Hydro-geochemical, geospatial, and geophysical assessment of contaminant dispersion and health risks at Ilokun municipal dumpsite, Ado Ekiti, southwest Nigeria

This study employs hydro-geochemical, geospatial, and geophysical methods to assess contaminant dispersion and associated health risks at the Ilokun municipal dumpsite in Ado Ekiti, Nigeria. Soil samples were systematically collected and analyzed for heavy metal concentrations using standard laboratory procedures. Groundwater samples from nearby wells were assessed for physicochemical parameters, including pH, turbidity, electrical conductivity, and total dissolved solids, following World Health Organization guidelines. Subsurface investigations were conducted using electrical resistivity imaging and vertical electrical sounding to map leachate migration and characterize lithological units. Geophysical results revealed resistivity values ranging from 11 to 70 Ωm in the top 5 m, with low resistivity (< 15 Ωm) indicating extensive contamination. Leachate penetration reached up to 8 m but was restricted by a lateritic layer, while anomalies at 70–80 m suggested potential deeper groundwater contamination. Water quality analysis showed turbidity between 12.5 and 35.4 NTU, electrical conductivity from 480 to 1,240 µS/cm, and total dissolved solids from 650 to 1,800 mg/L, exceeding recommended standards. Soil heavy metal concentrations were notably elevated, particularly iron (2,706.78 mg/kg), lead, and zinc. Health risk assessment indicated significant risks to children, with average daily intakes of lead and zinc at 28.25 and 26.05 mg/kg/day, hazard indices of 54.0 and 347.0, respectively, and elevated carcinogenic risks for lead and cadmium. These findings highlight the urgent need for effective remediation strategies to mitigate environmental contamination and protect public health in the dumpsite area.