Evaluation and Sources of Heavy Metal Pollution in the Surface Soil of the Qaidam Basin

To understand surface soil heavy metal pollution characteristics, and the spatial distribution and sources of pollution in the main sedimentary features of the Qaidam Basin, a total of 129 topsoil samples(0-10 cm) were collected within a 25 km radius. The concentrations of As, Ba, Cr, Mn, Nb, Ni, Pb, Ti, Zn, Zr, and ten kinds of heavy metals were determined, the degree of contamination and potential sources quantitatively analyzed based on enrichment factors(EFs), the ground accumulation index(Igeo), and the absolute principal component-multiple linear regression(APCS-MLR) receptor model. The results showed that the surface soils of the Qaidam Basin have experienced pollution from ten kinds of heavy metals since the 1960s, with varying degrees of enrichment. As and Pb represent probable point source pollutants, and the basin as a whole shows negligible to low levels of pollution. The APCS-MLR analysis showed that heavy metal pollution derives from two sources, natural factors and anthropogenic(transportation) sources. Specifically, As, Cr, Mn, Nb, Ni, Ti, Zn, and Zr are associated with natural sources, while Ba and Pb are associated with both natural and anthropogenic sources.