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(T/MF191) Biorremediation of contaminated soils with heavy metals by Miscanthus x giganteus - Some aspects of the environmental impact assessment. Fernando, Ana Luisa1, Santos-Oliveira, José Filipe1, 1 ABSTRACT- The use of energy crops must be studied in terms of the evaluation of their environmental impacts, in order to integrate them in a sustainable agriculture development, not only in Europe but in other regions where those crops are or could be cultivated. The main purpose of this work is to study some aspects of the ecological sustainability of the biorremediation of contaminated soils with heavy metals by Miscanthus x giganteus. In this context, four levels of contamination with domestic sludge were studied: P0 = 0 t, P50 = 50 t, P100 = 100 t, and P200 = 200 t.ha-1. According to the methodology applied, the utilisation of Miscanthus x giganteus for the bioremediation of soils contaminated with heavy metals showed positive environmental aspects. The net energy gain obtained is high, indicating that Miscanthus is a good alternative source of renewable energy and that a significant amount of fossil energy could be saved. The net amount of avoided emissions of greenhouse and acidifying gases was also positive, contributing to the reduction of global warming and acid rain. In what concerns the N, P and K emissions to soil and water, they are dependent on region and crop management. For each local, better values could be obtained if fertilisers were applied in balanced amounts. In terms of erosion, the highest risks occur before growth, during winter, when there is a lack of soil cover and when the rainfall is more severe. Overall, contaminated fields presented better ecological balances than the non-contaminated ones, specially due to the highest productivities observed. Uptake of heavy metals by Miscanthus in the polluted fields was of potential concern, specially if the combustion of the crop may give rise to ashes with unacceptable levels of heavy metals. Concerning the several metals determined on aerial biomass, no significative differences were verified among the different levels of contamination. Key words: miscanthus, contaminated land, domestic sludge |
