Short article on water pollution
Contamination of water by sewage or fertilizer or by industrial effluents making it unfit for life of biotic communities is called water pollution. Natural water contains certain amount of dissolved salts and gases. If the amount of dissolved salts and other toxic materials increased by artificial addition making it unfit for drinking, pisiculture and agriculture purposes than, that water is said to be polluted.
Aquatic pollutants originate from many sources like (1) domestic sewages (2) chemicals like insecticides, herbicides, etc, (3) minerals and chemicals from industries (4) plant, nutrients and sediment from land erosions (5) heat from power plants (6) radioactive elements. Domestic sewages and fertilisers stimulate growth of microorganisms hence they are called excessive nutrients.
They are also called oxygen demanding waste since the stimulation of growth of microorganism results in the increase of biological oxygen demand. This reduces the amount of available O2 to the fishes and other aquatic organisms and result in their death.
Types of water pollution:
Water pollution is classified according to medium and also on the type of contamination. According to medium they are called as surface water pollution, lake pollution, river pollution etc. According to source or type of pollution they are referred to as, bacterial pollution, nutrient pollution, pesticidal pollution, thermal pollution, sewage pollution, industrial pollution etc.,
Sewage consists of biodegradable pollutants such as human waste matter, animal wastes, dissolved organic compounds and inorganic salts and various types.