Advances in time-domain induced polarization monitoring with application on chlorinated solvents contamination : Towards scalable real-time geophysical monitoring

Abstract: Environmental pollution is a significant concern for scientists, practitioners, authorities and the society. Among the various pollutants, chlorinated solvents pose a considerable risk to our groundwater resources. These hazardous chemicals, often used in industrial processes, can contaminate soil and water, posing a threat to both human health and ecosystems. Detecting and tracking the spread of these contaminants is crucial to prevent further damage and facilitate remediation efforts.The research focuses on developing and refining a technique called direct current resistivity and time-domain induced polarization (DCIP) monitoring, which is a geophysical method to measure the electrical properties of subsurface materials. The method can provide images of the subsurface, like medical imaging, showing the change of the electrical properties over time. By tracking those changes researchers can monitor dynamic processes in the ground. The focus of the study is to use the methodology to follow changes that happen in the ground following an in-situ bioremediation treatment of a site contaminated with chlorinated solvents.The research shows that the joint use of geophysical and hydrochemical data enhances the overall understanding of in-situ remediation processes and indicates that the ongoing remediation is successfully reducing the concentration of contaminants in the ground. While geophysical imaging can potentially provide qualitative answers in areas where it is challenging to collect water samples, follow-up mostly relies on groundwater sampling to delineate information regarding the concentration of contaminants. Furthermore, the study highlights the importance of considering seasonal variations in data interpretation, as well as the need for consistent water sampling during the same period. Geophysical imaging offers insights into the spreading of injected fluids, while groundwater chemistry data is crucial for a qualitative analysis of contaminants in the water. Together, these methods complement each other to better understand the changes occurring during in-situ remediation experiments. Also, the study demonstrates the importance of using a multimethod geophysical approach together with auxiliary data to update existing geological models and improve the understanding regarding the subsurface conditions prior to a monitoring experiment.In the rapidly evolving field of geoelectrical monitoring, managing and interpreting large volumes of data is a constant challenge. The research study presents an efficient methodology that simplifies the process of collecting, processing, and displaying geoelectrical monitoring data, making it more accessible and user-friendly for experts and stakeholders alike. One of the most interesting aspects of this research is its scalability. The newly developed methods can be readily applied to small- and large-scale monitoring projects, making it a cost-effective and practical solution for environmental protection agencies and industries alike. With the ability to track in-situ bioremediation experiments in real-time, authorities can respond more quickly to mitigate the spread of pollutants, saving precious time and resources in the process. Furthermore, the research shows great potential in other geophysical monitoring applications.