Distribution of potentially toxic elements in sediment of the Anning River near the REE and V-Ti magnetite mines in the Panxi Rift, SW China

Abstract

To clarify the impact of developing world-class REE and V-Ti magnetite mines on the distribution of potentially toxic elements (As, Cd, Co, Cu, Cr, Hg, Ni, Pb, Tl, U, and Zn) in adjacent aqueous sediments, thirty sediment samples from the Anning River and seventeen ore samples from the Panxi Rift of China were investigated. The results from this study suggest the following: (1) Mining activities have resulted in severe pollution of sediment by potentially toxic elements, especially Pb with an average concentration of 213.8mg/kg, which is much higher than the probable effect concentration (PEC) and background values. (2) Different kinds of mines caused the enrichment of different elements in surface sediments. Heavy to extreme enrichment of Pb (EF=45) and U (EF=12) was observed in sediment near the Mianning REE mine, and severe enrichment of Pb (EF=54), As (EF=18), Cd (EF=13) and U (EF=8) was observed in sediment near the Lugu iron mine. (3) Concentrations of Pb and As in sediment that were extremely higher than the PEC indicate probable toxicity and support the need for further speciation analysis. (4) The joint application of distribution characteristics analysis (DCA) and robust regression (RR) was useful in identifying the source of potentially toxic elements in sediment near mining areas. Distribution characteristics analysis of risk elements can qualitatively suggest outliers, and robust regression can quantitatively identify whether a high concentration of a risk element can be classified as an outlier compared to a reference element.