Water Quality
How do Scientists measure water quality?
-Water samples, aerial photography, and aquatic life forms -The health of a water body can be determined by analyzing physical, chemical and biological factors What chemical factors are used to measure water quality? -Dissolved oxygen (DO) -How much oxygen is available for organisms to breathe -What photosynthetic organisms are making/using oxygen -pH -Measure of chemicals dissolved in water -Too high or low can be deadly -Nutrients -NPK -Too many can stimulate algal growthàeutrophication -Toxins -Metals, pesticides, oils, etc |
What physical factors are used to measure water quality?
-Temperature -Dictates what life forms can survive -Correlated to the amount of direct sunlight -Warmer water contains less DO than cold water -Amount and speed of water -Some water is slow moving or even stagnant, where as obstructions or curved paths can create rapids -Substrate on bottom -Large sediments stir up more water, increasing DO -Turbidity (Clarity) - How much solid is being carried in the bedload What biological factors are used to measure water quality? -Pathogens -Viruses and bacteria (fecal coliforms), mostly from failing septic systems, untreated human waste, and animal waste -Bioindicators -Living things that provide information about water quality -Fish, plants, and macroinvertebrates (snails, worms, larvae) -Only species most tolerant will be found in heavily polluted waters |
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Dams and Diversion
What are the pros and cons to generating electricity from hydropower?
PROS -Dams are relatively inexpensive to operate. -Yet, they are very expensive to build. - Dams generate clean power -Hydropower is renewable and doesn’t emit greenhouse gases or other air pollutants* -Dams improve quality of life -prevent flooding*, create jobs, and provide cheap electricity, irrigation, and drinking water CONS -Dams alter river habitats in many ways upstream: flooding downstream: not enough water -Natural cycles are disrupted - floodplains don’t receive nutrients from sediments because they get trapped behind dams -Temperature of the water is changed à aquatic populations go extinct -Dams prevent anadromous fish from laying eggs Modern Trends -In the US, the era of large dam construction is probably over. –Not so in developing countries (Brazil, China, India). -Micro-hydropower :electricity produced in a small stream without having to build a big dam |
What are the Pros and cons of Water Division?
-Water diversion projects bring water to areas that need it -People have long diverted water to farm fields, homes, and cities The Aral Sea -Once the fourth-largest lake on Earth –It has lost more than 80% of its volume in just 45 years –The two rivers leading into the Aral Sea were diverted to irrigate cotton fields -Consequences of a shrinking sea –60,000 fishing jobs are gone –Pesticide-laden dust from the lake bed is blown into the air –The cotton cannot bring back the region’s economy Will we see a Future Water Wars? -Freshwater depletion leads to shortages, which can lead to conflict –261 major rivers cross national borders –Water is a key element in hostilities among Israel, Palestinians, and neighboring countries -Many nations have cooperated with neighbors to resolve disputes |