Delineation of groundwater vulnerability to pollution around dumpsites in Sapele, Nigeria

摘要

Fifteen vertical electrical soundings and six dipole-dipole profiles were conducted to determine the subsurface structure and groundwater vulnerability to pollution around dumpsites in Sapele, Nigeria. The result of the study showed that the subsurface consist of four geo-electric layers composed of topsoil, lateritic sand, fine sand and medium to coarse grain sand. The third and fourth layers were identified as the aquifer layers located at a depth ranging from 4.5-10.0 m. The analysis of the results obtained for the various geo-electric layers revealed that the resistivity values of the aquifer layers below the two dumpsites are lower than those of the control. This fact when compared with the values of the physico-chemical study of the groundwater, showed that the aquifer under the dumpsite is already been impacted. This is due to the inability of the first and second layers to protect the underlying aquifers. It is suggested that the dumpsites be relocated with special attention to the groundwater flow direction to avoid continuous contamination of the groundwater.