Abstract:

 Seventeen atmospheric dustfall samples were collected successively from December 2006 to December 2007 in Nanjing, China. All dustfall samples were analyzed for concentrations of As, Cd, Cr, Cu,  Hg, Mn, Mo, Ni, Pb, Se and Zn. The results indicated that, compared with the background values of soil in Nanjing area, atmospheric dustfalls have elevated metal concentrations as a whole, except those of Cr, Fe and Mn. Correlation coefficient analysis and principal component analysis (PCA) were performed and three main sources were identified: (1)As, Cu, Pb, Hg and Se are mainly derived from coal combustion and traffic exhaust; (2)Cd, Ni, Mo and Zn are possibly related to petrochemicals, and Mo is also originated from industrial sources and soil particles (natural source). The samples near to the petrochemical park have relatively high concentrations in these elements, which further confirms the source identification; (3)Cr and Mn are mainly derived from soil particles. Based on concentration analysis and correlation analysis, Fe was selected as the reference element to calculate the heavy metal enrichment factors (EFs), which in turn further validates the source identification. Naturally derived Cr and Mn show the lowest enrichment relative to the background values. Nevertheless, anthropogenically enhanced Cd, Pb, Se and Zn show maximum enrichments. Therefore, EFs give an insight of the level of human influence on atmospheric dustfalls.

Key words:

Key words: heavy metals; enrichment factors; principal component analysis; Nanjing