Environmental and health hazards of heavy metal concentrations in Ota and Agbara industrial areas, Ogun State, Nigeria

The present study evaluates the heavy metal concentration(s) in groundwater and pollution from the Agbara and Ota industrial areas of Ogun State. A total of 64 groundwater samples were collected randomly in dry and wet seasons during the sampling period in July and September, November and December, 2019, respectively. Samples were analyzed for chemical parameters using a standard procedure. The samples were examined for six heavy metals, after which the data were subjected to descriptive statistics. The contamination factor (CF) and Pollution Load Index (PLI), I-geo, and Heavy Metal Index (HPI) were also carried out to process the data. Furthermore, Principal Component Analysis (PCA) was used to verify the sources of pollution. Mean concentrations (mg/L) of the these heavy metals in Agbara and Ota locations were Pb(0.28 ± 0.04 and 0.09 ± 0.13), Fe (0.09 ± 0.02 and 0.99 ± 0.04), Cr (0.16 ± 0.02 and 0.02 ± 0.01), Cu (0.01 ± 0.01 and 0.03 ± 0.02),Cd (0.03 ± 0.01 and 0.01 ± 0.00), and (Ni 0.04 ± 0.01 and 0.07 ± 0.02), respectively. Concentrations (mg/L) of Pb (0.28 ± 0.01), Cd (0.03 ± 0.01), and Cr (0.16 ± 0.02) in Agbara sampling points, as well as Fe (0.99 ± 0.01) in Ota, were greater than the WHO permissible limit for drinking water. Heavy metal concentrations were found to increase in the order of Pb > Cr > Fe > Ni > Cd > Cu and Fe > Pb > Ni > Cu > Cr > Cd for Agbara and Ota locations, respectively. Pollution spatial distributions of HPI ranged from 171.25 to 734.11 and 95.11 to 1393 for Ota and Agbara, respectively. Above the critical PLI value of 100, these values suggest contamination on groundwater sampled with Agbara locations displaying more contamination. PCA further showed strong positive loading for Pb, Fe, and Cr with negative loading for Cu (Factor 1), loading for Cd, Ni, Cr⁻ (Factor 2), and positive loading Cu, Pb with negative loading of Fe (Factor 3) represents industrial pollution sources, industrial effluents, and suspected geologic and industrial sources, respectively.