pollution - ENVST 110 Pollution Page 1 of 21 Pollution:...

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ENVST 110 Pollution Page 1 of 21 Pollution: (Most of the following is from Jay Davis.) Pollution is one of the primary ways in which humans have caused drastic modifications of wildlife habitat. Historically we have regarded the air, water, and soil that surround us as waste receptacles and have given little consideration to the ecological consequences of our actions. As a result, wildlife populations are confronted with a bewildering array of pollutants that we release into the environment either by intent or accident. In some cases wildlife populations have suffered severe losses or even faced extinction due to pollution. For example, the bald eagle, peregrine falcon, and brown pelican all nearly became extinct before scientists discovered that the synthetic chemical DDT was the cause of devastating reproductive failure in these species. Oil spills, such as the fouling of the coast of southern Alaska by the grounding of the Exxon Valdez, take an immediate toll on many species with the misfortune of living near such blunders. Toxic metals can kill adult members of wildlife populations and cause the production of deformed offspring, as seen at Kesterson Reservoir in the San Joaquin Valley. Acid rain has caused hundreds of fish populations to disappear from lakes in the northeastern U.S. and Scandinavia. In this chapter each of these notorious instances of the impacts of pollution on wildlife are described. The chapter also provides a general discussion of the origins and effects of synthetic chemicals, oil spills, toxic metals, and acid rain. What is pollution? Pollution can be defined as the human alteration of chemical or physical characteristics of the environment to a degree that is harmful to living organisms. Some forms of pollution exert a destructive influence on wildlife by killing or impairing the health of individuals. Synthetic chemicals, oil, toxic metals, and acid rain are included in this category of toxic pollutants. Other forms of pollution affect wildlife in a more indirect manner by altering or destroying wildlife habitat. Examples include the obliteration of canyons, marshes, and grasslands with solid waste landfills; the destruction of the ozone layer by chlorofluorocarbons, which may lead to widespread damage due to the effects of excessive ultraviolet radiation on wildlife and their food sources; and carbon dioxide accumulation in the atmosphere, which may lead to global changes in climate and the distribution of wildlife habitats. Although both of these categories of pollutants pose significant threats to wildlife, this chapter focuses on toxic pollutants because of their specific effects on wildlife. Different species vary in their sensitivity to toxic pollution. For example, populations of fish living in lakes in the northeastern U.S. have proven to be extremely intolerant of the increased acidity caused by acid rain. On the other hand, fish populations in naturally acidic Florida lakes thrive under conditions that would kill fish from northeastern lakes. Why are some fish populations sensitive to the effects of acidity while others are
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This note was uploaded on 10/26/2010 for the course ENVS 110 taught by Professor Green during the Fall '08 term at Santa Barbara City.

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pollution - ENVST 110 Pollution Page 1 of 21 Pollution:...

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