Earth ozone depletion cycles

Effect of Nitric Oxide on Ozone Depletion. Nitrous oxide is injected into the atmosphere from natural sources on earth about 10% is converted to nitric oxide (N20 + 0( D) — 2 NO), which in turn can catalyze the destmction of ozone (11,32,75). The two main cycles are 1 and 2. Rate constant data are given in Reference 11. 

Table V. Cycles for Ozone Depletion in Earth s Atmosphere...

One example of a catalytic cycle that has had serious environmental consequences is the role that chlorofluorocarbons (CFCs) play in the phenomenon of ozone depletion in the upper atmosphere, particularly over the Earth s poles. Concern grew following the detection of the Antarctic ozone hole and the identification of the chlorofluorocarbons used in aerosols, refrigerators and air-conditioning plants as mediators of this depletion. 

In the stratosphere, the region of the atmosphere from 10 up to 50 km, ozone is synthesized from dioxygen in a complex cycle of reactions. Thanks to its strong absorption of ultraviolet radiation in the range between 232 and 290 nm, ozone provides a protective shield for the plant and animal life on the earth s surface. Because no other atmospheric species can absorb the intense radiation in this range, the ozone layer is absolutely critical to the earth s inhabitants and has been the focus of numerous investigations. A major concern is the possible depletion of the ozone layer by nitrogen oxides from automobile exhausts and by Freons from aerosal sprays. 

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