Journal of Marine Science: Research & Development
Open Access

Abstract

Information on chemical partitioning of airborne metals, particularly during haze–fog episodes, is limited. Fine particulate matter (PM2.5) was collected during a severe haze–fog event in winter and non–haze fog periods in summer and fall from a typical Chinese mega-city, Nanjing. The particulate-bound metals (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Sr, Ti, V, and Zn) were chemically fractionated by using a four–step sequential extraction procedure and human health risk was assessed. During the haze–fog episode, PM2.5 was extremely elevated with a mean concentration of 281 μg/m3, whereas the mean PM2.5 concentrations in summer and fall periods were 86 μg/m3 and 77 μg/m3, respectively. All elements showed obviously higher concentrations and many metals exceeded the relevant limits on haze–fog days. K, Na, Sr, Zn, Mo, Ca, Cd, Mg, Mn, Cu, Ba, Cr and As all showed relatively high proportions of the soluble and exchangeable fraction and strong bio-accessible potential. High temperatures and humidity may increase the bio–accessible fraction of many particulate-bound metals. The hazard index for potential toxic metals was 0.115 and lower than the safe limit (1). However, the combined carcinogenic risk was 1.32×10−6 for children and 5.29×10−6 for adults, with both values being higher than the precautionary criterion (10−6). Results of this study can provide information for the geographical behavior and risk mitigation of airborne metals.

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