Chemical characteristics of PM 10 during the summer in the mega-city Guangzhou, China Tingting Han a , Xingang Liu a, ⁎, Yuanhang Zhang b, ⁎, Jianwei Gu c , Hezhong Tian a , Limin Zeng b , Shih-Yu Chang d , Yafang Cheng e , Keding Lu b , Min Hu b a State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China b State Key Joint Laboratory of Environment Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China c Environmental Science Center, University of Augsburg, Augsburg 86159, Germany d Department of Public Health, Chung Shan Medical University, Taichung, Taiwan e Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany article info abstract Article history: Received 12 March 2013 Received in revised form 6 October 2013 Accepted 7 October 2013 With rapid economic development and the acceleration of urbanization, air pollution has become a serious problem in the mega-city Guangzhou, China. A field campaign to sample and analyze particulate matter (PM) chemical components was performed from July 6, 2006 to July 26, 2006, in Guangzhou. During the campaign, the average mass concentration of PM 10 was 89.0 ± 46.6 μgm -3 (the error represents one standard deviation). The PM 10 , sulfate, nitrate, ammonium, organic carbon (OC), and elemental carbon (EC) mass frequency distributions were analyzed. The [NO 3 - ]/[SO 4 2- ] mass ratio varied from 0.1 to 0.3, with an average of 0.2. A Pearson correlation analysis between [SO 4 2- ] and [NH 4 + ] and between [NO 3 - ] and [Na + ] showed that SO 4 2- existed as (NH 4 ) 2 SO 4 and NO 3 - existed as NH 4 NO 3 and NaNO 3 . Sulfate, nitrate, ammonium, EC and POM (particulate organic matter) accounted for 24.4%, 4.9%, 5.7%, 5.7% and 21.0%, respectively, of the PM 10 mass concentration during clean days and 25.7%, 3.9%, 7.9%, 5.4% and 20.8%, respectively, on hazy days. Among these species, SNA (sulfate, nitrate, and ammonium) were the most abundant, accounting for 35.0% and 37.5% of the PM 10 during clean and hazy days, respectively. The sum of POM and EC accounted for 26.7% and 26.2% of PM 10 in Guangzhou during clean and hazy days, respectively. There was no apparent difference in the chemical composition of PM 10 between clean and haze days. © 2013 Elsevier B.V. All rights reserved. Keywords: Particulate matter Water-soluble inorganic ions Organic carbon Elemental carbon Guangzhou 1. Introduction Air pollution, especially PM pollution, has attracted worldwide attention in recent years because of its impacts on visibility (Chen and Xie, 2012), human health (Xiao et al., 2006; Pope et al., 2009; Bell et al., 2011) and climate change (Das and Jayaraman, 2012; Wang, 2013). With economic development and the acceleration of urbanization, air pollution has become a serious problem in mega-cities in China. Air pollution in Chinese mega-cities has been shown to exhibit the following characteristics (Liu et al., 2013): (1) air pollution has changed from ‘coal smoke pollution’ to ‘complex atmospheric pollution’, i.e., air pollution was previously primarily produced from coal combustion and is now a combination of coal combustion and motor vehicle emissions; (2) the regional air pollution frequency of occurrence has been increasing, and the spatial extent has been expanding. Haze event (i.e., visibility less than 10 km and relative humidity less than 90%) (Wu et al., 2005), an extreme condition of air pollution, has been characterized by increasing frequencies, longer duration and expanding spatial extent (Wu et al., 2005; Zhang et al., 2008; Wang et al., 2006a); and (3) the particulate matter (PM) pollution level and the secondary pollutant mass fractions (e.g., sulfate, nitrate, ammonium, and secondary organic aerosols) in PM have been increasing. Atmospheric Research 137 (2014) 25–34 ⁎ Corresponding authors. E-mail addresses: liuxingang@bnu.edu.cn (X. Liu), yhzhang@pku.edu.cn (Y. Zhang). 0169-8095/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.atmosres.2013.10.004 Contents lists available at ScienceDirect Atmospheric Research journal homepage: www.elsevier.com/locate/atmos