Advanced electrical diagnostics for monitoring soil contamination: a laboratory-based assessment approach

Soil contamination is one of the vital environmental challenges the world encounters. This study demonstrates the potential of electrical measurements in controlling and limiting the spread of contamination through soils. The current laboratory samples represent shale contaminated by oil containing polychlorinated biphenyls (PCBs). PCBs are serious risk to living organisms, particularly when they reach soils and aquifers. This study aims to show how electrical measurements can serve as a monitor for soil contamination and oil seepage. This contaminant is regarded as a semi-insulating material, whereas shale is supposed as a semi-conducting material. Different cases of shale samples (natural core, cracked core, and synthetic) and saturations (dry to fully saturated samples) with this contaminant were used. Electrical parameters (dielectric constant, conductivity, and impedance plane), for shale samples collected from Bani-Swef area, were measured. Therefore, samples (shale) were contaminated with oil at various contamination levels and concentrations to measure the electrical responses. These electrical measurements were performed at a frequency range starting from 1 mHz to 100 kHz. The results reveal that when levels of contamination increase, electrical conductivity and dielectric constant decrease for all sample cases. The contaminant reflects its insulator electrical characteristics. The laboratory measurements show reasonable results for natural and synthetic samples, while those for cracked samples exhibit abnormal behaviour, because the contaminant penetrates through the fractures and causes some distortion in the electrical readings. The electrical measurements show that it can be used as a preliminary screening step for monitoring soil contamination, particularly for oil seepage cases. It may offer a high-quality functional technique that is both cost-effective and non-invasive. This method may allow for a fast evaluation and assist as a massive environmental monitoring tool. This approach aligns with the sustainable development goals of Egypt vision 2023.