Chlorofluorocarbons pollution from

Progress has been made in some areas since 1970. Emissions of pollutants from point sources into air and water have decreased. Toxic releases are decreasing. Some Superfund sites have been cleaned up. Businesses would no longer think of dumping a barrel of waste solvent on the ground at the landfill site so that the barrel could be used again for the same purpose. Control of pollutants from nonpoint sources is still a problem. There is now more international cooperation and discussion of global problems, such as ozone depletion by chlorofluorocarbons and the effect of... 

Absorption of ultraviolet radiation by O3 causes it to decompose to O2. In the upper atmosphere, therefore, a steady-state concentration of ozone is achieved, a concentration ordinarily sufficient to provide significant ultraviolet protection of the Earth s surface. However, pollutants in the upper atmosphere such as nitrogen oxides (some of which occur in trace amounts naturally) from high-flying aircraft and chlorine atoms from photolytic decomposition of chlorofluorocarbons (from aerosols, refrigerants, and other sources) catalyze the decomposition of ozone. The overall processes governing the concentration of ozone in the atmosphere are extremely complex. The following reactions can be studied in the laboratory and are examples of the processes believed to be involved in the atmosphere ... 

FIGURE 4-1 Vertical structure of the atmosphere. Weather phenomena are confined almost entirely to the troposphere, as are most air pollutants, which are removed by various processes before they can mix into the stratosphere. Certain long-lived pollutants, however, such as the chlorofluorocarbons (CFCs), do mix into the stratosphere, and other pollutants can be injected physically to stratospheric altitudes by processes such as volcanic eruptions or nuclear explosions. Note that more than one term may refer to a given layer of the atmosphere (adapted from Introduction to Meteorology, by F. W. Cole. Copyright 1970, John Wiley Sons, Inc. Reprinted by permission of John Wiley Sons, Inc.). 

Catalysts in the Earth s atmosphere are causing troubles. They are causing the ozone layer to break down. Ozone protects the Earth from harmful ultraviolet rays from the Sun. Chlorine is a catalyst in the upper atmosphere. The chlorine comes from chlorofluorocarbons, or CFCs, released into the atmosphere. Chlorine allows ozone to break down into oxygen. The chlorine remains and keeps destroying ozone. This has caused a hole in the ozone layer. Governments around the world have banned the production of CFCs. This hole in the ozone now appears to be shrinking. We must continue to protect the ozone layer by reducing pollution around the world. Some scientists believe the ozone layer could return to normal levels by 2075. 

Direct electroreduction methods are typically used for dechlorination of chlorinated pollutants in waters. The easy removal of Cl from chlorinated organics allows conversion of chlorofluorocarbons (CFCs) into hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and even fluorocarbons (FCs). ECFCs are much less destructive to the atmospheric ozone than CFCs, but HFCs and FCs are harmless to atmospheric ozone, although they may contribute to the greenhouse effect. 

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