Assessment of heavy metal pollution in sediments from Xiangjiang River (China) using sequential extraction and lead isotope analysis

The heavy metal (such as Cr, Ni, Cu, Cd, Pb, and Zn) concentration, speciation, and pollution source in 43 sediment samples from the Xiangjiang River were investigated using sequential extraction combined with Pb isotope analysis. Cu, Cd, Pb, and Zn concentrations are higher than their background values, while Cr and Ni concentrations are close to those. Sequential extraction demonstrates that heavy metals have different fractions, showing different bioavailabilities. The w(Pb-206)/w(Pb-207) ratio increases with decreasing bioavailability in the order of exchangeable < carbonatea parts per thousand Fe-Mn oxidesa parts per thousand organic < residual (p < 0.05). Wastewater, dust, and slag from mining and smelting areas, and the residual Pb are assumed to be the primary anthropogenic and natural sources of Pb, respectively. The percentages of anthropogenic Pb in the exchangeable, carbonate, Fe-Mn oxides, and organic fractions are (91.5 +/- 16.7)%, (61.1 +/- 13.9)%, (57.4 +/- 11.1)%, and (55.5 +/- 11.2)%, respectively, suggesting a significant input of anthropogenic Pb in these four fractions.