Induced polarization applied to biogeophysics: recent advances and future prospects

Abstract

This paper provides an update on the fast‐evolving field of the induced polarization method applied to biogeophysics. It emphasizes recent advances in the understanding of the induced polarization signals stemming from biological materials and their activity, points out new developments and applications, and identifies existing knowledge gaps. The focus of this review is on the application of induced polarization to study living organisms: soil microorganisms and plants (both roots and stems). We first discuss observed links between the induced polarization signal and microbial cell structure, activity and biofilm formation. We provide an up‐to‐date conceptual model of the electrical behaviour of the microbial cells and biofilms under the influence of an external electrical field. We also review the latest biogeophysical studies, including work on hydrocarbon biodegradation, contaminant sequestration, soil strengthening and peatland characterization. We then elaborate on the induced polarization signature of the plant‐root zone, relying on a conceptual model for the generation of biogeophysical signals from a plant‐root cell. First laboratory experiments show that single roots and root system are highly polarizable. They also present encouraging results for imaging root systems embedded in a medium, and gaining information on the mass density distribution, the structure or the physiological characteristics of root systems. In addition, we highlight the application of induced polarization to characterize wood and tree structures through tomography of the stem. Finally, we discuss up‐ and down‐scaling between laboratory and field studies, as well as joint interpretation of induced polarization and other environmental data. We emphasize the need for intermediate‐scale studies and the benefits of using induced polarization as a time‐lapse monitoring method. We conclude with the promising integration of induced polarization in interdisciplinary mechanistic models to better understand and quantify subsurface biogeochemical processes.

Sensing the electrical properties of roots: A review

“…Understanding of the root–soil–fluid interface from an electrochemical point of view and the inner root ionic distribution is necessary to properly interpret the overall signature when an external field is applied. More EIS and SIP studies at the root scale will help to improve the understanding of the main underlying mechanisms of polarization in roots, which is a requirement for the development of a phytophysical model (Kessouri et al., 2019) that links root electrical signatures to root properties and root activity.…”

“…It uses a broad range of frequencies from millihertz to tens of kilohertz and four electrodes to reduce the influence of contact resistances and to improve the accuracy of the complex impedance measurements (Zimmerman et al 2008). Spectral induced polarization has been successfully applied in various biogeophysical investigations (Abdel Aal, Atekwana, Slater, & Atekwana, 2004;Abdel Aal, Slater, & Atekwana, 2006;Atekwana & Slater, 2009;Atekwana, Werkema, & Atekwana, 2006;Kessouri et al, 2019). Mary et al (2017) studied isolated coarse roots (in the laboratory) and found that coarse roots showed higher resistivity and polarized differently compared with soil, suggesting that SIP is a promising tool for root studies.…”

“…The frequency‐dependent current paths through plant tissues, showing (b) low‐frequency current pathway and (c) high‐frequency current pathway. (d) Description of counterion polarization mechanism in root segments occurring at low frequencies (Kessouri et al., 2019; Weigand & Kemna, 2019). The strength of the electrical double layer (EDL) polarizability depends on the composition and concentration of ions in the extracellular fluid (ECF) and electric potential distribution at the cell membrane (Kinraide, 2001; Kinraide & Wang, 2010; Wang et al., 2011).…”

“…Instead, they can only cross the membranes through ion pumps and ion channels (see the Glossary) whose opening and closing are regulated by the potential difference across the membrane (voltage). Electrical charges at the surface of the cell membrane lead to the formation of an electrical double layer (EDL), consisting of a layer of surface charges of the cell membrane and a layer of associated counterions (Figure 1d) (Kessouri et al., 2019; Kinraide, 2001; Kinraide & Wang, 2010, Weigand & Kemna, 2019). When applying an alternating current, the polarization strength depends on frequency, intensity, and duration of the injection, surface charge density of the cell membrane, transmembrane potential difference, ionic concentration, water content, tissue composition, and tissue health or structural heterogeneity (Ackmann, 1993; Bera, Nagaraju, & Lubineau, 2016; Repo, Cao, Silvennoinen, & Ozier‐Lafontaine, 2012).…”

Preliminary assessment on the application of biochar and spectral‐induced polarization for wastewater treatment

“…; Kessouri et al . ). In biochar containing media, geophysical methods can be used to characterize biochar concentration and/or monitor biochar‐related processes.…”