705 research outputs found

    Hydrogeochemistry and Groundwater Quality Assessment in the High Agri Valley (Southern Italy)

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    The High Agri Valley (southern Italy) is one of the largest intermontane basin of the southern Apennines affected by intensive agricultural and industrial activities. The study of groundwater chemical features provides much important information useful in water resource management. In this study, hydrogeochemical investigations coupled with multivariate statistics, saturation indices, and stable isotope composition (δD and δ18O) were conducted in the High Agri Valley to determine the chemical composition of groundwater and to define the geogenic and anthropogenic influences on groundwater quality. Twenty-four sampling point ( including well and spring waters) have been examined. The isotopic data revealed that groundwater has a meteoric origin. Well waters, located on recent alluvial-lacustrine deposits in shallow porous aquifers at the valley floor, are influenced by seasonal rainfall events and show shallow circuits; conversely, spring waters from fissured and/or karstified aquifers are probably associated to deeper and longer hydrogeological circuits. The R -mode factor analysis shows that three factors explain 94% of the total variance, and F1 represents the combined effect of dolomite and silicate dissolution to explain most water chemistry. In addition, very low contents of trace elements were detected, and their distribution was principally related to natural input. Only two well waters, used for irrigation use, show critical issue for NO3- concentrations, whose values are linked to agricultural activities. Groundwater quality strongly affects the management of water resources, as well as their suitability for domestic, agricultural, and industrial uses. Overall, our results were considered fulfilling the requirements for the inorganic component of the Water Framework Directive and Italian legislation for drinking purposes. The water quality for irrigation is from "good to permissible" to "excellent to good" although salinity and relatively high content of Mg2+ can occasionally be critical

    Privileged burial in the Pava Pieve (Siena, 8th century AD)

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    During the 6th archaeological excavation campaign performed at the «Pieve di Pava» (San Giovanni d’Asso, Siena, Italy) in the summer of 2009, a stone-lined burial of a high-status single individual (US 2378) was discovered, covered by a monolithic slab and placed in front of the altar. The tomb is about 160 cm long, 40 cm wide and over 70 cm deep. The skeletal remains of a young male (18-20 years), not in anatomical connection, were found on the floor of the tomb. 14C dating revealed a period between 650 and 688 AD. Stable isotope analysis (18O, 13C, 15N) attested that he was a member of the local community, with a diet quite rich in animal proteins. We are in presence of the secondary burial of an eminent personage, perhaps a saint, likely to have been transported to the church in a sack of perishable material, possibly textile, which caused their alignment along a curved line, as clearly demonstrated by the circular delimitation of the bones. The body was probably used for the re-consecration of the church, following the restoration works of the 8th century. The paleopathological study diagnosed a case of acromesomelic dysplasia, a congenital anomaly with disproportionate limbs: short, enlarged distal segments (radius-ulna and tibia), almost normal proximal segments (humerus and femur), short stature of about 150 cm, and bilateral fibular agenesis. Tibiae malformation and fibulae agenesis led to bilateral talipes valgus, with major walking problems. Extensive enthesopathies in the upper limbs indicate the use of crutches

    Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in Na-Cl brackish waters of north-western Sardinia, Italy

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    Abstract. Throughout the Mediterranean, salinization threatens water quality, especially in coastal areas. This salinization is the result of concomitant processes related to both seawater intrusion and water–rock interaction, which in some cases are virtually indistinguishable. In the Nurra region of northwestern Sardinia, recent salinization related to marine water intrusion has been caused by aquifer exploitation. However, the geology of this region records a long history from the Palaeozoic to the Quaternary, and is structurally complex and comprises a wide variety of lithologies, including Triassic evaporites. Determining the origin of the saline component of the Jurassic and Triassic aquifers in the Nurra region may provide a useful and more general model for salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activity and recent climatic change, the Nurra has become vulnerable to desertification and, in common with other Mediterranean islands, surface water resources periodically suffer from severe shortages. With this in mind, we report new data regarding brackish and surface waters (outcrop and lake samples) of the Na-Cl type from the Nurra region, including major ions and selected trace elements (B, Br, I, and Sr), in addition to isotopic data including δ18O, δD in water, and δ34S and δ18O in dissolved SO4. To identify the origin of the salinity more precisely, we also analysed the mineralogical and isotopic composition of Triassic evaporites. The brackish waters have Cl contents of up to 2025 mg L−1 , and the ratios between dissolved ions and Cl, with the exception of the Br / Cl ratio, are not those expected on the basis of simple mixing between rainwater and seawater. The δ18O and δD data indicate that most of the waters fall between the regional meteoric water line and the global meteoric water line, supporting the conclusion that they are meteoric in origin. A significant consequence of the meteoric origin of the Na-Cl-type water studied here is that the Br / Cl ratio, extensively used to assess the origin of salinity in fresh water, should be used with care in carbonate aquifers that are near the coast. Overall, δ34S and δ18O levels in dissolved SO4 suggest that water–rock interaction is responsible for the Na-Cl brackish composition of the water hosted by the Jurassic and Triassic aquifers of the Nurra, and this is consistent with the geology and lithological features of the study area. Evaporite dissolution may also explain the high Cl content, as halite was detected within the gypsum deposits. Finally, these Na-Cl brackish waters are undersaturated with respect to the more soluble salts, implying that in a climate evolving toward semi-arid conditions, the salinization process could intensify dramatically in the near future

    Dosimetric characterization of CVD diamonds irradiated with 62 MeV proton beams

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    Diamond is potentially a very suitable material for use as on-line radiation dosimeter. Recent advances in the synthesis of polycrystalline diamond by chemical vapor deposition (CVD) techniques have produced material with electronic properties suitable for dosimetry applications. In this work the possibility to use a segmented commercial CVD detector in the dosimetry of proton beams has been investigated. The response as function of dose, dose rate, the priming and the rise time have been investigated thoroughly. This study shows the suitability of CVD diamond for dosimetry of clinical 62 MeV proton beams. r 2005 Elsevier B.V. All rights reserved

    Dosimetric characterization of CVD diamonds in photon, electron and proton beams

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    The purpose of this work is the characterization, in an on line configuration, of the dosimetric response of a commercial CVD diamond. The study shows the possibility of using CVD diamond for dosimetric purposes with clinical, high-energy electron (4-15 MeV), photon (6-15 MV) and proton (62 MeV) beams

    Status of the Cylindical-GEM project for the KLOE-2 Inner Tracker

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    The status of the R&D on the Cylindrical-GEM (CGEM) detector foreseen as Inner Tracker for KLOE-2, the upgrade of the KLOE experiment at the DAFNE phi-factory, will be presented. The R&D includes several activities: i) the construction and complete characterization of the full-size CGEM prototype, equipped with 650 microns pitch 1-D longitudinal strips; ii) the study of the 2-D readout with XV patterned strips and operation in magnetic field (up to 1.5T), performed with small planar prototypes in a dedicated test at the H4-SPS beam facility; iii) the characterization of the single-mask GEM technology for the realization of large-area GEM foils.Comment: 4 pages, 10 figures, Presented at Vienna Conference on Instrumentation (Feb 15-20, 2010, Vienna, Austria). Submitted to the Proceeding

    Composition and structural modifications to the AI/AISI 316L sintered steel interface induced by heat treatments

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    After heat treatment, the aluminium coating, deposited on sintered AISI 316L austenitic stainless steel forms an interdiffusion layer. Aluminium diffuses beyond the layer/steel interface, mostly along the interconnected porosities, penetrating into the sintered steel for about 80 gm, and causing a nitrogen exchange reaction with the Cr2N phase. This leads to the formation of AlN particles. At the beginning these are tiny, then they subsequently coalesce and migrate outwards through the interdiffusion layer. The vapour phase aluminium diffusion is in accordance with thermodynamical data.At the layer/coated sintered steel interface, on the steel side, the cavity surfaces are covered by aluminium and chromium mixed films. In uncoated heat treated sintered steels, the chromium oxide films are present in all the volume. The anodic behaviour of aluminium coated and heat treated (700 -900°C) sintered steels is much better than that of the uncoated steels heat treated at the same temperatures.The improvement can be attributed to the Cr2N and Al reaction which makes passivation easier. With 1000°C heat treatment, a worsening is observed compared to the lower temperatures
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