SO2 oxidation via the hydroxyl radical: Atmospheric fate of HSOx radicals

Reported in this study are the results from a gas kinetics — aerosol laboratory study involving the OH induced oxidation of SO2. At tropospheric and lower stratospheric pressures, reaction (1) is neither a third order process nor is it a simple bimolecular reaction. The effective bimolecular k value at one atmosphere (N2) pressure has been estimated by these authors to be 9 × 10−13cm³/molec/s. Based on estimated k values and concentrations for several trace gases, it is suggested here that the resulting HSO3 radical from reaction (1) under atmospheric conditions would react predominantly with O2 in both the lower stratosphere and the troposphere. It is further suggested that the product HSO5 radical would undergo hydration in both atmospheric regions.