Preprints
https://doi.org/10.5194/egusphere-2023-2913
https://doi.org/10.5194/egusphere-2023-2913
12 Feb 2024
 | 12 Feb 2024
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Measurement Report: Elevated excess-NH3 can promote the redox reaction to produce HONO: Insights from the COVID-19 pandemic

Xinyuan Zhang, Lingling Wang, Nan Wang, Shuangliang Ma, Shenbo Wang, Ruiqin Zhang, Dong Zhang, Mingkai Wang, and Hongyu Zhang

Abstract. The incongruity between atmospheric oxidizing capacity and NOx emissions during the COVID-19 pandemic remains puzzling. Here, we show evidence from field observations of ten sites in China that there was a noticeable increase in NH3 concentrations during the COVID-19 pandemic. In addition to the meteorological conditions, the significant decrease in sulfate and nitrate concentrations enhanced the portioning of NH4+ to NH3 Such conditions enable enhanced particle pH values, which in turn accelerate the redox reactions between NO2 and SO2 to form HONO. This mechanism partly explains the enhanced atmospheric oxidizing capacity during the pandemic and highlights the importance of coordinating the control of SO2, NOx, and NH3 emissions.

Xinyuan Zhang, Lingling Wang, Nan Wang, Shuangliang Ma, Shenbo Wang, Ruiqin Zhang, Dong Zhang, Mingkai Wang, and Hongyu Zhang

Status: open (until 25 Mar 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2913', Anonymous Referee #2, 29 Feb 2024 reply
  • RC2: 'Comment on egusphere-2023-2913', Anonymous Referee #1, 03 Mar 2024 reply
Xinyuan Zhang, Lingling Wang, Nan Wang, Shuangliang Ma, Shenbo Wang, Ruiqin Zhang, Dong Zhang, Mingkai Wang, and Hongyu Zhang

Data sets

Elevated excess-NH3 can promote the redox reaction to produce HONO: Insights from the COVID-19 pandemic - Data Ruiqin Zhang https://zenodo.org/records/10273539

Xinyuan Zhang, Lingling Wang, Nan Wang, Shuangliang Ma, Shenbo Wang, Ruiqin Zhang, Dong Zhang, Mingkai Wang, and Hongyu Zhang

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Short summary
Online observational data on particulate matter composition, gaseous pollutants, and meteorological conditions from ten sites in China before and during the COVID-19 pandemic were analyzed to investigate the variation in NH3 concentrations and particle pH and explore the promoting effect of increased pH values on HONO formation. This is the first study to discuss the reasons for the increase in AOC during the pandemic from the perspective of the influence of NH3 on HONO.