Substrati artificiali per gli interventi di ripristinoudambientale in aree contaminate da metalli pesanti

摘要

Mining activities can have a large local impact on the environment, in particular for the soils the problems are toxicity, high concentrations of heavy metals and low concentrations of nutrients and they are the cause of the difficulty in the development of plant species in these areas. In order to perform an environmental restoration, in these areas it is necessary to intervene on the ground by means of the substrates that are able to support the development of the vegetation (Tordoff et al., 2000).udIn mining areas it is necessary to intervene with the substrates to enhance growth of vegetation (Tordoff et al., 2000).udIn Sardinia, the mining activity has caused big changes of the territory with consequent problems of degradation and environmental impact. The problem of management of industrial structures and of the enormous amount of deposits of potentially polluting materials are created by the cessation of mining activities (Bacchetta et al., 2007).udThe purpose of this work is to study the development of methodologies, using a technical-scientific approach to use man-made substrates in environmental restoration in areas contaminated by heavy metals. This objective was pursued through the study of different man-made substrates, obtained by mixing different percentages of contaminated soil with dedicated substrates. The dedicated substrates were obtained by mixing different raw materials according to specific proportions.udThe considered disused mining area is that of Montevecchio, western Sardinia, in the area of Sulcis-Iglesias-Guspinese, identified as the site of reclamation of national interest (DM 468/01) and bounded by Decree of the Ministry of Environment and Protection of Land and Sea of 12 March 2003 (Plan Reclamation of disused mining areas of Sulcis-Iglesias-Guspinese, 2008).udThe contaminated soil was collected from the tailings pond in the mine of Montevecchio. After an analysis of previous studies and a careful bibliographic search, it was decided to use like plant species: Artemisia arborescens L. (Fam. Asteraceae), a native plant and colonizing plant; the Nerium oleander, a perennial plant that can be sampled throughout the year and the Populus Nigra L. Italica, a fast-growing species with a percentage of rooting for vegetative reproduction of 65%.udAll individuals of the populations used in the experiment were obtained through the taking of clones from mother plants growned in the wild. Subsequently the selected plants were propagated by agamic reproduction, through cuttings. The cuttings were grown in the greenhouse in plateaux and after rooting, were transplanted into pots, previously filled with the man-made substrate. The clones were placed in the greenhouse, in conditions of controlled temperature and humidity and regularly irrigated by drip. Weekly have been verified the plant health condition and the growth of the aerialudpart by detecting heights of plants by measuring the distance between the plane of the edge of the pot and the apical part of the plant.udFor each man-made substrate it was determined the content of C, H and N, pH, CSC, EC, the content of heavy metals and nutrients. The efficiency of the substrates were determined by the development of the growth curves, obtained by the mean value of the parameter biometric height.udBy the comparison between the curves it was possible to measure the influence of the genetic variability on the growth of different clonal populations planted in the same substrate and the influence of different substrate on the same clonal population.