::The Crying Earth::

5.1.2 Movement Distribution and Fate of Toxins

Toxic chemicals can move through the food chain from one trophic level to the next. This movement of toxins can lead to bioaccumulation and biomagnification of toxic chemicals in different organisms at each trophic level of the food chain.

• Bioaccumulation- it is the selective absorption and storage of a great variety of molecules. Toxins that are rather dilute in the environment can reach dangerous levels inside cells and tissues through bioaccumulation.

• Biomagnification - effects of toxins are magnified (increase) in the environment through food chains. It occurs when the toxic burden of a large number of organism at a lower trophic level is accumulated and concentrated by a predator in a higher trophic level. The small fish and zooplankton eat a vast quantities of phytoplankton. In doing so, any toxic chemicals accumulated by the phytoplankton are further concentrated in the bodies of the animals that eat them. This is repeated at each step in the food chain. This process of increasing concentration through the food chain is known as biomagnification. The top predators at the end of a long food chain, such as lake trout, large salmon and fish-eating gulls, may accumulate concentrations of a toxic chemical high enough to cause serious deformities or death even though the concentration of the chemical in the open water is extremely low. The concentration of some chemicals in the fatty tissue of top predators can be millions of times higher than the concentration in the open water