Thursday, May 5, 2011

What is Bioaccumulation?
Simply Stated -

All living organisms are connected to each other through a food chain. It takes more organisms in the beginning of a food chain to support a smaller number of organisms at the end of the chain. Where bioaccumulation refers to how pollutants enter a food chain; biomagnification refers to the tendency of pollutants to concentrate as they move from one trophic level to the next, up the “food chain.”

Bioaccumulation refers to how pollutants enter a food chain
Biomagnification refers to the tendency of pollutants to concentrate

Biomagnification is illustrated by a study of DDT which showed that where soil levels were 10 parts per million (ppm), DDT reached a concentration of 141 ppm in earthworms and 444 ppm in robins. DDT which has a half-life of 15 years, Strontium 90 which has been shown in EPA testing results in the United States has a half-life of 28.9 years, Cesium 137 has also been found which has a half life of 30 years. Through biomagnification, the concentration of a chemical in the animal at the top of the food chain may be high enough to cause death or adverse effects on behavior, reproduction, or disease resistance and thus endanger that species, even when levels in the water, air, or soil are low.

We must be concerned about these phenomena because together they mean that even small concentrations of toxic substances in the environment can find their way into organisms in high enough dosages to cause problems. If a chemical is short-lived, it generally will be broken down before it can become dangerous. However, even if short-lived chemicals are exposed to the environment for long periods of time in heavy doses, they too can become dangerous. Bioaccumulation is affected by the length of time between uptake and elimination of chemicals. If the environmental concentration of the chemical increases, the amount inside the organism will increase until it reaches a new equilibrium. Exposure to large amounts of a chemical for a long period of time, however, may overwhelm the equilibrium (ie, overflowing a bathtub) potentially causing harmful effects.

The easiest way to prevent biomagnification is to lower/remove the pollutants from the environment, or remove those effected from the polluted area.

How do you prevent Biomagnification if you cannot control the length of exposure, or the amount of radiation introduced into the environment?

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