Comparison of electrical resistivity and extraction Soxhlet measurements to evaluate rehabilitation of polluted soil by hydrocarbon using electro-phytoremediation with Zea mays

Abstract

Fuel theft causes hydrocarbons to be dumped on the ground by altering the tubes through which they are transported; this negatively affects the soil quality around them. Geoelectrical studies, such as resistivity studies, propose a practical and rapid technique for detecting plumes due to organic contaminants compared to laboratory chemical studies. The present work evaluated the efficiency of the electrical resistivity measurement in follow-up remediation of soil contaminated with hydrocarbons due to fuel theft actions by comparing the results obtained with those observed in the Soxhlet chemical extraction test. The treatment was carried out using electro-phytoremediation as an environmental technique in a Leptosol, with the removal of 40 % of the hydrocarbon achieved during 55 days of treatment. Performing a statistical analysis, a positive correlation coefficient greater than 0.70 was determined in all soil samples studied. This corroborated the high relationship between the electrical resistivity variables and the mass of hydrocarbons g⁻¹ of soil, maintaining that the soil resistivity values increase in the presence of hydrocarbon from a recent spill, which generated hydrophobicity and blocking of porous, in consequence, reduction of the ionic conduction and cationic exchange capacity of soil by the aggregation of particles. In addition to the geophysical and chemical tests, physicochemical and microbiological studies were used to support the behavior of electrical resistivity and the presence of hydrocarbon in the soil samples before and after applying electro-phytoremediation.