Contribution of Sponge Spicules to the Composition of Biogenic Silica in the Ligurian Sea     

Giorgio  Bavestrello  Riccardo  Cattaneo-Vietti  Carlo  Cerrano  Stefania  Cerutti Michele  Sará 《Marine Ecology》1996,17(1-3):41-50

Abstract. The importance of sponge spicules in the turnover of biogenic silica (BSi) in the detritic bottoms of the Eastern Ligurian Riviera was evaluated by studying sediment cores and the detrital matter collected by a trap over a one year period.
This study made evident that: i) Sponge spicules represent the main component of the BSi both in the sediments and in the trapped matter; ii) A correlation exists between the sponge biomass present on the overhanging cliff and the amount of sponge spicules found in the sediment below; iii) Inside the sediments, a superficial layer (10 cm deep) characterized by intensive silica dissolution processes can be observed; and iv) The amount of spicules collected using the trap is not constant throughout the year, but shows a characteristic trend with low values in spring and summer and high values in autumn and winter.  相似文献   

Assumption and elimination of trace elements in Adélie penguins from Antarctica: a preliminary study     

Ancora S  Volpi V  Olmastroni S  Focardi S  Leonzio C 《Marine environmental research》2002,54(3-5):341-344

The concentration and distribution of some trace elements were determined in stomach contents, excreta and feathers of Adélie penguins (Pygoscelis adeliae) breeding at Edmonson Point (Terra Nova Bay-Antarctica). In these materials obtained by non-destructive methods, concentrations of mercury, cadmium and lead measured were used to establish natural levels of these metals in the penguins' diet. An intake-excretion hypothesis was formulated.  相似文献   

Biomarkers of Exposure and Effects for Assessing Toxicological Risk of Endocrine Disrupters in Top Predators of the Mediterranean Sea     

M. Cristina Fossi  Silvia Casini  Letizia Marsili  Stefania Ancora  Gabriele Mori  Giovanni Neri  Antonella Ausili  Teresa Romeo  Alessandra Moscatelli  Giuseppe Notarbartolo Di  Sciara 《Marine Ecology》2002,23(S1):184-189

Abstract. Endocrine Disrupting Chemicals (EDCs) have the potential to alter hormone pathways that regulate reproductive processes in wildlife and fisheries. In this research the unexplored hypothesis that Mediterranean top predator species (such as large pelagic fish and marine mammals) are potentially at risk due to EDCs is investigated. In the Mediterranean environment, top predators accumulate high concentrations of polyhalogenated aromatic hydrocarbons (PHAHs) and toxic metals, incurring high toxicological risk. Here we illustrate the need to develop sensitive biomarkers for evaluation of toxicological risk in top marine predators (Xiphias gladius, Thunnus thynnus thynnus) and non-lethal techniques, such as non-destructive biomarkers, for the hazard assessment of threatened species exposed to EDCs, such as marine mammals ( Stenella coeruleoalba, Tursiops truncatus, Delphinus delphis and Balaenoptera physalus ).  相似文献   

Prediction of ground displacements and velocities from groundwater level changes at the Vallcebre landslide (Eastern Pyrenees, Spain)   总被引：2，自引：5，他引：2  

Jordi Corominas  José Moya  Alberto Ledesma  Antonio Lloret  Josep A. Gili 《Landslides》2005,2(2):83-96

In active landslides, the prediction of acceleration of movement is a crucial issue for the design and performance of warning systems. The landslide of Vallcebre in the Eastern Pyreenes, Spain, has been monitored since 1996 and data on rainfall, groundwater levels and ground displacements are measured on a regular basis. Displacements observed in borehole wire extensometers have shown an immediate response of the landslide to rainfall episodes. This rapid response is likely due to the presence of preferential drainage ways. The occurrence of nearly constant rates of displacement in coincidence with steady groundwater levels suggests the presence of viscous forces developed during the movement. An attempt to predict both landslide displacements and velocities was performed at Vallcebre by solving the momentum equation in which a viscous term (Bingham and power law) was added. Results show that, using similar rheological parameters for the entire landslide, computed displacements reproduce quite accurately the displacements observed at three selected wire extensometers. These results indicate that prediction of displacements from groundwater level changes is feasible.  相似文献   

Acknowledgement of referees for Volume 77 (2015)     

Roberto Scandone  Stefania Bartolini  Joan Martí 《Bulletin of Volcanology》2016,78(1):1-19

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Characterization of volcanic thermal anomalies by means of sub-pixel temperature distribution analysis     

Valerio Lombardo  Maria Fabrizia Buongiorno  Stefania Amici 《Bulletin of Volcanology》2006,68(7-8):641-651

The simultaneous solution of the Planck equation (involving the widely used “dual-band” technique) using two shortwave infrared (SWIR) bands allows for an estimate of the fractional area of the hottest part of an active lava flow (f _h) and the background temperature of the cooler crust (T _c). The use of a high spectral and spatial resolution imaging spectrometer with a wide dynamic range of 15 bits (DAIS 7915) in the wavelength range from 0.501 to 12.67 μm resulted in the identification of crustal temperature and fractional areas for an intra-crater hot spot at Mount Etna, Italy. This study indicates the existence of a relationship between these T _c and f _h extracted from DAIS and Landsat TM data. When the dual band equation system is performed on a lava flow, a logarithmic distribution is obtained from a plot of the fractional area of the hottest temperature vs. the temperature of the cooler crust. An entirely different distribution is obtained over active degassing vents, where increases in T _c occur without any increase in f _h. This result indicates that we can use scatter plots of T _c vs. fh to discriminate between different types of volcanic activity, in this case between degassing vents and lava flows, using satellite thermal data.  相似文献   

Shallow landslides in deeply weathered slates of the Sierra de Collcerola (Catalonian Coastal Range, Spain)     

Domenico Calcaterra  Jos A. Gili  Roberto Iovinelli 《Engineering Geology》1998,50(3-4):283-298

Stability conditions in an area located NW of Barcelona (Spain) are discussed. Here, several mass movements were observed, mainly affecting weathered Paleozoic slates. Many of these failures involved slopes cut along recent infrastructures: debris flows, wedge and plane failures, generally surficial, occurred more frequently. After a detailed geological and geomorphologic survey, geomechanic characterization was carried out, according to RMR and SMR classifications. This rating gave a prediction of slope behaviour, in fairly good agreement with the real observed one.

Stability numerical analysis was carried out for the main cut slopes, based upon the Limit Equilibrium Method. First of all, the deterministic factor of safety was computed using the mean values of parameters. After that, a simulation technique based upon the Monte Carlo Method was applied in order to obtain factor of safety distributions. The probability of failure was estimated as P(F<1).

Finally, results from deterministic and probabilistic approaches were compared. The effectiveness of different possible remedial measures was highlighted by means of a sensitivity analysis, which showed that the more important parameters in the study area are the geometrical ones (height, slope and failure plane angles). The final technical solutions adopted are briefly outlined.  相似文献   

Study of temperature and precipitation variations in Italy based on surface instrumental observations   总被引：1，自引：0，他引：1  

Tiziano Colombo  Vinicio Pelino  Stefania Vergari  Paolo Cristofanelli  Paolo Bonasoni 《Global and Planetary Change》2007,57(3-4):308-318

In this paper we present a study concerning the climatic behaviour of two principal observables, temperature and precipitation as obtained from the measurements carried out at 50 Italian meteorological stations, since 1961. Analyses of WMO Climate Normals (CliNo) from 1961 to 1990 have been performed dividing the 50 Italian stations in three different classes: mountain (11 stations), continental (17) and coastal areas (21).The comparison of the CliNo 1961–1990 with the trend of temperature and precipitation for the period 1991–2000 showed a sharp significant increase of summer temperatures over Italy starting from 1980. This phenomenon was particularly evident for mountain stations, where a significant temperature increase has been recorded also during the autumn. Moreover, the analysis of precipitation data permitted to point out that, starting from 1980, mountain stations have been affected by a significant increase of precipitation events during autumn and winter, while for the rest of the Italian territory a reduction of precipitations has been recorded during early spring.  相似文献   

Cosmic stellar relics in the Galactic halo     

Stefania Salvadori  Raffaella Schneider  Andrea Ferrara 《Monthly notices of the Royal Astronomical Society》2007,381(2):647-662

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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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