ELECTRON SCAVENGING OF STRATOSPHERIC CHLORINE TO REDUCE OZONE DEPLETION - WILL IT WORK

A recently proposed scheme for reducing ozone depletion by electron sc avenging of stratospheric chlorine may be much less efficient than ori ginally thought by its proponents. The rapid photodetachment of the ne gative Cl-ion by sunlight is the main problem with the scheme. Photode tachment would prevent chlorine-bearing negative ions from ever becomi ng the major ions, even when large numbers of electrons (of the order of 10(6) el- cm-3) were artificially injected into the atmosphere at a n altitude of 40 approximately 45 km. This conclusion is corroborated by the observed fact that chlorine bearing negative ions are not the m ajor anions at these altitudes under normal conditions. The possible e xistence of negative chlorine ion chemistry based ozone depletion cycl es is a potential hazard with this scavenging scheme. This hazard coul d make this scheme counterproductive if it is attempted in the altitud e region where atomic oxygen is an important constituent.