Geochemical evaluation of carbonate aquifers in Ngbo and environs, Ebonyi State, southeastern, Nigeria

The geochemical evaluation of carbonate aquifers in Ngbo and environs has been executed to ascertain the major ion chemistry and quality of waters for domestic and drinking uses. Ten water samples were gathered from pit lakes, hand dug wells, boreholes and rivers. The collected samples were analysed for pH, EC, TDS, Ca 2+ , Mg 2+ , Na + , K + , HCO 3 − , Cl − , SO 4 2− , NO 3 − and PO 4 2− in the laboratory using the standard methods. The results were compared with NDWQS and WHO standards. The physical parameters varied from pH (6.2–8.4), temp. (25.0–26.0 °C), electrical conductivity (4.9–102 µS/cm) and total dissolved solids (25.5–214.2 mg/l). The analysed results revealed the mean concentration of cations and anions in the following order: Ca 2+ > Mg 2+ > Na + > K + > Fe 2+ and HCO 3 − > CO 3 2− > SO 4 2− > Cl − , respectively. Based on the standard limits, about 90% of the waters in the study area is suitable for domestic and drinking purposes. The Piper trilinear, Stiff and Durov diagrams showed that water samples from various locations fall into mixed CaCO 3 2− +HCO 3 type. Various ionic ratio plots show that water sources are from dissolution of minerals in the aquifer media. Geochemical parameters such as Cl − , Na + and K + show good interrelationship with positive factor loadings among the ions.