Pollution risk of groundwater in rivers state: a function of lithology and pollutant load of the area

The hydrogeological-environmental study undertaken in this work was to establish the influence of lithology and pollutant loading to the vulnerability and pollution risk of groundwater. Five case study centers were chosen for a comprehensive work. Water samples were taken and measured for taste, colour, odour, hardness, turbidity, temperature and pH. Geoelectric cross-sections from VES and core samples from borehole drilling at the study sites were used to establish the lithologic sequence of the area. Chemical analysis was done by sequential extraction process and FAAS analytical tool. The results from the chemical analysis showed exceptionally high pollutant concentrations at the ground surface indicative of high pollutant loading. However, the concentrations decreased exponentially with depth, which is attributed to the adsorption ability of the clayey, fine sand and organic formation materials of the top layers of the lithologic sequence that adsorbed and occluded the pollutants as they percolate towards the groundwater. This phenomenon, the tested properties of the water samples and the exceptional high pollutant loading; make the groundwater of the study area at the moment less vulnerable but of high pollution risk.