Metal enrichment in the tropical estuarine environment and associated health risk assessment using PMF and Monte...

Study of metal enrichment in water and sediment was carried out in the tropical estuarine environment of Sibuti river in northern Borneo, Malaysia. In this study, a novel approach of PMF-Monte Carlo Integration was used to assess the source-oriented health risk that effectively allows source-based mitigation of metal pollution with higher accuracy. Targeted metals (Fe, Cu, Zn, Co, Mn, Cd, Cr, Se, Al, Ba) were modelled using the PMF receptor model and FreeViz projection via Orange ML for source apportionment, where Monte Carlo Simulation (MCS) assessed probabilistic health risks in adults and children. Results showed that erosion and leaching of geogenic formations (peat soil and marine shale, pyrite concretions) significantly contributes to metal enrichment denoted by decade long agricultural deforestation. Higher release and deposition of Se, Cu, and Zn was noted in estuary and were facilitated by Mn and clay minerals. The dominance of sources towards health risk contribution was observed as agricultural effluents (>90 %) > Leaching from Pyrite concretion > Peat soil leaching for adults and children in both mediums. Metal concentrations in Sibuti estuary water were within safe limits for non-carcinogenic risk, with mean THI values of 7.392E-05 (children) and 6.471E-05 (adults). However, TCR values for Cr and Cd exceeded guidelines in 100 % of water and sediment scenarios. Co and Cr in sediments posed non-carcinogenic risks in over 97 % of scenarios for children and 57 % for adults. These findings highlight the need for preventive measures against metal contamination. The results underscore the importance of monitoring and managing metal sources such as agricultural activities along with rapid land use changes.