Automated Acquisition and Processing of Multichannel Complex Resistivity Data

Versteeg, Roelof; LaBrecque, Doug; Sharpe, Roger; Wu, Yuxin; Slater, Lee; Richardson, Alex; Rowe, Trevor

doi:10.4133/1.2923610

Cited by 1 publication

(1 citation statement)

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“…Digitized waveforms were stored in a relational database and the conductivity amplitude (|σ|) and phase shift (φ) calculated for each channel through an iterative waveform misfit fitting procedure (Versteeg et al, 2006). This procedure has an error of about 1 % for |σ|, and about 0.2 mrad for φ.…”

Section: Electrical Measurementsmentioning

confidence: 99%

Calcite precipitation dominates the electrical signatures of zero valent iron columns under simulated field conditions

Versteeg

Slater

et al. 2009

Journal of Contaminant Hydrology

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Calcium carbonate is a secondary mineral precipitate influencing zero valent iron (ZVI) barrier reactivity and hydraulic performance. We conducted column experiments to investigate electrical signatures resulting from concurrent CaCO 3 and iron oxides precipitation under simulated field geochemical conditions. We identified CaCO 3 as a major mineral phase throughout the columns, with magnetite present primarily close to the influent based on XRD analysis. Electrical measurements revealed decreases in conductivity and polarization of both columns, suggesting that electrically insulating CaCO 3 dominates the electrical response despite the presence of electrically conductive iron oxides. SEM/EDX imaging suggests that the electrical signal reflects the geometrical arrangement of the mineral phases. CaCO 3 forms insulating films on ZVI/magnetite surfaces, restricting charge transfer between the pore electrolyte and ZVI particles, as well as across interconnected ZVI particles. As surface reactivity also depends on the ability of the surface to engage in redox reactions via charge transfer, electrical measurements may provide a minimally invasive technology for monitoring reactivity loss due to CaCO 3 precipitation. Comparison between laboratory and field data shows consistent changes in electrical signatures due to iron corrosion and secondary mineral precipitation.

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Section: Electrical Measurementsmentioning

confidence: 99%