Changes in Aerosol Chemistry From 2014 to 2016 in Winter in Beijing: Insights From High‐Resolution Aerosol Mass Spectrometry

作者：Weiqi Xu, Yele Sun, Qingqing Wang, Jian Zhao, Junfeng Wang, Xinlei Ge, Conghui Xie, Wei Zhou, Wei Du, Jie Li, Pingqing Fu, Zifa Wang, Douglas R. Worsnop, Hugh Coe · 发表于：Journal of Geophysical Research Atmospheres · 年份：2018 · 被引用次数：300 · 研究领域：Atmospheric chemistry and aerosols、Air Quality and Health Impacts、Atmospheric aerosols and clouds

Abstract Air quality has been continuously improved in recent years in Beijing, yet severe haze episodes still frequently occur in winter. Here we deployed an Aerodyne high‐resolution aerosol mass spectrometer in two winter seasons during the same period to investigate the changes in aerosol chemistry from 2014 to 2016 in Beijing. Compared to 2014, submicron aerosol (PM1) species showed ubiquitous increases in mass concentrations by 10–130% in winter 2016, of which nitrate showed the largest increase among all aerosol species leading to a much higher NO3/SO4 ratio in 2016 (1.36 ± 0.90) than 2014 (0.72 ± 0.59). This result highlights an increasing role of nitrate in particulate matter pollution in recent years in Beijing. Aerosol composition and size distributions also changed significantly. Secondary inorganic species showed elevated contributions by ~10% in winter 2016 associated with corresponding decreases in organic aerosol (OA). Positive matrix factorization of OA illustrated the significant changes in both primary emissions and secondary production. While cooking OA decreased substantially from 25% in 2014 to 15% in 2016, the contribution of biomass burning OA slightly increased instead. Although secondary OA contributed similarly to OA in the two winters (49% vs. 53%), we observed ubiquitous increases (~50%) in photochemically related oxygenated OA and oxidized primary OA, and oxygen‐to‐carbon ratios of OA, indicating the enhanced photochemical production in winter 201...