Anthropogenic Influence on Oxidative Capacity and BVOC Oxidation During GoAmazon 2014

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This project is focused on improving the mechanistic understanding of processes controlling the oxidative capacity of the atmosphere in the Amazon, a region with high concentrations of biogenic volatile organic compounds (BVOC), and investigating the anthropogenic influences on these processes. These objectives will be pursued through a field study in the central Amazon downwind of the industrial city of Manaus (population 2 million), Brazil, during two intensive operating periods (IOPs) (Feb/Mar and Aug/Oct 2014). The Amazon is a good location for this work since the intense sunlight, high BVOC emissions dominated by isoprene, and sustained high OH concentrations result in rapid photochemical processing and formation of secondary organic aerosol (SOA).In-situ measurements of BVOC oxidation products, such as glyoxal, methylgloxal, and formaldehyde, that have different OH-dependent formation or loss pathways, will be used along oxidation product ratios and modeling efforts to determine the key chemical mechanisms of BVOC oxidation during both the wet and dry seasons. During the wet season, measurements at the site are expected to provide data related to "clean" conditions, while during the dry season the polluted plume from Manaus is expected to impact the site, providing information about the anthropogenic influence (especially that of NOx) on BVOC oxidation. A better understanding of these mechanisms will clarify the extent to which hydroxyl radicals are recycled following reactions with BVOC in tropical forests. This research will to contribute to improved global/regional prediction of greenhouse-gas lifetimes and aerosol effects from precursor emissions on climate, air quality, public health, and the environment. It is an important contribution to the larger GoAmazon-2014 campaign supported by the U.S. Department of Energy and the government of Brazil to look at the coupled atmosphere-cloud-terrestrial tropical systems.