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Types of Water Pollution. Sewage Disease-causing agents Sediment pollution Inorganic plant and algal nutrients Organic compounds Inorganic chemicals Thermal pollution. Types of Water Pollution. Water pollution
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Types of Water Pollution Sewage Disease-causing agents Sediment pollution Inorganic plant and algal nutrients Organic compounds Inorganic chemicals Thermal pollution
Types of Water Pollution • Water pollution • Any physical or chemical change in water that adversely affects the health of humans and other organisms • Varies in magnitude by location • Major water pollution issues globally • Lack of disease-free water
Sewage • The release of wastewater from drains or sewers (toilets, washing machines, showers,…), Includes human wastes, soaps, and detergents
Sewage Causes 2 serious environmental problems: • Enrichment • Fertilization of a body of water by high levels of plant and algal nutrients (nitrogen & phosphorus) • Increase in Biological Oxygen Demand (BOD) • Amount of oxygen needed by microorganisms to decompose biological wastes • As BOD increases Dissolve Oxygen (DO) decreases • Leads to eutrophication
Inorganic Plant and Algal Nutrients • Chemical fertilizers such as nitrogen and phosphorus that stimulate the growth of plants and algae • Harmful in large concentrations • Sources: • Human and animal wastes, plant residues, atmospheric deposition, and fertilizer runoff • Causes: • Enrichment, eutrophication, bad odors, and a high BOD
Water Pollution from Agriculture Agriculture is leading source of water pollution in US • nitrates and phosphates from animal wastes and plants residues • High BOD for decomposition • Almost all streams and rivers are polluted with agricultural pesticides
Eutrophication • Eutrophication: the natural nutrient enrichment of a shallow lake, estuary or slow moving stream, mostly from runoff of plant nutrients from the surrounding land. • Cultural or Artificial Eutrophication: human activities accelerate the input of plant nutrients (mostly nitrate- and phosphate- containing effluents) to a lake.
Eutrophic Lake • Slow-flowing stream, lake or estuary enriched by inorganic plant and algal nutrients such as phosphorus • Often due to fertilizer or sewagerunoff
Oligotrophic Lake Unenriched, clear water that supports small populations of aquatic organisms
Cause/Effect of Eutrophication • fertilizers, sewage runoff...get into water • enrichment occurs due to increase of nutrients, ex. nitrogen and phosphorous • effect – high photosynthetic productivity(huge increase in algae and plants) • algae and plants die and settle to bottom • aerobic bacteria decompose the plant matter and increase BOD (aka use up the oxygen) • aquatic life suffers
Cultural Eutrophication Because this gets into our water supply from runoff, etc., and is something that is not normally in the water, it is considered pollution. 85% of large lakes near major population centers in the U.S. have some degree of cultural eutrophication.
POLLUTION OF FRESHWATER STREAMS • Flowing streams can recover from a moderate level of degradable water pollutants if they are not overloaded and their flows are not reduced. • In a flowing stream, the breakdown of degradable wastes by bacteria depletes DO and creates and oxygen sag curve. • This reduces or eliminates populations of organisms with high oxygen requirements within the oxygen sag curve.
POLLUTION OF FRESHWATER STREAMS • Most developed countries have sharply reduced point-source pollution but toxic chemicals and pollution from nonpoint sources are still a problem. • Stream pollution from discharges of untreated sewage and industrial wastes is a major problem in developing countries.
Explain why untreated sewage may kill fish when it is added directly to a body of water. How do Midwestern farmers threaten the livelihood of fishermen in the Gulf of Mexico?