Integrated Geophysical Investigation in Delineating Extent of Pollution Caused by Poultry Waste at Ilora Area, Southwestern Nigeria

Abstract

An integrated VLF-Electromagnetic and Electrical Resistivity survey was carried out in Odo Abata, Ilora area of Southwestern Nigeria in order to investigate the possible extent of groundwater contamination caused by an indiscriminate accumulation of poultry fecal droppings in a seasonal stream. The poultry fecal accumulation solidifies during the dry season and the percolating water plays a significant role in leachate generation and infiltration during the wet season. When in contact with the subsurface aquifer, the leachate forms a plume which diffuses into the pore spaces of aquifer with high rate of infiltration. Field data were collected using ABEM WADI VLF- EM equipment and campus Tigre Terrmeter. A total of eight VLF profiles, four electrical imaging profiles and two VES points were obtained in the vicinity of the study area. Control profiles and VES point were obtained at 500 m away from the study area. Field data were interpreted using KHFFilt program version 1.1a for VLF, Dipro software for electrical imaging and Winresist version 1.0 for VES data. Interpretation of VLF data showed conductive near surface layers and some fractures at depth. Electrical imaging data however revealed a near surface very low resistivity region which is due to the surface fecal accumulation. VES results showed that the overburden is clayey, and the basement is fractured. Depth to basement ranges from 9.3 – 12.8 m. Poultry fecal accumulation with leachate is mostly restricted to the topmost 6 m of the soil and if not controlled, leachate infiltration may reach the shallow basement with time and contaminate the groundwater system of Odo Abata area.

Keywords: Very Low Frequency Electromagnetic (VLF-EM), Electrical Resistivity, Contamination, Leachate, Fracture

DOI: 10.7176/JEES/9-10-09

Publication date:October 31^st 2019