Quality valuation and hydrogeochemical features of groundwater in university campus and its surroundings, south-west Nigeria

Groundwater is an important freshwater source that can be utilized for domestic and many more purposes. This study assesses the quality and hydrogeochemical processes of shallow aquifer units in the Federal University of Agriculture, Abeokuta (Nigeria) and its localities. Groundwater chemistry, multivariate statistical techniques and water suitability indices have been utilized to appraise groundwater quality. To achieve the objective, hydrochemical analysis, water quality index (WQI), irrigation potential index (IPI) and corrosivity index (CI), have been studied. Thirty groundwater samples were drawn from hand-dug wells and analyzed for physico-chemical parameters using standard laboratory methods. Most of the tested quality parameters fell within the global health regulatory organization recommendations for safe potable water. The average abundance order of dominant cations and anions are Na^+>K^+>Ca^2+>Mg^2+ and HCO₃^->Cl^->SO₄^2->NO₃^-, respectively. Subtle alterations in groundwater chemistry were attributed to silicate weathering, ion exchange reaction and slight localized human-induced inputs. Hydrochemical facies analysis using a Piper diagram showed that the dominant groundwater type were NaHCO₃ and mixed CaNaHCO₃, typically associated with rock-water interaction, and recently recharged groundwater influenced by silicate rock dissolution. By the WQI results, 97% of the groundwater samples belong to ‘excellent to good’ category while the remaining 3% (sample OS2) belongs to ‘poor’ water quality. In terms of agricultural usability, over 50% of the groundwater samples were deemed suitable for irrigation. However, concerns were noted in relation to sodium percentage (Na%), soluble sodium percentage (SSP) and kelly ratio (KR), which could impact soil health over prolonged use.