Ozone layer chemical destruction

The other global environmental problem, stratospheric ozone depletion, was less controversial and more imminent. The U.S. Senate Committee Report supporting the Clean Air Act Amendments of 1990 states, Destruction of the ozone layer is caused primarily by the release into the atmosphere of chlorofluorocarbons (CFCs) and similar manufactured substances—persistent chemicals that rise into the stratosphere where they catalyze the destruction of stratospheric ozone. A decrease in stratospheric ozone will allow more ultraviolet (UV) radiation to reach Earth, resulting in increased rates of disease in humans, including increased incidence of skin cancer, cataracts, and, potentially, suppression of the immune system. Increased UV radiation has also been shown to damage crops and marine resources."... 

When CFCs slowly rise in the atmosphere and reach the ozone layer, they are broken down into component molecular compounds and atoms by the UV rays of the sun. Some of these chemicals then react with ozone to break it down, thus reducing the amount of O3. Further, some chlorine (also from the oceans) and some other elements combine with the O and to form other chemicals. This also contributes to the reduction of ozone faster than natural processes can reform it. Ozone is a renewable resource. The issue is this can a balance be obtained between the destruction of ozone in the atmosphere, by both natural and man-made causes, and its natural regeneration ... 

There are various approaches to parameterizing the process of formation and destruction of the ozone layer. The difficulty of deriving dynamic models of the ozone cycle in the atmosphere has to do with the participation in the cycle of more than 75 chemical reactions, a qualitative and quantitative description of which is impossible without deriving detailed models of the many minor gas components of the atmosphere. Nevertheless, there are empirical models of the ozone layer, which make it possible, under the present climatic situation, to obtain adequate spatial distributions of ozone. For instance, Bekoryukov and Fedorov (1987) derived a simple empirical model of total ozone content confirmed by observational data for the Southern Hemisphere ... 

Oxidizer Chemical substance that causes oxygen to combine with another chemical substance examples include oxygen and hydrogen peroxide Ozone depletion Destruction of the stratospheric ozone layer that protects the Earth from harmful effects of ultraviolet radiation. Depletion of ozone layer is due to the breakdown of certain chlorine- and/or bromine-containing compounds (chlorofluorocarbons or halons), which break down when they reach the stratosphere and then catalytically destroy ozone molecules Ozone layer Protective layer in the atmosphere, about 15 miles above the ground. The ozone layer absorbs some of the sun s ultraviolet rays, thereby reducing the amount of potentially harmful radiation that reaches the Earth s surface PAHs Polycyclic aromatic hydrocarbons... 

Rasmussen et al. 1983). 1,1,1 -Trichloroethane removed by rain water would be expected to re-volatilize rapidly to the atmosphere. Because of its long half-life of 4 years in the atmosphere (see Section 5.3.2.1), tropospheric 1,1,1-trichloroethane will be transported to the stratosphere, where it will participate in the destruction of the ozone layer. It will also undergo long-distance transport from its sources of emissions to other remote and rural sites. This is confirmed by the detection of this synthetic chemical in forest areas of Northern and Southern Europe and in remote sites (Ciccioli et al. 1993). 

Ozone (O3) exists in the atmosphere, 20-40 km above sea level. Ozone absorbs UV radiation which would otherwise harm living things. The effects of ozone loss could include increased human cataracts and skin cancer, reduction of plankton in ocean waters and destruction of plants, including crops. Ozone layer destruction in the Antarctic was reported in 1985 a major cause of this was believed to be the release of chlorofluorocarbon compounds, such as CCI2F2 (CFCs). These compounds are chemically unreactive, non-toxic and odourless, properties which at one time caused them to be used as solvents, aerosol propellants, refrigerant fluids and blowing agents for expanded plastic foams. They are so stable, however, that they persist in the atmosphere for years and eventually enter its upper layers, where they are broken down by the powerful UV radiation emitted by the sun. Their decomposition products can then destroy ozone ... 

The infamous smog of Los Angeles and Tokyo (and of many large cities) is caused mainly by the existence of a vast number of motor cars whose emissions are trapped in a relatively small area. The cars emit NO2 which (in the presence of sunlight and unburned petrol) produces ozone and other chemical irritants. The NO2 often gives the air a hazy brown coloration. Some cities give the predicted daily ozone levels with the daily weather forecast The ozone is purely destructive it cannot reach the ozone layer sufficiently fast to reduce ozone depletion. 

Paul Crutzen, Mario Molina, and Sherwood Rowland shared the 1995 Nobel Prize in Chemistry for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone. Born in Amsterdam, Mexico City and Delaware, Ohio, respectively, in 1974 these three scientists alerted the world to an impending environmental disaster, possible destruction of the protective ozone layer by manmade chemicals. And yet nothing in their early backgrounds would have predicted this. 

Scientists have also implicated some bromine-containing chemicals in the destruction of the ozone layer. The chief culprit has been CHjBr, methyl bromide, a commonly used agricultural fumigant. Here again, it is the relatively weak G—Br bond that is broken by UV radiation to produce Br atoms, which act in the same role as Cl atoms to destroy ozone. 

Packaging materials are all, to varying extents, damaging to the environment. For example, the manufacture of poly(styrene) (PS) products involves the use of a variety of hazardous chemicals and starting materials, such as benzene, a known mutagen and a probable carcinogen. Chlorofluorocarbons have also been used in the manufacture of blown or expanded PS products. Chlorofluorocarbons have been linked to the destruction of the ozone layer. 

After the hot tritium reaction studies, Rowland also shifted his interests to atmospheric chemical reactions. He pointed out the danger of the possible destruction of the ozone layer... 

Ozone is formed in the stratosphere by radiation from the sun and helps to shield life on Earth from some of the sun s potentially destructive ultraviolet radiation. In the early 1970s, scientists suspected that the ozone layer was being depleted. By the 1980s, it became clear that the ozone shield is indeed thinning in some places and at times even has a seasonal hole in it, notably over Antarctica. The exact causes and actual extent of the depletion are not yet fully known, but most scientists believe that various chemicals in the air are responsible. 

A major concern with chlorofluorocarbons is destruction of the ozone layer (mentioned in"Chemical Connections Freons Tn this chapter).The ozone-consuming reactions are thought to occur through a radical chain mechanism. The production of one radical species derived from a CFC can destroy a large number of ozone molecules before any termination steps occur. 

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