| Dongguan is one of the most economically developed cities in southern China. It has a population of8.22million and2,465square kilometers. The growing number of automotive and industrial development has resulted in serious pollution. So it is very urgent to study the source and composition of PM2.5in Dongguan urban area.This paper studied metals, water-soluble ions, concentration and seasonal variation of PM2.5of PM2.5in Dongguan urban area and discussed the possible sources of pollution. The results showed that:(1) PM2.5at nighttime (99.68μg/m3) was1.21times that of the daytime (83μg/m3), and the average PM2.5concentration of haze-day (103.6μg/m3) was1.41times that of non-haze day (73.6μg/m3). The atmospheric concentrations of particulate matter PM2.5at nighttime was8μg/m3higher than at daytime in Dongguan, and both are1.07,1.25times of the national ambient air quality standards. PM2.5in the haze and non-haze day showed the same trend. The average PM2.5concentration in haze day was about120μg/m3, while87μg/m3in non-haze day.(2) Major elements and metals concentrations (Al, Fe, Mg, Mn, Cd, Co, C, Ni, Pb, V and Zn) in PM2.5were higher in Dongguan. The order of metal concentration was:Al> Mg> Fe> Ca> K> Mn> Sr> B> Ba> Ag>V> Pb> Cs> Cr> Cu> Cd> Cr> Co> Ni> Hg> Tl> Cs> Be. According to the results of20kinds of metals detected, the mass concentration of14kinds of metals at night was higher than at daytime. The average concentrations of Pb, Cd, Ag, V at night was1.66,1.42,1.23,1.08,1.10times than at daytime, respectively.(3)The total concentration of water-soluble inorganic ions in PM2.5was25.75-79.9μg/m3, and accounted for22%-34%of the PM2.5mass concentration, among which the SO42-accounted for10.56%. |
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