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back to 6. Results                6.1. Outdoor experiments                

6.1.2 Bioindication of soil pollutants

Initial growth differences, dependent on the contamination degree of the lysimeter pots soil gradually  disappear, thus indicating the stepwise decrease of soil TNT content during the dendroremediation. These results agree for all deciduous trees tested. With spruces the results remain non-uniform because of contamination inhomogeneities of the soils. Confirmation experiments in 1-m³-lysimeters, where the soils were more uniformly, however, show the same trends in bioindication as measured with deciduous trees in lysimeter pots.

The growth bioindication of the stepwise decrease of soil nitroaromatics is confirmed by yield measurements. The results were also confirmed by the time course of quantification of soil leaching. For all deciduous trees the "nitroaromatic load" is gradually decreasing while the dendroremediation phase is progressing.

Exceptionally, growth inhibition of highly polluted soil "SA4" is still continuing in all planted variants till the end of the experiments. This result does not agree with nitroaromatic soil pollution. Further analysis revealed that an additional boron contamination is responsible for this effect.