pollution, contamination of the earth's environment with materials that interfere with human health, the quality of life, or the natural functioning of ecosystems(living organism and their physical surroundings). Although some environment pollution is a result of natural causes like volcanic eruption, most is caused by human activities.There are two main categories of polluting materials, or pollutants. Biodegradable pollutants are materials, such as sewage, that rapidly decompose by natural processes. These pollutants become a problem when added to the environment. Once contamination occurs, it is difficult or impossible to remove these pollutants from the environment.Impacts of pollutionBecause 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 1960s and 1970s when residents living near Minimata Bay, Japan, developed nervous disorders, tremors, and paralysis in a mysterious epidemic.Over 400 people died before authorities discovered that a local industry had released mercury into Minimata Bay. This highly toxic element accumulated in the bodies of local fish and eventually in the bodies of people who consumed the fish.Pollution also has a dramatic effect on natural resources. Ecosystems such as forests, wetlands, coral reefs and rivers perform many important services for the earth's environment. They enhance water and air quality. provide habitat for plants and animals, and provide food and medicines. Any or all of these ecosystem functions may be impaired or destroyed by pollution. Moreover, because of the complex relationships among the many types of organisms and ecosystems, environmental contamination may have far-reaching consequences that are not immediately obvious or that are difficult to predict. For instance, scientists can only speculate on some of the potential impacts of the depletion of the ozone layer, the protective layer in the atmosphere that shields the earth from the sun's harmful ultraviolet rays.Another major effect of pollution is the tremendous cost of pollution cleanup and prevention. The global effort to control emissions of carbon dioxide. a gas produced from the combustion of fossil fuels such as coal or oil, or of other organic materials like wood, is one such example. The cost of maintaining annual national carbon dioxide emissions at 1990 levels is estimated to be 2 percent of the gross domestic product for developed countries.
In addition to its effects on the economy, health, and natural resources, pollution has social implications. Research has shown that low-income populations and minorities do not receive the same protection from environmental contamination as do higher-income communities. Toxic waste incinerators, chemical plants, and solid waste dumps are often located in low-income communities because of a lack of organized, informed community involvement in municipal decision-making processes.
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