Summary
As a legacy of the Third Reich, sites contaminated by the explosive 2,4,6-trinitrotoluene (TNT) and associated materials pose a threat through the leaching action of groundwater, or these substances may already be encountered as contaminants in aquifers. Physico-technical soil decontamination processes are generally applied ex situ. In consequence, these processes are highly cost-intensive, and will only be suitable for the decontamination of highly-polluted sites in individual cases.
In the search for affordable and socially acceptable options for soil decontamination, the development of biological decontamination technologies for soil protection has progressed – these methods also recommend themselves on economic grounds. The main objective of these investigations was the analysis of the phytoremediation potential of trees for compounds typically contained in explosives (dendromediation).
Dendromediation has been confirmed under outdoor conditions in all the woodlands tested, using bioindicators for growth and the chemical monitoring of leachate.
Results:
- In deciduous and coniferous woodland, it has been possible to demonstrate the complete incorporation of [14C]-TNT or the metabolising of TNT to produce hitherto unknown metabolites, together with differentiation in the compartmentalisation of residual [14C]-TNT in mature woodlands.
- By a combination of results for:
- dendro-tolerance experiments,
- radiotracer investigations and
- measurements of yields in outdoor plots
it has been possible to calculate the dendroremediation potential of new woodland plantations, together with the progress of natural attenuation in existing contaminated woodland sites. It has also been possible to formulate specific decontamination recommendations and specific options for the promotion of natural attenuation in contaminated sites.
