Persistent sulfate formation from London Fog to Chinese haze

Gehui Wang, Renyi Zhang, Mario E Gomez, Lingxiao Yang, Misti Levy Zamora, Min Hu, Yun Lin, Jianfei Peng, Song Guo, Jingjing Meng, Jianjun Li, Chunlei Cheng, Tafeng Hu, Yanqin Ren, Yuesi Wang, Jian Gao, Junji Cao, Zhisheng An, Weijian Zhou, Guohui LiJiayuan Wang, Pengfei Tian, Wilmarie Marrero-Ortiz, Jeremiah Secrest, Zhuofei Du, Jing Zheng, Dongjie Shang, Limin Zeng, Min Shao, Weigang Wang, Yao Huang, Yuan Wang, Yujiao Zhu, Yixin Li, Jiaxi Hu, Bowen Pan, Li Cai, Yuting Cheng, Yuemeng Ji, Fang Zhang, Daniel Rosenfeld, Peter S Liss, Robert A Duce, Charles E Kolb, Mario J Molina

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Abstract

Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models consistently underpredict sulfate levels under diverse environmental conditions. From atmospheric measurements in two Chinese megacities and complementary laboratory experiments, we show that the aqueous oxidation of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atmospheric conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidation process leads to large sulfate production rates and promotes formation of nitrate and organic matter on aqueous particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addition to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate production mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world.

Original languageEnglish
Pages (from-to)13630-13635
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America (PNAS)
Volume113
Issue number48
DOIs
Publication statusPublished - 29 Nov 2016

Keywords

  • sulfate aerosol
  • severe haze
  • pollution
  • human health
  • climate

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