Spectral induced polarization signature of soil contaminated by organic pollutant: Experiment and modeling

Abstract

[1] The spectral induced polarization (SIP) signature of soil contaminated with organic pollutant was studied. Using a flow column experiment, the effect of crystal violet (CV, a polar organic pollutant) on the temporal change of the SIP response over a broad frequency range (1 mHz to 45 KHz) was determined. Complimentary measurements were used to determine the effect of CV on the chemical composition of both the pore water and the solid surface. In addition, analysis of the experimental results was carried out by using both chemical complexation and induced polarization models. Our results shows that adsorption of CV to the mineral surface resulted in release of inorganic ions to the soil solution, increasing the solution electrical conductivity and therefore also the real part of the complex conductivity. Despite the increase in the real part of the complex conductivity, the imaginary part of the complex conductivity decreased with increasing concentration of adsorbed CV. Using the Revil induced polarization model, we were able to show that the contribution of the adsorbed CV to the polarization of the soil is negligible, and that the main process affecting the polarization is the decrease in the density of the inorganic surface species. The results of this study can be used to better interpret SIP signature of soils contaminated by organic compounds.

Complex conductivity of soils

“…The amplitude of resistivity and the phase can be recasted into a complex conductivity. Under an applied (primary) electrical field, its in-phase (real) component characterizes the electromigration of the charge carriers while its quadrature (out-of-phase, imaginary) component is used to describe local accumulations of electrical charge Induced polarization has many applications in hydrogeophysics including inference of hydraulic properties [Binley et al, 2005;Weller et al, 2010;Joseph et al, 2015;Nordsiek et al, 2015], facies discrimination , the detection of contaminants in soils [e.g., Sogade et al, 2006;Flores Orozco et al, 2012;Schwartz and Furman, 2012;Schmutz et al, 2012;Chen et al, 2013], and the detection of cracks [e.g., Okay et al, 2013]. Induced polarization has shown also a unique capability to monitor nonintrusively sorption processes in the electrical double layer [Vaudelet et al, 2011a[Vaudelet et al, , 2011bHao et al, 2016] and precipitation of metallic particles during redox-controlled reactions [e.g., Mewafy et al, 2013;Abdulsamad, 2017].…”

“…While much work has been done in describing the electrical conductivity of soils (see a review in Friedman [2005]), few publications have targeted the complex conductivity of these porous materials (see Schwartz and Furman [2012], Nordsiek et al [2015] for limited investigations with few core samples). In the present paper, we test the dynamic Stern layer model developed by Revil and collaborators to describe the complex conductivity of brinesaturated clayey soils.…”

“…Induced polarization has many applications in hydrogeophysics including inference of hydraulic properties (Binley et al [2005]; Weller et al [2010], Joseph et al [2015]; Nordsiek et al [2015]), facies discrimination , the detection of contaminants in soils (e.g., Sogade et al [2006], Flores Orozco et al [2012], Schwartz and Furman [2012], Schmutz et al [2012], Chen et al [2013]), and the detection of cracks (e.g., Okay et al [2013]). Induced polarization has shown also a unique capability to monitor non-intrusively sorption processes in the electrical double layer (Vaudelet et al [2011a, b], Hao et al [2016]) and precipitation of metallic particles during redox-controlled reactions (e.g., Mewafy et al 4 [2013], Abdulsamad [2017]).…”

The effect of free-phase NAPL on the spectral induced polarization signature of variably saturated soil

“…In their conceptual model, these inorganic ions are released to the pore water, and by that increasing their conductivity, while the organic ions are adsorbed to the mineral surfaces. Schwartz and Furman [] further investigate the effect of polar organic compounds on the SIP signature of soil. They were able to show that the decrease in the soil polarization is due to the low mobility of the adsorbed organic compounds on the soil mineral surface.…”

Theoretical Modeling of Dielectric Properties of Artificial Shales

“…In recent decades, shale dielectric modeling was mainly focused on the effects of the electrical double layer associated with clay minerals (e.g., [1][2][3][4][5][6][7]). Effort has been made to develop models that can explain the dependence of complex electrical conductivity on cation exchange capacity (CEC) and specific surface area (SSA), salinity and pH of the pore water, sorption of cations and organic molecules, influence of grain size, and the relationship between surface conductivity and quadrature conductivity, temperature, and water saturation.…”