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5D + E - Risk communication + From risk mgnt to sust. mgnt? (MOP/189) Phytostabilisation of heavy metal contaminated soils: a sustainable option for land management? Urzelai, Arantzazu1, Ciprian, Estela1, González, Miriam1, Cagigal, Ekain1, Bonilla, Alberto1, 1 LABEIN, Bilbao, Bizkaia, Spain ABSTRACT- Phytoremediation is an environmentally friendly technology based on the use of higher plants for the cleanup of contaminated soil and water. Fundamental and applied research has demonstrated that selected plant species possess the potential to remove, degrade, metabolise, or immobilise a wide range of contaminants. However, the process is slow and in the case of techniques such as phytostabilisation contaminants are still present (are not extracted), although in a less harmful form. These questions can prevent the use of phytoremediation as a real option in the redevelopment of contaminated areas, even as a medium-term option. In this paper we study the distribution of metals within the soil-water-plant system as well as the potential environmental impacts and risks associated to the presence of different forms of contaminants. The assessment is based on the results obtained in a phytostabilisation project of soils contaminated with heavy metals, which included different grasses and tree species as well as two different soil treatments. Impact assessment was based on risk assessment methodologies and on data on plant growth and metal uptake, loss of metals through leaching, availability of metals in soil solution and soil decontamination rate. The addition of metal immobilising agents to the soil decreases the absorption of metals by herbaceous species, and therefore reduces their incorporation to the food-chain. The establishment of a permanent vegetation cover has a positive effect in the reduction of metal losses through leaching, because it reduces the amount of leahates, thus minimising risks of groundwater contamination. For other targets and exposure pathways risk reduction is not significant. Results are discussed from the point of view of sustainability. Key words: risk assessment, phytostabilisation, land management, heavy metals |
