The Sponge Community of a Semi-Submerged Mediterranean Cave   总被引：1，自引：0，他引：1  

Giuseppe Corriero  Lidia Scalera Liaci  Daniela Ruggiero  & Maurizio Pansini 《Marine Ecology》2000,21(1):85-96

Abstract. The sponge fauna of a semi-submerged cave from the Tremiti Archipelago (Adriatic Sea) was studied, and its distribution was analyzed in relation to abiotic (water-movement and light gradients) and biotic (algae and anthozoan substrate cover) ecological factors. Fifty-five species of sponges were recorded. The number of species and the abundance values of sponges increase in the first part of the cave, then progressively decrease, with a sharp fall at the end of the cave. The quick disappearance of algae along the light gradient allows sponges to thrive in the first portion of the cave. The subsequent, progressive decrement of sponges could be the result of food depletion phenomena due to a long persistence of the water body in this long cavity. A high water-turbulence, due to the peculiar morphology of the cave and indicated by the recorded values of water-movement, occurs at the end of the cavity and probably determines the sharp decrement of sponges in the inner portion of the cave. This turbulence may also explain the absence of typical still-water cave species and probably affects the type of development (shape, overgrowth) of the sponges in the community.  相似文献   

Spatial variability of phytoplankton, nutrients and new production estimates in the waters around Svalbard   总被引：3，自引：0，他引：3  

Georgina Owrid  Giorgio Socal  Giuseppe Civitarese  Anna Luchetta  Jozef Wiktor  Eva-Maria Nöthig  Inger Andreassen  Ursula Schauer  Volker Strass 《Polar research》2000,19(2):155-171

Phytoplankton dynamics and carbon input into Arctic and sub-Arctic ecosystems were investigated around Svalbard, in summer 1991. Phytoplankton biomass, species composition and dissolved nutrient concentrations were analysed from water samples collected along seven transects. Phytoplankton biomass was low especially to the north (Chlorophyll-a mean 0.3 pg 1- '), where flagellates dominated the communities and only ice-diatoms were present. To the west, the phytoplankton composition was representative of a summer Atlantic community, in a post-bloom state. Zooplankton grazing, mainly by copepods, appeared to be the main control on biomass to the west and north of Svalbard.
In the Barents Sea (east of Svalbard), an ice edge bloom was observed (Chlorophyll-a max. 6.8 pgl-') and the ice edge receded at a rate of approximately 1 1 km day-'. The phytoplankton community was represented by marginal ice species, especially Phaeocystis poucherii and Chaeroceros socialis. South of the ice edge, Deep Chlorophyll Maxima (DCM) were observed, as surface waters became progressively nutrient-depleted. In these surface waters, the phytoplankton were predominantly auto- and heterotrophic flagellates.
Carbon production measurements revealed high net production (new and regenerated) to the north of the Barents Sea Polar Front (BSPF); it was especially high at the receding ice edge (reaching 1.44gC m-'day-'). To the south, a low level of production was maintained, mainly through regenerative processes.  相似文献   

Effects of cluster galaxies on arc statistics     

Massimo Meneghetti  Micol Bolzonella  Matthias Bartelmann  Lauro Moscardini  Giuseppe Tormen 《Monthly notices of the Royal Astronomical Society》2000,314(2):338-347

We present the results of a set of numerical simulations evaluating the effect of cluster galaxies on arc statistics.
We perform a first set of gravitational lensing simulations using three independent projections for each of nine different galaxy clusters obtained from N -body simulations. The simulated clusters consist of dark matter only. We add a population of galaxies to each cluster, mimicking the observed luminosity function and the spatial galaxy distribution, and repeat the lensing simulations including the effects of cluster galaxies, which themselves act as individual lenses. Each galaxy is represented by a spherical Navarro, Frenk & White density profile.
We consider the statistical distributions of the properties of the gravitational arcs produced by our clusters with and without galaxies. We find that the cluster galaxies do not introduce perturbations strong enough to significantly change the number of arcs and the distributions of lengths, widths, curvature radii and length-to-width ratios of long arcs. We find some changes to the distribution of short-arc properties in the presence of cluster galaxies. The differences appear in the distribution of curvature radii for arc lengths smaller than 12 arcsec, while the distributions of lengths, widths and length-to-width ratios are significantly changed only for arcs shorter than 4 arcsec.  相似文献   

A coupled MFE poromechanical model of a large-scale load experiment at the coastland of Venice     

Nicola Castelletto  Giuseppe Gambolati  Pietro Teatini 《Computational Geosciences》2015,19(1):17-29

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Global and regional ocean carbon uptake and climate change: sensitivity to a substantial mitigation scenario   总被引：1，自引：0，他引：1  

Marcello Vichi  Elisa Manzini  Pier Giuseppe Fogli  Andrea Alessandri  Lavinia Patara  Enrico Scoccimarro  Simona Masina  Antonio Navarra 《Climate Dynamics》2011,37(9-10):1929-1947

Under future scenarios of business-as-usual emissions, the ocean storage of anthropogenic carbon is anticipated to decrease because of ocean chemistry constraints and positive feedbacks in the carbon-climate dynamics, whereas it is still unknown how the oceanic carbon cycle will respond to more substantial mitigation scenarios. To evaluate the natural system response to prescribed atmospheric ??target?? concentrations and assess the response of the ocean carbon pool to these values, 2 centennial projection simulations have been performed with an Earth System Model that includes a fully coupled carbon cycle, forced in one case with a mitigation scenario and the other with the SRES A1B scenario. End of century ocean uptake with the mitigation scenario is projected to return to the same magnitude of carbon fluxes as simulated in 1960 in the Pacific Ocean and to lower values in the Atlantic. With A1B, the major ocean basins are instead projected to decrease the capacity for carbon uptake globally as found with simpler carbon cycle models, while at the regional level the response is contrasting. The model indicates that the equatorial Pacific may increase the carbon uptake rates in both scenarios, owing to enhancement of the biological carbon pump evidenced by an increase in Net Community Production (NCP) following changes in the subsurface equatorial circulation and enhanced iron availability from extratropical regions. NCP is a proxy of the bulk organic carbon made available to the higher trophic levels and potentially exportable from the surface layers. The model results indicate that, besides the localized increase in the equatorial Pacific, the NCP of lower trophic levels in the northern Pacific and Atlantic oceans is projected to be halved with respect to the current climate under a substantial mitigation scenario at the end of the twenty-first century. It is thus suggested that changes due to cumulative carbon emissions up to present and the projected concentration pathways of aerosol in the next decades control the evolution of surface ocean biogeochemistry in the second half of this century more than the specific pathways of atmospheric CO₂ concentrations.  相似文献   

The Averno 2 fissure eruption: a recent small-size explosive event at the Campi Flegrei Caldera (Italy)   总被引：1，自引：0，他引：1  

Mauro Antonio Di Vito  Ilenia Arienzo  Giuseppe Braia  Lucia Civetta  Massimo D’Antonio  Valeria Di Renzo  Giovanni Orsi 《Bulletin of Volcanology》2011,73(3):295-320

The Averno 2 eruption (3,700 ± 50 a B.P.) was an explosive low-magnitude event characterized by magmatic and phreatomagmatic explosions, generating mainly fall and surge beds, respectively. It occurred in the Western sector of the Campi Flegrei caldera (Campanian Region, South Italy) at the intersection of two active fault systems, oriented NE and NW. The morphologically complex crater area, largely filled by the Averno lake, resulted from vent activation and migration along the NE-trending fault system. The eruption generated a complex sequence of pyroclastic deposits, including pumice fall deposits in the lower portion, and prevailing surge beds in the intermediate-upper portion. The pyroclastic sequence has been studied through stratigraphical, morphostructural and petrological investigations, and subdivided into three members named A through C. Member A was emplaced during the first phase of the eruption mainly by magmatic explosions which generated columns reaching a maximum height of 10 km. During this phase the eruption reached its climax with a mass discharge rate of 3.2 10⁶ kg/s. Intense fracturing and fault activation favored entry of a significant amount of water into the system, which produced explosions driven by variably efficient water-magma interaction. These explosions generated wet to dry surge deposits that emplaced Member B and C, respectively. Isopachs and isopleths maps, as well as areal distribution of ballistic fragments and facies variation of surge deposits allow definition of four vents that opened along a NE oriented, 2 km long fissure. The total volume of magma extruded during the eruption has been estimated at about 0.07 km³ (DRE). The erupted products range in composition from initial, weakly peralkaline alkali-trachyte, to last-emplaced alkali-trachyte. Isotopic data and modeling suggest that mixing occurred during the Averno 2 eruption between a more evolved, less radiogenic stored magma, and a less evolved, more radiogenic magma that entered the shallow reservoir to trigger the eruption. The early phases of the eruption, during which the vent migrated from SW to the center of the present lake, were fed by the more evolved, uppermost magma, while the following phases extruded the less evolved, lowermost magma. Integration of the geological and petrological results suggests that the Averno 2 complex eruption was fed from a dyke-shaped shallow reservoir intruded into the NE-SW fault system bordering to the west the La Starza resurgent block, within the caldera floor.  相似文献   

SWASV speciation of Cd, Pb and Cu for the determination of seawater contamination in the area of the Nicole shipwreck (Ancona coast, Central Adriatic Sea)     

Annibaldi A  Illuminati S  Truzzi C  Scarponi G 《Marine pollution bulletin》2011,62(12):2813-2821

The study reports for the first time on the heavy metal contamination of the waters surrounding a shipwreck lying on the sea floor. Square wave anodic stripping voltammetry has been used for a survey of the total and dissolved Cd, Pb and Cu contents of the seawater at the site of the sinking of the Nicole M/V (Coastal Adriatic Sea, Italy). Results show that the hulk has a considerable impact as regards all three metals in the bottom water, especially for the particulate fraction concentrations, which increased by factors of ∼9 (Cd), ∼3 (Pb) and ∼5 (Cu). The contaminated plume extended downstream for about 2 miles. Much lower contamination was observed for dissolved bottom concentrations; nevertheless Pb (0.56 ± 0.03 nmol/L) is higher than the Italian legal limits established for 2015 and Cd (0.23 ± 0.03 nmol/L) is very close the limit of Cd will be exceeded if the hulk is not removed.  相似文献   

Time and duration of Variscan high-temperature metamorphic processes in the south European Variscides: constraints from U-Pb chronology and trace element chemistry of zircon   总被引：1，自引：0，他引：1  

Annamaria Fornelli  Antonio Langone  Francesca Micheletti  Giuseppe Piccarreta 《Mineralogy and Petrology》2011,103(1-4):101-122

The lower crust of the Serre massif (Calabria, southern Italy) provides a window into the mid- to lower crust of the south European Variscan orogenic belt. Previously, zircon U-Pb ages were employed to date high-temperature processes affecting this portion of the Variscan crust. The present paper reports new LA-ICP-MS U-Pb data on the zircon of a deformed quartz-monzodiorite dike and of three mafic granulites sampled at the base of the lower crust section. Determination of trace elements on zircon, including rare earth elements (REE), has been also performed. The end of the Variscan exhumation, dated by anatectic zircon from migmatitic metapelites, and the growth-modification of zircon with respect to the growth of Variscan metamorphic garnet have been assumed as ??time markers??. The concordant zircon ages of the metamorphic basic rocks cover a range from 744?±?20 Ma to 231?±?10 Ma with high age density from 357?±?11?Ma to 279?±?10 Ma, a few ages comprised between 418?±?14 Ma and 483?±?12 Ma and between 505?±?11 Ma and 593?±?14 Ma. Zircon from the deformed quartz-monzodiorite dike evidences a minimum age of emplacement of 323?±?5 Ma. Most of the analysed zircon domains dated between 357?±?11 Ma to 279?±?10 Ma from garnet-bearing metabasic rocks show flat patterns of heavy rare earth elements (HREE), as expected in the case of their simultaneous growth with garnet. This allows to consider (1) zircon domains giving Variscan ages as ??metamorphic?? with specific geological significance, and (2) zircon domains with ages ranging from 564?±?17 Ma to 593?±?14 Ma as dating the emplacement of the magmatic protoliths as shown by internal microtextures, fractionated patterns of HREE and Th/U ratios (0.16?C0.19). The Variscan zircon ages (357?C279?Ma) reflect effects of crustal thickening, peak metamorphism and subsequent multistage Variscan decompression documented by the statistically significant clusters of ages around 347?C340?Ma, 323?C318?Ma, 300?C294?Ma and 279?Ma. The U-Pb zircon ages of the metabasic rocks suggest a period of about 60?C70?Ma for granulite facies metamorphism and anatectic conditions. Literature data indicate that the migmatitic metapelites of the upper part of the Serre crust section also underwent a long period, about 40?Ma, of granulite facies metamorphism and anatectic conditions. A diachronism emerges through the time comparison of the Variscan evolution between the upper and the lower portions of the Serre deep crust. The duration of the Variscan processes defined in Calabria is comparable to that of other south European Variscan blocks.  相似文献   

Relating Mean Radiosounding Profiles to Surface Fluxes for the Very Stable Boundary Layer     

L. Caporaso  A. Riccio  F. Di Giuseppe  F. Tampieri 《Boundary-Layer Meteorology》2013,147(2):203-215

A dataset collected during a measurement campaign in the middle of the Po Valley, Italy, is used to investigate the boundary-layer structure in stable conditions. Empirical formulations for temperature and wind profiles derived from Monin–Obukhov similarity theory are used as regression curves to fit radiosounding profiles in the lower half of the boundary-layer. The best fitting parameters of the regression are then compared to the surface turbulent fluxes as measured by a co-located sonic anemometer. This comparison shows significant discrepancies and supports earlier results showing that surface fluxes, in the limit of high stability, are not adequate scalings for mean profiles. The most evident differences are found for cases for which the bulk Richardson number turns out to be quite large. One of the practical consequences is that boundary-layer height diagnostic formulations that mainly rely on surface fluxes are in disagreement with those obtained by inspecting the thermodynamic profiles recorded during the radiosounding ascent. Moreover the incorrect scaling of similarity profiles in stable conditions leads to the erroneous diagnosis of 2-m air temperatures used in numerical weather prediction validation.  相似文献   

Functional clustering for Italian climate zones identification     

E. Di Giuseppe  G. Jona Lasinio  S. Esposito  M. Pasqui 《Theoretical and Applied Climatology》2013,114(1-2):39-54

This work presents a functional clustering procedure applied to meteorological time series. Our proposal combines time series interpolation with smoothing penalized B-spline and the partitioning around medoids clustering algorithm. Our final goal is to obtain homogeneous climate zones of Italy. We compare this approach to standard methods based on a combination of principal component analysis and Cluster Analysis (CA) and we discuss it in relation to other functional clustering approaches based on Fourier analysis and CA. We show that a functional approach is simpler than the standard methods from a methodological and interpretability point of view. Indeed, it becomes natural to find a clear connection between mathematical results and physical variability mechanisms. We discuss how the choice of the basis expansion (splines, Fourier) affects the analysis and propose some comments on their use. The basis for classification is formed by monthly values of temperature and precipitation recorded during the period 1971–2000 over 95 and 94 Italian monitoring stations, respectively. An assessment based on climatic patterns is presented to prove the consistency of the clustering and a comparison of results obtained with different methods is used to judge the functional data approach.  相似文献