Natural and Anthropogenically Influenced Isoprene Oxidation in Southeastern United States and Central Amazon

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  • Lindsay D. Yee, University of California at Berkeley
  • ,
  • Gabriel Isaacman-VanWertz, University of California at Berkeley
  • ,
  • Rebecca A. Wernis, University of California at Berkeley
  • ,
  • Nathan M. Kreisberg, Aerosol Dynamics Inc.
  • ,
  • Marianne Glasius
  • Matthieu Riva, University of North Carolina
  • ,
  • Jason D. Surratt, University of North Carolina
  • ,
  • Suzane S. de Sá, Harvard University
  • ,
  • Scot T. Martin, Harvard University
  • ,
  • M. Lizabeth Alexander, Environmental Molecular Sciences Laboratory
  • ,
  • Brett B. Palm, University of Colorado Boulder
  • ,
  • Weiwei Hu, University of Colorado Boulder
  • ,
  • Pedro Campuzano-Jost, University of Colorado Boulder
  • ,
  • Douglas A. Day, University of Colorado Boulder
  • ,
  • Jose L. Jimenez, University of Colorado Boulder
  • ,
  • Yingjun Liu, Harvard University
  • ,
  • Pawel K. Misztal, University of California at Berkeley
  • ,
  • Paulo Artaxo, Universidade de Sao Paulo
  • ,
  • Juarez Viegas, National Institute of Amazonian Research
  • ,
  • Antonio Manzi, National Institute of Amazonian Research
  • ,
  • Rodrigo A.F. de Souza, Universidade do Estado do Amazonas
  • ,
  • Eric S. Edgerton, Atmospheric Research & Analysis, Inc
  • ,
  • Karsten Baumann, Atmospheric Research & Analysis, Inc
  • ,
  • Allen H. Goldstein, University of California at Berkeley

Anthropogenic emissions alter secondary organic aerosol (SOA) formation chemistry from naturally emitted isoprene. We use correlations of tracers and tracer ratios to provide new perspectives on sulfate, NOx, and particle acidity influencing isoprene-derived SOA in two isoprene-rich forested environments representing clean to polluted conditions-wet and dry seasons in central Amazonia and Southeastern U.S. summer. We used a semivolatile thermal desorption aerosol gas chromatograph (SV-TAG) and filter samplers to measure SOA tracers indicative of isoprene/HO2 (2-methyltetrols, C5-alkene triols, 2-methyltetrol organosulfates) and isoprene/NOx (2-methylglyceric acid, 2-methylglyceric acid organosulfate) pathways. Summed concentrations of these tracers correlated with particulate sulfate spanning three orders of magnitude, suggesting that 1 μg m-3 reduction in sulfate corresponds with at least ∼0.5 μg m-3 reduction in isoprene-derived SOA. We also find that isoprene/NOx pathway SOA mass primarily comprises organosulfates, ∼97% in the Amazon and ∼55% in Southeastern United States. We infer under natural conditions in high isoprene emission regions that preindustrial aerosol sulfate was almost exclusively isoprene-derived organosulfates, which are traditionally thought of as representative of an anthropogenic influence. We further report the first field observations showing that particle acidity correlates positively with 2-methylglyceric acid partitioning to the gas phase and negatively with the ratio of 2-methyltetrols to C5-alkene triols.

OriginalsprogEngelsk
TidsskriftEnvironmental Science & Technology
Vol/bind54
Nummer10
Sider (fra-til)5980-5991
Antal sider12
ISSN0013-936X
DOI
StatusUdgivet - maj 2020

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