Spatial Distribution, Risk Assessment, Source Apportionment and Stabilization Performance of Potentially Toxic Elements in Sediments of Dongdagou River, Northwest China

Ecological Protection and High-quality Development of the Yellow River Basin has been a major national strategy in China, and Dongdagou River, which is located in Baiyin city, Gansu province, northwest of China, is the largest potentially toxic elements input tributary in the upper reaches of the Yellow River. At present, it is urgent to conduct research on the pollution and remediation of potentially toxic elements in sediment from the Dongdagou River. Especially, few researchers have been studied the stabilization performance of potentially toxic elements in sediments of Dongdagou River. Potentially toxic elements from 459 sampling sites in sediments of Dongdagou River were studied. The results revealed that potentially toxic elements concentrations in ascending order were Hg < Cd < Cr < Ni <  < Cu < As < Pb < Zn, and the concentrations of almost all the potentially toxic element decreased with the increase of sediment depth. The pollution levels (PLI) of 56.99% sites were “moderately polluted” or higher, whereas the potential ecological risks (PERI) of 90.41% sites were “very high risk”, scattered irregularly along the whole length of the river. Besides, the pollution levels (I_geo) of potentially toxic elements in ascending order were Cr < Ni < Cu < Zn < As < Pb < Cd < Hg, while their potential ecological risks (Eⁱ_r) in ascending order were Cr < Ni < Zn < Cu < Pb < As <  < Cd < Hg. The results of Pearson’s correlation analysis and Cluster analysis indicated that Cd, Cu, Hg, Zn, Pb and As in sediments may come from discharges of a Nonferrous Group located beside to upstream of Dongdagou, whereas Cr and Ni were identified from natural source. The result of potentially toxic elements immobilization showed that the leached concentrations of As, Pb, Zn and Cd in sediments were significantly lower, decreasing greatly pollution risk and illustrating a wonderful stabilization performance.