Thursday, October 4, 2007


Post by Voon Chen Li

Water Pollution is the contamination of any body of water or water supply, such as rivers and streams, lakes, underground water, or oceans by substances harmful to plants and animals. Water is necessary to life on earth. All organisms contain water and require that water to be relatively pure. Plants and animals cannot survive if their water contains toxic chemicals or harmful microorganisms. Water pollution can kill large numbers of fish, birds, and other animals, in some cases killing all members of a species in an affected area.

Major Types of Pollutants include but are not limited to chemical, biological, or physical materials that degrade water quality.

Hazardous wastes are chemical wastes that are either poisonous, capable of producing explosive or toxic gases, highly corrosive, or flammable. When improperly treated or stored, hazardous wastes can pollute water supplies. In 1969, in Cleveland, Ohio, the Cuyahoga River was so polluted with hazardous wastes that it actually caught fire. Hazardous wastes not properly disposed of or treated can get into the environment and reach toxic levels as organisms eat one another.

Oil and chemicals derived from oil are used for fuel, lubrication, plastics manufacturing, and many commercial and residential use. Petroleum products usually find their way into the water by means of accidental spills from ships, tanker trucks, leaking pipelines or leaking underground storage tanks. Most petroleum products are toxic to people, plants and animals, feathers and fur can be damaged by oil often causing death. Spilled oil may also contain other harmful substances, such as polychlorinated biphenyls (PCBs).

Herbicides and Pesticides are chemicals used to kill unwanted plants and animals. While these chemicals are typically used in agriculture or in the suburban back yard, they can end up in lakes, streams and ground water sources because of misuse or overuse. Carried by rainwater runoff, these chemicals can quickly cause eradication of aquatic plants and animals as well as illness in people.

Animals at the top of the food chain may be the first indicator that the water is polluted. Take for example a study done on DDT levels in Ospreys (a family of fish-eating birds). DDT levels were found to be 10 to 50 times higher than in the fish that they ate, 600 times the level in the plankton that the fish ate, and 10 million times higher than in the water.
Over 14 million Americans drink water contaminated with various pesticides, and the Environmental Protection Agency (EPA) estimates that 10% of wells contain pesticides in varying levels. Nitrates, a pollutant

LEARN MOREoften derived from fertilizer runoff, can cause methemoglobinemia in infants, a potentially lethal form of anemia that is also called blue baby syndrome.

Sediment or soil particles carried to a stream bed, lake, or ocean, can also be a pollutant when present in large enough amounts. Soil erosion is the typical reason for this and can be produced by many things. The removal of trees near waterways is a major contributor to erosion.
The Earth's topsoils can also find their way into streams by means of heavy rain runoff and floods in or near croplands, strip mines and roads. This high level of sediment and organic matter can damage a stream or lake by introducing too much nutrient matter which can lead to eutrophication (nutrient rich and oxygen poor).

Infectious Organisms The Centers for Disease Control and Prevention (CDC) have estimated that about 900,000 people get sick annually in the United States because of organisms in their drinking water, since about 900 of those people may die, the problem is serious. Some organisms occur in nature and are only considered pollutants when found in drinking water. One such parasite is Cryptosporidium parvum, which caused more than 400,000 illnesses and 100 deaths in Milwaukee in 1993 when it contaminated the drinking water supply.

No comments: