Observational Constraints on Terpene Oxidation with and without Anthropogenic Influence in the Amazon using Speciated Measurements from SV-TAG

Lindsay Yee1, Gabriel A Isaacman-VanWertz2, Nathan M Kreisberg3, Yingjun Liu4, Karena A McKinney5, Suzane S de Sá5, Scot T Martin6, M. Lizabeth L Alexander7, Brett B Palm8, Weiwei Hu9, Pedro Campuzano-Jost10, Doug A Day11, Jose L Jimenez12, Juarez Viegas13, Stephen R. Springston14, Florian Wurm15, Joel Ferreira De Brito15, Paulo Artaxo15, Antonio O Manzi16, Luiz Machado17, Karla Longo17, Maria B Oliveira18, Rodrigo Augusto Ferreira de Souza18, Susanne V Hering3 and Allen H Goldstein19, (1)University of California Berkeley, Department of Environmental Science, Policy, & Management, Berkeley, CA, United States, (2)University of California Berkeley, Berkeley, CA, United States, (3)Aerosol Dynamics Inc., Berkeley, CA, United States, (4)Harvard University, Cambridge, United States, (5)Harvard University, School of Engineering and Applied Sciences, Cambridge, MA, United States, (6)Harvard University, Department of Earth and Planetary Sciences, Cambridge, MA, United States, (7)Pacific Northwest National Laboratory, Richland, WA, United States, (8)University of Colorado at Boulder, Boulder, United States, (9)Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China, (10)University of Colorado Boulder, Department of Chemistry and Cooperative Institute for Research in Environmental Sciences, Boulder, United States, (11)Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, United States, (12)Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder, United States, (13)Instituto Nacional de Pesquisas da Amazonia, Manaus, AM, Brazil, (14)Brookhaven National Laboratory, Upton, NY, United States, (15)USP University of Sao Paulo, São Paulo, Brazil, (16)Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil, (17)INPE National Institute for Space Research, Sao Jose dos Campos, Brazil, (18)Universidade do Estado do Amazonas, Manaus, AM, Brazil, (19)University of California Berkeley, Department of Civil & Environmental Engineering, Berkeley, CA, United States
Abstract:
Biogenic volatile organic compounds (BVOCs) from the Amazon forest represent the largest regional source of organic carbon emissions to the atmosphere. These BVOC emissions dominantly consist of volatile and semi-volatile terpenoid compounds that undergo chemical transformations in the atmosphere to form oxygenated condensable gases and secondary organic aerosol (SOA). However, the oxidation pathways of these compounds are still not well understood, and are expected to differ significantly between “pristine” conditions, as is common in Amazonia, and polluted conditions caused by emissions from growing cities. Our focus is to elucidate how anthropogenic emissions influence BVOC chemistry and BSOA formation through speciated measurements of their oxidation products. We have deployed the Semi-Volatile Thermal desorption Aerosol Gas Chromatograph (SV-TAG) at the rural T3 site located west of the urban center of Manaus, Brazil as part of the Green Ocean Amazon (GoAmazon) 2014 field campaign to measure hourly concentrations of semi-volatile BVOCs and their oxidation products during the wet and dry seasons. Primary BVOC concentrations measured by the SV-TAG include sesquiterpenes and diterpenes, which have rarely been speciated with high time-resolution. We observe sesquiterpenes to be anti-correlated with ozone, indicative of sesquiterpene oxidation playing a major role in the regional oxidant budget. The role of sesquiterpenes in atmospheric SOA formation are of interest due to their high aerosol yields and high reactivity with ozone, relative to more commonly measured BVOCs (e.g. monoterpenes). We explore relative concentrations of sesquiterpenes and monoterpenes and their roles as precursors to SOA formation by combining SV-TAG measurements with those from an additional suite of VOC and particle measurements deployed in the Amazon. We also report the first ever hourly observations of the gas-particle partitioning of speciated terpene oxidation products in the Amazon and discuss their implications for photochemical transformation and SOA formation in the region.
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