中国西安市及び北京市における大気粉塵中水溶性イオン成分濃度の特徴

概要

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A yearlong field observation of water-soluble ionic composition in TSP and PM_<2.5> was carried out in Xi'an and Beijing, China from September 2005 to August 2006 with the aim of characterizing the atmosphere in Xi'an. Concentraions of water-soluble ions (Na^+, NH_4, K^+, Mg^<2+>, Ca^<2+>, F^-, Cl^-, NO_3^-, and SO_4^<2->) were determined by ion chromatography for approximately 250 samples. The concentrations of the sum of 9 ions were TSP: 81.8±64.8μg/m^3 (n=80), PM_<2.5> :46.0±31.7μg/m^3 (n=68) in Xi'an, and TSP: 60.8±27.2μg/m^3 (n=44), PM_<2.5> :33.6±20.1μg/m^3 (n=45) in Beijing. The concentration of each ion in Xi'an was 1-3 times higher than that in Beijing. SO_4^<2-> was the dominant ionic component of the aerosols in both cities. SO_4^<2-> concentrations in PM_<2.5> in both cities in summer was 1.3-1.9 times higher than those in winter while SO_2 concentrations in both cities in winter were 4-8 times higher than those in summer. These facts suggest that sulfate concentrations in both cities were not mainly controlled by SO_2 concentration but the intensity of gas- or liquid-phase reaction in the atmosphere.
2007-12-28