Diurnal Variations and Source Apportionment of Water-soluble Ions in PM2.5 During Winter in Nanjing Jiangbei New Area
【Abstract】To gain a better understanding of the day-night variation characteristics of water-soluble ions, PM2.5 samples were continuously collected for two months in the Nanjing Jiangbei New Area during winter. The diurnal variation and sources of watersoluble ions were studied. Results showed that the mass concentration of water-soluble ions ranged from 17.07 μg·m−3 to 168.43μg·m−3 with a mean value of (59.01 ± 30.75) μg·m−3. The average mass concentration of water-soluble ions in daytime was higher than that in the nighttime. The concentration ratio of NO3− and NH4+ to total ion concentrations was higher at night, while SO42− and Cl− were higher during daytime. SO42−, NO3−, and NH4+ (SNA) were the dominant species of water-soluble ions in PM2.5 in Nanjing. The mass concentration of SNA on polluted days was higher than that on clean days. The ratio of the anion-cation balance ( AE/CE) was larger than 1, indicating that the PM2.5 was acidic. There was a significant linear correlation between NH4+ with NO3− and SO42−, indicating that it occurred mainly in the form of NH4NO3 and (NH4)2SO4 in PM2.5. The PMF source apportionment indicated that water-soluble ions of PM2.5 were mainly derived from motor vehicle emissions, fossil fuel combustion, biomass burning, and dust in the Nanjing Jiangbei New Area.
【Keywords】 Nanjing; PM2.5; water-soluble ions; day-night characteristics; source analysis;
 Steinfeld J H, Pandis S N. Atmospheric chemistry and physics: from air pollution to climate change [J]. Environment: Science and Policy for Sustainable Development, 1998, 40(7): 26.
 Ramanathan V, Carmichael G. Global and regional climate changes due to black carbon [J]. Nature Geoscience, 2008, 1(4): 221–227.
 Cao R F, Yan Y L, Guo L L, et al. Distribution characteristics of water-soluble ions in size-segregated particulate matters in Taiyuan [J]. Environmental Science, 2016, 37(6): 2034–2040 (in Chinese).
 Wang S M, Li Q Y, Li K, et al. Preliminary study on pollution characteristics of ambient ultrafine particles during heating period [J]. Journal of Environment and Health, 2017, 34(12): 1039–1043 (in Chinese).
 Dao X, Zhang L L, Wang C, et al. Characteristics of mass and ionic compounds of atmospheric particles in winter and summer of Beijing-Tianjin-Hebei area, China [J]. Environmental Chemistry, 2015, 34(1): 60–69 (in Chinese).
 Wang H L, Zhu B, Shen L J, et al. Water-soluble ions in atmospheric aerosols measured in five sites in the Yangtze River Delta, China: size-fractionated, seasonal variations and sources [J]. Atmospheric Environment, 2015, 123: 370–379.
 Hu G Y, Zhang Y M, Sun J Y, et al. Variability, formation and acidity of water-soluble ions in PM2.5 in Beijing based on the semi-continuous observations [J]. Atmospheric Research, 2014, 145–146: 1–11.
 Xu C, Ye H, Shen J D, et al. Light scattering extinction properties of atmospheric particle and pollution characteristics in hazy weather in Hangzhou [J]. Environmental Science, 2014, 35(12): 4422–4430 (in Chinese).
 Booth B B B, Dunstone N J, Halloran P R, et al. Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability [J]. Nature, 2012, 484(7393): 228–232.
 Wang X Q, Zhou Y, Cheng S Y, et al. Characterization and regional transmission impact of water-soluble ions in PM2.5 during winter in typical cities [J]. China Environmental Science, 2016, 36(8): 2289–2296 (in Chinese).
 Li M. Chemical composition, seasonal variation and sources of water-soluble organic components in PM2.5 in Shanghai [D]. Shanghai: Shanghai University, 2013 (in Chinese).
 Kang C M, Lee H S, Kang B W, et al. Chemical characteristics of acidic gas pollutants and PM2.5 species during hazy episodes in Seoul, South Korea [J]. Atmospheric Environment, 2004, 38(28): 4749–4760.
 Liu J, Wu D, Fan S, et al. A one-year, on-line, multi-site observational study on water-soluble inorganic ions in PM2.5, over the Pearl River Delta region, China [J]. Science of the Total Environment, 2017, 601–602: 1720–1732.
 Wang N F, Chen Y, Hao Q J, et al. Seasonal variation and source analysis of the water-soluble inorganic ions in fine particulate matter in Suzhou [J]. Environmental Science, 2016, 37(12): 4482–4489 (in Chinese).
 Yin L, Dong M L, Ren R R, et al. Characteristics of PM2.5 and water-soluble ions in ambient air in Zhoushan [J]. Environmental Chemistry, 2019, 38(3): 556–564 (in Chinese).
 Sun Y C, Jiang N, Wang B S, et al. Seasonal characteristics and source analysis of water-soluble ions in PM2.5 of Anyang City [J]. Environmental Science, 2020, 41(1): 75–81 (in Chinese).
 Zhang Z W, Hu G R, Yu R L, et al. Characteristics and sources apportionment of water-soluble ions in PM2.5 of Xiamen City, China [J]. China Environmental Science, 2016, 36(7): 1947–1954 (in Chinese).
 Guang W, Li L J, Xiang R B. PM2.5 and its ionic components at a roadside site in Wuhan, China [J]. Atmospheric Pollution Research, 2019, 10(1): 162–167.
 Zhao L, Wang L T, Tan J H, et al. Changes of chemical composition and source apportionment of PM2.5 during 2013–2017 in urban Handan, China [J]. Atmospheric Environment, 2019, 206: 119–131.
 Wang H B, Shooter D. Coarse-fine and day-night differences of water-soluble ions in atmospheric aerosols collected in Christchurch and Auckland, New Zealand [J]. Atmospheric Environment, 2002, 36(21): 3519–3529.
 Liu J S, Gu Y, Ma S S, et al. Day-night differences and source apportionment of inorganic components of PM2.5 during summer winter in Changzhou City [J]. Environmental Science, 2018, 39(3): 980–989 (in Chinese).
 Liu G R, Peng X, Wang R K, et al. A new receptor model incremental lifetime cancer risk method to quantify the carcinogenic risks associated with sources of particle-bound polycyclic aromatic hydrocarbons from Chengdu in China [J]. Journal of Hazardous Materials, 2015, 283: 462–468.
 Gu J X, Wu L P, Huo G Y, et al. Pollution character and source of water-soluble inorganic ions in PM2.5 over Tianjin [J]. Environmental Monitoring in China, 2013, 29(3): 30–34 (in Chinese).
 Chen J Y, Tang K J, Zhu Y, et al. Pollution characteristics of water-soluble ions in PM2.5 of Hangzhou [J]. Journal of Zhejiang University of Technology, 2016, 44(4): 410–416 (in Chinese).
 Liu Y S, Li X R, Zhang Y M, et al. Characteristics and sources of airborne fine particles during the fall and winter in Ji’nan [J]. Environmental Chemistry, 2017, 36(4): 787–798 (in Chinese).
 Du Q Q, Wu L P, Zhao X Y, et al. Characteristics and sources analysis of water-soluble ions of ambient air PM2 5 in winter in Linyi City [J]. Research of Environmental Science, 2019, 32(8): 1348–1357 (in Chinese).
 Ianniello A, Spataro F, Esposito G, et al. Chemical characteristics of inorganic ammonium salts in PM2.5 in the atmosphere of Beijing (China) [J]. Atmospheric Chemistry and Physics, 2011, 11(21): 10803–10822.
 GB 3095-2012,环境空气质量标准 [S]. (in Chinese).
 Zhang J Q, Wang S L, Luo D T, et al. Characterization and source analysis of PM2.5 and water-soluble ions during winter in Liao Cheng City [J]. Research of Environmental Sciences, 2018, 31(10): 1712–1718 (in Chinese).
 Zhang C, Yu X N, An J L, et al. Aerosol chemical characteristics for different air pollution levels in North Suburban Nanjing [J]. Environmental Science, 2017, 38(12): 4932–4942 (in Chinese).
 Shen Z X, Li L Z, Du N, et al. Mass concentration and watersoluble ions in spring aerosol (PM2.5) at Xi’an [J]. Ecology and Environment, 2007, 16(4): 1193–1198 (in Chinese).
 Sun R, Zhang W J, Dong H Y, et al. Chemical character and source analysis of water-soluble irons in PM10 and PM2.5 in Tianjin City [J]. Environmental Monitoring in China, 2014, 30(2): 145–150 (in Chinese).
 Fan M Y, Cao F, Zhang Y Y, et al. Characteristics and sources of water soluble inorganic ions in fine particulate matter during winter in Xuzhou [J]. Environmental Science, 2017, 38(11): 4478–4485 (in Chinese).
 Chen J M, Li C L, Ristovski Z, et al. A review of biomass burning: emissions and impacts on air quality, health and climate in China [J]. Science of the Total Environment, 2017, 579: 1000–1034.
 Andreae M. Soot carbon and excess fine potassium: long-range transport of combustion-derived aerosols [J]. Science, 1983, 220(4602): 1148–1151.
 Zhang K, Wang Y S, Wen T X, et al. Water-soluble chloride in aerosol PM10 in Beijing [J]. Environmental Science, 2006, 27(5): 825–830 (in Chinese).
 Dai Y L, Tao J, Lin Z J, et al. Characteristics of haze and its impact factors in four megacities in China during 2006–2009 [J]. Environmental Science, 2013, 34(8): 2925–2932 (in Chinese).
 Pathak R K, Wu W S, Wang T. Summertime PM2.5 ionic species in four major cities of China: nitrate formation in an ammoniadeficient atmosphere [J]. Atmospheric Chemistry and Physics, 2009, 9(5): 1711–1722.
 Bozzetti C, El Haddad I, Salameh D, et al. Organic aerosol source apportionment by offline-AMS over a full year in Marseille [J]. Atmospheric Chemistry and Physics, 2017, 17(13): 8247–8268.
 Zhao P S, Dong F, He D, et al. Characteristics of concentrations and chemical compositions for PM2.5 in the region of Beijing, Tianjin, and Hebei, China [J]. Atmospheric Chemistry and Physics, 2013, 13(9): 4631–4644.
 Jiang H M, Xiao H, Song H, et al. Characteristics of watersoluble inorganic ions in PM2.5 during a winter haze episode in Wuhan city [J]. Journal of Nanjing University of Information Science and Technology (Natural Science Edition), 2018, 10(5): 590–598 (in Chinese).
 Li C L, Wang J Y, Miao X H, et al. Characteristics of carbon and water-soluble Ions of PM2.5 in Winter of Xuzhou City [J]. Environmental Science and Technology, 2018, 31(2): 23–28 (in Chinese).
 Li Y H. Chemical characteristics and source apportionment of atmospheric fine particles in Lanzhou city [D]. Lanzhou: Lanzhou University, 2015 (in Chinese).