A structural and geophysical approach to the study of fractured aquifers in the Scansano-Magliano in Toscana Ridge, southern Tuscany, Italy   总被引：1，自引：0，他引：1  

Roberto Francese  Francesco Mazzarini  Andrea Bistacchi  Gianfranco Morelli  Giorgio Pasquarè  Nicola Praticelli  Henry Robain  Nigel Wardell  Annalisa Zaja 《Hydrogeology Journal》2009,17(5):1233-1246

Fresh water availability has recently become a serious concern in the Italian Apennines, as various activities rely on a predictable supply. Along the ridge between Scansano and Magliano in Toscana, in southern Tuscany, the situation is further complicated by contamination of the nearby alluvial aquifers. Aquifers locally consist of thin fractured reservoirs, generally within low-permeability formations, and it can be difficult to plan the exploitation of resources based on conventional techniques. An integrated study based on geological data investigated the link between tectonics and groundwater circulation, to better define the hydrological model. After the regional identification of fault and fracture patterns, a major structure was investigated in detail to accurately map its spatial position and to understand the geometry and properties of the associated aquifer and assess its exploitation potential. The subsurface around the fault zone was clearly imaged using ground probing radar, two-dimensional and three-dimensional resistivity tomography, and three-dimensional shallow seismic surveys. The vertical and horizontal contacts between the different geological units of the Ligurian and Tuscan series were resolved with a high degree of spatial accuracy. Three-dimensional high-resolution geophysical imaging proved to be a very effective means of characterising small-scale fractured reservoirs.  相似文献   

Impacts of maintenance channel dredging in a northern Adriatic coastal lagoon. I: Effects on sediment properties,contamination and toxicity     

Roberta Guerra  Andrea PasterisMassimo Ponti 《Estuarine, Coastal and Shelf Science》2009

Conservation and management of coastal lagoons envisage direct human intervention. To prevent siltation and to preserve the hydrodynamics features of the lagoon system, the inner channels undergo regular maintenance dredging.  相似文献   

Impacts of maintenance channel dredging in a northern Adriatic coastal lagoon. II: Effects on macrobenthic assemblages in channels and ponds     

Massimo Ponti  Andrea PasterisRoberta Guerra  Marco Abbiati 《Estuarine, Coastal and Shelf Science》2009

Coastal lagoons are ephemeral habitats whose conservation requires human intervention, such as maintenance dredging of inner channels. Dredging can reduce the abundance of benthic species due to the removal of individuals with the sediment, modify sediment properties, and resuspend fine sediment, nutrients and pollutants, which can lead to eutrophication, hypoxic events and increasing toxicity. Both direct effects in the dredged channel and possible indirect effects in surrounding shallow areas could be expected. This study assesses the effects of the channel maintenance dredging, performed between October 2004 and August 2005, on the invertebrate assemblages both in channels and adjacent ponds in the northern Adriatic coastal lagoon of Pialassa Baiona. The lagoon is affected by eutrophication, chemical and thermal pollution from wastewater treatment and power plants. Three impacted sites were located in the dredged channel and three in the adjacent interconnected shallow water ponds, while three non-impacted sites were located in a channel and in a pond far from the dredged area. Replicate samples were collected from each site one time before and one time after the dredging operations. Despite the extent of the intervention, effects of the dredging on macrobenthic assemblages were detected only within the dredged channel, while in the surrounding ponds no clear and unequivocal effects were found. In particular the dredging could have promoted the increase of the abundance of the polychaete Streblospio shrubsolii in the southern and central parts of the dredged channel and the increase in abundance of the amphipod Corophium insidiosum in the northern side, compared to the controls. Instead, species diversity was reduced in the central and northern parts of the dredged channel. These effects on the macrobenthic invertebrate assemblages could be related to the observed changes of sediment characteristics, contamination and toxicity. Overall, direct effects on benthic assemblages in the dredged channels were more detectable than the possible secondary effects in the surrounding shallow ponds, where the higher spatial heterogeneity can mask any relevant effects.  相似文献   

Development and validation of a finite element morphological model for shallow water basins     

Christian Ferrarin  Georg Umgiesser  Andrea Cucco  Tai-Wen Hsu  Aron Roland  Carl L. Amos 《Coastal Engineering》2008

Recognising the importance of understanding sediment dynamics to evaluate the status of a coastal lagoon environment, this work has been focused on the investigation of the hydrodynamic and sediment transport processes occurring in such basins. In order to describe the lagoon system, a modelling approach combining hydrodynamics, waves and sediment dynamics has been developed. The framework of the numerical model consists of a finite element hydrodynamic model, a third generation finite element spectral wave model and a sediment transport and morphodynamic model for both cohesive and non-cohesive sediments. The model adopts the finite element technique for spatial integration, which has the advantage to describe more accurately complicated bathymetry and irregular boundaries for shallow water areas. The developed model has been applied to test cases and to a very shallow tidal lagoon, the Venice Lagoon, Italy. Numerical results show good agreement with water level, waves and turbidity measurements collected in several monitoring stations inside the Lagoon of Venice. Such a model represents an indispensable tool in analysing coastal problems and assessing morphological impacts of human interference.  相似文献   

Comparison of spectral characteristics of precipitation from radar estimates and COSMO-model predicted fields     

Matteo Willeit  Roberta Amorati  Andrea Montani  Valentina Pavan  Maria Stefania Tesini 《Meteorology and Atmospheric Physics》2015,127(2):191-203

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Atmospheric Circulation Changes in Response to an Observed Stratospheric Zonal Ozone Anomaly     

Dieter H. W. Peters  Andrea Schneidereit  Marianne Bügelmayer  Christoph Zülicke  Ingo Kirchner 《大气与海洋》2015,53(1):74-88

Abstract

In a sensitivity study, the influence of an observed stratospheric zonal ozone anomaly on the atmospheric circulation was investigated using the Fifth Generation European Centre Hamburg Model (ECHAM5) which is a general circulation model. The model was run from 1960 to 1999 (40 years) with a mean seasonal cycle of zonally symmetric ozone. In order to isolate the induced dynamical influence of the observed zonally asymmetric part of the three-dimensional stratospheric ozone, a second run was performed for the boreal extratropics using prescribed monthly means from the 40-year reanalysis dataset from the European Centre for Medium-range Weather Forecasts (ERA-40). The main findings are the interdecadal westward shift of the polar vortex at about 65°N and a significant increase in the number of stratospheric sudden warmings during the 1980–99 period. Under the action of zonally asymmetric ozone a decrease in the Arctic Oscillation was identified between the mid-1980s and the mid-1990s. The lag correlation between the mean Arctic Oscillation at the surface and the daily stratospheric northern annular mode increased in mid-winter. Furthermore, we examined the influence of the stratospheric zonal ozone anomaly on Rossby wave breaking in the upper troposphere and found a significant westward shift of poleward Rossby wave breaking events over western Europe in the winter. By this we show that the stratospheric zonal ozone anomaly has a strong influence on the tropospheric circulation as a result of enhanced dynamical coupling processes.  相似文献   

POLARIX: a pathfinder mission of X-ray polarimetry     

Enrico Costa  Ronaldo Bellazzini  Gianpiero Tagliaferri  Giorgio Matt  Andrea Argan  Primo Attinà  Luca Baldini  Stefano Basso  Alessandro Brez  Oberto Citterio  Sergio Di Cosimo  Vincenzo Cotroneo  Sergio Fabiani  Marco Feroci  Antonella Ferri  Luca Latronico  Francesco Lazzarotto  Massimo Minuti  Ennio Morelli  Fabio Muleri  Lucio Nicolini  Giovanni Pareschi  Giuseppe Di Persio  Michele Pinchera  Massimiliano Razzano  Luigia Reboa  Alda Rubini  Antonio Maria Salonico  Carmelo Sgro’  Paolo Soffitta  Gloria Spandre  Daniele Spiga  Alessio Trois 《Experimental Astronomy》2010,28(2-3):137-183

Since the birth of X-ray astronomy, spectral, spatial and timing observation improved dramatically, procuring a wealth of information on the majority of the classes of the celestial sources. Polarimetry, instead, remained basically unprobed. X-ray polarimetry promises to provide additional information procuring two new observable quantities, the degree and the angle of polarization. Polarization from celestial X-ray sources may derive from emission mechanisms themselves such as cyclotron, synchrotron and non-thermal bremsstrahlung, from scattering in aspheric accreting plasmas, such as disks, blobs and columns and from the presence of extreme magnetic field by means of vacuum polarization and birefringence. Matter in strong gravity fields and Quantum Gravity effects can be studied by X-ray polarimetry, too. POLARIX is a mission dedicated to X-ray polarimetry. It exploits the polarimetric response of a Gas Pixel Detector, combined with position sensitivity, that, at the focus of a telescope, results in a huge increase of sensitivity. The heart of the detector is an Application-Specific Integrated Circuit (ASIC) chip with 105,600 pixels each one containing a full complete electronic chain to image the track produced by the photoelectron. Three Gas Pixel Detectors are coupled with three X-ray optics which are the heritage of JET-X mission. A filter wheel hosting calibration sources unpolarized and polarized is dedicated to each detector for periodic on-ground and in-flight calibration. POLARIX will measure time resolved X-ray polarization with an angular resolution of about 20 arcsec in a field of view of 15 × 15 arcmin and with an energy resolution of 20% at 6 keV. The Minimum Detectable Polarization is 12% for a source having a flux of 1 mCrab and 10⁵ s of observing time. The satellite will be placed in an equatorial orbit of 505 km of altitude by a Vega launcher. The telemetry down-link station will be Malindi. The pointing of POLARIX satellite will be gyroless and it will perform a double pointing during the earth occultation of one source, so maximizing the scientific return. POLARIX data are for 75% open to the community while 25% + SVP (Science Verification Phase, 1 month of operation) is dedicated to a core program activity open to the contribution of associated scientists. The planned duration of the mission is one year plus three months of commissioning and SVP, suitable to perform most of the basic science within the reach of this instrument. A nice to have idea is to use the same existing mandrels to build two additional telescopes of iridium with carbon coating plus two more detectors. The effective area in this case would be almost doubled.  相似文献   

A visual basic spreadsheet macro for geochemical background analysis   总被引：3，自引：0，他引：3  

Nakić Z  Posavec K  Bacani A 《Ground water》2007,45(5):642-647

A Visual Basic macro entitled BACKGROUND calculates geochemical background values of chemical parameters and estimates threshold values separating background data from anomalies. The macro uses two statistical methods, the iterative 2-sigma technique and the calculated distribution function, and integrates these model-based objective methods into a widely accessible platform (i.e., MS Excel). The macro offers the possibility for automated processing of geochemical data and enables an automated generation of background range and threshold values for chemical parameters.  相似文献   

Bromine cycle in subduction zones through in situ Br monitoring in diamond anvil cells     

Hélène Bureau  Eddy Foy  Andrea Somogyi  Guilhem Simon 《Geochimica et cosmochimica acta》2010,74(13):3839-155

The geochemical partitioning of bromine between hydrous haplogranitic melts, initially enriched with respect to Br and aqueous fluids, has been continuously monitored in situ during decompression. Experiments were carried out in diamond anvil cells from 890 °C to room temperature and from 1.7 GPa to room pressure, typically from high P, T conditions corresponding to total miscibility (presence of a supercritical fluid). Br contents were measured in aqueous fluids, hydrous melts and supercritical fluids. Partition coefficients of bromine were characterized at pressure and temperature between fluids, hydrous melts and/or glasses, as appropriate: D^Br_fluid/melt = (Br)_fluid/(Br)_melt, ranges from 2.18 to 9.2 ± 0.5 for conditions within the ranges 0.66-1.7 GPa, 590-890 °C; and D^Br_fluid/glass = (Br)_fluid/(Br)_glass ranges from 60 to 375 at room conditions. The results suggest that because high pressure melts and fluids are capable of accepting high concentrations of bromine, this element may be efficiently removed from the slab to the mantle source of arc magmas. We show that Br may be highly concentrated in subduction zone magmas and strongly enriched in subduction-related volcanic gases, because its mobility is strongly correlated with that of water during magma degassing. Furthermore, our experimental results suggest that a non negligible part of Br present in the subducted slab may remain in the down-going slab, being transported toward the transition zone. This indicates that the Br cycle in subduction zones is in fact divided in two related but independent parts: (1) a shallower one where recycled Br may leave the slab with a water and silica-bearing “fluid” leading to enriched arc magmas that return Br to the atmosphere. (2) A deeper cycle where Br may be recycled back to the mantle maybe to the transition zone, where it may be present in high pressure water-rich metasomatic fluids.  相似文献   

Spectroscopic analysis (FTIR, Raman) of water in mafic and intermediate glasses and glass inclusions   总被引：1，自引：0，他引：1  

Maxime Mercier  Andrea Di Muro  Nicole Métrich  Olfa Belhadj 《Geochimica et cosmochimica acta》2010,74(19):5641-5656

Micro-Raman spectroscopy, even though a very promising technique, is not still routinely applied to analyse H₂O in silicate glasses. The accuracy of Raman water determinations critically depends on the capability to predict and take into account both the matrix effects (bulk glass composition) and the analytical conditions on band intensities. On the other hand, micro-Fourier transform infrared spectroscopy is commonly used to measure the hydrous absorbing species (e.g., hydroxyl OH⁻ and molecular H₂O) in natural glasses, but requires critical assumptions for the study of crystal-hosted glasses. Here, we quantify for the first time the matrix effect of Raman external calibration procedures for the quantification of the total H₂O content (H₂O_T = OH⁻ + H₂O_m) in natural silicate glasses. The procedures are based on the calibration of either the absolute (external calibration) or scaled (parameterisation) intensity of the 3550 cm⁻¹ band. A total of 67 mafic (basanite, basalt) and intermediate (andesite) glasses hosted in olivines, having between 0.2 and 4.8 wt% of H₂O, was analysed. Our new dataset demonstrates, for given water content, the height (intensity) of Raman H₂O_T band depends on glass density, reflectance and water environment. Hence this matrix effect must be considered in the quantification of H₂O by Raman spectroscopy irrespective of the procedure, whereas the parameterisation mainly helps to predict and verify the self-consistency of the Raman results. In addition, to validate the capability of the micro-Raman to accurately determine the H₂O content of multicomponent aluminosilicate glasses, a subset of 23 glasses was analysed by both micro-Raman and micro-FTIR spectroscopy using the band at 3550 cm⁻¹. We provide new FTIR absorptivity coefficients (ε₃₅₅₀) for basalt (62.80 ± 0.8 L mol⁻¹ cm⁻¹) and basanite (43.96 ± 0.6 L mol⁻¹ cm⁻¹). These values, together with an exhaustive review of literature data, confirm the non-linear decline of the FTIR absorptivity coefficient (ε₃₅₅₀) as the glass depolymerisation increases. We demonstrate the good agreement between micro-FTIR and micro-Raman determination of H₂O in silicate glasses when the matrix effects are properly considered.  相似文献