Pollutants of Water and their Effects

Pollutants of Water and their Effects

Pollutants of water and their effects

Pollutants	Effects
Organic wastes: sewage, decaying plants, animal manures, wastes from food processing plants, oil refineries andleather paper and textile plants.	Increase BOD of water
Pathogens	Cause diseases in humans who drink the water
Inorganic chemicals and minerals	Increase the salinity and acidity of water and render it toxic.
Synthetic organic chemicals herbicides, pesticides, detergents, plastics, industrial wastes.	Cause birth defects, cancer, neurological damage and other illness.
Plant nutrients	Cause uncontrolled growth of aquatic plants (eutrophication) impart undesirable odour and taste to drinking water.
Sediments from land erosion	Cause silting of waterways and destruction of hydroelectric equipments near dams. Reduce light reaching plants in water and oxygen content of water.
Radioactive wastes	Cause cancer, birth defects, radiation sickness.
Heated water	Reduces oxygen solubility in water, alters habitats and kind of organisms present, encourages growth of aquatic life but can decrease the growth of desired fishes.

Industrial effluents Untreated industrial effluents can pollute water sources. In Japan, people were poisoned either directly or through eating fish contaminated by traces of mercury from a metallurgical plant. Even in many parts of India ground water remains polluted with toxic chemicals like arsenic which play havoc in the lives of the people living in that part of the country (West Bengal). Wastes from paper and pulp mills contain a heavy load of fibrous material that usually block pipes and sewers. Effluents from plastic factories contain a high content of phenols that give obnoxious taste to the water. Industrial wastes from metal finishing and electroplating units contain heavy metals and cyanides that add to water pollution.

Faecal pollution Human and animal excreta may enter into potable water sources either through sewage infiltration or due to lack of sanitation. Pathogenic microorganisms thus enter water sources and are responsible for major outbreaks within communities.

Temperature Water used for cooling atomic reactors and power stations are discharged into rivers and streams. It increases the temperature of water and reduces oxygen content.

Oils Both sea and river waters are polluted by crude oil due to accident, transport, etc. Seawater may also be polluted due to offshore oil production and oil refineries which discharge their wastes into marine system.

Harmful effects of oil
It causes fire in sea and river as a result of which aquatic plants and animals are completely destroyed.
It prevents oxygenation of water.

Oil deposits in animal systems like gills and scales of fish results in death of the animal.

It is estimated that presence of oil in water is a serious obstacle to the process of carbon assimilation in the phytoplankton.

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