AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
A Study of Secondary Organic Aerosol Formation Influenced by Mixed Anthropogenic and Biogenic Emissions in Atlanta Area by High Resolution Mass Spectrometer
LU XU, Hongyu Guo, Laura King, Vishal Verma, Rodney Weber, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 236 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Secondary organic aerosol (SOA) accounts for a major fraction of particulate mass and significantly affects the Earth’s climate and human health. However, SOA formation is controlled by complex processes which are not well understood. Specifically, to which extent human activities affect SOA formation and evolution is highly uncertain. The Atlanta area is an ideal location to investigate the effect of SOA production in mixed anthropogenic and biogenic emissions since this area is characterized by high emissions of both anthropogenic and biogenic sources. In this study, the formation of SOA is investigated by a comparison among Jefferson Street Site (Atlanta urban area), Yorkville Site (rural, 55km NW of Atlanta), and a roadside site (next to Interstate 75/85). Real-time particle instruments included an Aerodyne High-Resolution Time-of-Flight Mass Spectrometer (HR-ToF-AMS), a Multi-angle Absorption Photometer (MAAP), a Particle Into Liquid Sampler (PILS), and a Total Organic Carbon Analyzer (TOC). The HR-ToF-AMS was deployed to measure the size-revolved chemical composition of non-refractory submicron aerosol. Total mass concentrations of five major aerosol compositions, organics, nitrate, sulfate, ammonium, and chloride, at each sampling site are reported. In addition, elemental analyses are carried out to determine the oxygen/ carbon (O/C) and hydrogen/carbon (H/C) ratios of the bulk OA, which are indications of aerosol aging. Positive Matrix Factorization (PMF) is conducted on high mass-resolution (HR) organic aerosol (OA) spectra to deconvolve OA into different components. Hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA), which are surrogates of primary and secondary OA respectively, are found at all sites. Besides, isoprene-derived SOA is only detected in Yorkville during summer. The effect of anthropogenic emissions on SOA formation would be discussed based on the measurement results obtained at the three different sampling sites at different times.