Tropospheric concentrations of methylchloroform, CH3CCl3, in January 1978 and estimates of the atmospheric residence times for hydrohalocarbons

  1. Yoshihiro Makide† and
  2. F. Sherwood Rowland‡
  1. *Department of Chemistry, University of California, Irvine, California 92717

Abstract

The ground level tropospheric concentrations of CH3CCl3 were measured from 55°N to 53°S during the time period around Jan. 1, 1978. The northern temperate zone concentration of CH3CCl3 averaged 94.6 ± 4.0 × 10-12 by volume. The southern temperate zone concentration averaged 65.2 ± 1.3 × 10-12, for a worldwide average of 80 × 10-12 by volume. The ratio of concentrations between the two zones is 1.45 ± 0.07. The observed CH3CCl3 concentrations correspond to 0.52 ± 0.05 times the atmospheric release to that date, corresponding to an atmospheric residence time of 6.9 ± 1.2 yr. The atmospheric residence times for 22 other hydrohalocarbon molecules were estimated in comparison to that of CH3CCl3 through the relative rates of reaction with OH radicals.

Footnotes

  • ↵ † Present address: Dept. of Chemistry, Univ. of Tokyo, Tokyo, Japan.

  • ↵ ‡ To whom reprint requests should be addressed.

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  1. PNAS 1981-10 vol. 78 no. 10 5933-5937
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