Preprints
https://doi.org/10.5194/acp-2021-61
https://doi.org/10.5194/acp-2021-61

  22 Jan 2021

22 Jan 2021

Review status: a revised version of this preprint was accepted for the journal ACP and is expected to appear here in due course.

SO2 and NH3 emissions enhance organosulfur compounds and fine particles formation from the photooxidation of a typical aromatic hydrocarbon

Zhaomin Yang1, Li Xu1, Narcisse T. Tsona1, Jianlong Li1, Xin Luo2, and Lin Du1 Zhaomin Yang et al.
  • 1Environment Research Institute, Shandong University, Qingdao, 266237, China
  • 2Technology Center of Qingdao Customs, Qingdao, 266003, China

Abstract. Although atmospheric SO2 and NH3 levels can affect secondary aerosol formation, the influenced extent of their impact and their detailed driving mechanisms are not well understood. The focus of the present study is to examine the chemical compositions and formation mechanisms of secondary organic aerosols (SOA) from 1,2,4-trimethylbenzene (TMB) photooxidation influenced by SO2 and/or NH3. Here, we showed that SO2 emission could considerably enhance aerosol particle formation due to SO2-induced sulfates generation and acid-catalyzed heterogeneous reaction. Orbitrap mass spectrometry (MS) measurements revealed the generation of not only typical TMB products but also hitherto unidentified organosulfates (OSs) in SO2-added experiments. The OSs designated as unknown origin in earlier field measurements were also detected in TMB SOA, indicating that atmospheric OSs might be also originated from TMB photooxidation. For NH3-involved experiments, results demonstrated a positive correlation between NH3 levels and particle volume as well as number concentrations. The effects of NH3 on SOA composition was slight under SO2-free conditions but stronger in the presence of SO2. A series of multifunctional products with carbonyl, alcohols, and nitrate functional groups were tentatively characterized in NH3-involved experiments based on infrared spectra and HRMS analysis. Plausible formation pathways were proposed for detected products in the particle-phase. The volatility distributions of products, estimated using parameterization methods, suggested that the detected products gradually condense onto the nucleation particles to contribute to aerosol formation and growth. Our results suggest that strict control of SO2 and NH3 emissions might remarkably reduce organosulfates and secondary aerosol burden in the atmosphere. Updating the aromatic oxidation mechanism in models could result in more accurate treatment of particles formation for urban regions with considerable SO2, NH3, and aromatics emissions.

Zhaomin Yang et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-61', Anonymous Referee #1, 07 Feb 2021
  • RC2: 'Comment on acp-2021-61', Anonymous Referee #2, 23 Feb 2021
  • RC3: 'Comment on acp-2021-61', Anonymous Referee #3, 25 Feb 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-61', Anonymous Referee #1, 07 Feb 2021
  • RC2: 'Comment on acp-2021-61', Anonymous Referee #2, 23 Feb 2021
  • RC3: 'Comment on acp-2021-61', Anonymous Referee #3, 25 Feb 2021

Zhaomin Yang et al.

Zhaomin Yang et al.

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Short summary
The promotion effects of SO2 and NH3 on aerosol particles and organosulfur compounds formation from 1,2,4-trimethylbenzene (TMB) photooxidation were observed for the first time. The enhanced organosulfur compounds included hitherto unidentified aromatic sulfonates and organosulfates, which were produced via acid-driven heterogeneous chemistry of hydroperoxides. The production of organosulfur compounds might provide a new pathway for the fate of TMB in regions with considerable SO2 emissions.
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