Subsurface Geophysical Investigation and Physiochemical/Microbial Analysis of Groundwater Contaminant in Ota, Southwestern Nigeria

Geoelectrical imaging of the subsurface to investigate groundwater contaminants in a sedimentary environment like Ota, South-western Nigeria was carried out. The 2 – Dimensional electrical resistivity survey method for the subsurface imaging was done by engaging the Wenner array configuration using PASI Resistivity Meter in the surface measurement. The vertical electrical sounding (VES) was also done using the Schlumberger array configuration to determine the depth to the aquifer layer. The DIPRO software and the WIN-Resist application software were used for the interpretation of the 2 – D resistivity data and VES data respectively. Both Hydrochemical and Microbial analyses were done to test for the presence of heavy metals and the estimation of Total Aerobic Bacteria (TAB). From the VES results the depth to the aquifer lies around 20.1m (60.33ft.) of resistivity of 34.1 -m and the 2–D results showed the resistivities as 28.0 -m and 47.0 -m respectively showing that the study area has groundwater potential. For the hydrochemical analysis on heavy metals, the result lies within World Health Organization (WHO) standard for drinking water. But for the microbial analysis, total aerobic plate count of 2.3× for drinking water is high and above WHO standard specification for drinking water.