Einsatz von mykorrhizierten Pflanzen in der Phytoremediation und ihr Einfluss auf Selbstreinigungsprozesse (Enhanced Natural Attenuation) in MKW-belasteten Böden

Abstract

The aim of the present work was to contribute useful information towards the development of phytoremediation as an ecological compatible and cost effective clean up strategy for contaminated soils. A key role in this context is played by the mycorrhizal symbiosis of soil-fungi and plant-roots, which stimulates the biodegradation of contaminants in their surrounding (mycorrhizosphere). For the experiments sand was spiked with a predefined PHC test-solution and Pinus sylvestris was selected as host plant. According to an initial batch test Suillus bovinus showed the highest PHC tolerance, while Rhizopogon roseolus was able to utilise PHC as a carbon source. The tolerant symbionts needed to demonstrate their ability to form a steady mycorrhiza under PHC conditions in Petri dish microcosms, and their sustainability in subsequent pot experiments. The results of these experiments revealed that extensive colonisation, which led to the most effective PHC remediation, could be achieved by systematic in-vitro mycorrhization. Rhizopogon roseolus vigorously enhanced plant growth under PHC stress and Suillus bovinus prevents the movement of contaminants. Mycorrhizal pine seedlings accelerated PHC removal by stimulating an effective PHC degrading community of microorganisms. Furthermore, among other effects, mycorrhizal plants improved control of the soil water balance by increasing transpiration and the oxygen supply of the soil. To upgrade the comparability of the results to field conditions the investigations were completed using large-scale lysimeter tests for the observation of important natural attenuation processes like volatilisation, translocation, sorption, degradation and leaching of contaminants as well as plant and fungal development, soil respiration, soil water balance, and further physical and chemical soil parameters. The results made obvious, that the application of appropriate plant-fungus-associations can critically affect the success of phytoremediation.