Geostatistical Assessment of Groundwater Quality from Coastal Aquifers of Eastern Niger Delta, Nigeria

Abstract

The quality of groundwater in the coastal aquifer of eastern Niger Delta has been assessed in the present study using Geostatistical techniques. The range, standard deviation and variance of the dataset show that multi-chemical processes are controlling the groundwater quality/facies and their spatial distributions. The overall WQI value was 285.20 and this is an indication that the groundwater in the area is of poor quality. The higher mean values of copper, iron, lead, nitrate, TC, EC, COD, chromium, nickel and zinc are some of the contributors to deteriorating groundwater quality and their presence can be attributed to both natural and anthropogenic sources. Six Factors, accounting for 91.18% of the total variance were identified. Factors 1 (Conductivity, Cl-, TH, TSS, TDS, Na and Mg), factor 2 (Ca, Fe, pH, NO3-, K and SO42-), factor 3 (BOD, COD, PO42-, EC and TC), factor 4 (Cu, F, Mn and Zn), factor 5 (Cr, Pb and Ni) and factor 6 (Ar and Hg) represent the signatures of saltwater intrusion, chemical weathering, leaching and various human activities domiciled in the area. Factors 1 and 2 represents ions with dominant concentration and therefore are the contributors to the groundwater salinity while factors 3 to 6 are indicators of anthropogenic interference. Piper diagram revealed that the water in the area is Calcium-Chloride type, suggesting a marine origin. The usefulness of Geostatistical methods in interpreting the hydrogeochemical data as well as identifying and categorizing pollutants has been demonstrated in this study.