THE EFFECT OF GAS-PHASE CHEMISTRY ON AQUEOUS-PHASE SULFUR-DIOXIDE OXIDATION RATES

The rates and mechanisms of both gas and liquid phase reactions for th e oxidation of sulfur dioxide play an important role in the production of atmospheric acids and aerosol particles. Rhode et al. (1981) concl uded that sulfate production rates were highly non-linear functions of sulfur dioxide emission rates. Their modelling study used an HO(x) te rmination mechanism for the HO-SO2 reaction in the gas-phase. Stockwel l and Calvert (1983) determined that one of the products of the overal l reaction of HO with sulfur dioxide was an HO2 radical. The National Research Council (1983) using a version of the Rhode et al. (1981) mod el modified to include HO2 production from the HO-SO2 reaction conclud ed that sulfate production becomes much more linear with respect to re ductions in sulfur dioxide emissions. However, the cause of this incre ased linearity was not explained by the National Research Council repo rt. It is demonstrated that the increased linearity is due to the coup ling of gas-phase and aqueous-phase chemistry. The gas-phase sulfur di oxide oxidation mechanism has a very significant effect on hydrogen pe rodide production rates.