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List the 4 National Taps that work together to ensure a reliable and sustainable water supply to Singapore.
Find out the amount of water Singapore consumes in a year over the years.
|Year |Amount of water consumed in a year |
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NEWater is the high-grade water produced after treated used water has been further purified. List the 3-step process involved.
Step 1: ___________________________
Step 2: ___________________________
Step 3: ___________________________
Describe the 4 stages in a water cycle.
List 4 different ways to use water wisely at home.
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You will need to collect water samples to do the following:
|pH measurement (on-site) |
|Measurement of temperature (on-site) |
|Sedimentation observation (on-site) |
|Light permeability (on-site) |
|Amount of dissolved oxygen (on-site) |
|Land pollution observation (on-site) |
|Presence of bacteria or parasites (lab) |
STATION 1
What is pH?
It is a measure of the acidity or alkalinity of a substance.
- pH less than 7: acidic (eg. Lemon)
- pH more than 7: alkaline (eg. Detergent)
- pH equals 7: neutral (Pure water)
|Increasing acidity |
|pH 5 to 6 |growth of plankton and mosses |
|(mildly acidic) |populations of fish such as smallmouth bass disappear |
|Below pH 4.5 |bottom is covered with undecayed material |
| |mosses found near shore |
| |no fish can survive because aluminium ions causes excessive mucus in gills of fish, causing them to |
| |suffocate. |
| |also affects the reproduction of fish. |
|Increasing alkalinity |
|pH 8 to 9 |strips off slime coat of fish |
| |skin of fish ‘chaps’ |
|Above pH 9 |damage fish gills, eyes and skin |
| |cannot dispose wastes from body of fish |
| |death of fish populations |
Measuring pH
|Location A | |
|Location B | |
|Location C | |
|Average pH | |
STATION 2
How does temperature affect water organisms?
Thermal pollution from power plants, storm water run-off, and other sources can raise overall water temperature.
|Aquatic Plants |
|Growing season |Warmer water means longer growing season for plants |
| |Extremely cold water slows the growth of nuisance plants like weeds. |
|Algae growth |Algae are tiny free floating plants that increase in warmer water. |
|Bouyancy |increased temperature means increased photosynthesis |
| |these results in more buoyant plants (ability to float) |
|Depth |some plants cannot grow below certain depths even though there is enough light |
| |plant growth is ‘limited’ by temperature. |
|Aquatic animals |
|Amount of dissolved oxygen|warm water contains less dissolved oxygen than cool water |
|Growth rate and metabolism|as fish are cold blooded, they become less active in cool water. They eat less and grow less. |
|Respiration rate |animals are more active in warm water. |
| |They breathe faster and this might decrease the amount of dissolved oxygen. |
| |If there is not enough oxygen, many animals and plants will die. |
|Reproduction |Increases of decreases in water temperature can kill fish eggs |
| |Changes in temperature can cause adult fish to abandon their nests. |
|Distribution of animal |Some species prefer cooler temperatures while others prefer warmer temperatures. |
|life |Coldwater fish (less than 21 (C) |
| |Coolwater fish (22-23(C) |
| |Warmwater fish (25-28(C) |
Measuring temperature
|Location A |(C |
|Location B |(C |
|Location C |(C |
|Average temperature |(C |
STATION 3
What is sedimentation?
Sedimentation refers to the amount of suspended sediments or particles in water. More sedimentation could indicate more run-offs and pollution.
Measuring sedimentation (clear / murky / cloudy)
|Location A | |
|Location B | |
|Location C | |
|General observation | |
STATION 4[pic]
What is light permeability?
Light permeability refers to the amount of light that can pass through water.
It is affected by the amount of sedimentation in the water (see station 3).
Measuring light permeability (lux)
|Location A | lux |
|Location B | lux |
|Location C | lux |
|Average | lux |
STATION 5
What does dissolved oxygen tell us about water quality?
Dissolved oxygen is the most important test for water quality.
Oxygen concentration is affected by:
|Temperature |Colder water holds more dissolved oxygen |
|Rate of water flow |More movement means more dissolved oxygen |
|Time of day |Levels increase from morning to late afternoon due to photosynthesis |
| |Levels decrease throughout the evening. |
|Decomposition |Decomposition of plants and animals uses up oxygen |
|Runoffs |Runoffs due to soil erosion or pollution entering the water source will decrease dissolved oxygen. |
The amount of oxygen dissolved in the water will determine the amount of life in the water. The amount of
|Oxygen contents |Interpretation of Results |Possible inference |
|0.5 mg/l (ppm) |Dangerously low – insufficient oxygen for all fish|Serious pollution, water stagnation, decomposition due|
| | |to death of aquatic life. |
|2.0 mg/l (ppm) |Seriously low, only sufficient for robust or big |Some form of pollution and decomposition present |
| |fish | |
|4.0 mg/l (ppm) |Minimum level. Sufficient only for some kinds of |Depending on the species of fish and plants, some form|
| |fish |of life would be able to thrive. |
|6.0 mg/l (ppm) |Sufficient, plenty of oxygen for most kinds of |Most marine and aquatic life would be able to thrive. |
| |fish | |
|8.0 mg/l (ppm) |Good, plenty of oygen for all kinds of fish. | |
The oxygen content in Singapore’s tap water is about 4.0mg/l.
Measuring dissolved oxygen (mg/l)
|Location A |mg/l |
|Location B |mg/l |
|Location C |mg/l |
|Average |mg/l |
STATION 6
How does land pollution affect water?
Much of land pollution results from human waste from human activity.
Wind and rain causes pollutants on land to enter or seep into the water.
|Type of Litter |Mass (kg) |Can be decomposed? |
| | |Yes |No |
|Paper | | | |
|Metal | | | |
|Plastic | | | |
|Leaves | | | |
|Wood | | | |
|Total Mass | | | |
When something can be decomposed, it can be broken down into simpler substances by the action of decomposers such as bacteria.
Proportion of litter that can be decomposed
( (mass of decomposable litter ÷ total mass of litter) = ______ ÷ _______ = ___________
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Name: ____________________________________
Class: 5_______________________________
[pic]
Cannot be recycled
Can be recycled
Cannot be decomposed
Can be decomposed
Type of beach litter
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