Hydrogeochemistry and strontium isotopes in the Arno River Basin (Tuscany, Italy): Constraints on natural controls by statistical modeling

In this paper the chemistry of major and trace elements and, for the first time, strontium isotopic ratios measured in running waters from the Arno River Basin (Tuscany, central-northern Italy) and thermal springs discharging in the same hydrographic system are presented and discussed. Classical graphical methods (e.g. mixing diagrams) have here been improved to identify, in a correct statistical sample space, extreme chemical compositions attributable to the action of geochemical processes and/or inherited from specific lithologies (namely contributions or components 1, 2 and 3) to be used in inverse modeling procedures, due to the absence of clear end-members. A linear least squares problem, with non-negativity constraints and distances, as required for compositional data (convex linear mixing) was solved by considering the contribution of the most discriminant variables given by the ⁸⁷Sr/⁸⁶Sr isotopic ratios and the concentration of Ca²⁺, Mg²⁺, Sr and Rb. Following such approach, it can be assumed (p < 0.05) that component 1, characterized by a Ca²⁺(Mg²⁺)– radiogenic-rich (⁸⁷Sr/⁸⁶Sr = 0.71274; Rb/Sr = 0.039), represents a dominant feature at basin scale, with a weight ranging from 69% to 100%. Much lower percentages are related to component 2, represented by a Ca²⁺(Mg²⁺)– facies with intermediate ⁸⁷Sr/⁸⁶Sr (0.70874) and low Rb/Sr (2.8 × 10⁻⁴) ratios and component 3, identified by Ca²⁺– facies with less radiogenic ⁸⁷Sr/⁸⁶Sr (0.70827) and low Mg²⁺/Ca²⁺ (0.011) ratios. These components are mainly dominated by the dissolution of evaporitic rocks and/or mixing with thermal waters in the southern part of the Arno River Basin and by dissolution of the carbonatic fraction, kinetically favored with respect to that of the silicatic minerals, in the upper reaches of the main course and its tributaries, respectively.     

Material screening and selection for XENON100

Results of the extensive radioactivity screening campaign to identify materials for the construction of XENON100 are reported. This dark matter search experiment is operated underground at Laboratori Nazionali del Gran Sasso (LNGS), Italy. Several ultra sensitive High Purity Germanium detectors (HPGe) have been used for gamma ray spectrometry. Mass spectrometry has been applied for a few low mass plastic samples. Detailed tables with the radioactive contaminations of all screened samples are presented, together with the implications for XENON100.     

Coastal deformation between the Versilia and the Garigliano plains (Italy) since the last interglacial stage

The opening of the north‐central Tyrrhenian Sea is the result of the Cretaceous–Paleogene alpine collision, which triggered a series of regional uplift, subsidence and transcurrent tectonic mechanisms along the coastal Tyrrhenian sectors of peninsular Italy. These tectonic processes, in conjunction with the effects of glacio‐ and hydro‐isostasy during the Quaternary, produced substantial crustal responses that, in some cases, reached metres in extent. In the study of coastal neotectonics, geomorphological markers of the last interglacial maximum, corresponding to marine isotope stage 5.5, are generally used to quantify the magnitude of the vertical crustal displacements that have occurred since 125 kyr. Through altimetrical, palaeoenvironmental and chronological reinterpretation of the most significant works published since 1913, combined with an additional set of data reported here, a detailed reconstruction of the shoreline displacements evident along 500 km of coast between northern Tuscany and southern Latium is presented. The reconstruction was carried out by quantifying the vertical movement since the last interglacial period and by identifying the tectonic behaviour of different coastal sectors. This has been done by carefully choosing the eustatic marker, among those available at each study site, in order to minimize the margin of error associated with the measurements. Copyright © 2003 John Wiley & Sons, Ltd.     

Assessment of nitrate contamination risk: The Italian experience

The purpose of this study is to show the results of the Italian research project of national interest (PRIN) launched in 2006 and finished in 2008, concerning the “assessment of groundwater contamination risk by nitrates assessment”. The project verified the IPNOA method for nitrate groundwater contamination risk assessment in four test-sites of Italy. The IPNOA is a parametric index which assesses the potential hazard of nitrate contamination originating from agriculture on a regional scale. The method integrates two categories of parameters: the hazard factors (HF), which represent all farming activities that cause, or might cause, an impact on soil quality in terms of nitrate (use of fertilisers, application of livestock and poultry manure, food industry wastewater and urban sludge), and the control factors (CF) which adapt the hazard factors to the characteristics of the site (geographical location, climatic conditions and agronomic practices). Finally, the Potential Risk Map is obtained by coupling the potential hazard of nitrate pollution (IPNOA) and the aquifer Contamination Vulnerability Map. The project was carried out by five Research Units (RU) from the Politecnico di Torino, Universities of Piacenza, Florence, Naples and Palermo. The geochemistry of groundwaters from the four test-sites was studied to determine the distribution of nitrate, and to evaluate groundwater chemical facies. All the study areas are affected by groundwater nitrate contamination and often by hydrogeochemical peculiarities. In some cases isotopic study, δ¹⁸O–NO₃δ¹⁵N–NO₃, allowed to differentiate nitrates of chemical fertilisers from those of biological origin, as well as denitrification processes.