Victor O. Omonona, Celestine O. Okogbue, Godwin O. Isreal, Rufai Ayuba and Fabian A. Akpah
The hydrochemical characteristics and quality of the shallow groundwater of the Warri coastal aquifer were studied by using chemical composition (groundwater chemistry), graphical plots, ionic ratios, and estimation of ionic delta and seawater mixing index of the groundwater samples. Twenty groundwater samples were collected from hand dug wells and analyzed for major cations like Ca2+, Mg2+, K+ and Na+, anions like 2- 4 SO , HCO- 3 NO- 3 and Cl-; and heavy metals like Pb2+ Ni2+ and Cd2+. Results of the analysis revealed that rock weathering, cation exchange processes and anthropogenic processes are the major contributors to the chemical compositions of the groundwater. The groundwater classified into two water types namely, CaHCO3, and NaCl water types. The estimated seawater fraction ranged from -0.746 to 0.4887 with a mean of 0.34% for NaCl-type water and a mean of -0.105 % for CaHCO3-type water. Seawater mixing indexes ranged from 0.244 to 1.127.Ionic delta, seawater fraction and seawater mixing indices revealed that the groundwater from areas closer to the coast is more impacted by seawater-freshwater interactions than that from the upland areas. Among the physiochemical and biological parameters measured (pH, EC, TDS, TH, SO4, Cl, HCO3, NO3, Ca, Mg, Na, K, Pb, Ni, Cd, fecal coliform, total bacterial,) only nitrate (NO3), sulphate (SO4) and total bacteria (Bac.) have concentrations below the stipulated WHO (1993) guideline values, indicating that the groundwater of the area is not suitable as drinking water.