Das Projekt "Massenbilanz fuer die Planung und Steuerung der sanften Sanierung und anschliessenden nachhaltigen Nutzung kontaminierter landwirtschafticher Boeden" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Terrestrische Ökologie, Fachbereich Bodenschutz durchgeführt. Gentle remediation of agricultural soils by extraction of polluting heavy metals through accumulator plants is an emerging technique which has the advantage that soil fertility is restored, while it is sacrificed for the goal of detoxification by other techniques such as soil excavation, washing, incineration or metal extraction by strong acids. The disadvantage is that the process is rather slow. The planning of such remediation operations thus demands for a careful assessment of the required time. For this purpose mass flux balances must be sufficiently accurate. In this project the method PROTERRA, which was previously developed for establishing regional mass flux balances of heavy metals in agricultural land, was adapted for application in planning and monitoring gentle soil remediations in the framework of sustainable land use. The main scientific objectives were (i) to develop adequate methods for quantifying the reliability and the accuracy of such mass balances and (ii) to integrate gentle soil remediation operations into a regional soil monitoring concept. For these tasks we extended PROTERRA by a stochastic module evaluating and propagating probability distributions of parameters to account for their uncertainty. The new model, PROTERRA-S, estimates cadmium-, zinc- and copper flux balances for regions of about 100 km2 and quantifies the contribution of uncertain parameters to the total variance of the net-metal fluxes using uncertainty analysis. The model results are calculated in two steps: (i) metal flux balances for land-use classes within the region (stratified by cropping system and farm type) and (ii) metal flux balances on regional scale, which indicate an average metal flux balance. We applied the model to a testregion Sundgau, Cantons BL and SO, of about 95 km2. The mass flux balances of the land-use classes can be used to assess subsequent agricultural land use of sites, that were remediated by metal-accumulating plants. To sum up, PROTERRA-S is a transparent scientific tool for taking suitable measures in order to prevent metal accumulation in agricultural soils including uncertainties of metal flux balances.
Das Projekt "Biologische Dekontamination schwermetallbelasteter Boeden mit Hyperakkumulatoren: Beeinflussung der Schwermetallaufnahme im Wurzelraum" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich (ETHZ), Institut für Terrestrische Ökologie ITOE durchgeführt. Remediation of heavy-metal polluted agricultural soils requires gentle methods, i.e. methods by which the fertility of the soil is fully restored. This means that harsh methods such extraction of metal pollutants by strong acids or soil washing are not applicable as they do not only remove the pollutants, but also destroy the physical and chemical basis of soil fertility, e.g. soil structure and cation exchangers, as well. Soil cleaning by methal harvesting through accumulator plants is a promising technique for the gentle remediation of heavy metal contaminated soils. Up to now one major problem of this technique has been however the comparatively low productivity of candidate accumulator plants under field conditions. In this project we investigate possibilities to improve the efficiency of this method by enhancing the availability of the pollutants for the roots of the accumulator plants, i.e. by applying mobilizing additives such as chelator agents or by optimizing root growth through classical agricultural techniques such as soil preparation, fertilization and harvesting regimes. Leading Questions: Can metal-accumulating plants be used to clean-up heavy-metal polluted calcareous soils for agricultural or similar re-use?
Das Projekt "Stoffflussbilanzierung als Planungs- und Kontrollinstrument bei der (sanften) Sanierung und nachhaltigen Folgenutzung von schadstoffbelasteten Kulturboeden" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich (ETHZ), Institut für Terrestrische Ökologie ITOE durchgeführt. Mass flux balancing is a fundamental method for the management and control of transport and transformation processes. Gentle remediation of agricultural soils by extraction of polluting heavy metals through accumulator plants is an emerging technique which has the advantage that soil fertility is restored, while it is sacrificed for the goal of detoxification by other techniques such as soil excavation, washing, incineration or metal extraction by strong acids. The disadvantage is that the process is rather slow. The planning of such remediation operations thus demands for a careful assessment of the required time. For this purpose mass flux balances must be sufficiently accurate. Furthermore mass flux balancing may also be used for controlling the long-term success of the remediation which can be expected in terms of the sustainability of subsequent land use. In this project the method PROTERRA which was previously developed for establishing regional mass flux balances of heavy metals in agricultural land is adapted for these purposes. Sources and propagation of sampling errors are investigated, in particular the effects of spatial variability on the accuracy of the mass balancing and the problem of combining data relating to different spatial and temporal scales. Leading Questions: Develop methods for quantification of the reliability and accuracy in mass flux balances.
Das Projekt "Biologische Sanierung schwermetallverseuchter Boeden unter Verwendung hyperakkumulierender Pflanzen: Beeinflussung der Aufnahme von Schwermetallen im Wurzelbereich" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Terrestrische Ökologie, Fachbereich Bodenschutz durchgeführt. Remediation of heavy-metal polluted agricultural soils requires gentle methods, i.e. methods by which the fertility of the soil is fully restored. This means that harsh methods such as the extraction of metals by strong acids or soil washing are not applicable as they do not only remove the pollutants, but also destroy the physical and chemical basis of soil fertility, e.g. soil structure and cation exchange sites. As soil cleaning by metal harvesting through accumulator plants had shown to be a promising, but not yet sufficiently effective technique for the gentle remediation of heavy metal contaminated soils, we investigated possibilities to increase the efficiency of phytoextraction by enhancing the phytoavailability of the metals cadmium, zinc and copper for various metal-polluted agricultural soils of Switzerland. We focussed on two innovative approaches. In the first approach we evaluated the possibility to enhance metal phytoavailability by the addition of elemental sulphur to the soil. The other approach started out from the completely innovative idea to exploit natural siderophores as agents to enhance metal availability. Elemental sulphur application was very effective in solubilizing Zn and Cd in calcareous soil and even more in acidic soil. Unfortunately, however, the effect on plant uptake was much weaker than on the solubility of the metals in the soil. Still, metal uptake in plants grown on calcareous soil under field conditions was increased up a factor of 8. Additional field trials performed at other locations in Switzerland showed that the conditions at Dornach were particularly difficult for phytoremediation. At the current state-of-the-art, clean-up of metal-polluted soils by phytoextraction would require still several decades also the other investigated sites, however. The siderophore studies were performed with model systems consisting of soil mineral suspensions, addressing the lack of a fundamental study of the interactions between siderophore, metals and soil constituents. Desferrioxamine B (DFOB) was used as a model siderophore. For comparison, analogous experiments were performed with citrate and NTA. The results show that the effect of such ligands can be mobilizing as well as immobilizing, depending on soil conditions. While the effects in the model system could be under-stood in terms of chemical speciation modelling, it was found that they did not fully explain the effects observed with field soil samples, suggesting that the model system did not fully represent the dominant features of the real soil. However, the experiments opened up new perspectives for the use of siderophores worth to be further investigated.