AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Embracing Complexity: Deciphering Origins and Transformations of Atmospheric Organics through Speciated Measurements
ALLEN H. GOLDSTEIN, University of California, Berkeley
Abstract Number: 451 Working Group: Invited by Conference Chair
Abstract Organic material accounts for a large fraction of atmospheric aerosol, with the majority being secondary organic aerosol (SOA) formed through oxidation processes. Primary emissions leading to SOA include thousands of chemicals from a variety of natural and anthropogenic sources ranging over approximately 15 orders of magnitude of volatility. As organics are oxidized they fragment to form smaller volatiles or add functionality leading to SOA formation, dramatically increasing the complexity of compounds present. A continuing challenge in aerosol research is to elucidate the sources, structure, chemistry, fate, climate and health impacts of these organic atmospheric constituents.
The complex chemical composition of organic aerosols presents unique measurement challenges. Dr. Goldstein’s group and close collaborators have developed the Thermal Desorption Aerosol Gas chromatograph (TAG) system for hourly in-situ speciation of a wide range of primary and secondary organic compounds in aerosols. This instrument combines a particle collector with thermal desorption followed by GCMS detection to provide hourly separation, identification, and quantification of organic constituents at the molecular level. We incorporated two-dimensional chromatography (GCxGC), providing dramatically enhanced speciation. We developed a semivolatile collection and analysis system that allows simultaneous measurement of specific organics in the gas and particle phases, enabling analysis of their partitioning. We also developed a combined TAG-AMS (Aerosol Mass Spectrometer) instrument for simultaneous measurements of the total and speciated aerosol composition. We are currently exploring soft ionization with vacuum ultraviolet radiation using a high resolution time of flight mass spectrometer (GCxGC/VUV-HRTOFMS) to more fully separate and identify compounds in complex mixtures such as diesel fuel, motor oil, fire emissions, in controlled oxidation studies, and in ambient samples. This talk will review recent developments (TAG, 2DTAG, SVTAG, TAG-AMS, GCxGC/VUV-HRTOFMS), and present new atmospheric observations, source characterizations, and controlled oxidation studies to more fully characterize atmospheric organic sources and transformation processes.