Hydro-geochemical Study of Groundwater in Ajegunle Area in Oyo Town, Southwestern Nigeria

Abstract

The demand for groundwater is high due to its availability and relative purity and it is the major source of fresh water in Ajegunle area in Oyo town, southwestern Nigeria. In the light of this, hydrochemical studies was carried out by analysing the major ions from representative seventeen (17) samples collected from selected hand-dug wells across the study area. The results showed that the pH ranged from 5.6 - 8.0 with an average of 6.37 , total dissolved solids (TDS) was between 40  and 480 mg/L with an average of 278.2mg/L, and electrical conductivity (EC) from 90us/m to 970us/m with an average of 565.8us/cm. Concentration of major ions in mg/L showed that  calcium ranged from 16.00 to 62.03; magnesium, 13.73 - 34.32; sodium, 10.02 - 15.01; potassium ranges ranged from 7.11 - 9.96 ; bicarbonate  14.00 -  260.00, sulphate 10.00 - 40.00; nitrate 0.83- 8.32. From average concentrations, the order of ionic dominance was Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ for cations and HCO₃- > Cl^- > SO₄^2- > NO₃ for anions. From Piper plot the hydrochemical facies of sampled water is mainly Ca-HCO₃. Though, the concentrations of the analysed ions as well as the ancillary parameters were not of health concern, there is need for further studies in assessing the microbial counts as well as trace elements concentration before the water can be said to be suitable for drinking purpose.