Hydro-geochemical Attributes and Quality Status of Groundwater in Port Harcourt, Eastern Niger Delta

Abstract

A hydro-geochemical evaluation of groundwater quality status in Port Harcourt City, Eastern Niger Delta was investigated. This was carried out to assess the quality for human consumption and the processes responsible for the modification of groundwater quality. Thirty two (32) groundwater samples were analyzed for their physical and chemical properties. The average temperature of the groundwater samples is 29oC. The water is acidic to slightly alkaline with pH values ranging from 4.28 - 7.72 while Eh ranges between 26.44 to 197mV. Electrical Conductivity (EC) values ranges from 28?S/cm to 717.40?S/cm. Elevated EC and chloride 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 with Total Dissolved Solids (TDS) ranging from 12.60mg/l - 401mg/l. The chemical composition of the groundwater is characterized by high chloride concentration and variations in cation concentrations due to the cation exchange reaction between aquifer characteristics and seawater components. 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. 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. The groundwater is classified into Ca - Mg-Cl-SO4 and Na - K - Cl - SO4 types based on its hydro-geochemical characteristics. 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.