Hydrogeochemical imprints and spatio-temporal health risk assessment of lead in drinking water sources of Abeokuta, south-western Nigeria

Water samples were obtained from 63 boreholes around Kuto, Abeokuta, Nigeria, and analysed for some physicochemical parameters and heavy metals. The mean concentrations of TDS, Alka, F−, Fe, Mn, Pb, Zn, Ca2+, K+, Mg2+, Na+, SO42−, SiO2, HCO3−, Cl−, and CO32− were 1136, 27.45, 1.232, 0.521, 0.035, 0.013, 0.286, 78.48, 5.796, 89.91, 193.5, 298.3, 3.671, 411.3, 181.3, and 15.81 mg/L, respectively. Furthermore, the hydrochemical signatures influencing the dissolution of ions in the water samples were obtained, and the empirical Bayesian Kriging prediction model was used to validate the spatial distribution of the HM contaminants within the study region. 42.9% of the groundwater samples has lead concentrations exceeding the WHO threshold for drinking water. The PC/FA produced principal factors, and the hydrochemical facies verified the ion exchange mechanism, linking water quality parameters to geogenic sources (weathering, dissolution, leaching), and anthropogenic emissions from agricultural activities. Health risk investigation revealed that the highest hazard quotient (HRQtot) values for the specified heavy metals were observed at SMP18, SMP5, SMP10, and SMP21, respectively. Carcinogenic risks for adults after the exposure were unacceptable (CRcum > 1E−6) for SMP4, SMP6, SMP7, SMP10, and SMP21. SMP21 presented the highest CRcum (2.62E−6 ± 8.71E−4), while the cumulative carcinogenic risk (CRcum) for children that exceeded the limit was as follows: SMP21 < SMP9 < SMP13 < SMP5 < SMP11 < SMP10 < SMP7 < SMP6 < SMP4 < SMP21. Thus, the scenario calls for adequate water treatment strategies in order to safeguard the health of residents.