Atmospheric life times

Tropical upwelling is the main process through which halocarbons are carried up into the stratosphere. Once there, they are distributed polewards along sloped isentiopic surfaces, and subject to photolysis by UV radiation. As Chou [13] have pointed out, UV absorption cross-sections of halocarbons depend strongly on the number of chlorine atoms attached to a particular carbon atom. Hence, stability and thus atmospheric life times increase with increasing number of fluorine replacing chlorine atoms (see 4. and table 1). 

Atkinson, R. (1987a) Estimation of OH radical reaction rate constants and atmospheric life times for polychlorobiphenyls, dibenzo-/>-dioxins and dibenzofurans. Environ. Sci. Technol. 21, 305-307. 

Atkinson, R., Aschmann, S.M., Winner, A. M., Jr., Pitts, J.N. (1985) Atmosphere gas phase loss process of chlorobenzene, benzo-trifluoride, and 4-chlorobenzotrifluoride and generalization of predictive technique for atmospheric life times of aromatic compounds. Archiv. Environ. Contam. Toxicol. 14, 417-425. 

Ozone depleter Ozone depletion potential is the value relative to that of CFC-11. It represents the amount of ozone destroyed by the emission of gas over its entire atmospheric life-time. Photochemical ozone creation potential is a relative value to that of etiiene to form ozone in an urban environment. Numerous solvents belong to both groups. 

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