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| Investigation of chemical compositions of atmospheric fine particles during a wintertime haze episode in Taiyuan City |
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Abstract The aim of this study is to investigate the mass concentration and chemical compositions of atmospheric fine particulate matter (PM2.5) at different stage during a typical urban haze episode in Taiyuan, Shanxi Province, China. The PM2.5 samples were collected every four hours at a five-story building in Shanxi University using a medium-volume PM2.5 impactor at a flow rate of 100L/min from 4p.m. on Dec. 27, 2011 to 4a.m. on Jan. 3, 2012 when a typical haze event occurred. Overall 39 samples were obtained at different haze stages, namely infancy, development, peak, decay, and disappearance. The mass concentrations of ambient PM2.5 were measured and the heavy metals, water-soluble ions, and organic carbon (OC) and elemental carbon (EC) in all samples were detected, respectively. Results showed that during the haze event, the mean concentration of ambient PM2.5 was (692±272)μg/m3 (about 12.8 times higher than that when haze disappeared) and the levels of OC, Hg, As, Pb, NH4+, SO42－, NO3－, Cl－, F－, and K+ were significantly elevated while the levels of Zn, Ca2+, and Mg2+ were increased slightly. It indicated that secondary aerosols and organic matter had been formed abundantly and suggested that coal and biomass combustion contributed more to the haze formation than traffic vehicles, soil, and construction dust. It was concluded that coal and biomass burning in winter in Taiyuan was the main factor responsible for the elevation of atmospheric PM2.5 concentration and made more influences on modification of PM2.5 in compositions when haze occurred.
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Received: 24 July 2013
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