Halocarbons in the Atmosphere: Trends and Vertical Profiles

Abstract

Very stable halocarbons such as chlorofluorocarbons (CFCs) and carbon tetrachloride are responsible for both the stratospheric ozone depletion and the global warming as they accumulate in the atmosphere. Background atmospheric concentrations of CFCs and other halocarbons have been determined accurately and precisely at surface level both in the northern hemisphere (Hokkaido) and in the southern hemisphere (Antarctica). The atmospheric concentrations of CFC-11 and CFC-12 have been increasing by 4% a year since 1979; the CFC-113 concentration tends to increase much faster (10-20% a year). Vertical profiles of major CFCs upto the stratosphere as determined in balloon experiments (grab-sampling and cryogenic sampling) over Japan reflect their behaviors in the stratospheric UV photolysis. © 1991, The Chemical Society of Japan. All rights reserved.