Determination of Magnetic susceptibility of hydrocarbon contaminated soils in Port Harcourt and Bonny Island, Rivers State, Nigeria

In this study, determination of magnetic susceptibility were carried out on 366 soil samples using MS2B magnetic susceptibility meter connected to a computer system using MULTISUS2 software. The soil samples were selected from six sites namely: Shell environment, Nigeria Liquefied Natural Gas environment, Port Harcourt Refining Company James Hart, New Jerusalem and Port Harcourt respectively. Three of the six sites; Shell, NLNG and Port-Harcourt Refining Company environments have their soils contaminated with hydrocarbon. One hundred and ninety two (192) soil samples were collected from these hydrocarbon contaminated sites and 174 from non-hydrocarbon contaminated soil (control samples). The magnetic susceptibility values obtained from Shell environment and for hydrocarbon samples showed higher (enhanced) magnetic susceptibility with average values of 117.54x10-8 m3kg-1 and 2016.39x10-8 m3kg-1 and a moderate magnetic susceptibility for with an average value of 20.83x10-8 m3kg-1 in comparison to magnetic susceptibility values obtained from the control samples whose average values were 2.39x10-8 m3kg-1, 12.42x10-8 m3kg-1 and 3.31x10-8 m3kg-1 for James Hart, New Jerusalem and Port Harcourt respectively. This means that the hydrocarbon sites are highly magnetic which could be indication of pollution. The results of the percentage frequency dependent susceptibility (χFD%) obtained in the hydrocarbon samples showed about 16% of the samples had percentage frequency dependent susceptibility (χFD%) values between 0-2%, 53% had values of χFD% between 2-10% and 31% had χFD% between 10-12% and above while about 21% of the control samples had χFD% values between 0-2%, 58% between 2-10% and 21% between 10-12% and above. The high magnetic susceptibility value in the hydrocarbon soil samples is an indication of pollution due to hydrocarbon deposit. The Government is therefore advised to monitor the location and activities of the oil companies and initiate quick mop up strategies should be put in place in the eventuality of oil spillage

Geophysical Investigation of the Subsurface Fractures Zones Using Vertical Electrical Sounding in Kassa Volcanic Field (KVF) on the Jos Plateau, North central, Nigeria

A geophysical investigation using geo-electrical resistivity method was carried out in the Kassa Volcanic Field (KVF) on the Jos Plateau to reveal the subsurface structural lineaments as indicated in the satellite images covering the area. The electrical resistivity method utilized the Schlumberger technique along 3 profiles. A total of 36 Vertical Electrical Soundings (VES) stations with AB/2 (current electrode spacing) from 1.5 to 215m with intervals of 50m and depth penetration capability of 70m was carried out. The results obtained revealed 3-5 lithologies sequence with thicknesses ranges between 0.1 and 70m and resistivity values of between 34 ?m and 2222 ?m.   Nineteen major fractures at various depths were intercepted at various VES stations and these are probably the zones through which the basaltic lava out poured apart from the central volcanic vent.  The VES results revealed heterogeneous nature of the subsurface geological sequence. The geologic sequence beneath the study area is composed of hard pan top soil (clayey and laterite), weathered basaltic rock layers, partly weathered or fractured and fresh basement rocks. Keywords: Geo-electric section, Subsurface, Vertical Electrical Sounding, Kassa Volcanic Field, Schlumberger Array, Jos Platea