Effects of anthropogenic emissions on aerosol formation from isoprene and monoterpenes in the southeastern United States

• Type of Material: Article
• Authors: Lu Xu, Georgia Institute of Technology; Hongyu Guo, Georgia Institute of Technology; Christopher M. Boyd, Georgia Institute of Technology; Mitchel Klein, Emory University; Aikaterini Bougiatioti, Georgia Institute of Technology; Kate M. Cerully, Georgia Institute of Technology; James R. Hite, Georgia Institute of Technology; Gabriel Isaacman-VanWertz, University of California Berkeley; Nathan M. Kreisberg, Aerosol Dynamics, Inc.; Christoph Knote, National Center for Atmospheric Research; Kevin Olson, University of California Berkeley; Abigail Koss, University of Colorado; Allen H. Goldstein, University of California Berkeley; Susanne V. Hering, Aerosol Dynamics, Inc.; Joost de Gouw, University of Colorado; Karsten Baumann, Atmospheric Research and Analysis, Inc., Morrisville, NC; Shan-Hu Lee, Kent State University; Athanasios Nenes, Georgia Institute of Technology; Rodney J. Weber, Georgia Institute of Technology; Nga Lee Ng, Georgia Institute of Technology
• Language: English
• Date: 2015-01-06
• Publisher: United States National Academy of Sciences
• Publication Version: Final Published Version
• Copyright Statement: © 2015 National Academy of Sciences.
• Final Published Version (URL): http://dx.doi.org/10.1073/pnas.1417609112
• Title of Journal or Parent Work: PNAS
• Volume: 112
• Issue: 1
• Start Page: 37
• End Page: 42
• Grant/Funding Information: National Center for Atmospheric Research (NCAR) is sponsored by NSF.; We acknowledge high-performance computing support from Yellowstone (ark:/85065/d7wd3xhc) provided by NCAR's Computational and Information Systems Laboratory, sponsored by NSF.; Operation of the SEARCH network and analysis of its data collection are sponsored by the Southern Co. and Electric Power Research Institute.; SCAPE Clean Air Center is supported through US EPA Grant R834799. G.I.-V. was supported by an NSF Graduate Research Fellowship (Grant DGE 1106400), and SV-TAG data collection was funded by NSF Grant 1250569. S.-H.L. is supported by NSF (AGS-1241498).; A.B. acknowledges the research project Mediterranean Aerosol, Cloud Activation and Volatility Experiments implemented within the framework of the Action “Supporting Postdoctoral Researchers” of the Operational Program “Education and Lifelong Learning,” and is cofinanced by the European Social Fund and the Greek State.; Georgia Tech SOAS researchers were supported by National Science Foundation (NSF) Grant 1242258, US Environmental Protection Agency (EPA) STAR Grants RD-83540301 (early career) and R835410, and National Oceanic and Atmospheric Administration Climate Program Office Award NA10OAR4310102.
• Keywords: Kinetics; Water; Science & Technology - Other Topics; Photooxidation; Nitrate; Multidisciplinary Sciences; Model; Secondary organic aerosol; anthropogenic emissions; Reactive uptake; Particles; sulfate; SOA formation; Science & Technology; biogenic secondary organic aerosol; organic nitrates; fine particulate matter
• Research Categories: Environmental Sciences; Engineering, Chemical; Health Sciences, Public Health; Engineering, Biomedical; Biology, Molecular

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.