Geophysical and atmogeochemical methods revealing old LNAPL contamination history of sandy aquifers

During last years a series of papers was devoted to possibilities of geophysical methods in detecting long time residing LNAPL plumes in the granular sediments. Sauck (2000) developed a new conceptual geophysical model for this case taking into the account geochemical processes caused by the bacterial biodegradation of hydrocarbons. The existence of the low resistivity zone below the LNAPL plume is the only chance to estimate the extent of the plume by resistivity survey (multielectrode measurements, vertical electrodes) and ground penetrating radar. We combined the geophysical techniques with the soil vapour survey using the new method and instrumentation (ECOPROBE 5) based on the combination of total PID (photo ionisation detector) and selective IR (infra-red) analysers. The efficiency of this approach is documented on materials from an abandoned military area in the Cretaceous of Bohemia.