Pollution risk assessment and spatial distribution of potentially hazardous elements in selenium-rich soils in the MenYuan basin of the northeastern Tibetan Plateau

The scientific utilization of selenium(Se)-rich soil necessitates the evaluation of potentially hazardous elements (PHEs) content. Menyuan basin, a representative Se-rich region located on the northern periphery of the Qinghai-Tibet Plateau, was chosen as the research subject. Pollution risk and spatial source analysis was conducted for eight PHEs (As, Cr, Cu, Pb, Zn, Cd, Ni and Hg) using 5297 topsoil samples and 480 deep soil samples. The results showed that more than 50% of the total area has a Se content above 0.24 mg/kg. There are extremely few sampling sites with potentially hazardous elements at risk of contamination, according to single and comprehensive pollution index. Low ecological risk was seen in 93.34% of the topsoil samples. The results show that although the overall level of surface soil pollution in the study area may be deemed negligible. On the surface or in deeper layers, the concentration centers of As, Cr, Ni, Zn, Pb, and other elements show consistency, indicating that underlying parent rocks are the primary source of these elements. The findings presented herein establish a scientific foundation for the secure development and utilization of Se-rich soil.