Aerosol Liquid Water Driven by Anthropogenic Inorganic Salts: Implying Its Key Role in Haze Formation over the North China Plain


Wu ZJ, Wang Y, Tan TY, Zhu YS, Li MR, Shang DJ, Wang HC, Lu KD, Guo S, Zeng LM, et al. Aerosol Liquid Water Driven by Anthropogenic Inorganic Salts: Implying Its Key Role in Haze Formation over the North China Plain. Environmental Science & Technology Letters. 2018;5:160-166.


This study reveals aerosol liquid water content (ALWC) in PM2.5 ranged from 2% up to 74%, and the associated secondary inorganic fraction rose from 24% to 55%, while ambient relative humidity (RH) increased from 15% to 83% in the atmosphere over Beijing. Unexpectedly, the secondary inorganic fraction in PM2.5 increased with an increase in the ambient RH, which is a meteorological parameter independent of anthropogenic activities, indicating the presence of a feedback mechanism driven by Henry's law and thermodynamic equilibrium. During haze episodes, simultaneously elevated RH levels and anthropogenic secondary inorganic mass concentrations resulted in an abundant ALWC. The condensed water could act as an efficient medium for multiphase reactions, thereby facilitating the transformation of reactive gaseous pollutants into particles and accelerating the formation of heavy haze. ALWC was well correlated with the mass concentrations of both nitrate and sulfate, indicating both nitrate and sulfate salts play key roles in determining ALWC. Coincident with a significant reduction in SO2 emissions throughout China, nitrates will become a dominant anthropogenic inorganic salt driving ALWC. Thus, the abundance of ALWC and its effects on the aerosol chemistry and climate should be reconsidered.


ISI Document Delivery No.: FZ5UGTimes Cited: 5Cited Reference Count: 60Wu, Zhijun Wang, Yu Tan, Tianyi Zhu, Yishu Li, Mengren Shang, Dongjie Wang, Haichao Lu, Keding Guo, Song Zeng, Limin Zhang, YuanhangZhang, Yuanhang/F-7038-2011; Zeng, Limin/D-3948-2013; Guo, Song/D-9218-2012; Lu, Keding/A-7282-2012Guo, Song/0000-0002-9661-2313; Lu, Keding/0000-0001-9425-9520; Wang, Haichao/0000-0001-6161-1874National Natural Science Foundation of China [41475127, 41571130021]; National Key R&D Program of China [2016YFC0202800]This work is supported by the following projects: National Natural Science Foundation of China (41475127, 41571130021) and National Key R&D Program of China (2016YFC0202800: Task 1). The authors greatly thank Min Hu, Yuxuan Bian, Ying Chen, and Hongyu Guo for useful discussions and also thank three anonymous reviewers for their hints and suggestions.53048Amer chemical socWashington