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

Monday, 15 December 2014: 2:55 PM
Lindsay Yee1, Gabriel A Isaacman1, Nathan M Kreisberg2, Yingjun Liu3, Karena A McKinney3, Suzane S. de Sá3, Scot T Martin3, M. Lizabeth Alexander4, Brett B Palm5, Weiwei Hu5, Pedro Campuzano Jost6, Douglas A Day7, Jose L Jimenez5, Juarez Viegas8, Stephen R. Springston9, Florian Wurm10, Joel Ferreira De Brito10, Paulo Artaxo10, Antonio O Manzi11, Luiz Machado12, Karla Longo12, Maria B Oliveira13, Rodrigo Augusto Ferreira de Souza13, Susanne V Hering2 and Allen H Goldstein1, (1)University of California Berkeley, Berkeley, CA, United States, (2)Aerosol Dynamics Inc., Berkeley, CA, United States, (3)Harvard University, Cambridge, MA, United States, (4)Pacific Northwest National Laboratory, Richland, WA, United States, (5)University of Colorado at Boulder, Boulder, CO, United States, (6)University of Colorado Boulder, Boulder, CO, United States, (7)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (8)Instituto Nacional de Pesquisas da Amazonia, Manaus, AM, Brazil, (9)Brookhaven National Laboratory, Upton, NY, United States, (10)USP University of Sao Paulo, São Paulo, Brazil, (11)Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil, (12)INPE National Institute for Space Research, Sao Jose dos Campos, Brazil, (13)Universidade do Estado do Amazonas, Manaus, AM, Brazil
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.