Apreliminary analysis of groundwater chemistry in shallow boreholes, Ughelli, Nigeria

Ground-water samples collected from 25 shallow boreholes in Ughelli, western Niger Delta, Nigeria, have been analyzed to determine major ion chemistry, and to compare the chemistry with that of the eastern Niger Delta. Preliminary results showed that major ions such as Ca²⁺, Mg ²⁺, Na⁺ and Cl occurred in relatively significant quantities in all the samples. The concentrations of these ions are below the standards for drinking water as recommended by the World Health Organization (WHO). As with the landward side of the eastern Niger Delta, the concentration of Ca^2- was found to be higher than Mg²⁺ in all the samples. Chloride occurs in concentrations less than 14 ppm in 50 percent of the samples. Chloride concentration is higher in the remaining 50 percent of the samples, becoming greater than 40 ppm, which may indicate minor saltwater encroachment. However, only 20 percent of the samples haveNa/Cl ratios that are below the values for seawater and freshwater. The results suggest that shallow groundwater in Ughelli is far enough inland to be beyond the influence of seawater from the Atlantic Ocean. As with the eastern Niger Delta, 60 percent of the samples analyzed had iron concentrations higher than the acceptable WHO standard of 0.3 ppm. As the source of the iron in the Niger Delta is not completely understood, further research is recommended in this area.