fish matrix that coelute with the 2378-substituted congeners. The Rxi-17SilMS crossed with the Rtx-Dioxin2 was able to fully resolve 11 of the 2378-substituted congeners with the other six congeners exhibiting coelutions with only one other congener.Sturmer, D.M., Tempel, R.N., Soltanian, M.R., 2020. Geological carbon sequestration: Modeling mafic rock carbonation using point-source flue gases. International Journal of Greenhouse Gas Control 99, 103106. rocks are being considered as a key host for carbon dioxide (CO2) storage. This is a function of their global distribution and relative reactivity, resulting in CO2 mineralization. However, the reactivity of mafic minerals allows for reaction and sequestration of other gases associated with point source emissions. Though many mechanisms exist to separate CO2 from flue gas, these can be costly system additions for existing point source emitters. In this study, we model the effect of adding minor amounts of SO2 to CO2 during ex-situ mineral carbonation of basalt samples from Nevada, USA. We compare reaction path geochemical models at temperatures between 0° and 200?°C and at three different SO2 concentrations. Results from these models are compared to published data evaluating the interaction of these samples with CO2 only. The models have carbon trapped in four minerals (magnesite, siderite, dolomite, and dawsonite). Sulfur is sequestered as one sulfide (pyrite) and up to four sulfates (alunite, anhydrite, gypsum, and thenardite). With added SO2, between 43–161?grams of carbon are trapped per kg rock reacted. These models show -25 % to +18 % change in carbon sequestration, though decreases are more prevalent with increasing SO2. One major issue with adding SO2 as a reactant is pyrite precipitation, which may result in acid rock drainage from the reaction product. However, adding NO2 as a reactant inhibits pyrite formation by increasing oxygen fugacity. Ultimately, these methods can be used as an initial, inexpensive screening tool when evaluating between potential mafic rock carbonation projects.Sun, Y., Zhao, Y., Zhang, H., Zhang, C., 2020. Visualization of gas diffusion-sorption in coal: A study based on synchrotron radiation nano-CT. Geofluids 2020, 8835848. diffusion-sorption is a critical step in coalbed methane (CBM) exploitation and carbon dioxide sequestration. Because of the particularity of gas physical properties, it is difficult to visualize the gas diffusion-sorption process in coal by experimental methods. Due to the limitation of experimental approaches to image the three-dimensional coal pore structure, it is impossible to obtain the three-dimensional pore structure images of coal. As a result, the visualization of gas diffusion-sorption in coal pore structure by numerical ways is impossible. In this study, gas diffusion coefficients were firstly estimated by experiments. Then, a gas diffusion-sorption coupled model was developed which can be applied to the nanoscale geometry imaged by synchrotron radiation nano-CT. The dynamic process of gas diffusion and ad-/desorption in the nanoscale microstructure of coal was visualized by the developed gas diffusion-adsorption coupled model and the numerical simulation based on MATLAB. The simulation results show a good agreement with the experimental results. The gas diffusion-sorption coupled model and numerical method can help to investigate the effect of microstructure on gas diffusion and ad-/desorption and provides a possibility to investigate the multiscale gas transportation and adsorption in coal pore-fracture system.Suwaid, M.A., Varfolomeev, M.A., Al-muntaser, A.A., Yuan, C., Starshinova, V.L., Zinnatullin, A., Vagizov, F.G., Rakhmatullin, I.Z., Emelianov, D.A., Chemodanov, A.E., 2020. In-situ catalytic upgrading of heavy oil using oil-soluble transition metal-based catalysts. Fuel 281, 118753. this study, oil-soluble transition metal-based catalysts (Fe, Co, Ni) are proposed for catalyzing aquathermolysis reactions in steam injection process for heavy oil production to achieve in-situ upgrading of heavy oil. Their catalytic performance and possible mechanism were investigated by autoclave experiments together with a comprehensive analysis of the change in physical and chemical properties of the upgraded oil using SARA analysis, viscosity measurement, GC, GC–MS, FTIR, and 13C NMR, etc. Simultaneously, the in-situ transformation of these catalysts was also analyzed by TG-FTIR, XRD, and M?ssbauer spectra, etc. to better under the possible catalytic mechanism. The results showed that the in-situ transformation of these oil soluble catalysts occurred during the thermal treatment process at 250?°C and 300?°C, and their metal-based complexes, oxide, sulfide, and sometime pure metal were in-situ generated and played a catalytic role for aquathermolysis reactions. These catalysts showed a good catalytic performance at 300?°C for heavy oil upgrading in reducing viscosity, increasing saturates content (especially low molecule weight alkanes), decreasing resins and asphaltenes content, removing sulfur and nitrogen, and decreasing polyaromatics content, etc. by inhibiting the condensation and recombination reactions and promoting thermal decomposition reactions of heavy components (resin, asphaltene, and polycyclic aromatics, long chain alkanes, etc.) and hydrogenation reaction. Nickle gives the best catalytic performance. The low cost and easy access together with its high catalytic activity make its wide application a great potential in catalyzing aquathermolysis reaction in steam injection process for in-situ upgrading and heavy oil recovery.Sweere, T.C., Dickson, A.J., Jenkyns, H.C., Porcelli, D., Henderson, G.M., 2020. Zinc- and cadmium-isotope evidence for redox-driven perturbations to global micronutrient cycles during Oceanic Anoxic Event 2 (Late Cretaceous). Earth and Planetary Science Letters 546, 116427. study uses organic-rich sediments from the Tarfaya Basin, Morocco, to assess the Cd- and Zn-isotope response to dramatic global palaeoenvironmental change during the Cenomanian–Turonian interval (Late Cretaceous). These organic-rich continental-margin deposits include an expression of Oceanic Anoxic Event 2 (OAE 2, ～94 Ma), an interval associated with the spread of low-oxygen marine environments and widespread burial of organic-rich sediments. Due to placement of the Tarfaya Basin in a region of upwelling and relatively constant local environmental conditions, the stratigraphic variations in δ114Cd and δ66Zn values largely reflect changes in the seawater isotopic composition of the sub-surface proto-North Atlantic Ocean. Positive shifts of ～0.2–0.3‰ away from background values in δ114Cd and δ66Zn are observed during the main phase of the positive carbon-isotope excursion associated with OAE 2. These isotopic shifts are coeval with decreases in Cd/TOC and Zn/TOC ratios and thus imply that drawdown of isotopically light Cd and Zn from seawater inventories was a result of extensive burial of these metals in organic-rich marine sediments globally. Low δ66Zn values during the Plenus Cold Event, a cooler episode during OAE 2, are similar in timing and magnitude to variations found in the English Chalk (Eastbourne, UK) and support the inference of a global control on these isotopic excursions. The δ66Zn values during the Plenus Cold Event are taken to record global oxygenation, possibly including the remobilization of isotopically light Zn from continental-margin sediments. A considerably smaller change in δ114Cd values for this interval implies that the Cd- and Zn-isotope systems can provide information about slightly different environmental processes, with global seawater composition with respect to Zn also being influenced by the magnitude of oxic removal sinks and isotopically light Zn input fluxes from sediments and hydrothermal fluids.Szalwinski, L.J., Holden, D.T., Morato, N.M., Cooks, R.G., 2020. 2D MS/MS spectra recorded in the time domain using repetitive frequency sweeps in linear quadrupole ion traps. Analytical Chemistry 92, 10016-10023. trap mass spectrometers have emerged as powerful on-site analytical platforms, in spite of limited mass resolution, due to their compatibility with ambient ionization methods and ready implementation of tandem mass spectrometry (MS/MS). When operated at constant trapping voltage, ions can be activated at their secular frequencies and all MS/MS experiments can be performed, including the two-dimensional tandem mass scan (2D MS/MS scan) in which all precursor ions and their subsequent product ions are both identified and correlated. In the new method of performing this 2D MS/MS experiment presented here, the precursor ions are excited by a nonlinear (inverse Mathieu q) frequency sweep while the resulting product ions are identified by their ejection time within a repeating orthogonally applied nonlinear (inverse Mathieu q) frequency sweep. This resulting compact representation contains the total fragmentation behavior of a collection of ionized compounds and captures detailed chemical information efficiently (typically in 1 s). The approach is implemented using a simple single mass analyzer instrument. This methodology was tested on three different multicomponent mixtures: drugs of abuse, peptides, and fentanyl analogs. The data are compared with those obtained by more common MS/MS scan methods.Tajoddin, N.N., Konermann, L., 2020. Analysis of temperature-dependent H/D exchange mass spectrometry experiments. Analytical Chemistry 92, 10058-10067. exchange (HDX) mass spectrometry (MS) is a widely used technique for interrogating protein structure and dynamics. Backbone HDX is mediated by opening/closing (unfolding/refolding) fluctuations. In traditional HDX–MS, proteins are incubated in D2O as a function of time at constant temperature (T). There is an urgent need to complement this traditional approach with experiments that probe proteins in a T-dependent fashion, e.g., for assessing the stability of therapeutic antibodies. A key problem with such studies is the absence of strategies for interpreting HDX–MS data in the context of T-dependent protein dynamics. Specifically, it has not been possible thus far to separate T-induced changes of the chemical labeling step (kch) from thermally enhanced protein fluctuations. Focusing on myoglobin, the current work solves this problem by dissecting T-dependent HDX–MS profiles into contributions from kch(T), as well as local and global protein dynamics. Experimental profiles started off with surprisingly shallow slopes that seemed to defy the quasi-exponential kch(T) dependence. Just below the melting temperature (Tm) the profiles showed a sharp increase. Our analysis revealed that local dynamics dominate at low T, while global events become prevalent closer to Tm. About half of the backbone NH sites exhibited a canonical scenario, where local opening/closing was associated with positive ΔH and ΔS. Many of the remaining sites had negative ΔH and ΔS, thereby accounting for the shallowness of the experimental HDX–MS profiles at low T. In summary, this work provides practitioners with the tools to analyze proteins over a wide temperature range, paving the way toward T-dependent high-throughput screening applications by HDX–MS.Tanet, L., Martini, S., Casalot, L., Tamburini, C., 2020. Reviews and syntheses: Bacterial bioluminescence – ecology and impact in the biological carbon pump. Biogeosciences 17, 3757-3778. 30 species of marine bacteria can emit light, a critical characteristic in the oceanic environment is mostly deprived of sunlight. In this article, we first review current knowledge on bioluminescent bacteria symbiosis in light organs. Then, focusing on gut-associated bacteria, we highlight that recent works, based on omics methods, confirm previous claims about the prominence of bioluminescent bacterial species in fish guts. Such host–symbiont relationships are relatively well-established and represent important knowledge in the bioluminescence field. However, the consequences of bioluminescent bacteria continuously released from light organs and through the digestive tracts to the seawater have been barely taken into account at the ecological and biogeochemical level. For too long neglected, we propose considering the role of bioluminescent bacteria and reconsidering the biological carbon pump, taking into account the bioluminescence effect (“bioluminescence shunt hypothesis”). Indeed, it has been shown that marine snow and fecal pellets are often luminous due to microbial colonization, which makes them a visual target. These luminous particles seem preferentially consumed by organisms of higher trophic levels in comparison to nonluminous ones. As a consequence, the sinking rate of consumed particles could be either increased (due to repackaging) or reduced (due to sloppy feeding or coprophagy/coprorhexy), which can imply a major impact on global biological carbon fluxes. Finally, we propose a strategy, at a worldwide scale, relying on recently developed instrumentation and methodological tools to quantify the impact of bioluminescent bacteria in the biological carbon pump.Tang, C.A., Webb, A.A.G., Moore, W.B., Wang, Y.Y., Ma, T.H., Chen, T.T., 2020. Breaking Earth’s shell into a global plate network. Nature Communications 11, 3621. initiation mechanism of Earth’s plate tectonic cooling system remains uncertain. A growing consensus suggests that multi-plate tectonics was preceded by cooling through a single-plate lithosphere, but models for how this lithosphere was first broken into plates have not converged on a mechanism or a typical early plate scale. A commonality among prior efforts is the use of continuum mechanics approximations to evaluate this solid mechanics problem. Here we use 3D spherical shell models to demonstrate a self-organized fracture mechanism analogous to thermal expansion-driven lithospheric uplift, in which globe-spanning rifting occurs as a consequence of horizontal extension. Resultant fracture spacing is a function of lithospheric thickness and rheology, wherein geometrically-regular, polygonal-shaped tessellation is an energetically favored solution because it minimizes total crack length. Therefore, warming of the early lithosphere itself—as anticipated by previous studies—should lead to failure, propagating fractures, and the conditions necessary for the onset of multi-plate tectonics.Tang, L., Song, Y., Jiang, S., Jiang, Z., Li, Z., Yang, Y., Li, X., Xiao, L., 2020. Organic matter accumulation of the Wufeng-Longmaxi shales in southern Sichuan Basin: Evidence and insight from volcanism. Marine and Petroleum Geology 120, 104564. Wufeng-Longmaxi Formations (WF-LM Fms) in the Sichuan Basin are sets of graptolite-bearing shale strata containing high-frequency bentonite layers. In order to investigate the influence of volcanism on the organic matter (OM) accumulation in shales, detailed observations of several typical profiles and wells were performed. Also, analyses including total organic carbon (TOC) contents and mineral compositions were conducted on 126 shale and 5 bentonite core samples. Major and trace element analyses were conducted on the selected 25 shale and 5 bentonite samples in the WF-LM Fms of well Lu-A. Results show that WF and LM1-4 members are the bentonites concentrated sections, while LM5-6 are the bentonites relatively concentrated sections and no bentonite is found in LM7-9 members. The high potassium (K) content of bentonites have the typical characteristics of intermediate-acid calcium-alkaline volcanic rocks such as andesite and dacite, which probably originated from intraplate collision or volcanic arc structural backgrounds related to the collision belt of the Cathaysia Block to the Yangtze Block. Productivity indicators (P content, excess Si, P/Al, Cu/Al, and Ni/Al) in the WF and LM1-3 members are all significantly higher than those in the Lingxiang (LX) and LM4-5+ members. The higher biological productivity during the Ordovician-Silurian (O–S) transition was attributed to the massive and intensive volcanism. The fertilization by volcanic ash brought abundant biologically relevant nutrient elements (N, P, Si, Fe, and Al) into the ocean, thus triggering the phytoplankton bloom and enhancing primary biological productivity. All the redox condition indexes (MoEF, UEF, NiEF, VEF, Mo/TOC, Corg/P, and U/Th) positively correlate with TOC content. During the O–S transition, the intensive and massive volcanic eruptions triggered global cooling, sea-level changes, late Ordovician mass extinction, and primary productivity increases, thus promoting anoxic, and possibly intermittently euxinic bottom conditions. In addition, the deposited bentonite layers had a strong capacity for oxygen isolation. Volcanism should be considered when modeling the OM accumulation of the WF-LM shales.Tatzel, M., Stuff, M., Franz, G., Hippler, D., Wiechert, U., von Blanckenburg, F., 2020. Siliceous sponge expansion and phosphogenesis in a shallow water environment in the Malyi Karatau Range (Kazakhstan) during the Precambrian-Cambrian transition. Precambrian Research 347, 105830. oxygenation during the Precambrian-Cambrian transition is thought to be one of the key factors for the rapid diversification of animals, known as the ‘Cambrian Explosion’. Siliceous sponges inhabiting continental slope settings were capable of shifting the respiratory oxygen demand in the water column to depth, resulting in an increase in oxygen levels of shallow water. To assess the global importance of the impact of ecosystem engineering by sponges, we evaluated the palaeo-environmental conditions that confine sponge expansion using multiple geochemical proxies including silicon and carbon stable isotopes as well as major- and trace elements in cherts and siliceous sedimentary rocks that were deposited in shallow water around the Precambrian-Cambrian transition. We investigated three lithosections in the Malyi Karatau Range in southern Kazakhstan. The lowermost chert samples of these sections are typically characterized by comparably low δ30Si values and exhibit molds of siliceous sponge spicules. Upsection the occurrence of cross-bedding structures and granular phosphorites document the shallowing of the depositional environment, where overall increasing δ30Si values and increasing Al/Si indicate less settlement of sponges and higher suspended particle loads. Corresponding carbon isotope records of the carbonate fraction decrease from near-zero to negative carbon isotope values averaging ?5.9‰. The δ13Ccarb values overall coincide with Y/Ho, the redox indicator Ce/Ce*, and mass fractions of carbonate fluorapatite, suggesting that these ratios are predominantly controlled by the mineralization of organic matter in phosphatic sediment. The studied sections document the ecological requirements for sponge settlement and proliferation, such as the presence of a hard substrate and sufficiently low suspended particle concentrations and/or low wave energy. This work suggests that the widespread appearance of karsted surfaces around the Precambrian-Cambrian transition that were subsequently submerged during the Cambrian transgression would have created permissive habitats for sponges and large phosphate deposits. The capability of sponges to oxygenate shallow seawater and extensive phosphorous burial in epicontinental basins are thus feasible mechanisms for the seawater oxygenation around the Precambrian-Cambrian transition.Teehan, P., Schall, M.K., Blazer, V.S., Gruber, B., Dorman, F.L., 2020. Modified QuEChERS extraction for the analysis of young-of-year smallmouth bass using GC × GC-TOFMS. Analytical Methods 12, 3697-3704. of disease, such as external lesions, have been prevalent in smallmouth bass throughout the Susquehanna River Basin, USA. Previous targeted chemical studies in this system have identified known persistent organic pollutants, but a common explanatory link across multiple affected sites remains undetermined. A fast and robust extraction method that can be applied to young-of-year fish is needed to effectively screen for target and non-target compounds that may be impacting organism health. The quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction methodology was optimized to perform both targeted and non-targeted chemical analyses from a single extraction of whole young-of-year fish. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) was used for extract analysis. Sample extraction was performed using the solvent ethyl acetate, followed by a two-step cleanup in which samples were frozen for lipid removal and subjected to dispersive solid phase extraction using Florisil. A sample of 21 young-of-year smallmouth bass collected from areas with disease and exhibiting different types of external lesions were evaluated for 233 target compounds. A total of 34 organic contaminants, including polychlorinated biphenyls, brominated diphenyl ethers, organochlorinated pesticides, and personal care products, were detected. Data from this sample set was then analyzed for non-targets. Using the Fisher ratio method and multivariate analysis, an additional 10 significant features were identified specific to either fish with visible lesions or with no visible disease characteristics.Teixeira, P.D., Silva, V.S., Tenreiro, R., 2020. Integrated selection and identification of bacteria from polluted sites for biodegradation of lipids. International Microbiology 23, 367-380. treatment plants face major social concern towards removal of problematic pollutants such as fat oils and grease (FOG). In this context, the main objective of the present work was to select natural bacterial isolates from different polluted sites and evaluate them comparatively to isolates from commercial products, for improved bioremediation strategies and bioaugmentation. In total, 196 isolates were analysed for genomic diversity by two PCR-fingerprinting methods and screened for biodegradation potential with pollutants as sole carbon source. The net area under curve (NAUC) was used for preliminary evaluation of growth ability in M9 medium supplemented with oleic acid and triolein. A principal component analysis of all NAUC data showed that natural isolates presented higher overall biodegradation ability and enabled the selection of 11 natural isolates for lipid degradation assays. Selected isolates were identified by 16S rRNA gene sequencing as members of genera with previously described degradative strains, namely, Acinetobacter (1), Aeromonas (2), Bacillus (1), Pseudomonas (1) and Staphylococcus (6). Best biodegradation results in 7-days assay of FOG content removal were 37.9% for oleic acid and 19.1% for triolein by an Aeromonas sp. isolate and a Staphylococcus cohnii isolate, respectively. A respirometry approach confirmed their higher oxygen uptake rates, although longer adaptation phases where required by the Aeromonas sp. isolate. Consequently, these isolates showed great potential for future bioaugmentation products, to promote FOG degradation, for both in situ and ex situ approaches.Terada, K., Morota, T., Kato, M., 2020. Asteroid shower on the Earth-Moon system immediately before the Cryogenian period revealed by KAGUYA. Nature Communications 11, 3453. bombardment of the Earth-Moon system must have caused catastrophic damage to the terrestrial ecosphere. However, ancient meteoroid impacts and their relations to environmental changes are not well understood because of erosion and/or resurfacing processes on Earth. Here, we investigate the formation ages of 59 lunar craters with fresh morphologies and diameters greater than approximately 20?km and first find that 8 of 59 craters were formed simultaneously. Considering the radiometric ages of ejecta from Copernicus crater and impact glass spherules from various Apollo landing sites, we conclude that sporadic meteoroid bombardment occurred across the whole Moon at approximately 800?Ma. Based on crater scaling laws and collision probabilities with the Earth and Moon, we suggest that at least (4–5)?×?1016?kg of meteoroids, approximately 30–60 times more than the Chicxulub impact, must have plunged into the Earth-Moon system immediately before the Cryogenian, which was an era of great environmental changes.Terrell, E., Garcia-Perez, M., 2020. Novel strategy to analyze Fourier transform ion cyclotron resonance mass spectrometry data of biomass pyrolysis oil for oligomeric structure assignment. Energy & Fuels 34, 8466-8481. the most prominent challenges for the analysis of biomass pyrolysis products is the characterization of the abundant oligomer fraction of bio-oil. This fraction is principally made up of pyrolytic lignins and dehydrated, highly modified sugar oligomers, called humins, in liquid phase. An emerging technique for analysis of this oligomer fraction is high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), which allows for accurate determination of CxHyOz formulas for detected oligomers. Additionally, using simple dehydration and fragmentation reaction schemes, similar formulas can be developed from cellulose-, hemicellulose-, and lignin-derived oligomers, which are primary depolymerization products. In this study, FT-ICR MS analysis is coupled with combinatoric dehydration and fragmentation modeling to match experimentally detected bio-oil oligomers with hypothetical pathways for their formation during pyrolysis. In this way, we present a novel strategy by which oligomeric structures can be proposed for bio-oils. Using this approach, it becomes possible to advance the understanding of both the molecular structures comprising the bio-oil oligomer fraction and the pathways by which these structures form during biomass pyrolysis reactions.Thomas, E.K., Hollister, K.V., Cluett, A.A., Corcoran, M.C., 2020. Reconstructing Arctic precipitation seasonality using aquatic leaf wax δ2H in lakes with contrasting residence times. Paleoceanography and Paleoclimatology 35, e2020PA003886. precipitation is predicted to increase this century. Records of past precipitation seasonality provide baselines for a mechanistic understanding of the dynamics controlling Arctic precipitation. We present an approach to reconstruct Arctic precipitation seasonality using stable hydrogen isotopes (δ2H) of aquatic plant waxes in neighboring lakes with contrasting water residence times and present a case study of this approach in two lakes on western Greenland. Residence time calculations suggest that growing season lake water δ2H in one lake reflects summer precipitation δ2H, while the other reflects amount‐weighted annual precipitation δ2H and evaporative enrichment. Aquatic plant wax δ2H in the “summer lake” is relatively constant throughout the Holocene, perhaps reflecting competing effects of local summer warmth and increased distal moisture transport due to a strengthened latitudinal temperature gradient. In contrast, aquatic plant wax δ2H in the “mean annual lake” is 100‰ 2H depleted from 6 to 4 ka relative to the beginning and end of the record. Because there are relatively minor changes in summer precipitation δ2H, we interpret the 100‰ 2H depletion in mean annual precipitation to reflect an increase in winter precipitation amount, likely accompanied by changes in winter precipitation δ2H and decreased evaporative enrichment. Thus, unlike the “summer lake,” the “mean annual lake” records changes in winter precipitation. This dual‐lake approach may be applied to reconstruct past changes in precipitation seasonality at sites with strong precipitation isotope seasonality and minimal lake water evaporative enrichment.Thomas, G.E., Cameron, T.C., Campo, P., Clark, D.R., Coulon, F., Gregson, B.H., Hepburn, L.J., McGenity, T.J., Miliou, A., Whitby, C., McKew, B.A., 2020. Bacterial community legacy effects following the Agia Zoni II oil-spill, Greece. Frontiers in Microbiology 11, 1706. doi: 10.3389/fmicb.2020.01706. September 2017 the Agia Zoni II sank in the Saronic Gulf, Greece, releasing approximately 500 tonnes of heavy fuel oil, contaminating the Salamina and Athens coastlines. Effects of the spill, and remediation efforts, on sediment microbial communities were quantified over the following 7 months. Five days post-spill, the concentration of measured hydrocarbons within surface sediments of contaminated beaches was 1,093–3,773 μg g–1 dry sediment (91% alkanes and 9% polycyclic aromatic hydrocarbons), but measured hydrocarbons decreased rapidly after extensive clean-up operations. Bacterial genera known to contain oil-degrading species increased in abundance, including Alcanivorax, Cycloclasticus, Oleibacter, Oleiphilus, and Thalassolituus, and the species Marinobacter hydrocarbonoclasticus from approximately 0.02 to >32% (collectively) of the total bacterial community. Abundance of genera with known hydrocarbon-degraders then decreased 1 month after clean-up. However, a legacy effect was observed within the bacterial community, whereby Alcanivorax and Cycloclasticus persisted for several months after the oil spill in formerly contaminated sites. This study is the first to evaluate the effect of the Agia Zoni II oil-spill on microbial communities in an oligotrophic sea, where in situ oil-spill studies are rare. The results aid the advancement of post-spill monitoring models, which can predict the capability of environments to naturally attenuate oil.Thomazo, C., Couradeau, E., Giraldo-Silva, A., Marin-Carbonne, J., Brayard, A., Homann, M., Sansjofre, P., Lalonde, S.V., Garcia-Pichel, F., 2020. Biological soil crusts as modern analogs for the Archean continental biosphere: Insights from carbon and nitrogen isotopes. Astrobiology 20, 815-819. isotope signatures of elements related to life such as carbon and nitrogen can be powerful biomarkers that provide key information on the biological origin of organic remains and their paleoenvironments. Marked advances have been achieved in the last decade in our understanding of the coupled evolution of biological carbon and nitrogen cycling and the chemical evolution of the early Earth thanks, in part, to isotopic signatures preserved in fossilized microbial mats and organic matter of marine origin. However, the geologic record of the early continental biosphere, as well as its evolution and biosignatures, is still poorly constrained. Following a recent report of direct fossil evidence of life on land at 3.22 Ga, we compare here the carbon and nitrogen isotopic signals of this continental Archean biosphere with biosignatures of cyanobacteria biological soil crusts (cyanoBSCs) colonizing modern arid environments. We report the first extended δ13C and δ15N data set from modern cyanoBSCs and show that these modern communities harbor specific isotopic biosignatures that compare well with continental Archean organic remains. We therefore suggest that cyanoBSCs are likely relevant analogs for the earliest continental ecosystems. As such, they can provide key information on the timing, extent, and possibly mechanism of colonization of the early Earth's emergent landmasses.Thurber, A.R., Seabrook, S., Welsh, R.M., 2020. Riddles in the cold: Antarctic endemism and microbial succession impact methane cycling in the Southern Ocean. Proceedings of the Royal Society B: Biological Sciences 287, 20201134. is estimated to contain as much as a quarter of earth's marine methane, however we have not discovered an active Antarctic methane seep limiting our understanding of the methane cycle. In 2011, an expansive (70 m × 1 m) microbial mat formed at 10 m water depth in the Ross Sea, Antarctica which we identify here to be a high latitude hydrogen sulfide and methane seep. Through 16S rRNA gene analysis on samples collected 1 year and 5 years after the methane seep formed, we identify the taxa involved in the Antarctic methane cycle and quantify the response rate of the microbial community to a novel input of methane. One year after the seep formed, ANaerobic MEthane oxidizing archaea (ANME), the dominant sink of methane globally, were absent. Five years later, ANME were found to make up to 4% of the microbial community, however the dominant member of this group observed (ANME-1) were unexpected considering the cold temperature (?1.8°C) and high sulfate concentrations (greater than 24 mM) present at this site. Additionally, the microbial community had not yet formed a sufficient filter to mitigate the release of methane from the sediment; methane flux from the sediment was still significant at 3.1 mmol CH4 m?2 d?1. We hypothesize that this 5 year time point represents an early successional stage of the microbiota in response to methane input. This study provides the first report of the evolution of a seep system from a non-seep environment, and reveals that the rate of microbial succession may have an unrealized impact on greenhouse gas emission from marine methane reservoirs.Tignat-Perrier, R., Dommergue, A., Thollot, A., Magand, O., Vogel, T.M., Larose, C., 2020. Microbial functional signature in the atmospheric boundary layer. Biogeosciences Discussions 2020, 1-21. are ubiquitous in the atmosphere and some airborne microbial cells were shown to be particularly resistant to atmospheric physical and chemical conditions (e.g., UV radiation, desiccation, presence of radicals). In addition to surviving, some cultivable microorganisms of airborne origin were shown to be able to grow on atmospheric chemicals in laboratory experiments. Metagenomic investigations have been used to identify specific signatures of microbial functional potential in different ecosystems. We conducted a preliminary comparative metagenomic study on the overall microbial functional potential and specific metabolic and stress-related microbial functions of atmospheric microorganisms in order to determine whether airborne microbial communities possess an atmosphere-specific functional potential signature as compared to other ecosystems (i.e. soil, sediment, snow, feces, surface seawater etc.). In absence of a specific atmospheric signature, the atmospheric samples collected at nine sites around the world were similar to their underlying ecosystems. In addition, atmospheric samples were characterized by a relatively high proportion of fungi. The higher proportion of sequences annotated as genes involved in stress-related functions (i.e. functions related to the response to desiccation, UV radiation, oxidative stress etc.) resulted in part from the high concentrations of fungi that might resist and survive atmospheric physical stress better than bacteria.Tikariha, H., Purohit, H.J., 2020. Unfolding microbial community intelligence in aerobic and anaerobic biodegradation processes using metagenomics. Archives of Microbiology 202, 1269-1274. factors and available nutrients influence microbial communities, and with that, there exists a dynamic shift in community structure and hierarchy in wastewater treatment systems. Of the various factors, the availability and gradient of oxygen selectively enrich a typical microbial community and also form the community stratification which could be established through metagenomics studies. In recent years, metagenomics with various sets of bioinformatics tools has assisted in exploration and better insight into the organization and relation of the taxonomical and functional composition and associate physiological intelligence of the microbial communities. The microbial communities, under defined conditions acquire a typical?hierarchy with flexible but?active?network of the?metabolic?route, which ensures the survival needs of?every?member residing in that community and their abundance. This knowledge of community functional organization defines the rule in designing and improving biodegradation processes in case of both aerobic and anaerobic systems.Tinker, K., Gardiner, J., Lipus, D., Sarkar, P., Stuckman, M., Gulliver, D., 2020. Geochemistry and microbiology predict environmental niches with conditions favoring potential microbial activity in the Bakken Shale. Frontiers in Microbiology 11, 1781. doi: 10.3389/fmicb.2020.01781. Bakken Shale and underlying Three Forks Formation is an important oil and gas reservoir in the United States. The hydrocarbon resources in this region are accessible using unconventional oil and gas extraction methods, including horizontal drilling and hydraulic fracturing. However, the geochemistry and microbiology of this region are not well understood, although they are known to have major implications for productivity and water management. In this study, we analyzed the produced water from 14 unconventional wells in the Bakken Shale using geochemical measurements, quantitative PCR (qPCR), and 16S rRNA gene sequencing with the overall goal of understanding the complex dynamics present in hydraulically fractured wells. Bakken Shale produced waters from this study exhibit high measurements of total dissolved solids (TDS). These conditions inhibit microbial growth, such that all samples had low microbial loads except for one sample (well 11), which had lower TDS concentrations and higher 16S rRNA gene copies. Our produced water samples had elevated chloride concentrations typical of other Bakken waters. However, they also contained a sulfate concentration trend that suggested higher occurrence of sulfate reduction, especially in wells 11 and 18. The unique geochemistry and microbial loads recorded for wells 11 and 18 suggest that the heterogeneous nature of the producing formation can provide environmental niches with conditions conducive for microbial growth. This was supported by strong correlations between the produced water microbial community and the associated geochemical parameters including sodium, chloride, and sulfate concentrations. The produced water microbial community was dominated by 19 bacterial families, all of which have previously been associated with hydrocarbon-reservoirs. These families include Halanaerobiaceae, Pseudomonadaceae, and Desulfohalobiaceae which are often associated with thiosulfate reduction, biofilm production, and sulfate reduction, respectively. Notably, well 11 was dominated by sulfate reducers. Our findings expand the current understanding of microbial life in the Bakken region and provide new insights into how the unique produced water conditions shape microbial communities. Finally, our analysis suggests that produced water chemistry is tightly linked with microbiota in the Bakken Shale and shows that additional research efforts that incorporate coupled microbial and geochemical datasets are necessary to understand this ecosystem.Todd, Z.R., Fahrenbach, A.C., Ranjan, S., Magnani, C.J., Szostak, J.W., Sasselov, D.D., 2020. Ultraviolet-driven deamination of cytidine ribonucleotides under planetary conditions. Astrobiology 20, 878-888. previously proposed synthesis of pyrimidine ribonucleotides makes use of ultraviolet (UV) light to convert β-d-ribocytidine-2′,3′-cyclic phosphate to β-d-ribouridine-2′,3′-cyclic phosphate, while simultaneously selectively degrading synthetic byproducts. Past studies of the photochemical reactions of pyrimidines have employed mercury arc lamps, characterized by narrowband emission centered at 254?nm, which is not representative of the UV environment of the early Earth. To further assess this process under more realistic circumstances, we investigated the wavelength dependence of the UV-driven conversion of β-d-ribocytidine-2′,3′-cyclic phosphate to β-d-ribouridine-2′,3′-cyclic phosphate. We used constraints provided by planetary environments to assess the implications for pyrimidine nucleotides on the early Earth. We found that the wavelengths of light (255–285?nm) that most efficiently drive the deamination of β-d-ribocytidine-2′,3′-cyclic phosphate to β-d-ribouridine-2′,3′-cyclic phosphate are accessible on planetary surfaces such as those of the Hadean-Archaean Earth for CO2-N2-dominated atmospheres. However, continued irradiation could eventually lead to low levels of ribocytidine in a low-temperature, highly irradiated environment, if production rates are slow.Trail, D., Barboni, M., McKeegan, K.D., 2020. Evidence for diverse lunar melt compositions and mixing of the pre-3.9?Ga crust from zircon chemistry. Geochimica et Cosmochimica Acta 284, 173-195. samples collected during Apollo missions are typically impact-related breccias or regolith that contain amalgamations of rocks and minerals with various origins (e.g., products of igneous differentiation, mantle melting, and/or impact events). The largest intact pre-Nectarian (～≥3.92?Ga) fragments of igneous rock contained within the breccia and regolith rarely exceed 1?cm in size, and they often show evidence for impact recrystallization. This widespread mixing of disparate materials makes unraveling the magmatic history of pre-Nectarian period fraught with challenges. To address this issue, we combine U-Pb geochronology of Apollo 14 zircons (207Pb–206Pb ages from 3.93 to 4.36?Ga) with zircon trace element chemistry and thermodynamic models. Zircon crystallization temperatures are calculated with Ti-in-zircon thermometry after presenting new titania and silica activity models for lunar melts. We also present rare earth element (REE), P, actinide, and Mg?+?Fe?+?Al concentrations. While REE patterns and P yield little information about the parent melt origins of these out-of-context grains, U and Th concentrations are highly variable among pre-4.2?Ga zircons when compared to younger grains. Thus, the distribution of heat-producing radioactive elements in melt sources pervading the early lunar crust was heterogenous. Melt composition variation is confirmed by zircon Al concentrations and thermodynamic modeling that reveal at least two dominant magma signatures in the pre-4.0?Ga zircon population. One inferred magma type has a high alumina activity. This magma likely assimilated anorthosite-rich rocks (e.g., Feldspathic Highlands Terrane; FHT), though impact-generated melts of an alumina-rich target rock is a viable alternative. The other magma signature bears more similarities to KREEP basalts from the Procellarum KREEP Terrane (PKT), reflecting lower apparent alumina activities. Melt diversity seems to disappear after 4.0?Ga, with zircon recording magma compositions that largely fall in-between the two main groups found for pre-4.0?Ga samples. We interpret <4?Ga zircons to have formed from a mixture of KREEP basalts and FHT-like rocks, consistent with the upper ～15?km of the crust being thoroughly mixed and re-melted by basin-forming impacts during the pre-Nectarian period.Ubukata, M., Kubo, A., Nagatomo, K., Hizume, T., Ishioka, H., Dane, A.J., Cody, R.B., Ueda, Y., 2020. Integrated qualitative analysis of polymer sample by pyrolysis–gas chromatography combined with high-resolution mass spectrometry: Using accurate mass measurement results from both electron ionization and soft ionization. Rapid Communications in Mass Spectrometry 34, e8820.: Gas chromatography/mass spectrometry (GC/MS) is a powerful analytical tool used to separate and then identify volatile compounds through library database searches. However, as not all compounds are registered in these databases, it is not uncommon to detect unregistered components. Therefore, new analytical techniques were developed that utilize methods of identification beyond database searches alone.Methods: Acquire data by using electron ionization (EI) and soft ionization (SI) with high‐resolution mass spectrometry (HRMS). Use the EI mass spectra to library search for matches. Use the SI mass spectra for accurate mass analysis of the EI molecular ions. Conduct an isotope pattern analysis of the molecular ion to refine the possible candidate compositions. Use these compositions as a constraint for the accurate mass analysis of the EI fragment ions. If a given molecular ion formula is not correct, the EI fragment ions will not show good matches. Finally, all analytical results are integrated into a color‐coded qualitative analysis report.Results: The capabilities of this new integrated analytical method were assessed for a polymer resin sample that was measured by using pyrolysis–gas chromatography/high resolution time‐of‐flight mass spectrometry. A total of 161 compounds were detected in the total ion current chromatogram, and 154 of these compounds were identified as having only one chemical formula candidate with this new integrated qualitative analysis method.Conclusions: This new integrated qualitative analysis method gives analytical results independent of library search results. It can be applied to a variety of SI methods including chemical ionization, photoionization, field ionization, and low‐energy EI.Umezawa, K., Kojima, H., Kato, Y., Fukui, M., 2020. Disproportionation of inorganic sulfur compounds by a novel autotrophic bacterium belonging to Nitrospirota. Systematic and Applied Microbiology 43, 126110. phylum Nitrospirota (previously known as Nitrospirae or Nitrospira) currently encompasses a limited number of bacterial species with validly published names, including sulfate-reducing bacteria (SRB) of the genus Thermodesulfovibrio. Some metagenome-assembled genomes (MAGs) of bacteria occur in this phylum, and genes involved in dissimilatory sulfur metabolism have been identified in them. Currently, however, there is no established way to discriminate SRB and sulfur-disproportionating bacteria (SDB), which obtain energy from the disproportionation of inorganic sulfur compounds. In this study, a thiosulfate-disproportionating enrichment culture was established from a hot spring microbial mat. The culture was dominated by a single species belonging to the phylum Nitrospirota, and growth of the novel bacterium was supported by disproportionation of thiosulfate and elemental sulfur. Its growth was not observed under sulfate-reducing conditions. Therefore, a comparative genomic analysis of SDB and SRB was performed using its draft genome sequence, in order to identify any genetic element that could be used as a marker for SDB. As a result, a characteristic gene cluster was identified as a putative genetic element that characterized the genomes of SDB. The gene cluster was found in some MAGs of the phylum Nitrospirota, and their corresponding bacteria may also be capable of the disproportionation of inorganic sulfur compounds.Uzhansky, E., Katsnelson, B., Lunkov, A., Ostrovsky, I., 2020. Spatial and temporal variability of free gas content in shallow sediments: Lake Kinneret as a case study. Geo-Marine Letters 40, 491-505. aquatic sediments are a significant source of methane to the atmosphere. In situ remote quantifications of gas content in shallow sediment is a complex task due to its large spatiotemporal heterogeneity. The spatial and multiannual changes of free gas (methane) content (Θ) in shallow sediments were studied in deep subtropical Lake Kinneret. We implemented recently developed acoustic methodology that allows estimating Θ in sediment based on assessment of sound speed. This method is based on measurement of reflection coefficient of acoustic signal at low-to-mid frequencies from the water-sediment interface using geoacoustic inversion technique. The used approach provides an assessment of the mean gas content over certain bottom area near the sampling location. Analysis of acoustic measurements carried out in 2015–2018 shows distinct changes in Θ with bottom depth along the offshore transects. We found the inverse relationship between Θ and lake level. The observed patterns in sedimentary gas content are supported by previous observations showing (a) changes of acoustic sediment properties with depth and (b) inverse relationship between rate of gas ebullition from bottom and lake level. The obtained absolute values of Θ at different locations were the same order of magnitude as those estimated directly from frozen cores. The validity and reliability of the method and its further development are discussed.van Bree, L.G.J., Peterse, F., Baxter, A.J., De Crop, W., van Grinsven, S., Villanueva, L., Verschuren, D., Sinninghe Damsté, J.S., 2020. Seasonal variability and sources of in situ brGDGT production in a permanently stratified African crater lake. Biogeosciences Discussions 2020, 1-36. sediments are important archives of continental climate history, and their lipid biomarker content can be exploited to reconstruct paleoenvironmental conditions. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial membrane lipids widely used in paleoclimate studies to reconstruct past temperature. However, major gaps still exist in our understanding of the environmental controls on in situ (i.e., aquatic) production in lake systems. In Lake Chala, a permanently stratified tropical crater lake in East Africa, we determined the concentrations and fractional abundances of individual brGDGTs along depth profiles of suspended particulate matter (SPM) collected monthly from September 2013 to January 2015, and in settling particles collected monthly at 35 m water depth from August 2010 to January 2015, and compared these brGDGT distributions with those in surficial lake-bottom sediments and catchment soils. We find that brGDGTs are primarily produced within the water column, and that their concentrations and distributions vary greatly with depth and over time. Comparison with concentration-depth profiles of the monthly distribution and abundance of bacterial taxa, based on 16S rRNA gene amplicon sequencing and quantification, indicates that Acidobacteria are likely not the main producers of brGDGTs in Lake Chala. Shallowing of the oxic-anoxic boundary during seasonal episodes of strong water-column stratification promoted production of specific brGDGTs in the anoxic zone. BrGDGT distributions in the water column do not consistently relate with temperature, pH, or dissolved-oxygen concentration, but do respond to transitions between episodes of strong stratification and deep (but partial) lake mixing, as does the aquatic bacterial community. Hence, the general link between brGDGT distributions and temperature in brGDGT-based paleothermometry is more likely driven by a change in bacterial community composition than by membrane adaptation of specific members of the bacterial community to changing environmental conditions. Although temperature is not the principal driver of distributional changes in aquatic brGDGTs in this system, at least not during the 17-month study period, abundance-weighted and time-integrated averages of brGDGT fractional abundance in the 53-month time series of settling particles reveal systematic variability over longer time scales that indirectly relates to temperature. Thus, although we do not as yet fully understand the drivers of modern-day brGDGT fluxes and distributions in Lake Chala, our data do support the application of brGDGT paleothermometry to time-integrated archives such as sediments.Varjani, S., Pandey, A., Upasani, V.N., 2020. Oilfield waste treatment using novel hydrocarbon utilizing bacterial consortium — A microcosm approach. Science of The Total Environment 745, 141043. sludge is a hazardous waste generated through petroleum producing and processing industrial units. Due to its harmful environmental impacts, it needs to be treated in sustainable manner. The present study aimed to evaluate influence of bioaugmentation on oily sludge biodegradation efficiency of a novel hydrocarbon utilizing bacterial consortium (HUBC) using microcosms. Three approaches (bioaugmentation, natural attenuation and abiotic factors) were used for microcosm studies. Bioaugmentation treatment showed best results for oily sludge degradation than natural attenuation and abiotic factors, resulting 82.13 ± 1.21% oily sludge degradation in 56 days. In bioaugmented microcosm on 56th day 0.30 ± 0.07 × 108 CFU/g hydrocarbon utilizing bacteria were noted. Results showed that HUBC could be used to remediate soil polluted with oily sludge. This study imparts a notable approach for farming application(s).Vasconcelos, F.A., Pilling, S., Agnihotri, A., Rothard, H., Boduch, P., 2020. Methylenimine and cyanomethanimine synthesis from ion irradiation of N2-CH4 ice: Implication on the formation of prebiotic molecules in outer solar system bodies. Icarus 351, 113944. synthesis of methylenimine and cyanomethanimine from ion irradiation of N2-CH4 ice was studied, in an attempt to simulate the role of medium mass cosmic rays and energetic solar particles in the processing of nitrogen-rich ices on cold astrophysical environments, such as those in the outer region of the solar system (e.g. Pluto, Charon, Triton, Makemake and Titan). The N2-CH4 (90:10) ice mixture was irradiated at 9 K by 38.4 MeV 40Ca9+ (0.96 MeV/u) at the GANIL facility (Caen/Fance). The evolution of the samples was monitored using in-situ Fourier transform infrared spectroscopy (FTIR). The results indicate the formation of CH2NH and CH2NCN, which are considered species of interest in prebiotic chemistry. Other species produced by radiolysis were HCN, HNC, hydrocarbons and nitriles. Direct comparison of the laboratory spectrum from the mixture of reaction products provides an efficient way to focus on the identification of chemical synthesis routes for the production of molecules important in the development of life that are consistent with the chemical inventory and physical conditions on frozen moons and cold objects in the outer solar system.Vecchiato, M., Gambaro, A., Kehrwald, N.M., Ginot, P., Kutuzov, S., Mikhalenko, V., Barbante, C., 2020. The Great Acceleration of fragrances and PAHs archived in an ice core from Elbrus, Caucasus. Scientific Reports 10, 10661. Great Acceleration of the anthropogenic impact on the Earth system is marked by the ubiquitous distribution of anthropogenic materials throughout the global environment, including technofossils, radionuclides and the exponential increases of methane and carbon dioxide concentrations. However, personal care products as direct tracers of human domestic habits are often overlooked. Here, we present the first research combining fragrances, as novel personal care products, and polycyclic aromatic hydrocarbons (PAHs) as combustion and industrial markers, across the onset of the Great Acceleration in the Elbrus, Caucasus, ice core. This archive extends from the 1930s to 2005, spanning the profound changes in the relationship between humans and the environment during the twentieth century. Concentrations of both fragrances and PAHs rose throughout the considered period, reflecting the development of the Anthropocene. However, within this rising trend, remarkable decreases of the tracers track the major socioeconomic crises that occurred in Eastern Europe during the second half of the twentieth century.Veerasingam, S., Al-Khayat, J.A., Haseeba, K.P., Aboobacker, V.M., Hamza, S., Vethamony, P., 2020. Spatial distribution, structural characterization and weathering of tarmats along the west coast of Qatar. Marine Pollution Bulletin 159, 111486. pollution resulting from natural and anthropogenic activities in the Arabian Gulf as well as oil residue in the form of tarmat (TM) deposited on the coast is a major environmental concern. The spatial distribution, chemical composition and weathering pattern of tarmat along the west coast of Qatar has been assessed based on the TM samples collected from 12 coastal regions. The range of TM distribution is 0–104 g m?1 with an average value of 9.25 g m?1. Though the current TM level is thirty-fold lesser than that was found during 1993–1997 (average 290 g m?1), the distribution pattern is similar. The results of ATR-FTIR spectroscopy indicate that aromatic compounds are higher in the north (N) coast TMs than those found in the northwest (NW) and southwest (SW) coasts, and Carbonyl Index values indicate that TM of NW coast is highly weathered compared to those found in the N and SW coasts.Verma, A., Pal, Y., Kumar, P., Krishnamurthi, S., 2020. Halocatena pleomorpha gen. nov. sp. nov., an extremely halophilic archaeon of family Halobacteriaceae isolated from saltpan soil. International Journal of Systematic and Evolutionary Microbiology 70, 3693-3700. novel archaeal strain designated as SPP-AMP-1T was isolated from saltpan soil, using the serial dilution method on a halophilic archaeal medium supplemented with ampicillin. Cells were both rod-shaped and pleomorphic in nature, non-motile, unable to produce acid from a variety of sugars or grow anaerobically with different substrates (l-arginine) and electron acceptors (DMSO, nitrate). Optimal growth was observed at 42?°C, 3.4–4.2 M NaCl and pH 7.2. Cells did not lyse in distilled water and grew in the absence of Mg2+ ions. Phylogenetic analysis based on the sequences of 16S rRNA gene, amino acid sequence of β′-subunit of RNA polymerase and 400 conserved proteins retrieved from the whole genome assemblies showed that strain SPP-AMP-1T was distantly related to any existing genera within the family Halobacteriaceae . MK-8 was the only quinone detected. Polar lipid analysis showed a unique combination of diethyl derivatives of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, glycosyl-mannosyl-glucosyl diether and sulphated glycosyl-mannosyl-glucosyl diether as the major lipids. The G+C content of genomic DNA is 57.7 mol%. The phenotypic, phylogenetic and genomic data supported the concept of the novel genus status of strain SPP-AMP-1T in the family Halobacteriaceae for which the name Halocatena pleomorpha gen. nov., sp. nov., is proposed; the type strain is SPP-AMP-1T (=JCM 31368T=KCTC 4276T=MTCC 12579T).Versteegh, G.J.M., Houben, A.J.P., Zonneveld, K.A.F., 2020. Better molecular preservation of organic matter in an oxic than in a sulfidic depositional environment: evidence from Thalassiphora pelagica (Dinoflagellata, Eocene) cysts. Biogeosciences 17, 3545-3561. sediments, as compared to oxic settings, encompass a much higher proportion of relatively labile and thus more reactive organic matter, naturally giving rise to structural changes of the organic molecules themselves, as well as cross-linking between them (e.g., through reactive sulfur species). Both processes transform the original biomolecules into geomolecules. For the oxic environment, these intermolecular and intramolecular transformations also operate, but cross-linking may be less important since the labile, reactive component is rapidly removed. As such, one may expect a structurally better preservation of the more refractory initial biomolecules in the oxic environment. To test this hypothesis, initially identical biomolecules need to be compared between different preservational environments. Here, we use the species-specific morphology of organic microfossils to assure a single initial biosynthetic product (the cysts of the fossil dinoflagellate species Thalassiphora pelagica) for comparison. We assess the macromolecular structures of cysts from the Eocene (～40?Ma) sulfidic Rhine Graben and the oxic Kerguelen Plateau and compare them with each other and the structures of recent cysts. While between the sites the T. pelagica cysts are morphologically identical and show no signs of morphological modification, pyrolysis gas chromatography mass spectroscopy and micro Fourier transform infrared analyses show that their macromolecular characteristics are strongly different. Comparison with recent cysts shows that the cysts deposited in the sulfidic Rhine Graben show a strong additional contribution of long-chain aliphatic moieties and thus less diagenetic intermolecular cross-linking. The presence of organic sulfur identifies natural volcanization as one of the diagenetic processes. Furthermore, we observe a loss of bound oxygen and no trace of the original carbohydrate signature of the cyst wall biomacromolecule. The material deposited in the oxic sediments of the Kerguelen Plateau shows no traces of sulfurization. It shows a minor contribution of short carbon chains only and thus less diagenetic intermolecular cross-linking. Furthermore, a carbohydrate signature was still preserved evidencing a better molecular preservation of the initial biomacromolecule, supporting our initial hypothesis. This shows that excellent morphological preservation does not imply excellent chemical preservation. It also leads to the conclusion that the best preservation of molecular structure is not necessarily where most organic matter gets preserved, which, in turn, is important for understanding the nature and fate of sedimentary organic matter and its isotopic signature.Vilbaste, M., Tammekivi, E., Leito, I., 2020. Uncertainty contribution of derivatization in gas chromatography/mass spectrometric analysis. Rapid Communications in Mass Spectrometry 34, e8704.: The purpose of the current work is to realistically assess the uncertainty contribution in gas chromatography/mass spectrometry (GC/MS) analysis originating from less‐than‐ideal derivatization efficiency.Methods: As the exemplary analytical method a two‐step derivatization method with KOH and BSTFA (N ,O‐bis(trimethylsilyl)trifluoroacetamide), applied for the analysis of fatty acid triglycerides (using real measurement data), was selected. The derivatization efficiencies were in the range 0.89–1.04. In this study, two approaches for bottom‐up uncertainty evaluation were compared: the traditional GUM approach and the Monte Carlo method (MCM). Both were used with and without taking correlation between input quantities into account. Results: The most reliable uncertainty estimates were in the range 0.07–0.08 (expanded uncertainties at 95% coverage probability). A strong negative correlation was found between the slope and intercept of the calibration graph (r ?=??0.71) and it markedly influenced the uncertainty estimate of derivatization efficiency. The MCM was found to give somewhat higher uncertainty estimates, which are considered more realistic. Conclusions: Derivatization directly affects the analysis result. Thus, in the case of this exemplary analysis, just derivatization alone (i.e. if all other uncertainty sources are neglected) causes relative expanded uncertainty around 8%, being thus an important and in some cases the dominant uncertainty contributor.Vimercati, L., Bueno de Mesquita, C.P., Schmidt, S.K., 2020. Limited response of indigenous microbes to water and nutrient pulses in high-elevation Atacama soils: Implications for the cold–dry limits of life on Earth. Microorganisms 8, 1061. on the world’s highest volcanoes in the Atacama region represent some of the harshest ecosystems yet discovered on Earth. Life in these environments must cope with high UV flux, extreme diurnal freeze–thaw cycles, low atmospheric pressure and extremely low nutrient and water availability. Only a limited spectrum of bacterial and fungal lineages seems to have overcome the harshness of this environment and may have evolved the ability to function in situ. However, these communities may lay dormant for most of the time and spring to life only when enough water and nutrients become available during occasional snowfalls and aeolian depositions. We applied water and nutrients to high-elevation soils (5100 meters above sea level) from Volcán Llullaillaco, both in lab microcosms and in the field, to investigate how microbial communities respond when resource limitations are alleviated. The dominant taxon in these soils, the extremophilic yeast Naganishia sp., increased in relative sequence abundance and colony-forming unit counts after water + nutrient additions in microcosms, and marginally in the field after only 6 days. Among bacteria, only a Noviherbaspirillum sp. (Oxalobacteraceae) significantly increased in relative abundance both in the lab and field in response to water addition but not in response to water and nutrients together, indicating that it might be an oligotroph uniquely suited to this extreme environment. The community structure of both bacteria and eukaryotes changed significantly with water and water + nutrient additions in the microcosms and taxonomic richness declined with amendments to water and nutrients. These results indicate that only a fraction of the detected community is able to become active when water and nutrients limitations are alleviated in lab microcosms, and that water alone can dramatically change community structure. Our study sheds light on which extremophilic organisms are likely to respond when favorable conditions occur in extreme earthly environments and perhaps in extraterrestrial environments as well.Vinnepand, M., Fischer, P., Fitzsimmons, K., Thornton, B., Fiedler, S., V?tt, A., 2020. Combining inorganic and organic carbon stable isotope signatures in the Schwalbenberg loess-palaeosol-sequence near Remagen (Middle Rhine Valley, Germany). Frontiers in Earth Science 8, 276. doi: 10.3389/feart.2020.00276. Central European Loess-Palaeosol-Sequences (LPS) provide valuable terrestrial records of palaeoenvironmental conditions, which formed in response to variability in the North Atlantic climate systems. Over the last full glacial cycle (～130 ka), climate oscillations within these systems are best documented in deep sea- and ice cores; the responses of terrestrial systems are not yet fully understood. A better understanding of metabolism governing input and output variables of organic- and inorganic C pools is, however, crucial for investigating landscape-atmospheric feedback processes and in particularly, for understanding the formation of calcareous LPS as environmental archives. Here we quantify the contributions of primary carbonates (PC) and secondary carbonates (SC) to the overall inorganic carbon pool down a LPS at the Schwalbenberg site, based on the natural abundance ratio of stable carbon isotopes (δ13C) and contents of the organic- and inorganic C pools. This facilitates detailed insights into the carbonate metabolism and hence, loessification and percolation processes. PC accumulate predominantly in cold phases during periods of reduced biological activity and become leached during wetter and warmer periods contemporary with higher rates of SC re-precipitation and total organic carbon (TOC) increases due to enhanced biomass production. We find that mineral dust input is most significant during stadials, as well as toward the end of warmer interstadials, characterised by gradual cooling back to stadial conditions. Pedogenesis in the Schwalbenberg LPS kept pace with surface accumulation of mineral dust. This indicates that palaeosols are of accretionary nature, which gives raise to the idea of incorporation of former topsoils in preserved subsoil horizons. Our study decodes fundamental aspects of the link between atmospheric dust circulation and terrestrial records in western Central Europe. In addition, interdependencies between factors governing the regional moisture budged and LPS can be reconstructed in a more holistic way than before.Vishal, V., Lall, D., Sarna, S., Sharma, A., Ranjith, P.G., 2020. Sensitivity analysis of methane hydrate bearing Class 3 reservoirs during thermal injection. Journal of Petroleum Science and Engineering 195, 107575. analysis is required for the different geological settings of methane hydrate–bearing reservoirs in order to understand the effects of reservoir parameters (such as permeability, porosity, sediment grain density) as well as the role of production parameters (such as injection rate, injected fluid salinity) during methane production. In this study, a sensitivity analysis was conducted using the one-factor-at-a-time (OFAT) approach of thermal stimulation in a Class 3 reservoir. A 2–D cylindrical grid was chosen such that mesh convergence was reached in both radial and vertical directions. Upon analysis, injection flow rate was obtained to be the most crucial parameter since the process of dissociation was driven thermally and this parameter dictated the net thermal energy supplied to the reservoir. The second most important parameter was identified as permeability in the range of 10mD to 30mD. Incidentally, permeability in the range of 50mD to 100mD was the least crucial parameter. This was because increase of permeability in the lower ranges significantly increased the dissociated methane volume due to improved thermal energy distribution due to improved fluid flow. However, at higher permeability, further improvements in fluid flow did not lead to increased dissociation since the thermal energy was limited by the injection flow rate. Thus, artificially increasing permeability in the hydrate bearing reservoir is crucial up to an optimal permeability value, beyond which the dissociated volume would be limited by the net thermal energy available. Multiple production scenarios were also studied using the huff and puff method with varying injection duration, soaking times and production rates w.r.t their recovery efficiency. The scenario which did not include any soaking stage outperformed all the other scenarios. Also, prolonging the duration of the injection duration exhibited a decline in gas produced. The energy efficiency was calculated for the most optimal scenario, but even that was found to be economically infeasible.Vrkoslav, V., Rumlová, B., Strmeň, T., Cva?ka, J., 2020. Temperature-programmed capillary high-performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry for analysis of fatty acid methyl esters. Journal of Separation Science 43, 2579-2588. new capillary high‐performance liquid chromatography method with atmospheric pressure chemical ionization mass spectrometry was developed for the analysis of fatty acid methyl esters and long‐chain alcohols. The chromatographic separation was achieved using a Zorbax SB‐C18 HPLC column (0.3 × 150 mm, 3.5 μm) with a mobile phase composed of acetonitrile and formic acid and delivered isocratically at a flow rate of 10 μL/min. The column temperature was programmed simply, using a common column oven. Good reproducibility of the temperature profile and retention times were achieved. The temperature programming during the isocratic high‐performance liquid chromatography run had a similar effect as a solvent gradient; it reduced retention times of later eluting analytes and improved their detection limits. Two atmospheric pressure chemical ionization sources of the mass spectrometry detector were compared: an enclosed conventional ion source and an in‐house made ion source with a glass microchip nebulizer. The enclosed source provided better detectability of saturated fatty acid methyl esters and made it possible to determine the double bond positions using acetonitrile‐related adducts, while the open chip‐based source provided better analytical figures of merit for unsaturated fatty acid methyl esters. Temperature‐programmed capillary high‐performance liquid chromatography is a promising method for analyzing neutral lipids in lipidomics and other applications.Wakabayashi, K., Soga, K., Hoson, T., Kotake, T., Yamazaki, T., Ishioka, N., Shimazu, T., Kamada, M., 2020. Microgravity affects the level of matrix polysaccharide 1,3:1,4-β-glucans in cell walls of rice shoots by increasing the expression level of a gene involved in their breakdown. Astrobiology 20, 820-829. plant cell wall provides each cell with structural support and mechanical strength, and thus, it plays an important role in supporting the plant body against the gravitational force. We investigated the effects of microgravity on the composition of cell wall polysaccharides and on the expression levels of genes involved in cell wall metabolism using rice shoots cultivated under artificial 1 g and microgravity conditions on the International Space Station. The bulk amount of the cell wall obtained from microgravity-grown shoots was comparable with that from 1 g-grown shoots. However, the analysis of sugar constituents of matrix polysaccharides showed that microgravity specifically reduced the amount of glucose (Glc)-containing polysaccharides such as 1,3:1,4-β-glucans, in shoot cell walls. The expression level of a gene for endo-1,3:1,4-β-glucanase, which hydrolyzes 1,3:1,4-β-glucans, largely increased under microgravity conditions. However, the expression levels of genes involved in the biosynthesis of 1,3:1,4-β-glucans were almost the same under both gravity conditions. On the contrary, microgravity scarcely affected the level and the metabolism of arabinoxylans. These results suggest that a microgravity environment promotes the breakdown of 1,3:1,4-β-glucans, which, in turn, causes the reduced level of these polysaccharides in growing rice shoots. Changes in 1,3:1,4-β-glucan level may be involved in the modification of mechanical properties of cell walls under microgravity conditions in space.Waktola, H.D., Zeng, A.X., Chin, S.-T., Marriott, P.J., 2020. Advanced gas chromatography and mass spectrometry technologies for fatty acids and triacylglycerols analysis. TrAC Trends in Analytical Chemistry 129, 115957. dimension gas chromatography (GC) is widely used for the analysis of a broad variety of lipid samples of a multitude of origins, most often used as a GC method in combination with mass spectrometry (MS). However, adequate characterisation and accurate identification of fatty acids (FAs) and triacylglycerols (TAGs) remain challenging due to their complexity, incomplete resolution on the separation dimension often confounded by sample matrix, and sometimes insufficient MS domain differentiation. The higher resolution of multidimensional separation enables improved quality separations that should translate to better reliability of identification and more precise analytical characterisation of major and minor abundance FA isomers that contribute nutrition and health benefits, and for compounds that can be used for medical and pharmaceutical purposes. Development of advanced multidimensional chromatographic strategies incorporating multiple separations coupled with different detection tools, including multistage-MS (MSn) methods for FA in various foods, environmental and biological samples is described.Wang, A., Cao, D., Nie, J., Qin, R., 2020. Vertical heterogeneity characteristics of pore structure for huge thick coal reservoirs: a case study of Juhugeng mining area in Qinghai province Acta Petrolei Sinica 41, 691-701. Jurassic huge thick coal reservoirs are widely developed in coal-bearing basins in northern China. Taking the Juhugeng mining area in Qinghai as the study area, using SEM, mercury injection, low-temperature liquid nitrogen and other experimental methods, this paper explores the vertical heterogeneity characteristics of pore structure of the Middle Jurassic huge thick coal reservoirs. The results show that there are more pores with good structure developed in fusinite and semifusinite. The higher the content of fusinite and semifusinite, the less complex the pore structure of the sample. Pores are less developed in heterocollinite and homocollinite. The higher the content of heterocollinite and homocollinite, the stronger the heterogeneity of pore structure of the sample. Based on the vitrinite/intertinite ratio and gelation index, the huge thick coal reservoirs in the study area are classified into three regression cycles, i.e., Cycle Ⅰ, Cycle Ⅱ and Cycle Ⅲ. The fractal dimension of the macro and small pores shows a decrease with regression, and the pore volume of macropores and mesopores and the porosity of mesopores increase with regression. The fact is that the regression leads to an increase in the content of fusinite and semifusinite, so that the pore volume increases and pore structure is less complex. The comparison of pore structures of the three cycles indicates that Cycle Ⅰ has poorer pore connectivity than Cycle Ⅱ and Cycle Ⅲ. Overall, the porosity distribution is shown as Cycle Ⅰ > Cycle Ⅱ > Cycle Ⅲ; the complexity of the macropore structure is shown as Cycle Ⅲ > Cycle Ⅰ > Cycle Ⅱ, the complexity of the mesopore pore structure is shown as Cycle Ⅰ > Cycle Ⅱ > Cycle Ⅲ, and there is no much difference in the pore structure of small pores in each cycle. It is an effective method to study the physical properties of huge thick coal reservoirs by dividing the cyclicity and comparing the differences in pore structure of each cycle, which can provide certain theoretical support for the reservoir evaluation and exploration and development of huge thick coal reservoirs.Wang, A., Li, J., Wei, Y., Yang, C., Nie, J., Cao, D., 2020. Gas migration for terrestrial gas hydrates in the Juhugeng mining area of Muli basin, Qilian Mountains, Northwest China. Energy Exploration & Exploitation 38, 989-1013. Juhugeng mining area in the Qilian Mountains is the only district of China where terrestrial gas hydrate has been found. This paper aimed at studying the gas migration for gas hydrates based on fluid inclusion and apatite fission track experiments with samples being collected in both the hanging wall (Triassic strata, non-hydrocarbon source rocks) and footwall (Jurassic strata, hydrocarbon source rocks) of drilling cores. Fluid inclusions are found in both the hanging wall and footwall, and are characterized by two generations: the first generation includes gaseous and liquid hydrocarbon fluid inclusions with the homogenization temperature of concomitant saline water inclusions being 83–115°C, and the second generation includes gaseous fluid inclusions with the concomitant homogenization temperature of saline water inclusions being 115–149?°C, suggesting two periods of gas migration. Combining with the reconstruction of the burial and thermal histories, the gas migration history can be elaborated as follows: (1) In the Late Paleogene period (>30 Ma), the gas in the footwall migrated to the hanging wall because of the thrusting of Triassic strata, with the temperature being more than 110?±?10°C (derived from apatite fission track results), corresponding well with the homogenization temperature of the saline water inclusions of the first generation being 115–149?°C; (2) In the Late Neogene to Quaternary (<8 Ma), the study area were impacted by the intensive faults, leading to the second gas migration with a good match between temperature lower than 110?±?10°C (derived from apatite fission track results) and the homogenization temperature of saline water inclusions in the second generation (83–115?°C), and the geological age of the second gas migration can be restricted from 8 to 1.8 Ma. The permafrost was formed in Quaternary, so the controversial gas hydrate formation pattern can be determined that the gas should be accumulated before the permafrost was formed.Wang, A., Yi, L., Xiang, B., Li, J., Fan, C., Li, C., Zhou, N., Wang, Y., 2020. Origin of deep heavy oils in the northwestern Junggar Basin (NW China) and implications for gas migration. Energy Exploration & Exploitation 38, 819-840. the northwestern Junggar Basin (NW China) has natural gas potential is an urgent but unresolved question. In this study, we discuss the origin of deep heavy oils (>2900?m) and its implication for gas migration and accumulation, based on a comprehensive investigation into physicochemical and geological properties of hydrocarbons in the northern Zhongguai High. Our results indicate that multiple-episode migration of hydrocarbons created four genetic types of oils and three genetic types of hydrocarbon gases and induced widespread gas washing. Relatively low maturity and gas washing are both responsible for the formation of the deep heavy oils. In detail, the migrating late-stage humic-type gases washed the encountered early stage low-maturity oils. The oil reservoirs lost their light fraction and evolved into heavy oils, which are preserved in the deep layer to the present, while the light-end components continued to migrate upward and accumulated as mixed gas pools or vented out of the system. The spatial distributions pattern of source rocks, heavy oils, and mixed gas clearly indicates the migration pathways of humic-type gases, which otherwise are difficult to define in the study area. Because the gases finally migrate into fault belts, their poor preservation condition likely results in the rare discoveries of gas fields. The favorable exploration targets for gas in the area are expected to be fault traps in fault belts, stratigraphic traps along the pinch-out boundary of the Upper Wuerhe Formation, and, particularly, the deep traps in the Mahu Sag.Wang, C., Wang, C., Liu, J., Han, Z., Xu, Q., Xu, X., Zhu, L., 2020. Role of magnetite in methanogenic degradation of different substances. Bioresource Technology 314, 123720. better understanding the role of magnetite in methanation of different substrates, two up-flow anaerobic sludge bed reactors (RM with magnetite; RS with silica) were built using acetate (stage I), propionate + butyrate (stage II), and sucrose (stage III) as the substrates, respectively. RM reactor showed better COD removal efficiency and adaptability to different substrate impacts. More extracellular polymeric substances (EPS) were produced for anaerobic sludge granulation, and the sludge in RM had better intensity, hydrophobicity and electroactivity compared with those in RS. Interestingly, magnetite had different promoting effects on methanogenic degradation of different substrates, and magnetite facilitated different syntrophic partners, like Desulfovibrio, Smithella, unidentified Clostridiates and Methanosaeta in different stages. The strengthening factor of biogas production from sucrose was the highest (1.23 ± 0.03), and analysis of key enzyme activities indicated that the potential magnetite-induced direct interspecies electron transfer (DIET) improved the process between the glycolysis, oxidation of pyruvate and CO2-dependent methanogenesis.Wang, D., He, P., Wang, Z., Li, G., Majed, N., Gu, A.Z., 2020. Advances in single cell Raman spectroscopy technologies for biological and environmental applications. Current Opinion in Biotechnology 64, 218-229. increasing sophistication of single cell Raman spectroscopy (SCRS) via its integrations with other advanced analytical techniques and modern data analytics, enable unprecedented exploration of complex biological and environmental samples with significantly improved specificity, sensitivity, and resolution. Because of the merits of being high-resolution, label-free, non-invasive, molecular-specific, culture-independent, and suitable for in situ, in vitro or in vivo analysis, the SCRS-derived techniques offer abilities superior to conventional bulk measurements for environmental and biological studies. Here, we provide a comprehensive and critical review of the most recent advances in the development and application of SCRS-enabled technologies, with focus on those biomolecular and cellular high-resolution applications in environmental and biological fields. The basic principles, unique advantages, and suitable applications, as well as recognized limitations for each technology are recapitulated. The remaining challenges, research needs and future outlook are discussed. We predict that SCRS-enabled technologies are earning its place as a routine and powerful tool in many and rapidly expanding applications across disciplines.Wang, F.C.-Y., 2020. Comprehensive two-dimensional gas chromatography hyphenated with a vacuum ultraviolet spectrometer to analyze diesel—a three-dimensional separation (GC × GC × VUV) approach. Energy & Fuels 34, 8012-8017. separation of individual components continues to pose the greatest challenge in the characterization of complex hydrocarbon mixtures. Recent research has tackled this problem using several different multidimensional separation techniques such as coupling gas chromatography to a vacuum ultraviolet (VUV) spectrometer. Total absorption signals from the VUV spectrometer allow for general-purpose detection that is well suited for quantitative analysis. Full-range VUV spectra also can be collected that provide additional chemical information with absorption bands correlating to specific structural groups. When hyphenated with an advanced gas chromatography separation technique such as GC × GC, the full-range VUV spectrum can be used as a third dimension of separation. In this study, the three-dimensional technique, namely, comprehensive two-dimensional gas chromatography hyphenated with a vacuum ultraviolet spectrometer (GC × GC × VUV), is demonstrated using a diesel sample. The separation of various compounds that chromatographically coelute and the resolution of isomers that cannot be separated by mass spectrometry or any other analytical technique illustrate the power of this new analytical capability.Wang, H., Tian, L., Gu, D., Li, M., Chai, X., Yang, Y., 2020. Method for calculating non-Darcy flow permeability in tight oil reservoir. Transport in Porous Media 133, 357-372. force and boundary layer effect are the main causes of non-Darcy flow in tight oil reservoir. This paper proposes a non-Darcy flow dynamics characterization method for low-speed water flooding in tight oil reservoirs. It applies constant-speed mercury injection and casting thin section experiments to quantitatively characterize the micro-pore throat structure parameters, and uses the visual experimental device to measure the boundary layer thickness and fit the expression of the relationship between boundary layer thickness and displacement pressure gradient and fluid viscosity. The results show that the ratio of boundary layer thickness to microtubule radius changes exponentially with the pressure gradient and fluid viscosity and that the boundary layer thickness decreases gradually with the increase of pressure gradient. Given the capillary force and boundary layer thickness, the flow rate of single capillary is calculated. On this basis, the equation of nonlinear seepage dynamic characteristics per unit area of core is derived by taking into account the throat distribution frequency and throat size characteristics. The new seepage flow model can reflect the nonlinear seepage flow law of tight oil reservoir and provide reference for parameter formulation during water flooding development of tight oil reservoir.Wang, L., Gu, L.-j., Lu, H.-l., 2020. Sediment permeability change on natural gas hydrate dissociation induced by depressurization. China Geology 3, 221-229. The permeability of a natural gas hydrate reservoir is a critical parameter associated with gas hydrate production. Upon producing gas from a hydrate reservoir via depressurization, the permeability of sediments changes in two ways with hydrate dissociation, increasing with more pore space released from hydrate and decreasing due to pore compression by stronger effective stress related to depressurization. In order to study the evolution of sediment permeability during the production process with the depressurization method, an improved pore network model (PNM) method is developed to establish the permeability change model. In this model, permeability change induced by hydrate dissociation is investigated under hydrate occurrence morphology of pore filling and grain coating. The results obtained show that hydrate occurrence in sediment pore is with significant influence on permeability change. Within a reasonable degree of pore compression in field trial, the effect of pore space release on the reservoir permeability is greater than that of pore compression. The permeability of hydrate containing sediments keeps increasing in the course of gas production, no matter with what hydrate occurrence in sediment pore.Wang, M., Chen, D., Xiao, M., Ye, Q., Stolzenburg, D., Hofbauer, V., Ye, P., Vogel, A.L., Mauldin, R.L., Amorim, A., Baccarini, A., Baumgartner, B., Brilke, S., Dada, L., Dias, A., Duplissy, J., Finkenzeller, H., Garmash, O., He, X.-C., Hoyle, C.R., Kim, C., Kvashnin, A., Lehtipalo, K., Fischer, L., Molteni, U., Pet?j?, T., Pospisilova, V., Quéléver, L.L.J., Rissanen, M., Simon, M., Tauber, C., Tomé, A., Wagner, A.C., Weitz, L., Volkamer, R., Winkler, P.M., Kirkby, J., Worsnop, D.R., Kulmala, M., Baltensperger, U., Dommen, J., El-Haddad, I., Donahue, N.M., 2020h. Photo-oxidation of aromatic hydrocarbons produces low-volatility organic compounds. Environmental Science & Technology 54, 7911-7921. better understand the role of aromatic hydrocarbons in new-particle formation, we measured the particle-phase abundance and volatility of oxidation products following the reaction of aromatic hydrocarbons with OH radicals. For this we used thermal desorption in an iodide-adduct Time-of-Flight Chemical-Ionization Mass Spectrometer equipped with a Filter Inlet for Gases and AEROsols (FIGAERO-ToF-CIMS). The particle-phase volatility measurements confirm that oxidation products of toluene and naphthalene can contribute to the initial growth of newly formed particles. Toluene-derived (C7) oxidation products have a similar volatility distribution to that of α-pinene-derived (C10) oxidation products, while naphthalene-derived (C10) oxidation products are much less volatile than those from toluene or α-pinene; they are thus stronger contributors to growth. Rapid progression through multiple generations of oxidation is more pronounced in toluene and naphthalene than in α-pinene, resulting in more oxidation but also favoring functional groups with much lower volatility per added oxygen atom, such as hydroxyl and carboxylic groups instead of hydroperoxide groups. Under conditions typical of polluted urban settings, naphthalene may well contribute to nucleation and the growth of the smallest particles, whereas the more abundant alkyl benzenes may overtake naphthalene once the particles have grown beyond the point where the Kelvin effect strongly influences the condensation driving force.Wang, N., Li, M., Tian, X., Hong, H., Wen, L., Wang, W., 2020. Climate-ocean control on the depositional watermass conditions and organic matter enrichment in Lower Cambrian black shale in the upper Yangtze Platform. Marine and Petroleum Geology 120, 104570. lower Cambrian sediments including the Qiongzhusi and Maidiping formations in the Sichuan Basin are generally considered as the main source rocks of Precambrian-Cambrian petroleum system. A comprehensive study integrated with multiple geochemical methods was conducted on 119 lower Cambrian drillcore samples collected from the upper Yangtze Platform. The results show that the fluctuation of sea level and climate during the deposition of the Qiongzhusi and Maidiping formations act as the critical factors controlling the watermass conditions and thus OM accumulation. During the deposition of upper Maidiping Formation (?1m), the paleoclimate was arid and sea level was relatively low in the study area. The depositional environment indexes (UEF-MoEF, gammacerane index, β-carotane and VEF) suggested that the upper ?1m was deposited in a strong restricted marine setting with high water salinity and anoxic water conditions in Ziyang-Weiyuan area. However, during the early Qiongzhusi Formation period, the paleoclimate became humid and sea level rose in the study area. High paleoproductiviy caused by high concentrations of nutrients brought by seawater and freshwater plays an important role in OM accumulation in the basal part of the Qiongzhusi Formation (?1q). Furthermore, the model of paleoproductivity promotion caused by the coordinated control of climate and extensive transgression in the lower part of ?1q may also be applicable to interpret the origin of high organic carbon abundance in the strata deposited in the same period with the ?1q (such as Shiyantou, Shuijingtuo and Niutitang formations) in other parts of the upper Yangtze Platform.Wang, S., Newland, M.J., Deng, W., Rickard, A.R., Hamilton, J.F., Mu?oz, A., Ródenas, M., Vázquez, M.M., Wang, L., Wang, X., 2020. Aromatic photo-oxidation, a new source of atmospheric acidity. Environmental Science & Technology 54, 7798-7806. acid (HCOOH), one of the most important and ubiquitous organic acids in the Earth’s atmosphere, contributes substantially to atmospheric acidity and affects pH-dependent reactions in the aqueous phase. However, based on the current mechanistic understanding, even the most advanced chemical models significantly underestimate the HCOOH concentrations when compared to ambient observations at both ground-level and high altitude, thus underrating its atmospheric impact. Here we reveal new chemical pathways to HCOOH formation from reactions of both O3 and OH with ketene-enols, which are important and to date undiscovered intermediates produced in the photo-oxidation of aromatics and furans. We highlight that the estimated yields of HCOOH from ketene-enol oxidation are up to 60% in polluted urban areas and greater than 30% even in the continental background. Our theoretical calculations are further supported by a chamber experiment evaluation. Considering that aromatic compounds are highly reactive and contribute ca. 10% to global nonmethane hydrocarbon emissions and 20% in urban areas, the new oxidation pathways presented here should help to narrow the budget gap of HCOOH and other small organic acids and can be relevant in any environment with high aromatic emissions, including urban areas and biomass burning plumes.Wang, S., Yang, Y., Zhu, Z., Jin, L., Ou, S., 2020. Riverine deposition pattern of oil–particle aggregates considering the coagulation effect. Science of The Total Environment 739, 140371. understand the heterogeneous behavior of oil–particle aggregates (OPAs) in the riverine environment as well as the uncertainties caused by the coupling effects between their stochastic formation and transportation processes, this study employed the coagulation conceptual formula and random-walk particle tracking model. Through careful inspection using the classic Rouse–Vanoni diagram and existing laboratory observations, a vertical diffusivity scheme and the packing coefficient for an oil–sediment interaction model were determined. The density variations and deposition patterns of hypothetically fully developed OPAs as well as the impact of oil–sediment interactions on the longitudinal distribution of deposited OPAs were then investigated. The results indicate that the formation process of OPAs has a significant effect on their longitudinal deposition. The range of potentially trapped OPAs varied from several to hundreds of times the range of cases that exclude oil–sediment interactions. The deposition diagram proposed in this study visualizes the relationship between the configuration and deposition pattern of OPAs and can assist in determining the most unfavorable scenarios for oil-spill countermeasures. Further refinement and calibration of the model are necessary in the future to provide guidelines for oil spill responses and recovery in riverine environments.Wang, W., Li, Z., Zeng, L., Dong, C., Shao, Z., 2020. The oxidation of hydrocarbons by diverse heterotrophic and mixotrophic bacteria that inhabit deep-sea hydrothermal ecosystems. The ISME Journal 14, 1994-2006. activity can generate numerous and diverse hydrocarbon compounds. However, little is known about the influence of such hydrocarbons on deep-sea hydrothermal microbial ecology. We hypothesize that certain bacteria live on these hydrocarbons. Therefore, in this study, the distribution of hydrocarbons and their associated hydrocarbon-degrading bacteria were investigated at deep-sea hydrothermal vents at the Southern Mid-Atlantic Ridge, the Southwest Indian Ridge, and the East Pacific Rise. A variety of hydrocarbon-degrading consortia were obtained from hydrothermal samples collected at the aforementioned sites after low-temperature enrichment under high hydrostatic pressures, and the bacteria responsible for the degradation of hydrocarbons were investigated by DNA-based stable-isotope probing with uniformly 13C-labeled hydrocarbons. Unusually, we identified several previously recognized sulfur-oxidizing chemoautotrophs as hydrocarbon-degrading bacteria, e.g., the SAR324 group, the SUP05 clade, and Sulfurimonas, and for the first time confirmed their ability to degrade hydrocarbons. In addition, Erythrobacter, Pusillimonas, and SAR202 clade were shown to degrade polycyclic aromatic hydrocarbons for the first time. These results together with relatively high abundance in situ of most of the above-described bacteria highlight the potential influence of hydrocarbons in configuring the vent microbial community, and have made the importance of mixotrophs in hydrothermal vent ecosystems evident.Wang, W., Liu, Y., Duan, F., Zhang, J., Liu, X., Reid, R.E.B., Zhang, M., Dong, W., Wang, Y., Ruan, Q., Li, W., An, C.-B., 2020. A comprehensive investigation of Bronze Age human dietary strategies from different altitudinal environments in the Inner Asian Mountain Corridor. Journal of Archaeological Science 121, 105201. early presence of crops from East Asia and Southwest Asia in the Inner Asian Mountain Corridor (IAMC) has drawn attention to the Bronze Age mountain archaeology of Central Asia. Namely, the Bronze Age diffusion and utilization of grains in this region remains unknown as contrasts and extremes characterize the territory in environmental terms, especially elevation. Researchers continue to reflect on how, during the second millennium BC, Bronze Age populations used new crops and local animal resources to adapt to different elevation environments of the IAMC. In this study, we analyzed the 41 latest stable carbon and nitrogen isotopic results from human and faunal bones from six Bronze Age sites in the IAMC, 261 previously published stable isotopic datasets, and 12 archaeobotanical and four zooarchaeological results to investigate the dietary strategies of populations from different elevation environments in the Bronze Age IAMC. The results show an altitudinal gradient in dietary choices among Bronze Age populations in the IAMC, with mixed C4 and C3 consumption at the low-mid elevations and notable C3 consumption at the high elevations. Archaeobotanical and faunal remains also support these isotopic results. Our study further highlights that the differentiated dietary strategies adopted by the Bronze Age population in IAMC may have been the product of adaptation to local geographic environments. Social interaction may have also played a role in certain types of special dietary consumption.Wang, X., Barrat, J.-A., Bayon, G., Chauvaud, l., Feng, D., 2020. Lanthanum anomalies as fingerprints of methanotrophy. Geochemical Perspectives Letters 14, 26-30. is an important greenhouse gas whose emissions into the oceans and atmosphere are regulated by relatively unconstrained anaerobic and aerobic microbial processes. The aerobic pathway for methane oxidation is thought to be largely dependent upon the use of rare earth elements (REE), but to date the effects of this process on their abundances in bacteria or in organisms living in symbiosis with methanotrophs remain to be evaluated. Here we show that deep sea chemosynthetic mussels prospering at methane seeps display distinctive lanthanum enrichments linked to the enzymatic activities of their symbionts. These results demonstrate that methanotrophy is able to fractionate efficiently REE distributions in organisms and possibly in the environment. Lanthanum anomalies recorded in ancient sediments are potential chemical fossils that could be used in the geological record for tracking early evidence of microbial life. Wang, X., Zhu, Y., Song, Y., Mathews, J.P., 2020. Structure and partial ordering of terrestrial kerogen: Insight from high-resolution transmission electron microscopy. Fuel 281, 118759. structure impacts shale gas behavior: adsorption, desorption, and diffusion. The structural partial order (the orientation and stacking extent) varies with source and maturation. The partial order of eight terrestrial kerogen samples were evaluated using high-resolution transmission electron microscopy. The fringe length, angle, and stacking distributions were quantified. For the majority of the vitrinite equivalent reflectance (VReq) range (1.1–1.9%), the aromatic structural units were similar in distribution: mainly composed of fringes of size equivalent to naphthalene, 2 × 2, and 3 × 3 rings. When the VReq was > 1.7%, there was a shift in the distribution towards the larger molecules and some fringes equivalent to 4 × 4 ring structures were present. A slight orientation was found in the sample having the lowest VReq value, with greater alignment in the VReq range 1.5–1.9% There was significantly higher alignment for the overmature samples. Stacking was limited with 92 to 99% of fringes being an individual “layer”. There was an increase in the stacking frequency with an increase of VReq > 1.8% with some stacks exceeding four layers. Thus, the increase in the structural order for the basic structural units was not uniform with maturation. There was a continuous but slight change in partial order when the reflectance was between 1.1 and 1.7% but a transition when the reflectance was ~1.8–2.0%. The transition in partial ordering from slight to more ordered was consistent with coalification jump transitions for coal maturation at Ro,m = 1.8–2.0%. These transformations are likely to impact the shale gas adsorption and its behaviors.Wang, Y., Jiang, H., Ke, Y., Zhang, S., Wang, L., Wang, Y., He, C., Zhang, L., Wang, J.-Q., 2020. Investigation of pore structures in shallow Longmaxi shale, South China, via large-area electron imaging and neutron scattering techniques. Energy & Fuels 34, 7974-7984. structures are significant for evaluating shale gas production since they not only control gas capacity but also affect hydraulic fracturing. In this study, we investigated the pore structures of Longmaxi (LMX) shale samples from a shallow drill core in Guizhou Province, China, with large-area electron imaging and neutron scattering. Pores related to the mineral matrix and organic matter (OM) were identified, and the former had greater impacts on the pore shape and porosity, which would enhance fracturing. Large-area electron imaging analysis (with 15 nm resolution) indicated that the majority of LMX shale porosity was contributed by nanopores with diameters smaller than 400 nm. According to the neutron scattering data, micropores and mesopores dominated the pore size distribution (PSD), and pores within cross sections cut perpendicular to the bedding showed preferential orientation accompanied by larger porosity. The porosity (4.6–5.6%) calculated from neutron scattering data was approximately 2 times larger than that calculated from imaging data, suggesting that nanopores smaller than 15 nm contributed more to the porosity than those larger than 100 nm, as they were more resistant to compaction. This study indicated that pore types were controlled by minerals as well as thermal maturity, while PSDs were affected by tectonic movements. The majority of porosity originated from micropores and mesopores, which confirmed the great potential for shale gas reserves in the LMX shale. This conclusion is helpful for building a shale porosity model and eventually improving the reserve assessment.Wang, Y., Liu, D., Cai, Y., Yao, Y., Pan, Z., 2020. Constraining coalbed methane reservoir petrophysical and mechanical properties through a new coal structure index in the southern Qinshui Basin, northern China: Implications for hydraulic fracturing. American Association of Petroleum Geologists Bulletin 104, 1817-1842. deformed coal (SDC) influences not only gas outbursts during coal mining but also coalbed methane (CBM) production. Different SDCs have different mechanical strengths and physical properties. The structurally constrained petrophysical and mechanical properties of a CBM reservoir from the southern Qinshui Basin (SQB), northern China, have been investigated by using a coal structure index (CSI). The CSI was established as a quantitative criterion for the deformation of SDCs based on surface conditions and blockiness using the data of 783 coring samples from 109 CBM wells. The results show that undeformed coal and slight brittle SDCs are dominant in the SQB, with ductile SDCs distributed locally. Both compressive strength and tensile strength decline exponentially with increasing CSI average (avg.). Coal structure is a crucial factor for coal seam fracturing; with an increasing CSI (avg.), the major fracture length will first increase to the maximum of 266 m at a CSI (avg.) of 45 and then decrease rapidly. However, branch fractures are independent of the CSI (avg.). The major fracture height attained a minimum of 4.39 m at a CSI (avg.) of 40 and then slowly increased. Therefore, slightly brittle SDCs should be beneficial for fracturing, at least for high-rank coals. The presence of variable SDCs can have a considerable impact on CBM reservoir petrophysical and mechanical properties. Finally, a CSI model that strives to establish the relation between structure deformation and CBM reservoir physical and mechanical properties in coal is expected to effectively guide hydraulic fracturing.Wang, Z., Dilmore, R.M., Harbert, W., 2020. Inferring CO2 saturation from synthetic surface seismic and downhole monitoring data using machine learning for leakage detection at CO2 sequestration sites. International Journal of Greenhouse Gas Control 100, 103115. CO2 saturation from seismic data is important when seismic methods are applied at CO2 sequestration sites for verification and accounting purposes, such as verifying the total injected CO2 volume, comparing with model predictions for concordance evaluation, tracking the migration of CO2 plume, and detecting possible leakage from the storage reservoir. In this work, we infer CO2 saturation levels at three depths from simulated surface seismic, downhole pressure and total dissolved solids (TDS) data using machine learning (ML) methods. The simulated monitoring data are based on 6000 numerical multi-phase flow simulations of hypothetical wellbore CO2 and brine leakage from a legacy well into shallow aquifers at a model CO2 storage site. We conduct rock physics modeling to estimate changes in seismic velocity due to the simulated CO2 and brine leakage at each time step in the flow simulation outputs, resulting in 120,000 forward seismic velocity models. 2D finite-difference acoustic wave modeling is performed for each velocity model to generate synthetic shot gathers, along a sparse 2D seismic line with only 5 shots and 40 receivers. We extract 6 time-lapse seismic attribute anomalies from each trace in the time window relevant to each geologic layer, and use the seismic features, together with downhole pore pressure, TDS features to train the machine learning algorithms. The impact of seismic noise on the performance of the trained machine learning models has also been investigated. Inferred CO2 saturations from the trained classifiers are in good agreement with observations. Direct pressure and TDS measurements from downhole monitoring can increase the accuracy of the inferred CO2 saturation class from the forward modeled 2D surface seismic data. Our ML workflow represents a promising way to combine measurements from multiple monitoring techniques, together with seismic monitoring to achieve more accurate seismic quantitative interpretation.Wang, Z., Tang, Y., Wang, Y., Zheng, Y., Chen, F., Wu, S., Fu, D., 2020. Kinetics of shale oil generation from kerogen in saline basin and its exploration significance: An example from the Eocene Qianjiang Formation, Jianghan Basin, China. Journal of Analytical and Applied Pyrolysis 150, 104885. this study, confined pyrolysis experiments were performed on kerogen from the Qianjiang Formation in the Jianghan Basin, China, to investigate hydrocarbon evolution in the inter-salt shale deposited in the basin. Kinetic parameters obtained from the pyrolysis experiments were applied to reconstruct the history of hydrocarbon generation in the Eq34–10 cyclothem inter-salt shale reservoir. The results indicate the following: (a) The source rock deposited in the salt basin has a high hydrocarbon potential and a low activation energy for hydrocarbon generation. Petroleum can be generated at a lower maturity stage, and the maximum yield is reached at an EasyRo% of approximately 0.75 %. (b) Hydrocarbon generation from the Eq34–10 cyclothem inter-salt shale reservoir started at approximately 36–33 Ma. The current conversion rates (total oil) for the shale are approximately 0.59, 0.97, 0.97, and 0.88 in wells designated A, B, C, and D, respectively. (c) Deeper shale oil characterized by a high proportion of saturated hydrocarbons migrated laterally and were concentrated in the anticlinal area with shallow burial depth. In regions where structural traps form, lateral up-dip oil migration along variably deformed shallow shale laminates are conducive to the formation of shale oil systems. In thermally mature source kitchens, continuous shale oil accumulation in structurally undisturbed areas still provides attractive shale oil drilling targets.Weatherbee, S.L., Brau, T., Stoll, D.R., Rutan, S.C., Collinson, M.M., 2020. Simulation of elution profiles in liquid chromatography – IV: Experimental characterization and modeling of solute injection profiles from a modulation valve used in two-dimensional liquid chromatography. Journal of Chromatography A 1626, 461373. software for liquid chromatography can accelerate method development capabilities. In two-dimensional chromatography this is particularly attractive because there are more method variables to consider, provided simulations can account for the effects of injecting effluent from the first dimension separation into the second dimension column. In this paper we describe the adaptation of a previously described model (the Forssén model) to enable prediction of the profile of an injection pulse as it exits an Active Solvent Modulation (ASM) valve and enters the second dimension column under a variety of flow rate and sample loop size conditions (a global model). Experimentally measured injection profiles were used to train empirical models capable of generating injection profiles as a function of sample loop volume and flow rate. The resulting parameters were then used to generate an injection profile for a loop volume not used in the training set. The resulting profile agreed well with the experimentally obtained profile for this sample loop. Finally, chromatograms were simulated using previously developed simulation software incorporating the injection profile models developed in this work. Chromatographic peaks were simulated for valerophenone on an Agilent Zorbax Stablebond C18 stationary phase with an acetonitrile/water mobile phase gradient. Results of simulations based on experimental injection profiles, profiles predicted using the Forssén or global models, and rectangular injection profiles were compared. Comparison of the resulting chromatographic peaks revealed good agreement between those produced using experimental profiles or the Forssén or global models, with less than ± 0.3% deviations for retention times and less than ± 10% deviations for the peak widths (expressed as σ).Wei, B., Mollenhauer, G., Hefter, J., Grotheer, H., Jia, G., 2020. Dispersal and aging of terrigenous organic matter in the Pearl River Estuary and the northern South China Sea Shelf. Geochimica et Cosmochimica Acta 282, 324-339. rivers discharge great amounts of terrigenous organic carbon (OCterr) to the ocean, 90% of which are trapped in the coastal areas. The OCterr processing during transport to and within the coastal oceans are not well known. The Pearl River is the second largest river in China in terms of annual runoff. Here, we studied OCterr delivered from the river in the Pearl River Estuary (PRE) and the northern South China Sea (SCS) shelf using stable and radioactive carbon isotope compositions (δ13C and F14C) of OC in surface sediments to (1) constrain sources of OC, (2) explore the role of hydrodynamic processes for OCterr transport, and (3) better understand the burial and degradation processes of OCterr.A three end-member mixing model based on δ13C and 1/(C/N) values of bulk OC was used to calculate relative contributions of OCterr, OC derived from marine (OCmar) and riverine primary production (OCRpp). Results showed that the PRE and its western coastal inshore mud deposit are dominated by OCterr (70?±?3% and 54?±?10%, respectively), but other areas receive increasing contributions from OCmar: the slope (49?±?10%), the eastern coast (58?±?2%) and the outer shelf (68?±?3%). OCRpp accounted for substantial proportions in the PRE (14?±?6%) and rapidly decreased in the offshore area (3–5%), likely due to extensive aerobic respiration of organic matter (OM). Subsequently, average F14C values of OCterr were calculated ranging from 0.271 to 0.639 using a Monte-Carlo simulation strategy and based on the assumption that F14C values of OCRpp and OCmar varied within narrow ranges. Together with OCterr contents and grain sizes of sediments, F14C values of OCterr were used to distinguish two regions of distinctive sedimentological characteristics in the study area. Region I, including the PRE and inner shelf, showed a decrease of OCterr content along the trajectory of westward along-shelf transport, reflecting resuspension-dominated conditions for OCterr transport. Region II, including the outer shelf and one site on the inner shelf (E701), exhibited relatively old OCterr (9180?±?730?yr BP), which is attributed to preferential accumulation of coarser sediments by bedload movement. Finally, a first-order degradation rate constant was calculated from contents and 14C ages of OCterr, yielding a slow OCterr degradation rate of (2.88?±?0.61)?×?10–4 yr?1, indicating a more refractory nature and likely effective mineral protection of OCterr. The ΣCO2 efflux due to OCterr degradation was estimated to be 3.68?±?1.39 Gg C yr?1 for the entire surface sediments in the Pearl River derived mud belt, equivalent to only 0.7?±?0.3% of the total particulate OC flux of the Pearl River. This, hence, suggests that the OCterr is more persistent and the preservation of OCterr in the marine system is better than previously thought, but experiences substantial degradation on centennial to millennial timescales.Weller, Z.D., Hamburg, S.P., von Fischer, J.C., 2020. A national estimate of methane leakage from pipeline mains in natural gas local distribution systems. Environmental Science & Technology 54, 8958-8967. estimate methane emissions from U.S. local distribution natural gas (NG) pipes using data collected from an advanced mobile leak detection (AMLD) platform. We estimate that there are 630,000 leaks in U.S. distribution mains, resulting in methane emissions of 0.69 Tg/year (95% cr int: 0.25, 1.23). Total emissions are calculated as the product of activity factors and emissions factors. Our analysis leveraged data on >4000 leak indications found using AMLD, combined with utility pipeline GIS information, to allow us to estimate activity factors. We derive emissions factors from AMLD emission rate estimates and correct these emissions factors based on data from in-field studies assessing AMLD emissions estimates. Finally, we quantify uncertainty in both emissions factors and activity factors and propagate the uncertainty to our total emissions estimate. In modeling leak frequency, we find a clear interaction between pipeline material and age with the leakiness of all material types increasing with age. Our national methane emissions estimate is approximately 5× greater (95% cr int: 1.7×, 8.7×) than the U.S. Environmental Protection Agency’s current greenhouse gas inventory estimate for pipeline mains in local distribution systems due to both a larger estimated number of leaks and better characterization of the upper tail of the skewed distribution of emission rates.Wells, M., Kanmanii, N.J., Al Zadjali, A.M., Janecka, J.E., Basu, P., Oremland, R.S., Stolz, J.F., 2020. Methane, arsenic, selenium and the origins of the DMSO reductase family. Scientific Reports 10, 10946. molybdoenzymes of the dimethyl sulfoxide reductase (DMSOR) family catalyze a number of reactions essential to the carbon, nitrogen, sulfur, arsenic, and selenium biogeochemical cycles. These enzymes are also ancient, with many lineages likely predating the divergence of the last universal common ancestor into the Bacteria and Archaea domains. We have constructed rooted phylogenies for over 1,550 representatives of the DMSOR family using maximum likelihood methods to investigate the evolution of the arsenic biogeochemical cycle. The phylogenetic analysis provides compelling evidence that formylmethanofuran dehydrogenase B subunits, which catalyze the reduction of CO2 to formate during hydrogenotrophic methanogenesis, constitutes the most ancient lineage. Our analysis also provides robust support for selenocysteine as the ancestral ligand for the Mo/W atom. Finally, we demonstrate that anaerobic arsenite oxidase and respiratory arsenate reductase catalytic subunits represent a more ancient lineage of DMSORs compared to aerobic arsenite oxidase catalytic subunits, which evolved from the assimilatory nitrate reductase lineage. This provides substantial support for an active arsenic biogeochemical cycle on the anoxic Archean Earth. Our work emphasizes that the use of chalcophilic elements as substrates as well as the Mo/W ligand in DMSORs has indelibly shaped the diversification of these enzymes through deep time.Wester-Larsen, L., Kramsh?j, M., Albers, C.N., Rinnan, R., 2020. Biogenic volatile organic compounds in Arctic soil: A field study of concentrations and variability with vegetation cover. Journal of Geophysical Research: Biogeosciences 125, e2019JG005551. biogenic volatile organic compounds (sBVOCs) contribute to ecosystem emissions and play an important role in the soil ecosystem. Most previous studies on sBVOCs have looked at emissions from excavated soil in the laboratory or in situ emissions from areas with bare soil, using chambers. So far, however, the actual BVOC concentrations in the soil have rarely been considered. Herein, we sought to explore the relationships between the vegetation cover in a low Arctic heath ecosystem in Western Greenland and the BVOC concentration in the soil below. In situ measurements were performed at 15‐cm depth in areas dominated by Cassiope tetragona , Empetrum nigrum , Salix glauca , and Betula nana and along a 36‐m‐long transect with mixed vegetation cover during the growing seasons of 2015–2017. sBVOC concentrations varied between the different vegetation covers, with higher concentrations below Cassiope and Betula compared to Empetrum . Furthermore, sBVOC concentrations differed along the transect, and this variation was also partly related to differences in the vegetation cover. Moreover, we demonstrate that installation of a soil probe, for sampling soil air, changes the composition and magnitude of sBVOCs up to 1 day after the installation.Weyrauch, P., Heker, I., Zaytsev, A.V., von Hagen, C.A., Arnold, M.E., Golding, B.T., Meckenstock, R.U., 2020. The 5,6,7,8-tetrahydro-2-naphthoyl-coenzyme a reductase reaction in the anaerobic degradation of naphthalene and identification of downstream metabolites. Applied and Environmental Microbiology 86, e00996-20.: Anaerobic degradation of polycyclic aromatic hydrocarbons has been investigated mostly with naphthalene as a model compound. Naphthalene degradation by sulfate-reducing bacteria proceeds via carboxylation to 2-naphthoic acid, formation of a coenzyme A thioester, and subsequent reduction to 5,6,7,8-tetrahydro-2-naphthoyl-coenzyme A (THNCoA), which is further reduced to hexahydro-2-naphthoyl-CoA (HHNCoA) by tetrahydronaphthoyl-CoA reductase (THNCoA reductase), an enzyme similar to class I benzoyl-CoA reductases. When analyzing THNCoA reductase assays with crude cell extracts and NADH as electron donor via liquid chromatography-mass spectrometry (LC-MS), scanning for putative metabolites, we found that small amounts of the product of an HHNCoA hydratase were formed in the assays, but the downstream conversion by an NAD+-dependent β-hydroxyacyl-CoA dehydrogenase was prevented by the excess of NADH in those assays. Experiments with alternative electron donors indicated that 2-oxoglutarate can serve as an indirect electron donor for the THNCoA-reducing system via a 2-oxoglutarate:ferredoxin oxidoreductase. With 2-oxoglutarate as electron donor, THNCoA was completely converted and further metabolites resulting from subsequent β-oxidation-like reactions and hydrolytic ring cleavage were detected. These metabolites indicate a downstream pathway with water addition to HHNCoA and ring fission via a hydrolase acting on a β’-hydroxy-β-oxo-decahydro-2-naphthoyl-CoA intermediate. Formation of the downstream intermediate cis-2-carboxycyclohexylacetyl-CoA, which is the substrate for the previously described lower degradation pathway leading to the central metabolism, completes the anaerobic degradation pathway of naphthalene.Importance: Anaerobic degradation of polycyclic aromatic hydrocarbons is poorly investigated despite its significance in anoxic sediments. Using alternative electron donors for the 5,6,7,8-tetrahydro-2-naphthoyl-CoA reductase reaction, we observed intermediary metabolites of anaerobic naphthalene degradation via in vitro enzyme assays with cell extracts of anaerobic naphthalene degraders. The identified metabolites provide evidence that ring reduction terminates at the stage of hexahydro-2-naphthoyl-CoA and a sequence of β-oxidation-like degradation reactions starts with a hydratase acting on this intermediate. The final product of this reaction sequence was identified as cis-2-carboxycyclohexylacetyl-CoA, a compound for which a further downstream degradation pathway has recently been published (P. Weyrauch, A. V. Zaytsev, S. Stephan, L. Kocks, et al., Environ Microbiol 19:2819–2830, 2017, ). Our study reveals the first ring-cleaving reaction in the anaerobic naphthalene degradation pathway. It closes the gap between the reduction of the first ring of 2-naphthoyl-CoA by 2-napthoyl-CoA reductase and the lower degradation pathway starting from cis-2-carboxycyclohexylacetyl-CoA, where the second ring cleavage takes place.Wicker, A.P., Tanaka, K., Nishimura, M., Chen, V., Ogura, T., Hedgepeth, W., Schug, K.A., 2020. Multivariate approach to on-line supercritical fluid extraction – supercritical fluid chromatography - mass spectrometry method development. Analytica Chimica Acta 1127, 282-294. supercritical fluid extraction (SFE) on-line with supercritical fluid chromatography (SFC) – tandem mass spectrometry (MS/MS) provides a single platform for efficient extraction, separation, and detection in a chemical analysis. SFE–SFC–MS/MS requires consideration of many extraction and chromatographic variables to not only provide the most efficient extraction, but also to analytically transfer the extracted analytes to the column for separation. There is a fundamental lack of understanding of how the variables in SFE affect those in SFC. Typically, a univariate approach is taken in on-line SFE–SFC–MS/MS method development, but this provides little insight into the relative importance of variables and their potential interactions. Here, a multivariate approach was used to develop a better understanding of the synergistic relationship between the extraction and separation processes by focusing on the optimization of extraction parameters for target analytes with a wide range of physicochemical properties in matrices of variable retentivity. The methodology used a set of optimal on-line SFE–SFC–MS/MS extraction parameters for 18 analytes of variable physicochemical properties in three different silica gel-based sample matrices are presented.Wiemann, J., Crawford, J.M., Briggs, D.E.G., 2020. Phylogenetic and physiological signals in metazoan fossil biomolecules. Science Advances 6, eaba6883., lipids, and sugars establish animal form and function. However, the preservation of biological signals in fossil organic matter is poorly understood. Here, we used high-resolution in situ Raman microspectroscopy to analyze the molecular compositions of 113 Phanerozoic metazoan fossils and sediments. Proteins, lipids, and sugars converge in composition during fossilization through lipoxidation and glycoxidation to form endogenous N-, O-, and S-heterocyclic polymers. Nonetheless, multivariate spectral analysis reveals molecular heterogeneities: The relative abundance of glycoxidation and lipoxidation products distinguishes different tissue types. Preserved chelating ligands are diagnostic of different modes of biomineralization. Amino acid–specific fossilization products retain phylogenetic information and capture higher-rank metazoan relationships. Molecular signals survive in deep time and provide a powerful tool for reconstructing the evolutionary history of animals.Wilczyński, J., Haynes, G., Sobczyk, ?., Svoboda, J., Roblí?ková, M., Wojtal, P., 2020. Friend or foe? Large canid remains from Pavlovian sites and their archaeozoological context. Journal of Anthropological Archaeology 59, 101197. this paper we discuss recent claims that dogs were first domesticated from wild wolves in the Middle Upper Paleolithic (MUP), about 27?ka BP. According to our data, we think the presence of large canids at the Pavlovian/MUP sites is a result of hunting specialization and not a sign of an early process of dog domestication. Our interpretation is supported by the following observations, whose implications we discuss: (1) Pavlovian faunal assemblages from seven sites in Moravia contain relatively high numbers of large canids; (2) gnaw-marking by large canids occurs with low frequency on the animal bones in these assemblages; (3) the bones of Pavlovian large canids in the sites often have cut marks from skinning, dismembering, and filleting. Whatever the reasons MUP people had for killing wolves, such as for food or for the skins, the effect would have reduced competition for prey between humans and wolves. The relatively high frequency of wolves at Pavlovian sites may have been a side effect of settlement aggregation and long-term occupations of sites, which could have attracted wolves to the settlements, and thus increased the need for humans to reduce their numbers.Williams, S., 2020. Ancient beads point to far-flung relationships in southern Africa. The Scientist 2020. you’re looking for an accessory that never goes out of fashion, you can probably do no better than ostrich eggshell beads. The oldest known examples of these tiny, Cheerio-like decorations, found in rock shelters in Tanzania, have been dated to around 50,000 years ago, while similar creations are still made by San hunter-gatherers in Southern Africa’s Kalahari Desert today.The beads are often the last of many incarnations of an ostrich egg, explains Brian Stewart, an archaeologist at the University of Michigan. After finding an egg, the San—presumably like ancient human ancestors—carefully drill a hole in it and drain the white and yolk to be eaten. Then they wash out the shell, which makes a handy water flask. When the canteen eventually breaks, people reduce the fragments down to a standard size, drill a hole in the middle of each, string them together, and then shape the fragments into rounded beads. The beads can then be strung together to make jewelry or sewn onto clothing for decoration. Ethnographers have found that the San often exchange the beads, sometimes with people who live 200 or more kilometers away, to help cement social connections.Ostrich eggshell beads have also been found in other parts of Africa and in north Asia, places where, in general, people no longer make and trade them. Many have been discovered in rock shelter sites in Lesotho, a small, mountainous country that lies far to the southeast of the Kalahari, completely surrounded by South Africa. These beads were found in archeological layers that range in age from a few hundred years old to tens of thousands of years old, according to work by Stewart and others. It’s not known whether ostriches lived in Lesotho at the time the beads were made, Stewart notes, but it’s unlikely they did. “They really shouldn’t be up there in terms of their ecological preferences,” he says. “And certainly they’re not up there today.” So archeologists have long wondered whether the beads were “brought in or exchanged in from other areas. But they were never able to really test that.”Stewart and his colleagues recently saw their chance to do such a test using strontium isotope analysis, which uses the ratio of strontium isotopes in a sample to trace organisms back to the geological environments where they originated. Lesotho is particularly well-suited to such an analysis because of its mountainous terrain surrounded by land that steadily decreases in elevation, with different types of rock—each with its own strontium ratio—dominating the surface at different levels. Because the ratios of strontium isotopes in eggshell and other animal remains reflect those of the rock and soil where they originated, researchers would be able to use this method to pinpoint where the beads came from.There was a logistical hurdle the researchers would need to overcome, however: the group would need a large set of biological reference samples from multiple locations to create a strontium isotope map against which to compare the beads’ ratios. Assembling such a collection seemed like a Herculean task, but mulling over the problem, Stewart realized that such a collection already existed, albeit scattered across the back rooms of small natural history museums around South Africa. “They have these nice collections of small mammals . . . and they know exactly where they were taken from,” he says. “And, because they’re small mammals, they actually live in quite small, circumscribed territories.” Comparing the isotope ratios from the animals’ teeth with those of eggshell beads from two Lesotho rock shelters, the group found that none had strontium signatures that matched the local geological strata, confirming that the beads didn’t come from local eggshells. Instead, “pretty much all of them came from no closer than 100 kilometers away . . . and about 20 percent of the beads came from further than about 200 or 250 or so kilometers away,” Stewart says. Of those, a smaller subset came from at least 300 kilometers away—but possibly much more, he adds. Determining the provenance of that well-traveled subset will require more work.The oldest bead the team analyzed dates to about 33,000 years ago, and it happens to belong to the farthest-away subset. Combined with the climatic differences between verdant Lesotho and drylands to the west, and with what’s known about how the eggshell beads are exchanged today, the study’s results suggest the beads factored into savvy relationship-building, Stewart says. They “probably represent risk-hedging bets, or network[ing] attempts . . . on the part of desert hunter-gatherers who are trying to make . . . links with people that live up in the mountains where you’ve got more stable supplies of fresh water [and] of animals,” he says. How the beads physically got there is another question. One possibility, Stewart says, is that they traveled through a series of exchanges among desert groups who lived tens of kilometers apart. Ancient as some of them are, Lesotho’s ostrich beads are likely part of an older tradition of far-flung groups using goods to build social networks, perhaps as a way to ensure that they would receive help in tough times. “I think that gift exchange . . . is likely to have a much earlier origin,” Lyn Wadley, an archaeologist at the University of the Witwatersrand in Johannesburg, who was not involved in the study, writes in an email to The Scientist. Before ostrich shell beads came into fashion, “it may have operated through, for example, the early exchange of decorated eggshell flasks and marine shell beads.” Likewise, Stewart suspects that the small, uniform, mass-producible beads weren’t part of the first networking attempts, but represent “the end result of a longer process of evolution and becoming really flexible to difficult environments.” While Wadley thinks the isotope evidence the authors present for the beads’ far-flung origins is compelling, she adds that the results don’t rule out an alternative explanation: that, rather than being gifted, the beads were brought to Lesotho during long-distance seasonal migrations.Steven Kuhn, an anthropologist at the University of Arizona who was not involved in the research, also thinks it’s possible that the beads were transported long distances as personal possessions rather than gifts. But the authors’ explanation seems more plausible in light of what’s known about modern hunter-gatherers, he adds. Anthropologists have suspected that Homo sapiens long used a relationship-building strategy like the one laid out in the study to boost their chances of survival, he says.Eggshell beads are compelling evidence for gift exchange, he notes, because they would have been easy for people to make locally if desired—even Lesotho residents probably wouldn’t have had to travel far to gather ostrich eggs from nearby deserts—so there was no other practical reason to exchange them with people from far away. He compares the behavior to today’s custom of businesses giving away calendars, pens, or fruit baskets. “Nobody really needs another calendar,” he says. “It’s more about establishing a relationship.” Windirsch, T., Grosse, G., Ulrich, M., Schirrmeister, L., Fedorov, A.N., Konstantinov, P.Y., Fuchs, M., Jongejans, L.L., Wolter, J., Opel, T., Strauss, J., 2020. Organic carbon characteristics in ice-rich permafrost in Alas and Yedoma deposits, central Yakutia, Siberia. Biogeosciences 17, 3797-3814. ground is one of the largest repositories of terrestrial organic carbon and might become or already is a carbon source in response to ongoing global warming. With this study of syngenetically frozen, ice-rich and organic carbon (OC)-bearing Yedoma and associated alas deposits in central Yakutia (Republic of Sakha), we aimed to assess the local sediment deposition regime and its impact on permafrost carbon storage. For this purpose, we investigated the Yukechi alas area (61.76495°?N, 130.46664°?E), which is a thermokarst landscape degrading into Yedoma in central Yakutia. We retrieved two sediment cores (Yedoma upland, 22.35?m deep, and alas basin, 19.80?m deep) in 2015 and analyzed the biogeochemistry, sedimentology, radiocarbon dates and stable isotope geochemistry. The laboratory analyses of both cores revealed very low total OC (TOC) contents (<0.1?wt?%) for a 12?m section in each core, whereas the remaining sections ranged from 0.1?wt?% to 2.4?wt?% TOC. The core sections holding very little to no detectable OC consisted of coarser sandy material were estimated to be between 39?000 and 18?000?BP (years before present) in age. For this period, we assume the deposition of organic-poor material. Pore water stable isotope data from the Yedoma core indicated a continuously frozen state except for the surface sample, thereby ruling out Holocene reworking. In consequence, we see evidence that no strong organic matter (OM) decomposition took place in the sediments of the Yedoma core until today. The alas core from an adjacent thermokarst basin was strongly disturbed by lake development and permafrost thaw. Similar to the Yedoma core, some sections of the alas core were also OC poor (<0.1?wt?%) in 17 out of 28 samples. The Yedoma deposition was likely influenced by fluvial regimes in nearby streams and the Lena River shifting with climate. With its coarse sediments with low OC content (OC mean of 5.27?kg?m?3), the Yedoma deposits in the Yukechi area differ from other Yedoma sites in North Yakutia that were generally characterized by silty sediments with higher OC contents (OC mean of 19?kg?m?3 for the non-ice wedge sediment). Therefore, we conclude that sedimentary composition and deposition regimes of Yedoma may differ considerably within the Yedoma domain. The resulting heterogeneity should be taken into account for future upscaling approaches on the Yedoma carbon stock. The alas core, strongly affected by extensive thawing processes during the Holocene, indicates a possible future pathway of ground subsidence and further OC decomposition for thawing central Yakutian Yedoma deposits.Wolters, C., Flandinet, L., He, C., Isa, J., Orthous-Daunay, F.-R., Thissen, R., H?rst, S., Vuitton, V., 2020. Enhancing data acquisition for the analysis of complex organic matter in direct-infusion Orbitrap mass spectrometry using micro-scans. Rapid Communications in Mass Spectrometry 34, e8818.: Acquisition quality in analytical science is key to obtaining optimal data from a sample. In very high‐resolution mass spectrometry, quality is driven by the optimization of multiple parameters, including the use of scans and micro‐scans (or transients) for performing a Fourier transformation.Methods: Thirty‐nine mass spectra of a single synthesized complex sample were acquired using various numbers of scans and micro‐scans determined through a simple experimental design. An electrospray ionization source coupled with an LTQ Orbitrap XL? mass spectrometer was used, and acquisition was performed using a single mass range. All the resulting spectra were treated in the same way to enable comparisons of assigned stoichiometric formulae between acquisitions.Results: Converting the number of scans into micro‐scans enhances signal quality by lowering noise and reducing artifacts. This modification also increases the number of attributed stoichiometric formulae for an equivalent acquisition time, giving access to a larger molecular diversity for the analyzed complex sample.Conclusions: For complex samples, the use of long acquisition times leads to optimal data quality, and the use of micro‐scans instead of scans‐only maximizes the number of attributed stoichiometric formulae.Wong, S.L., Nyakuma, B.B., Wong, K.Y., Lee, C.T., Lee, T.H., Lee, C.H., 2020. Microplastics and nanoplastics in global food webs: A bibliometric analysis (2009–2019). Marine Pollution Bulletin 158, 111432. paper presents the research landscape on microplastics and nanoplastics (M/NPs) in global food webs based on a bibliometric analysis of 330 publications published in 2009–2019 extracted from Web of Science. The publications increased tremendously since 2013. Marine Pollution Bulletin is one of the top productive journals for this topic. The publication landscape related to M/NPs in global food webs, as interdisciplinary research, is highly dependent on the funding availability. The high productivities of England, China, USA and European countries are attributed to the funding from the agencies at regional or national levels. Keyword analysis reveals the shift of research hotspots from investigations on M/NPs absorbed by various organisms in the ecosystems to studies on the trophic transfer of M/NPs and sorbed contaminants in the food webs and their associated adverse impacts. Funding agencies play important roles in leading the future development of this topic.Wood, J.M., Haeri-Ardakani, O., Sanei, H., Curtis, M.E., Royer, D., 2020. Application of paleoporosity and bitumen saturation concepts to tight-gas accumulations containing solid bitumen. International Journal of Coal Geology 228, 103547. bitumen significantly influences reservoir quality in many unconventional tight and shale hydrocarbon accumulations. In the siltstone-dominated Montney Formation of northeast British Columbia and northwest Alberta organic matter is mostly in the form of solid bitumen and represents an original pore-filling oil phase that was later thermally cracked. Here, we show that the influence of solid bitumen on reservoir quality can be further understood by applying the concepts of paleoporosity and bitumen saturation. Paleoporosity is defined as the sum of present-day porosity and total organic carbon (TOC) volume, and conceptualized as the porosity available at the time of oil charging. Bitumen saturation is defined as TOC volume divided by paleoporosity, and conceptualized as the fraction of paleoporosity filled with oil/bitumen. We introduce the paleoporosity-bitumen saturation cross-plot and use it, together with organic petrography and scanning electron microscopy observations, to investigate how different combinations of paleoporosity and bitumen saturation impact rock properties. Solid bitumen in the Montney Formation influences pore throat size, porosity, permeability and wettability. Understanding such key rock properties benefits from recognizing paleoporosity and bitumen saturation as inherent rock attributes with wide-ranging combinations. The concepts of paleoporosity and bitumen saturation elucidated here can likely be applied to other tight hydrocarbon accumulations that contain organic matter dominantly in the form of solid bitumen.Wozniak, A.S., Goranov, A.I., Mitra, S., Bostick, K.W., Zimmerman, A.R., Schlesinger, D.R., Myneni, S., Hatcher, P.G., 2020. Molecular heterogeneity in pyrogenic dissolved organic matter from a thermal series of oak and grass chars. Organic Geochemistry 148, 104065. organic matter (Py-OM), generated via the incomplete combustion of biomass, is well studied due to the presence of slow-cycling, condensed aromatic compounds (ConAC) known to sequester in soils and sediments. Recently, dissolved Py-OM (Py-DOM) has received interest, due to its higher mobility and potential to be transferred through watersheds to aquatic systems. Py-DOM quantities, molecular identities and importance to global carbon budgets and cycles are only beginning to be understood. Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) analyses were performed on Py-DOM isolated from oak and grass biochars produced over a range of temperatures (250–650?°C), and the data are compared to complementary 1H NMR spectroscopic and benzenepolycarboxylic acid biomarker (BPCAs) analyses. Py-DOM is revealed to be a heterogeneous mixture of compounds ranging in relative aromaticity and oxygenation. FTICR-MS analyses demonstrate a decrease in Py-DOM relative oxygen content and a concurrent increase in aliphatic character and heteroatomic (N, Cl) content. 1H NMR and BPCAs analyses detail low O/C dissolved ConAC not observed by FTICR-MS, demonstrating the necessity for a multiple proxy approach to Py-DOM characterization. Heterogeneous Py-DOM is explained as resulting from pyrolysis-initiated and radical-mediated functional group cleavage, aromatic condensation and aromatic ring-opening reactions. Oak biomass progresses faster along a char maturity continuum for a given pyrolysis temperature, perhaps due to its greater lignin content or radical quenching by grass cuticular material. Biomass species and pyrolysis temperature likely result in different Py-DOM compositions and fates and must be considered when evaluating the impacts of wildfires and biochar applications.Wu, C., Yang, T., Shields, G.A., Bian, X., 2020. Termination of Cryogenian ironstone deposition by deep ocean euxinia. Geochemical Perspectives Letters 15, 1-5. deposition of iron-rich sedimentary rocks (ironstones) occurred during the Sturtian ice age, the earlier of two Cryogenian ‘Snowball Earth’ glaciations. However, the reasons for the termination of Cryogenian Iron Formation (CIF) deposition remain poorly understood. Here we report a multi-isotope (Fe-C-S) study of the Xinyu CIF in South China that can directly address this question. The isotopic compositions of these multivalent elements exhibit remarkable covariance at the top of the Xinyu CIF that reflects progressive redox stratification during iron oxide deposition. Iron oxide deposition ended abruptly due to the titration of ferrous iron as pyrite following a large influx of riverine sulfate. Although termination of CIF deposition is commonly attributed to oxygenation, our data show that at least in some Cryogenian ocean basins, CIF deposition ended with the spread of euxinic rather than oxygenated waters. Wu, F., Owens, J.D., Scholz, F., Huang, L., Li, S., Riedinger, N., Peterson, L.C., German, C.R., Nielsen, S.G., 2020. Sedimentary vanadium isotope signatures in low oxygen marine conditions. Geochimica et Cosmochimica Acta 284, 134-155. has been hypothesized that vanadium (V) isotopes have the potential to track sedimentary redox conditions due to multiple valence states occurring in nature, which might induce variable V isotope fractionation as a function of sedimentary redox state. These characteristica could make V isotopes a useful paleo-redox proxy. However, in order to understand the mechanisms driving V isotope fractionation, it is crucial to build a framework for the depositional and post-depositional controls on sedimentary V isotope records from a diverse set of sedimentary environments. This study, for the first time, investigates the V isotope variations of modern marine sediments deposited under a range of redox environments. Our results document that changes in local redox conditions impart a significant isotopic fractionation from seawater as recorded in the local sedimentary V isotopic signature. Importantly, there is a significant difference between the V isotope composition of sediments deposited in the open ocean setting with oxygen-deficient bottom waters compared to less reducing environments, whereby oxic sediments (benthic oxygen contents?>?10 μΜ) exhibit Δoxic?=??1.1?±?0.3‰ and anoxic sediments exhibit Δanoxic?=??0.7?±?0.2‰. Combined with previous studies on seawater particulate and sediment pore fluid analysis, our results indicate that V is mainly delivered and enriched in anoxic sediments through settling particulates. Authigenic V isotope compositions in marine sediments are likely controlled by isotope fractionation between V species bound to particulates and dissolved in seawater, which likely varies with the speciation and adsorption properties of V that are strongly controlled by local redox conditions. In addition, the euxinic Cariaco Basin sediments exhibit distinctive Δeuxinic?=??0.4?±?0.2‰, which is likely influenced by the relationship between the seawater V removal rate and the seawater renewal rate. Our results highlight the direct link between authigenic marine sedimentary V isotope compositions and the overlying local redox conditions. This investigation of V isotopes in modern marine environments provides an initial framework for the utilization of V isotopes to reconstruct ancient redox fluctuations, which has the potential to track subtle redox variations of local oxygen-deficient to low oxygen environments.Wu, W., Dijkstra, P., Dippold, M.A., 2020. 13C analysis of fatty acid fragments by gas chromatography mass spectrometry for metabolic flux analysis. Geochimica et Cosmochimica Acta 284, 92-106. multiple metabolic pathways lead to the same product, compound-specific isotope analysis may not provide enough information to quantify the activities of the contributing pathways. Instead, identification of where in the molecule the 13C is incorporated is required. Here we show how knowledge of position-specific 13C incorporation in fatty acids (FA) and FA fragments can be used to quantitatively estimate the fluxes through the central C metabolic network.We developed a method to measure 13C enrichment of FA and FA fragments (ethanoate, propionate) using electron impact GC–MS. We tested the accuracy and repeatability of the measurements using natural abundance and position-specific 13C labelled standards and FA extracted from Bacillus licheniformis and Pseudomonas fluorescens grown with labelled and unlabelled glucose. The molecular ions of FA generally reflected theoretical predictions of mass isotopomer distributions for natural abundance values, but that of the associated FA fragments deviated from expected values, likely associated with McLafferty rearrangements of hydrogen. After correction for naturally occurring isotopes, 13C enrichments of FA and FA fragments showed good agreement with expected isotope composition of FA standards (root mean square error?<?0.044 at%; δ13C of?～?40‰), natural abundance and labelled glucose. The unsaturated FA extracted from P. fluorescens deviated from expected values likely associated with problems of co-elution and ion suppression and were excluded from analysis.The ratio of glucose-1-13C to glucose-3-13C incorporation into FA fragments was high for B. licheniformis, but low for P. fluorescens. Metabolic flux modelling based on the 13C enrichment of ethanoate and propionate fragments showed that B. licheniformis used Embden-Meyerhof-Parnas and pentose phosphate pathway (66% and 30%, respectively), whereas P. fluorescens utilized Entner-Doudoroff and pentose phosphate pathway (72% and 27%, respectively). FA fragment analysis is therefore a promising tool to study central C metabolic network activities of co-occurring groups of microbes in intact and complex environmental communities.Wu, Y., Gao, S., Ji, B., Liu, Z., Zeng, X., Yu, Z., 2020. Occurrence of short- and medium-chain chlorinated paraffins in soils and sediments from Dongguan City, South China. Environmental Pollution 265, Part A, 114181. a group of emerging organic pollutants, chlorinated paraffins (CPs) have attracted rising global attention due to their persistence and toxicity. In this study, we have investigated the concentration levels and profiles of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in soils and sediments from Dongguan City, South China, and have also screened their transformation products by means of ultra-high-resolution mass spectrometry. The results indicated that total SCCP and MCCP concentrations ranged from 6.75 to 993?ng/g (mean 172?ng/g) and from 23.9 to 2426?ng/g (mean 369?ng/g) for soils, and from 4.00 to 613?ng/g (mean 153?ng/g) and from 14.0 to 1581?ng/g (mean 493?ng/g) for sediments, respectively. This suggested that MCCPs are the major CP components in China. The dominant congeners in soils and sediments were C13Cl6–7 and C14Cl7–8, C13Cl7, and C14Cl7–8, respectively. Furthermore, six new CP congeners (C8Cl7–8 and C9Cl5–8) in soils and four new CPs (C9Cl5–8) in sediments have been identified. Because of their higher detection frequencies, further studies should focus on the transformation mechanisms and toxicities of these new CPs in environmental media and biota.Wu, Y., Tahmasebi, P., Lin, C., Dong, C., 2020. A comprehensive investigation of the effects of organic-matter pores on shale properties: A multicomponent and multiscale modeling. Journal of Natural Gas Science and Engineering 81, 103425. (OM) pores play a significant role in the pore systems of shale formations. Numerous studies have analyzed the characteristics of OM pores. However, fewer studies reported the effects of OM pores on shale properties. In this study, a comprehensive pore-scale investigation of the impacts of OM pores on various physical properties of shale samples based on multicomponent and multiscale shale models is presented. To this end, a novel technique for constructing three-dimensional (3D), multicomponent, and multiscale shale models was proposed. Multiple shale models with different fractions of OM pores were then generated using the proposed algorithm. Based on these shale models, the effects of OM pores on the geometric properties, topological properties, correlation functions, and transport properties of pore space were comprehensively evaluated within the physics-based and realistic models. The results show that the addition of more OM pores in a pore system increases its connectivity, decreases its tortuosity, and strengthens the correlation of the voxels in the pore structure. At the same time, it enhances the surface roughness of the pore space, the proportions of small pores, and the number of isolated pores. Besides, the generation of more OM pores into the pore space leads to the increase of the permeability and decrease of the formation factor of the shale models.Wu, Z., Li, Q.P., Ge, Z., Huang, B., Dong, C., 2020. Impacts of biogenic polyunsaturated aldehydes on metabolism and community composition of particle-attached bacteria in coastal hypoxia. Biogeosciences Discussions 2020, 1-37. coastal hypoxia is of great interest recently, though its mechanisms are not fully understood. Here, we showed elevated concentrations of particulate and dissolved polyunsaturated aldehydes (PUAs) associated with the hypoxic waters meanly dominated by particle-attached bacteria (PAB) in the bottom water of a salt-wedge estuary. Particle-adsorbed PUAs of ~?10 micromoles per liter particle in the hypoxic waters were directly quantified for the first time using large-volume-filtration followed with on-site derivation and extraction of the adsorbed PUAs. PUAs-amended incubation experiments for PAB retrieved from the low-oxygen waters were also performed to explore the impacts of PUAs on the growth and metabolism of PAB and associated oxygen utilization. We found an increase in cell growth of PAB in response to low-dose PUAs (1?μmol?L?1) but an enhanced cell-specific metabolic activity in response to high-dose PUAs (100?μmol?L?1) including bacterial respiration and production. Improved cell-specific metabolism of PAB in response to high-dose PUAs was also accompanied by a significant shift of PAB community structure with increased dominance of genus Alteromonas within the Gammaproteobacteria. We thus conclude that a high PUAs concentration within the bottom layer may be important for species such as Alteromonas to regulate PAB community structure and lead to the enhancement of oxygen utilization during the degradation of particulate organic matters and thus contribute to the formation of coastal hypoxia. These findings are potentially important for coastal systems with large river inputs, intense phytoplankton blooms driven by eutrophication, as well as strong hypoxia developed below the salt-wedge front.Xia, T., Ren, H., Zhang, W., Xia, Y., 2020. Lipidome-wide characterization of phosphatidylinositols and phosphatidylglycerols on C=C location level. Analytica Chimica Acta 1128, 107-115. (PG) and phosphatidylinositol (PI) are two essential classes of glycerophospholipids (GPs), playing versatile roles such as signalling messengers and lipid-protein interaction ligands in cell. Although a majority of PG and PI molecular species contain unsaturated fatty acyl chain(s), conventional tandem mass spectrometry (MS/MS) methods cannot discern isomers different in carbon-carbon double bond (CC) locations. In this work, we paired phosphate methylation with acetone Paternò–Büchi (PB) reaction, aiming to provide a solution for sensitive and structurally informative analysis of these two important classes of GPs down to the location of C=C. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) workflow was established. Offline methylated PG or PI mixtures were subjected to hydrophilic interaction chromatographic separation, online acetone PB reaction, and MS/MS via collision-induced dissociation (CID) for C=C location determination in positive ion mode. This method was sensitive, offering limit of identification at 5?nM for both PG and PI standards down to C=C locations. On molecular species level, 49 PI and 31?PG were identified from bovine liver, while 61 PIs were identified from human plasma. This workflow also enabled ratiometric comparisons of C=C location isomers (C18:1 Δ9 vs. Δ11) of a series of PIs from type 2 diabetes (T2D) plasma to that of normal plasma samples. PI 16:0_18:1 and PI 18:0_18:1 were found to exhibit significant changes in C=C isomeric ratios between T2D and normal plasma samples. The above results demonstrate that the developed LC-PB-MS/MS workflow is applicable to different classes of lipids and compatible with other established lipid derivatization methods to achieve comprehensive lipid analysis.Xu, Y., Jia, Z., Xiao, W., Fang, J., Wang, Y., Luo, M., Wenzh?fer, F., Rowden, A.A., Glud, R.N., 2020. Glycerol dialkyl glycerol tetraethers in surface sediments from three Pacific trenches: Distribution, source and environmental implications. Organic Geochemistry 147, 104079. dialkyl glycerol tetraethers (GDGTs) have been widely used to elucidate sources of sediment total organic carbon (TOC), past temperature and presence of methanogenesis in diverse environments. However, their applicability to hadal trenches with their unique deposition dynamics remains unknown. Here, we analyzed GDGTs and their stable isotope values and content of TOC in surface sediments from the Kermadec Trench region (KT; 6080–10010?m), New Britain Trench region (NBT; 1553–8931?m), and Atacama Trench region (AT; 2560–8085?m). These regions are at very different distances from terrestrial sources and have varying net primary productivity (NPP) in the waters above them. The GDGT concentration was highly variable (54.5–2416?μg?g?1 TOC) within and between trench regions and was not directly related to local NPP or apparent terrestrial inputs. This finding is presumably due to complex deposition dynamics within the trench interior. Isoprenoidal GDGTs (isoGDGTs; 75.4–99.1%) were dominant over branched GDGTs (brGDGTs, 0.91–24.6%) in all samples, leading to low levels of Branched versus Isoprenoidal Tetraether (BIT) index (0.01–0.27). Thus, sediment TOC is mainly derived from marine sources. However, compared to adjacent non-hadal sites, trench axis sites have a higher BIT index, lower acyclic hexa-/pentamethylated brGDGT and lower δ13C, supporting relative enrichment of terrestrial organic carbon at the trench axis. The application of TetraEther indeX of tetraethers consisting of 86 carbon atoms (TEX86) resulted in sea surface temperature (SST) estimates of 18.9–23.7?°C in the KT, 28.6–30.2?°C in the NBT, and 17.9–20.4?°C in the AT. The close agreement between TEX86-SST with observed in situ SST suggests that isoGDGTs are not selectively degraded during the transport towards the hadal realm, and that TEX86 from hadal settings robustly records an integrated regional SST signal.Xu, Y., Wu, W., Xiao, W., Ge, H., Wei, Y., Yin, X., Yao, H., Lipp, J.S., Pan, B., Hinrichs, K.-U., 2020. Intact ether lipids in trench sediments related to archaeal community and environmental conditions in the deepest ocean. Journal of Geophysical Research: Biogeosciences 125, e2019JG005431.: Archaea play an important role in marine biogeochemical cycle; however, their phylogenetic distribution and lipid composition in the hadal zone (6–11 km water depth) are poorly known. Here, we analyzed archaeal membrane lipids and 16S rRNA gene sequences in sediments from Mariana Trench (MT), Massau Trench (MS), and New Britain Trench (NBT), varying from 1,560 to 10,840 m depth. Forty‐two intact polar lipids (IPLs) were identified, including glycerol dialkyl glycerol tetraethers (GDGTs), OH‐GDGTs, glycerol dialkyl diethers (GDDs), and archaeol (AR) with polar headgroups of monohexose (1G), dihexose (2G), trihexose (3G), and hexose‐phosphohexose (HPH). Compositional and spatial distribution patterns of archaeal lipids suggest benthic Thaumarchaeota as a major source for IPLs, consistent with the predominance of Thaumarchaeota genes (>80%). The redundancy analysis (RDA) based on lipid and 16S rRNA data separates samples into three groups: extremely deep water (MT), significant terrestrial influence (NBT 1, 4, and 6), and predominant marine influence (MS, NBT 2, 3, 7, and 10). 1G‐GDDs and 1G‐AR positively correlate with water depth, likely reflecting the adaptation of benthic archaea to elevated hydrostatic pressure or variation of archaeal community in trench sediments. Bathyarchaeota are more abundant in sediments receiving terrestrial input; this pattern was attributed to their capability of utilizing terrestrial organic matter as an energy source. Our study highlights important environmental influences (e.g., pressure and organic matter quality and quantity) on benthic archaeal community and archaeal IPL compositions, which should be considered when IPLs and core lipids are applied as chemotaxonomic markers and paleo‐proxies.Plain Language Summary: This work is the first report on intact polar lipids (IPLs) of archaea in the hadal trenches, the deepest ocean realm with water depth exceeding 6,000 m. We have investigated in IPL biomarker 16S rRNA gene sequences and biogeochemical parameters in 19 sediments from the Mariana Trench, Massau Trench, and New Britain Trench. These samples are characterized by different water depth (1,560 to 10,840 m), net primary productivity (48 to 123 C m?2 year?1), and terrestrial influence. By comparing biomarker, gene data, and bulk geochemical parameters, we have achieved three key findings: (1) Benthic Thaumarchaeota are a major source for IPLs in hadal sediments; (2) Some IPLs positively correlate with water depth, likely reflecting an adaption mechanism of benthic archaea to elevated hydrostatic pressure or variation of archaeal community in different environments; and (3) Bathyarchaeota are more abundant in sediments receiving terrestrial input (New Britain Trench); this pattern is attributed to their capability of utilizing terrestrial organic matter as an energy source. Our findings provide important information toward understanding of the distribution and adaptation of hadal microbes to extremely high pressure, dark, and food‐depleted environments.Xu, Z.-X., Li, S.-Y., Li, B.-F., Chen, D.-Q., Liu, Z.-Y., Li, Z.-M., 2020. A review of development methods and EOR technologies?for carbonate reservoirs. Petroleum Science 17, 990-1013. reservoirs worldwide are complex in structure, diverse in form, and highly heterogeneous. Based on these characteristics, the reservoir stimulation technologies and fluid flow characteristics of carbonate reservoirs are briefly described in this study. The development methods and EOR technologies of carbonate reservoirs are systematically summarized, the relevant mechanisms are analyzed, and the application status of oil fields is catalogued. The challenges in the development of carbonate reservoirs are discussed, and future research directions are explored. In the current development processes of carbonate reservoirs, water flooding and gas flooding remain the primary means but are often prone to channeling problems. Chemical flooding is an effective method of tertiary oil recovery, but the harsh formation conditions require high-performance chemical agents. The application of emerging technologies can enhance the oil recovery efficiency and environmental friendliness to a certain extent, which is welcome in hard-to-recover areas such as heavy oil reservoirs, but the economic cost is often high. In future research on EOR technologies, flow field control and flow channel plugging will be the potential directions of traditional development methods, and the application of nanoparticles will revolutionize the chemical EOR methods. On the basis of diversified reservoir stimulation, combined with a variety of modern data processing schemes, multichannel EOR technologies are being developed to realize the systematic, intelligent, and cost-effective development of carbonate reservoirs.Yakimovich, K.M., Orland, C., Emilson, E.J.S., Tanentzap, A.J., Basiliko, N., Mykytczuk, N.C.S., 2020. Lake characteristics influence how methanogens in littoral sediments respond to terrestrial litter inputs. The ISME Journal 14, 2153-2163. lake sediments harbor methanogen communities that are responsible for large amounts of CH4 flux to the atmosphere. These communities play a major role in degrading in-fluxed terrestrial organic matter (t-OM)—much of which settles in shallow near-shore sediments. Little work has examined how sediment methanogens are affected by the quantity and quality of t-OM, and the physicochemical factors that shape their community. Here, we filled mesocosms with artificial lake sediments amended with different ratios and concentrations of coniferous and deciduous tree litter. We installed them in three boreal lakes near Sudbury, Canada that varied in trophic status and water clarity. We found that higher endogenous nutrient concentrations led to greater CH4 production when sediment solar irradiance was similar, but high irradiance of sediments also led to higher CH4 concentrations regardless of nutrient concentrations, possibly due to photooxidation of t-OM. Sediments with t-OM had overall higher CH4 concentrations than controls that had no t-OM, but there were no significant differences in CH4 concentrations with different t-OM compositions or increasing concentrations over 25%. Differences among lakes also explained variation in methanogen community structure, whereas t-OM treatments did not. Therefore, lake characteristics are important modulators of methanogen communities fueled by t-OM.Yakubov, M.R., Abilova, G.R., Yakubova, S.G., Mironov, N.A., 2020. Composition and properties of heavy oil resins. Petroleum Chemistry 60, 637-647. review discusses currently relevant methods for studying petroleum resins. A significant proportion of the research work deals with the study of resins in heavy oils, for which experimental approaches have been systematized and the possibilities and limitations of the mass spectrometric, spectroscopic, X-ray, and chromatographic methods have been discussed. Published data on the effect of resins on the stability of asphaltenes in heavy oils and other petroleum stocks has been analyzed. In addition to experimental approaches, an important factor for understanding the role of resins in the aggregation of asphaltenes is studying their intermolecular interactions using quantum-mechanical calculations. Commonly known approaches to the concentration, fractionation, and purification of heteroatomic petroleum components from heavy oil resins using extraction and chromatographic methods for the isolation of chemical compounds from complex multicomponent mixtures have also been considered.Yan, C., Zheng, M., Desyaterik, Y., Sullivan, A.P., Wu, Y., Collett Jr, J.L., 2020. Molecular characterization of water-soluble brown carbon chromophores in Beijing, China. Journal of Geophysical Research: Atmospheres 125, e2019JD032018. abundance and strong light absorption of atmospheric brown carbon (BrC) have been reported in East Asia, especially in northern China. However, the molecular‐level understanding of BrC chromophores in this area is still limited and quite challenging. In this study, elemental composition of individual BrC chromophores was first investigated in the megacity of Beijing, China, using a powerful platform for the characterization of BrC chromophores, with combination of high‐performance liquid chromatography coupled to a UV/Vis absorbance detector and a time‐of‐flight mass spectrometer with an electrospray ionization source. The results from this study showed that S‐containing compounds (e.g., CHOS and CHONS) significantly increased in highly polluted days compared to lightly polluted days, probably due to increased emissions from sources such as coal combustion and favorable conditions for organosulfates formation. It was found that CHON and CHO compounds were the most abundant water‐soluble organic compounds in Beijing especially during the wintertime. Nitroaromatic compounds were the major water‐soluble BrC chromophores, with three major BrC chromophores (e.g., C6H5NO3, C7H7NO4, and C6H5NO4) found under all conditions, while other specific BrC chromophores with CHON‐ and CHO‐containing elemental formulas identified and varied in different seasons and pollution conditions. Overall, the water‐soluble BrC chromophores identified in this study explained about 2%–18% of the bulk BrC absorbance over the wavelength range of 300–400 nm. In‐depth studies on exploring more BrC chromophores as well as their chemical structures, related sources, and formation mechanisms should be conducted in the future.Yang, H., Wu, G., Scarselli, N., Sun, C., Qing, H., Han, J., Zhang, G., 2020. Characterization of reservoirs, fluids, and productions from the Ordovician carbonate condensate field in the Tarim Basin, northwestern China. American Association of Petroleum Geologists Bulletin 104, 1567-1592. TZ-No1 gas field in the Tarim Basin is the largest condensate field in China; however, it has not developed efficiently because of low and unpredictable production during the past 20 yr. Cores, logging interpretation, seismic descriptions, fluid properties, and production data indicate that this Ordovician carbonate field is different from conventional stratigraphic oil and gas fields as follows: (1) the hydrocarbon-bearing area covers a large region of 2000 km2; (2) matrix reservoirs have low porosity (<6%) and low permeability (<1 md) and small throat radii (<1 μm), but superimposed fracture caves with high porosity and permeability are present, resulting in strong lateral poroperm heterogeneity; (3) significant variations in fluid properties and phases as well as the absence of a uniform oil–water contact; (4) except for some “sweet spots” in large fracture caves, economic production requires acid fracturing and horizontal drilling, yet there are many poorly performing wells with complex output of oil, gas, and water; and (5) more than 70% of the production come from fracture-cave sweet spots but with a high decline of production rates (>20% per year). An examination of the carbonate reservoir and hydrocarbon accumulation history suggests that this large-scale stratigraphic accumulation formed during hydrocarbon emplacement in the early Paleozoic, with the reservoirs gradually evolving into tight reservoirs as a result of intense diagenesis. Variable amounts of Neogene gas charged the tight carbonate reservoirs and formed unconventional accumulations. The TZ-No1 gas field is characterized by a strongly heterogeneous tight matrix reservoir with a superimposed fracture-cave reservoir and a complicated unconventional fluid distribution, which provides insights into the exploitation challenges of unconventional carbonate resources.Yang, M.A., Fan, X., Sun, B., Chen, C., Lang, J., Ko, Y.-C., Tsang, C.-h., Chiu, H., Wang, T., Bao, Q., Wu, X., Hajdinjak, M., Ko, A.M.-S., Ding, M., Cao, P., Yang, R., Liu, F., Nickel, B., Dai, Q., Feng, X., Zhang, L., Sun, C., Ning, C., Zeng, W., Zhao, Y., Zhang, M., Gao, X., Cui, Y., Reich, D., Stoneking, M., Fu, Q., 2020. Ancient DNA indicates human population shifts and admixture in northern and southern China. Science 369, 282-288.: Human genetic history in East Asia is poorly understood. To clarify population relationships, we obtained genome-wide data from 26 ancient individuals from northern and southern East Asia spanning 9500 to 300 years ago. Genetic differentiation in this region was higher in the past than the present, which reflects a major episode of admixture involving northern East Asian ancestry spreading across southern East Asia after the Neolithic, thereby transforming the genetic ancestry of southern China. Mainland southern East Asian and Taiwan Strait island samples from the Neolithic show clear connections with modern and ancient individuals with Austronesian-related ancestry, which supports an origin in southern China for proto-Austronesians. Connections among Neolithic coastal groups from Siberia and Japan to Vietnam indicate that migration and gene flow played an important role in the prehistory of coastal Asia.Editor's summary: A genetic history of China. The history of human movements into and within China has been difficult to determine solely from archaeological investigations or genetic studies of contemporary peoples. Yang et al. sequenced DNA from 26 individuals from 9500 to 300 years ago from locations within China. Analyses of these individuals, along with previously sequenced ancient individuals and present-day genomes representing global populations, show a split between ancient humans in northern and southern China. Neolithic northern Chinese individuals are closest to modern-day East Asians, whereas ancient individuals from southern China are most closely related to modern-day Southeast Asians and show an affinity to modern-day Austronesian populations. These results indicate that there was a southward movement and admixture of peoples during the Neolithic that gave rise to modern-day populations in East Asia.Yang, S., Hu, W., Yao, S., Wang, X., He, W., Wang, Y., Zhu, F., Sun, F., 2020. Constraints on the accumulation of organic matter in Upper Ordovician-lower Silurian black shales from the Lower Yangtze region, South China. Marine and Petroleum Geology 120, 104544. Late Ordovician to early Silurian (O/S) was an important period in which many significant geological events occurred. During the O/S transition, organic-rich black shales were widely deposited and became important unconventional energy sources. Paleoproductivity, detrital input, and redox conditions are the three major factors controlling organic matter (OM) accumulation. Although the effect of each factor is relatively clear, the complex influences of these factors remain poorly understood. Specifically, the evolution of these factors and the corresponding influence on the accumulation of OM during the O/S transition has not yet been systematically investigated. This paper investigates the constraints on OM accumulation in O/S transition black shales from the Lower Yangtze region, based on graptolite fossil identification, zircon U–Pb dating, and geochemical analyses of a well sequenced drilling profile. The results show that (i) the SY-1 core sequence was well constrained from graptolite zones WF2 (447.62?Ma) to LM5 (441.57?Ma) across the O/S boundary, with decreasing sedimentation rates (SRs) in the upper Katian (WF2 to WF3) and increasing SRs in the lower Rhuddanian; (ii) complementary volcanic inputs (Katian and Rhuddanian) and upwelling events (Hirnantian) exerted strong control over paleoproductivity; (iii) orogenic processes in South China controlled detrital inputs and redox conditions; (iv) OM accumulation in the Lower Yangtze area across the O/S transition occurred in three stages. In stage 1 (WF2–WF3), strong volcanism boosted productivity, whereas OM preservation was not favored in the oxic environment. In stage 2 (WF4–LM3), upwelling and volcanism resulted in high productivity and provided the optimal configurations for OM enrichment. In stage 3 (LM4 and later), rare OM was preserved due to terrestrial dilution and unfavorable preservation conditions. Eventually, WF4–LM3 became the prominent OM-rich biozones due to the effective coordination of the controlling factors, namely upwelling, volcanism, and redox conditions.Yang, Y., Liu, W., Zhang, Z., Grossart, H.-P., Gadd, G.M., 2020. Microplastics provide new microbial niches in aquatic environments. Applied Microbiology and Biotechnology 104, 6501-6511. in the biosphere are currently of great environmental concern because of their potential toxicity for aquatic biota and human health and association with pathogenic microbiota. Microplastics can occur in high abundance in all aquatic environments, including oceans, rivers and lakes. Recent findings have highlighted the role of microplastics as important vectors for microorganisms, which can form fully developed biofilms on this artificial substrate. Microplastics therefore provide new microbial niches in the aquatic environment, and the developing biofilms may significantly differ in microbial composition compared to natural free-living or particle-associated microbial populations in the surrounding water. In this article, we discuss the composition and ecological function of the microbial communities found in microplastic biofilms. The potential factors that influence the richness and diversity of such microbial microplastic communities are also evaluated. Microbe-microbe and microbe-substrate interactions in microplastic biofilms have been little studied and are not well understood. Multiomics tools together with morphological, physiological and biochemical analyses should be combined to provide a more comprehensive overview on the ecological role of microplastic biofilms. These new microbial niches have so far unknown consequences for microbial ecology and environmental processes in aquatic ecosystems. More knowledge is required on the microbial community composition of microplastic biofilms and their ecological functions in order to better evaluate consequences for the environment and animal health, including humans, especially since the worldwide abundance of microplastics is predicted to dramatically increase.Key Points? Bacteria are mainly studied in community analyses: fungi are neglected.? Microbial colonization of microplastics depends on substrate, location and time.? Community ecology is a promising approach to investigate microbial colonization.? Biodegradable plastics, and ecological roles of microplastic biofilms, need analysis.Yang, Z., Chen, Y.-F., Niemi, A., 2020. Gas migration and residual trapping in bimodal heterogeneous media during geological storage of CO2. Advances in Water Resources 142, 103608. study investigates the effect of heterogeneity on CO2–brine two-phase flow behavior and capillary trapping at the field scale. A model based on macroscopic invasion percolation is developed to simulate CO2 migration and trapping in strongly heterogeneous systems with bimodal permeability distributions. Stochastic simulations are performed on heterogeneous permeability fields generated by considering both transition probability based lithofacies distribution and multi-Gaussian random fields, representative of characteristics often encountered in relevant sedimentary basins. The heterogeneity cases of different lithofacies proportions are designed such that they share the same ensemble mean of upscaled permeability over the simulation domain. We find that the CO2 spreading and trapping is strongly influenced by the heterogeneity. The ensemble means of sweep efficiency and domain-average CO2 saturation after primary drainage show a slight decrease with decreasing sandstone proportion p1 from 1.0 to 0.6 but a much steeper decline when p1 further decreases to 0.4. The upscaled two-phase flow properties such as the relative permeabilities are also influenced by the lithofacies proportion. Residual or capillary trapping and its uncertainty is shown to be dependent on the heterogeneity and the choice of trapping models. Our findings have broad implications within the context of CO2 sequestration, as the gas spreading and entrapment are the fundamental processes leading to long-term storage security.Yao, Y., Zhao, J., Vachula, R.S., Werne, J.P., Wu, J., Song, X., Huang, Y., 2020. Correlation between the ratio of 5-methyl hexamethylated to pentamethylated branched GDGTs (HP5) and water depth reflects redox variations in stratified lakes. Organic Geochemistry 147, 104076. glycerol dialkyl glycerol tetraethers (brGDGTs) are potentially valuable biomarkers for paleoclimatic and paleoenvironmental studies. However, multiple factors controlling their variations in lake sediments hamper the widespread application of brGDGT-based proxies. Here we investigate brGDGTs in water column suspended particulate matter (SPM) and surface sediments in a series of lakes with a wide range of depths from three main volcanic fields of northeastern China. The brGDGT distribution patterns from SPM and surface sediments of these lakes differ greatly from those of surrounding soils, indicating a predominant aquatic origin for brGDGTs. We find that the ratio of 5-methyl hexamethylated and pentamethylated brGDGTs with no cyclopentane rings (IIIa/(IIa?+?IIIa); designated as HP5) is strongly correlated with water depth. Re-examination of published brGDGT data from SPM samples in redox-stratified Lake Lugano reveals similar relationships, whereas such correlations are much weaker in Lake Superior which does not have an anoxic hypolimnion. Importantly, we find that there is strong correlation between HP5 and dissolved oxygen in water column of the redox-stratified lakes, suggesting that the observed apparent HP5–water depth correlation may be primarily attributed to depth-progressive shifts in the brGDGT-producing bacterial communities with different redox requirements (aerobic, facultative anaerobic, and anaerobic bacteria). Notably, brGDGT methylation indices (MBT?5ME and MBT?6ME) of surface sediments display poor correlations with air temperatures in our study lakes, calling for caution in applying MBT?5ME and MBT?6ME as temperature proxies in these lakes.Yatsuk, A., Shakirov, R., Gresov, A., Obzhirov, A., 2020. Hydrocarbon gases in seafloor sediments of the TATAR strait, the northern sea of Japan. Geo-Marine Letters 40, 481-490. distributions of hydrocarbon gases (HCGs) from C1-C5 in seafloor sediments of the South Tatar sedimentary basin (northern Sea of Japan) were obtained during five research cruises from 2012 to 2017. As a result of this work, areas of gas hydrates, gas flares, and anomalous gas concentrations were discovered. The concentration of HCGs in seafloor sediment, as determined by the “headspace method” varied from 0.38 to 149,000 ppm, with a median of 177 ppm (N =?1420). The median values of HCGs for the Western, Central, and Eastern part of the South Tatar sedimentary basin are 11.7, 99, and 1134 ppm, respectively. Maximum values and gradients in concentrations of HCGs were found in the central and eastern parts of Tatar Strait, where multiple cores contain gas hydrates and gas-saturated sediments. The predominant gas component in all samples was methane, but relatively high concentrations of ethane (up to 789 ppm) and propane (up to 111 ppm) occur. Methane concentrations below 5.25 ppm can be considered as regional background for near seafloor (0–15 cm) sediments from the South Tatar sedimentary basin. The С1/(С2?+?С3) ratio across all samples ranges between 2.6 and 345,000, with a median value of 219. The presence of a large-scale degassing zone exists in the northeastern part of Tatar Strait, which coincides with areas of gas hydrates and gas anomalies in the sediments and gas flares in the water column.Ye, J.-l., Qin, X.-w., Xie, W.-w., Lu, H.-l., Ma, B.-j., Qiu, H.-j., Liang, J.-q., Lu, J.-a., Kuang, Z.-g., Lu, C., Liang, Q.-y., Wei, S.-p., Yu, Y.-j., Liu, C.-s., Li, B., Shen, K.-x., Shi, H.-x., Lu, Q.-p., Li, J., Kou, B.-b., Song, G., Li, B., Zhang, H.-e., Lu, H.-f., Ma, C., Dong, Y.-f., Bian, H., 2020. The second natural gas hydrate production test in the South China Sea. China Geology 3, 197-209. silt reservoirs bearing natural gas hydrates (NGH) are considered to be the hydrate-bearing reservoirs that boast the highest reserves but tend to be the most difficult to exploit. They are proved to be exploitable by the first NGH production test conducted in the South China Sea in 2017. Based on the understanding of the first production test, the China Geological Survey determined the optimal target NGH reservoirs for production test and conducted a detailed assessment, numerical and experimental simulation, and onshore testing of the reservoirs. After that, it conducted the second offshore NGH production test in 1225 m deep Shenhu Area, South China Sea (also referred to as the second production test) from October 2019 to April 2020. During the second production test, a series of technical challenges of drilling horizontal wells in shallow soft strata in deep sea were met, including wellhead stability, directional drilling of a horizontal well, reservoir stimulation and sand control, and accurate depressurization. As a result, 30 days of continuous gas production was achieved, with a cumulative gas production of 86.14 ×104 m3. Thus, the average daily gas production is 2.87 ×104 m3, which is 5.57 times as much as that obtained in the first production test. Therefore, both the cumulative gas production and the daily gas production were highly improved compared to the first production test. As indicated by the monitoring results of the second production test, there was no anomaly in methane content in the seafloor, seawater, and atmosphere throughout the whole production test. This successful production test further indicates that safe and effective NGH exploitation is feasible in clayey silt NGH reservoirs. The industrialization of hydrates consists of five stages in general, namely theoretical research and simulation experiments, exploratory production test, experimental production test, productive production test, and commercial production. The second production test serves as an important step from the exploratory production test to experimental production test.Yi, C., Zhang, M., Teng, L., 2020. Maturity effects on steranes of source rocks in Lishu fault depression, Songliao Basin. Acta Geochimica 39, 561-573. analysis results of 30 source rock samples from Lishu fault depression in Songliao Basin show that samples are compositionally similar and represent a uniform organic facies. Differential distribution of steranes among the samples is due to rank, with vitrinite reflectances (Ro) ranging from 0.65 to 1.61%. In the maturity stage (Ro?=?0.65–1.20%), the absolute concentrations of steranes increase, which is affected by kerogen degradation, whereas the pyrolysis of high mature source (Ro?=?1.20–1.61%) show a decrease in the abundance of steranes. Simultaneously, the parameters of steranes vary greatly with maturity. Decrease of prognane/regular sterane value with the increase of maturity suggests that pregnane is not a product of regular steranes pyrolysis. The ratios of C27/C29 regular sterane gradually increase, while the value of C29-20S/(20S?+?20R) and αββ/(αββ?+?ααα) decrease at high maturity stage, which is associated with the difference in the thermostability of steranes involved. This reversed trend can be used to determine the high-maturity stage of source rocks. Whereas the values of rearranged steranes/regular steranes in source rocks show an apparent positive correlation with maturity, it, therefore, appears to be particularly useful for maturity assessment at elevated levels.Yin, S., Wang, Z., Lu, C., Li, H., 2020. Towards accurate phase behavior modeling for hydrogen sulfide/water mixtures. Fluid Phase Equilibria 521, 112691. deep gas wells contain acid gas components. Hydrogen sulfide (H2S) is one of the typical acid gases. Accurate flow simulations for H2S/H2O mixtures in reservoirs and wellbores requires a proper thermodynamic model that is capable of accurately modeling the H2S/H2O mixtures under in-situ conditions. This study aims at screening and developing cubic-equation-of-state-based thermodynamic models that can well describe the phase behavior of H2S/H2O mixtures. Peng-Robinson equation of state (PR EOS) (Peng and Robinson, 1976) and the Huron-Vidal (HV) (Huron and Vidal, 1979) mixing rule are used as the primary modeling framework. The temperature-dependent binary interaction parameter (BIP) correlations in the HV mixing rule are established by matching the measured vapor-liquid equilibria (VLE) data for H2S/H2O mixtures collected from the literature. The experimental VLE data cover a temperature range of 273.15–627.85 K and a pressure range of 0.41–303 bar, while the experimental density data cover a temperature range of 294.35–705.30 K and pressures up to 350 bar. Different volume translation strategies are examined in terms of their accuracy in reproducing the measured density data for H2S/H2O mixtures. We employ PR EOS together with the optimal BIP strategy in the HV mixing rule to reproduce the mutual solubility of H2S and H2O in VLE. The calculated results show a good agreement with the experimental data, especially at high temperatures and pressures; the average absolute percentage deviation (%AAD) of 4.90% and 4.95% can be obtained for reproducing the vapor-phase H2O solubility and the aqueous-phase H2S solubility, respectively. With the inclusion of the volume translation model proposed by Abudour et al. (2013), PR EOS together with the optimal BIP strategy in the HV mixing rule shows a good performance in estimating the aqueous-phase density for H2S/H2O VLE, i.e., an %AAD of 5.42% in reproducing the measured density data.Yu, H., Leadbetter, J.R., 2020. Bacterial chemolithoautotrophy via manganese oxidation. Nature 583, 453-458. is one of the most abundant elements on Earth. The oxidation of manganese has long been theorized—yet has not been demonstrated—to fuel the growth of chemolithoautotrophic microorganisms. Here we refine an enrichment culture that exhibits exponential growth dependent on Mn(II) oxidation to a co-culture of two microbial species. Oxidation required viable bacteria at permissive temperatures, which resulted in the generation of small nodules of manganese oxide with which the cells associated. The majority member of the culture—which we designate ‘Candidatus Manganitrophus noduliformans’—is affiliated to the phylum Nitrospirae (also known as Nitrospirota), but is distantly related to known species of Nitrospira and Leptospirillum. We isolated the minority member, a betaproteobacterium that does not oxidize Mn(II) alone, and designate it Ramlibacter lithotrophicus. Stable-isotope probing revealed 13CO2 fixation into cellular biomass that was dependent upon Mn(II) oxidation. Transcriptomic analysis revealed candidate pathways for coupling extracellular manganese oxidation to aerobic energy conservation and autotrophic CO2 fixation. These findings expand the known diversity of inorganic metabolisms that support life, and complete a biogeochemical energy cycle for manganese that may interface with other major global elemental cycles.Yu, H., Yang, B., Waigi, M.G., Peng, F., Li, Z., Hu, X., 2020. The effects of functional groups on the sorption of naphthalene on microplastics. Chemosphere 261, 127592. microplastics were recognized as an ideal carrier for polycyclic aromatic hydrocarbons (PAHs) to spread in nature or transfer to biota, thus posing risks to human health. However, little is known about how the functional groups in PAH derivatives influence their sorption onto microplastics as compared to parent PAHs. This study investigated the sorption of naphthalene (NAP) and its derivatives onto polystyrene microspheres with (MP-COOH) or without (MP) surface modification of the carboxyl group. NAP derivatives with charged groups (e.g., –NH2, –OH and –COOH) reached the sorption equilibrium more early than NAP and its derivative with an uncharged group (e.g., –CH3), whereas their sorption capacities (Kd = 6.0–8.4 L/g for MP, Kd = 4.5–6.3 L/g for MP-COOH) were significantly lower than that of the latter (Kd = 11.6–12.0 L/g for MP, Kd = 9.4–10.0 L/g for MP-COOH). The inhibition of charged groups on sorption could be attributed to their facilitation on molecular polarity and, thus, their lower hydrophobicity (LogKOW) since hydrophobicity was the crucial factor controlling the sorption of NAP and NAP derivatives onto both MP and MP-COOH. Computational modeling further showed that charged functional groups would weaken the π-π interaction or strengthen the repulsion between NAP or NAP derivative molecule and MP or MP-COOH molecule, which might also contribute to the suppressed sorption. This study provides new insight into the affinity of PAH derivatives with microplastics, which, therefore, improves our understanding of the environmental fates of microplastics and the organic pollutants.Yu, X., Li, J., Chen, Z., Wu, K., Zhang, L., Hui, G., Yang, M., 2020. Molecular dynamics computations of brine-CO2/CH4-shale contact angles: Implications for CO2 sequestration and enhanced gas recovery. Fuel 280, 118590. rock wettabilities and water contact angles describing interactions between CO2, CH4, brine and shale formations are of great significance to CO2 sequestration and enhanced gas recovery processes. However, water contact angles on the surfaces of shale organic matter in the atmospheres of CO2 and CH4 under reservoir conditions are not well-understood. In this study, we present an investigation of water/brine contact angles as functions of temperature, pressure, salinity, ion types, and gas contents by molecular dynamics simulations, and compare results with data from literature. It is found that temperature has profound effects on water contact angles below the critical temperature at an intermediate pressure. Meanwhile, water contact angles increase with pressure before reaching 180° at high pressure and the CO2-water-shale organic matter system turns from a neutrally-wet state to a CO2-wet state at the critical pressure of CO2. We also demonstrate that salinity and ion types have minor impacts on the brine contact angles in the CO2-brine-shale system. Only a slight increase in water contact angles is observed with increasing salinity, and an increase in brine contact angles caused by the divalent cations Mg2+ and Ca2+ is larger than that by the monovalent cations Na+ at the same salinity. Additionally, an increase in the CO2 fraction of gas mixtures can increase water contact angles at the same pressure and temperature. The surfaces of shale organic matter have a stronger affinity for CO2 than CH4, which contributes to a higher CO2 adsorption capacity and improves the displacement efficiency of CH4.Yu, X., Zholobenko, V.L., Moldovan, S., Hu, D., Wu, D., Ordomsky, V.V., Khodakov, A.Y., 2020. Stoichiometric methane conversion to ethane using photochemical looping at ambient temperature. Nature Energy 5, 511-519. activation and utilization are among the major challenges of modern science. Methane is potentially an important feedstock for manufacturing value-added fuels and chemicals. However, most known processes require excessive operating temperatures and exhibit insufficient selectivity. Here, we demonstrate a photochemical looping strategy for highly selective stoichiometric conversion of methane to ethane at ambient temperature over silver–heteropolyacid–titania nanocomposites. The process involves a stoichiometric reaction of methane with highly dispersed cationic silver under illumination, which results in the formation of methyl radicals. Recombination of the generated methyl radicals leads to the selective, and almost quantitative, formation of ethane. Cationic silver species are simultaneously reduced to metallic silver. The silver–heteropolyacid–titania nanocomposites can be reversibly regenerated in air under illumination at ambient temperature. The photochemical looping process achieves a methane coupling selectivity of over 90%, a quantitative yield of ethane of over 9%, high quantum efficiency (3.5% at 362?nm) and excellent stability.Yudina, N.V., Loskutova, Y.V., 2020. Formation of organic deposits in model petroleum systems. Petroleum Chemistry 60, 693-698. formation of organic deposits in model petroleum-containing systems of various compositions has been studied. Introduction of asphaltene–resin substances into a model paraffin system reduces the amount of precipitated wax deposit to 40 wt %; significantly changes the ratio of liquid and solid hydrocarbons in the n-alkane composition of the deposits, shifting the distribution maximum towards a lower molecular weight; and substantially reduces the mechanical strength. In the model paraffin system in the presence of resins and asphaltenes, which contain a greater amount of condensed aromatic structures and a smaller amount of paraffin structures, a precipitate is formed with an increased proportion of the liquid phase. The deposits are characterized by lower strength of the crystal lattice and, hence, a decreased value of ultimate shear stress.Zabanbark, A., Lobkovsky, L.I., 2020. Role of Brazil’s continental slopes in being provided with hydrocarbon resources. Oceanology 60, 259-266. more of 80 hydrocarbon fields, mainly oil-producing, in the deepwater part of the Santos, Campos and Espirito Santo basins reveal the tendency of these large fields to lie in a productive oil-pay belt extending in the sea depth from range from 400 to 2500 m (possibly 3000 m or more) in a system of external depressions stretching along the lower part of the continental slope. This belt may continued to the north. All the fields in this belt in reserves category are estimated as large and giant. In the last 10–15 years, exploration works have been conducted in this belt already in the presalt formation: in the Santos Basin, 29 fields; in the Campos Basin, 21; and in the Espirito Santo Basin 7. It is noteworthy that 48% of the total hydrocarbon production of the country formed in presalt carbonate deposits of the Aptian Formation on the continental slope, 44% postsalt rocks on the continental slope and shelf, and only 8% is attributed to the mainland. In the world, Brazil’s deepwater presalt Aptian Formation (Barremian–Aptian in the Santos Basin) is essentially unique. In recent decades, giant hydrocarbon accumulations have been discovered, thereby doubling the country’s oil and gas reserves to total reserves of more than 3 billion t and 4.7 trillion m3, respectively. The geology of the presalt formation is narrowly related to tectonic movements that took place during the breakup of the Gondwana supercontinent into the South American and African continents. This took place 150 Ma ago in the Early Cretaceous. The salt of the Aptian Formation is an excellent caprock, the presalt reservoirs are superior in their characteristics, the oil is light and sweet, and the source rocks are enriched in organic matter. The thickness of the Aptian salt is limited, varying from basin to basin; the main width of the salt is in the Santos Basin 400 km and the thickness is 2000 m; in the north, the thickness and width decrease; in the Sergipi Alagoas Basin, it already reaches 100 m.Zahn, D., Neuwald, I.J., Knepper, T.P., 2020. Analysis of mobile chemicals in the aquatic environment—current capabilities, limitations and future perspectives. Analytical and Bioanalytical Chemistry 412, 4763-4784. and mobile water contaminants are rapidly developing into a focal point of environmental chemistry and chemical regulation. Their defining parameter that sets them apart from the majority of regularly monitored and regulated contaminants is their mobility in the aquatic environment, which is intrinsically tied to a high polarity. This high polarity, however, may have severe implications in the analytical process and thus the most polar of these mobile contaminants may not be covered by widely utilized trace-analytical methods, and thus, alternatives are required. In this review, we infer the physical and chemical properties of mobile water contaminants from a set of almost 1800 prioritized REACH chemicals and discuss the implications these substance properties may have on four integral steps of the analytical process: sampling and sample storage, sample pre-treatment, separation and detection. We discuss alternatives to widely utilized trace-analytical methods, examine their application range and limitations, highlight potential analytical techniques on the horizon and emphasize research areas we believe still offer the most room for further improvement. While we have a comprehensive set of analytical methods to cover a large portion of the known mobile chemicals, these methods are still only infrequently utilized.Z?ncker, B., Cunliffe, M., Engel, A., 2020. Eukaryotic community composition in the sea surface microlayer across an east-west transect in the Mediterranean Sea. Biogeosciences Discussions 2020, 1-20. sea surface microlayer (SML) represents the boundary layer at the air-sea interface. Microbial eukaryotes in the SML potentially influence air-sea gas exchange directly by taking up and producing gases, and indirectly by excreting and degrading organic matter, which may modify the viscoelastic properties of the SML. However, little is known about the controlling factors that influence microbial eukaryote community composition in the SML. We studied the composition of the microbial community, transparent exopolymer particles and polysaccharides in the SML during the PEACETIME cruise along a west-east transect in the Mediterranean Sea, covering the western basin, Tyrrhenian Sea and Ionian Sea. At the stations located in the Ionian Sea, fungi were found in high relative abundances determined by 18S sequencing efforts, making up a significant proportion of the sequences recovered. At the same time, bacterial and phytoplankton counts were decreasing from west to east, while transparent exopolymer particle (TEP) abundance and total carbohydrate (TCHO) concentrations remained the same between Mediterranean basins. Thus, the presence of substrates for fungi, such as Cladosporium known to take up phytoplankton-derived polysaccharides, in combination with decreased substrate competition by bacteria suggests that fungi could be thriving in the neuston of the Ionian Sea.Zanella, D., Henket, M., Schleich, F., Dejong, T., Louis, R., Focant, J.-F., Stefanuto, P.-H., 2020. Comparison of the effect of chemically and biologically induced inflammation on the volatile metabolite production of lung epithelial cells by GC×GC-TOFMS. Analyst 145, 5148-5157. breath analysis has a high potential for early non-invasive diagnosis of lung inflammatory diseases, such as asthma. The characterization and understanding of the inflammatory metabolic pathways involved into volatile organic compounds (VOCs) production could bring exhaled breath analysis into clinical practice and thus open new therapeutic routes for inflammatory diseases. In this study, lung inflammation was simulated in vitro using A549 epithelial cells. We compared the VOC production from A549 epithelial cells after a chemically induced oxidative stress in vitro, exposing the cells to H2O2, and a biological stress, exposing the cells to an inflammatory pool of sputum supernatants. Special attention was devoted to define proper negative and positive controls (8 different types) for our in vitro models, including healthy sputum co-culture. Sputum from 25 asthmatic and 8 healthy patients were collected to create each pool of supernatants. Each sample type was analyzed in 4 replicates using solid-phase microextraction (SPME) comprehensive two-dimensional gas chromatography hyphenated to time-of-flight mass spectrometry (GC×GC-TOFMS). This approach offers high resolving power for complex VOC mixtures. According to the type of inflammation induced, significantly different VOCs were produced by the epithelial cells compared to all controls. For both chemical and biological challenges, an increase of carbonyl compounds (54%) and hydrocarbons (31%) was observed. Interestingly, only the biological inflammation model showed a significant cell proliferation together with an increased VOC production linked to asthma airway inflammation. This study presents a complete GC×GC-TOFMS workflow for in vitro VOC analysis, and its potential to characterize complex lung inflammatory mechanisms.Zhang, C., Chen, Y., Xu, B., Xue, Y., Ren, Y., 2020. Improving prediction of rare species’ distribution from community data. Scientific Reports 10, 12230. distribution models (SDMs) have been increasingly used to predict the geographic distribution of a wide range of organisms; however, relatively fewer research efforts have concentrated on rare species despite their critical roles in biological conservation. The present study tested whether community data may improve modelling rare species by sharing information among common and rare ones. We chose six SDMs that treat community data in different ways, including two traditional single-species models (random forest and artificial neural network) and four joint species distribution models that incorporate species associations implicitly (multivariate random forest and multi-response artificial neural network) or explicitly (hierarchical modelling of species communities and generalized joint attribute model). In addition, we evaluated two approaches of data arrangement, species filtering and conditional prediction, to enhance the selected models. The model predictions were tested using cross validation based on empirical data collected from marine fisheries surveys, and the effects of community data were evaluated by comparing models for six selected rare species. The results demonstrated that the community data improved the predictions of rare species’ distributions to certain extent but might also be unhelpful in some cases. The rare species could be appropriately predicted in terms of occurrence, whereas their abundance tended to be underestimated by most models. Species filtering and conditional predictions substantially benefited the predictive performances of multiple- and single-species models, respectively. We conclude that both the modelling algorithms and community data need to be carefully selected in order to deliver improvement in modelling rare species. The study highlights the opportunity and challenges to improve prediction of rare species’ distribution by making the most of community data.Zhang, C., Zhang, Y., Liu, M., Guan, Y.-M., Yuan, S.-H., 2020. Transformation of sulfur compounds in two typical atmospheric residues in hydrotreating via ESI FT-ICR MS. Fuel 281, 118731. atmospheric residue (AR) hydrotreating (HDT) process attracts more and more attention because it provides quality feedstock for downstream catalytic cracking. The compositional analysis of feeds and products is a key step to improve our understanding of HDT process. In this study, two ARs representing a low (LSAR) and a high sulfur content (HSAR) were hydrotreated in a fixed-bed flow reactor. With increased process severity, we employed electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) to monitor the evolution of the sulfur families in HDT. The results suggest that although the properties and molecular composition of sulfur classes in ARs vary, the evolution of the sulfur compounds is quite similar. Further analysis indicated that the removal difficulty of S1 and S2 species was positively correlated with the number of aromatic rings.Zhang, H., Li, G., Guo, H., Zhang, W., Wang, Y., Li, W., Zhou, J., Wang, C., 2020. Applications of nuclear magnetic resonance (NMR) logging in tight sandstone reservoir pore structure characterization. Arabian Journal of Geosciences 13, 572. sandstone reservoir evaluation and characterization faced great challenge by using conventional well logging data due to the complicated pore structure. To improve tight sandstone reservoir identification, the pore structure should be first characterized. In this study, using the tight Chang 8 Formation of Pengyang Region, west Ordos Basin as an example, 20 core samples were drilled for laboratory nuclear magnetic resonance (NMR) and mercury injection capillary pressure (MICP) experiments. A model, which was used to construct capillary pressure (Pc) curves from NMR data, was proposed, and the corresponding models were established based on classified power function (CPF) method to classify formations into three types. Based on these relationships, the NMR T2 distributions were transformed as pseudo Pc curves and pore throat radius distributions. After these relationships were extended into field applications, consecutive pseudo Pc curves were acquired, and the pore structure evaluation parameters and permeability were also predicted. Comparisons of predicted parameters with core-derived results illustrated the reliability of our proposed model and method.Zhang, H., Xu, J., Zhang, K., Wei, Z., Zhao, Q., Faboya, O.L., Cheng, B., 2020. Geochemical characteristics of carbon and hydrogen isotopes of light crude oils from the deep reservoirs in the Tazhong area of Tarim Basin, NW China. Petroleum Science and Technology 38, 509-515. stable carbon and hydrogen isotopes of light crude oils from deep reservoirs of Cambrian-Ordovician strata in Tazhong area of Tarim Basin, NW China were investigated. The δ13C and δD values determined from the oil samples ranged from ?32.94 to ?29.53‰ and ?121.36 to ?87.78‰, respectively. A positive correlation exists between δ13Coil and δDoil when the δ13Coil < ?31.15‰, while a negative correlation occurs at δ13Coil > ?31.15‰. This basic geochemical data is quite instructive in that the δ13Coil value of approximately ?31‰ may be an important threshold value to delimit the origin of the organic matter that formed the light crude oils.Zhang, J., Brown, J., Scurr, D.J., Bullen, A., MacLellan-Gibson, K., Williams, P., Alexander, M.R., Hardie, K.R., Gilmore, I.S., Rakowska, P.D., 2020. Cryo-OrbiSIMS for 3D molecular imaging of a bacterial biofilm in its native state. Analytical Chemistry 92, 9008-9015. ion mass spectrometry (SIMS) is gaining popularity for molecular imaging in the life sciences because it is label-free and allows imaging in two and three dimensions. The recent introduction of the OrbiSIMS has significantly improved the utility for biological imaging through combining subcellular spatial resolution with high-performance Orbitrap mass spectrometry. SIMS instruments operate in high-vacuum, and samples are typically analyzed in a freeze-dried state. Consequently, the molecular and structural information may not be well-preserved. We report a method for molecular imaging of biological materials, preserved in a native state, by using an OrbiSIMS instrument equipped with cryogenic sample handling and a high-pressure freezing protocol compatible with mass spectrometry. The performance is demonstrated by imaging a challenging sample (>90% water) of a mature Pseudomonas aeruginosa biofilm in its native state. The 3D distribution of quorum sensing signaling molecules, nucleobases, and bacterial membrane molecules is revealed with high spatial-resolution and high mass-resolution. We discover that analysis in the frozen-hydrated state yields a 10?000-fold increase in signal intensity for polar molecules such as amino acids, which has important implications for SIMS imaging of metabolites and pharmaceuticals.Zhang, J., Cao, J., Xia, L., Xiang, B., Li, E., 2020. Investigating biological nitrogen cycling in lacustrine systems by FT-ICR-MS analysis of nitrogen-containing compounds in petroleum. Palaeogeography, Palaeoclimatology, Palaeoecology 556, 109887. nitrogen cycling plays an important role in bio, environmental and petroleum geochemistry. Until now most research has focused on marine environments using nitrogen isotopes, and in contrast, nitrogen cycling in lacustrine environments remains poorly understood. To fill this knowledge gap, we present a case study of crude oils from Permian brackish and saline alkaline lacustrine rocks in the Junggar Basin, northwestern China. To complement the large variation in nitrogen isotope values in lacustrine sediments, we analyzed the pyrrolic N-containing compounds of crude oil using negative ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR-MS). Our results show that pyrrolic compounds derived from biological sources are more abundant in oils from brackish lacustrine settings (i.e., the Jimusar Sag oils of the Junggar Basin) than in oils from alkaline lacustrine settings (i.e., the Mahu Sag oils of the Junggar Basin), which is mainly due to greater higher plant contributions to the latter. Higher plants provide abundant alkaloids and chlorophyll that are the biological precursors of pyrrolic N-containing compounds. In addition, anoxic, sulfate-type, brackish lacustrine settings provide abundant ferrous iron and sulfide that promote N fixation. This study provides the first insights into biological N cycling in brackish and alkaline lacustrine systems, which has significance for fossil fuel resources and their environmental impacts. Our data suggest that the N cycling in lacustrine systems might have an important role in entire Earth system N budget.Zhang, J., Pas, D., Krijgsman, W., Wei, W., Du, X., Zhang, C., Liu, J., Lu, Y., 2020. Astronomical forcing of the Paleogene coal-bearing hydrocarbon source rocks of the East China Sea Shelf Basin. Sedimentary Geology 406, 105715. Paleogene coal-bearing deposits (Pinghu Formation) of the Xihu Depression form the most productive hydrocarbon source in the East China Sea Shelf Basin. Due to the lack of reliable magnetostratigraphic, paleontologic and geochemical/isotope data, these source rocks are still poorly dated. The absence of a robust time frame results in many disputes on the age and duration of the Pinghu Formation and hampers a thorough understanding of its sedimentary evolution. Here, we study the cyclic changes in the depositional environment that can be retrieved from seismic interpretation and sequence stratigraphic analyses of well log data (e.g., stacking patterns, logging, and lithofacies changes). We recognize one second-order sequence, three third-order sequences and 12 fourth-order parasequences. Next, we construct a floating astronomical time scale by using power spectra and evolutionary fast Fourier transformation analysis on the gamma-ray data. Wavelength variations in the gamma-ray spectra show similar ratios as the astronomically-forced Milankovitch cycles (i.e., eccentricity, obliquity and precession). The filtered long and short orbital eccentricity cycles show a good match with the La2010d astronomical target curve, allowing to create an independent time frame based on cyclostratigraphy. Our floating astronomical time scale provides new numerical age constraints for the Pinghu Formation, resulting in a total duration of ~4.95 Myr. A re-analysis of the available age data indicates that the sequence stratigraphic framework of the Pinghu Formation is best constrained to the early Oligocene, instead of the previously assumed late Eocene. Our study highlights that astronomical interpretation of sequence stratigraphic analyses is an excellent method to estimate the duration of sedimentary successions in boreholes and adds to a better understanding of the temporal and spatial sediment distribution patterns in the East China Sea Shelf Basin.Zhang, L., Yan, D., Yang, S., Mangi, H.N., Fu, H., Wang, G., Yang, X., Zhang, B., Li, T., Liang, W., She, X., 2020h. Effects of sequence stratigraphy on coal characteristics and CH4 adsorption capacity of the low-rank coal in Santanghu Basin, China. Journal of Natural Gas Science and Engineering 81, 103467. paper focusses on sequence stratigraphy of coal-bearing strata, coal petrography, coal chemistry, and the CH4 adsorption capacity of the Badaowan Formation in Santanghu Basin, China. The comprehensive coal characteristics of 12 coal samples were determined, coupled with maceral composition, proximate analysis, elemental analysis, reflectance (Ro), and high-pressure CH4 adsorption. The results indicated that maceral composition and chemical properties of coal were controlled by the sequence stratigraphic framework. During the TST, the content of vitrinite, the ratio of vitrinite to inertinite (V/I) and the content of carbon in coal increased gradually from bottom to top. While during HST, an opposite trend was observed. Furthermore, due to the intrusion of the lake water, the ash yield in the TST is higher than that in HST. The CH4 adsorption capacity is positively correlated with the content of vitrinite and V/I. There is a moderate positive correlation between fixed carbon contents and VLad. Ash content was strongly correlated to Langmuir volume under the air-dry basis, with increasing Ad associated with the reduction of the VLad. It was observed that the CH4 adsorption capacity generally gradually increased during the TST, and gradually decreased in the HST. Gas content also shows a similar change rule. CH4 adsorption capacity is functionally dependent on coal characteristics, which again are dependent on sequence stratigraphy and thus the coal-forming environment. The base level and cycles of the sequence establish a theoretical and practical framework for CBM extraction from low-rank coal reservoirs.Zhang, M., Cheng, Q., Zhang, W., 2020. Response of 17α(H)-diahopanes and 18α(H)-neohopanes to maturity in lacustrine source rocks derived from the Songliao Basin, NE China. Arabian Journal of Geosciences 13, 564. suite of 33 lacustrine source rocks (Pr/Ph ranging from 0.29 to 0.84) from the Songliao Basin with uniform organic matter input have been examined to explore the 17α(H)-diahopane and 18α(H)-neohopane series distribution. The absolute concentrations of 17α(H)-diahopane and 18α(H)-neohopane were determined. In addition, an immature lacustrine source rock was chosen to conduct a thermal simulation experiment to further study the relationship between these components and maturity. Analysis results of geological samples show that the absolute concentrations of 17α(H)-diahopanes have an excellent correlation with 18α(H)-neohopanes, whereas the relative abundance of two series of components exhibited a general correlation. Thermal simulation experiment results show that low absolute concentration and relative abundance of 17α(H)-diahopanes and 18α(H)-neohopanes are presented from low-maturity to high-maturity. However, high absolute concentration and relative abundance are merely distributed near the oil-generative peak. Moreover, with increasing of maturity, the absolute concentrations of both 17α(H)-diahopanes and 18α(H)-neohopanes display an initial increase and a following decrease. Interestingly, the relative abundances of 17α(H)-diahopanes and 18α(H)-neohopanes demonstrate an initial increase and a following decrease with maturity before the oil-generative peak, and then, the ratios display a finally gradual increase with increasing maturity. It suggested that the ratios of rearranged hopanes to hopanes could act as maturity parameter at the high maturity.Zhang, P., Celia, M.A., Bandilla, K.W., Hu, L., Meegoda, J.N., 2020. A pore-network simulation model of dynamic CO2 migration in organic-rich shale formations. Transport in Porous Media 133, 479-496. attractive aspect of CO2 sequestration in shale formations is the preferential adsorption of CO2 compared to methane, which may provide enhanced methane production as well as sequestration of carbon dioxide. In this work, a comprehensive theoretical model of CO2 migration at the pore scale is developed to study CO2 migration properties in organic-rich shale formations. The proposed model takes into account dynamic competitive adsorption between CO2 and CH4, slip-flow effects due to the nanometer range of pore sizes, and pore-size changes due to adsorption. Because of the high pressure and temperature, the injected CO2 is in supercritical phase. Pore bodies in the shale matrix are irregular in shape, with roughness along pore wall. The structure of pore body affects the amount of surface areas and associated number of adsorption sites, and hence, a shape factor is proposed in this work to consider the irregularity of pore structure in shale matrix. The sorption of CO2 leads to an apparent retardation of the migration of CO2, which is quantified in this work. The developed pore-network model is extended to consider the impacts of different spatial distributions of the organic materials within the shale matrix.Zhang, S., 2020. The relationship between organoclastic sulfate reduction and carbonate precipitation/dissolution in marine sediments. Marine Geology 428, 106284. fluid sulfate, calcium and magnesium concentrations in ocean drilling sites 981–984, 925–929 and 803–807 are modeled to estimate the rates of sulfate reduction and carbonate precipitation/dissolution. These sites represent scenarios where the sulfate reduction rate is high, moderate, and low. Results show that the rate of carbonate precipitation decreases with decreasing sulfate reduction rate. When sulfate reduction rate is sufficiently low carbonate minerals dissolve. Sulfate reduction produces H+ and bicarbonate which compete in driving carbonate minerals to dissolve or precipitate. The results suggest that the carbonate reactions are mainly driven by the produced H+ when sulfate reduction rate is low, and by the produced bicarbonate when the sulfate reduction rate is high.Zhang, T., Shi, X.-C., Ding, R., Xu, K., Tremblay, P.-L., 2020. The hidden chemolithoautotrophic metabolism of Geobacter sulfurreducens uncovered by adaptation to formate. The ISME Journal 14, 2078-2089. Fe(III)-reducing Geobacter species including the model Geobacter sulfurreducens are thought to be incapable of carbon dioxide fixation. The discovery of the reversed oxidative tricarboxylic acid cycle (roTCA) for CO2 reduction with citrate synthase as key enzyme raises the possibility that G. sulfurreducens harbors the metabolic potential for chemolithoautotrophic growth. We investigate this hypothesis by transferring G. sulfurreducens PCA serially with Fe(III) as electron acceptor and formate as electron donor and carbon source. The evolved strain T17-3 grew chemolithoautotrophically with a 2.7-fold population increase over 48?h and a Fe(III) reduction rate of 417.5?μM?h?1. T17-3 also grew with CO2 as carbon source. Mutations in T17-3 and enzymatic assays point to an adaptation process where the succinyl-CoA synthetase, which is inactive in the wild-type, became active to complete the roTCA cycle. Deletion of the genes coding for the succinyl-CoA synthetase in T17-3 prevented growth with formate as substrate. Enzymatic assays also showed that the citrate synthase can perform the necessary cleavage of citrate for the functional roTCA cycle. These results demonstrate that G. sulfurreducens after adaptation reduced CO2 via the roTCA cycle. This previously hidden metabolism can be harnessed for biotechnological applications and suggests hidden ecological functions for Geobacter.Zhang, W., Chen, W., Wang, T., Yang, Y., 2020. A self-similarity transport model of gas desorption inside high maturity shale under thermal enhanced conditions. Journal of Natural Gas Science and Engineering 81, 103471. stimulation methods have been investigated to enhance gas extraction from the high maturity shale recently. In this paper, a Longmaxi shale core sample, with vitrinite reflectance?=?2.8%, was selected for canister tests to investigate the gas desorption process first at 55?°C and then switched to 110?°C. A mathematical model (self-similarity) was proposed to mimic the gas decaying process in nano-sized pore system. Gas adsorption/desorption incorporated advection and Knudsen flow were considered in this model. For high Knudsen number flow, the effective diffusion coefficient of the gas in the model was assumed to be a power law of density gradient. From the experiment, when heating temperature was raised from 55?°C to 110?°C, more adsorbed gas started desorbing to the porous media. It was found that the gas production rate increased significantly (20 times) and the cumulative gas production also raised considerably (11 times). By selecting an appropriate exponent m for effective diffusion coefficient, the gas production rate decayed as 1/√t at 55?°C and declined as 1/t2 at 110?°C, which fit well with experimental data. The scaling results indicated that Knudsen flow was the dominant source of the gas flow in the whole heating process. In conclusion, Knudsen flow is the dominant gas transport form during the heating process. Thermal stimulation can significantly promote gas production rate. Moreover, the developed mathematical model can well predict the gas production rate in the heating process.Zhang, W., Xiao, S., Xie, H., Liu, J., Lei, D., Lorke, A., 2020. Diel and seasonal variability of methane emissions from a shallow and eutrophic pond. Biogeosciences Discussions 2020, 1-40. play a critical role in biogeochemical carbon cycling and have been identified as hot spots of methane (CH4) emission. Yet, most existing studies focused on ponds in the boreal zone and current estimates of the relevance of ponds in global CH4 budgets as well as knowledge of the environmental factors regulating their emissions are poorly constrained. Both nutrient concentration and temperature can potentially alter CH4 dynamics in shallow ponds, but there are still few investigations into the response of CH4 emission to nutrient enrichment and rising temperatures. Here we studied the magnitude and regulation of two CH4 pathways (diffusion and ebullition) from a shallow and eutrophic pond located in the subtropical zone in Central China. Ebullitive fluxes were on average 96.4?mg?CH4?m?2?d?1 and contributed 88.6?% to the total (diffusive?+?ebullition) CH4 emissions. Daily CH4 fluxes were related to daily mean water temperature, with ebullition having a stronger temperature dependence than diffusion (Q10 of 5.52 vs. 2.05). Relationships between temperature and CH4 emission were affected by seasonal variation of the concentration of total phosphorus. The temperature dependence of both ebullitive and diffusive fluxes increased with increasing phosphorous concentration. Our study highlights that increasing eutrophication by anthropogenic impacts and climate warming will increase CH4 emissions from ponds, thus representing a positive feedback mechanism to global warming.Zhang, X., Han, J., Zhang, X., Shen, J., Chen, Z., Chu, W., Kang, J., Zhao, S., Zhou, Y., 2020. Application of Fourier transform ion cyclotron resonance mass spectrometry to characterize natural organic matter. Chemosphere 260, 127458. in the ultra-high-resolution mass spectroscopy lead to a deep insight into the molecular characterization of natural organic matter (NOM). Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) has been used as one of the most powerful tools to decipher NOM molecules. In FTICR-MS analysis, the matrix effects caused by the co-occurring inorganic substances in water samples greatly affect the ionization of NOM molecules. The inherent complexity of NOM may hinder its component classification and formula assignment. In this study, basic principles and recent advances for sample separation and purification approaches, ionization methods, and the evolutions in formula assignment and data exploitation of the FTICR-MS analysis were reviewed. The complementary characterization methods for FTICR-MS were also reviewed. By coupling with other developed/developing characterization methods, the statistical confidence for inferring the NOM compositions by FTICR-MS was greatly improved. Despite that the refined separation procedures and advanced data processing methods for NOM molecules have been exploited, the big challenge for interpreting NOM molecules is to give the basic structures of them. Online share of the FTICR-MS data, further optimizing the FTICR-MS technique, and coupling this technique with more characterization methods would be beneficial to improving the understanding of the composition and property of NOM.Zhang, Y., Hu, Q., Barber, T.J., Bleuel, M., Anovitz, L.M., Littrell, K., 2020. Quantifying fluid-wettable effective pore space in the Utica and Bakken oil shale formations. Geophysical Research Letters 47, e2020GL087896.: Combined (ultra‐) small angle neutron scattering measurements [(U)SANS] and a contrast matching technique were employed to quantify the porosity and pore size distribution from 1 nm to 10 μm and to differentiate accessible (open) pores and inaccessible (closed) pores with respect to organophilic and hydrophilic fluids for two Utica and two Bakken shale samples. The results indicate that around 40–70% of the pores in the Utica oil shales (mixed carbonate mudstone) are accessible to oil, and 34–37% of the pore surfaces are water‐wet. In contrast, the Bakken oil shales (mixed siliceous mudstone and carbonate/siliceous mudstone), which have high total organic carbon contents, have a higher proportion of isolated pore space that is not preferentially wet by oil or water, with less than 36% of the pores accessible to both fluids. In addition, for both formations, pores less than 3 nm in diameter are not oil accessible (organic matter related) but water accessible (clay tactoids related).Plain Language Summary: The economics of shale reservoirs are affected by a steep initial production decline and low overall hydrocarbon recoveries. Shales are characterized by a wide spectrum of nm‐μm‐sized pores with limited accessibility and mixed wettability due to the presence of both fine‐grained minerals and organic matter; this leads to an intertwined relationship between pore size and wettability. This work develops an innovative approach to using (ultra‐) small angle neutron scattering [(U)SANS], along with deuterium labeling of n‐decane and water fluids, to separate oil‐ and water‐accessible and wettable pore space over a wide pore size range of 1 nm to 10 μm in two key U.S. shale oil reservoirs (Utica and Bakken). Our results quantify the proportion of oil‐ or water‐accessible pore volume and size with respect to lithofacies and total organic carbon content. No oil‐accessible pores less than 3 nm in diameter were found in these shales using this method. The approach and findings could help to explain both the slow hydrocarbon movement and steep production decline observed.Zhang, Y., Huck, T., Lique, C., Donnadieu, Y., Ladant, J.-B., Rabineau, M., Aslanian, D., 2020. Early Eocene vigorous ocean overturning and its contribution to a warm Southern Ocean. Climate of the Past 16, 1263-1283. early Eocene (～55?Ma) was the warmest period of the Cenozoic and was most likely characterized by extremely high atmospheric CO2 concentrations. Here, we analyze simulations of the early Eocene performed with the IPSL-CM5A2 Earth system model, set up with paleogeographic reconstructions of this period from the DeepMIP project and with different levels of atmospheric CO2. When compared with proxy-based reconstructions, the simulations reasonably capture both the reconstructed amplitude and pattern of early Eocene sea surface temperature. A comparison with simulations of modern conditions allows us to explore the changes in ocean circulation and the resulting ocean meridional heat transport. At a CO2 level of 840?ppm, the early Eocene simulation is characterized by a strong abyssal overturning circulation in the Southern Hemisphere (40?Sv at 60°?S), fed by deepwater formation in the three sectors of the Southern Ocean. Deep convection in the Southern Ocean is favored by the closed Drake and Tasmanian passages, which provide western boundaries for the buildup of strong subpolar gyres in the Weddell and Ross seas, in the middle of which convection develops. The strong overturning circulation, associated with subpolar gyres, sustains the poleward advection of saline subtropical water to the convective regions in the Southern Ocean, thereby maintaining deepwater formation. This salt–advection feedback mechanism is akin to that responsible for the present-day North Atlantic overturning circulation. The strong abyssal overturning circulation in the 55?Ma simulations primarily results in an enhanced poleward ocean heat transport by 0.3–0.7?PW in the Southern Hemisphere compared to modern conditions, reaching 1.7?PW southward at 20°?S, and contributes to keeping the Southern Ocean and Antarctica warm in the Eocene. Simulations with different atmospheric CO2 levels show that ocean circulation and heat transport are relatively insensitive to CO2 doubling.Zhang, Y., Lin, D.-F., Hao, J., Zhao, Z.-H., Zhang, Y.-J., 2020. The crucial role of bacterial laccases in the bioremediation of petroleum hydrocarbons. World Journal of Microbiology and Biotechnology 36, 116. (EC 1.10.3.2) are a class of metallo-oxidases found in a variety of fungi, plants, and bacteria as well as in certain insects. They can oxidize a wide variety of organic compounds and can be widely applied in many fields, especially in the field of biodegradation and detoxification of environmental pollutants. The practical efficacy of laccases depends on their ability to capture the target substance as well as their catalytic activity, which is related to their catalytic center, substrate selectivity, and substrate tolerance. Over the past few decades, many laccases have been identified in plants and fungi. Concurrently, bacterial laccases have received increasing attention because of their high thermostability and high tolerance to organic compounds. The aim of this review is to summarize the role of bacterial laccases in the bioremediation of petroleum hydrocarbons and to outline the correlation between the molecular structure of the mononuclear T1 Cu center of bacterial laccases and their substrate preference.Zhang, Y., Tang, D., Li, S., Cao, D., Liu, J., 2020. Deciphering multiple controls on mesopore structural heterogeneity of paralic organic-rich shales: Pennsylvanian–Lower Permian Taiyuan and Shanxi formations, Weibei Coalfield, southwestern North China. Journal of Petroleum Science and Engineering 195, 107613. study investigates the various factors that affect the mesopore structural heterogeneity of paralic organic-rich shales in the Pennsylvanian–Lower Permian Taiyuan and Shanxi formations, in the Weibei Coalfield of southwestern North China. This assessment is based on an integrated analysis of facies, mineralogical, petrographic, geochemical, and low-temperature N2 adsorption data. Facies analysis leads to the recognition of five facies associations that record the following depositional systems: medial epeiric shelf (FA1), proximal epeiric shelf (FA2), open-coast tidal flat (FA3), river-dominated delta (FA4), and coastal lake (FA5). Shales from the different depositional facies are classified into five different lithotypes: fossiliferous calcareous shale (FCS), fossiliferous mixed shale (FMS), argillaceous siliceous shale (ASS), illite-dominated argillaceous shale (IAS), and kaolinite-dominated argillaceous shale (KAS). FCS appears to be confined to the carbonate shelf in the medial epeiric shelf. Its mesopore structure is severely damaged by extensive micritization and local micrite recrystallization, and only a few plate-like large mesopores (4.34–50 nm) between the carbonate grains survived. FMS is typical of seaward flank deposits of the proximal epeiric shelf. Although abundant calcite cements are formed by the calcification of aragonite shells, FMS still has a few inkbottle-shaped mesopores due to the input of terrigenous clastic sediment. IAS is widely developed in the open-coast supratidal marsh due to volcanic ash kaolinization and kaolinite illitization. Illite-smectite group clays determine the presence of fine mesopores (3–4.34 nm), which are the main contributors to the specific surface area. Thus, IAS has the most abundant homogeneous fine mesopores, as well as the largest specific surface area and pore volume. Conversely, KAS is formed in the delta-plain interdistributary swamp and has a dense structure. ASS is mainly composed of terrigenous clasts and can be formed in multiple environments. Silt-sized brittle minerals determine the number of large mesopores, which are conducive to the total pore volume. Therefore, ASS has a bimodal pore size distribution, as well as medium pore structure parameters and fractal dimensions. This study contributes to a better understanding and prediction of the mesopore structure evolution of organic-rich shales that formed in various paralic sub-environments.Zhao, X., Zhou, L., Pu, X., Shi, Z., Han, G., Wu, J., Han, W., Zhang, W., Gao, H., Ma, J., Wang, H., 2020. Geological characteristics and exploration breakthrough of shale oil in Member 3 of Shahejie Formation of Qibei subsag, Qikou sag Acta Petrolei Sinica 41, 643-657. fine-grained sediments are developed in Member 3 of Shahejie Formation of Qibei subsag of Qikou sag, with good source rock quality and rich in shale oil resources. However, the corresponding research is still in the early stage. As stimulated by the industrial development of lacustrine shale oil in Member 2 of Kongdian Formation of Cangdong sag, it is inevitable to implement the exploration prospects of fine-grained sediments. In order to explore the geological characteristics and exploration potential of shale oil in Member 3 of Shahejie Formation of Qibei subsag, based on the cores, analytical tests, logging data and logging data of the wells such as F39X1 and QY10-1-1, a comprehensive study is carried out on the geological characteristics, shale oil types and enrichment patterns of the shale strata in Member 3 of Shahejie Formation, and the spatial distribution of sweet spots. There are various mineral compositions and rock types in Member 3 of Shahejie Formation of Qibei subsag, mainly including calcareous-dolomitic shale, felsic shale, hybrid shale, micritic dolomite, sparry bioclastic dolomite, and siltstone. The total organic carbon (TOC) content of source rocks is mainly distributed between 1% and 3%, dominated by type Ⅱ kerogen, and the vitrinite reflectance (Ro) is generally higher than 0.7%. The reservoir spaces mainly include intergranular pores, intercrystalline pores, biological cavity pores, organic pores, bedding fractures, and structural (or microstructural) fractures. The shale oil presents obvious crossover effect (with an average oil saturation index of 116.3 mg/g), as well as good fluorescence effect. This study identifies two types of shale oil, i.e., monolayer type and interbedded type, in Member 3 of Shahejie Formation in Qibei subsag, constructs two enrichment patterns, i.e., high-TOC retention-type and low-TOC migration-type shale oil, and establishes the quantitative evaluation methods and standards of sweet spot based on multiple parameters such as oil saturation index, TOC and brittleness index. For the horizontal well QY10-1-1 deployed in the sweet spot, the initial oil production is calculated to be 103.5 t/d; it is expected to form a new field with the increasing reserves of 100 million tons. It is confirmed by the exploration discovery that the fine-grained rock section of Member 3 of Shahejie Formation in Qikou sag has good exploration potential for shale oil.Zheng, H., Kim, K., Kravchenko, A., Rivers, M., Guber, A., 2020. Testing Os staining approach for visualizing soil organic matter patterns in intact samples via X-ray dual-energy tomography scanning. Environmental Science & Technology 54, 8980-8989. with in situ visualization of nonparticulate organics in porous materials limit understanding and modeling processes of transport, decomposition, and storage of organic compounds. In particular, it impedes deciphering the mechanisms driving accumulation and protection of soil organic matter (SOM), processes crucial for sustaining soil fertility and mitigating effects of global climate change. A recently proposed method of staining soil organics by OsO4 vapors with subsequent dual-energy X-ray computed microtomography scanning (μCT) offers new opportunities to visualize SOM within intact soil matrix. Our objective was to test the method’s performance in staining different organic materials located in media with contrasting pore characteristics: (1) roots of switchgrass (Panicum virgatum L.), either placed within fine and coarse sands or grown within soil microcores, (2) biochar fragments, and (3) soils with relatively low and high C contents. We found that the method was effective in staining organic materials of root origin and the organics associated with fine soil particles, but not the biochar. The estimated percent of total C that reacted with OsO4 vapors ranged from 0.7% in plant roots to 3.2% in sand-free fraction of the high C soil and was only 0.2% in the studied biochar. Total soil C and Os concentrations were strongly linearly related, suggesting a potential for future method development. However, we would recommend caution when interpreting the results in cases when gas diffusion through the soil matrix is limited.Zheng, R., Fan, Z., Li, X., Negahban, S., 2020. Phase behavior of high-pressure CH4-CO2 hydrates in NaCl solutions. Fuel 280, 118549. the phase behavior of CH4-CO2 hydrates formed in NaCl solutions is important for gas recovery from hydrate reservoirs, CO2 sequestration, and flow assurance. The observations of CH4-CO2 hydrates formed in NaCl solutions are limited at high-pressure and high-temperature conditions. In this work, a high-pressure experimental apparatus is built to investigate the phase behavior of CH4-CO2 hydrates. The interfacial phenomenon is observed during hydrate formation and dissociation. The phase boundary of CH4-CO2 hydrates is determined by using the isochoric pressure-search method with pressure above 10 MPa. A novel theoretical model is developed to calculate the phase boundary pressure of hydrates by implementing a modified PR EoS for the fluid phases, the van der Waals-Platteeuw model for the hydrate phase, and the Pitzer model for the effect of ions. It is revealed that the roughness of water–gas interface is greatly increased at the initial hydrate formation stage due to the occurrence of fine pillars at the interface, which is explained by two hypotheses, i.e., the non-equilibrium state of gas and water phases and the non-uniform lateral growth of hydrates at the interface. The roughness decreases as time goes by during hydrate formation owing to the thickness growth of the hydrate film. The deviation of the calculated phase boundary pressure from the 86 collected experimental data points of CH4-CO2 hydrates formed in pure water is 3.7%, and is 5.3% for the 24 collected phase boundary data points of CH4-CO2 hydrates formed in the NaCl solutions, which proves the reliability of the newly developed model. The measured phase boundary data points of CH4-CO2 hydrates formed in NaCl solutions in this work extend the phase boundary pressure up to 61.99 MPa and the temperature to 295.09 K, which have filled the blank of the database in the high-pressure and high-temperature region. The deviations of the calculated phase boundary pressure from these two groups of measured ones are 8.9% and 6.2% respectively.Zheng, S., Yao, Y., Elsworth, D., Liu, D., Cai, Y., 2020. Dynamic fluid interactions during CO2-ECBM and CO2 sequestration in coal seams. Part 2: CO2-H2O wettability. Fuel 279, 118560. addition to CO2-CH4 interactions (Part 1), the success of CO2 enhanced coalbed methane (CO2-ECBM) and geological sequestration are significantly affected by the CO2-H2O wettability. Wettability controls both gas desorption and transport and is influenced by injection pressure, reservoir temperature and the state of water that is present – as either adsorbed- or free-water. Dynamic changes in wettability remains poorly constrained – due to the innate difficulty and invasive nature of conventional measurements (e.g., captive gas bubble and pendent drop tilted plate methods). In part 2, we use nuclear magnetic resonance (NMR) as a non-invasive method to explore the mechanisms of these factors (pressure, temperature, water-state) on CO2-H2O wettability during CO2-ECBM. Results for contrasting subbituminous coal and anthracite show that the CO2 wettability of coals significantly increases with increasing CO2 injection pressure up to 5 MPa before stabilizing to a limiting value. This suggests that the most economically-suitable injection pressure is ~5 MPa. CO2 wettability also increases with a decrease in temperature suggesting that shallower reservoirs may be marginally improved in this trend. Additionally, the presence of non-adsorbed water in coals significantly reduces both the sensitivity of CO2 wettability to pressure and the absolute magnitude of wettability relative to the case where free-water is absent. Thus, draining free-water from the reservoir will serve the dual purposes of both increasing gas transport and the potential for desorption from the perspective of CO2-H2O wettability. The far-reaching results in this study, together with the companion paper (Part 1) are significant for evaluating CO2-ECBM improvement both in enhancing methane recovery and CO2 utilization in coals.Zheng, S., Yao, Y., Elsworth, D., Liu, D., Cai, Y., 2020. Dynamic fluid interactions during CO2-enhanced coalbed methane and co2 sequestration in coal seams. Part 1: CO2–CH4 interactions. Energy & Fuels 34, 8274-8282. injection of CO2 into coalbed methane (CBM) reservoirs to enhance methane recovery has a second desirable benefit in simultaneously sequestering CO2. However, the real-time dynamic evolution of native adsorbed and rejected non-adsorbed methane during the process of CO2-enhanced coalbed methane (CO2-ECBM) production remains poorly constrained as a result of the nonlinear and hysteretic response of both CO2–CH4 interactions (part 1) and CO2–H2O wettability (part 2) of the coal under recreated reservoir conditions. In part 1, we apply calibrated nuclear magnetic resonance (NMR) to explore mechanisms of methane desorption and CO2 replacement during multiple cycles of CO2-ECBM flooding under recreated in situ conditions. Results for contrasting sub-bituminous coal and anthracite indicate that the adsorbed methane sweep efficiency is improved by ～16–26% with a single injection of CO2 over mere in situ desorption. Furthermore, CO2–CH4 displacement rates evolve during each CO2 injection cycle, first declining rapidly and then stabilizing with a long desorptive tail. Importantly, the cumulative methane sweep efficiency increases monotonically with successive cycles of CO2 injection, albeit at a reducing incremental efficiency, identifying the utility of cyclic CO2-ECBM as an effective method in both CO2 sequestration and enhanced gas recovery. Observed ratios of CO2 sorption capacities to CH4 recovery are 5.0 and 2.2 for sub-bituminous coal and anthracite, respectively, demonstrating an elevated potential for CO2 sequestration in sub-bituminous coals and more favorable CO2-ECBM recovery in anthracite, per unit mass of CO2 injected.Zheng, S., Yao, Y., Elsworth, D., Wang, B., Liu, Y., 2020. A novel pore size classification method of coals: Investigation based on NMR relaxation. Journal of Natural Gas Science and Engineering 81, 103466. magnetic resonance (NMR) severs as a nondestructive and relative new technique that has been widely used in characterizing reservoir fluids and pore size distribution (PSD) of coals. Conventionally, pore fluids in coals are classified into movable fluid and irreducible fluid based on a single NMR T2 cutoff value (T2C). However, the single NMR T2 cutoffs model has some apparent defects in pore fluid/size classification, and few researches have reported the limitation of the single T2 cutoffs model. In contrast, the dual T2 cutoffs model may provide an accurate quantified model to classify different pore fluid types in coals. In this study, fifteen coal samples with different ranks were conducted in systematic NMR and centrifugal experiments to investigate the characteristics of pore fluid typing and PSD. Results show that when tried applying the single NMR T2 cutoffs model to classify the pore fluid typing, there are still some movable fluids when T2 < T2C. At the same time, when T2 > T2C, there is remaining some irreducible fluid in pores after high pressure centrifugal experiments. These results indicated the limited application of single NMR T2 cutoffs model in pore fluid classification. By introducing a novel pore fluid classification method (i.e. the dual T2 cutoffs model), a typical T2 spectrum under fully-saturated condition, the absolute irreducible fluid T2 cutoffs (T2C1) and absolute movable fluid T2 cutoff (T2C2) can re-divide the pore fluid typing of coal into three types: absolute irreducible fluid (T2 < T2C1), partial movable fluid (T2C1 < T2 < T2C2), and absolute movable fluid (T2 > T2C2). The results show that the T2C1 is in the range of 0.10–0.32 ms, while the T2C2 has a wider range from 36.12 ms to 89.07 ms. Finally, a conceptional model were proposed to clarify a full-scale PSD classification that includes the absolute irreducible fluid pores, partial movable fluid pores and absolute movable fluid pores. The model established in this study, can also be applicable for other rock types (e.g., sandstones, carbonates and shales).Zheng, T., Ma, X., Pang, X., Zheng, D., Wang, W., Wang, X., Zhang, K., Wang, K., Ma, K., 2020. Hydrocarbon generation and expulsion features of the Upper Triassic Xujiahe Formation source rocks and their controlling effects on hydrocarbon accumulation in the Sichuan Basin, Central China. Geological Journal 55, 4977-4996. the features of the hydrocarbon generation and expulsion of the Upper Triassic Xujiahe Formation (T3x) source rocks is important to properly guide petroleum exploration in the Xujiahe Formation in the Sichuan Basin. Based on mass balance, the hydrocarbon generation and expulsion from the T3x source rocks are characterized in this paper through a method (i.e., hydrocarbon generation potential index using pyrolysis data) different from that used in previous studies. The threshold and peak of hydrocarbon expulsion are determined to be R o = 0.9% and 1.15%, respectively. The amounts of hydrocarbon generated and expelled in the T3x source rocks are 4,525.5 × 108 and 2,420.5 × 108 t, respectively. Moreover, three hydrocarbon expulsion regions T3x have been identified in the Sichuan Basin. On the basis of the hydrocarbon generation and expulsion features of the source rocks and the distribution of the oil‐and‐gas reservoirs, the quantitative model of the hydrocarbon accumulation probability under the control of the T3x source rock is established via single‐factor regression analysis. The predictions obtained through this analysis show that the favourable oil‐and‐gas exploration areas in the Xujiahe Formation are distributed in the Qionglai, Chengdu, and Deyang regions, as well as in the west of Yilong region. Further, the results show that 78% of the discovered oil‐and‐gas reservoirs are located in the predicted favourable and relatively favourable oil‐and‐gas exploration areas.Zherebker, A., Lechtenfeld, O.J., Sarycheva, A., Kostyukevich, Y., Kharybin, O., Fedoros, E.I., Nikolaev, E.N., 2020. Refinement of compound aromaticity in complex organic mixtures by stable isotope label assisted ultrahigh-resolution mass spectrometry. Analytical Chemistry 92, 9032-9038. transform ion cyclotron resonance mass spectrometry (FTICR MS) provides a unique opportunity for molecular analysis of natural complex mixtures. In many geochemical and environmental studies structure–propertry relations are based solely on the elemental compositional information. Several calculated parameters were proposed to increase reliability of structural attribution, among which aromaticity indices (AI and AImod) are widely used. Herein, we applied a combination of selective labeling reactions in order to obtain direct structural information on the individual components of lignin-derived polyphenolic material. Carboxylic (COOH), carbonyl (C═O), and hydroxyl (OH) groups were enumerated by esterification, reducing, and acetylation reactions, respectively, followed by FTICR MS analyses. Obtained information was enabled to constrain aromaticity accounting for the carbon skeleton only. We found that actual aromaticity of components may be both higher or lower than approximated values depending on the abundance of COOH, C═O, and OH groups. The results are of importance for the geochemical community studying terrestrial NOM with structural gradients.Zhou, L., Mijiddorj, E., 2020. Stories behind the fortress: Stable isotope analysis and 14C dating of soldiers' remains from the Bayanbulag site, Mongolia. Archaeometry 62, 863-874. carbon and nitrogen isotope analysis of 15 individuals buried closed to Bayanbulag site or the Shouxiangcheng fortress in southern Mongolia revealed complex dietary features. Only one individual had a diet similar to that of the pastoral population in northern China, while the others, who had varying carbon isotope values and low nitrogen values, might have been from different agricultural areas. 14C dating results suggest that the earliest interment could be much earlier than the building of Shouxiangcheng fortress recorded in Han texts. Analysis of the burial arrangement further confirmed that these deceased were not buried at the same time.Zhou, S., Yan, D., Tang, J., Pan, Z., 2020. Abrupt change of pore system in lacustrine shales at oil- and gas-maturity during catagenesis. International Journal of Coal Geology 228, 103557. of the biggest challenges in evaluating the transport and storage properties of shales is understanding how the pore structure and network evolve in the same stratigraphic shale during catagenesis. Using a combination of CO2 adsorption, mercury intrusion porosimetry, as well as scanning electron microscopy, we have described the evolution and the abrupt changes (jump) of pore characteristics in lacustrine shale at oil and gas maturation. With an increase maturity, our sample set exhibited abrupt changes in porosity-related characteristics. Porosity and surface areas presented a decline and then an increase, and a jump occurred due to hydrocarbon generation, with the minimum value in late maturity (i.e. vitrinite reflectance of ~1.3%). These changes were accompanied by corresponding changes in pore-size distributions, surface area percentage, and multi-scale pores volumes. The trends in porosity variation were related to different organic matter and mineral contents in our samples, to some extent, with the degree of maturation being the dominant influence. We found that inorganic pores were the main contributor to the porosity of less mature shales, while porosity in gas-mature shales was dominated by organic matter pores. In this work, we showed that organic matter transformation was a centric component of pore evolution. Our findings may fill significant gaps in understanding and predicting pore development, with respect to the maturity of lacustrine shales.Zhu, B., Kübler, M., Ridoli, M., Breitenstein, D., Schroth, M.H., 2020. Quantity and distribution of methane entrapped in sediments of calcareous, Alpine glacier forefields. Biogeosciences 17, 3613-3630. from many well-known sources, the greenhouse gas methane (CH4) was recently discovered entrapped in the sediments of Swiss Alpine glacier forefields derived from calcareous bedrock. A first study performed in one glacial catchment indicated that CH4 was ubiquitous in sediments and rocks and was largely of thermogenic origin. Here, we present the results of a follow-up study that aimed at (1) determining the occurrence and origin of sediment-entrapped CH4 in other calcareous glacier forefields across Switzerland and (2) providing an inventory of this sediment-entrapped CH4, i.e., determining the contents and total mass of CH4 present, and its spatial distribution within and between five different Swiss glacier forefields situated on calcareous formations of the Helvetic nappes in the Central Alps.Sediment and bedrock samples were collected at high spatial resolution from the forefields of Im Griess, Griessfirn, Griessen, Wildstrubel, and Tsanfleuron glaciers, representing different geographic and geologic regions of the Helvetic nappes. We performed geochemical analyses on gas extracted from sediments and rocks, including the determination of CH4 contents, stable carbon-isotope analyses (δ13CCH4), and the determination of gas-wetness ratios (ratio of CH4 to ethane and propane contents). To estimate the total mass of CH4 entrapped in glacier-forefield sediments, the total volume of sediment was determined based on the measured forefield area and either literature values of mean sediment thickness or direct depth measurements using electrical resistivity tomography.Methane was found in all sediments (0.08–73.81??g?CH4?g?1 dry weight) and most rocks (0.06–108.58??g?CH4?g?1) collected from the five glacier forefields, confirming that entrapped CH4 is ubiquitous in these calcareous formations. Geochemical analyses further confirmed a thermogenic origin of the entrapped CH4 (average δ13CCH4 of sediment of ?28.23 (±?3.42)?‰; average gas-wetness ratio of 75.2 (±?48.4)). Whereas sediment-entrapped CH4 contents varied moderately within individual forefields, we noted a large, significant difference in the CH4 content and total CH4 mass (range of 200–3881?t CH4) between glacier forefields at the regional scale. The lithology and tectonic setting within the Helvetic nappes appeared to be dominant factors determining rock and sediment CH4 contents. Overall, a substantial quantity of CH4 was found to be entrapped in Swiss calcareous glacier forefields. Its potential release and subsequent fate in this environment is the subject of ongoing studies.Zhu, K., Song, X., Lu, F., Jiang, B., Wang, C., Yang, G., Chen, Z., 2020. Geological controls on coalbed methane accumulation and optimisation strategy for gas productivity: a case study in eastern Ordos Basin, China. International Journal of Oil, Gas and Coal Technology 24, 573-592. conditions can significantly affect the coalbed methane (CBM) production, which is accomplished by reducing the gas partial pressure in the coal seam. This can be achieved by pumping the formation water or gas injection. In this study, the Baode region is selected to study the drainage conditions and production characteristics on the early stage of CBM production. The temporal trends of water production, wellhead pressure and gas production have been analysed. Results show that the favourable burial depth for CBM accumulation between 500 and 700 m. Sandy mudstone and mudstone are beneficial to CBM preservation. The wellhead pressure should be maintained between 0.4 MPa and 1.0 MPa, and the optimal range of wellhead pressure lies between 0.5 and 0.8 MPa for stable production. The gas production increases with increased water production when the wellhead pressure has become progressively stable in the middle phase of early stage.Zhu, Y., Liu, H., Xu, Y., Hu, C., Zhao, C., Cheng, J., Chen, X., Zhao, X., 2020. Preparation and characterization of coal-pitch-based needle coke (Part III): The effects of quinoline insoluble in coal tar pitch. Energy & Fuels 34, 8676-8684. coal tar pitch is often used to produce high-quality needle coke. Its basic properties [such as fa value, β resin, and quinoline insoluble (QI) content] significantly affect the quality of the resulting needle coke. Refined pitch with fa and β-resin values in the 0.95–0.98 and 13–16% ranges, respectively, is considered an excellent raw material for this purpose. The influence of QI content on the characteristics of coal-based needle coke is still not fully clarified in the literature. To analyze how QI content affects coal-based needle coke properties, this work used 10 different kinds of coal tar pitch (refined from the same source) with different QI contents for the needle coke production. We thoroughly analyzed optical microstructure and crystalline sizes, surface morphology and microstrength, true density, and coefficient of thermal expansion (CTE) of the resulting products. The high-temperature coal tar pitch with the QI content of <0.8% was a preferable raw material to obtain superior needle coke; it possessed higher density and microstrength, lower CTE, and graphitized more easily than cokes with other parameters. ................
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