title: One year online measurements of water-soluble ions at the industrially polluted town of Nanjing, China: Sources, seasonal and diurnal variations.
abstract: Half-hourly mass concentrations water-soluble ions (WSIs) and PM2.5 were measured online a Rapid Collector of Fine Particles and Ion Chromatography system (RCFP-IC) and FH62C14 Continuous Particulate Monitor in Nanjing from October 18, 2013 to November 17, 2014. The WSIs concentration ranged from 7.07 to 333.42 μg m(-3) with an annual mean of 76.32 μg m(-3). The WSIs ranked in the order of SO4(2-) > NH4(+) > NO3(-) > Cl(-) > NO2(-) > K(+) > Ca(2+) > Na(+) > Mg(2+). The PM2.5 concentration ranged from 4.00 to 400 μg m(-3) with an annual mean of 83.58 μg m(-3). The concentrations of WSIs varied in the order of winter (115.77 μg m(-3)) > spring (76.10 μg m(-3)) > autumn (63.72 μg m(-3)) > summer (59.75 μg m(-3)), with the highest level in January (123.99 μg m(-3)) and lowest level in August (43.73 μg m(-3)). Different WSIs had distinct diurnal variations. The source analysis of the WSIs in the PCA/APCS mode illustrated that the sources consisted of secondary aerosol, coal combustion, mineral dust, biomass burning, traffic emissions and sea salt. In addition, there were seasonal variations amongst the various sources. The haze formation mechanism was different in summer and winter. The winter was dominated by NH4NO3 (18.56%), (NH4)2SO4 (28.63%), NH4(+) (11.27%), SO4(2-) (18.35%) and NO3(-) (13.13%), and by NH3 (25.93%), (NH4)2SO4 (13.37%), SO4(2-) (15.74%) and NO3(-) (9.97%) in summer. Consequently, the proportions of HCl, HNO3, NH4(+), SO4(2-) and NO3(-) were much larger during haze episodes in winter, while it was dominated by NH4NO3, NH4(+), (NH4)2SO4, SO4(2-) and NO3(-) during summer haze episodes.
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Honglei
authors.initials: H
authors.lastname: Wang
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China. Electronic address: junlinan@nuist.edu.cn.
authors.forename: Junlin
authors.initials: J
authors.lastname: An
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Mengtian
authors.initials: M
authors.lastname: Cheng
authors.affiliation: Jiaxing Environmental Monitoring Station, Jiaxing 314000, China.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Shen
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Yuesi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Duan
authors.affiliation: Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Sullivan
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Li
authors.initials: L
authors.lastname: Xia
mesh_terms: D000336:Aerosols; D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D002681:China; D003031:Coal; D004391:Dust; D004784:Environmental Monitoring; D007477:Ions / Q000032:analysis; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis* / Q000737:chemistry; D012621:Seasons; D012623:Seawater; D012995:Solubility; D001335:Vehicle Emissions; D014867:Water / Q000737:chemistry
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D003031:Coal; D004391:Dust; D007477:Ions; D052638:Particulate Matter; D001335:Vehicle Emissions; D014867:Water
keywords: Diurnal variation; Haze; PCA/APCS; RCFP-IC; Source; Water-soluble ions