CHClF₂ (F‐22) in the Earth's atmosphere

Abstract

Recent global measurements of CHClF2 (F‐22) are reported. Originally, GC/MS techniques were used to obtain these data. Since then, significant advances using an O2‐doped electron capture detector have been made in the analytical techniques, so that F‐22 can be measured by EC/GC methods at ambient concentrations. The atmospheric burden of F‐22 calculated from these measurements (average mixing ratio, mid‐1979, ∼45 pptv) is considerably greater than that expected from the estimates of direct industrial emissions (average mixing ratio, mid‐1979, ∼30 pptv). This difference is probably due to underestimates of F‐22 emissions.

Diode Laser Jet Spectra and Analysis of the ν3 and ν8 Fundamentals of CHF2Cl

“…More recently infrared spectra have been obtained from the ground (3), from balloons (4), and from a space shuttle (ATMOS/Spacelab3) (1). Through the analysis of these infrared spectra a steady increase of the CFC 22 concentration in the troposhere from 1980 up to now has been observed (1,2,5). Reference (1) reports an increase from 51 ± 8 pptv (1981) up to 102 ± 10 pptv (1988), corresponding to increase rates of 9.4 ± 1.3%/yr from 1981 to 1988 (1) (cf.…”

“…McLay and Mann (13) were among the first to determine a structure for CHF 2 Cl from microwave spectra. Later a more complete analysis of microwave data was performed by Cramb et al (14), yielding a reliable set of molecular ground state parameters, including quartic constants.…”

“…11.7%/yr from 1976 to 1981 (6)). It is well known that CHF 2 Cl contributes to ozone depletion and global warming (green house effect). The tropospheric lifetime, due to UV photolysis and oxidation by OH radicals (7), of CHF 2 Cl is about 10-30 years (1,2,(6)(7)(8); the most recent estimated lifetime is 15-20 years (9).…”

“…It is well known that CHF 2 Cl contributes to ozone depletion and global warming (green house effect). The tropospheric lifetime, due to UV photolysis and oxidation by OH radicals (7), of CHF 2 Cl is about 10-30 years (1,2,(6)(7)(8); the most recent estimated lifetime is 15-20 years (9). The analysis of infrared tropospheric and stratospheric spectra is hindered by the lack of detailed spectroscopic knowledge (absorption cross sections, quantum assignments, line broadening parameters) even for the strongest bands in the atmospheric window (8-13 µm tational (and vibrational) cooling can be obtained by expanding seeded mixtures of CFC's in a supersonic jet, thus simplifying the absorption spectra.…”

“…The atmospheric release rates grew from 53 × 10 9 g/yr (1975) to 95 · 10 9 g/yr in 1985 (1). The concentration of CHF 2 Cl in the atmosphere (troposphere and lower stratosphere) was measured initially by GC/MC techniques ( gas chromatography combined with mass spectrometry) on air samples (2). More recently infrared spectra have been obtained from the ground (3), from balloons (4), and from a space shuttle (ATMOS/Spacelab3) (1).…”