Preprints
https://doi.org/10.5194/acp-2022-682
https://doi.org/10.5194/acp-2022-682
 
11 Oct 2022
11 Oct 2022
Status: this preprint is currently under review for the journal ACP.

Measurement report: Production and loss of atmospheric formaldehyde at a suburban site of Shanghai in summertime

Yizhen Wu1, Juntao Huo2, Gan Yang1, Yuwei Wang1, Lihong Wang1, Shijian Wu2, Lei Yao1, Qingyan Fu2, and Lin Wang1,3,4,5,6 Yizhen Wu et al.
  • 1Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, China
  • 2Shanghai Environmental Monitoring Center, Shanghai 200030, China
  • 3Collaborative Innovation Center of Climate Change, Nanjing, 210023, China
  • 4Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
  • 5IRDR International Center of Excellence on Risk Interconnectivity and Governance on Weather/Climate Extremes Impact and Public Health, Fudan University
  • 6National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Shanghai, China

Abstract. Formaldehyde (HCHO) is an important trace gas that affects the abundance of HO2 radicals and ozone, leads to complex photochemical processes, and yields a variety of secondary atmospheric pollutants. In a 2021 summer campaign at the Dianshan Lake (DSL) Air Quality Monitoring Supersite in a suburban area of Shanghai, China, we measured atmospheric formaldehyde (HCHO) by a commercial Aero-Laser formaldehyde monitor, methane, and a range of non-methane hydrocarbons (NMHCs). Ambient HCHO showed a significant diurnal cycle with an average concentration of 2.2±1.8 ppbv (parts per billion by volume). Secondary production of HCHO was estimated to be approximately 70 % according to HCHO/NOx. The average secondary HCHO production rate was estimated to be 0.73 ppbv h-1, with a dominant contribution from reactions between alkenes and OH radicals (66.3 %), followed by OH radical-initiated reactions with alkanes and aromatics (together 19.0 %), OH radical-initiated reactions with OVOCs (8.7 %), and ozonolysis of alkenes (6.0 %). An overall HCHO loss, including HCHO photolysis, reactions with OH radicals, and dry deposition, was estimated to be 0.49 ppbv h-1. The net HCHO production was in good agreements with the observed rate of HCHO concentration change throughout the sunny days, indicating that HCHO was approximately produced by oxidation of the 24 hydrocarbons we took into account at the DSL site during the campaign, where primary emissions and transport processes can likely be excluded. Our results suggest the important role of secondary pollution at the suburb of Shanghai, where alkenes are likely key precursors for HCHO.

Yizhen Wu et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-682', Anonymous Referee #1, 03 Nov 2022
  • RC2: 'Comment on acp-2022-682', Anonymous Referee #2, 07 Nov 2022

Yizhen Wu et al.

Data sets

Data for the study for HCHO production and loss rates in a suburban site of Shanghai.xlsx Wu, Yizhen https://doi.org/10.6084/m9.figshare.20218133.v3

Yizhen Wu et al.

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Short summary
Based on a field campaign at a suburban area of Shanghai during summer, 2021, we calculated formaldehyde (HCHO) production rates from 24 volatile organic compounds (VOCs). In addition, HCHO photolysis, reactions with OH radicals, and dry deposition, were considered for the estimation of HCHO loss rates. Our results reveal the key precursors of HCHO and suggest that HCHO wet deposition may be an important loss term in rainy days, which needs to be further investigated.
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