Qualitative assessment of groundwater from Egbe–Mopa basement complex area, northcentral Nigeria

Abstract

The quality of groundwater from the Egbe–Mopa area of the Basement Complex of Nigeria has been assessed. Hydro-geochemical analyses and evaluation studies were conducted on twenty water samples, three from boreholes and seventeen from hand-dug wells. The evaluation involved correlation matrix, multivariate analysis (principal component analysis), and comparing the hydro-geochemical data with various standards. The descriptive statistical tests revealed that the principal controlling processes of the groundwater chemistry are hydrolysis of silicate and sulphide minerals and anthropogenic processes. The anthropogenic sources include domestic wastes, and agricultural activities. Based on the hydro-geochemical data, three hydro-geochemical facies were identified, namely: Ca²⁺–Mg²⁺–HCO₃ ⁻, Na⁺–K⁺–HCO₃ ⁻ and Na⁺–K⁺–Cl⁻–SO₃ ²⁻. The Na⁺–K⁺–HCO⁻³ has the highest percentage of occurrence (70%) followed by Na⁺–K⁺–Cl⁻–SO⁻³ (20%) and the least, Ca²⁺–Mg²⁺–HCO⁻³ with 10%. The facies analyses indicate that the groundwater in the area is predominantly recharged by infiltration from precipitation and high occurrence of water–rock interactions. The geochemical data also reveal that the groundwater from the area did not satisfy the standard for drinking purposes; it, however, satisfied the standard for agricultural purposes (especially for irrigation and livestock farming).