Characterization and assessment of groundwater from Obafemi Awolowo University campus, southwestern Nigeria

Abstract

This study deduced groundwater contaminant sources and the processes controlling groundwater chemistry using Principal Component Analysis (PCA), rock source deduction and Water Quality Index (WQI), all with a view to characterize and assess the groundwater. Groundwater sampling was performed at Obafemi Awolowo University (OAU), Ile-Ife, Southwestern Nigeria. A total of 41 groundwater samples were collected in dry season (November) and subjected to physicochemical analyses. Twelve (12) parameters (pH, TDS, electrical conductivity, temperature, Calcium, Magnesium, Sodium and Potassium, Bicarbonate, Chloride, Sulphate and Nitrate) were analysed. PCA analysis highlighted five principle components (PC–I, PC-II, PC-III, PC-IV and PC-V), which explained 82% of the total variance in the hydrogeochemical data. PC-I to PC-V had loading for Ca2+ and SO42−; Na+ and K+; EC and TDS; Mg2+ and HCO3−; and pH and temperature, respectively. The PCA and source rock deductions revealed that the groundwater chemistry is influenced by geogenic effects of weathering and rock-water interaction, and non-geogenic effects of precipitation and organic processes. Based on the WQI assessment, the groundwater quality was adjudged good to excellent.