Estimation of the PM_(2.5) effective hygroscopic parameter and water content based on particle chemical composition: Methodology and case study

作     者：LIU YueChen WU ZhiJun TAN TianYi WANG YuJue QIN YanHong ZHENG Jing LI MengRen HU Min 

作者机构：Department of Environmental Science Peking University 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2016年第59卷第8期

页      面：1683-1691页

核心收录：

学科分类：07[理学] 070602[理学-大气物理学与大气环境] 0706[理学-大气科学] 

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 41475127, 91544214) the National Basic Research Program of China (Grant No. 2013CB228503) the Strategic Priority Research Program of the China Academy of Sciences (Grant No. XDB05010500) the Special Fund of State Key Joint Laboratory of Environment Simulation and Pollution Control (Grant No. 14L02ESPC) the nonprofit research projects of Ministry of Environmental Protection, the People’s Republic of China (Grant No. 201409010) the Collaborative Innovation Center for Regional Environmental Quality 

主　　题：PM2.5 Effective hygroscopic parameter Water content Chemical component Relative humidity 

摘      要：Particle hygroscopicity plays a key role in understanding the mechanisms of haze formation and particle optical properties. The present study developed a method for predicting the effective hygroscopic parameter k and the water content of PM_(2.5) on the basis of the k-K?hler theory and bulk chemical components of PM_(2.5). Our study demonstrated that the effective hygroscopic parameter can be estimated using the PM_(2.5) mass concentration, water-soluble ions, and total water-soluble carbon. By combining the estimated k and ambient relative humidity, the water content of PM_(2.5) can be further estimated. As an example, the k and water content of PM_(2.5) in Beijing were estimated utilizing the method proposed in this study. The annual average value of k of PM_(2.5) in Beijing was 0.25±0.09, the maximum k value 0.26±0.08 appeared in summer, and the seasonal variation is insignificant. The PM_(2.5) water content was determined by both the PM_(2.5) hygroscopicity and the ambient relative humidity(RH). The annual average mass ratio of water content and PM_(2.5) was 0.18±0.20, and the maximum value 0.31±0.25 appeared in summer. Based on the estimated water content of PM_(2.5) in Beijing, the relationship between the PM_(2.5) water content and RH was parameterized as: m(%)=0.03+(5.73×10^(-8)) ×RH^(3.72).This parametric formula helps to characterize the relationship between the PM_(2.5) mass concentration and atmospheric visibility.