Der Einsatz von mykorrhizierten Feuchtgebietspflanzen in Bodenfiltern zur Reinigung von Oberflächenabwässern

Abstract

Use of mycorrhizal wetland plants to improve constructed wetlands for decentralised treatment of surface runoff was studied in several pilot experiments. Selected helophytes, grown in a suitable filter substrate, were inoculated with arbuscular mycorrhizal fungi (AMF) and treated with pollutants detected in surface runoff. Tested pollutants were: heavy metals (copper, zinc), petroleum hydrocarbons (C12, C15, C20), monoaromatics (toluene, cyclohexane), fuel additive MTBE, PAHs (acenaphthene, phenanthrene) and herbicide 2,4-D. Effect of de-icing salt was also tested. Purple loosestrife (Lythrum salicaria) was chosen for extensive investigations. Experimental data showed that planting improved significantly the efficacy of treatment. Negative influence on plant vigour and percentage of root colonisation was only demonstrated for heavy metals and salt. Mycorrhiza increased resistance of plants and reduced uptake of heavy metals. Eluviation of Copper was little and was further reduced by planting. Studies on depletion of petroleum hydrocarbons and PAHs result no differences between mycorrhizal and non-mycorrhizal variants, but positive effect of planting was proven. AMF-colonisation was not inhibeted by waterlogging and improved plant vigour and production of biomass. Although the retention capacity of AMF for heavy metals and influence of mycorrhization on depletion of organic pollutants could not be fully elucidated in this work, the use of mycorrhizal wetland plants to improve the cleaning capacity of constructed wetlands is recommended because of their positive effect on plant vigour and biomass formation.