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In the last decades, many efforts have been made to predict and monitor the effects of natural and anthropogenic phenomena that can affect the quality of life of the human beings. Among these potentially dangerous phenomena, the geochemical contamination of the water, soils and sediments requires an accurate knowledge of the distribution and origin of the potential harmful elements in the environment for the assessment and management of the consequent risks. The wide availability of new and advanced tools, like Geographic Information Systems (GISs), sophisticated analytical techniques (ICP-MS and Pb isotopic ratios) and geostatistics (multivariate statistics), provides a efficient methodology for geochemical mapping and environmental analysis, depicting the distribution and interactions among hazardous phenomena, geogenic and anthropogenic sources and objects exposed to the risk. This thesis investigates advanced techniques to develop geochemical exploration studies for the environmental quality assessment in the Huelva Province (Spain) and Zambales Province (the Philippines), which has been analyzed through the calculation of accurate geochemical maps and the analysis of the relationships between geochemical anomalies and contamination sources. One of these techniques is the use of Pb isotopic ratios, measured in soil and human hair, as signature to identify the anthropogenic and geogenic sources of harmful elements in the environment. The Huelva Province, where three sub-areas have been selected, is located in Andalusia, in the southwest of the Iberian Peninsula. Soil and human hair samples were collected prepared and analyzed using ICP-MS. These analytical results have been used in a GIS to obtain accurate geochemical maps and an environmental hazard assessment based on the calculation of contamination factors and pollution index. To individuate the source of contamination, lead isotopic analysis where performed for selected soil and human hair samples. The spatial analysis of the geochemical concentrations and isotopic signatures allowed to recognize the main relationships among geology, land use and the occurrence of harmful elements in the environment and human beings. The environmental assessment shows sectors in the three study areas where multi-element concentration of metals may represent a risk for the human health. Lead isotopic analysis for soil and human hair evidenced two signatures of the contamination sources, one related to the mineralization and the other to pesticides and gasoline. The Zambales Province is located in the western part of the Luzon Island in the Philippines. Stream sediment samples have been collected, prepared and analyzed with ICP-MS. Geochemical elements have been grouped in three associations by means of a factor analysis. Finally, the spatial distribution of the element concentrations in the environment has been identified with a new GIS algorithm developed to produce geochemical maps at the watershed level. The calculation of background values for harmful elements has been accomplished for the first time in the area. Anomalous sectors with concentration of geochemical elements well above the background values were identified, representing a potential environmental risk. The study also identified the occurrence of metals and other elements of economic interest. Additional researches, not strictly related to the main topic of the thesis, have been carried out during the PhD. In these studies, GIS tools have been used to analyze different factors having an influence on the environment, like marine and coastal pollution, and hydrogeological, seismic and volcanic events, to provide a comprehensive view of a territory and its relationships with the human activities. These studies have been focused on: 1) marine and coastal pollution in the area of the decommissioned industrial site of Bagnoli, in the city of Naples (Italy). Sediment samples have been analyzed for inorganic elements, Polychlorobiphenyls (PCB) and Polycyclic Aromatic Hydrocarbons (PAHs). Geochemical maps and identification of areas under geochemical risk in the marine area have then been produced by means of a GIS; 2) hydrogeological events, with the definition of a new GIS algorithm for semi-automated and accurate alluvial fans mapping over wide regions; 3) volcano-basement interplay, with the analysis and GIS modeling of the relationships between the evolution of the Colima Volcanic Complex (Mexico) and the occurrence of active volcano-tectonic and regional faults; 4) seismic risk, with the GIS analysis of the spatial relationships among geological, geotechnical and geophysical data, for the seismic characterization of the sector of the Lombardia Region (Italy) affected by the May-June 2012 seismic crisis. The different studies that have been carried out during the PhD program represent a contribution toward the definition of efficient tools and technical procedures, useful for accurate natural and anthropogenic hazards assessment, risks mitigation and better land use plans. |
