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Dissolved Contaminant Plume Characterization through ERT, Geochemical Monitoring and Laboratory Measurements
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, Near Surface Geoscience 2012 – 18th European Meeting of Environmental and Engineering Geophysics, Sep 2012, cp-306-00124
- ISBN: 978-90-73834-34-7
Abstract
eakage is present on a gas station. A geophysical and geochemical study have been realized to find out in what proportion the changes of electrical properties induced by the dissolved plume may be linked to chemical variations. From a geoelectrical point of view, hydrocarbons plumes may be partially compared to saline ones increasing fluid mineralization. Therefore, electrolytic conduction may not be the only path of electrical conductivity; surface conductivity can also be modified by contamination and cause an increase of the global conductivity. A fixed acquisition system using electrical resistivity tomography has been installed. To monitor the spatial and temporal evolution of the contaminant plume, the resistivity values have been corrected from the temperature effect. The Archie’s law have been used to calculate the pore fluid resistivity which has been linked to groundwater chemical analysis. Laboratory measurements, specifically spectral induced polarization and temporal induced polarization have also been performed. The results have been compared to in situ and laboratory analysis. Hydrocarbons as aliphatic molecules in dissolved phase seems less to be at the origin of the geophysical response in particular in clay-free medium, as their byproducts.