Secondary Organic Aerosol Formation in the Southeastern United States

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This project will investigate lightweight oxidation products from anthropogenic and biogenic volatile organic compounds (VOCs) as a source for secondary organic aerosol (SOA) in urban Atlanta, Georgia. The mechanism through which SOA may be formed involves partitioning of low carbon-number, water-soluble, secondary VOCs to the particle aqueous phase where they are heterogeneously oxidized to lower vapor pressure products. To investigate this process the Principal Investigator (PI) proposes to undertake online measurements of a suite of small organic acid and carbonyl compounds in the gas and aerosol phases, along with additional ancillary measurements. These experiments will be conducted over an extended period of time at a variety of sites to examine factors that influence the gas-particle partitioning and its linkage to hydrophilic/hydrophobic fractions and overall particle water-soluble organic carbon mass. The motivation for the project is the unexpectedly high SOA concentrations observed in urban atmospheres that cannot be explained by current SOA formation chemical mechanisms.