A research agreement was approved in 2009 among the Tuscany Region, the Institute of Geosciences and Earth Resources of CNR based in Pisa and the Tuscan Universities of Florence, Pisa, and Siena, for the implementation of a research and innovation project in the field of environmental geochemistry, named “Geobasi Toscana”. The aims of this two-year project are the determination of the natural geochemical baselines for several substances, some of which are potentially harmful, as well as the reorganization and elaboration of all available geochemical data for natural waters (including surface-, ground-, and transition-waters) and active stream sediments. The “Geobasi Toscana” project continues along the path opened in 2004-2006 by the “Geobasi” project, which was funded by the ministry of the University and Scientific Research of Italy and involved several Italian universities to tackle the complex meaning of elemental compositions in different geo-environmental matrices by means of an integrated multidisciplinary approach. In turn, the roots of the “Geobasi” project are found in the guidelines outlined through a previous APAT-CNR research agreement, whose main outcome is the National Geochemical Archive of Italy (Ottonello, 2008). In this reference framework, it was possible to test innovative approaches in geochemical mapping during the development of the “Geobasi Toscana” project. These methods were then applied to study the behavior of Cd, Hg, Ni, Pb, As, and Cr in the active stream sediments of the Siena area as well as the distribution of other parameters, including U, Cl, SO4, and Hardness in the fluvial waters of the whole region. Analytical data used to study stream sediments refer to 417 samples collected in the Siena province over a total surface area of 2000 km2 approximately, with a density of 1 sample each 5 km2. Analytical data of 949 fluvial water samples come from CNEN geochemical surveys carried out in the sixties. They were processed using both deterministic and geo-statistical approaches. In particular, methods of spatial analysis developed for studying compositional data were applied. In this type of data (percentages, parts per million, molar fractions, etc.), each variable represents a given proportion of a total, which is fixed a priori. From the geometric point of view, compositional data does not occupy the real space, whose dimensions are equal to the number of variables, but are situated in a restricted space, known as simplex (Aitchison, 1986), which is part of the real space. This constrained, non-Euclidean geometry causes several problems if data analysis is approached using the methods of classic statistics. In this research works, new graphical and numerical methods were therefore proposed, respecting the geometric peculiarities of the sample space. Results were discussed in the light of the geochemical behavior of the considered elements and taking into account the geo-lithological characteristics of the investigated areas.

Testing of innovative approaches in geochemical mapping: the experience of the “Geobasi Toscana” project

MACERA, PATRIZIA;
2011

Abstract

A research agreement was approved in 2009 among the Tuscany Region, the Institute of Geosciences and Earth Resources of CNR based in Pisa and the Tuscan Universities of Florence, Pisa, and Siena, for the implementation of a research and innovation project in the field of environmental geochemistry, named “Geobasi Toscana”. The aims of this two-year project are the determination of the natural geochemical baselines for several substances, some of which are potentially harmful, as well as the reorganization and elaboration of all available geochemical data for natural waters (including surface-, ground-, and transition-waters) and active stream sediments. The “Geobasi Toscana” project continues along the path opened in 2004-2006 by the “Geobasi” project, which was funded by the ministry of the University and Scientific Research of Italy and involved several Italian universities to tackle the complex meaning of elemental compositions in different geo-environmental matrices by means of an integrated multidisciplinary approach. In turn, the roots of the “Geobasi” project are found in the guidelines outlined through a previous APAT-CNR research agreement, whose main outcome is the National Geochemical Archive of Italy (Ottonello, 2008). In this reference framework, it was possible to test innovative approaches in geochemical mapping during the development of the “Geobasi Toscana” project. These methods were then applied to study the behavior of Cd, Hg, Ni, Pb, As, and Cr in the active stream sediments of the Siena area as well as the distribution of other parameters, including U, Cl, SO4, and Hardness in the fluvial waters of the whole region. Analytical data used to study stream sediments refer to 417 samples collected in the Siena province over a total surface area of 2000 km2 approximately, with a density of 1 sample each 5 km2. Analytical data of 949 fluvial water samples come from CNEN geochemical surveys carried out in the sixties. They were processed using both deterministic and geo-statistical approaches. In particular, methods of spatial analysis developed for studying compositional data were applied. In this type of data (percentages, parts per million, molar fractions, etc.), each variable represents a given proportion of a total, which is fixed a priori. From the geometric point of view, compositional data does not occupy the real space, whose dimensions are equal to the number of variables, but are situated in a restricted space, known as simplex (Aitchison, 1986), which is part of the real space. This constrained, non-Euclidean geometry causes several problems if data analysis is approached using the methods of classic statistics. In this research works, new graphical and numerical methods were therefore proposed, respecting the geometric peculiarities of the sample space. Results were discussed in the light of the geochemical behavior of the considered elements and taking into account the geo-lithological characteristics of the investigated areas.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/151635
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