Eutrophication is death and decay of water bodies due to excessive concentration of nutrients particularly nitrate and phosphate.
What are the sources of nitrate?
(A) Petrochemical Industries
(B) Surface run off from the fields draining into water bodies.
What are the sources of Phosphate?
Principally, the main source of phosphate is Sewerage draining into the water bodies.
What happens in eutrophication?
Once nutrients are excessively concentrated in the water bodies, rapid growth of algal will occur. This is called algal bloom. Due to algal bloom, a thick mat of algae is formed on the surface of water, as a result of which sunlight received by water bodies decline.
This causes darkness and decline in temperature within the water body. Since algae is present between atmosphere and water body, the concentration of oxygen in water body declines. Once algae is dead, it gets decomposed. In this process of decomposition, oxygen becomes too deficient in water bodies, as a result of which biological oxygen demand (BOD) is increased. This condition is called eutrophication.
Eutrophication of water bodies in India:
Excessive use of chemical fertilizers, sewage draining into water bodies have affected water bodies of India.Ponds, lakes(e.g Pushkar lake), rivers and coastal areas are facing problem of eutrophication. Major tourist attractions like Dal lake (Kashmir) , Pushkar lake (Rajasthan) , Chilka lake (Odisha), Yamuna river are facing eutrophication.
What are the ways to control eutrophication?
1) Treatment of sewage water before allowing it to enter water bodies.
2) Physical removal of algae.
3) Construction of embankments along water bodies to divert surface run off coming from the fields.
4) Desilting of water bodies to remove decomposed materials from the surface.