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Registros recuperados: 34
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Particle size specific magnetic properties across the Norwegian-Greenland Seas: Insights into the influence of sediment source and texture on bulk magnetic records ArchiMer
Hatfield, Robert G.; Wheeler, Benjamin H.; Reilly, Brendan T.; Stoner, Joseph S.; Housen, Bernard A..
We make fundamental observations of the particle size variability of magnetic properties from 71 core tops that span the southern Greenland and Norwegian Seas. These data provide the first detailed regional characterization of how bulk magnetic properties vary with sediment texture, sediment source, and sediment transport. Magnetic susceptibility (MS) and hysteresis parameters were measured on the bulk sediment and the five constituent sediment particle size fractions (clay, fine, medium, and coarse silt, and sand). The median MS value of the medium silt size fraction is ~3‐5 times higher than that of the sand and clay size fractions and results in a strong sensitivity of bulk MS to sediment texture. Hysteresis properties of the clay size fraction are...
Tipo: Text Palavras-chave: Northern Basaltic Province; Magnetic susceptibility; Nordic Seas; Magnetic grain size; Sediment source; Sediment transport.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00478/58998/61614.pdf
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Impact of natural (waves and currents) and anthropogenic (trawl) resuspension on the export of particulate matter to the open ocean Application to the Gulf of Lion (NW Mediterranean) ArchiMer
Ferre, B; De Madron, X; Estournel, C; Ulses, C; Le Corre, Gildas.
Modern sediment deposits on continental margins form a vast reservoir of particulate matter that is regularly affected by resuspension processes. Resuspension by bottom trawling on shelves with strong fishing activity can modify the scale of natural disturbance by waves and currents. Recent field data show that the impact of bottom trawls on fine sediment resuspension per unit surface is comparable with that of the largest storms. We assessed the impact of both natural and anthropogenic processes on the dispersal of riverborne particles and shelf sediments on the Gulf of Lion shelf. We performed realistic numerical simulations of resuspension and transport forced by currents and waves or by a fleet of bottom trawlers. Simulations were conducted for a...
Tipo: Text Palavras-chave: Mediterranean; Trawling; Fisheries; Shelf slope exchanges; Sediment transport; Sediment dynamics.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-4682.pdf
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Devenir de l'atrazine dans le bassin de Marennes-Oléron. Approche par la modélisation hydrodynamique, hydrosédimentaire et biogéochimique ArchiMer
Vanhoutte Brunier, Alice.
Atrazine is the most widely used herbicide on cultured areas. This pesticide is degraded during its transport in rivers and streams, to the coastal area. Marennes Oléron is the main french oyster farming area, receiving the fresh water from the Charente river and ail the drainage coming from the coastal cultivated marshlands. Agriculture is thus claimed to be responsible for shellfish mortality in the aquaculture area. To simulate the changing fate of atrazine in the environment, a modelling strategy has been selected. a) First, using a two-way hydrodynamic model developped by IFREMER, the atrazine dilution trail in the Marennes Oléron area was simulated.Combined with larvae bioassays of Crassostrea gigas (Japanese oyster), the results show atrazine rates...
Tipo: Text Palavras-chave: Produits phytosanitaires; Atrazine; Cycle biogéochimique; Modélisation; Dynamique sédimentaire; Vasières intertidales; Pesticides; Atrazine; Biogeochemical cycle; Models; Sediment transport; Intertidal muflats.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/00412/52312/53082.pdf
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Sediment and water movement in coastal embayments. ArchiMer
Collins, M.
The investigations described in this report relating to Swansea Bay and Thermaicos Bay demonstrate that processes which take place in embayments, particularly those concerned with water and sediment movement, representing only a constituent part of a much larger transport system.
Tipo: Text Palavras-chave: Coastal zone; Sediment transport; Tidal motion; Wave motion; Hydrodynamics; Bays; Water motion; Sediment movement.
Ano: 1985 URL: http://archimer.ifremer.fr/doc/1985/acte-1286.pdf
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A model of sediment transport under the influence of surface bioturbation: generalisation to the facultative suspension-feeder Scrobicularia plana ArchiMer
Orvain, Francis.
Flume experiments were designed to study how sediment erodibility was modified by the facultative suspension-feeder Scrobicularia plana living at different densities in sediment beds of various degrees of compaction. Two separate erosion phases were identified from the resuspension kinetics: (1) erosion of an unconsolidated surficial layer (i.e. fluff layer) and (2) the subsequent bed erosion. S. plana were found to influence both erosion phases: (1) erosion rates of the fluff layer were controlled by bioturbation activities, the extents of which were influenced by bivalve density and the degree of compaction of the sediments, and (2) critical thresholds of the subsequent bed erosion decreased as clam density increased, likely due to depressions in the...
Tipo: Text Palavras-chave: Resuspension; Model; Functional groups; Sediment transport; Bioturbation; Scrobicularia plana; Intertidal mudflat.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-3776.pdf
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Les embouchures mésotidales (tidal inlets) et leur relation avec les littoraux adjacents - Exemple de la Barra Nova, Sud Portugal ArchiMer
Balouin, Yann.
Tidal inlets are among the most dynamic morphological features along the world coastlines. Their evolution and stability, frequently critical to the local environment, are dependent on the relative influence of longshore transport along adjacent coasts and tidal flows in the inlet. Main objective of this study was to quantify the processes involved in the inlet morphodynamics in order to determine the key parameters of these systems and to predict medium to long-term evolution. Morphology evolution (bathymetry, remote sensed video data), hydrodynamics and sediment transport measurements were analyzed to quantify the inlet dynamics. Our approach was based on the study of hydrosedimentary processes along the adjacent coastline, and inlet responses to...
Tipo: Text Palavras-chave: Embouchure tidale; Morphodynamique; Transport littoral; Delta de jusant; Ria Formosa; Modèles; Tidal inlet; Morphodynamics; Sediment transport; Ebb-tidal delta evolution; Ria Formosa; Models.
Ano: 2001 URL: https://archimer.ifremer.fr/doc/00656/76797/77963.pdf
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Remaniements sédimentaires superficiels sur l'estran occidental de la baie du Mont Saint-Michel ArchiMer
Bonnot-courtois, C; Bassoullet, Philippe; Tessier, B; Cayocca, Florence; Le Hir, Pierre; Baltzer, A.
In order to define and quantify the rhythm and amplitude of the processes of erosion and sedimentation on broad tidal flats, in situ measurements of sediment elevation have been performed in the western part of the Mont-Saint-Michel bay. The amplitude of reworking is generally low (< ± 5 cm), and variable from west to east. The wind influence on tidal currents and surficial reworking emphasizes erosion phases rapidly followed by accretion of similar amplitude on the whole tidal flat. A numerical model for hydrodynamics and sediment transport is applied to Mont Saint Michel Bay, where ecological concerns are related to sediment transfers.
Tipo: Text Palavras-chave: Sediment transport; Numerical model; Erosion sedimentation budget; "In situ" measurements; Tidal sandy mud flat; Transport sédimentaire; Modèle numérique; Bilan érosion sédimentation; Mesures in situ; Estran sablo vaseux.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-6279.pdf
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Devenir de l'atrazine dans le bassin de Marennes-Oléron (France) - Approche par la modélisation hydrodynamique, hydrosédimentaire et biogéochlmique ArchiMer
Vanhoutte Brunier, Alice.
Atrazine is the most widely used herbicide on cultured areas. This pesticide is degraded during its transport in rivers and streams, to the coastal area. Marennes Oleron is the main french oyster farming area, receiving the fresh water from the Charente river and all the drainage coming from the coastal cultivated marshlands. Agriculture is thus claimed to be responsible for shellfish mortality in the aquaculture area. To simulate the changing fate of atrazine in the environment, a modelling strategy has been selected, a) First, using a two-way hydrodynamic model developped by IFREMER, the atrazine dilution trail in the Marennes Oleron area was simulated.Combined with larvae bioassays of Crassostrea gigas (Japanese oyster), the results show atrazine rates...
Tipo: Text Palavras-chave: Produits phytosanitaires; Atrazine; Cycle biogéochimique; Modélisation; Dynamique sédimentaire; Vasières intertidales.; Pesticides; Atrazine; Biogeochemical cycle; Models; Sediment transport; Intertidal muflats..
Ano: 2001 URL: http://archimer.ifremer.fr/doc/00306/41764/40977.pdf
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Modélisation morphodynamique d'une embouchure tidale : Application aux Passes d'entrée du Bassin d'Arcachon ArchiMer
Cayocca, Florence.
The Arcachon tidal inlet exhibits a particularly active morphology due to strong tidal currents and rough wave conditions. During the past 300 years, maximum and minimum extents of the Cap Ferret sand spit have resulted in a difference of 8 km while two channels have alternatively allowed circulation between the lagoon and the ocean. A bidimensional horizontal morphodynarnic model was developed in order to simulate the system evolution under tidal forcing alone or under combined tide and wave action. Modelling at a scale of decades requires the definition of mean annual wave and tide conditions which are representative with respect to sediment transport. Medium term results thus give general trends of evolution. Driven by these average conditions and...
Tipo: Text Palavras-chave: Littoral drift; Sediment transport; Tide; Waves; Arcachon lagoon; Tidal inlet; Modelling; Morphodynamic; Dérive littorale; Transport sédimentaire; Marée; Houle; Bassin d'Arcachon; Modèle; Morphodynamique.
Ano: 1996 URL: http://archimer.ifremer.fr/doc/1996/these-4520.pdf
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Some evidences of northward fine sediment transport in the northern Portuguese continental shelf ArchiMer
Drago, T; Oliveira, A; Magalhaes, F; Cascalho, J; Jouanneau, Jm; Vitorino, Joao.
On the basis of sedimentological and oceanographical data, a transport scheme for fine-grained material is proposed in order to explain the location of a muddy deposit present in the northern Portuguese continental shelf, north-west off the Douro River mouth. This mid-shelf deposit is recent, active and its main source is apparently the Douro River. The sediment supply can be related with the oceanographic conditions in winter regime, characterised by a poleward along shelf current with a bottom westward component, as a consequence of a south-west wind. The resulting fine sediment transport, essentially made in the bottom nepheloid layer is believed to have a north-west direction.
Tipo: Text Palavras-chave: Plateau continental portugais; Sédiment fin; Biotite; Transport de sédiments; Hydrologie hivernale; Portuguese shelf; Fine sediments; Biotite; Sediment transport; Winter regime.
Ano: 1998 URL: http://archimer.ifremer.fr/doc/00326/43681/43193.pdf
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Wave- and current-induced bottom shear stress distribution in the Gulf of Lions ArchiMer
Dufois, Francois; Garreau, Pierre; Le Hir, Pierre; Forget, P.
Simulations of both currents and waves were performed throughout the year 2001 to assess the relative contribution of each to their overall erosive potential on the Gulf of Lions shelf. Statistical analysis of bottom shear stress (BSS) was compared to sediment grain-size distribution on the bottom. The hydrodynamic features of the bottom layer coincide with the distribution of surficial sediments, and three areas with different hydro-sedimentary characteristics were revealed. (i) The sandy inner shelf ( < 30 m) area is a high-energy-wave dominated area but may be subjected to intense current-induced BSS during on-shore winds along the coast and during continental winds mainly in the up-welling cells. (ii) The middle shelf (30-100 m) is a low-energy...
Tipo: Text Palavras-chave: Gulf of Lions; 3D modelling; Bottom shear stress; Sediment transport.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-6305.pdf
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Fortnightly tidal asymmetry inversions and perspectives on sediment dynamics in a macrotidal estuary (Charente, France) ArchiMer
Toublanc, Florence; Brenon, Isabelle; Coulombier, T.; Le Moine, Olivier.
Tidal asymmetry is a phenomenon that characterises estuarine hydrodynamics and has a strong impact on sediment dynamics. Extensive research has been dedicated to studying tidal dynamics in semidiurnal macrotidal estuaries, highlighting several general principles. The ratio of flood to ebb peak velocities and differences in ebb and flood durations are often used to characterise the asymmetry encountered in estuaries. In the Charente estuary (French Atlantic coast), water surface elevation data obtained using an ADCP (Acoustic Doppler Current Profiler) and a tide gauge show that the duration asymmetry undergoes inversions during the spring-neap tidal cycle. A two-dimensional hydrodynamics model is used to investigate the connection between spring-neap...
Tipo: Text Palavras-chave: Estuary; Tidal asymmetry; Duration asymmetry; Ebb/flood dominance; Morphology; External/internal overtides; Sediment transport.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00245/35650/40645.pdf
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High-Resolution Morphobathymetric Analysis and Evolution of Capbreton Submarine Canyon Head (Southeast Bay of Biscay—French Atlantic Coast) over the Last Decade Using Descriptive and Numerical Modeling ArchiMer
Mazieres, Alais; Gillet, Herve; Castelle, Bruno; Mulder, Thierry; Guyot, Corentin; Garlan, Thierry; Mallet, Cyril.
In this study, the Capbreton canyon head, just off the coast, is investigated using high-resolution multibeam bathymetry datasets, sediment samples and numerical modeling. The HR bathymetry analysis reveals a morphological connection between the longshore trough and the head of the canyon. The analysis of recent sediment samples shows a clear correlation between the sediment of the canyon head and that of the nearshore. Hydrodynamic modeling (a coupled wave-flow model) shows that for high-energy waves, the rotational nature of surf-zone circulation reverses and wave-induced currents have the potential to transport large quantities of nearshore sands toward the canyon head. All these arguments support the assumption that the canyon head captures a part of...
Tipo: Text Palavras-chave: Longshore drift; Submarine canyon; Capbreton; Hydrodynamic modeling; Sediment transport.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00180/29118/27524.pdf
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Modelisation morphodynamique de l'embouchure de la seine ArchiMer
Waeles, Benoit.
The mouth of the Seine has been undergoing intense morphological changes for decades, because of containment work to improve access to the ports of Rouen and Le Havre. A significant trend is the progradation of the downstream estuary. Simultaneously, the surface area of the intertidal mudflats tends to decrease. The estuary's sediments are composed of silt and fine sand (respectively transported from the river Seine and the open sea). Their distribution is linked to the hydrodynamic characteristics of the estuary and may display layered vertical structures. To understand the estuary's morphological changes, a morphodynamic ditigal model is developed from a validated (3D) model of silty sediment transport. A model of suspended fine sand transport as well as...
Tipo: Text Palavras-chave: Seine estuary; Modelling; Sediment transport; Hydrodynamic; Morphodynamic; Seine estuaire; Modelisation; Transport sediment; Hydrodynamique; Morphodynamique.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/these-2195.pdf
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Impact of winter storms on sediment erosion in the Rhone River prodelta and fate of sediment in the Gulf of Lions (North Western Mediterranean Sea) ArchiMer
Dufois, Francois; Verney, Romaric; Le Hir, Pierre; Dumas, Franck; Charmasson, Sabine.
In this study a three-dimensional sediment transport model was developed. The model accounts for both current and wave forcing on the sediment and was implemented over the Gulf of Lions. A two-way nesting technique was used to focus on the Rhone River prodelta which is considered as a sink for riverine sediment. In addition, to understand the resuspension of trapped sediment over the Rhone prodelta, an in situ experiment, called SCOPE, was conducted during the winter 2007/2008. The experiment consisted of measuring hydro-sedimentary parameters using a mooring station comprising a current profiler (ADCP) and an altimeter (acoustic transducer) located in the eastern part of the Rhone prodelta. The three-dimensional transport model was validated using these...
Tipo: Text Palavras-chave: Sediment transport; Gulf of Lions; Rhone prodelta; 3D modelling; ADCP; ALTUS.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00165/27584/25743.pdf
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Numerical modelling of heterogeneous sediment transport: new insights for particulate radionuclide transport and deposition ArchiMer
Rivier, Aurélie; Le Hir, Pierre; Bailly Du Bois, Pascal; Laguionie, Philippe; Morillon, Mehdi.
A sediment transport module which solves simultaneously bedload and suspended load is developed, in a context of multiclass sediment transport. Different approaches are used to simulate each transport mode: (i) bedload transport results from divergence of transport capacity and (ii) suspension transport is solved using erosion and settling fluxes associated with advection/diffusion equation. A focus is made on the significance of hiding and exposure processes in case of heterogeneous sediment bed. Their influence is strong on bedload sediment transport, and induces specific trends of sediment sorting in sand dunes. The application to heterogeneous sediment dynamics in the macrotidal area of the Normand Breton Gulf (English Channel), show that hiding and...
Tipo: Text Palavras-chave: Sediment transport; Numerical modelling; Hiding; Exposure; Bedload; Suspension.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00394/50580/51274.pdf
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Numerical modeling of bottom trawling-induced sediment transport and accumulation in La Fonera submarine canyon, northwestern Mediterranean Sea ArchiMer
Payo-payo, Marta; Silva Jacinto, Ricardo; Lastras, G.; Rabineau, Marina; Puig, P.; Martin, J.; Canals, M.; Sultan, Nabil.
Bottom trawling leads to recurrent sediment resuspension events over fishing grounds. Recent studies have shown how bottom trawling can drive seascape reshaping at large spatial scales and enhance sediment transport in submarine canyons, which subsequently impacts deep-sea ecosystems. Present knowledge on the transfer and accumulation of sediment flows triggered by bottom trawling is based on localized and infrequent measurements whilst a more complete picture of the process is needed. The present work focuses on the modeling of sediment transport and accumulation resulting from trawling activities in La Fonera submarine canyon, northwestern Mediterranean Sea, thus contributing to an improved assessment of trawling impacts. Based on mooring data within a...
Tipo: Text Palavras-chave: Bottom trawling; Inverse model; Modeling; Sediment transport; Submarine canyon; Turbidity currents.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00374/48549/48862.pdf
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Synthese des connaissances sur les effets du depot de dragage d''Octeville ArchiMer
Chauvin, P; Freger, G; Guyader, Julie.
Le Havre Harbour dredging wastes are deposited off Octeville and cause the spreading of muds in this area. Currents disperse the sediments on a large zone. Physico-chemical analysis show low micropolluants concentrations. Water quality seems not to be affected by these deposits, but a reduction of species living in the sediments is observed.
Tipo: Text Palavras-chave: Water quality; Sediment transport; Waste disposal sites; Environmental impact; Sediment pollution; Dredge spoil; Ocean dumping.
Ano: 1985 URL: http://archimer.ifremer.fr/doc/1985/acte-1316.pdf
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Evaluation des apports fluviatiles dans l''estuaire de la Seine ArchiMer
Avoine, J.
Economic activities and urbanization along the Seine watershed, are the main factors of increased river discharge with natural deposits. A long term supervision of this river has allowed the assessment of the liquid flow rate, the solid load, and the metallic pollution.
Tipo: Text Palavras-chave: Seasonal variations; Trace metals; Sediment transport; Fluid flow; Brackishwater pollution; Estuarine sedimentation; River discharge.
Ano: 1985 URL: http://archimer.ifremer.fr/doc/1985/acte-1274.pdf
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Optical algorithms at satellite wavelengths for Total Suspended Matter in tropical coastal waters ArchiMer
Ouillon, Sylvain; Douillet, Pascal; Petrenko, Anne; Neveux, Jacques; Dupouy, Cecile; Froidefond, Jean-marie; Andrefouet, Serge; Munoz-caravaca, Alain.
Is it possible to derive accurately Total Suspended Matter concentration or its proxy, turbidity, from remote sensing data in tropical coastal lagoon waters? To investigate this question, hyperspectral remote sensing reflectance, turbidity and chlorophyll pigment concentration were measured in three coral reef lagoons. The three sites enabled us to get data over very diverse environments: oligotrophic and sediment-poor waters in the southwest lagoon of New Caledonia, eutrophic waters in the Cienfuegos Bay (Cuba), and sediment-rich waters in the Laucala Bay (Fiji). In this paper, optical algorithms for turbidity are presented per site based on 113 stations in New Caledonia, 24 stations in Cuba and 56 stations in Fiji. Empirical algorithms are tested at...
Tipo: Text Palavras-chave: Ocean color; Remote sensing; Sediment transport; Suspended matter; Turbidity; New Caledonia; Cuba; Fiji.
Ano: 2008 URL: https://archimer.ifremer.fr/doc/00203/31417/29808.pdf
Registros recuperados: 34
Primeira ... 12 ... Última
 

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