Description succincte
(Anglais)
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The project aims to model the speciation, transport, leaching and bioavailability of heavy metals during phytostabilization with trees. The basis of this project is the vast amount of data collected during a model-ecosystem experiment with a young forest ecosystem established on a metal-polluted soils.
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Partenaires et organisations internationales
(Anglais)
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A, B, BG, HR, CY, CZ, DK, FIN, D, GR, H, I, IRL, MT, NL, N, SK, E, CH, GB
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Résumé des résultats (Abstract)
(Anglais)
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Phytostabilization is a possible remediation strategy for heavy metal polluted soils. In this project, we aim to integrate soil-related results from a large lysimeter study designed to evaluate phytostabilization of a heavy metal contaminated agricultural topsoil by afforestation. The basic data that have been used are changes in solid phase metal speciation and availability, water household measurements (e.g. evapotranspiration), root distribution, microbial biomass and activity, and soil solution composition (heavy metals, DOC and nutrients). Elevated heavy metal concentrations in the soil solution mainly affected the community structure of microorganisms and lead to a reduction in root growth. This not only influenced the degradation of soil organic matter and the formation of DOC, but, as a consequence, also the speciation and solubility of metals. A Phytoremediation Decision Support System (Phyto-DSS) was used to integrate environmental and plant data to provide a rapid assessment of the feasibility of phytoremediation, or in this case, phytostabilisation, as an appropriate management practice across various scenarios. The Phyto-DSS builds on the conceptual model of metal fluxes in the system to provide a whole system simulator, designed to provide information at the site level. The Phyto-DSS calculates daily plant water-use, plant metal uptake, leaching and the cost-benefit of the operation. We used the Phyto-DSS to calculate the performance of poplar, willow and spruce for the phytostabilisation of a contaminated soil near the city of Zürich. Modelling calculations reveal that spruce is the most effective species for phytostabilisation because it contemporaneously stabilises the soil physically, while only taking up limited amounts of contaminants. Poplar and willow, while having a high water use and growth rate, accumulate inordinate amounts of Cd in the leaves, thus providing an exposure pathway for this toxic element to enter the food chain. The advantage of the Phyto-DSS model is that the behaviour of the soil-plant system can be extrapolated into the future, thus reducing the need for lengthy experiments.
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