Atmospheric measurements of CF4 and other fluorocarbons containing the CF3 grouping

Careful measurements by GC/MS techniques on atmospheric carbon tetrafluoride confirm that its concentration in 1979 was constant at about 69.9 pptv (standard deviation is 7.2 pptv). It is almost certainly produced entirely by emissions from the aluminium industry. Other compounds in the atmosphere containing the CF3 group have been identified by GC/MS as C2F6, CF3Cl, CF3Br, and C2F5Cl. The concentrations of the first pair are about 4 pptv, and the latter two are about 0.7 pptv and 4 pptv, respectively. The C2F6 is produced simultaneously with CF4 in the manufacture of aluminium. CF3Cl, CF3Br, and C2F5Cl are probably produced by the chemical industry. The environmental importance of these compounds is discussed in the context of two papers on CF4 recently published by Cicerone (1979) and by Wang et al. (1980).