AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
BVOC Oxidation Products Measured by SV-TAG Reveal Differences in Chemistry and Partitioning between Natural and Polluted Environments Forming Secondary Organic Aerosol (SOA)
ALLEN H. GOLDSTEIN, Gabriel Isaacman, Lindsay Yee, Nathan Kreisberg, Suzane Simoes de Sa, Scot Martin, Lizabeth Alexander, Brett Palm, Weiwei Hu, Pedro Campuzano-Jost, Douglas Day, Jose-Luis Jimenez, Thien Khoi Nguyen, Annmarie Carlton, Juarez Viegas, Antonio O. Manzi, Rodrigo A. F. Souza, Maria Oliveira, Paulo Artaxo, Joel Brito, Eric Edgerton, Karsten Baumann, Susanne Hering, University of California, Berkeley
Abstract Number: 501 Working Group: Air Quality and Climate in the Southeast US: Insights from Recent Measurement Campaigns
Abstract Anthropogenic pollutants affect biogenic SOA formation, but the impacts and details of this interaction are still poorly understood. Though laboratory studies have characterized oxidation chemistry of isoprene and monoterpenes, few time-resolved atmospheric measurements of organic tracers are available to constrain the relative importance of chemical pathways. We present ambient hourly measurements of oxidation products of biogenic emissions in two locations: the Southeastern U.S. (SOAS 2013) and Amazonia, Brazil (GoAmazon 2014). In both of these measurement locations, high levels of biogenic emissions interact with plumes from nearby cities, enabling the study of anthropogenic-biogenic interactions in aerosol formation. A Semi-Volatile Thermal desorption Aerosol Gas chromatograph (SV-TAG) was modified to include simultaneous collection of particle-phase and total gas- and particle-phase compounds, and derivatization of hydroxyl groups prior to GC analysis. Using SV-TAG, concentrations and gas-particle partitioning of BVOC oxidation products were measured, providing ratios of tracers for different chemical pathways (i.e. with and without NOx influence) and compared to traditional partitioning models. Generally, traditionally-used tracers are found to exist in the particle-phase more than that predicted by equilibrium partitioning, but most compounds are found in both phases. Methyl tetrols, an oxidation product of isoprene, are traditionally considered to be primarily in the particle phase but are observed here to have a significant day-time gas-phase component. The measured concentration of these products in both the gas- and particle-phase is found to be strongly correlated with particle-phase sulfate, indicative of anthropogenic influence in the formation or partitioning processes. Consequently, due in part to large differences in sulfur emissions, concentrations as well as partitioning of measured isoprene products vary between the sites. We explore this dynamic further for traditional and new oxidation tracers of isoprene and monoterpenes to yield broader insight into the chemical processes behind biogenic SOA formation.