SO2 OXIDATION ON SALT PARTICLES - PROCESSES OF HETEROGENEOUS SULFATE FORMATION IN MARINE ATMOSPHERE

In aerosol systems the various chemical reactions leading to atmospheric trace gas removal are connected partially with each other but are also partially combined with gas phase reactions. Additionally these chemical conversions are superimposed by mixing and rarefactive processes. The importance of individual reaction pathways, i. e. the contribution of the heterogeneous SO2 oxidation to atmospheric sulfate formation, can therefore only be studied with the aid of controlled laboratory experiments. The investigations carried out on the sulfate formation in sea salt and in NaCl aerosols represent a contribution to clarify the significance of the heterogeneous SO2 oxidation in a marine atmosphere. The oxidative conversion of SO2 in sea salt aerosols depends on reaction parameters such as particle concentration, relative humidity, SO2 gas concentration and the presence of other trace gases. For this gas removal process reaction rates were obtained which can exceed the reaction rates of the homogeneous gas phase oxidation as well as those of the oxidation in cloud or fog droplets.