Source Apportionment of Anthropogenic Secondary Organic Aerosol

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Secondary organic aerosols (SOA) are fine particles that arise from the oxidation of primary (volatile; VOC) organic compounds in the atmosphere. Secondary organic aerosols can have source contributions from both natural (e.g. from plants) and man-made (e.g. from unburnt hydrocarbons in automotive tailpipe emissions) sources. Source apportionment studies benefit society by improving our understanding of the sources of fine particulate matter, which has been shown to be correlated with excess morbidity, and is present in the air we breathe The science objectives of this research project will determine the anthropogenic SOA source characteristics, and their impact on fine particle concentrations (PM2.5; particulate matter less than 2.5microns) in urban areas relative to biogenic and other sources. A field-based approach will target ambient aerosol sampling at a number of urban locations: Houston, TX, Atlanta, GA, Milwaukee, WI. These are all sites where prior studies have established a mix of atmospheric loadings of anthropogenic volatile organic compounds (VOC) and biogenic compounds, allowing their respective contribution to SOA formation to be estimated. Anthropogenic activities that contribute to dangerous levels of criteria pollutants such as PM2.5 need to be identified and accurately quantified to source level before they can sensibly become targets of regulation or mitigation aimed at reducing ambient levels of fine particles. The approach used in this study centers on analysis of aromatic sulfonates, photoxidation products from aromatic VOCs, as chemical tracers of anthropogenic inputs into SOA.