Abstract

Geochemical study on groundwater quality was undertaken from Bayankara, Badariya and Old Town areas in Birnin Kebbi, situated in sedimentary basin, northwestern Nigeria. The hydrogeochemical study was carried out on 30 water samples, 10 from each of the 3 locations with the intent to determining the quality of the water sources such as tap water, borehole, and hand-dug well used for drinking and domestic purposes; to determine the causes, sources of the pollutants and suggest solutions towards solving the problem. The 30 water samples were analyzed for major elements and important anions. Atomic Absorption Spectrometer (AAS) was used to analyze the cations while NO3 -, PO4 3- and SO4 2- were determined using Spectrophotometer. Both Fand Clwere determined by titration method. The results show that all the cations Na, K, Ca, Mg, Fe, Cu, and Zn ions have values far less than maximum limit recommended by WHO except Mn ion that exhibits average concentration values in Bayankara 0.39mg/l, Badariya 0.16mg/l greater than 0.05mg/l tolerable limit by WHO standard. However, Old Town area has Mn ion values within the recommended limit. PI index on manganese ion further show that Bayankara is more polluted than Badariya having PI index > 1 probably due to unhygienic conditions of the areas and possibly due to dissolution of manganese mineral present in the sandstone aquifer. The anions analyzed Cl, F, NO3 and SO4 have ion concentrations within the limits of WHO recommended for drinking water with the exception of NH4 and PO4 ion concentration values that are anomalously high in the 3 locations; showing values greater than 0.5mg/l for NH4 and 0.3mg/l for PO4. In Bayankara, average NH4 and PO4 ion concentration values are 3.7mg/l and 0.81mg/l respectively; Badariya, 4.0mg/l and 0.75mg/l respectively, while Old Town is 3.8mg/l and 0.87mg/l respectively. The contaminants resulted from anthropogenic means such as poor hygienic condition from sewage leaching and excessive application of leached fertilizer and manure rich in PO4 and NH4 in farming, aided by tectonic and sedimentary structures that characterize the study areas.