Electrical resistivity tomography as monitoring tool for unsaturated zone transport: an example of preferential transport of deicing chemicals

Wehrer, Markus; Lissner, Heidi; Bloem, Elke; French, Helen K.; Totsche, Kai Uwe

doi:10.1007/s11356-013-2252-2

Cited by 13 publications

(12 citation statements)

References 55 publications

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“…This apparently less well fitted model is potentially due to the sand developing a water table and therefore contains two zones with different GMCs. But could equally be explained by the existence of low clay content soils possessing a discontinuous electrical double layer (Wehrer et al, 2014).…”

Section: Laboratory Experimentation and Modellingmentioning

confidence: 99%

Measurement and modelling of moisture—electrical resistivity relationship of fine-grained unsaturated soils and electrical anisotropy

Merritt

Chambers

Wilkinson

et al. 2016

Journal of Applied Geophysics

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A methodology for developing resistivity-moisture content relationships of materials associated with a clayey landslide is presented. Key elements of the methodology include sample selection and preparation, laboratory measurement of resistivity with changing moisture content, and the derivation of models describing the relationship between resistivity and moisture content.Laboratory resistivity measurements show that the techniques utilised (samples and square array) have considerable potential as a means of electropetrophysical calibration of engineering soils and weak rock.Experimental electrical resistivity results show a hierarchy of values dependent on sample lithology, with silty clay exhibiting the lowest resistivities, followed by siltstones and sands, which return the highest resistivities. In addition, finer grained samples show a greater degree of anisotropy between measurement orientations than coarser grained samples.However, suitability of results in light of issues such as sample cracking and electrical conduction must be identified and accounted for if the results are to be accurately up-scaled to inverted model resistivity results.The existence of directional anisotropy makes model calibration curve selection more difficult due to variability in the range of measured laboratory resistances.The use of larger measurement array size means that experimental data will be more representative of bulk lithological properties. In addition, use of electrodes with a relatively high surface area (wide diameter) help maintain low contact resistances and repeat measurement error, relative to narrow electrodes.Variation exists between the fit of experimental data and petrophysical models. Model fit is best for claydominated samples but fits less well for sand-dominated samples. Waxman-Smits equation is appropriately applied in this investigation as all samples have considerable clay mineral content, as is shown in nonnegligible CEC results. The incorporation of pressure plate suction measurements on samples, allows suction dissipation to be quantified and evaluated alongside moisture content and electrical resistivity.

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Section: Laboratory Experimentation and Modellingmentioning

confidence: 99%

Measurement and modelling of moisture—electrical resistivity relationship of fine-grained unsaturated soils and electrical anisotropy

Merritt

Chambers

Wilkinson

et al. 2016

Journal of Applied Geophysics

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“…Considerable development in the field of electrical resistivity tomography for the characterization of solute breakthroughs has occurred over the last 20 years [ Binley et al ., ; Day‐Lewis and Singha , ; French et al ., ; Garre et al ., ; Irving and Singha , ; Koestel et al ., ; Olsen et al ., ; Singha et al ., ; Slater et al ., ; Wehrer et al ., ; Wehrer and Slater , ]. The potential of ERT to visualize heterogeneous conservative transport was shown by cross‐borehole tomography [ Daily et al ., ], 2‐D imaging along a trench [ French et al ., ] and 3‐D imaging in lysimeters [ Binley et al ., ; Garre et al ., ; Koestel et al ., ; Olsen et al ., ; Wehrer et al ., ; Wehrer and Slater , ]. Temporal and spatial moments derived from time‐lapse images were validated for breakthroughs of conservative tracers [ French et al ., ; Koestel et al ., ; Wehrer and Slater , ] and show that quantitative information on transport processes can be extracted using this technique.…”

Section: Introductionmentioning

confidence: 99%

“…Temporal and spatial moments derived from time‐lapse images were validated for breakthroughs of conservative tracers [ French et al ., ; Koestel et al ., ; Wehrer and Slater , ] and show that quantitative information on transport processes can be extracted using this technique. Observation and validation of reactive tracer breakthroughs using ERT in the unsaturated zone are rare [ Wehrer et al ., ]. Observations of heterogeneous flow and transport done by ERT can be validated using dye tracer breakthroughs [ Binley et al ., ; Koestel et al ., ] or using a multicompartment sampler (MCS) [ Wehrer and Slater , ].…”

Section: Introductionmentioning

confidence: 99%

Characterization of reactive transport by 3-D electrical resistivity tomography (ERT) under unsaturated conditions

2016

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The leaching of nitrate from intensively used arable soil is of major concern in many countries. In this study, we show how time lapse electrical resistivity tomography (ERT) can be used to characterize spatially heterogeneous processes of ion production, consumption, and transport in soils. A controlled release fertilizer was introduced into an undisturbed soil core in a laboratory lysimeter and subjected to infiltration events. The production of ions resulting from processes associated with nitrification and their transport through the soil core was observed by time lapse ERT and analysis of seepage water samples from a multicompartment sampler. ERT images show development and propagation of a high‐conductivity plume from the fertilizer source zone. Molar amounts of nitrate produced in and exported from the soil core could be well reproduced by time lapse ERT using a spatial moment analysis. Furthermore, we observed that several shape measures of local breakthrough‐curves (BTCs) of seepage water conductivity and nitrate derived by effluent analyses and BTCs of bulk conductivity derived by ERT are highly correlated, indicating the preservation of spatial differences of the plume breakthrough in the ERT data. Also differences between nitrate breakthrough and a conservative tracer breakthrough can be observed by ERT. However, the estimation of target ion concentrations by ERT is error bound and the smoothing algorithm of the inversion masks spatial conductivity differences. This results in difficulties reproducing spatial differences of ion source functions and variances of travel times. Despite the observed limitations, we conclude that time lapse ERT can be qualitatively and quantitatively informative with respect to processes affecting the fate of nitrate in arable soils.

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“…Additionally, other techniques such as magnetic resonance imaging (MRI), neutron tomography (NT), positron emission tomography (PET), electrical resistivity tomography (ERT), and scanning electron microscopy (SEM) have also been used for soilroot-related investigations (Asseng et al 2000;Perret et al 2000;Tumlinson et al 2008;Nagel et al 2009;Carminati et al 2010;Marto et al 2014;Wehrer et al 2014). However, none of the above-mentioned individual methods is without limitations (Handschuh et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Combining X-ray computed tomography with relevant techniques for analyzing soil–root dynamics – an overview

Mao

Kumi

et al. 2015

Acta Agriculturae Scandinavica, Section B — Soil & Plant Sc

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The study of below-ground features of roots and soil and their interactions is essential for understanding the configuration and diversities in such a dynamic environment. X-ray computed tomography is recognized as a tool for visualizing the physical interactions in the soil. In many studies, it has been used as a stand-alone tool to describe soil and root parameters. However, in recent times, attempts to couple it with other complementary tools are gaining rapid interest among researchers. The paper therefore provides an overview of the major application of combining X-ray computed tomography with other relevant methods in analyzing the structural characteristics of roots and soil media. The relevance of using this multidisciplinary approach for unraveling the mysteries surrounding root-soil dynamic interactions is stressed. The current and future trends of such studies are also pointed out.

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Electrical resistivity tomography as monitoring tool for unsaturated zone transport: an example of preferential transport of deicing chemicals

Cited by 13 publications

References 55 publications

Measurement and modelling of moisture—electrical resistivity relationship of fine-grained unsaturated soils and electrical anisotropy

Measurement and modelling of moisture—electrical resistivity relationship of fine-grained unsaturated soils and electrical anisotropy

Characterization of reactive transport by 3-D electrical resistivity tomography (ERT) under unsaturated conditions

Combining X-ray computed tomography with relevant techniques for analyzing soil–root dynamics – an overview

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