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List of Abstracts 223Robinson, A.L. et al. (2007) Rethinking Organic Aerosols: Semivolatile Emissions and PhotochemicalAging, Science, 315, 1259-1262.Transformation 1.5 ID:4571 15:15Are Aromatic Hydrocarbons Generated from the Atmospheric Oxidation of Biogenic HydrocarbonsSuch as α-Pinene?Aline Gratien, Stanley N. Johnson, Michael J. Ezell, Matt Dawson, Raffeal Bennett, Barbara J. Finlayson-PittsDepartment of Chemistry, University of California Irvine, Irvine, CA 92697-2025Contact: agratien@uci.eduAnthropogenic sources release into the troposphere a wide range of volatile organic compounds (VOC),including aromatic hydrocarbons. Biogenic volatile organic compounds (BVOCs) are also widely emitted,and are estimated to account for approximately 90% of total hydrocarbon emissions. When released into thetroposphere, these BVOC and VOC undergo chemical oxidation, e.g. by hydroxyl radicals (OH) and ozone(O 3 ) during daytime, and by nitrate radicals (NO 3 ) and ozone at night. Care must be taken to distinguishdirect anthropogenic emissions and products from BVOC and its oxidation products. For example, anaromatic hydrocarbon, p-cymene, was recently reported in the air above a forest canopy that had significantemissions of α-pinene, and its concentration increased as a function of altitude, suggesting its possibleformation in the atmosphere. Consequently, the aim of the present study was to see if p-cymene is generatedor not by the oxidation of α-pinene. Oxidation of α-pinene by O 3 , NO 3 and OH has been studied at 1 atm airunder dry conditions, at high relative humidity (70% RH), and with deliquesced sodium bisulfate (acidsource) on the walls of a Teflon reaction chamber (100 L). Reactants and products were measured using GC-MS. The results of the work will be presented and the atmospheric implications discussed.iCACGP-IGAC 2010 14 July, 2010