Analysis of observations over South Korea during the NASA/NIER
KORUS-AQ field campaign show that aerosol is fairly acidic (mean pH 2.43 ± 0.68). 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 accumulate because dry deposition velocity is low. HNO3 reductions achieved by NOx controls can be the most effective PM reduction strategy for all conditions observed.
Analysis of observations over South Korea during the NASA/NIER
KORUS-AQ field campaign show...
1School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
2NASA Langley Research Center, Hampton, VA 23681, USA
3Department of Chemistry, University of Colorado, Boulder, CO 80309, USA
4Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA
5California Institute of Technology, Pasadena, CA 91125
6Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA
7NASA Ames Research Center, Moffett Field, CA 94035, USA
8School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
9School of Architecture, Civil & Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
10Center for the Study of Air Quality and Climate Change, Institute for Chemical Engineering Sciences, Foundation for Research and Technology Hellas, Patras, GR-26504, Greece
acurrently at: Colorado State University
1School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
2NASA Langley Research Center, Hampton, VA 23681, USA
3Department of Chemistry, University of Colorado, Boulder, CO 80309, USA
4Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA
5California Institute of Technology, Pasadena, CA 91125
6Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA
7NASA Ames Research Center, Moffett Field, CA 94035, USA
8School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
9School of Architecture, Civil & Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
10Center for the Study of Air Quality and Climate Change, Institute for Chemical Engineering Sciences, Foundation for Research and Technology Hellas, Patras, GR-26504, Greece
Received: 24 May 2020 – Accepted for review: 19 Jul 2020 – Discussion started: 21 Jul 2020
Abstract. 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 (such as e.g., solubilization of Fe, Cu and other metals) as well as the deposition patterns of these trace species and reactive nitrate.
Analysis of observations over South Korea during the NASA/NIER
KORUS-AQ field campaign show that aerosol is fairly acidic (mean pH 2.43 ± 0.68). 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 accumulate because dry deposition velocity is low. HNO3 reductions achieved by NOx controls can be the most effective PM reduction strategy for all conditions observed.
Analysis of observations over South Korea during the NASA/NIER
KORUS-AQ field campaign show...