Manioc : Portail | resultats 1 - 20 pour la recherche: Birot, Dominique

Histoire générale des Antilles T.4
Auteur(s) : Dessalles, Adrien (1809-1870)
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Voyages aux Isles de l'Amérique (Antilles) : 1693-1705 : trente-deux illustrations d'après des documents de l'époque.Tome 1
Auteur(s) : Labat, Jean-Baptiste (1663-1738)
Auteurs secondaires : T'Serstevens, Albert (1886-1974)
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Toussaint Louverture, général en chef de l'armée de Saint-Domingue, surnommé le premier des Noirs ouvrage écrit d'après des documents inédits et les papiers historiques et secrets de la famille Louverture, orné du portrait authentique du célèbre général et du fac-similé de sa signature
Auteur(s) : Gragnon-Lacoste, Thomas-Prosper (1820-1895)
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Le pays des nègres : voyage à Haiti, ancienne partie française de Saint-Domingue : ouvrage orné d'une carte et de 24 gravures
Auteur(s) : La Selve, Edgar (1849-1892)
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Annales du Conseil souverain de la Martinique, ou tableau historique du gouvernement de cette colonie, depuis son premier établissement jusqu'à nos jours. Auquel on a joint l'analyse raisonnée des loix qu'y ont été publiées, avec des réflexions sur l'utilité ou l'insuffisance de chacune de ces loix en particulier, tome I
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Histoire militaire de la révolution de Saint-Domingue
Auteur(s) : Poyen-Bellisle, Henry de (1839-....)
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Evidence for intense REE scavenging at cold seeps from the Niger Delta margin
Auteur(s) : Bayon, Germain Birot, Dominique Ruffine, Livio Caprais, Jean-claude Ponzevera, Emmanuel Bollinger, C. Donval, Jean-pierre Charlou, Jean-luc

Éditeur(s) : Elsevier Science Bv
Résumé : For many trace elements, continental margins are the location of intense exchange processes between sediment and seawater, which control their distribution in the water column, but have yet to be fully understood. In this study, we have investigated the impact of fluid seepage at cold seeps on the marine cycle of neodymium. We determined dissolved and total dissolvable (TD) concentrations for REE and well-established tracers of fluid seepage (CH4, TDFe, TDMn), and Nd isotopic compositions in seawater samples collected above cold seeps and a reference site (i.e. away from any fluid venting area) from the Niger Delta margin. We also analyzed cold seep authigenic phases and various core-top sediment fractions (pore water, detrital component, easily leachable phases, uncleaned foraminifera) recovered near the hydrocast stations. Methane, TDFe and TDMn concentrations clearly indicate active fluid venting at the studied seeps, with plumes rising up to about 100 m above the seafloor. Depth profiles show pronounced REE enrichments in the non-filtered samples (TD concentrations) within plumes, whereas filtered samples (dissolved concentrations) exhibit slight REE depletion in plumes relative to the overlying water column and display typical seawater REE patterns. These results suggest that the net flux of REE emitted into seawater at cold seeps is controlled by the presence of particulate phases, most probably Fe-Mn oxyhydroxides associated to resuspended sediments. At the reference site, however, our data reveal significant enrichment for dissolved REE in bottom waters, that clearly relates to diffusive benthic fluxes from surface sediments. Neodymium isotopic ratios measured in the water column range from epsilon(Nd) similar to-15.7 to -10.4. Evidence that the epsilon(Nd) values for Antarctic Intermediate waters (AAIW) differed from those reported for the same water mass at open ocean settings shows that sediment/water interactions take place in the Gulf of Guinea. At each site, however, the bottom water epsilon(Nd) signature generally differs from that for cold seep minerals, easily leachable sediment phases, and detrital fractions from local sediments, ruling out the possibility that seepage of methane-rich fluids and sediment dissolution act as a substantial source of dissolved Nd to seawater in the Gulf of Guinea. Taken together, our data hence suggest that co-precipitation of Fe-Mn oxyhydroxide phases in sub-surface sediments leads to quantitative scavenging of dissolved REE at cold seeps, preventing their emission into bottom waters. Most probably, it is likely that diffusion from suboxic surface sediments dominates the exchange processes affecting the marine Nd cycle at the Niger Delta margin. (C) 2011 Elsevier B.V. All rights reserved.
Earth And Planetary Science Letters (0012-821X) (Elsevier Science Bv), 2011-12 , Vol. 312 , N. 3-4 , P. 443-452

Droits : 2011 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00066/17754/15571.pdf
DOI:10.1016/j.epsl.2011.10.008
http://archimer.ifremer.fr/doc/00066/17754/

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