A hydrochemical evaluation of ionic abundance in groundwater systems in Port Harcourt City, Southern Nigeria was carried out. Thirty two (32) groundwater samples were analysed for their physical and chemical properties. The average temperature of the groundwater samples is 29oC. The water is slightly acidic with pH values ranging from 4.28 – 7.72 while Eh ranges between 26.44 to 197mV. Electrical Conductivity (EC) values ranges from 28µS/cm to 717.40µS/cm. Elevated EC values in some locations are indicative of high ionic activities as well as salinity and suggest possible pollution of groundwater. Chloride concentrations in some boreholes are up to 710mg/l, which shows saltwater encroachment at those locations. The Total Dissolved Solids (TDS) ranges from 12.60mg/l – 401mg/l, respectively. Besides pH, Fe, TDS and EC (in some locations), all other parameters fall within the WHO desirable and maximum permissible limits for drinking and other purposes. Thus, the groundwater in the area is low in dissolved constituents, soft and acidic. When treated for pH, Fe2+, Mn, Zn, Cu, and Pb, in the locations affected, the water would be suitable for domestic purposes. The analytical results show the abundance of the ions in the following order: Mg > Ca > Na > K = Cl > SO4 > HCO3 > NO3. Chloride is the dominant anion found in the groundwater of the study area. For determining groundwater types and visualizing trends of groundwater chemistry, Piper trilinear diagrams reveal that there is a mixture of two types of water with variable concentrations of major ions. These are: Ca – Mg-Cl-SO4 type and Na – K – Cl – SO4 type water. The second water type is also influenced by NO3. This means that groundwater in the area is mainly made up of mixtures of earth alkaline and alkaline metals. Chloride is the dominant anion followed by sulphate. This study therefore, provides the basic tool for sustainable groundwater management in the context of quality assessment. It is recommended that regular, systematic, comprehensive and sustainable groundwater quality monitoring in the study area be carried out.
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