Environmental contaminants due to dumpsite leachates and the possible implications on public health

Dumpsite leachate plumes (DLPs) remain one of the major threats to environmental health, compromising the integrity of soil, surface-groundwater systems, and human health. This study exploits three main geophysical methods (electrical resistivity, magnetic survey, and Very Low Frequency) and hydrochemical analysis (HCA) alongside an oral interview to evaluate the impacts of the DLPs on the immediate environment and the associated health risks within Kaduna Metropolis, Nigeria. Based on geophysical investigations, the subsurface resistivities significantly vary between 2.3–9.2 and 17–114 Ωm, the total magnetic intensity (TMI) varies between 37,600–44,500 and 31,095–37,300 nT, while the equivalent current density (ECD) varies between 30.0–45.0 and – 50 to 30, respectively. Low resistivity, high ECD, and high TMI zones were delineated and mapped as leachate plume-accumulated regions, occurring within the depths of 0.0–7.0 m. The geophysical data highlight zones with elevated magnetic anomalies, resistivity contrasts, and conductive anomalies linked to the suspected DLP accumulated zones. HCA examined the contents of trace elements in the leachate plumes and groundwater samples independently, which vary considerably between 11.17–21.73 and 0.017–2.919 mg/l, respectively. The combined data shows that nearly 75% of the populace residing within a 200 m radius of the investigated dumpsites are potentially exposed to trace elements with (Fe > 1.5, Pb > 1.2, Cd > 0.08, Cr > 0.6 mg/l) in groundwater and (Fe > 2.0, Pb > 1.6, Cd > 0.5, Cr > 1.0 mg/l) in surface water. In addition, the leachate plume contaminants have significantly endangered the integrity of the subsurface in nearly 50% of the area within a 200 m radius of the dumpsites to a depth of > 3.0 m, which inversely compromises the regional groundwater and public health systems. Based on the findings of this study, a safe depth/distance was examined and suggested as a temporary solution. Also, for geophysical standardization, it requires that drinking water sources should be located at least 15 m deep in the soil and 100 m away from dumpsites. Similarly, open and unlined dumpsites should be avoided, while sanitary landfills should be sited at least 6 m above the water table. In conclusion, the overall integrity of surface/groundwater and public health status is largely determined by the overall sanitation of its ambient environment.