La presenza naturale ed antropica di metalli e metalloidi nei terreni e nelle acque della successione umbro-marchigiana. Studio ecologico della Bassa Vallesina

This PhD thesis concerns an ecological study aimed at identifying the natural and anthropogenic presence of the main metals / metalloids in the environment, together with an assessment of the risk related to their presence in environmental receptors. All these aspects, also in relation to the limit values set by the national and community regulations in force, have been contextualised in an ecological study of the Low Esino Valley (Marche, Italy). The research carried out shows a substantial concordance between the literature data and the natural background values for the soil and groundwater environmental matrixes, determined in an area adjacent to the study area with similar geological peculiarities. Concentrations exceeding the national regulatory limit values, were mainly found in groundwater (species for Fe, Mn, Pb and in the alternative Al, Zn and As) and inorganic salts (Chlorides, Sulphates). These geochemical anomalies are found in correspondence and/or proximity of certain geological formations (clays, evaporitic rocks), in intensely tectonized zones or in areas close to overhangs and in ephemeral aquifers characterized by low oxygenation and high content of organic matter. The Low Esino Valley, choice both for geological contiguity with the areas used for the study of the natural background, and for the extensive anthropization, has been the subject of a census of anthropic activities of potential contribution of metals through one of the indicators proposed by the European Environmental Agency (EEA). The processing of ERA (Ecological Risk Assessments) in the investigated area has shown a potential risk of minimal adverse effects in the environment, prevalently for aquatic organisms by As, Total Cr, Hg, Ni, Pb, Cu, Se and V. In a compromised environmental scenario, concomitant presence of metals and anthropogenic compounds (Hydrocarbons, Halogenated Solvents and Nitrates), the conduction of the ERA reveals instead potential adverse effects not only for the aquatic communities, but also for small birds and fish. The data, acquired through the various survey steps, lay the foundations for an environmental characterization of the study area, to define both the operational priority criteria aimed at environmental rehabilitation, and the precautionary limit values for sensitive environmental targets, this last defined at a site-specific scale.