10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Heterogeneity in the Concentration Distribution of Semi-Volatile Organic Compounds in the Surface Boundary Layer over the Tropical Forest in Central Amazonia
JIANHUAI YE, Patrícia C. Guimarães, Carla E. Batista, Igor O. Ribeiro, Adan Medeiros, Matthew Stewart, Yaowei Li, Matheus A. Tomoto, Daniel Wang, Dasa Gu, Rafael L. Oliveira, Sérgio Duvoisin Junior, Karena McKinney, Alex Guenther, Rodrigo A. F. de Souza, Scot T. Martin, Harvard University
Abstract Number: 1010 Working Group: Remote/Regional Atmospheric Aerosol
Abstract Biogenic volatile organic compounds (BVOCs) significantly contribute to atmospheric oxidation capacity, and act as crucial parts in the carbon cycle of the atmosphere. Amazonia, the world’s largest rainforest ecosystem, is one of the major sources of global BVOC emissions. Current atmospheric chemistry models have failed to accurately simulate BVOC oxidations over heterogeneous land surfaces, such as Amazon rainforest. Discrepancy has been observed in field studies between modeled and measured concentrations of BVOCs, as well as corresponding oxidants (e.g., hydroxyl radical). One of the reasons leading to this discrepancy is the non-uniform distribution of atmospheric BVOC species and their oxidants, owing to inefficient turbulent mixing and variable emissions (i.e., BVOC types and concentrations) over different forest sub-types. Semi-volatile organic compounds (SVOCs) formed from oxidation of BVOCs, are key precursors to the production of atmospheric particulate matter which plays a pivotal role in global climate change. Uneven BVOC distribution can lead to segregation of SVOC formations, resulting in segregated PM production in the atmospheric boundary layer over Amazonia. In this study, the hypothesis of SVOC heterogeneity is examined. The temporal and spatial distribution profiles of SVOCs from isoprene and monoterpene oxidation in Amazonia are investigated. Air samples are collected using unmanned aerial vehicle (UAV) technique, an emerging frontier in atmospheric chemistry. SVOCs are sampled by a custom-built sampler equipped with sorbent cartridges on the UAV, followed by chemical analysis using thermal desorption gas chromatography-mass spectrometry (TD-GC/MS) coupled with an online derivatization module. The SVOC data set obtained from this study, linking the diversity among VOCs and atmospheric PM production, will be used to better constrain current atmospheric chemistry models and provide insights on regional and global chemical transport in Amazonia.