Assessing Physicochemical and Heavy Metal Characteristics in Leachate and Groundwater around Pugu Kinyamwezi Dumpsite, Dar es Salaam

This study aimed to investigate the extent and dynamics of groundwater contamination around the Pugu-Kinyamwezi dumpsite in Dar es Salaam, Tanzania. Specifically, it evaluated the physicochemical and heavy metal characteristics of leachate during the dry and wet seasons and assessed its impacts on the surrounding groundwater reservoirs across both seasons. Field sampling of leachate and groundwater was conducted in four directions around the dumpsite during both dry and wet seasons, with sixteen groundwater and three leachate samples collected per season. Physicochemical analyses (pH, TDS and EC) were performed onsite, and heavy metal analyses (Pb, Cr, Cd and Cu) were carried out in the laboratory. Results showed that leachate exhibited higher concentrations of physicochemical and heavy metal parameters during the wet season compared to the dry season. Similarly, groundwater contamination levels were generally higher in the wet season, except for one direction where concentrations were significantly lower during the wet season. Groundwater contamination exceeded WHO drinking water quality thresholds, rendering it unsuitable for consumption. Positive correlations between physicochemical and heavy metal parameters in groundwater indicated waste leaching influence, while decreasing concentrations with distance from the dumpsite highlighted localized impacts. Principal Component Analysis (PCA) revealed significant contributions from surface runoff and direct infiltration. These findings underscore the urgent need for improved waste management and remediation strategies to mitigate