Atmospheric Concentrations of Halocarbons in Japan in 1979–1986

Abstract

Abstract The average atmospheric concentrations of halocarbons in the mid-latitude Northern Hemisphere have been measured accurately for 7 years from 1979 to 1986. Atmospheric samples were collected in summer and winter in Hokkaido (40–45°N), and the halocarbons at 10–400 pptv (pptv=10−12 v/v) concentrations were determined with 0.5% precision. The concentrations of halocarbons with long lifetimes have been increasing steadily (CCl2F2: 18 pptv/year, CCl3F: 8–9 pptv/year, CH3CCl3: 4 pptv/year, CCl4: 2 pptv/year); those of shortlived halocarbons (CHCl=CCl2 and CCl2=CCl2) are low (<25 pptv) and show only seasonal variations.