Journal of Marine Science: Research & Development
Open Access

Abstract

Information on chemical partitioning of airborne metals, particularly during hazeâ��fog episodes, is limited. Fine particulate matter (PM2.5) was collected during a severe hazeâ��fog event in winter and nonâ��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 fourâ��step sequential extraction procedure and human health risk was assessed. During the hazeâ��fog episode, PM2.5 was extremely elevated with a mean concentration of 281 �¼g/m3, whereas the mean PM2.5 concentrations in summer and fall periods were 86 �¼g/m3 and 77 �¼g/m3, respectively. All elements showed obviously higher concentrations and many metals exceeded the relevant limits on hazeâ��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 bioâ��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��10â��6 for children and 5.29��10â��6 for adults, with both values being higher than the precautionary criterion (10â��6). Results of this study can provide information for the geographical behavior and risk mitigation of airborne metals.

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