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EVIDENCE FOR ORGANOSULFATES IN SECONDARY ORGANIC AEROSOL
Citation:
SURRATT, J. D., J. H. KROLL, T. E. KLEINDIENST, E. O. EDNEY, M. CLAEYS, A. SOROOSHIAN, N. L. NG, J. H. OFFENBERG, M. LEWANDOWSKI, M. JAOUI, R. FLAGAN, AND J. SEINFELD. EVIDENCE FOR ORGANOSULFATES IN SECONDARY ORGANIC AEROSOL . ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 41(2):517-527, (2007).
Impact/Purpose:
The information provided under this task will be used to develop gas phase chemical mechanisms for a number of air toxic compounds that will be selected by OAQPS. The chemical mechanisms can be used by AMD to carry out calculations that OAQPS will use to evaluate strategies for reducing risk associated with exposure to airborne air toxic compounds The improved set of gas phase chemical mechanisms will be contained in a report that is expected to serve as a FY06 APM.
Description:
Recent work has shown that particle-phase reactions contribute to the formation of secondary organic aerosol (SOA), with enhancements of SOA yields in the presence of acidic seed aerosol. In this study, the chemical composition of SOA from the photooxidations of α-pinene and isoprene, in the presence or absence of sulfate seed aerosol, is investigated through a series of controlled chamber experiments in two separate laboratories. By using electrospray ionization - mass spectrometry, sulfate esters in SOA produced in laboratory photooxidation experiments are identified for the first time. Sulfate esters are found to account for a larger fraction of the SOA mass when the acidity of seed aerosol is increased, a result consistent with aerosol acidity increasing SOA formation. Many of the isoprene and α-pinene sulfate esters identified in these chamber experiments are also found in ambient aerosol collected at several locations in the southeastern U.S. It is likely that this pathway is important for other biogenic terpenes, and may be important in the formation of humic-like substances (HULIS) in ambient aerosol.