Atmospheric measurements of CF₄ and other fluorocarbons containing the CF₃ grouping

Abstract

Careful measurements by GC/MS techniques on atmospheric carbon tetrafluoride confirm that itsconcentration 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, CF3CI, CF3Br, and C2FsCI. The concentrations of the first pair are about 4 pptv, and the latter two are about 0.7 pptv and 4 pptv, respectively. The C:F6 is produced simultaneously with CF4 in the manufacture of aluminium. CF3C1, CF3Br, and CeFsCI 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 ½t al. (1980). power of the GC/MS combination to detect, identify, and strip chart recorder. quantify the concentration of low-level trace gases in the at-Because of the low boiling points of many of the commosphere. Information is also presented concerning the pos-pounds being measured and the likelihood of evaporation sible sources of these compounds.during the concentration procedure, the cryotrap efficiencies for CF4, C:F6, and CF3C1 were measured using standards. In

Atmospheric Lifetimes of Long-Lived Halogenated Species

“…The simplest molecule in this class, CF,, is also a by-product of aluminum production. Three such compounds, CF, (3-3, C2F6 (3,5), and SF6 (6), have been observed in the atmosphere. The observed vertical profiles of these molecules are consistent with atmospheric lifetimes of hundreds of years.…”

Long-term tropospheric trend of octafluorocyclobutane (c-C<sub>4</sub>F<sub>8</sub> or PFC-318)

“…The first atmospheric measurements were reported in the late 1970s (Rasmussen et al, 1979) and it has a current tropospheric abundance in the region of 75 ppt (Khalil et al, 2003;Worton et al, 2007;Mühle et al, 2010). Other identified PFCs include C 2 F 6 , first reported by Penkett et al (1981), C 3 F 8 (Culbertson et al, 2000) and c-C 4 F 8 Sturges et al, 2000). The present-day abundances of these compounds are much lower than CF 4 , being typically in the range of a few ppt or less (Khalil et al, 2003;Culbertson et al, 2004;Worton et al, 2007;Mühle et al, 2010;Saito et al, 2010).…”

Potential effects of halons on stratospheric O3based on the montréal protocol

“…Khalil and Rasmussen (1987); A s , Singh et al (1988), 44°N at 10km; A«, Rasmussen and Khalil (1984) for January to December in the Arctic. CBrF 3 measurements: • , , , Penkett et al (1981) at the surface; U F , Fabianetal. (1981), 44°N at 10km; M K , Khalil and Rasmussen (1987); E s , Singh et al (1988), 44°N at 10km.…”