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| Donnadieu, Y; Lecroart, P; Anschutz, P; Bertrand, P. |
| We have constructed a nonsteady state numerical model of organic carbon, aluminum, and uranium burial to examine the dynamic response of sediments to variations on thousand years scale. The three components are defined by distinct behaviors in the sedimentary system. The aluminum is a conservative component, the organic carbon is a nonconservative component degraded in superficial sediment, and the uranium is a component affected by redox conditions. By introducing a simultaneous variation of incoming fluxes of C-org and Al, geochemical profiles of Al, Corg, and U clearly show separate distributions after burial. Each component record the synchronous variation of the incoming fluxes, but the position in the sedimentary pile of the recording differs from a... |
| Tipo: Text |
Palavras-chave: Time lag; Sedimentary system; High-resolution record; Modeling; Bioturbation. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33390/31872.pdf |
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| Bayon, Germain; German, Cr; Nesbitt, Rw; Bertrand, P; Schneider, Rr. |
| [1] Analysis of radiogenic isotopes in marine sediments can provide useful information on the provenance and transport of detrital material, directly relevant to paleoceanographic investigations. Here we show that the detrital Nd isotopic composition of recent SE Atlantic marine sediments matches the complex modern-day hydrography. In these same cores, glacial-interglacial isotopic variations are consistent with previous investigations (using different paleoceanographic proxies), which have shown that the relative influence of North Atlantic Deep Water (NADW) into the South Atlantic was reduced during glacial periods. In a novel departure, however, we also calculate the mass accumulation rates of terrigenous material delivered by each of Circumpolar Deep... |
| Tipo: Text |
Palavras-chave: Neodymium isotopes; Detrital fractions; South Atlantic; Deep water circulation; IMAGES; Marine geology and geophysics : marine sediments processes and transport; Oceanography : general : paleoceanography. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00000/10190/9912.pdf |
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| Pichevin, L; Martinez, P; Bertrand, P; Schneider, R; Giraudeau, J; Emeis, K. |
| In the light of new surface sediment delta(15)N data collected over the Namibian shelf and slope, we examined glacial-interglacial variations of N inventory in the area of Luderitz (25 degrees 6S) by deciphering delta(15)N signals of three cores distributed from the upper to the lower continental slope. The lower slope cores display low delta(15)N during cold periods and high delta(15)N during climatic optima, akin to many other records from the world ocean, whereas the upper slope core displays a high-frequency low-amplitude delta(15)N signal without obvious glacial-interglacial variability. This dissimilarity results from the segregation of the upwelling structure in two cells, decoupling nutrient dynamics of the shelf from those beyond the shelf-edge.... |
| Tipo: Text |
Palavras-chave: Nitrogen cycling; Benguela; Climatic cycles. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00232/34366/32796.pdf |
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| Compere, Chantal; Bellon Fontaine, M.-n.; Bertrand, P; Costa, D; Marcus, P; Poleunis, C; Pradier, C.m.; Rondot, B; Walls, M.g.. |
| Adhesion of micro-organisms to surfaces in marine environments leads to biofouling. The deleterious effects of biofilm growth in the marine environment are numerous and include : energy losses due to increased fluid frictional resistance or to increased heat transfer resistance, risk of corrosion induced by micro-organisms, loss of optical properties, quality control and safety problems. Antifouling agents are generally used to protect surfaces from being affected by such a biofilm. These agents are toxic and can be persistent, causing harmful environmental and ecological effects. Moreover, the use of biocides and regular cleaning considerably increase the maintenance costs of marine industries. An improved knowledge of the biofilm adhesion mechanisms is... |
| Tipo: Text |
Palavras-chave: Biofilm; Surface characterisation; Carbohydrates; Protein; Seawater; Conditioning layer. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/publication-1701.pdf |
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| Bertrand, P; Pedersen, Tf; Schneider, R; Shimmield, G; Lallier-verges, E; Disnar, Jr; Massias, D; Villanueva, J; Tribovillard, N; Huc, Ay; Giraud, X; Pierre, C; Venec-peyre, Mt. |
| Sediments on the Namibian Margin in the SE Atlantic between water depths of similar to1000 and similar to3600 m are highly enriched in hydrocarbon-prone organic matter. Such sedimentation has occurred for more than 2 million years and is geographically distributed over hundreds of kilometers along the margin, so that the sediments of this region contain a huge concentrated stock of organic carbon. It is shown here that most of the variability in organic content is due to relative dilution by buried carbonates. This reflects both export productivity and diagenetic dissolution, not differences in either water column or bottom water anoxia and related enhanced preservation of organic matter. These observations offer a new mechanism for the formation of... |
| Tipo: Text |
Palavras-chave: Petroleum source rocks; Coastal upwelling; Deep-sea sediments; Quaternary climate; Southwestern African Margin. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00224/33553/31977.pdf |
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| Bellon-fontaine, M.-n.; Bertrand, P; Compere, Chantal; Costa, D; Guezennec, Jean; Marcus, P; Poleunis, C.; Pradier, C.-m.; Rondot, B; Walls, M.g.. |
| Numerous works are reported in literature concerning the biofilm growth on surfaces in seawater but the understanding of the adhesion mechanisms in the first steps of immersion is still subject to investigations. A knowledge of the chemical composition and of the kinetics of conditioning layer formation is a central requirement for a sound scientific understanding of biofilm growth. Due to its complexity and to the interdisciplinary nature of the subject, this research asks for the collaboration between the fields of material science, surface analyses, chemistry, marine microbiology and biochemistry. The first steps of biofilm formation on 316L stainless steels immersed in natural sea water have been studied, using a broad range of surface characterisation... |
| Tipo: Text |
Palavras-chave: Sea water; Substrates; Biofilm. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/1998/acte-1699.pdf |
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