Aerosol formation from sulphur dioxide in the presence of ozone and olefinic hydrocarbons

Abstract

The gas phase oxidation of sulphur dioxide in the presence of ozone and olefinic hydrocarbons has been studied at p.p.m. concentrations. The rate of oxidation was determined by measurement of the sulphuric acid aerosol formed from radioactive ³⁵SO₂. Sulphur dioxide and ozone do not react at an appreciable rate at low concentration, but in the presence of olefins a rapid oxidation of sulphur dioxide occurs. The kinetics of the reaction are consistent with a mechanism in which sulphur dioxide is oxidized in a fast reaction with a short-lived intermediate produced in the initial reaction of ozone with the olefinic double bond. This oxidation process is of considerable significance in the atmospheric chemistry of sulphur dioxide.