1. A light - Driven acidic positive feedback mechanism of sulfate formation.
- Author
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Zhang, Chunyan, Ma, Qingxin, Zhang, Peng, Chen, Tianzeng, Wang, Yonghong, Chu, Biwu, Li, Hao, Li, Jikun, Chen, Chuncheng, Zhao, Jincai, and He, Hong
- Subjects
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SULFATE aerosols , *ATMOSPHERIC aerosols , *REACTIVE oxygen species , *SULFATES , *RADICALS (Chemistry) , *PHOTOCHEMISTRY - Abstract
As the main source of atmospheric sulfate aerosol, the aqueous-phase oxidation of SO 2 has been of great concern. Traditionally, the aqueous-phase oxidation of SO 2 is considered a consumption process of atmospheric oxidation capacity; however, we report here that •OH radicals and other reactive oxygen species (ROS) can be generated in the photochemical reactions of bulk HSO 3 − solution. This •OH production pathway results in the fast sulfate formation in the photooxidation of dissolved SO 2. The photochemical process is determined to be pH-dependent in which sulfate formation is promoted by decreasing pH. Hence, a light - driven acidic positive feedback mechanism is proposed that the oxidation of dissolved SO 2 and the formation of •OH radicals have a synergistic promoting effect. These results indicate that the photochemistry of dissolved SO 2 could be a missing source of aqueous •OH radicals as well as sulfate at regional to global scales. [Display omitted] • Aqueous-phase photooxidation of SO 2 is an important sulfate formation pathway. • Acidity promotes rather than inhibits the aqueous-phase photooxidation of SO 2. • SO 2 is not only a consumer but also an initiator of reactive oxygen species. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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