Sediment là gì

Point Source & Nonpoint Sources of Pollution

For the purposes of regulation, the United States Environmental Protection Agency identifies two broad categories of pollution: point-source pollution & nonpoint-source pollution.

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River Pollution

Waste filled water is dumped into a river, polluting it for the people and animals who use it as a source for eating và drinking. 

Photograph by Kaentian Street


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Almost everything humans vị, from growing food lớn manufacturing products lớn generating electrithành phố, has the potential khổng lồ release pollution inlớn the environment. Regulatory agencies charged with protecting the environment identify two main categories of pollution: point-source & nonpoint-source pollution.

Point-source pollution is easy to lớn identify. As the name suggests, it comes from a single place. Nonpoint-source pollution is harder to identify và harder lớn address. It is pollution that comes from many places, all at once.

The United States Environmental Protection Agency (EPA) defines point source pollution as any contaminant that enters the environment from an easily identified và confined place. Examples include smokestacks, discharge pipes, & drainage ditches.

Factories và power plants can be a source of point-source pollution, affecting both air and water. Smokestacks may spew carbon monoxide, heavy metal, sulfur dioxide, nitroren dioxide, or “particulate matter” (small particles) into the air. Oil refineries, paper mills, & auto plants that use water as part of their manufacturing processes can discharge effluent—wastewater containing harmful chemical pollutants—into rivers, lakes, or the ocean.

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Municipal wastewater treatment plants are another common source of point-source pollution. Effluent from a treatment plant can introduce nutrients & harmful microbes inkhổng lồ waterways. Nutrients can cause a rampant growth of algae in water.

Nonpoint-source pollution is the opposite of point-source pollution, with pollutants released in a wide area. As an example, picture a city street during a thunderstorm. As rainwater flows over asphalternative text, it washes away drops of oil that leaked from car engines, particles of tire rubber, dog waste, và trash. The runoff goes inkhổng lồ a storm sewer and ends up in a nearby river. Runoff is a major cause of nonpoint-source pollution. It is a big problem in cities because of all the hard surfaces, including streets and roofs. The amount of pollutants washed from a single city blochồng might be small, but when you add up the miles and miles of pavement in a big thành phố you get a big problem.

In rural areas, runoff can wash sediment from the roads in a logged-over forest tract. It can also carry acid from abandoned mines and flush pesticides & fertilizer from farm fields. All of this pollution is likely to wind up in streams, rivers, and lakes.

Airborne pollutants are major contributors khổng lồ acid rain. It forms in the atmosphere when sulfur dioxide and nitroren oxides combine with water. Because acid rain results from the long-range movement of those pollutants from many factories and power plants, it is considered nonpoint-source pollution.

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In the United States, the Clean Air Act and the Clean Water Act have helped khổng lồ limit both point-source và nonpoint-source pollution. Thanks lớn these two legislative initiatives, in effect for some 50 years now, America’s air & water are cleaner today than they were for most of the 20th century.


Chuyên mục: Kiến Thức