Autor: Dipl.-Geoökol. Heidi Lißner
Soil Contamination: Advanced integrated characterisation and time-lapse Monitoring
The focus of the EU funded project SoilCAM is the non-invasive monitoring of degradable contaminants in soils and groundwater at two field sites characterised by different contamination types and geological heterogeneities. The project aims to improve current methods for monitoring contaminant distribution and biodegradation in the subsurface. Detailed bio-geo-chemical characterisation of the soils at two selected field sites are therefore used as an important input for interpretation of geophysical time-lapse measurements (ground-truthing). Our project partners are: BIOFORSK (Dr. H.K. French), AMRA (Prof. Dr. G. Greco), POLITO (Prof. Dr. A. Godio), WU SEG (Prof. Dr. S.E.A.T.M. van der Zee), ICIM (Dr. T. Ghinda), RISSAC (Prof. Dr. Biro), UMS (G. von Unold) and Iris Instruments (J. Bernard).
My PhD reseach, within the SoilCAM project framework, deals with monitoring reactive transport and biodegradation of deicing chemicals in column and lysimeter experiments for temporal ground-truthing and parameterization of models.
The lysimeter experiments are conducted next to the Gardermoen airport (OSL) in Norway. Large amounts of de-icing chemicals are spread for removal of snow and ice every winter since the opening of Norway's main airport in 1998 (for airplanes propylene glycol and for runways potassium formate). Thus, environmental effects of these chemicals are a major concern, because the airport is situated on Norway's largest unconfined rain-fed aquifer. Gardermoen is representative for contaminated sites where easily degradable and highly mobile contaminants are released to the soil. This project aims to study the fate of de-icing compounds and their metabolites in order to evaluate the potential of the unsaturated zone to buffer high loads of contaminants during snow melt. A further potential focus - in fact one focus of SoilCAM project itself - is the use of ERT (electrical resistivity tomography) to monitor contaminant transport and biodegradation in the unsaturated zone.
Unsaturated column experiments are carried out in order to simulate the conditions of the OSL site and to asses the mechanisms influencing contaminant transport processes. Soil cores are subjected to a variation of extreme single events (e.g. freezing-thawing cycles, drying-rewetting cycles, high intensity rain events) that are known to have a strong effect on contaminant release, transport, and degradation. Beside the detection of soil-effluent characteristics, additional measurements will be investigated that include the monitoring of CO¬2 as a result of microbial activity. Another challenge comprises electrical resistivity measurements on a small scale to trace the effect of certain parameters (e.g. water content and temperature) on changes in soil electrical conductivity. Further, the results may serve for interpretation of electrical resistivity measurements in the field.