Evaluation and characterization of the groundwater quality and hydrogeochemistry of Ogbaru farming district in southeastern Nigeria

Abstract

The aim of this study was to evaluate and characterize the hydrogeochemistry and quality of groundwater (for human consumption) in Ogbaru district, southeast Nigeria. Borehole samples were subjected to physicochemical, bacteriological, hydrogeochemical, and statistical analysis. The physicochemical characteristics of the water were below standard maximum permissible limits for drinking water. Moreover, heavy metals were found in low concentrations (below their permissible limits) in all of the samples. However, majority of the samples have pH values below the allowable limits of 6.5–8.5, indicating they are slightly acidic waters. The dominance of cations and anions is in the order: Ca > Mg > Na > K and HCO3 > Cl > NO3 > SO4 > PO4 > NO2, respectively. Mg–Ca–HCO3 water type dominated the area, constituting about 47.4% of the total samples. Ca–Mg–HCO3 water type constituted about 16%; Mg–Ca–Na and Ca–Mg–Na–HCO3 water types constituted 10.5% each, whereas Ca–Mg–Cl, Mg–Ca–Cl–NO3, and Ca–Mg types made up 5.2% each. The possible sources and influencers (both anthropogenic and geogenic) of the physical and chemical water quality parameters were identified by correlation and principal component analyses. Although most of the groundwater samples are of good quality based on the physicochemical properties, the presence of coliforms indicates that their quality is questionable and hence not safe for drinking. Therefore, treating them before use is recommended.