Pollution Essays -- essays research papers

Pollution, contamination of Earth's environment with materials that interfere with human health, the quality of life, or the natural functioning of ecosystems (living organisms and their physical surroundings). Although some environmental pollution is a result of natural causes such as volcanic eruptions, most is caused by human activities. There are two main categories of polluting materials, or pollutants. Advertisement Biodegradable pollutants are materials, such as sewage, that rapidly decompose by natural processes. These pollutants become a problem when added to the environment faster than they can decompose (see Sewage Disposal). Nondegradable pollutants are materials that either do not decompose or decompose slowly in the natural environment. Once contamination occurs, it is difficult or impossible to remove these pollutants from the environment. Nondegradable compounds such as dichlorodiphenyltrichloroethane (DDT), dioxins, polychlorinated biphenyls (PCBs), and radioactive materials can reach dangerous levels of accumulation as they are passed up the food chain into the bodies of progressively larger animals. For example, molecules of toxic compounds may collect on the surface of aquatic plants without doing much damage to the plants. A small fish that grazes on these plants accumulates a high concentration of the toxin. Larger fish or other carnivores that eat the small fish will accumulate even greater, and possibly life-threatening, concentrations of the compound. This process is known as bioaccumulation. II. Impacts of PollutionPrint section Because humans are at the top of the food chain, they are particularly vulnerable to the effects of nondegradable pollutants. This was clearly illustrated in the 1950s and 1960s when residents living near Minamata Bay, Japan, developed nervous disorders, tremors, and paralysis in a mysterious epidemic. More than 400 people died before authorities discovered that a local industry had released mercury into Minamata Bay. This highly toxic element accumulated in the bodies of local fish and eventually in the bodies of people who consumed the fish. More recently research has revealed that many chemical pollutants, such as DDT and PCBs, mimic sex hormones and interfere with the human body's reproductive and developmental functions. These substances are known as endocrine disrupters. See Occupationa... ...es of excessive noise. Page 1 of 2 See an outline for this article. How to cite this article  © 1993-2001 Microsoft Corporation. All Rights Reserved. Advertisement Related Articles Air Pollution bioindicators of environmental damage More... Books Encarta recommends Search for books about Pollution at BarnesandNoble.com Periodicals Search for periodical articles about Pollution in Electric Library. Free registration required Encarta Training Center Search for courses and materials on Pollution Internet Search from MSN Search News from MSNBC Related Web Sites EPA: US Environmental Protection Agency Noise Pollution Clearinghouse More Details Also on Encarta 10 words you should know Qwest: managed solutions Also on MSN MSN Pets: facts about furry friends Real estate tips from HomeAdvisor Our Partners The Princeton Review Studentloan.com Encarta Reference Library Learn about our award-winning CD and DVD products Please rate Encarta's 1 2 3 4 5 -select a reason- Exactly what I needed Was too technical Didn't provide enough detail Was out of date article on this topic. Poor Excellent Main reason for your rating