AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Chamber Simulation of Photochemistry of Mineral Dust Particles in the Presence of SO2
JIYEON PARK, Myoseon Jang, University of Florida
Abstract Number: 337 Working Group: Aerosol Chemistry
Abstract Mineral dust particles are one of the largest contributors to global aerosol mass loading, and yet the role of mineral dust particles in atmospheric photochemical process is not fully understood. In this study, heterogeneous photochemistry of Arizona test dust (size ranges: 0-3 µm) in the presence of SO2 were investigated with varying relative humidity (RH) and trace gas (e.g., NO2 and O3) concentrations using both a 2 m3 indoor Teflon film chamber with UV lamps, and dual 52 m3 outdoor chamber under natural sunlight. To evaluate the effect of surface functionalization of mineral dust particles (e.g., O-H stretching bands) on heterogeneous photochemistry, untreated and baked Arizona test dust were used. In addition, control experiments were conducted with various types of laboratory-generated particles such as SiO2, MgSO4, and (NH4)2SO4. Data represent that new particle formation was clearly observed for the Arizona test dust and SiO2 particles in the presence of SO2 under the natural sunlight with a significant increase of sulfate up to 10 µg/m3, whereas sulfate formation was negligible for inorganic salt aerosols (e.g., MgSO4 and (NH4)2SO4). Under weak or no UV light, little sulfate was observed for the Arizona test dust particles in the presence of SO2 at the low and high RH conditions. This suggests that SO2 is photochemically oxidized into sulfate ions via the heterogeneous chemistry of SO2 with dust surface-origin OH radicals, which are generated through electron-hole pairs on the surface of dust particles. The resulting chamber data are used to determine the reaction rate constant of SO2 in the presence of mineral dust particle. Further analyses for determining effects of natural dusts on the heterogeneous reaction in the presence of SO2 using various types of mineral dusts sampled from Gobi deserts, Mongolia are in progress, and will be presented.