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

Abstract

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 (χ_FD%) obtained in the hydrocarbon samples showed about 16% of the samples had percentage frequency dependent susceptibility (χ_FD%) values between 0-2%, 53% had values of χ_FD% between 2-10% and 31% had χ_FD% between 10-12% and above while about 21% of the control samples had χ_FD% 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.