Soil and groundwater contamination has been widely concerned because of its impact on industrial, agricultural production, and even human health. Accurate delineation and monitoring of contaminants are the basis for successful remediation strategies. Traditional drilling-based methods are costly and less efficient. Geophysical methods, particularly electrical resistivity (ERT) and induced polarization (IP), are sensitive to soil and groundwater contamination and have been proven very effective. However, there were still some pressing issues to be resolved, such as reliable interpretation of IP parameters for contaminants characterization and monitoring of dynamic processes.

Aiming for successful detection, we established the relationship between concentrations and IP parameters according to laboratory column experiments. The IP data acquisition method were improved for field surveys, significantly increasing the IP data quality. In addition, we propose a refined structure-constrained method that updates the smooth weights using three different magnitudes. With the joint interpretation of multisource data, the accuracy was improved and therefore the number of sampling boreholes was reduced.

So far, we have successfully applied ERT and IP techniques to delineate more than 20 contaminated sites. To understand the complex system of contaminant remediation, we quantified the effect of contaminant removal on IP parameters. IP measurements in combination with hydrochemical information clearly enables the characterization of remediation dynamics and facilitates the pore structure recognition based on IP conceptual models.

Moreover, we investigate the IP response of zero valent iron, activated carbon and sand mixtures to monitor the long-term performance of the permeable reactive barriers. We reveal the dependence of IP parameters on the volume content, surface area, and particle size of the reactive particles, as well as on the pore water conductivity.

A 720-hour monitoring experiment for NO₃ – contamination remediation yielded that the normalized chargeability and  relaxation time are sensitive to changes of surface area and particle size. In conclusion, we have shown that geoelectrical methods, represented by ERT and IP, have significant potentials on characterization and monitoring of contaminated subsurface.

Prof. Deqiang Mao, School of Civil Engineering, Shandong University, Jinan, China.

Lieu
Laboratoire METIS, Sorbonne Université, Campus Pierre et Marie Curie
4, place Jussieu 75005 Paris
Salle Darcy, tour 46-56, 3^e étage.

• 10:30 to 11:00 – Welcome and coffee at METIS
• 11:00 – Presentation of the IMAGE Project by Philippe Leroy
• 11:30 – Presentation of Noura Eddaoui
• 12:00 – Invited seminar « Characterization and monitoring of contaminated subsurface using geoelectrical methods » by Prof. Deqiang Mao

Presentations will be available remotely through the zoom link below:
Zoom : Workshop Geophysics in contaminated area
Heure: 12 avr. 2024 10:00 AM Paris

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https://cnrs.zoom.us/j/98244484378?pwd=aWhPZWU5ZmxhaTAxTjdjSWt1WlExZz09

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