Geophysical, hydrogeological and laboratory assessment of groundwater quality and its health implication in some urban communities in cross river state

Abstract

The electrical resistivity technique which involved the Schlumberger depth sounding method, electrical resistivity tomography and geochemical analyses of water samples collected from boreholes were used to investigate the quality of groundwater in some urban communities in Cross River State, also the health implication of the said groundwater was also investigated. Forty nine electrical resistivity data were collected, modeled, and interpreted after calibration with lithologic logs. Ten electrical resistivity tomography data was were also collected, modeled and interpreted. Forty nine borehole water samples were collected and analyzed to determine anion, cation concentrations and some physical and chemical parameters, such as water colour, temperature, total dissolved solids, and electrical conductivity. The results show that the lithostratigraphy of the study area is composed of sands, sandstones (fractured, consolidated and loosed), siltstones, shales (compacted and fractured) of the Asu River Group, Eze-Aku Formation which comprises the aquifer units, and the Nkporo Shale Formation. The aquifer conduits are known to be rich in silicate minerals, and the groundwater samples in some locations show a significant amount of Ca2+, Mg2+, and Na+. These cations balanced the consumption of H+ during the hydrolytic alteration of silicate minerals. The geochemical analysis of groundwater samples revealed dominant calcium–magnesium–carbonate– bicarbonate water faces. The groundwater quality was observed to be influenced by the interaction of some geologic processes but was classified to be good to excellent, indicating its suitability for domestic and irrigation purposes.