Atmospheric Photosensitization: A New Pathway for Sulfate Formation

Xinke Wang, Rachel Gemayel, Nathalie Hayeck, Sebastien Perrier, Nicolas Charbonnel, Caihong Xu, Hui Chen, Chao Zhu, Liwu Zhang, Lin Wang, Sergey A. Nizkorodov, Xinming Wang, Zhe Wang, Tao Wang, Abdelwahid Mellouki, Matthieu Riva, Jianmin Chen, Christian George

Research output: Journal article publicationJournal articleAcademic researchpeer-review

55 Citations (Scopus)


Northern China is regularly subjected to intense wintertime "haze events", with high levels of fine particles that threaten millions of inhabitants. While sulfate is a known major component of these fine haze particles, its formation mechanism remains unclear especially under highly polluted conditions, with state-of-the-art air quality models unable to reproduce or predict field observations. These haze conditions are generally characterized by simultaneous high emissions of SO2 and photosensitizing materials. In this study, we find that the excited triplet states of photosensitizers could induce a direct photosensitized oxidation of hydrated SO2 and bisulfite into sulfate S(VI) through energy transfer, electron transfer, or hydrogen atom abstraction. This photosensitized pathway appears to be a new and ubiquitous chemical route for atmospheric sulfate production. Compared to other aqueous-phase sulfate formation pathways with ozone, hydrogen peroxide, nitrogen dioxide, or transition-metal ions, the results also show that this photosensitized oxidation of S(IV) could make an important contribution to aerosol sulfate formation in Asian countries, particularly in China.

Original languageEnglish
Pages (from-to)3114-3120
Number of pages7
JournalEnvironmental Science and Technology
Issue number6
Publication statusPublished - 17 Mar 2020

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry


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