Source-oriented probabilistic health risk assessment of surface water potentially toxic elements and essential trace elements in the Tethyan-Himalayan Tectonic Domain

The accurate identification of pollution sources for potentially toxic elements (PTEs) and essential trace elements (ETEs) in surface water, coupled with the establishment of a source-oriented health risk assessment framework, is essential for effective pollution management. Despite this, significant research gaps persist regarding the combined pollution characteristics and source-risk relationships of PTEs and ETEs in high-altitude regions. This study focused on the Tethys-Himalayan tectonic domain in Tibet, employing an integrated methodology (APCS-MLR, PMF, HRA, and MCS) to systematically assess pollution characteristics and associated health risks. The findings revealed generally favorable water quality, although localized enrichment of arsenic (As) (up to 257.72 μg/L) and selenium (Se) was observed. Both the APCS-MLR and PMF models identified four primary source categories: natural geological sources (As, Se, Zn), climate-driven remobilization sources (Cd, Hg), industrial-traffic mixed sources (Pb, Cu), and anthropogenic agricultural sources (Fe, Cr, Mn). The health risk assessment indicated that non-carcinogenic risks were generally within acceptable limits, whereas the carcinogenic risk from As exceeded the safety threshold (1 × 10^-4) in 83.67 % of children and 82.59 % of adults. Notably, the probabilistic risk assessment provided higher risk estimates compared to traditional deterministic methods, suggesting that the latter may underestimate actual risks. These results highlight the significant role of natural geological processes in the enrichment of As and offer a robust scientific foundation for managing surface water pollution in high-altitude regions.