Write critical notes on the following:
(a) Eutrophication
(b) Biological magnification
(c ) Groundwater depletion and ways for its replenishment

Explanation

Eutrophication : Natural ageing of a lake by nutrient enrichment of its water is known as eutrophication. In a young lake, the water is cold and clear supporting little life. Gradually nutrients such as nitrates and phosphates are carried into the lake via streams, in course of time. This encourages the growth of aquatic algae and other plants. Consequently the animal life proliferates and organic matter gets deposited on the bottom of the lake. Over centuries, as silt and organic debris piles up the lake grows shallower and warmer. As a result, the aquatic organisms thriving in the cold environment are gradually replaced by warm water organisms. Marsh plants appear by taking root in the shallow regions of the lake. Eventually the lake gives way to large masses of floating plants (bog) and finally converted into land.