Polycyclic Aromatic Hydrocarbons (PAHs) Load and Geo-Electric Characterization of Soils from Ogale Community, Eleme, Rivers State, Nigeria

Abstract

Abstract The aim of this study was to evaluate the polycyclic aromatic hydrocarbons load in soils of Ogale community, Rivers State, Nigeria and as well delineate the lateral and vertical extensions of the soils and groundwater. Geo-electric characterization of the soils and groundwater, using Electrical Resistivity methods (vertical electrical sounding, VES by Abem Terrameter and Gas chromatograph - Flame Ionization Detector (GC-FID) for finger-print was employed. The interpreted VES results revealed four geo-electric subsurface layers. The first layer which has a resistivity value of 60Ωm and a thickness of 2.0M was interpreted as top soil. Underlying the first layer is the second layer which had a resistivity value of 122Ωm with a thickness of 3m, interpreted as lateritic sand. The third layer had a resistivity value of 750Ωm and a thickness of 9.0m, and is interpreted as coarse sand. The fourth layer which had a resistivity value of 1255Ωm and a thickness of 49m is interpreted as very coarse sand. Borehole one was used as control and it is 1.85km away from the Resistivity sampling points. The results revealed that the presence of C10-C40 hydrocarbon which indicates un-weathered to fresh hydrocarbon in parts of the study area and heavy metals were below detection limits. The vulnerability of the aquifer to hydrocarbon contamination was due to high permeability, unconsolidated coarse grained and poorly sorted sands, of the vadose zone as well as shallowness of the aquifer. It is recommended that boreholes in the study area should be of deeper depths, and well constructed to avoid contaminated water from the polluted zone entering the borehole through the annulus.