Implementing Electrical Resistivity Tomography to Delineate Soil Contamination Zone, Southern Baqubah City, Iraq

Abstract

An electrical resistivity tomography survey was carried out in Diyala University campus, southern Baqubaa city, Iraq. The main aim of this study is to evaluate the efficiency of electrical resistivity tomography to detect the buried sewage system as well as to assess its environmental impact on the surrounding soil. Six parallel resistivity profiles were carried out at a perpendicular direction to the axis of the sewage system. Two-and three-dimensional geoelectrical models were constructed to determine the distribution of resistivity and its relation with both buried structures and contaminated zones. The results showed an intermediate relative resistivity zone (6-10 Ω.m) and several rounded very low resistivity zones (< 1 Ω.m), identifying the underground sewage system and contaminated soil, respectively. Based on variations in resistivity values, six holes (h1, h2, h3, h4, h5, and h6) were drilled. A total of six soil samples at 1.5m depth (1 sample per hole) were collected for heavy metals concentrations analysis. The results of the chemical analysis showed a higher concentration of heavy metals near the septic system than that the area away from it. Much lower resistivity zones (<1 Ω.m) and the higher concentration of heavy metals observed near septic system indicate the impact of contamination by migration from the septic tank into the nearby soil. The results of this study confirm the efficiency of electrical resistivity tomography for detecting a buried object and mapping contaminated zone for engineering and environmental applications.