Effects of anthropogenic emissions on aerosol formation from isoprene and monoterpenes in the southeastern United States
Year: 2014
Type: article
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: Lu Xu, Hongyu Guo, Christopher M. Boyd, Mitchel Klein, Aikaterini Bougiatioti, Kate M. Cerully, James R. Hite, Gabriel Isaacman-VanWertz, Nathan M. Kreisberg, Christoph Knote, Kevin Olson, Abigail Koss, Allen H. Goldstein, Susanne V. Hering, Joost de Gouw, Karsten Baumann, Shan-Hu Lee, Athanasios Nenes, Rodney J. Weber, Nga Lee Ng
Institutions: Georgia Institute of Technology, Emory University, National Technical University of Athens, University of California, Berkeley, Aerosol Dynamics (United States), NSF National Center for Atmospheric Research, Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, NOAA Earth System Research Laboratory, Kent State University, FORTH Institute of Chemical Engineering Sciences
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
Awards: G1472013983, G1695350352, Graduate Research Fellowship Program, Measurements of Amines during the Southern Oxidant and Aerosol Study (SOAS) Field Campaign, G621447044, Contribution of Biogenic Volatile Organic Compounds to Organic Aerosol Formation in the Presence and Absence of Anthropogenic Pollution, Collaborative Research: Atmospheric Mixed Phase Chemistry for Improved Climate Predictions: Field Measurements and Modeling of the Southern Oxidant and Aerosol Study, G8803434230
OpenAlex ID: W2079702179