title: Highly time-resolved characterization of water-soluble inorganic ions in PM2.5in a humid and acidic mega city in Sichuan Basin, China.
abstract: To investigate the characteristics of water-soluble inorganic ions (WSIIs) in Chongqing, a well-known foggy and acid region in southwestern China, hourly real-time concentrations of five cations (Na+, K+, NH4+, Ca2+, and Mg2+) and six anions (F-, Cl-, NO2-, NO3-, PO43-, and SO42-) in PM2.5during winter (from Dec. 18, 2015 to Mar. 20, 2016) in Chongqing were collected by applying In-situ Gas and Aerosol Compositions Monitor. The hourly total concentration of WSIIs was 38.5μg/m3on average, accounting for 57% of PM2.5mass concentration. Secondary inorganic aerosols (NH4+, NO3-, and SO42-) were dominant WSIIs, accounting for 91% of WSIIs mass. Compared to ten years ago, SO42-concentrations were decreased by 31% but NO3-levels were doubled, likely indicative of sharply enhanced contribution to fine particle pollution from mobile sources over stationary sources. NO3-originated from the current fluxes of NH3and HNO3onto sulfate particles and/or from in-cloud processes were critical pathways under humid conditions in the study area. Water content and/or RH might be important factors controlling nitrate formation. Trajectory analysis manifested that aerosol pollutions in Chongqing were mostly caused by local emissions.
authors.affiliation: Research Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China.
authors.forename: Mi
authors.initials: M
authors.lastname: Tian
authors.affiliation: Research Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China. Electronic address: hbwang@cigit.ac.cn.
authors.forename: HuanBo
authors.initials: H
authors.lastname: Wang
authors.affiliation: Research Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Air Quality Research Division, Science Technology Branch, Environment and Climate Change Canada, Toronto M3H 5T4, Canada.
authors.forename: LeiMing
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Research Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China.
authors.forename: GuangMing
authors.initials: G
authors.lastname: Shi
authors.affiliation: Research Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Chongqing Environmental Monitoring Center, Chongqing 401147, China.
authors.forename: JiaYan
authors.initials: J
authors.lastname: Yu
authors.affiliation: Chongqing Environmental Monitoring Center, Chongqing 401147, China.
authors.forename: ChongZhi
authors.initials: C
authors.lastname: Zhai
authors.affiliation: Chongqing Environmental Monitoring Center, Chongqing 401147, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Research Center for Atmospheric Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Yangtze Normal University, Chongqing 408100, China. Electronic address: fmyang@cigit.ac.cn.
authors.forename: FuMo
authors.initials: F
authors.lastname: Yang
keywords: Formation mechanism; High time resolution; Particle acidity; Water-soluble ions