Pollution — Science STD 8 — Question

The effluents and other substances released by man into the surrounding water bodies together can be called man-made reasons for water pollution.
1. Domestic sewage: The excreta, urine and other domestic-use water is added to the water bodies in many cities and villages. In big metro-cities, the sewage is partially treated but these management practices are not enough.

2. Industrial effluent: Different industries and factories release effluents which may contain toxic and harmful components, such as various pigments, bleaching chemicals, leather pieces, fibres, mercury, lead, etc.

3. Oil pollution: Oil spillages are seen in the seas due to leakage of crude oil. The crude oil is hazardous as it contains cancer causing hydrocarbons.

4. Fertilizers and pesticides: These compounds when used in farm, may get washed off to nearby water body. The chemical fertilizer containing N, P, K cause water pollution. Pesticides such as endrin, chlorine, carbonate containing pesticides, etc. are mixed with water. They cause contamination of the aquatic animals.

5. The wrong behaviour of human beings causes water pollution. The addition of wastes, defecation near coasts, washing clothes, decomposing hemp and flax in water, disposal of ashes, floral offerings to god, dumping ashes all such activities result into water pollution.

6. The warm water released into the water body through thermal power plants cause thermal pollution.