Field and Laboratory Study of Rural Volatile Organic Compounds (VOCs) Oxidation and Secondary Organic Aerosol (SOA) Formation Utilizing Measurements of Formaldehyde and Glyoxal

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Aerosol and ozone (O3) affect human health, the environment, and climate. Oxidation of volatile organic compounds (VOCs), in particular via the hydroxyl radical (OH), is directly coupled to the formation of O3 and it contributes to secondary organic aerosol (SOA), an important component of ambient aerosol. As part of the Southern Oxidant and Aerosol Study (SOAS) the principal investigators (PIs) planned comprehensive laboratory and field studies focused on improving the detailed mechanistic understanding of the processes controlling OH and isoprene, the most important VOC, especially in rural environments. A goal is to specifically study the anthropogenic impact on biogenic VOC (BVOC) oxidation and resulting SOA formation. The project addresses the following questions: 1) How well do current mechanisms represent VOC oxidation, especially for isoprene, and in particular under low-NO conditions? 2) How well do current mechanisms/models represent OH photochemistry in view of recent findings of potential measurement interferences? 3) What are the dominant mechanisms of anthropogenic influence on rural VOC oxidation and resulting O3 and SOA formation? This research is designed to contribute ultimately to improved prediction of secondary pollutant effects from precursor emissions, and an improved ability to mitigate the anthropogenic effects of emissions on climate, human health, and the environment. The PIs also will develop a Library of Organic Standards for Atmospheric Chemistry (OSAC) that will be a publicly available online database aimed at enabling improved access to starting materials for laboratory studies and standards for calibrations.