Assessment of Water Quality of Shallow Aquifer Resources of Agbabu, Ondo State, Nigeria

Abstract

Groundwater, through hand dug wells, provide drinking water to an estimated 59 % of Nigerians. There is, however, a growing concern on the deterioration of groundwater quality due to anthropogenic activities. In this study, water quality index (WQI) was used to assess the groundwater quality of Agbabu, while health risk assessment was carried out by calculating the chronic daily intake (CDI), hazard quotient (HQ), hazard index (HI) and carcinogenic risk (CR) of some heavy metals and nitrate. The WQI shows that the groundwater of the area were in the very poor water quality (76 < WQI < 100) and unsuitable for drinking class (WQI > 100). Oral ingestion is the major pathway of risk exposure, accounting for 86.54 % of total exposure to the risk, while dermal contact accounted for only 13.46%. Cd and Cr are the major contributors to non-carcinogenic risk and accounted for 51.07% and 39.51% respectively of the total risk, while Pb, Mn, Fe and NO₃- showed no risk to the population (HQ < 1). There is also a life time probability of contracting cancer due to groundwater contaminated with Cr and Cd in the study area. The groundwater of the area were contaminated mainly by heavy metals, and therefore should be continuously monitored and proper legislation taken to avoid health risk associated with these toxic metals.