Jornal de Geologia e Geofísica
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Geochemistry and Quality Characterization of Effon Psammite Ridge Spring Water, Southwestern Nigeria

Nwankwoala HO, Nwaogu C, Bolaji TA, Uzoegbu MU, Abrakasa S and Amadi AN

This study evaluates the geochemistry and quality characterization in the Effon Psammite Spring, Southwestern Nigeria. Fifteen (15) water samples were collected from the study area at regular intervals and samples were analyzed in order to determine their quality characteristics. Except for pH values that is mildly acidic to slightly alkaline in some locations, the physico-chemical properties are below the WHO recommended standards for drinking water. The low values of the conductivity are mainly attributed to geochemical processes prevailing in the area. The mean concentration of the cations follows the order: Na+ >Ca2+ >K+ >Mg2+ while for anions, HCO3 - >Cl- > PO3 - >SO4 2- >NO3 -. The water is mildly acidic to alkaline due to dissociation of bicarbonate with the following water types: Na-SO4-Cl, Na- HCO3, Ca-Na-SO4 and Ca-Mg-HCO3-SO4 which are a reflection of geology and climate of the area. The mildly acidic to alkaline indices revealed that the spring water has undergone ion exchange between Na+K ions in the water with Ca and Mg of soil during the residence time of the water. The springs are being recharged from recent precipitation that has low water-rock interactions and low residence time within the aquiferous zones. The hydrochemical trend signifies low mineralized water with low water-rock interactions and residence time. Based on these water types and the presence of Na+, the concentrations of cations are geogenic in origin and might have come from the interaction of water and the rock or introduced from weathering of rocks into the spring water. It is recommended that effective development of springs should involve thorough examination of their seasonal discharges, including during the summer. In case water supply exceeds use, the surplus waters may be stored for future use in horticulture and to irrigate crop land. Moreso since springs are yet to receive substantial attention, utmost care must be taken to protect the Effon Psammite spring from contamination.