Influence of Hydrogeochemical Factors on the Natural Water Systems of Uburu-Okposi area, Lower Benue Trough, Southeastern Nigeria, using Geochemical and Multivariate Statistical Methods

Abstract

Abstract The influence of hydrogeological processes on water systems of the Uburu-Okposi area, Lower Benue Trough was investigated to understand the interplay between aquifer materials and the water system resulting in its chemical composition modification. Forty (40) water samples (ground and surface sources) were randomly collected and analyzed for their physicochemical properties. Results from in-situ measured physicochemical parameters are pH: 5.29–8.98, EC: 206–6970 us/cm, and TDS: 112–4690 mg/l. Laboratory results shows Na+ as the dominant cation (4.4–4900 mg/l) with Cl− as the dominant anion (14.4–6300 mg/l). The values were indicative of salinization. Factors influencing water chemistry were determined using Saturation Index (SI), Ionic Ratio, and Bivariate plots. 65% of samples had positive Chloro Alkali Index (CAI) ratio suggesting direct base-exchange reaction as a dominant factor governing water chemistry. CAI 1 & 2 large absolute values show cation exchange as a principal influence on groundwater chemistry. Estimated SI showed Dolomite, Calcite, Aragonite, and Magnesite were supersaturated therefore, they influenced water chemistry. Bivariate plots identified Ion Exchange (carbonate and silicate weathering) as another principal influence on water chemistry. Gibbs plot showed 92.5% samples plotted in the rock–water interaction field with 7.5% plotting within the evaporation-precipitation field. Principal Component Analyses (PCA) extracted six components factors, the first three factors accounted for above 50% of the total variation collectively responsible for the hydrochemical processes in the area via water-rock interactions, carbonate dissolution, and ion exchanges. Conclusively, geogenic factors are the major influence on water chemistry in the study area.