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प्रश्न
Explain sources and effects of water pollution.
उत्तर
Sources of water pollution:
1. Effluents released from industrial units such as inorganic and organic pollutants, oil,
grease, plastic, metals, acids, toxic chemicals, colour dyes etc.
2. Discharge of untreated or partly treated sewage of domestic and municipal waste,
leachates from solid disposal.
3. Fertilizers, pesticides, soil additives from agricultural activities.
4. Human activities such bathing, washing, other customs and traditions.
Effects:
Effect on humans: The consumption of polluted water can lead to various water borne
diseases like cholera, typhoid, infectious hepatitis, amoebic dysentery etc. Toxic
substances polluting the water have several effects on human health. It may damage
liver, kidneys, brain and lead various diseases of the central nervous system. Some
examples of diseases due to water pollution Minamata disease, Itai-Itai disease, blue
baby syndrome, etc.
Effect on plants: Polluted water may also contain high concentrations of heavy metals
which are toxic for plants and hamper their growth. The excess amount of nitrates
and phosphates (fertilizers) that are run off into the nearby water bodies lead to an
increase in growth of certain plants on the surface of the water bodies. As a result the
water becomes deficient of dissolved oxygen which causes the aquatic life to perish.
This phenomenon is known as eutrophication. Polluted water becomes turbid and
lowers the amount of light that reaches the submerged plants that leads to reduction
of photosynthesis.
Effect on animals: Drinking polluted water causes the toxins in the water to enter the
body of the organism, which may lead to serious health disorders and even death in
many animals. The presence of harmful chemicals and pollutants in water makes the
survival of aquatic organisms extremely difficult. Bio magnification is the cumulative
increase of a persistent chemical substance in the successive trophic levels in a food
chain. An example is the decrease in the population of ospreys that consumed fishes,
due to bio magnification effects of DDT (insecticide) washed off into the nearby water
bodies.
