Comments on the Direct Aerosol Formation by Reaction of Ammonia and Sulfur Dioxide

Abstract

The atmospheric reaction between ammonia and sulfur dioxide is reconsidered in light of recent experimental studies. A mechanism is proposed that presumes the existence of the intermediate gas phase species NH3·SO2, prior to their nucleation and aerosol formation. Based on this mechanism and data obtained by other investigators, the vapor pressures of the solid compounds formed are estimated to be on the order of 10?4 to 10?7 torr. Thus, it is suggested that this process should not yet be dismissed as a possible route in the formation of atmospheric sulfate aerosols.