02 Aug 2021
02 Aug 2021
Status: a revised version of this preprint is currently under review for the journal ACP.

A Novel Pathway of Atmospheric Sulfate Formation Through Carbonate Radical

Yangyang Liu1,2, Yue Deng1,2, Jiarong Liu3, Xiaozhong Fang1, Tao Wang1, Kejian Li1, Kedong Gong1, Aziz U. Bacha1, Iqra Nabi1, Xiuhui Zhang3, Christian George4, and Liwu Zhang1,2 Yangyang Liu et al.
  • 1Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, P. R. China
  • 2Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, Peoples’ Republic of China
  • 3Key Laboratory of Cluster Science, Ministry of Education of China, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
  • 4Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, Villeurbanne, France

Abstract. Carbon dioxide is considered an inert gas that rarely participates in atmospheric chemical reactions. However, we show here that CO2 is involved in some important photo-oxidation reactions in the atmosphere through the formation of carbonate radicals (CO3∙-). This potentially active intermediate CO3∙- is routinely overlooked in atmospheric chemistry regarding its effect on sulfate formation. Present work demonstrates that SO2 uptake coefficient is enhanced by 17 times on mineral dust particles driven by CO3∙-. It can be produced through two routes over mineral dust surfaces: i) hydroxyl radical + CO32-; ii) holes (h+) + CO32-. Employing a suite of laboratory investigations of sulfate formation in the presence of carbonate radical on the model and authentic dust particles, field measurements of sulfate and (bi)carbonate ions within ambient PM, together with density functional theory (DFT) calculations for single electron transfer processes in terms of CO3∙--initiated S(IV) oxidation, a new role of carbonate radical in atmospheric chemistry is elucidated.

Yangyang Liu 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-2021-564', Anonymous Referee #1, 14 Aug 2021
    • AC1: 'Reply on RC1', Liwu Zhang, 23 Dec 2021
  • RC2: 'Comment on acp-2021-564', Anonymous Referee #2, 21 Oct 2021
    • AC2: 'Reply on RC2', Liwu Zhang, 23 Dec 2021

Yangyang Liu et al.

Yangyang Liu et al.


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Short summary
Both CO2 and carbonate salt works as the precursor of CO3∙-, which largely promotes sulfate formation during the daytime. This study provides the first indication that carbonate radical not only plays a role as an intermediate in tropospheric anion chemistry but also as a strong oxidant for surfacial processing of trace gas in the atmosphere. Both CO2, CO3∙- and sulfate receive great attention from communities looking at the environment, atmosphere, aerosol, and photochemistry.