الأحد، 19 ديسمبر 2010

water pollution



http://en.wikipedia.org/wiki/Water_pollution



Water pollution is a major problem in the global context. It has been suggested that it is
the leading worldwide cause of deaths and diseases, and that it accounts for the deaths of more than 14,000 people daily.An estimated 700 million



Indians have no access to a proper toilet, and 1,000 Indian children die of diarrhea sickness every day.Some 90% of China's cities suffer from some degree of water pollution,and nearly 500 million people lack access to safe drinking water. In addition to the acute problems of water pollution in developing countries, industrialized countries continue to struggle with pollution problems as well. In the most recent national report on water quality in the United States, 45 percent of assessed stream miles, 47 percent of assessed lake acres, and 32 percent of assessed bay and estuarine square miles were classified as polluted.
Water is typically referred to as polluted when it is impaired by anthropogenic contaminants and either does not support a human use, like serving as drinking water, and/or undergoes a marked shift in its ability to support its constituent biotic communities, such as fish. Natural phenomena such as volcanoes, algae blooms, storms, and earthquakes also cause major changes in water quality and the ecological status of water.

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