Evaluation of the Spatial Distribution and Human Health Risks of Heavy Metal Pollution in Soil and Groundwater Around Steel Recycling Industry in Kwara State, Nigeria (Published)
Rapid industrialization has resulted in widespread environmental contamination, particularly from steel recycling industries that discharge untreated effluents containing elevated concentrations of heavy metals. This study investigated the spatial distribution and accumulation of heavy metals (Pb, Cd, Cu, Zn, Fe, and Mn) in soil and groundwater samples collected from areas adjacent to steel recycling operation in Kwara State, Nigeria. Soil samples were collected at 10 cm depth from five locations, while water samples were obtained from six hand-dug wells during a six-month period (July–December, 2025). Physicochemical parameters and heavy metal concentrations were analyzed using standard methods and atomic absorption spectrophotometry. Results revealed that soil samples exceeded Federal Environmental Protection Agency (FEPA) permissible limits for Zn (413.3 ± 0.06 mg/kg), Cd (222 ± 0.05 mg/kg), Mn (894.74 ± 0.03 mg/kg), Fe (1293.22 ± 0.04 mg/kg), and Pb (33.4 ± 0.3 mg/kg). Groundwater analysis indicated pH values ranging from slightly acidic to alkaline (6.63–7.81), with heavy metal concentrations exceeding WHO guidelines, particularly for Pb (0.80–0.81 mg/l) and Fe. Wells situated closest to the industrial facility exhibited the highest contamination levels, demonstrating a proximity-dependent pollution gradient. Statistical analysis using ANOVA and Duncan’s multiple range test (p < 0.05) confirmed significant temporal and spatial variations in metal concentrations. Health risk assessment revealed significant non-carcinogenic risks (HI > 1) for children and adults through multiple exposure pathways, with carcinogenic risks exceeding acceptable limits (CR > 10⁻⁴) for Pb and Cd. The findings indicate severe soil and groundwater contamination rendering them unsuitable for agricultural and domestic purposes, posing significant health risks to local communities through direct and indirect exposure pathways.
Keywords: Heavy Metals, Soil Samples, groundwater samples, health risk assessment., steel industry