Spatial Distribution, Ecological and Human Health Risk Assessment, and Quantitative Source Apportionment of Heavy Metals in Stream Sediments of an Arid River, Qaidam Basin, NW China.

Abstract

Under the dual influence of geological background and human activities, heavy metal contamination in riverine ecosystems poses a significant threat to ecological security and public health. This study systematically investigated the contamination characteristics, ecological and health risks, and sources of nine heavy metals (As, Cr, Pb, Cu, Zn, Ni, Hg, Co, and Ti) based on 7395 stream sediment samples collected from the Bayinguole River in the Qaidam Basin. The results indicated an overall enrichment of Co, Ni, Cr, Pb, Cu, Zn, and Ti across the study area, among which Co and Ni were the most prominent, whereas As and Hg exhibited widespread background depletion. Contamination assessments revealed that the basin is overall unpolluted. However, Co exhibited slight regional enrichment, and Cr, Ni, and Pb displayed localized extreme high-concentration anomalies. A coupled principal component analysis and positive matrix factorization (PCA-PMF) model successfully apportioned heavy metal sources into three distinct pathways: natural geological background (67.1%), industrial and mining activities (26.7%), and atmospheric deposition (6.2%). In terms of ecological risk, the basin overall presented a low level of potential threat, with Co identified as the primary risk driver. Health risk assessments demonstrated that children face higher exposure vulnerabilities than adults, whereas localized carcinogenic risks are primarily driven by extreme hot spots of Cr and As. This study provides a solid scientific foundation for water ecological management, targeted regional pollution control, and public health protection in arid inland river basins.