Modelling seasonal variations of natural radioactivity in soils: A case study in southern Italy     

Ilaria Guagliardi  Natalia Rovella  Carmine Apollaro  Andrea Bloise  Rosanna De Rosa  Fabio Scarciglia  Gabriele Buttafuoco 《Journal of Earth System Science》2016,125(8):1569-1578

The activity of natural radionuclides in soil has become an environmental concern for local public and national authorities because of the harmful effects of radiation exposure on human health. In this context, modelling and mapping the activity of natural radionuclides in soil is an important research topic. The study was aimed to model, in a spatial sense, the soil radioactivity in an urban and peri-urban soils area in southern Italy to analyse the seasonal influence on soil radioactivity. Measures of gamma radiation naturally emitted through the decay of radioactive isotopes (potassium, uranium and thorium) were analysed using a geostatistical approach to map the spatial distribution of soil radioactivity. The activity of three radionuclides was measured at 181 locations using a high-resolution ?-ray spectrometry. To take into account the influence of season, the measurements were carried out in summer and in winter. Activity data were analysed by using a geostatistical approach and zones of relatively high or low radioactivity were delineated. Among the main processes which influence natural radioactivity such as geology, geochemical, pedological, and ecological processes, results of this study showed a prominent control of radio-emission measurements by seasonal changes. Low natural radioactivity levels were measured in December associated with winter weather and moist soil conditions (due to high rainfall and low temperature), and higher activity values in July, when the soil was dry and no precipitations occurred.  相似文献   

A new hybrid procedure for the definition of seismic vulnerability in Mediterranean cross-border urban areas     

Cavaleri  Liborio  Di Trapani  Fabio  Ferrotto  Marco Filippo 《Natural Hazards》2016,86(2):517-541

Assessment of seismic vulnerability of urban areas provides fundamental information for activities of planning and management of emergencies. The main difficulty encountered when extending vulnerability evaluations to urban contexts is the definition of a framework of assessment appropriate for the specific characteristics of the site and providing reliable results with a reasonable duration of surveys and post-processing of data. The paper proposes a new procedure merging different typologies of information recognized on the territories investigated and for this reason called “hybrid.” Knowledge of historical events influencing urban evolution and analysis of recurrent building technologies are used to evaluate the vulnerability indexes of buildings and building stocks. On the other hand, a vulnerability model is calibrated by means of experimental and numerical investigations on prototype buildings representative of the most recurrent typologies. In the final framework, the vulnerability index, calculated through simplified assessment forms, is linked to the seismic intensity expressed by the peak ground acceleration and associated with an index of damage expressing the economical loss. The procedure has been tested on the urban center of Lampedusa island (Italy) providing as the output vulnerability index maps, vulnerability curves, critical PGA maps, and estimation of the economical damage associated with different earthquake scenarios. The application of the procedure can be suitably repeated for medium-to-small urban areas, typically recurring in the Mediterranean by carrying out each time a recalibration of the vulnerability model.

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Characterization of spatial relationships between three remotely sensed indirect indicators of biodiversity and climate: a 21years' data series review across the Canadian boreal forest     

Liliana Perez  Trisalyn Nelson  Nicholas C. Coops  Fabio Fontana  C. Ronnie Drever 《International Journal of Digital Earth》2016,9(7):676-696

Climate drives ecosystem processes and impacts biodiversity. Biodiversity patterns over large areas, such as Canada's boreal, can be monitored using indirect indicators derived from remotely sensed imagery. In this paper, we characterized the historical space–time relationships between climate and a suite of indirect indicators of biodiversity, known as the Dynamic Habitat Index (DHI) to identify where climate variability is co-occurring with changes in biodiversity indicators. We represented biodiversity using three indirect indicators generated from 1987 to 2007 National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer images. By quantifying and clustering temporal variability in climate data, we defined eight homogeneous climate variability zones, where we then analyzed the DHI. Results identified unique areas of change in climate, such as the Hudson Plains, that explain significant variations in DHI. Past variability in temperatures and growing season index had a strong influence on observed vegetation productivity and seasonality changes throughout Canada's boreal. Variation in precipitation, for most of the area, was not associated with DHI changes. The methodology presented here enables assessment of spatial–temporal relationships between biodiversity and climate variability and characterizes distinctive zones of variation that may be used for prioritization and planning to ensure long-term biodiversity conservation in Canada.  相似文献   

Environmental magnetic record of Antarctic palaeoclimate from Eocene/Oligocene glaciomarine sediments, Victoria Land Basin   总被引：1，自引：0，他引：1  

Leonardo Sagnotti  Fabio Florindo  Kenneth L. Verosub  Gary S. Wilson  & Andrew P. Roberts 《Geophysical Journal International》1998,134(3):653-662

The onset of continent-wide glaciation in Antarctica is still poorly understood, despite being one of the most important palaeoclimatic events in the Cenozoic. The Eocene/Oligocene boundary interval has recently been recognized as a critical time for Antarctic climatic evolution, and it may mark the preglacial–glacial transition. Magnetic susceptibility, intensity of natural and artificial remanences, hysteresis parameters and magnetic anisotropy of the lower half (late Eocene/early Oligocene) of the CIROS-1 core (from McMurdo Sound, Antarctica) reveal alternating intervals of high and low magnetic mineral concentrations that do not correspond to lithostratigraphic units in the core. Pseudo-single-domain magnetite is the main magnetic mineral throughout the sequence, and sharp changes in magnetite concentration match changes in clay mineralogy beneath and at the Eocene/Oligocene boundary. The detrital magnetite originated from weathering of the Ferrar Group (which comprises basic extrusive and intrusive igneous rocks). Weathering processes and input of magnetite to the Victoria Land Basin were intense during periods when the Antarctic climate was warmer than today, but during intervals when the climate was relatively cool, chemical weathering of the Ferrar Group was suppressed and input of detrital magnetite to the Victoria Land Basin decreased. Our results also indicate that a cold and dry climate was not established in Antarctica until the Eocene/Oligocene boundary, with major ice sheet growth occurring at the early/late Oligocene boundary. Some earlier cold intervals are identified, which indicate that climate had begun to deteriorate by the middle/late Eocene boundary.  相似文献   

Paleomagnetic analysis of curved thrust belts reproduced by physical models     

Elisabetta Costa  Fabio Speranza   《Journal of Geodynamics》2003,36(5):633-654

This paper presents a new methodology for studying the evolution of curved mountain belts by means of paleomagnetic analyses performed on analogue models. Eleven models were designed aimed at reproducing various tectonic settings in thin-skinned tectonics. Our models analyze in particular those features reported in the literature as possible causes for peculiar rotational patterns in the outermost as well as in the more internal fronts. In all the models the sedimentary cover was reproduced by frictional low-cohesion materials (sand and glass micro-beads), which detached either on frictional or on viscous layers. These latter were reproduced in the models by silicone. The sand forming the models has been previously mixed with magnetite-dominated powder. Before deformation, the models were magnetized by means of two permanent magnets generating within each model a quasi-linear magnetic field of intensity variable between 20 and 100 mT. After deformation, the models were cut into closely spaced vertical sections and sampled by means of 1×1-cm Plexiglas cylinders at several locations along curved fronts. Care was taken to collect paleomagnetic samples only within virtually undeformed thrust sheets, avoiding zones affected by pervasive shear. Afterwards, the natural remanent magnetization of these samples was measured, and alternating field demagnetization was used to isolate the principal components. The characteristic components of magnetization isolated were used to estimate the vertical-axis rotations occurring during model deformation. We find that indenters pushing into deforming belts from behind form non-rotational curved outer fronts. The more internal fronts show oroclinal-type rotations of a smaller magnitude than that expected for a perfect orocline. Lateral symmetrical obstacles in the foreland colliding with forward propagating belts produce non-rotational outer curved fronts as well, whereas in between and inside the obstacles a perfect orocline forms only when the ratio between obstacles' distance and thickness of the cover is greater than 10. Finally, when a belt collides with an obstacle in the foreland oblique to the shortening direction the outer front displays rotations opposite in sign to oroclinal-type rotations, whereas the internal fronts seem to assume an “oroclinal type” rotational pattern. Furthermore rotation is easier in laterally unconfined models, i.e. when the wedge can “escape” laterally. The results from our models may be useful when compared to paleomagnetic rotations detected in natural arcs. In these cases, our results may allow for better understanding the tectonic setting controlling the genesis of curved mountain fronts, as is the case of the Gela Nappe of Sicily we compare with some of our models.  相似文献   

The Impact of Human Recreational Activities in Marine Protected Areas: What Lessons Should Be Learnt in the Mediterranean Sea?   总被引：2，自引：0，他引：2  

Marco Milazzo  Renato Chemello  Fabio Badalamenti  Raffaele Camarda  Silvano Riggio 《Marine Ecology》2002,23(S1):280-290

Abstract. The aesthetic appeal of marine reserves and the facilities provided, together with the increased public awareness of nature, all contribute to creating massive tourism in MPAs. Human activities are being changed inside MPAs in two ways: humans as top predators are generally being removed, but in turn they could come back at great numbers as visitors.
Many authors have studied the impact of visitors, and the results highlight that the consequences can be very substantial and may represent a severe threat to the overall diversity of marine communities. To date, the documented effects of human recreational activities on natural communities are restricted to assessing the consequences of trampling over intertidal and upper infralittoral areas, boat anchoring in seagrass meadows and tropical reefs, or SCUB A-diving.
In this paper we review the available literature world-wide on the effects of human recreational activities in marine communities. The objective is to address the extent of these impacts and to highlight the gaps of knowledge to be filled in order to optimise decision making on research, monitoring, and management of Mediterranean MPAs. A specific plan for managing tourism use in each Mediterranean MPA should be designated. These strategies should be implemented through education, training, and changes in legislation and policy.  相似文献   

Dynamical model of binary asteroid systems through patched three-body problems     

Fabio?FerrariEmail author  Michèle?Lavagna  Kathleen?C.?Howell 《Celestial Mechanics and Dynamical Astronomy》2016,125(4):413-433

The paper presents a strategy for trajectory design in the proximity of a binary asteroid pair. A novel patched approach has been used to design trajectories in the binary system, which is modeled by means of two different three-body systems. The model introduces some degrees of freedom with respect to a classical two-body approach and it is intended to model to higher accuracy the peculiar dynamical properties of such irregular and low gravity field bodies, while keeping the advantages of having a full analytical formulation and low computational cost required. The neighborhood of the asteroid couple is split into two regions of influence where two different three-body problems describe the dynamics of the spacecraft. These regions have been identified by introducing the concept of surface of equivalence (SOE), a three-dimensional surface that serves as boundary between the regions of influence of each dynamical model. A case of study is presented, in terms of potential scenario that may benefit of such an approach in solving its mission analysis. Cost-effective solutions to land a vehicle on the surface of a low gravity body are selected by generating Poincaré maps on the SOE, seeking intersections between stable and unstable manifolds of the two patched three-body systems.  相似文献   

The Hyblean xenolith suite (Sicily): an unexpected legacy of the Ionian–Tethys realm     

Fabio Carmelo Manuella  Vittorio Scribano  Serafina Carbone  Alfonso Brancato 《International Journal of Earth Sciences》2015,104(5):1317-1336

The extensive study of a great number of deep-seated xenoliths from Tortonian tuff-breccia pipes in the Hyblean area (Sicily) revealed the following fundamental evidence: (1) typical continental crust rocks are completely absent in the entire xenolith suite; (2) mantle ultramafics are more abundant than gabbroids; (3) sheared oxide–gabbros, closely resembling those from oceanic fracture zones, are relatively common; (4) secondary mineral assemblages, compatible with alteration processes in serpentinite-hosted hydrothermal systems, occur both in peridotites and gabbros. Among the products of this hydrothermal activity, organic compounds, having abiotic origin via Fischer–Tropsch synthesis, occur in some hydrothermally altered gabbro and ultramafic xenoliths, as well as in hydrothermal clays. Moreover, the U–Pb dating of hydrothermal zircon grains, hosted in a xenolith of metasomatized tectonic breccia, indicated an Early–Middle Triassic age of the fossil hydrothermal system. Another line of evidence for the oceanic nature of the Hyblean–Pelagian basement is the complete absence of continental crust lithologies (granites, felsic metaigneous, and metasedimentary rocks) in outcrops and in boreholes, and the oceanic affinity of the Tertiary volcanic rocks from the Hyblean Plateau and the Sicily Channel (Pantelleria and Linosa Islands), which lack of any geochemical signature for continental crust contamination. A reappraisal of existing geophysical data pointed out that serpentinites form the dominant lithologies in the lithospheric basement of the Hyblean–Pelagian area down to a mean depth of 19 km, which represents the regional Moho considered as the serpentinization front, marking the transition from serpentinites to unaltered peridotites. On these grounds, we confirm that Hyblean xenoliths contain mineralogical, compositional, and textural evidence for tectonic, magmatic, and hydrothermal processes indicating the existence of fossil oceanic core complexes, in the geotectonic framework of the Paleo–Mesozoic, ultra-slow spreading, Ionian–Tethys Ocean forming the present Ionian–Hyblean–Pelagian domain.  相似文献   

On the efficiency and effectiveness of automatic deep drainage systems during an extreme rainfall event: the Mendatica landslide case study (western Liguria,Italy)     

Pepe  Giacomo  Cevasco  Andrea  Piazza  Michele  Macciò  Roberto  Arrighetti  Fabio  Casagli  Nicola 《Landslides》2021,18(12):3799-3820

Landslides - This study presents the employment of automatic deep drainage systems to stabilize the Mendatica landslide, one of the largest relict landslides of western Liguria (north-western...  相似文献   

A geophysical perspective on the lithosphere–asthenosphere system beneath the Qinghai–Tibet Plateau and adjacent areas     

Fabio Romanelli 《《地质学报》英文版》2018,92(Z1):260-260

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