A pollutant transport modeling for tracking lead and mercury contamination.

Abstract

This study developed a pollutant transport modeling framework to track lead and mercury contamination in the River Okame catchment, a region significantly impacted by artisanal and small-scale gold mining activities. Using the Soil and Water Assessment Tool (SWAT), hydrological and pollutant transport processes were modeled to assess the extent of heavy metal contamination. Data on hydrology, land use, soil types, mining activities, and heavy metal concentrations were collected and integrated into SWAT for simulation. Model calibration and validation were conducted using observed water quality and streamflow data to enhance prediction accuracy. The findings revealed alarmingly high levels of lead and mercury in dissolved-bound forms, exceeding recommended environmental and health safety thresholds. Pollutant transport analysis identified critical contamination hotspots, primarily near active mining zones and downstream deposition areas. Scenario-based modeling demonstrated that unregulated mining practices and land-use changes significantly exacerbate heavy metal pollution, particularly during high-flow events. The study highlights the urgent need for mitigation measures, including use of borax and reduction in the amount of mercury level to reduce contamination risks. The results provide a scientific foundation for policymakers and stakeholders to implement sustainable management practices aimed at safeguarding water quality, aquatic ecosystems, and public health in the River Okame catchment.