Water Pollution

• Any change in physical biological and chemical properties of water is known as water pollution.
• Water pollution can also be defined as the addition of unwanted particles or removal of important components from the water due to manual or natural processes.

Causes:

• Components that lead to water pollution are known as water pollutants. They arise from different sources.

Sewage:

• Sewage water contains waste organic matter arising from domestic set up, dairy farms, poultry farms, piggeries, slaughter houses etc. Mixing of sewage water with fresh water resource leads to its contamination. Also animal excreta discharged in fields or dumped in pits reaches water resource due to run off or leaching hence causing water pollution.

Industries:

• Many industries discharge the waste containing acids, alkalies, heavy metals etc directly into the water resources that adds to the water pollution.
• Discharge of hot water from industries leads to the change in the temperature of water thus disturbing aquatic life.

Agriculture:

• Pesticides and fertilizers used excessively in agricultural fields may be washed away by irrigation and rain and are added to the water resources.

Petroleum oil:

• Spillage or leaking of petroleum in water resources due to shipping, drilling or accidents is one of the serious causes for water pollution and has drastic effect on aquatic life.
• Other causes of it can be addition of synthetic soaps, detergents, chemicals, solid waste etc. all these together increases inorganic/ organic components in water resources leading to eutrophication, depletion in dissolved oxygen or change in the temperature hence having drastic effects on us.

Effects of water pollution:

Addition of undesirable substances:

• These substances could be the fertilizers, pesticides, poisonous mercury salts used by paper-industries or disease-causing organism like the bacteria which cause cholera.

Removal of desirable substances in water bodies:

• Dissolved oxygen is used by the animals and plants. Any change that reduces the amount of this oxygen would adversely affect the life of aquatic organisms.

Temperature change:

• Aquatic organisms need a certain range of temperature in the water-body for their survival.  Sudden marked change in this temperature due to the discharge of hot water into them affects their survival and breeding.
• The eggs and larvae of various animals are particularly susceptible to temperature changes.
• Sex of some species determined by the temperature to which their eggs are exposed. Thus water pollution can cause the misbalancing in the sex ratio.

Destruction of micro organisms/aquatic life:

• Contamination of water resource can inhibit the growth or kill some organisms. This will lead to the misbalancing of important natural processes like food chain, purification of water, cleansing system etc.

Shortage of clean and safe water for drinking and irrigation:

• Water pollution leads to the impure water which is unsafe for our life and crop production.

Means of spread of diseases:

• Contaminated water serves as the source for the growth of disease causing organisms and spread of water borne disease. It also encourages the growth of mosquitoes and other organisms that serve as the vectors for various diseases.

Eutrophication:

• Eutrophication is a process by which water pollution from sources like sewage effluent or leachate from fertilized fields causes a lake, pond, or fen to become over rich in organic and mineral nutrients, so that algae and cyanobacteria grow rapidly and deplete the oxygen supply.

Measures to prevent water pollution:

• Waste water should be treated prior to its discharge into the water source. That is it should be cleaned, toxic and solid material should be removed, chemical should be added so as to remove any harmful substances etc.
• The wastes and poisonous chemicals in the water released from mills, factories, chemical industries should be processed first for its purification and released thereafter.
• Hot water released from industries should cool down prior to its discharge.
• Bathing, washing and waste disposal in water reservoirs should be prohibited.
• Laws for preventing water pollution and punishing offenders should be made and implemented properly by the government.
• Example: Laws like the Water (Prevention and Control of Pollution) Act, 1974 lay down guidelines for control of water pollution.