Chemical characterization of sesquiterpene emissions and oxidation in the Amazon using SV-TAG

 

Authors

Lindsay Yee — University of California Berkeley
Gabriel Isaacman-VanWertz — Massachusetts Institute of Technology
Rebecca Ann Wernis — University of California, Berkeley
Nathan Kreisberg — Aerosol Dynamics, Inc.
Yingjun Liu — University of California, Berkeley
Karena April McKinney — Harvard University
Suzane Simoes De Sa — Harvard University
Scot T. Martin — Harvard University
Lizabeth M Alexander — Pacific Northwest National Laboratory
Brett Palm — University of Colorado
Weiwei Hu — University of Colorado-Boulder
Pedro Campuzano-Jost — University of Colorado-Boulder
Douglas A. Day — University of Colorado, Boulder
Jose-Luis Jimenez — University of Colorado
Juarez Viegas — Los Alamos National Laboratory
Joel Brito —
Paulo Artaxo — University of Sao Paulo
Antonio Ocimar Manzi — Instituto Nacional de Pesquisas da Amazonia
Luiz Augusto Toledo Machado — INPE-CPTEC
Karla Longo — National Institute for Space Research (INPE)
Rodrigo Augusto Souza — Universidade do Estado do Amazonas
Susanne V Hering — Aerosol Dynamics Inc.
Allen Goldstein — University of California, Berkeley

Category

GoAmazon – Clouds and aerosols in Amazonia

Description

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.