title: PM2.5in the Yangtze River Delta, China: Chemical compositions, seasonal variations, and regional pollution events.
abstract: Fine particle (PM2.5) samples were collected simultaneously at three urban sites (Shanghai, Nanjing, and Hangzhou) and one rural site near Ningbo in the Yangtze River Delta (YRD) region, China, on a weekly basis from September 2013 to August 2014. In addition, high-frequency daily sampling was conducted in Shanghai and Nanjing for one month during each season. Severe regional PM2.5pollution episodes were frequently observed in the YRD, with annual mean concentrations of 94.6 ± 55.9, 97.8 ± 40.5, 134 ± 54.3, and 94.0 ± 57.6 μg m-3in Shanghai, Nanjing, Hangzhou, and Ningbo, respectively. The concentrations of PM2.5and ambient trace metals at the four sites showed clear seasonal trends, with higher concentrations in winter and lower concentrations in summer. In Shanghai, similar seasonal patterns were found for organic carbon (OC), elemental carbon (EC), and water-soluble inorganic ions (K+, NH4+, Cl-, NO3-, and SO42-). Air mass backward trajectory and potential source contribution function (PSCF) analyses implied that areas of central and northern China contributed significantly to the concentration and chemical compositions of PM2.5in Shanghai during winter. Three heavy pollution events in Shanghai were observed during autumn and winter. The modelling results of the Nested Air Quality Prediction Modeling System (NAQPMS) showed the sources and transport of PM2.5in the YRD during the three pollution processes. The contribution of secondary species (SOC, NH4+, NO3-, and SO42-) in pollution event (PE) periods was much higher than in BPE (before pollution event) and APE (after pollution event) periods, suggesting the importance of secondary aerosol formation during the three pollution events. Furthermore, the bioavailability of Cu, and Zn in the wintertime PM2.5samples from Shanghai was much higher during the pollution days than during the non-pollution days.
authors.affiliation: Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Lili
authors.initials: L
authors.lastname: Ming
authors.affiliation: Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Ling
authors.initials: L
authors.lastname: Jin
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.affiliation: LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Pingqing
authors.initials: P
authors.lastname: Fu
authors.affiliation: LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Wenyi
authors.initials: W
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
authors.forename: Di
authors.initials: D
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
authors.forename: Gan
authors.initials: G
authors.lastname: Zhang
authors.affiliation: LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Zifa
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. Electronic address: cexdli@polyu.edu.hk.
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Li
mesh_terms: D000336:Aerosols / Q000032:analysis; D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry; D002244:Carbon / Q000032:analysis; D002681:China; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis* / Q000737:chemistry*; D007477:Ions / Q000032:analysis; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis* / Q000737:chemistry*; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D014131:Trace Elements / Q000032:analysis; D001335:Vehicle Emissions / Q000032:analysis; D014867:Water / Q000737:chemistry
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D004785:Environmental Pollutants; D007477:Ions; D052638:Particulate Matter; D014131:Trace Elements; D001335:Vehicle Emissions; D014867:Water; D002244:Carbon
keywords: Bioavailability; Nested air quality prediction modeling system; Potential source contribution function; Primary organic carbon; Secondary aerosol