Aqueous production of secondary organic aerosol from fossil-fuel emissions in winter Beijing haze
Junfeng Wang, Jianhuai Ye, Qi Zhang, Jian Zhao, Yangzhou Wu, Jingyi Li, Dantong Liu, Weijun Li, Yange Zhang, Cheng Wu, Conghui Xie, Yiming Qin, Yali Lei, Xiangpeng Huang, Jianping Guo, Pengfei Liu, Pingqing Fu, Yongjie Li, Hyun Chul Lee, Hyoungwoo Choi, Jie Zhang, Hong Liao, Mindong Chen, Yele Sun, Xinlei Ge, Scot T. Martin, Daniel J. Jacob
Abstract
) air pollution worldwide. Observations during winter haze pollution episodes in urban China show that most of this SOA originates from fossil-fuel combustion but the chemical mechanisms involved are unclear. Here we report field observations in a Beijing winter haze event that reveal fast aqueous-phase conversion of fossil-fuel primary organic aerosol (POA) to SOA at high relative humidity. Analyses of aerosol mass spectra and elemental ratios indicate that ring-breaking oxidation of POA aromatic species, leading to functionalization as carbonyls and carboxylic acids, may serve as the dominant mechanism for this SOA formation. A POA origin for SOA could explain why SOA has been decreasing over the 2013-2018 period in response to POA emission controls even as emissions of volatile organic compounds (VOCs) have remained flat.