Distribution, Source Apportionment, and Risk Assessment of Heavy Metals in Surface Waters from a Glacier Basin on the...

Heavy metals in surface waters pose significant risks to aquatic ecosystems and human health. In this study, a comprehensive analysis of multiple heavy metals (V, Cr, Mn, Co, Ni, Cu, Zn, As and Cd) was performed using extensive surface water samples from the Meili Snow Mountains glacier basin, southeastern Tibetan Plateau. Results showed that heavy metal concentrations were higher in glacier meltwater than in downstream rivers, with significant variability observed in both the glacier basin (0.00300-33.4 μg/L) and downstream rivers (0.00500-2.85 μg/L), attributable to local geological processes and regional atmospheric deposition of transported particulate pollutants. Elevated total heavy metal concentrations at Sinong River and Qunatong River were primarily driven by uneven distribution of specific metals, likely from both anthropogenic and natural sources. Principal component analysis extracted three components that grouped heavy metals into Mn-Co-Ni-Cd, Cu-Zn, and V-Cr associations, indicating mixed geogenic and anthropogenic sources, with long-range atmospheric transport from surrounding polluted regions being a notable contributor. Risk assessments indicated low ecological risks (ERI < 150) and safe non-carcinogenic risks (HI < 1), with children exhibiting higher susceptibility than adults and As being the primary contributor. Although the carcinogenic risks (TCR: 10^-6-10^-4) were acceptable, ingestion of As and Ni posed higher risks, especially in the Yubeng River basin for adults. These findings provide valuable insights for water resource management and health protection in the southeastern Tibetan Plateau.