Fast sulfate formation from oxidation of SO2 by NO2 and HONO observed in Beijing haze

Junfeng Wang; Jingyi Li; Jianhuai Ye; Jian Zhao; Yangzhou Wu; Jianlin Hu; Dantong Liu; Dongyang Nie; Fuzhen Shen; Xiangpeng Huang; Dan Dan Huang; Dongsheng Ji; Xu Sun; Weiqi Xu; Jianping Guo; Shaojie Song; Yiming Qin; Pengfei Liu; Jay R Turner; Hyun Chul Lee; Sungwoo Hwang; Hong Liao; Scot T Martin; Qi Zhang; Mindong Chen; Yele Sun; Xinlei Ge; Daniel J Jacob

doi:10.1038/s41467-020-16683-x

Fast sulfate formation from oxidation of SO₂ by NO₂ and HONO observed in Beijing haze

Nat Commun. 2020 Jun 5;11(1):2844. doi: 10.1038/s41467-020-16683-x.

Authors

Junfeng Wang^#^{1

2}, Jingyi Li^#¹, Jianhuai Ye^#², Jian Zhao³, Yangzhou Wu^{1

4}, Jianlin Hu¹, Dantong Liu⁴, Dongyang Nie^{1

5}, Fuzhen Shen¹, Xiangpeng Huang¹, Dan Dan Huang⁶, Dongsheng Ji³, Xu Sun⁷, Weiqi Xu³, Jianping Guo⁸, Shaojie Song², Yiming Qin², Pengfei Liu², Jay R Turner⁹, Hyun Chul Lee¹⁰, Sungwoo Hwang¹⁰, Hong Liao¹, Scot T Martin², Qi Zhang¹¹, Mindong Chen¹, Yele Sun³, Xinlei Ge¹², Daniel J Jacob¹³

Affiliations

¹ Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, 210044, China.
² John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
³ State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China.
⁴ Department of Atmospheric Sciences, School of Earth Sciences, Zhejiang University, Hangzhou, 310027, China.
⁵ School of Atmospheric Sciences, Nanjing University, Nanjing, 210023, China.
⁶ State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai, 200233, China.
⁷ State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
⁸ State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing, 100081, China.
⁹ Department of Energy, Environmental and Chemical Engineering, Washington University in Saint Louis, St. Louis, MO, 63130, USA.
¹⁰ Samsung Advanced Institute of Technology, Suwon-si, Gyeonggi-do, 16678, Republic of Korea.
¹¹ Department of Environmental Toxicology, University of California Davis, Davis, CA, 95616, USA.
¹² Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, 210044, China. caxinra@163.com.
¹³ John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA. djacob@fas.harvard.edu.

^# Contributed equally.

Abstract

Severe events of wintertime particulate air pollution in Beijing (winter haze) are associated with high relative humidity (RH) and fast production of particulate sulfate from the oxidation of sulfur dioxide (SO₂) emitted by coal combustion. There has been considerable debate regarding the mechanism for SO₂ oxidation. Here we show evidence from field observations of a haze event that rapid oxidation of SO₂ by nitrogen dioxide (NO₂) and nitrous acid (HONO) takes place, the latter producing nitrous oxide (N₂O). Sulfate shifts to larger particle sizes during the event, indicative of fog/cloud processing. Fog and cloud readily form under winter haze conditions, leading to high liquid water contents with high pH (>5.5) from elevated ammonia. Such conditions enable fast aqueous-phase oxidation of SO₂ by NO₂, producing HONO which can in turn oxidize SO₂ to yield N₂O.This mechanism could provide an explanation for sulfate formation under some winter haze conditions.

Publication types

Research Support, Non-U.S. Gov't