Hydrofacies Attributes and Quality Status of Groundwater Systems in Eastern Niger Delta, Nigeria

Abstract

Niger Delta hosts a lot of oil producing and servicing companies. The activities of these companies in last 55 years have negates the water resources in the area, hence the need to assess the pollution level. Hydrofacies and water quality of the coastal plain-sand in Eastern Niger-Delta, Nigeria was investigated in this study. The study is aimed at establishing the water facies as well as ascertaining the overall quality status of groundwater systems in the area. Hydrogeological investigations show that the aquifers in the area are largely unconfined sands with intercalations of gravels, clay and shale. The observed wide ranges and high standard deviations and mean in the geochemical data are evidence that there are substantial differences in the quality of the groundwater system within the study area. The plot of the major cations and anions on Piper and Durov diagrams indicated four hydrochemical facies in the area: Na-Cl, Ca-Mg-Cl, Na-Fe-Cl and Na-Fe-Cl-NO3. Heavy metal enrichment index revealed 12 elements in the decreasing order of: Fe > Ni > Cu > Zn > Mn > Cd > V > Co > Pb > Cr > As > Hg. The study identified high iron content, acid-rain, hydrocarbon pollution (gas flaring and oil spills), use of agrochemicals, industrial effluents and poor sanitation as contributors to the groundwater deterioration in the area. The first factors is from natural source as a result of downward leaching of marcasite mineral contained in the overlying lithology into the shallow water table while the other factors are results of numerous human activities domiciled in the area. Due to the effects of acid-rain in the area, the need to eradicate gas flaring and oil spills in the area was advocated.