AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Chemical Characterization of Water Soluble Organic Matter in Rural and Contrasting Urban Environments in the Southeastern United States
LU XU, Hongyu Guo, Rodney J. Weber, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 432 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Water-soluble organic matter (WSOM) is an important component of atmospheric particles. WSOM can alter the hygroscopicity of particles, affect particle water content, and further influence climate. However, the chemical composition of WSOM is not clear. In this study, we coupled a Particle-Into-Liquid-Sampler to a High-Resolution Time-of-Flight Mass Spectrometer (denoted as PILS-AMS) to continuously measure the chemical composition of WSOM in two contrasting environments, rural Centreville in Alabama (part of the Southeast Oxidant and Aerosol Study) and urban Atlanta in Georgia in summer, 2013. Our measurements showed that about 90% and 80% of OM is water-soluble in rural and urban sites, respectively. The fact that the majority of OM is water-soluble is consistent with our previous finding that OM in the southeast US in summer is mainly secondary. Positive Matrix Factorization (PMF) analysis was performed on both ambient total OM and WSOM for source apportionment. Based on comparison between ambient total OM and WSOM, we found that primary OM from vehicle emissions and cooking is not water-soluble. PMF factors representing secondary OM show different water solubility, which will be discussed in detail in the presentation. Studying the water solubility of OM subtypes largely improves our understanding of the sources of PMF factors.