Sunday, March 27, 2011

Water pollution


The great solvent power of water has been making the creation of absolutely pure water a theoretical rather then a practical goal. Even the highest-quality distilled water is having dissolved grass and to a slight degree solids. The problem, therefore, has one of determining what quality of water has been required to meet a given purpose and then finding practical means of achieving that quality. The term ‘water pollution’ is referred to the addition to water of an excess of material that is harmful to humans, animals, or desirable aquatic life, or otherwise causes significant departures from the normal activities of various living communities in or near bodies of water. In reality, the term water pollution refers to any type of aquatic contamination between two extremes:
1.      A highly enriched, over productive biotic community, such as a river or lake with nutrients from sewage or fertilizer. The expression ‘water pollution’ seems to be clear to all. Nevertheless, it is worth determining its real meaning as this has changed in the course of time. Felfoldy’s precise definition is in the following, ‘Water pollution is every impact which changes the quality of our surface and subsoil waters to such a degree that its suitability either for human consumption or for the support of man’s natural life processes will decrease or case.’
Water sources of the world: According to our present knowledge the total water resources of the world amount to 26.6 trillion tone. Approximately 94.7% of this huge volume of water can occur in the lithosphere, its major part being bound to minerals which constitute the rock bed. This is known as bound water. These waters have been forming a part of the structure of minerals and get released only at high temperature. The ocean and sea from the greatest coherent volume of water to be found on the surface of the earth. They have been covering 70.84% of the 510 million km of surface area of our planet.
Classification of water: Water can be classified according to several principles like organic matter content, temperature conditions, turbulence etc. Thienemann’s classification can be considered as:
1.  Ground waters  
2.  Springs 
3.  Running waters 
4.  Standing water  
5.  Waters of unusual temperature and chemical composition: thermal waters, snow and ice, sewage, brackish waters, highly-saline and natron lakes and other waters having peculiar characteristics.
On the basis of the use of water domestic, industrial and agricultural sewage can be diminished. These have been very different in their composition and even within a certain group great differences can be observed concerning their content. Organic matter utilizable by heterotrophic organisms from the first group of nutrients, whereas the inorganic nutrients utilized by autotrophic organisms belong to the other one.

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