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https://doi.org/10.5194/egusphere-2023-1273
https://doi.org/10.5194/egusphere-2023-1273
20 Oct 2023
 | 20 Oct 2023

Photoenhanced sulfates formation by the heterogeneous uptake of SO2 on non-photoactive mineral dust

Chong Han, Jiawei Ma, Wangjin Yang, and Hongxing Yang

Abstract. Heterogeneous uptake of SO2 on mineral dust is a predominant formation pathway of sulfates, whereas the contribution of photo-induced SO2 oxidation to sulfates on the dust interfaces still remains unclear. Here, we investigated heterogeneous photochemical reactions of SO2 on five mineral oxides (SiO2, kaolinite, Al2O3, MgO, and CaO) without photocatalytic activity. Light significantly enhanced the uptake of SO2, and its enhancement effects negatively depended on the basicity of mineral oxides. The initial uptake coefficient (γ0,BET ) and the steady-state uptake coefficient (γs,BET ) of SO2 positively relied on light intensity, relative humidity (RH) and O2 content, while they exhibited a negative relationship with the initial SO2 concentration. Rapid sulfate formation during photo-induced heterogeneous reactions of SO2 with all mineral oxides was confirmed to be ubiquitous, and H2O and O2 played the key roles in the conversion of SO2 to sulfates. Specially, 3SO2 was suggested to be the trigger for photochemical sulfate formation. Atmospheric implications supported a potential contribution of interfacial SO2 photochemistry on non-photoactive mineral dust to atmospheric sulfate sources.  

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Chong Han, Jiawei Ma, Wangjin Yang, and Hongxing Yang

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1273', Anonymous Referee #2, 04 Dec 2023
  • RC2: 'Comment on egusphere-2023-1273', Kangwei Li, 13 Dec 2023
  • AC1: 'Comment on egusphere-2023-1273', Chong Han, 11 Jan 2024

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1273', Anonymous Referee #2, 04 Dec 2023
  • RC2: 'Comment on egusphere-2023-1273', Kangwei Li, 13 Dec 2023
  • AC1: 'Comment on egusphere-2023-1273', Chong Han, 11 Jan 2024
Chong Han, Jiawei Ma, Wangjin Yang, and Hongxing Yang
Chong Han, Jiawei Ma, Wangjin Yang, and Hongxing Yang

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Short summary
We provide direct evidences that light prominently enhances the conversion of SO2 to sulfates on non-photoactive mineral dust, where 3SO2 can act as a pivotal trigger to generate sulfates. Photochemical sulfate formation depends on H2O, O2, and basicity of mineral dust. It is suggested that the SO2 photochemistry on non-photoactive mineral dust significantly contributes to sulfates, highlighting previously unknown pathway to better explain the missing sources of atmospheric sulfates.