Field demonstrations of phytoremediation options in the EU FP7 greenland network of trace element-contaminated sites
Résumé
Performances of the most promising gentle remediation options (GRO) for trace elementcontaminated soils (TECS), i.e. (aided) phytostabilisation, phytoextraction, and in situ stabilization/phytoexclusion, are assessed in a European network of 14 large field trials, within the EU FP7 GREENLAND project (http://www.greenland-project.eu/). The GRO efficiency is evaluated regarding various (a)biotic stresses, climatic conditions, pollutant linkages, (phyto)remediation strategies and sustainable land management. Investigated field sites cover a range of contamination scenarios (e.g. agricultural soils contaminated by dust fallout, sludged soils, mine tailings, landfills, dredged sediments, and post-industrial soils). Harmonized datasets are built up on metal(loid) exposure, plant parameters and yields (notably for plant parts converted into feedstock), mineral and biochemical composition of plant parts, ecosystem services, financial return and costs. Soils are sampled to monitor changes in metal(loid) exposure (e.g. labile contaminant pools), transfer to environmental compartments and bioaccessibility, ecotoxicological risks, and soil (multi)functionality and biodiversity. Transfer and bioconcentration factors, shoot metal(loid) removal, contaminant fluxes, and tolerance indices are computed. Dose (exposure) – plant response relationships are modelled. Data are summarized for various plant covers including poplar and willow short rotation coppices, annual crops of secondary metal accumulators (sunflower and tobacco), and metal-excluders (e.g. perennial grasses, barley and maize cultivars). The long-term efficiency and sustainability of GRO, progresses in remediation objectives (in compliance with national and best procedures), timescale management, maintenance, uncertainty and limitations (including spatial variation of contaminants, water requirements, global changes, etc.), potential flexibility and deployment at other sites are discussed as well as new deployed GRO and cultural practices (e.g. bioaugmentation).