Source-specific health risk assessment of potentially toxic elements in Wular Lake sediments, Kashmir Himalaya: a Monte Carlo simulation approach coupled with an APCS-MLR receptor model.

Wular Lake, a Ramsar wetland in the Kashmir Himalaya and one of South Asia's largest freshwater lakes, is under growing anthropogenic pressure. This study assessed six potentially toxic elements (PTEs: Cr, Ni, Cu, Zn, Cd, and Pb) in 22 surface-sediment samples using contamination indices, ecological and probabilistic (Monte Carlo) health-risk models, and APCS-MLR source apportionment. The geoaccumulation index (Igeo, 1-2) and the Nemerow pollution index (PN) rated every site as moderately to heavily polluted. The potential ecological risk index (RI 66-132, mean 98) indicated moderate ecological risk overall, rising to considerable risk at seven hotspot sites; consistently, the mean Probable Effect Concentration Quotient (mPEC-Q) exceeded 0.5 at 12 of 22 sites, driven by Ni and Cr. Monte Carlo simulation showed no non-carcinogenic risk (HI ≪ 1) and acceptable carcinogenic risk (TCR ≈ 10-5), higher in children, with Cr and Ni dominant. APCS-MLR resolved a chromium-dominated natural source and a mixed anthropogenic source (Pb, Cu, Zn, Cd, and Ni; ∼65% of the load). Targeted control of anthropogenic inputs would curb the controllable risk and support conservation of this Ramsar site, which contributes to several United Nations Sustainable Development Goals (SDGs).