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Pozzuolo di Lerici, Italy

Pezzutto P.,CNR Marine Science Institute
Coastal Engineering | Year: 2016

Second-order Stokes-like solution of the wavemaker problem involves the participation of first order evanescent modes to the generation of spurious free harmonics. The unwanted free potential, and the paddle signal needed to suppress it, must be evaluated through series summation which, up to now, have been considered non-convergent for certain wavemaker configurations. This paper presents a demonstration of the convergence of these series summation for the historically discarded configurations. Following previous works, the free harmonics second order transfer function can obtained in two different ways. This operation reveals that the two alternative solutions match only if the lateral boundary condition is properly described. In particular, the domain restriction of non-continuous paddle shapes must be represented through left-continuous step functions. Conversely, if the support is limited only adjusting the integration limits, or the unit step function is non-zero at the origin, one of the two methods leads to an incomplete formulation. © 2016 Source

Cozzi S.,CNR Marine Science Institute | Giani M.,National Institute of Oceanography and Applied Geophysics - OGS
Continental Shelf Research | Year: 2011

Runoff and nutrient transport by rivers were analysed in the Northern Adriatic continental shelf, in order to evaluate their interannual and multidecal variability, as well as their current contribution to determine freshwater and nutrient budgets in this marine region. During the years 2004-2007, the runoff in the basin (34.1-64.6km3yr-1) was highly imbalanced, being 84% of freshwater discharged along the western coast, because of the contributions of Po, Adige and Brenta rivers. In the northern and eastern sections of the coast, freshwater discharge by rivers was less important (10 and 6%, respectively), but not negligible in determining the oceanographic properties at sub-regional scales. The oscillations of the transport of biogenic elements (124-262×103tNyr-1 for TN, 72-136×103tNyr-1 for DIN, 4.5-11.1×103tPyr-1 for TP, 2.2-3.5×103tPyr-1 for PO4 and 104-196×103tSiyr-1 for SiO2) were strictly dependant to the differences in the annual runoff. A strong excess of N load in comparison to P load characterised all rivers, both in inorganic nutrient (DIN/PO4=37-418) and total (TN/TP=48-208) pools, particularly in the northern and eastern areas of the basin.The annual runoff showed significant oscillations for Po on multidecadal time scale, whereas a general decrease (-33%) was observed for the other N Adriatic rivers as the recent discharges were compared to those before the 1980s. During the dry years 2005-2007, a strong reduction of river water flows and nutrient loads was experienced by the N Adriatic ecosystem with respect to years characterised by medium-high regimes. An increased frequency of similar drought periods, due to ongoing climate changes or to a larger human usage of continental waters, would be easily able to significantly change the biogeochemistry of this basin. © 2011 Elsevier Ltd. Source

Taviani M.,CNR Marine Science Institute
Lecture Notes in Earth Sciences | Year: 2011

This paper is focused upon the Miocene-to-Recent deep-sea chemosynthetic ecosystems of the Mediterranean basin with emphasis on their metazoan associates. The life ingredients of this story are basically the "microbes" and the "metazoans", in particular molluscs, whose mutual interplay resulted in a superb variety of situations in response to geologic and oceanographic factors directing the production and availability of geofluids usable by microbial consortia. The astounding complexity and diversity of modern metazoan-bearing deep-sea ecosystems inhabiting the Mediterranean is a step of a long journey whose beginning dates back to more than 3 billion years ago and whose major events are resumed below. © 2011 Springer Berlin Heidelberg. Source

Argnani A.,CNR Marine Science Institute
Tectonophysics | Year: 2012

The polarity of subduction in the Corsica-Northern Apennine system is a long-debated issue. Models adopting an original W-dipping subduction and models preferring a flip in the polarity of subduction, from E-dipping to W-dipping present inconsistencies that are mainly due to the 2D approach. A new proposal is presented, using Late Cretaceous to Present-Day kinematic reconstructions of the Central Mediterranean. A wide oceanic embayment is required to the west of the Adriatic Promontory, to account for the Oligocene-Present calcalkaline volcanism and back-arc extension. This implies that the continental collision that originated the Alps s.s. could not continue SW-ward of Adria. The change in subduction polarity, going from the Alps, to the Apennines, is taken as on original feature since the beginning of convergence. Kinematic reconstructions show that the point where subduction polarity changes moved N-ward along the plate boundary, from Late Cretaceous to Eocene. As a result, areas that previously experienced the continental collision of the Adriatic Promontory were subsequently affected by the oceanic subduction of the Tethyan embayment. This sequence of events caused the collapse of Alpine Corsica and led to the opening of the Balearic back-arc basin.A similar kinematic evolution is ongoing in Taiwan, where the N-ward subduction of the Philippine Sea plate is progressively substituting the E-ward subduction of the Eurasian plate, causing the collapse of the orogen in northern Taiwan.The slivers of continental basement rocks that are encased within the uppermost nappe in Corsica have been interpreted as remnants of a microplate that collided with Corsica. Plate kinematics offers an alternative explanation, with these basement rocks being derived from the colliding Adriatic promontory during Paleocene-Eocene; the promontory then passed away laterally, allowing the juxtaposition of the Alpine belt of Corsica with the early Apennines. © 2012 Elsevier B.V. Source

Corinaldesi C.,Marche Polytechnic University | Corinaldesi C.,CNR Marine Science Institute
Proceedings. Biological sciences / The Royal Society | Year: 2014

Deep hypersaline anoxic basins (DHABs) of the Mediterranean Sea are among the most extreme ecosystems on Earth and host abundant, active and diversified prokaryotic assemblages. However, factors influencing biodiversity and ecosystem functioning are still largely unknown. We investigated, for the first time, the impact of viruses on the prokaryotic assemblages and dynamics of extracellular DNA pool in the sediments of La Medee, the largest DHAB found on Earth. We also compared, in La Medee and L'Atalante sediments, the diversity of prokaryotic 16S rDNA sequences contained in the extracellular DNA released by virus-induced prokaryotic mortality. We found that DHAB sediments are hot-spots of viral infections, which largely contribute to the release of high amounts of extracellular DNA. DNase activities in DHAB sediments were much higher than other extracellular enzymatic activities, suggesting that extracellular DNA released from killed prokaryotes can be the most suitable trophic resource for benthic prokaryotes. Preserved extracellular DNA pools, which contained novel and diversified gene sequences, were very similar between the DHABs but dissimilar from the respective microbial DNA pools. We conclude that the strong viral impact in DHAB sediments influences the genetic composition of extracellular DNA, which can preserve the signatures of present and past infections. Source

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