Hydrochemical Evaluation of Groundwater Resources in Ngbo Areas, Ebonyi State, Southeast Nigeria.

Abstract

The hydrochemical evaluation of groundwater resources of Ngbo Area have been carried out covering parts of Ohaukwu and Ebonyi LGAs of Ebonyi State. The area lies between latitudes 6025’N and 6030’N, and longitudes 8000’E and 8005’E. Geologically, the area is underlain by highly consolidated dark-grey and fissile- brown shales, limestone and mudstones belonging to the Albian Asu River Group. Ten (10) groundwater samples were collected for analysis using Standard sampling procedures. The result which was compared with the World Health Organization and Nigerian Standard shows that the mean concentration of the physical parameters such as pH (6.92), total dissolved solid (15.56), electrical conductivity (15.56), and total hardness (1.0mg/l) of the groundwater of the area are fresh (due to TDS < 1000 mg/l at temperature range of 270C to 300C), dominantly alkaline, moderately hard in some locations such as locations 7 (Umuezaka Ngbo), 9 (Hill Top Pri. Sch., Amoffia Ngbo) and 10 (Ndiulo Umusoke Amoffia Ngbo), possibly due to bicarbonate (HCO3–) concentrations of 340mg/l, 279mg/l, and 335mg/l, and were within the permissible limits for drinking, domestic, industrial and agricultural purposes. High concentration of chloride ions in some of the samples was indicated. This could be attributed to the presence of igneous rocks and the leaching of sewage effluents down to the groundwater system. The dominant order of cations and anions chemistry for most of the analyzed groundwater samples is Ca2+>Mg2+>Na+>K+ and Cl–>HCO3– >SO42-> and NO3– respectively. This is a reflection of high carbonates in the rocks. Proper sewage disposal should be upheld in the area.