Fine Particle pH and Sensitivity to NH3 and HNO3 over South Korea During KORUS-AQ
Ifayoyinsola Ibikunle,
Andreas Beyersdorf,
Pedro Campuzano-Jost,
Chelsea Corr,
John D. Crounse,
Jack Dibb,
Glenn Diskin,
Greg Huey,
Jose-Luis Jimenez,
Michelle J. Kim,
Benjamin A. Nault,
Eric Scheuer,
Alex Teng,
Paul O. Wennberg,
Bruce Anderson,
James Crawford,
Rodney Weber,
Athanasios Nenes
Affiliations
Ifayoyinsola Ibikunle
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
Andreas Beyersdorf
NASA Langley Research Center, Hampton, VA 23681, USA
Pedro Campuzano-Jost
Department of Chemistry, University of Colorado, Boulder, CO 80309, USA; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA
Chelsea Corr
NASA Langley Research Center, Hampton, VA 23681, USA; Currently at Colorado State University
John D. Crounse
California Institute of Technology, Pasadena, CA 91125
Jack Dibb
Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA
Glenn Diskin
NASA Ames Research Center, Moffett Field, CA 94035, USA
Greg Huey
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
Jose-Luis Jimenez
Department of Chemistry, University of Colorado, Boulder, CO 80309, USA; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA
Michelle J. Kim
California Institute of Technology, Pasadena, CA 91125
Benjamin A. Nault
Department of Chemistry, University of Colorado, Boulder, CO 80309, USA; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA; Currently at Center for Aerosol and Cloud Chemistry, Aerodyne Research Inc., Billerica, MA, USA
Eric Scheuer
Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA
Alex Teng
California Institute of Technology, Pasadena, CA 91125
Paul O. Wennberg
California Institute of Technology, Pasadena, CA 91125
Bruce Anderson
NASA Langley Research Center, Hampton, VA 23681, USA
James Crawford
NASA Langley Research Center, Hampton, VA 23681, USA
Rodney Weber
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA; School of Architecture, Civil & Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland; Center for the Study of Air Quality and Climate Change, Institute for Chemical Engineering Sciences, Foundation for Research and Technology Hellas, Patras, GR-26504, Greece
Using a new approach that constrains thermodynamic modeling of aerosol composition with measured gas-to-particle partitioning of inorganic nitrate, we estimate the acidity levels for aerosol sampled in the South Korean planetary boundary layer during the NASA/NIER KORUS-AQ field campaign. The pH (mean ± 1σ = 2.43±0.68) and aerosol liquid water content determined were then used to determine the ‘chemical regime’ of the inorganic fraction of particulate matter (PM) sensitivity to ammonia and nitrate availability. We found that the aerosol formation is always sensitive to HNO3 levels, especially in highly polluted regions, while it is only exclusively sensitive to NH3 in some rural/remote regions. Nitrate levels are further promoted because dry deposition velocity is low and allows its accumulation in the boundary layer. Because of this, HNO3 reductions achieved by NOX controls prove to be the most effective approach for all conditions examined, and that NH3 emissions can only partially affect PM reduction for the specific season and region. Despite the benefits of controlling PM formation to reduce ammonium-nitrate aerosol and PM mass, changes in the acidity domain can significantly affect other processes and sources of aerosol toxicity (e.g. solubilization of Fe, Cu and other metals) as well as the deposition patterns of these trace species and reactive nitrogen.
