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Types: Water Pollution
Overview
Water pollution is contamination of water by foreign matter that deteriorates the quality of the water. Water pollution covers pollutions in liquid forms like ocean pollution and river pollution. As the term applies, liquid pollution occurs in the oceans, lakes, streams, rivers, underground water and bays, in short liquid-containing areas. It involves the release of toxic substances, pathogenic germs, substances that require much oxygen to decompose, easy-soluble substances, radioactivity, etc. that become deposited upon the bottom and their accumulations will interfere with the condition of aquatic ecosystems. For example, the eutrophication: lack of oxygen in a water body caused by excessive algae growths because of enrichment of pollutants.
Water Cycle and Pollution
Water cycle is, simply saying, the circulation of water in earth. In fact, the water in the earth's biosphere is used and reused again and again. This is called water cycle or continuous movement of water between the earth and the atmosphere. It involves the following mechanisms:
Evaporation: changing of water from liquid to gas
Transpiration: Release of water vapor from plant leaves
Condensation: changing of vapor to liquid (cooled down)
Precipitation: Water that returns to the earth (water droplets in clouds become large enough and there comes the rain).
What's the relation of water cycle and pollution?
According to the water cycle, naturally, water around us will be absorbed to the land (soil) and rivers will stream from the upstream to the downstream and released to the sea. In normal situation organic pollutants are biodegraded by microbes and converted to a form that brings benefits to the aquatic life. And for the inorganic pollutants, in the same situation, don't bring to much hazards because they are widely dispersed and have almost no effect to the environment which they are released to.
In
a small scale, both inorganic and organic
pollutants safely decompose throughout the
stream, their concentration decrease in the sea,
and they don't harm the sea
ecosystem and its distribution. But in
an excessive scale, communities in
beach and estuary will be affected by
the pollutants, and can heavily harm
them.
Sources and Methods
We can classify major sources that lead to water pollution to the following categories:
Please click here to view a comprehensive table explaining the above major sources.
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©2001, Team C0111040, ThinkQuest.
