Geoenvironmental investigation of the metallic concentration of groundwaters in parts of Sapele and Warri, Delta State, Nigeria

Hydrogeochemical studies have been carried out in parts of Sapele and Warri Local Government Areas of Delta State in order to determine the different hydrogeochemical facies and understand the groundwater flow regime and its effect on the chemical composition of the groundwater so as to evaluate the anthropogenic effects on groundwater quality in the study area. Twenty-five (25) water samples were taken from Sapele (18) and Warri (7) in one liter plastic cans with temperature, pH, electrical conductivity and Total Dissolved Solids (TDS) determined in-situ. The samples were then taken to the laboratory where the analyses were done using the Varian 220 flame atomic bsorption spectrophotometer. Salinity and chloride in water was carried out in accordance with the merican Petroleum Institute (API-RP) 45. Phosphate, Nitrate, Sulphate, Calcium, Potassium, Sodium, Magnesium and Ammonium were all determined in accordance with the American Public Health Association (APHA) 425C,427C and 417. The analyses carried out indicated the presence of chloride ion as the dominant parameter. Chloride shows a negative correlation with all other parameters thus indicating that its source is from surface saline waters close to those areas with high chloride concentrations. The presence of ammonia in such high concentrations and its strong positive correlation with phosphate supports that it's source is as a result of pollution from sewage. The positive correlation of phosphate, sulphate, nitrate and TDS also indicate pollution from sewage. GPS readings and computation of several hydrogeological parameters showed a SW direction of groundwater flow for Sapele and a SE flow direction for Warri. The presence of ammonium at levels higher than geogenic (geologically related processes) levels is a strong indicator of fecal pollution. Contamination from anthropogenic sources is mainly as a result of waste waters from brines released as by-products of oil exploration activities and leaky septic tanks.