Ozone Depletion
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The Earth's upper atmosphere contains a layer of ozone. This layer acts to shield the surface from ultraviolet radiation. Ultraviolet radiation can have a variety of adverse effects on living things. Thus, the discovery of diminishing levels of springtime ozone levels high above Antarctica in 1985 caused widespread concern. The cause of this ozone depletion was found to be worldwide industrial production of chloroflourocarbons (CFCs). In response to this environmental threat, the world's governments gathered to discuss possible solutions. The result was an international treaty called the Montreal Protocol. This agreement calls for gradual reductions in global CFC production. It also provides for periodic reevaluation of the problem based on new scientific evidence. Considering recent studies which indicate that ozone depletion is an ongoing environmental problem, perhaps more stringent controls on CFC production are necessary. Given the extent of the damage, however, even an immediate CFC phaseout might not be sufficient to restore the planet's protective shield.The upper atmosphere's ozone layer extends from approximately 6 to 15 miles above the Earth's surface (Getis et al., 1988, p. 137). It forms a protective blanket which shields all life forms from overexposure to ultraviolet (UV) radiation. UV radiation comes from the sun. In large quantities, it has considerable potential for causing damage to living organisms. For example, excessive
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ganisms that attack the roots of fragile seedlings (Zurer, 1991, p. 24).
As these different chemicals break down, they may produce byproducts which cling to the ice crystals that form clouds in the Antarctic stratosphere (Cooper, 1992, p. 298). With the beginning of spring in the Southern Hemisphere, the return of sunlight acts as a catalyst; the eventual result being the destruction of atmospheric ozone (Chipperfield, 1993).
Typically, oxygen molecules in the stratosphere are transformed into ozone by solar UV radiation (Cooper, 1992, p. 292). The radiation splits the oxygen molecule, releasing highly reactive oxygen atoms which then bind to other oxygen molecules to form ozone molecules (Cooper, 1992, p. 292). This process, however, is interrupted by the presence of CFCs. UV radiation degrades CFC molecules to chemical byproducts such as chlorine and bromine (Fisher, 1990, p. 54). These elements attack the ozone molecules (Fisher, 1990, p. 54). For example, one chlorine atom might break off one of an ozone molecule's three oxygen atoms to form one chlorine monoxide molecule and one oxygen molecule (Fisher, 1990, p. 54). Then, when the chlorine monoxide molecule encounters a free oxygen atom, the compound
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Approximate Word count = 3313
Approximate Pages = 13 (250 words per page)
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