Tetra- and trichloroethenes (PCE and TCE) are frequent groundwater contaminants at >18000 risk-classified contaminated sites in Sweden. The scale of this problem calls for improved site assessment and monitoring to efficiently prioritize direct efforts for remediation. Identification and quantification of in situ degradation (a.k.a. natural attenuation) is of particular interest to avoid more micro-ecologically damaging and costly remediation methods such as excavation and physical treatments. Conventional techniques are insufficient; contaminant spatial distribution may not be adequately mapped; mass balances are seldom closed; identification of key processes is elusive.

 

We aim to establish the synthesis of two novel techniques for field monitoring of the contaminants: Compound-Specific Isotope Analysis (CSIA) combined with geoelectrical imaging by Direct Current Induced Polarization (DCIP). CSIA provides the degradation status and ongoing degradation mechanism, and also serves to calibrate the DCIP interpretation.The non-invasive DCIP maps the electrical properties of soil, groundwater and contaminants to produce a spatial picture of the contaminant plume.

 

We are applying our concept to a PCE/TCE-contaminated site through coupled field and laboratory studies. Field and laboratory measurements and experiments are ongoing based on investigations at a field site in Kristianstad, southern Sweden. A project contact group of governmental problem owners (SGU; Swedish EPA) and practitioners (SGI; analytical and environmental consultants) ensures relevance and knowledge transfer to practitioners.