AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Observational Constraints on Terpene Oxidation in the Amazon Using Speciated Measurements from SV-TAG
LINDSAY YEE, Gabriel Isaacman-VanWertz, Rebecca Wernis, Nathan Kreisberg, Yingjun Liu, Karena McKinney, Suzane Simoes de Sa, Scot Martin, Lizabeth Alexander, Brett Palm, Weiwei Hu, Pedro Campuzano-Jost, Douglas Day, Jose-Luis Jimenez, Juarez Viegas, Stephen Springston, Florian Wurm, Joel Brito, Paulo Artaxo, Antonio O. Manzi, Luiz Machado, Maria Oliveira, Rodrigo A. F. Souza, Susanne Hering, Allen H. Goldstein, University of California at Berkeley, Berkeley, CA, USA
Abstract Number: 564 Working Group: Remote and Regional Atmospheric Aerosols
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). 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) 2014/5 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. Several sesquiterpenes present in ambient data were found to overlap with the sesquiterpene composition in essential oils from the Copaiba tree (Copaifera officinalis Jacq. L.), commonly known as the “diesel tree” in the Amazon, suggesting that it and related vegetation may be potential sources of BVOC emissions in the Amazon. We observe sesquiterpenes at levels of tens of pptv, and they are anti-correlated with ozone. We estimate that from the observed sesquiterpene and monoterpene concentrations, sesquiterpenes would account for more olefin-channel ozone sink (loss). We then compare the ambient data with that from laboratory focused sesquiterpene oxidation experiments to identify new tracers for ambient sesquiterpene oxidation. We report gas-particle partitioning of speciated terpene oxidation products and explore relative contributions of isoprene and terpene oxidation products to SOA formation by combining SV-TAG measurements with those from an additional suite of VOC and particle measurements deployed in the Amazon.