AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Secondary Aerosol Formation from Oxidation of Dimethyl Selenide
ROYA BAHREINI, Alexander Frie, Ying-Hsuan Lin, C.M. Sabbir Ahmed, University of California, Riverside
Abstract Number: 552 Working Group: Aerosol Chemistry
Abstract Methylation of selenium by microorganisms in soils, wetlands, lakes, or oceans and through plant metabolism results in atmospheric emissions of volatile selenium, predominantly in the form of dimethyl selenide (DMSe). Although gas phase oxidation kinetics of dimethyl selenide with major oxidants are known, the atmospheric fate of its oxidation products and the potential to form aerosol particles have not been investigated before. To increase understanding of DMSe’s atmospheric fate, we performed its photooxidation (in the presence of nitric oxide) and ozonolysis in an environmental chamber. DMSe-derived aerosol was formed under both conditions, but higher yields were obtained in the photooxidation experiment. Bulk composition measurements of the aerosol using a time-of-flight aerosol mass spectrometer revealed that ~50% of the secondary aerosol mass in both experiments was from selenium containing fragments in the form of SeOz+, SeCxHy+, and SeCxHyO+ (where x, y, and z are integers). Aerosol density and overall composition were similar in both experiments, suggesting similar types of oxidation products were involved in aerosol growth. Atmospheric implications of these observations will be discussed.