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 o o Water pollution Any physical or chemical change in water that adversely affects the health of humans and other organisms Varies in magnitude by location o o Major water pollution issues globally Lack of disease-free water

Sewage o o The release of wastewater from drains or sewers (toilets, washing machines, showers,…), Includes human wastes, soaps, and detergents

Sewage Causes 2 serious environmental problems: o o Enrichment Fertilization of a body of water by high levels of plant and algal nutrients ( nitrogen & phosphorus ) o o 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

Sewage

Inorganic Plant and Algal Nutrients o o Chemical fertilizers such as nitrogen and phosphorus that stimulate the growth of plants and algae Harmful in large concentrations o o Sources: Human and animal wastes, plant residues, atmospheric deposition, and fertilizer runoff o o Causes: Enrichment, eutrophication, bad odors, and a high BOD

Water Pollution from Agriculture o o nitrates and phosphates from animal wastes and plants residues o o High BOD for decomposition o o Almost all streams and rivers are polluted with agricultural pesticides Agriculture is leading source of water pollution in US

Water Pollution from Agriculture

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 o o Slow-flowing stream, lake or estuary enriched by inorganic plant and algal nutrients such as phosphorus o o Often due to fertilizer or sewage runoff

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.

Inorganic Plant and Algal Nutrient- The Dead Zone

o o Explain why untreated sewage may kill fish when it is added directly to a body of water. o o How do Midwestern farmers threaten the livelihood of fishermen in the Gulf of Mexico?