Spatial and seasonal variability of water-soluble ions in PM 2.5 aerosols in 14 major cities in China Miao-Ching Cheng a, 1 , Chen-Feng You a, b, * , Junji Cao c , Zhangdong Jin c a Department of Earth Sciences, National Cheng Kung University, Tainan 701, Taiwan b Earth Dynamic System Research Center, National Cheng Kung University, Taiwan c State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China highlights < 110 PM 2.5 samples in 14 major cities over China and analyze for WS ions in summer and in winter 2003. < Anthropogenic activities are the main sources for WS ions in PM 2.5 particles. < High concentrations of WS-Zn, Pb and S in winter are mainly due to coal burning. < Location of industrial zones influence heavy metals of aerosols significantly. article info Article history: Received 31 January 2012 Received in revised form 11 June 2012 Accepted 13 June 2012 Keywords: Acid precipitation PM 2.5 Water-soluble ions Anthropogenic sources Industrial zones abstract We analyzed PM 2.5 aerosols from 14 major cities in China for concentrations of water-soluble (WS) major and trace elements (Na, Mg, Ca, K, Fe, Mn, Zn, Rb, Sr, Ba, Pb, S and Cl). The main focus was to examine patterns in spatial distribution and seasonal variability. Using principal component analysis, we identi- fied three general sources for WS-elements in aerosols as anthropogenic, seasalts and fine dust particles originating from soils. The spatial patterns identified show that anthropogenic activity is the most important factor influencing the concentration of heavy metals in aerosols. Concentrations of WS-S, Zn and Pb were correlated with the locations of major industrial zones, and regulated by topography and seasonal weather patterns. We found higher WS-metals concentrations during the winter season, probably related to coal combustion in northern China. Moderate correlations of WS-S, Zn, Pb and Cl suggest that coal combustion releases. The seasonal pattern in WS-Fe concentrations shows the importance of acid precipitation events where coal combustion contributes to additional Fe (II) depo- sition. The findings of this study support the argument that WS-S in fine particles enhanced the production of hydrogen ions act to reduce the pH values of precipitation. Our interpretation of these spatial and seasonal patterns in WS-major and trace elements in aerosols highlights the need for continued research on trends in acidic deposition in major industrial cities in China. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction PM 2.5 aerosols derived mainly from the combustion of fossil fuels, traffic, and smelting and metal processing (Mouli et al., 2005; Tie and Cao, 2009). Atmospheric transport delivers pollutants from industrial and other anthropogenic activities in Asia to the western Pacific and other surrounding areas (Zhou et al., 1990; Uematsu et al., 1992). For example, large quantities of suspended particu- late matter (PM) and crustal materials are carried from desert regions in China (Arimoto et al., 2004; Zhang et al., 2011) and various components are mixed by seasonal winds to cause distinct variations in chemical compositions (Lee et al., 2009; Han et al., 2009). Increased industrial development has increased the anthropo- genic contribution from various sources to aerosol loadings around the world (Safai et al., 2010). Some of the concern is focused on Pb and Zn which are toxic metals largely associated with fine particles such as PM 2.5 (Schlesinger, 2007). These and other trace metals are mainly derived from industrial combustion at high temperature or transportation-derived emissions (Al-Momani, 2003; Garcia et al., 2006; Heal et al., 2005; Mihajlidi-Zeli c et al., 2006). * Corresponding author. Department of Earth Sciences, National Cheng Kung University, Tainan 701, Taiwan. E-mail address: cfy20@mail.ncku.edu.tw (C.-F. You). 1 Present address: Nan-Kwang Senior High School, No. 62, Zhongxing Rd., Xinying Dist., Tainan 730, Taiwan. Contents lists available at SciVerse ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv 1352-2310/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.atmosenv.2012.06.037 Atmospheric Environment 60 (2012) 182e192