Hydrogeochemistry and Stable Isotopes (δ18O and δ2H) Assessment of Ikogosi Spring Waters

Abstract

Ikogosi warm spring is a unique tourist centre where warm and cold spring waters flow together. Consequently, understanding the hydrochemical processes and recharge source are critical to the sustainability and management of the warm spring. Hence, stable isotopes (δ18O and δ2H) and hydrochemical study of Ikogosi spring waters was carried out to conceptualize the recharge source and the extent of water-rock interaction on the hydrochemical evolution of the waters. The study approach involved field sampling and in-situ measurements of physico-chemical parameters followed by laboratory hydrochemical and stable isotope analyses of the spring water samples. The hydrochemical analysis revealed that Ikogosi spring water is alkaline in nature with values ranging between 7.4 and 9.0. The TDS ranges from 14.3 to 66.8 mg/L with mean value of 49.2mg/L while the TH is from 6.3 to 39.0mg/L with mean value of 27.61mg/L. All EC values for the sampled spring waters were below 1000µS/cm indicating fresh water. Ca2+ was the dominant cation with value ranging from 2.2-9.6mg/L while Cl- was the dominant anion with value ranging from 88.6-144.0mg/L. The spring water is low mineralized and hydrochemically potable. Rock-water interactions were the dominant processes controlling the major ion composition of the spring while the dominant water was Ca (Mg)-Cl type. Stable isotopes analysis revealed recharge from recent precipitation. Conclusively, Ikogosi spring waters have low EC and TDS along with low total hardness (TH) values suggesting a low mineralized soft fresh water system recharged from recent precipitation with limited residence time.