title: Effects of anthropogenic emissions on aerosol formation from isoprene and monoterpenes in the southeastern United States.
abstract: Secondary organic aerosol (SOA) constitutes a substantial fraction of fine particulate matter and has important impacts on climate and human health. The extent to which human activities alter SOA formation from biogenic emissions in the atmosphere is largely undetermined. Here, we present direct observational evidence on the magnitude of anthropogenic influence on biogenic SOA formation based on comprehensive ambient measurements in the southeastern United States (US). Multiple high-time-resolution mass spectrometry organic aerosol measurements were made during different seasons at various locations, including urban and rural sites in the greater Atlanta area and Centreville in rural Alabama. Our results provide a quantitative understanding of the roles of anthropogenic SO2 and NOx in ambient SOA formation. We show that isoprene-derived SOA is directly mediated by the abundance of sulfate, instead of the particle water content and/or particle acidity as suggested by prior laboratory studies. Anthropogenic NOx is shown to enhance nighttime SOA formation via nitrate radical oxidation of monoterpenes, resulting in the formation of condensable organic nitrates. Together, anthropogenic sulfate and NOx can mediate 43-70% of total measured organic aerosol (29-49% of submicron particulate matter, PM1) in the southeastern US during summer. These measurements imply that future reduction in SO2 and NOx emissions can considerably reduce the SOA burden in the southeastern US. Updating current modeling frameworks with these observational constraints will also lead to more accurate treatment of aerosol formation for regions with substantial anthropogenic-biogenic interactions and consequently improve air quality and climate simulations.
authors.affiliation: Schools of Chemical and Biomolecular Engineering and.
authors.forename: Lu
authors.initials: L
authors.lastname: Xu
authors.affiliation: Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332;
authors.forename: Hongyu
authors.initials: H
authors.lastname: Guo
authors.affiliation: Schools of Chemical and Biomolecular Engineering and.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Boyd
authors.affiliation: Rollins School of Public Health, Emory University, Atlanta, GA 30322;
authors.forename: Mitchel
authors.initials: M
authors.lastname: Klein
authors.affiliation: Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332; Laser Remote Sensing Laboratory, National Technical University of Athens, 15780 Zografou, Greece;
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Bougiatioti
authors.affiliation: Schools of Chemical and Biomolecular Engineering and.
authors.forename: Kate M
authors.initials: KM
authors.lastname: Cerully
authors.affiliation: Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332;
authors.forename: James R
authors.initials: JR
authors.lastname: Hite
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720;
authors.forename: Gabriel
authors.identifier: http://orcid.org/0000-0002-3717-4798
authors.initials: G
authors.lastname: Isaacman-VanWertz
authors.affiliation: Aerosol Dynamics, Inc., Berkeley, CA 94710;
authors.forename: Nathan M
authors.initials: NM
authors.lastname: Kreisberg
authors.affiliation: Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, CO 80307;
authors.forename: Christoph
authors.initials: C
authors.lastname: Knote
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720;
authors.forename: Kevin
authors.initials: K
authors.lastname: Olson
authors.affiliation: NOAA Earth System Research Laboratory, Boulder, CO 80305; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309;
authors.forename: Abigail
authors.initials: A
authors.lastname: Koss
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720; Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720;
authors.forename: Allen H
authors.initials: AH
authors.lastname: Goldstein
authors.affiliation: Aerosol Dynamics, Inc., Berkeley, CA 94710;
authors.forename: Susanne V
authors.initials: SV
authors.lastname: Hering
authors.affiliation: NOAA Earth System Research Laboratory, Boulder, CO 80305; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309;
authors.forename: Joost
authors.initials: J
authors.lastname: de Gouw
authors.affiliation: Atmospheric Research and Analysis, Inc., Morrisville, NC 27560;
authors.forename: Karsten
authors.initials: K
authors.lastname: Baumann
authors.affiliation: College of Public Health, Kent State University, Kent, OH 44242; and.
authors.forename: Shan-Hu
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Schools of Chemical and Biomolecular Engineering and Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332; Institute of Chemical Engineering Sciences, Foundation for Research, GR-26504 Patras, Greece.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Nenes
authors.affiliation: Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332;
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Weber
authors.affiliation: Schools of Chemical and Biomolecular Engineering and Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332; ng@chbe.gatech.edu.
authors.forename: Nga Lee
authors.initials: NL
authors.lastname: Ng
keywords: anthropogenic emissions; biogenic secondary organic aerosol; fine particulate matter; organic nitrates; sulfate