Ostreopsis cf. ovata bloom in the northern Adriatic Sea during summer 2009: ecology, molecular characterization and toxin profile     

Accoroni S  Romagnoli T  Colombo F  Pennesi C  Di Camillo CG  Marini M  Battocchi C  Ciminiello P  Dell'Aversano C  Dello Iacovo E  Fattorusso E  Tartaglione L  Penna A  Totti C 《Marine pollution bulletin》2011,62(11):2512-2519

Intense blooms of the benthic dinoflagellate Ostreopsis cf. ovata have occurred in the northern Adriatic Sea since 2006. These blooms are associated with noxious effects on human health and with the mortality of benthic organisms because of the production of palytoxin-like compounds. The O. cf. ovata bloom and its relationships with nutrient concentrations at two stations on the Conero Riviera (northern Adriatic Sea) were investigated in the summer of 2009. O. cf. ovata developed from August to November, with the highest abundances in September (1.3 × 10⁶ cells g⁻¹ fw corresponding to 63.8 × 10³ cells cm⁻²). The presence of the single O. cf. ovata genotype was confirmed by a PCR assay. Bloom developed when the seawater temperature was decreasing. Nutrient concentrations did not seem to affect bloom dynamics. Toxin analysis performed by high resolution liquid chromatography-mass spectrometry revealed a high total toxin content (up to 75 pg cell⁻¹), including putative palytoxin and all the ovatoxins known so far.  相似文献   

Performance of the Italian strong motion network during the 2009, L��Aquila seismic sequence (central Italy)     

Elisa Zambonelli  Rita de Nardis  Luisa Filippi  Mario Nicoletti  Mauro Dolce 《Bulletin of Earthquake Engineering》2011,9(1):39-65

On April 6, 2009, the town of L’Aquila in the Abruzzo region (central Italy) was struck by a seismic event at 01:32 (UTC), of magnitude M_W = 6.3. The mainshock was followed by a long period of intense seismic activity and within seven days after the mainshock there were seven events of magnitude M_W ≥ 5 that occurred from April 6 to April 13. This long seismic sequence was characterized by a complex rupture mechanism that involved two major normal faults of the central Apennines: the Paganica and the Gorzano faults. The strong-motions of the mainshock were recorded by 64 stations of the Italian Strong-motion Network (RAN) operated by the National Civil Protection Department (DPC). Six stations of a local strong-motion array were working in NW L’Aquila suburb area. One of them, located at about 6 km from the Paganica fault surface tip-line, set up in trigger mode, recorded continuously for more than 20 min the mainshock and the aftershocks. Besides the mainshock, the RAN stations recorded in total 78 foreshocks and aftershocks of M_L ≥ 3.5, during the period from January to December 2009. The corresponding waveforms provide the most extensive digital strong ground motion data set ever recorded in Italy. Moreover, the 48 three-component observations of events of magnitude M_W ≥ 5, recorded at a distance less than 15 km from each of the major involved faults, provide a significant increasing of near-field records available for the Italian territory. Six days after the mainshock, the strong-motion dataset, referred to preliminary locations of the events with M_L ≥ 4.0, was made available on the DPC web site () and at the same time it was delivered to the ITACA database (). This dataset has been used by many authors in scientific papers and by engineers, geophysicists and geologists for professional technical works. In this paper, the present-day available strong-motion signals from the L’Aquila sequence and the performance of the Italian strong-motion network in terms of the number and quality of recorded data, the geometry and data transmission system are described. In addition the role of the temporary network that represents an extension of the permanent Italian strong-motion network, supporting the emergency response by civil protection authorities and improving the network coverage has been evaluated.  相似文献   

Magnetic properties and cation ordering of nanopowders of the synthetic analogue of kuramite, Cu3SnS4     

Francesco Di Benedetto  Daniele Borrini  Andrea Caneschi  Gabriele Fornaciai  Massimo Innocenti  Alessandro Lavacchi  Carlo Andrea Massa  Giordano Montegrossi  Werner Oberhauser  Luca A. Pardi  Maurizio Romanelli 《Physics and Chemistry of Minerals》2011,38(6):483-490

An extensive characterisation of the magnetic properties of synthetic powders of kuramite, with formal composition Cu₃SnS₄, was performed. Powders were investigated through superconducting quantum interference device (SQUID) magnetometry, electron paramagnetic resonance (EPR) spectroscopy, X-ray powder diffraction (XRPD), scanning and transmission electron microscopies (SEM and TEM) and microanalysis. SEM and TEM reveal the presence of nanodimensioned particles. XRPD clearly shows that Cu₃SnS₄ crystallised in a cubic sphalerite-type structural model, in spite of the stannite-type tetragonal structure described for the natural phase. This difference arises from a full random distribution of cations. Synthetic kuramite nanopowders exhibit a marked paramagnetism, originated by the presence of Cu(II), definitely assessed by EPR measurements. Moreover, the overall magnetic behaviour of the sample cannot be simply ascribed to diluted paramagnetism, and this suggests the presence of strong superexchange interactions among Cu(II) ions even at room temperature. The main consequences of these results are the definitive assessment of the chemical formula Cu(I)₂Cu(II)SnS₄ and of a random distribution of Cu(II), Cu(I) and Sn(IV) ions within the available tetrahedral sites.  相似文献   

A note on modeling double diffusive mixing in the global ocean     

Lakshmi Kantha  Sandro Carniel  Mauro Sclavo 《Ocean Modelling》2011,36(1-2):40-48

Though ubiquitous in the global oceans, double diffusive mixing has been largely ignored or poorly represented in the models of turbulent mixing in the ocean and in 3-D ocean models, until recently. Salt fingers occur in the interior of many marginal seas and ocean basins, the Tyrrhenian Sea and the subtropical Atlantic being two examples. Diffusive convection type of double diffusion occurs in the upper layers of many sub-polar seas and polar oceans due to cold melt water from sea ice. Consequently, it is important to be able to properly parameterize double diffusive mixing in basin scale and global ocean models, so that the water mass structure in the interior of the ocean can be properly simulated. This note describes a model for double diffusive mixing in the presence of background shear, based on Mellor–Yamada type second moment closure, more specifically Kantha, 2003, Kantha and Clayson, 2004 second moment closure models of resulting turbulence, following Canuto et al. (2008a) but employing a different strategy for modeling the pertinent terms in the second moment equations. The resulting model is suitable for inclusion in ocean general circulation models.  相似文献   

Tsunami risk reduction for densely populated Southeast Asian cities: analysis of vehicular and pedestrian evacuation for the city of Padang, Indonesia, and assessment of interventions     

Manuela Di Mauro  Kusnowidjaia Megawati  Veronica Cedillos  Brian Tucker 《Natural Hazards》2013,68(2):373-404

A major tsunamigenic earthquake is expected in the near future along the coast of West Sumatra Province of Indonesia. In the city of Padang, the arrival time of the tsunami is expected to be ~30 min. Currently, there are approximately 400,000 people in the city living within the potential inundation zone. This study aimed to complement the existing research in appraising possible risk reduction interventions, specifically looking at enabling the timely evacuation of the area. This research, developed in consultation with national and local authorities, emergency planners and NGOs, analysed interventions for tsunami risk reduction in Padang through the development of a pedestrian and vehicular evacuation model and the appraisal of possible solutions to enhance the evacuation rates. Some of the conclusions from this research can be applied to other areas in Southeast Asia where the traffic patterns are similar to those in Padang and where the distance to safety is greater than 4–5 km. For the case of Padang, the results show that pedestrian evacuation is strongly preferable to vehicular evacuation due to the limited road capacity and the high population density. In the present situation, however, 70–80 % of the population in Padang could not evacuate within 30 min, even by foot. Common interventions such as widening roads and building bridges prove to be relatively ineffective in this case due to the large distance that has to be covered in a short time. These interventions would only have a decisive impact if a longer evacuation time was available (more than 60 min). In the case of Padang, the evacuation rate in the first 30 min is strongly dependent on the presence/absence of evacuation shelters, whose effectiveness is limited by the capacity of the structures. Building a few high-capacity and high-resilience structures such as evacuation hills is a more effective and robust evacuation strategy than constructing many small high-raised buildings. Even with evacuation structures, wider roads and bridges, about 20 % of the population would still be unable to reach safety by the time the tsunami arrives. This means about 70,000 people of Padang’s current population, which is rapidly increasing. The building of evacuation shelters may be a viable option for saving lives in the short term, but it is not a sustainable option in the medium to long term. It is therefore also necessary to set up and enforce regulations for land use planning that take into account the tsunami risk and prevent further urban development for the areas that may be affected by a tsunami.  相似文献   

Impact of single inclined faults on the fluid flow and heat transport: results from 3-D finite element simulations   总被引：1，自引：1，他引：0  

Yvonne Cherubini  Mauro Cacace  Guido Blöcher  Magdalena Scheck-Wenderoth 《Environmental Earth Sciences》2013,70(8):3603-3618

The impact of inclined faults on the hydrothermal field is assessed by adding simplified structural settings to synthetic models. This study is innovative in carrying out numerical simulations because it integrates the real 3-D nature of flow influenced by a fault in a porous medium, thereby providing a useful tool for complex geothermal modelling. The 3-D simulations for the coupled fluid flow and heat transport processes are based on the finite element method. In the model, one geological layer is dissected by a dipping fault. Sensitivity analyses are conducted to quantify the effects of the fault’s transmissivity on the fluid flow and thermal field. Different fault models are compared with a model where no fault is present to evaluate the effect of varying fault transmissivity. The results show that faults have a significant impact on the hydrothermal field. Varying either the fault zone width or the fault permeability will result in relevant differences in the pressure, velocity and temperature field. A linear relationship between fault zone width and fluid velocity is found, indicating that velocities increase with decreasing widths. The faults act as preferential pathways for advective heat transport in case of highly transmissive faults, whereas almost no fluid may be transported through poorly transmissive faults.  相似文献   

Presence and origin of polycyclic aromatic hydrocarbon in sediments of nine coastal lagoons in central Vietnam     

Giuliani S  Sprovieri M  Frignani M  Cu NH  Mugnai C  Bellucci LG  Albertazzi S  Romano S  Feo ML  Marsella E  Nhon DH 《Marine pollution bulletin》2008,56(8):1504-1512

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Evidence for an abrupt climatic change at 8700 14C yr B.P. in rockshelters and caves of Gebel Qara (Dhofar‐Oman): Palaeoenvironmental implications     

Mauro Cremaschi  Fabio Negrino 《Geoarchaeology》2005,20(6):559-579

Geoarchaeological research on the sedimentary fill of rockshelters and caves in the Gebel Qara (Dhofar, Southern Oman) has revealed the onset of heavy rains at 8700 yr B.P. These rains, produced by strengthening of the Southwest monsoon, abruptly altered the dry environment dominant in the area since the Pleistocene‐Holocene transition. Comparison of cave fills from the southern and northern fringes of the Gebel Qara indicates that the monsoon effects were limited to the southern and central part of the mountain range, directly facing the sea, and did not penetrate into the Nejd Desert. © 2005 Wiley Periodicals, Inc.  相似文献   

Empirically-based modeling of spatial sampling uncertainties associated with rainfall measurements by rain gauges     

Gabriele Villarini  Witold F. Krajewski 《Advances in water resources》2008

In the quantitative evaluation of radar-rainfall products (maps), rain gauge data are generally used as a good approximation of the true ground rainfall. However, rain gauges provide accurate measurements for a specific location, while radar estimates represent areal averages. Because these sampling discrepancies could introduce noise into the comparisons between these two sensors, they need to be accounted for. In this study, the spatial sampling error is defined as the ratio between the measurements by a single rain gauge and the true areal rainfall, defined as the value obtained by averaging the measurements by an adequate number of gauges within a pixel. Using a non-parametric scheme, the authors characterize its full statistical distribution for several spatial (4, 16 and 36 km²) and temporal (15 min and hourly) scales.  相似文献   

Discriminating the long distance dispersal of fine ash from sustained columns or near ground ash clouds: The example of the Pomici di Avellino eruption (Somma-Vesuvius,Italy)     

Roberto Sulpizio  Rosanna Bonasia  Pierfrancesco Dellino  Mauro A. Di Vito  Luigi La Volpe  Daniela Mele  Giovanni Zanchetta  Laura Sadori 《Journal of Volcanology and Geothermal Research》2008

Ash samples from tephra layers correlated with the Pomici di Avellino (Avellino Pumice) eruption of Somma-Vesuvius were collected in distal archives and their composition and particle morphology investigated in order to infer their behaviour of transportation and deposition. Differences in composition and particle morphologies were recognised for ash particles belonging to the magmatic Plinian and final phreatomagmatic phases of the eruption. The ash particles were dispersed in opposite directions during the two different phases of the eruption, and these directions are also different from that of coarse-grained fallout deposits. In particular, ash generated during magmatic phase and injected in the atmosphere to form a sustained column shows a prevailing SE dispersion, while ash particles generated during the final phreatomagmatic phase and carried by pyroclastic density currents show a general NW dispersion. These opposite dispersions indicate an ash dispersal influenced by both high and low atmosphere dynamics. In particular, the magmatic ash dispersal was first driven by stratospheric wind towards NE and then the falling particles encountered a variable wind field during their settling, which produced the observed preferential SE dispersal. The wind field encountered by the rising ash clouds that accompanied the pyroclastic density currents of the final phreatomagmatic phase was different with respect to that encountered by the magmatic ash, and produced a NW dispersal. These data demonstrate how ash transportation and deposition are greatly influenced by both high and low atmosphere dynamics. In particular, fine-grained particles transported in ash clouds of small-scale pyroclastic density currents may be dispersed over distances and cover areas comparable with those injected into the stratosphere by Plinian, sustained columns. This is a point not completely addressed by present day mitigation plans in case of renewal of activity at Somma-Vesuvius, and can yield important information also for other volcanoes potentially characterised by explosive activity.  相似文献