Assessments of hydrochemical quality and\r\nrecharge source are critical components of sustainable\r\ngroundwater resources evaluation and management, especially\r\nin complex weathered/fractured crystalline bedrock\r\nterrains. Assessment of the weathered/fractured basement\r\naquifer of Ekiti area, SW-Nigeria was undertaken with\r\nemphasis on hydrochemical quality and stable isotope\r\ncharacterization of shallow groundwater system. The study\r\napproach involved field sampling and in situ measurements\r\nof physico-chemical parameters followed by hydrochemical\r\nand stable isotope analyses of the water samples. In situ\r\nmeasurements revealed EC value of 43ââ?¬â??995 lS/cm\r\n(av 431.96 lS/cm) and total hardness of 31.3ââ?¬â??295.1 mg/L.\r\nThe pH of the water sample ranged from 7.0 to 8.9 (av 8.00).\r\nThe concentrations of the major cations are in the order of\r\nCa2?[K?[Na?[Mg2? with their respective average\r\nvalues of 33.35, 25.61, 24.91 and 8.7 mg/L respectively\r\nwhile that of the anions are in the order of\r\nHCO3\r\n-[Cl-[SO4\r\n2-[NO3\r\n- with their respective\r\naverage values of 165.44, 31.85, 21.27 and 5.44 mg/L\r\nrespectively. However, the results of stable isotope analyses\r\nrevealed d18O value of -4.2 to -2.1 %and dD of -22.3 to\r\n-10.2 %, suggesting meteoric water source (recent precipitation\r\nwater recharging the associated shallow basement\r\naquifer) while the estimated deuterium excess of\r\n6.80ââ?¬â??11.00 % (av 9.6 %) suggested little or no imprint of\r\nkinetic evaporation. Furthermore, the overall hydrochemical\r\nprofiles revealed the main hydrochemical facies as Ca(Mg)-\r\nHCO3 (dominant) and Na(K)-HCO3 (minor) water types\r\nwhich can be attributed to dissolution of minerals in the\r\nvarious rock units in the study area. Conclusively, the overall\r\nhydrochemical and stable isotope evaluations revealed a\r\nrecharge predominantly derived from meteoric (rainfall)\r\nsource while the corresponding low TDS is a reflection of\r\nlow waterââ?¬â??rock interaction and limited migratory history of\r\nthe shallow groundwater system in the study area.
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