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Abstract
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Article Information:
Imaging and Detecting Underground Contaminants in Landfill Sites Using Electrical Impedance Tomography (EIT): A Case Study of Lagos, Southwestern, Nigeria
J.A. Olowofela, O.D. Akinyemi and A.S. Ogungbe
Corresponding Author: Ogungbe Abiola
Submitted: 2011 November, 17
Accepted: 2011 December, 27
Published: 2012 March, 01 |
Abstract:
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This study presents an imaging technique called Electrical Impedance Tomography (EIT) which is
a purely medical imaging technique, for imaging and detecting underground contaminants in landfill sites in
Abule Egba and Solous 1 dumpsites in Lagos, Nigeria. Conventional electrical imaging technique using Wenner
configurations was also carried out on each of the sites in order to validate the EIT results. Three methods of
impedance data acquisition techniques were employed; neighboring, opposite and cross and the inversion of
the data was accomplished using the Electrical Impedance and Diffuse Optical Reconstruction Software
(EIDORS) version 3.0 toolkit for MATLAB to obtain three - dimensional conductivity profiles. The scheme
utilized in this work is a forward solution solved with a mesh of 768 finite elements with 205 nodes. The
conventional electrical resistivity data was inverted using DIPRO software to obtain 2D resistivity structures.
With the aid of the 3D impedance tomograms, two distinct contaminant plumes were mapped and identified
within and around the landfills. These are highly conductive leachate contaminant plumes with conductivity
values ranging from 1,000 to 5,000 S/m and highly resistive gaseous contaminants (with negative conductivity
values on the tomograms) which are probably due to landfill gases as a result of the anaerobic decomposition
of the landfill organic wastes. These contaminants are migrating in depths and distance away from the landfills
into the aquifer. The study shows that the soil and groundwater system had been contaminated beyond the depth
of 50 m in the study areas.
Key words: Aquifer, contaminants, electrical impedance tomography, groundwater, landfills, leachate,
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Abstract
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Cite this Reference:
J.A. Olowofela, O.D. Akinyemi and A.S. Ogungbe, . Imaging and Detecting Underground Contaminants in Landfill Sites Using Electrical Impedance Tomography (EIT): A Case Study of Lagos, Southwestern, Nigeria. Research Journal of Environmental and Earth Sciences, (03): 270-281.
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ISSN (Online): 2041-0492
ISSN (Print): 2041-0484 |
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