Groundwater quality and its suitability for domestic and agricultural uses in Wilberforce island, southern Nigeria

Hydrogeochemical analysis of groundwater samples collected from parts of the Wilberforce Island in Bayelsa State, Southern Nigeria has been carried out in an attempt to assess the suitability of the groundwater for domestic and agricultural purposes in the area. The study was based on thirteen groundwater samples collected from domestic boreholes analysed for some physical and chemical constituents including electrical conductance, pH, total dissolved solids (TDS), alkalinity, hardness, Na+, K+, Ca2+, Mg2+, Fe, Cl-, SO42-, NO-3, and HCO3. The quality of the groundwater samples was evaluated with reference to WHO standards. The results obtained showed that the concentration of dissolved major cations and anions in the groundwater vary spatially and mass abundance was in the order of: Ca2+ > Na+ > Fe >K+ > Mg2+ for cations and Cl- > HCO3 - > CO3 - -> NO3 - > SO42-for anions. The concentration of these ions as well as such parameters as total hardness and TDS are below the World Health Organisation (WHO) standard for domestic uses of water in over 80% of the samples. However, iron was over 3000% higher than the WHO permissible limits. The groundwater in the area is fresh, high salinity and low sodium in nature. Ca– HCO3 and Ca– Cl– HCO3 are the dominant hydrochemical facies of the study area. Alkali earths metals (Ca2+ and Mg2+) and strong acids (Cl- and SO42-) are slightly dominating over the alkali metals (Na+ and K+) and weak acid anions (HCO3- and CO32-).KEYWORDS: Groundwater quality, hydrogeochemical, sodium percent, sodium adsorption ratio, Wilberforce Islan

Identification of hydrogeochemical processes in groundwater using major ion chemistry: a case study of Yenagoa and environs, southern Nigeria

Hydrogeochemical studies were carried out in Yenagoa city and environs, Southern Nigeria in order to assess the chemistry of the groundwater and identify the dominant hydrogeochemical processes and mechanisms responsible for the evolution of the chemical composition of the groundwater. The study approach includes detailed geochemical analysis of groundwater samples collected from domestic boreholes for major constituents such as Ca2+, Mg2+, Na+, K+, HCO3, Cl-, SO4 2-, and NO3- and the hydrochemical data was subjected to multivariate statistical analysis and conventional graphical plots. The results show that most groundwater quality parameters are within World Health Organization acceptable limits for drinking water. The chemical relationships of the ions in Piper diagram identify Ca- Cl, Ca-HCO3 and Na-HCO3 as most prevalent water types. The alkalis exceed the alkaline earths and weak acids exceed the strong acids. The contribution of (Ca + Mg) and (Na + K) to total cations and HCO3 indicates the dominance of silicate weathering as the major source of cations. The plot of Na vs Cl indicates higher Na, derived from silicate weathering process which was also supported by higher HCO3 values. Reverse ion exchange process is also significant in the study area which is indicated by negative Schoeller indices and shifting to the left in the plot of Ca2+ + Mg2+ vs HCO3 + SO4. Furthermore, the plot of Na-Cl vs Ca+Mg – HCO3 – SO4 confirms that Ca, Mg, and Na concentrations in groundwater are derived from aquifer materials. Saturation index of silicate and carbonate minerals indicate undersaturation to oversaturationKEYWORDS: Groundwater, ion exchange, rock-water interaction, saturation index, Yenago