Characterization of PM2.5/PM2.5-10 and source tracking in the juncture belt between urban and rural areas of Beijing

Coarse (PM_2.5–10) and fine (PM_2.5) atmospheric particulate samples were collected in summer and winter during 2005–2007 in the juncture belt between urban and rural areas of Beijing. Elements, ions, organic/elemental carbon (OC/EC) and polynuclear aromatic hydrocarbons (PAHs) were determined to obtain some latest information about the particulate pollution in the juncture belt of Beijing. Particulate matter levels at this site were high as compared with the levels at other sampling sites in Beijing. Pollution elements, secondary ions and PAHs were enriched in fine particles rather than in coarse particles. An obvious seasonal variation of the chemical composition of PM was observed. Source apportionment results showed that secondary components were the largest mass contributor of PM_2.5, accounting for 28%; whereas soil-related sources were the largest contributor of PM_2.5–10, explaining about 49% of the total mass. The abnormal levels of soil heavy metals at the electronic waste disassembly site in the upwind villages suggested the potential impact of such activities to the environment. Supported by the Swedish International Development Agency (SIDA), National Science Fund for Distinguished Young Scholars (Grant No. 20725723), and State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (Grant No. KF2008-18)