الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Water pollution is the presence of chemical, physical, or biological components or factors producing a condition of impairment of given water body with respect to some beneficial use. The level of contamination necessary to render a water body impaired is highly dependent on the type of water body, its location, and the types of beneficial uses it supports. A water source that is deemed unfit for drinking by humans may be suitable for other uses, such as habitat, irrigation, or recreation. Water pollution arises from certain natural events as well as anthropogenic sources of pollution, that is, pollution arising from human activities (1).The sources of pollution in general are divided into point sources and nonpoint sources. Point sources are localized identifiable sources of contaminants, such as power plants, refineries, mines, factories, wastewater treatment plants, etc. Nonpoint sources are those that are distributed over a wide geographic area, such as a watershed. Nonpoint sources can also include mobile sources such as cars, buses, and trains. Although each of these is a point source, they are moving and thus spread their cumulative impact over a large geographic area. A typical nonpoint source of pollution would be urban runoff, where the contaminant load may be the sum of thousands of small point sources within the watershed (1).