Biological Magnification

The problem occurs when a pollutant, such as DDT or mercury, is present in the environment. Chemically, these pollutants resemble essential inorganic nutrients and are brought into the producer's body and stored "by mistake". The tendency for toxic substances/poisons to increase in concentration in the tissues of organisms at each higher feeding level in a food chain.

Biological Magnification Many toxic substances can’t be broken down and therefore are stored and accumulated in living tissues, especially fat. Many toxic chemicals do not cause a great deal of harm when in low amounts.

Biological Magnification Because they are non- biodegradable, they remain in the environment for long periods of time. As a result, the chances of being consumed by organisms and entering the food chain increases.

Biological Magnification Because toxins increase at every level of the food chain, organisms that are at the top levels of the food chain are most greatly affected. Therefore, organisms who are affected the most by biomagnification are therefore 2 nd and 3 rd level consumers (including humans).

Biological Magnification Examples. DDT – used in pesticides in the mid 50’s and 60’s Heavy Metals – lead; formally used in paints and metal processing, mercury; used in gold mining PCBs – Polychlorinated Biphenols; used in fire retardants, plastics.

Summary: In order for a pollutant to biomagnify, the following conditions must be met: 1.The pollutant must be long-lived. 2.The pollutant must be concentrated by the producers. 3.The pollutant must be fat-soluble.

Work Read pg in Text Do Q. #1-6, and choose one of 9, 10, or 11. Read pg. 20 in pink booklet. Do pg. 21