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March 03, 2011
Pollutants (or materials) in the environment are broadly of two types- a. biodegradable ones and b. Non- biodegradable
ones. Biodegradables are subjected to microbial decomposition and thus with no or minimum persistence time in environment, and accordingly follow the regular cyclic material flow. While non-biodegradables are not decomposed by microbes. They have thus long
persistent in environment, and are introduced in the biotic organisms along with nutrients food-stuff. They are neither metabolized nor excreted, but retained in unaltered state in higher concentration in organisms of higher trophic levels in the food-chain
of an ecosystem. Thus they lead to irreversible disease and death of the organisms and misbalancing the ecosystem.
The process where the stable and persistent non-biodegradable pollutants (matters/ chemicals) are accumulated in tissues
of biological organisms in a concentration that is much higher than its environmental concentration, which usually causes irreversible disease and death of organisms, ultimately lead to ecological imbalance is known as biomagnification.
Causes- Usually stable and non-biodegradable pollutants are lipophilic in nature, means they have the attraction towards
lipid. For this lipophilic character, they are partitioned from surrounding water into the lipid or adipose tissues of organisms. Examples are DDT, PCBs (Poly Chlorinated Biphenyls), salts of heavy metals (mercury, lead, cadmium etc.) and so on.