Determining environmental risk and source of heavy metal(loid)s in the surrounding farmland soil of a zinc smelter in water source area, Northwest China

To explore the impact of metal smelting activities on surrounding environment in the water source area of the Mid-route of South-to-North Water Transfer Project of China, soil samples of farmland around a zinc smelter in this area were collected and the pollution, risk, and source of heavy metal(loid)s (As, Cu, Cr, Pb, Mn, Ni, V, and Zn) in soil samples were determined in this study. The heavy metal(loid)s contents were measured by X-ray fluorescence spectrometry and their pollution levels and ecological risks were assessed by geoaccumulation index, Nemerow synthetic pollution index,and potential ecological risk index. The possible sources of the heavy metals(loid)s were identified by multivariate statistical analysis methods. The results show that the mean contents of all analyzed heavy metal(loid)s in the farmland soil were above the local soil background values except Mn; the contents of As, Cu, Pb, Zn, and Ni in the downwind direction soil decreased with the distance increasing between the sampling site and the zinc smelter; the investigated soils were moderately to seriously polluted by heavy metal(loid)s and the heavy metal(loid)s presented moderately ecological risk as a whole; As, Cu, Pb, and Zn mainly originated from zinc-smelting activities; Cr, Mn, and V primarily derived from natural source; Ni mainly came from zinc-smelting activities, partly from natural source. The zinc-smelting activity influenced the heavy metal(loid)s content, particularly Zn and Pb, in the surrounding farmland soil. The local government should strengthen the cooperative monitoring of heavy metal(loid)s in farmland and agricultural products, as well as pollutant emission monitoring and control.