This project examines, through field observations, the hypothesis that sea-salt aerosol has alkalinity amounts enhanced over that in sea water, which then leads to increased importance of processes that are more important at higher pH (lower acidity), such as oxidation of sulfur dioxide by ozone. These processes compete with the aqueous phase oxidation of sulfur dioxide by hydrogen peroxide, and the gas phase oxidation by hydroxyl radicals. The investigations will be accomplished by making size resolved measurements of aerosol ionic composition under a variety of conditions of biological primary productivity, cloudiness, and season. Composition measurements as a function of aerosol size are important because the alkalinity enhancements appear to be more significant for larger sizes. These data will be used to derive estimates of the contribution of this mechanism to the global sulfur cycle.
This research will help define mechanisms that can be incorporated into chemical transport models that should lead to improved simulation of sulfur transformations in the marine boundary layer. Students will be supported and involved in this project.
