Applicazione di metodi geochimici in aree a intensa pressione antropica. Il caso di studio delle discariche RSU

In order to identify new survey methods for environmental characterization of areas affected by anthropogenic pressure, several geochemical investigations were conducted in two municipal solid waste landfills of Central Italy: Cerratina landfill and Cerreto landfill. Cerratina landfill is located in an alluvial plain of the lower Sangro river. The area is characterized by a substrate of marine origin formed by clay and sand at the base and coarse sands upwards to sands and conglomerates at the top of the formation. In this area were conducted geochemical investigations on groundwater beneath the landfill. The results of chemical analyses indicate that the samples collected from boreholes located downgradient from the landfill are contaminated. The principal contaminants are Cl-, NH4+, Fe, As, Cr, B, Hg and Zn, which exceed the limit provided by Dlgs 152/2006 during different monitoring campaigns. The boron, tritium and strontium isotopic composition of the collected water samples was analysed to evaluate the principal water-rock interaction processes and source of contamination. The results indicate that contaminated groundwater show highest tritium data and lower δ11B and 87Sr/86Sr ratio. Boron isotopes show that there are two boron sources in the study area, which are geogenic and anthropogenic sources. Sr isotope results show that sample located upgradient from the site presents lower Sr concentration and highest Sr isotopic values, which reflects weathered bedrock, while boreholes located downgradient from the site show lowest Sr values and 87Sr/86Sr ratio, probably due to pollution by landfill leachate. Another important result was obtained by rare earths elements analyses. A positive Gadolinium anomaly was reported for one sample of studied area which reflects the anthropogenic input of the REEs in groundwater. Cerreto landfill is located in an alluvial plain of Lazio, central Italy. The area is characterized by a substrate of continental deposits formed by clay and sand, and alluvial deposits associated with different depositional events of the main rivers presents in the area. Were conducted geochemical investigation on groundwater and soils located in the landfill site. The results show that major and trace elements for soil are below the limit provided by Italian law. Rare earths elements pattern of soils were used to evaluate possible anomalies presence and to investigate soil parent material for identifying background values of study area. The geochemical investigations show that some elements, in topsoil, present higher concentration respect to background values. Geoaccumulation index and enrichment factor show possible contamination phenomena of Ni, Cu, Cd e Pb. The results obtained for groundwater show that Fe, Mn and As exceed the limit provided by Dlgs 152/2006, but according to results obtained for soil, these elements naturally occur in the area so their principal source is geological substrate.