Search results for "Ocean"
showing 10 items of 2919 documents
Ba/Ca evolution in water masses of the Mediterranean late Neogene
2008
[1] A Mediterranean composite sedimentary record was analyzed for Ba/Ca ratios on carbonate shells of Orbulina universa planktonic foraminifer (Ba/Ca)carb providing the opportunity to study and assess the extent of freshwater inputs on the basin and possible impacts on its dynamics during the Tortonian to Recent period. A number of scanning electron microscope analyses and auxiliary trace element measurements (Mn, Sr, and Mg), obtained from the same samples, exclude important diagenetic effects on the studied biogenic carbonates and corroborate the reliability of (Ba/Ca)carb ratios in foraminifera calcite as indicators of seawater source components during the studied interval. A long-term t…
HIGH-RESOLUTION PALAEONVIRONMENTAL RECONSTRUCTION OF ODP HOLE 963D (SICILY CHANNEL) DURING THE LAST DEGLACIATION BASED ON CALCAREOUS NANNOFOSSILS
2004
Abstract A palaeoenvironmental reconstruction of Ocean Drilling Program (ODP) Hole 963D (Sicily Channel) has been obtained on the basis of quantitative abundance fluctuations in the calcareous nannofossil assemblages. The studied hole is characterized by a very high sedimentary resolution and covers the last ca. 20 kyr. A new palaeoclimatic curve, based on the Gephyrocapsa muellerae/Upper Photic Zone (UPZ) group ratio, permitted the detection of the rapid climatic fluctuations that characterized the last deglaciation. Cold water masses occupied the Sicily Channel during the glacial period and the Younger Dryas, whereas they were generally warm during the Bolling–Allerod and the Holocene. An…
Comprehensive dataset of shotgun metagenomes from oxygen stratified freshwater lakes and ponds
2021
Stratified lakes and ponds featuring steep oxygen gradients are significant net sources of greenhouse gases and hotspots in the carbon cycle. Despite their significant biogeochemical roles, the microbial communities, especially in the oxygen depleted compartments, are poorly known. Here, we present a comprehensive dataset including 267 shotgun metagenomes from 41 stratified lakes and ponds mainly located in the boreal and subarctic regions, but also including one tropical reservoir and one temperate lake. For most lakes and ponds, the data includes a vertical sample set spanning from the oxic surface to the anoxic bottom layer. The majority of the samples were collected during the open wate…
Linking the Molecular Signature of Heteroatomic Dissolved Organic Matter to Watershed Characteristics in World Rivers
2015
Large world rivers are significant sources of dissolved organic matter (DOM) to the oceans. Watershed geomorphology and land use can drive the quality and reactivity of DOM. Determining the molecular composition of riverine DOM is essential for understanding its source, mobility and fate across landscapes. In this study, DOM from the main stem of 10 global rivers covering a wide climatic range and land use features was molecularly characterized via ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). FT-ICR mass spectral data revealed an overall similarity in molecular components among the rivers. However, when focusing specifically on the contributi…
An Evaluation Matrix to Compare Computer Hydrological Models for Flood Predictions
2020
In order to predict and control the impacts of floods in torrents, it is important to verify the simulation accuracy of the most used hydrological models. The performance verification is particularly needed for applications in watersheds with peculiar climatic and geomorphological characteristics, such as the Mediterranean torrents. Moreover, in addition to the accuracy, other factors affect the choice of software by stakeholders (users, modellers, researchers, etc.). This study introduces a &ldquo
Guidelines proposal for a good and durable WEC design
2017
In this paper, preliminarily a proposal for design guidelines for a “good” design of wave energy converter is presented and successively a small scale prototype of a wave energy converter including the buoyant electrical generator, the power electronics equipment and a sea water electrolyzer is designed on the basis of these guidelines and presented.
Design of wave energy converter (WEC): A prototype installed in Sicily
2015
The purpose of this work is to describe a possibility of installation of a wave converter in Sicily, in the Mediterranean Sea. In this paper we present the design of buoyant electrical generator, in particular, wave linear permanent magnet generator which can make wave energy converted to electrical energy.
Environmental Impact Assessment (EIA) of Wave Energy Converter (WEC)
2015
The Environmental Impact Assessment (EIA) is an environmental management instrument implemented worldwide. In the last years the development of Wave Energy Converter (WEC) influenced environmental research to quantify impacts on marine life. In this paper we present a case study of EIA: a real application and study of device installed in Tirren Sea (near Castellammare — Sicily).
Caractérisation des tôles Fer-Silicium en régime dynamique pulsant
1992
Using a characterization method based on the Epstein's frame principle, we study the evolution of the magnetic and losses characteristics of NO Fe-Si sheets with respect to the fundamental frequency, the temperature and the wave front under time-variable sinusoidal or constant wave front trapezoidal magnetic flux density. At last, we modelise the evolution of the iron losses with respect to these parameters, except the temperature
Characterizing weld pool surfaces from polarization state of thermal emissions
2013
International audience; In this Letter, a vision-based remote sensing methodology is proposed to measure the topography of weld pool surfaces from one single view. Thermal radiations emitted by the hot liquid metal at a wavelength within the arc plasma blind spectral window are acquired by a wavefront division polarimetric system. The refractive index of the liquid metal and the topography of the weld pool surface are inferred from the polarimetric state of the thermal radiations.