Polar ozone holes

The organic chemicals industry, although operating at a small fraction of the scale of the energy industry, nevertheless makes a substantial contribution to planetary problems, seen in the creation of polar ozone holes and in the damage inflicted,... 

Our review here will highlight the role of semiconductor-initiated photochemistry as an environmental remediation method for the treatment of organic chemicals. While the role of sunlight-induced photochemistry in creating environmental problems such as urban photochemical smog and the polar ozone holes has been well documented, the potential applications of photochemical methods in resolving environmental problems are less obvious. 

Gas-phase chemistry associated with the ClOj, and NO cycles is not capable of explaining the polar ozone hole phenomenon. Heterogeneous reactions occurring on PSCs play the pivotal role in polar ozone depletion (McElroy et al., 1986 Solomon et al., 1986 Molina, 1991). The ozone hole is sharply defined between about 12 and 24 km altitude. Polar stratospheric clouds occur in the altitude range 10 to 25 km. Ordinarily, liberation of active chlorine from the reservoir species HCl and CIONO2 is rather slow, but the PSCs promote... 

Earlier, in Chapter 6, we discussed the catalytic cycle involving chlorine free radicals generated by the effect of ultraviolet radiation on chlorofluorocarbons (CFCs). This cycle results in the phenomenon of ozone depletion and the consequent polar ozone holes . CFCs are not the only compounds that cause this depletion. Nitrogen oxides (NO, ) are also responsible. 

A29. Cmtzen, P.J., 1987 Recent Depletions of Ozone with Emphasis on the Polar Ozone Hole , in Kalla, 28 (Stockholm in Swedish). 

Interaction of acidic gases such as HCl with ice particles of PSCs is a key step in polar ozone hole chemistry [3]. The uptake efficiency of HCl, y, on ice is defined by the fractional collision frequency that leads to the reactant loss on ice surface. Until recently, a single laboratory measurement y 0.4 has been performed at HCl vapor... 

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