Delineation of hydrocarbon contaminants with multi-frequency complex conductivity imaging

• Published in: The Science of the total environment 2021-05, Vol.768, p.144997-144997, Article 144997
• Main Authors: Flores Orozco, Adrián, Ciampi, Paolo, Katona, Timea, Censini, Matteo, Papini, Marco Petrangeli, Deidda, Gian Piero, Cassiani, Giorgio
• Format: Article
• Language: English
• Subjects: Hydrocarbon contamination; Jet fuel; Near surface geophysics; Noninvasive methods
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.144997

The characterization of contaminated sites is a serious issue that requires a number of techniques to be deployed in the field to reconstruct the geometry, hydraulic properties and state of contamination of the shallow subsurface, often at the hundreds of meter scale with metric resolution. Among the techniques that have been proposed to complement direct investigations (composed of drilling, sampling, and laboratory characterization) are geophysical methods, which can provide extensive spatial coverage both laterally and at depth with the required resolution. However, geophysical methods only measure physical properties that are indirectly related to contamination, and their correlation may be difficult to ascertain without direct ground truth. In this study, we present a successful example where the results of complex conductivity measurements conducted in an imaging framework are compared with direct evidence of subsoil contamination at a jet fuel impacted site. Thus, proving that a combination of direct and indirect investigations can be successfully used to image a site in its complex (potentially 3D) structure in order to build a reliable conceptual model of the site. [Display omitted] •Interpretation of 1D laser-induced fluorescence logs and complex electrical imaging•Imaging trapped fuel in the subsurface through 2D complex conductivity and 1D LIF•Geophysical electrical imaging and borehole methods to investigate a jet fuel spill•Interpretation of electrical anomalies related to geology and LNAPLs•IP increases in dissolved plume and negligible in free-phase LNAPLs.