Ecological and health implications of trace metal pollution in surface waters of Ondo City, Southwest Nigeria

This study presents a comprehensive assessment of metals in surfacewater of Ondo Town, Nigeria. Surfacewater samples (n = 20) were collected and analyzed for physicochemical parameters. Physical parameters include pH, temperature (oC), electrical conductivity (EC) and total dissolved solids (TDS) were measured using a handheld pH meter on field while metals (Fe, Pb, Cu, Cr, Mn, Zn, Ni, Co, and Cd) were analyzed using flame atomic absorption spectrophotometry (FAAS). Results revealed that the values of pH in the surfacewater is between 6.93 and 7.61 while the temperature is between 28.50°C and 33.24°C. TDS in the water is between 77.00 mg/l and 1446.00 mg/l while EC is between 152.00 µS/cm and 2902.00.00 µS/cm. The study showed elevated concentrations of Fe (0.12–7.54 mg/l), Pb (0.01–0.99 mg/l), Cr (0.01–0.13 mg/l), and Cd (0.002–0.004 mg/l) exceeding WHO limits in several samples. Multivariate statistical analyses identified weathering, agricultural runoff, and industrial effluents as major contamination sources. Pollution indices indicated moderate to very high contamination. Potential ecological risk assessment (PERI) highlighted considerable risks from metals. Health risk assessment revealed higher non-carcinogenic risks (HQ > 1) for children due to Pb and Co exposure. The study underscores the need for stricter industrial regulations to mitigate contamination.