Question 7: Observe figure and answer the following questions.
i. What ecological term is used to describe the DDT accumulation at different trophic levels?
ii. List any one effect of DDT accumulation on birds
iii. Will DDT accumulation lead to eutrophication?
iv. Does it affect the BOD?
v. Name disease caused by accumulation of any heavy metal.
Answer:
- Biomagnification
- DDT in water adversely affects the use of water and leads to water pollution. When the large number of pesticides or mercury is added and the toxins concentration level increase at each trophic level in the food chain is known as biomagnification, which leads to the mortality of the fishes; and high concentration of DDT in birds affects calcium metabolism. Egg shells become thin and breaks down before their maturity.
- Yes, DDT accumulation leads to eutrophication. Eutrophication is a phenomenon where the water bodies contains high amount of nutrients like phosphates and nitrates. These nutrients promote the growth of algae and its decomposition causes high level of organic matter. It depletes the water of available oxygen, leads to the death of aquatic organisms.
- Yes, it will affect the BOD. BOD (Biochemical Oxygen Demand) is the measurement of quantity of oxygen that is used by the microorganisms and the aerobic decomposers are used during the breakdown of organic matter or the biodegradable waste. If we add DDT in water, water quality decreases and BOD level increases.
- Minamata disease: caused due to contamination of Mercury in water bodies.
Lead lapsy: caused due to contamination of Lead in water bodies.
Fluorosis; Knock- knee syndrome: caused due to contamination of fluorides in ground water.
Many other diseases caused by accumulation of any heavy metals occurred; like:
Methanoglobinaemia, Arsenocosis etc.
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