LAB: WATER QUALITY TESTING



LAB: WATER QUALITY TESTING INTRODUCTION More and more people are realizing that we need to find better ways to share our world’s natural resources with each other and with other species to ensure that the planet can support life in the future. By allowing poison in our waters, we are slowly drinking it ourselves. Everything we do affects our water. We are beginning to see how important each of us is to making the world a better place to live, no matter what kind of work we do or how intelligent society says we are. There are two general methods of monitoring water quality: chemical monitoring and biological monitoring. Chemical monitoring provides good data on what was happening at the instant that it is measured. In this lab, we will be testing for pH, temperature, turbidity, nitrates, phosphates, and dissolved oxygen. Biological monitoring can provide a longer term picture. Indicator organisms respond to certain conditions consistently and the structure of the macroinvertebrate community is a reliable indicator of water quality. MATERIALS ThermometerCompass Vandorn water samplerRope La Motte Nitrates test kit La Motte Phosphates test kitLa Motte Dissolved oxygen test kit La Motte pH test kit La Motte turbidity test kit transparency tube Coliscan Easygel (E. coli) kit La Motte Carbon dioxide test kitLa Motte La Motte Hardness test kitSilica test kitVerneir conductivity probe Dip net Vials PROCEDURE Nitrate: Fill sample bottle with sample water. Fill one test tube to the 2.5 ml line with water from the sample bottle. Dilute to the 5 ml line with Mixed Acid Reagent (V-6278). Cap and mix. Wait 2 minutes. Use the 0.1 g spoon (0699) to add one level measure (avoid any excess) of Nitrate Reducing Reagent (V-6279). Cap and invert gently 50-60 times in one minute. Wait 10 minutes. Insert test tube into Nitrate-N Comparator (3109). Match sample color to a color standard. Record as ppm Nitrate as Nitrate Nitrogen. Convert this number to ppm Nitrate by multiplying it by 4.4. Total Phosphate: Fill test tube to the 10 ml mark with sample water. Use 1.0 ml pipet with to add 1.0 ml of Phosphate Acid Reagent.Cap and mix. Use the 0.1 g spoon to add one level measure of Phosphate Reducing Agent. Cap and mix until dissolved. Wait 5 minutes. Remove stopper from test tube. Place tube in Phosphate Comparator with Axial Reader. Match sample color to a color standard. Record as ppm Orthophosphate. Dissolved Oxygen Steps 1-7 must be completed in the field. The remainder of the procedure can be completed the following day in the lab. Fill the water sampling bottle by submerging it and allowing it to fill completely. Tap the sides of the bottle to dislodge any air bubbles and replace the cap while the bottle is still submerged. Make sure that there are not air bubbles trapped inside the bottle (this will affect your measurement). Add 8 drops of Manganous Sulfate Solution (4167). Add 8 drops of Alkaline Potassium Iodide Azide (7166). Cap and mix. Allow precipitate to settle. Use the 1.0 g spoon to add Sulfamic Acid Powder or add 8 drops of sulfuric acid, 1:1. Cap and mix until the reagent and precipitate dissolve. At this point the sample has been “fixed” and contact between the sample and the atmosphere will not affect the test result. Fill titration tube to the 20 ml line with the fixed sample. Fill titrator with Sodium Thiosulfate, 0.025N. To accomplish this, first depress the plunger of the titrator to expel any air. Then, insert the titrator into the plug in the top of the 0.025N Sodium Thiosulfate titrating solution. Invert the bottle and slowly withdraw the plunger until the bottom of the plunger is opposite the zero mark on the scale. If small air bubbles appear in the titrator barrel, expel them by partially filling the barrel and pumping the titration solution back into the reagent container. Repeat until the bubble disappears. Insert the tip of the titrator into the opening of the titration tube cap. Slowly depress the plunger to dispense the titrating solution until the yellow-brown color changes to a very pale yellow. Gently swirl the tube during the titration to mix the contents. Titrate until sample color is pale yellow. Add 8 drops of Starch Indicator. The sample should turn blue. Continue titration until blue color just disappears and solution is colorless. Record the test result where the titrator tip meets the scale. Read the result in ppm Dissolved Oxygen. Each minor division on the titrator scale equals 0.2 ppm. pH: 1. Fill the test tube to the 5.0 ml line with sample water. 2. Add 10 drops of reagent (WR Ind). 3. Cap and mix. 4. Insert test tube into Octet Comparator. Match the sample color to a color standard and record the pH. For optimum color comparison, the comparator should be positioned between the operator and a light source, so that the light enters through the special light-diffusing screen in the back of the comparator. Avoid viewing the comparator against direct sunlight or an irregularly lighted background. Turbidity: This test is made by comparing the turbidity of a measured amount of the sample with an identical amount of turbidity-free water containing a measured amount of standardized turbidity reagent. The readings are made by looking down through the column of liquid at a black pie shape. It turbidity is present, it will interfere with the passage of light through the column of liquid. Small amounts of turbidity will cause a “blurring” of the black pie shape in the bottom of the tube. Large amounts of turbidity may provide sufficient “cloudiness” so that it is not possible to see the black pie shape when looking down through the column. Any color that may be present in the sample should be disregarded. This determination is concerned only with the haziness or cloudy nature of the sample. Fill one Turbidity Column to the 50 ml line with the sample water. If the black shape on the bottom of the tube is not visible when looking down through the column of liquid, pour out a sufficient amount of the test sample so that the tube is filled to the 25 ml line. Fill the second Turbidity Column with an amount of turbidity-free water that is equal to the amount of sample being measured. Distilled water is preferred; however, clear tap water may be used. This is the “clear water” tube. Place the two tubes side by side and note the difference in clarity. If the black shape is equally clear in both tubes, the turbidity is zero. If the black dot in the sample tube is less clear, proceed to step 4. Shake the Standard Turbidity Reagent (7520) vigorously. Add 0.5 ml to the “clear water” tube. Use the stirring rod to stir contents of both tubes to equally distributed turbid particles. Check for the amount of turbidity by looking down through the solution at the black shape. If the turbidity of the sample water is greater than that of the “clear water”, continue to add Standard Turbidity Reagent in 0.5 ml increments to the “clear water” tube, mixing after each addition until the turbidity equals that of the sample. Record the total amount of Turbidity Reagent added. Each 0.5 ml addition to the 50 ml size sample is equal to 5 Jackson Turbidity Units (JTUs). If a 25 ml sample size is used, each 0.5 ml addition of the Standard Turbidity Reagent is equal to 10 JTUs. Rinse both tubes carefully after each determination. Temperature: 1. Submerge the thermometer beneath the water for 60 seconds before reading. 2. Record your answer in degrees Celsius. Coliforms and E. coliEither collect your water sample in a sterile container and transport the water back to the test site, or take a measured water sample directly from the source and place directly into the bottle of Coliscan Easygel.?Water samples kept longer than 1 hour prior to plating, or any Coliscan Easygel bottle that has had sample placed into it for transport longer than 10 minutes, should be kept on ice or in a refrigerator until plated.Label the petri dishes with the appropriate sample information. A permanent marker or wax pencil will workSterilely transfer water from the sample containers into the bottles of Coliscan Easygel (Consult the following table for rough guidelines for inoculum amount). Swirl the bottles to distribute the inoculum and then pour the medium/inoculum mixtures into the correctly labeled petri dishes. Place the lids back on to the petri dishes. Gently swirl the poured dish until the entire dish is covered with liquid (but be careful not to splash over the side or on the lid).Inoculation of Coliscan EasygelThe dishes may be placed right-side-up directly into a level incubator or warm level spot in the room while still liquid. Solidification will occur in approximately 45 minutes.Incubate at 35 ? C (95 ? F) for 24 hours, or at room temperature for 48 hours. (see Comments on incubation.Inspect the dishes.Count all the purple colonies on the Coliscan dish (disregard any light blue, blue-green or white colonies), and report the results in terms of?E. coli?or Fecal Coliform per mL of water.Note: To report in terms of E. coli or Fecal Coliform per 100 mL of water, first find the number to multiply by:Divide 100 by the number of mL that you used for your sample.Multiply the count in your plate by the result obtained from #1.e.g. For a 3 mL sample, 100 / 3 = 33.3. So 4 E. coli colonies multiplied by 33.3 will be equal to 133.2 E. coli per 100 mL of water.Count all the pink and purple colonies on the Coliscan dish (disregard any light blue, blue-green or white colonies) and report the results in terms of coliforms per mL of water.Do one of the following prior to disposal in normal trash:Place dishes and Coliscan bottles in a pressure cooker and cook at 15 lbs. for 15 minutes.(This is the best method.)Place dishes and Coliscan bottles in an oven-proof bag, seal it, and heat in an oven at 300? F for 45 minutes.Place dishes and Coliscan bottles in a large pan, cover with water and boil for 45 minutes.Place 5 mL (about 1 teaspoon) of straight bleach onto the surface of the medium of each plate. Allow to sit at least 5 minutes. Place in a water-tight bag and discard in trash.Carbon DioxideFill test tube (0608) to 20 mL line with sample water. NOTE: For best results test on freshly obtained sample, and avoid splashing or prolonged contact with air. Add 2 drops of *Phenolphthalein Indicator, 1% (2246). If solution remains colorless, proceed to Step 3. If solution turns red, no free carbon dioxide is present. Fill Direct Reading Titrator (0380) with *Carbon Dioxide Reagent B (4253DR). Insert Titrator into center hole of titration tube cap. While gently swirling the tube, add Carbon Dioxide Reagent B (4253DR), one drop at a time, until a faint pink color is produced and persists for 30 seconds. Read test result directly from the scale where the large ring on the Titrator meets the Titrator barrel. Record as ppm Carbon Dioxide.HardnessFill the test tube (0608) to the 12.9 mL line with the water sample. Add five drops of *Hardness Reagent #5 (4483) and mix. Add five drops of *Hardness Reagent #6 Solution (4485) and mix. Solution will turn red if hardness is present. If solution is blue, there is no measurable amount of hardness. Fill the Direct Reading Titrator (0382) with Hardness Reagent #7 (4487DR) in the manner described in the instruction manual. Insert the titrator in the center hole of the test tube cap. While gently swirling the tube, slowly press the plunger to titrate the sample until the red color changes to blue. Read the test result directly from the scale where the large ring on the Titrator meets the Titrator barrel. The result is expressed as Total Hardness in ppm CaCO3. EXAMPLE: Plunger tip is 3 minor divisions below line 80. Test result is 80 plus (3 divisions x 4) equals 92 ppm. If the plunger tip reaches the bottom line on the titrator scale (200 ppm) before the endpoint color change occurs, refill the titrator and continue the titration. When recording the test result, be sure to include the value of the original amount of reagent dispensed (200 ppm). Parts per million CaCO3 test results may be converted to grains per gallon (gpg) CaCO3 by means of the following formula: gpg CaCO3 = ppm CaCO3 x 0.058SilicaFill test tube (0106) to 5 mL line with sample water. Add 7 drops of *Silica Reagent #1 (4571). Cap and mix by inverting 4 times. Add 6 drops of *Silica Reagent #2 (4467). Cap and mix. Wait 5 minutes. Add 6 drops of *Silica Reagent #3 (4468). Cap and mix. Wait 2 minutes. Use pipet (0352) to add 2 drops of *Reducing Reagent (6405). Cap and mix. A BLUE color will develop in 10 seconds if silica is present. Insert the Silica Octa-Slide 2 Bar (4465-01) into the Octa-Slide 2 Viewer (1101). Insert test tube into the Octa-Slide 2 Viewer. Match sample color to a color standard. Record as ppm Silica.ConductivityIt is best to sample away from shore and below the water surface, if possible. In free-flowing streams, there will usually be good mixing of the water, so that samples taken near the current will be quite representative of the stream as a whole. If you are sampling an impounded stream or a lake, there will be very little mixing; therefore, it is important to sample away from shore and at different depths, if possible. Do not drop the Vernier Conductivity Probe so that the entire electrode is submerged. The electrode is not constructed to withstand higher pressures, so seepage into electronic components of the electrode will resultSet the range switch on the Vernier probe sensor. Thoroughly rinse the lower section of the probe using distilled or deionized water. Connect the sensor to the interface (LabQuest Mini, LabQuest 2, etc.). Start the appropriate data-collection software (Logger Pro, Logger Lite, LabQuest App) if not already running, and choose New from File menu. The software will identify the sensor and load a default data-collection setup. You are now ready to collect data.When you are finished making measurements, rinse the electrode with distilled water. Store dry.Macroinvertebrates Sampling: Choose sample siteCollect sample either by wading into water or netting from shore. Try to scoop as little sediment as possible. Push and pull the net through water and aquatic vegetation. Dip net into water-filled bucket of water gently to collect macroinvertebrates. Sort out macroinvertebrates and identify them using a key. Release macroinvertebrates once finished. Data Recording A. WATER CHEMISTRY MEASUREMENTSBunn’s CreekSeine River Red RiverAssiniboine RiverOak Hammock MarshTemperature (?C)Nitrate (ppm)Phosphate (ppm) Dissolved Oxygen (ppm)pHTurbidity (NTU or JTU)*be sure to check which units were used at which location Coliforms & E. coli countCarbon dioxide (ppm)Hardness (ppm CaCO3)Silica (ppm)Conductivity Pollution Tolerance Index (PTI): The Pollution Tolerance Index is based on the concept of indicator organisms and tolerance levels. Indicator organisms are those organisms that are sensitive to water quality changes and respond in predictable ways to changes in their environment. Therefore, their presence or absence indicates something about water quality. The PTI is calculated by multiplying the number of types of organisms in each tolerance level by the index value for that level (1 = pollution sensitive, 2 = moderately tolerant, 3 = fairly tolerant, 4 = very tolerant) and adding the resulting numbers. (note: PTI can use either a 3 or 4 point scale) The pollution tolerance taxa groups for calculating this index can be found at: or on Ms. McCrindle’s website. Water quality is then assessed according to the following scale: excellent 23 and above good 17-22 fair 11-16 poor 10 or less ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download