Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 5.509 IF 5.509
  • IF 5-year value: 5.689 IF 5-year 5.689
  • CiteScore value: 5.44 CiteScore 5.44
  • SNIP value: 1.519 SNIP 1.519
  • SJR value: 3.032 SJR 3.032
  • IPP value: 5.37 IPP 5.37
  • h5-index value: 86 h5-index 86
  • Scimago H index value: 161 Scimago H index 161
Volume 18, issue 5
Atmos. Chem. Phys., 18, 3641-3657, 2018
https://doi.org/10.5194/acp-18-3641-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Atmos. Chem. Phys., 18, 3641-3657, 2018
https://doi.org/10.5194/acp-18-3641-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 13 Mar 2018

Research article | 13 Mar 2018

Modeling reactive ammonia uptake by secondary organic aerosol in CMAQ: application to the continental US

Shupeng Zhu1, Jeremy R. Horne1, Julia Montoya-Aguilera2, Mallory L. Hinks2, Sergey A. Nizkorodov2, and Donald Dabdub1 Shupeng Zhu et al.
  • 1Computational Environmental Sciences Laboratory, Department of Mechanical and Aerospace Engineering, University of California, Irvine, Irvine, CA, 92697-3975, USA
  • 2Department of Chemistry, University of California, Irvine, Irvine, CA, 92697-3975, USA

Abstract. Ammonium salts such as ammonium nitrate and ammonium sulfate constitute an important fraction of the total fine particulate matter (PM2.5) mass. While the conversion of inorganic gases into particulate-phase sulfate, nitrate, and ammonium is now well understood, there is considerable uncertainty over interactions between gas-phase ammonia and secondary organic aerosols (SOAs). Observations have confirmed that ammonia can react with carbonyl compounds in SOA, forming nitrogen-containing organic compounds (NOCs). This chemistry consumes gas-phase NH3 and may therefore affect the amount of ammonium nitrate and ammonium sulfate in particulate matter (PM) as well as particle acidity. In order to investigate the importance of such reactions, a first-order loss rate for ammonia onto SOA was implemented into the Community Multiscale Air Quality (CMAQ) model based on the ammonia uptake coefficients reported in the literature. Simulations over the continental US were performed for the winter and summer of 2011 with a range of uptake coefficients (10−3–10−5). Simulation results indicate that a significant reduction in gas-phase ammonia may be possible due to its uptake onto SOA; domain-averaged ammonia concentrations decrease by 31.3% in the winter and 67.0% in the summer with the highest uptake coefficient (10−3). As a result, the concentration of particulate matter is also significantly affected, with a distinct spatial pattern over different seasons. PM concentrations decreased during the winter, largely due to the reduction in ammonium nitrate concentrations. On the other hand, PM concentrations increased during the summer due to increased biogenic SOA (BIOSOA) production resulting from enhanced acid-catalyzed uptake of isoprene-derived epoxides. Since ammonia emissions are expected to increase in the future, it is important to include NH3+SOA chemistry in air quality models.

Publications Copernicus
Download
Short summary
For the first time, the interaction between ammonia and secondary organic aerosol (SOA) is integrated in an air quality model and investigated on a national scale. Our original analysis from simulation results indicates that a significant reduction in gas-phase ammonia is possible due to its uptake onto SOA. Significant impact is also observed in the concentration of particulate matter, with a distinct spatial pattern over different seasons.
For the first time, the interaction between ammonia and secondary organic aerosol (SOA) is...
Citation
Share