Spatial distribution of heavy metals in groundwaters and health risks associated in the Ntem watershed, Yaoundé, Cameroon Available to Purchase

The present study was aimed at bridging the gaps in the knowledge concerning heavy metals (Pb, Cd, Cr, Ni, Zn, Cu, Mn and Fe) concentrations in the groundwaters of the Ntem watershed in Yaoundé. Representative groundwater samples (25 numbers) were collected from five hand-dug wells, and their metal concentrations were assessed as per standard procedures, and deterministic interpolation techniques were used to perform the spatial distribution of heavy metal concentration maps. The ranges of concentrations of these metals in groundwaters were: Pb (0.11–0.34 mg/L > 0.025 mg/L); Cd (0.00–0.08 mg/L > 0.005 mg/L); Cr (0.12–1.33 mg/L > 0.05 mg/L) and Ni (0.11–0.46 mg/L > 0.05 mg/L). Besides, the average metal concentrations in the groundwaters of the sampling sites were in general higher than the prescribed World Health Organization (WHO) norms. The risk assessment indicated that the population concerned are considered unsafe, and are therefore exposed to non-carcinogenic and carcinogenic effects on health. The occurrence of more than permissible levels of heavy metals in the representative groundwaters and their spatial distribution indicate that there is a potential threat from these contaminants to the public health in the Ntem watershed.