Consulta: creatorFacets:"Lemaitre, Nolwenn"
Registros recuperados: 14
Data/hora: 09/06/2024 04:46:46

Differentiating Lithogenic Supplies, Water Mass Transport, and Biological Processes On and Off the Kerguelen Plateau Using Rare Earth Element Concentrations and Neodymium Isotopic Compositions
Provedor de dados: 5
Autores: Grenier, Melanie; Garcia-solsona, Ester; Lemaitre, Nolwenn; Trull, Thomas W.; Bouvier, Vincent; Nonnotte, Philippe; Van Beek, Pieter; Souhaut, Marc; Lacan, Francois; Jeandel, Catherine.
Distributions of dissolved rare earth element (REE) concentrations and neodymium isotopic compositions (expressed as epsilon(Nd)) of seawater over and off the Kerguelen Plateau in the Southern Ocean are presented. The sampling took place during the austral spring bloom in October-November 2011 (KEOPS2 project, GEOTRACES process study) and aimed to further the investigations of the KEOPS1 austral summer study in terms of sources and transport of lithogenic material, and to investigate the impact of local biogeochemical cycles on the REE distributions. The REE signature of the coastal eastern Kerguelen Islands waters was characterized by negative europium anomalies (Eu/Eu*) and negative epsilon(Nd) in filtered samples. By contrast, the unfiltered sample...
Tipo: Text
Palavras-chave: Southern Ocean; Kerguelen Islands; Rare earth elements; Fractionation; Anomalies; Lithogenic; Biologic; GEOTRACES.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00616/72764/72274.pdf

Introduction to the French GEOTRACES North Atlantic Transect (GA01): GEOVIDE cruise
Provedor de dados: 5
Autores: Sarthou, Geraldine; Lherminier, Pascale; Achterberg, Eric P.; Alonso-perez, Fernando; Bucciarelli, Eva; Boutorh, Julia; Bouvier, Vincent; Boyle, Edward A.; Branellec, Pierre; Carracedo, Lidia I.; Casacuberta, Nuria; Castrillejo, Maxi; Cheize, Marie; Pereira, Leonardo Contreira; Cossa, Daniel; Daniault, Nathalie; De Saint-leger, Emmanuel; Dehairs, Frank; Deng, Feifei; De Gesincourt, Floriane Desprez; Devesa, Jeremy; Foliot, Lorna; Fonseca-batista, Debany; Gallinari, Morgane; Garcia-ibanez, Maribel I.; Gourain, Arthur; Grossteffan, Emilie; Hamon, Michel; Heimburger, Lars Eric; Henderson, Gideon M.; Jeandel, Catherine; Kermabon, Catherine; Lacan, Francois; Le Bot, Philippe; Le Goff, Manon; Le Roy, Emilie; Lefebvre, Alison; Leizour, Stephane; Lemaitre, Nolwenn; Masque, Pere; Menage, Olivier; Barraqueta, Jan-lukas Menzel; Mercier, Herle; Perault, Fabien; Perez, Fiz F; Planquette, Helene; Planchon, Frederic; Roukaerts, Arnout; Sanial, Virginie; Sauzede, Raphaelle; Schmechtig, Catherine; Shelley, Rachel U.; Stewart, Gillian; Sutton, Jill; Tang, Yi; Tisnerat-laborde, Nadine; Tonnard, Manon; Treguer, Paul; Van Beek, Pieter; Zurbrick, Cheryl M.; Zunino Rodriguez, Patricia.
The GEOVIDE cruise, a collaborative project within the framework of the international GEOTRACES programme, was conducted along the French-led section in the North Atlantic Ocean (Section GA01), between 15 May and 30 June 2014. In this special issue (https://www.biogeosciences.net/special_ issue900.html), results from GEOVIDE, including physical oceanography and trace element and isotope cyclings, are presented among 18 articles. Here, the scientific context, project objectives, and scientific strategy of GEOVIDE are provided, along with an overview of the main results from the articles published in the special issue.
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00470/58178/60685.pdf

Inputs and processes affecting the distribution of particulate iron in the North Atlantic along the GEOVIDE (GEOTRACES GA01) section
Provedor de dados: 5
Autores: Gourain, Arthur; Planquette, Helene; Cheize, Marie; Lemaitre, Nolwenn; Menzel Barraqueta, Jan-lukas; Shelley, Rachel; Lherminier, Pascale; Sarthou, Geraldine.
The GEOVIDE cruise (May–June 2014, R/V Pourquoi Pas?) aimed to provide a better understanding on trace metal biogeochemical cycles in the North Atlantic. As particles play a key role in the global biogeochemical cycle of trace elements in the ocean, we discuss the distribution of particulate iron (PFe), in light of particulate aluminium (PAl), manganese (PMn) and phosphorus (PP) distributions. Overall, 32 full vertical profiles were collected for trace metal analyses, representing more than 500 samples. This resolution provides a solid basis for assessing concentration distributions, elemental ratios, size-fractionation, or adsorptive scavenging processes in key areas of the thermohaline circulation. Total particulate iron (PFe) concentrations ranged from...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00485/59676/62747.pdf

The export flux of particulate organic carbon derived from 210Po∕210Pb disequilibria along the North Atlantic GEOTRACES GA01 transect: GEOVIDE cruise
Provedor de dados: 5
Autores: Tang, Yi; Lemaitre, Nolwenn; Castrillejo, Maxi; Roca-martí, Montserrat; Masqué, Pere; Stewart, Gillian.
The disequilibrium between 210Po activity and 210Pb activity in seawater samples was determined along the GEOTRACES GA01 transect in the North Atlantic during the GEOVIDE cruise (May–June 2014). A steady-state model was used to quantify vertical export of particulate 210Po. Vertical advection was incorporated into one version of the model using time-averaged vertical velocity, which had substantial variance. This resulted in large uncertainties for the 210Po export flux in this model, suggesting that those calculations of 210Po export fluxes should be used with great care. Despite the large uncertainties, there is no question that the deficits of 210Po in the Iberian Basin and at the Greenland Shelf have been strongly affected by vertical advection. Using...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00485/59668/62731.pdf

Particulate Rare Earth Element behavior in the North Atlantic (GEOVIDE cruise)
Provedor de dados: 5
Autores: Lagarde, Marion; Lemaitre, Nolwenn; Planquette, Helene; Grenier, Mélanie; Belhadj, Moustafa; Lherminier, Pascale; Jeandel, Catherine.
Particulate concentrations of the fourteen Rare Earth Elements (PREE), yttrium and 232-thorium have been measured in two hundred samples collected in the epipelagic (ca. 0–200 m) and the mesopelagic (ca. 200–1000 m) zones of the North Atlantic, during the GEOVIDE cruise (May/June 2014, R/V Pourquoi Pas ?, GEOTRACES GA01). Particulate cerium (PCe) concentrations vary from 0.2 pmol L−1 to 16 pmol L−1, particulate neodymium (PNd) ones from 0.09 pmol L−1 to 6.1 pmol L−1 and particulate ytterbium (PYb) ones from 0.01 pmol L−1 to 0.5 pmol L−1. PREE concentrations are higher close to the Iberian margin and on the Greenland shelf, where PREE concentrations normalized to Post Archean Australian Shale (PAAS) display a positive Ce anomaly between 0.3 and 3, and a...
Tipo: Text
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00601/71323/69750.pdf

Microbial utilization of rare earth elements at cold seeps related to aerobic methane oxidation
Provedor de dados: 5
Autores: Bayon, Germain; Lemaitre, Nolwenn; Barrat, Jean-alix; Wang, Xudong; Feng, Dong; Duperron, Sebastien.
A major breakthrough in the field of rare earth element (REE) geochemistry has been the recent discovery of their utility to microbial life, as essential metalloenzymes catalyzing the oxidation of methanol to formaldehyde. Lanthanide-dependent bacteria are thought to be ubiquitous in marine and terrestrial environments, but direct field evidence of preferential microbial utilization of REE in natural systems is still lacking. In this study, we report on the REE and trace element composition of the tube of a siboglinid worm collected at a methane seep in the Gulf of Guinea; a tube-dwelling annelid that thrives in deep-sea chemosynthetic ecosystems. High-resolution trace element profiles along the chitin tube indicate marked enrichments of lanthanum (La) and...
Tipo: Text
Palavras-chave: Tubeworms; Siboglinidae; Lanthanide-dependent bacteria; Metalloenzymes; Methylotrophy; Regab; Authigenic carbonates; Archaean.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00643/75496/76352.pdf

High variability of particulate organic carbon export along the North Atlantic GEOTRACES section GA01 as deduced from 234Th fluxes
Provedor de dados: 5
Autores: Lemaitre, Nolwenn; Planchon, Frederic; Planquette, Helene; Dehairs, Frank; Fonseca-batista, Debany; Roukaerts, Arnout; Deman, Florian; Tang, Yi; Mariez, Clarisse; Sarthou, Geraldine.
In this study we report particulate organic carbon (POC) export fluxes for different biogeochemical basins in the North Atlantic as part of the GEOTRACES GA01 expedition (GEOVIDE, May–June 2014). Surface POC export fluxes were deduced by combining export fluxes of total Thorium-234 (234Th) with the ratio of POC to 234Th of sinking particles at the depth of export. Particles were collected in two size classes ( &gt; 53 and 1–53µm) using in situ pumps and the large size fraction was considered representative of sinking material. Surface POC export fluxes revealed latitudinal variations between provinces, ranging from 1.4mmolm−2d−1 in the Irminger basin, where the bloom was close to its maximum, to 12mmolm−2d−1 near the Iberian Margin, where the bloom had...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00465/57664/59860.pdf

Evidence of high N2 fixation rates in productive waters of the temperate Northeast Atlantic
Provedor de dados: 5
Autores: Fonseca-batista, Debany; Li, Xuefeng; Riou, Virginie; Michotey, Valérie; Deman, Forian; Fripiat, François; Guasco, Sophie; Brion, Natacha; Lemaitre, Nolwenn; Tonnard, Manon; Gallinari, Morgane; Planquette, Hélène; Planchon, Frédéric; Sarthou, Géraldine; Elskens, Marc; Laroche, Julie; Chou, Lei; Dehairs, Frank.
Diazotrophic activity and primary production (PP) were investigated along two transects (Belgica BG2014/14 and GEOVIDE cruises) off the western Iberian Margin and the Bay of Biscay (38.8–46.5°N; 8.0–19.7°W) in May 2014 close to the end of the spring bloom. We report substantial N2 fixation activities, reaching up to 65nmolNL−1d−1 and 1533µmolNm−2d−1 close to the Iberian Margin between 38.8°N and 40.7°N. Similar figures in the basin have only been reported in the temperate and tropical western North Atlantic waters with coastal, shelf or mesohaline characteristics, as opposed to the mostly open ocean conditions studied here. In agreement with previous studies, the qualitative assessment of nifH gene diversity (encoding the nitrogenase enzyme that fixes N2)...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00461/57266/59317.pdf

Pervasive sources of isotopically light zinc in the North Atlantic Ocean
Provedor de dados: 5
Autores: Lemaitre, Nolwenn; De Souza, Gregory F.; Archer, Corey; Wang, Ruo-mei; Planquette, Helene; Sarthou, Geraldine; Vance, Derek.
In this study, we report seawater dissolved zinc (Zn) concentration and isotope composition (Zn) from the GEOTRACES GA01 (GEOVIDE) section in the North Atlantic. Across the transect, three subsets of samples stand out due to their isotopically light signature: those close to the Reykjanes Ridge, those close to the sediments, and those, pervasively, in the upper ocean. Similar to observations at other locations, the hydrothermal vent of the Reykjanes Ridge is responsible for the isotopically light Zn composition of the surrounding waters, with an estimated source Zn of -0.42 ‰. This isotopically light Zn is then transported over a distance greater than 1000 km from the vent. Sedimentary inputs are also evident all across the trans-Atlantic section,...
Tipo: Text
Palavras-chave: Zinc isotopes; North Atlantic; Zinc sources; GEOTRACES; GEOVIDE.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00618/73035/72166.pdf

Distributions of total and size-fractionated particulate 210Po and 210Pb activities along the North Atlantic GEOTRACES GA01 transect: GEOVIDE cruise
Provedor de dados: 5
Autores: Tang, Yi; Castrillejo, Maxi; Roca-martí, Montserrat; Masqué, Pere; Lemaitre, Nolwenn; Stewart, Gillian.
Vertical distributions of total and particulate polonium-210 (210Po) and lead-210 (210Pb) activities in the water column were measured at 11 stations in the North Atlantic during the GEOTRACES GA01 transect: GEOVIDE cruise in May–June 2014. Total 210Po activity was on average 24 % lower than 210Pb activity in the upper 100 m, and it was closer to unity in the mesopelagic (100–1000 m). The partitioning coefficients (Kd) along the transect suggest the preferential association of 210Po relative to 210Pb onto particles. The prominent role of small particles in sorption was confirmed by the observation that over 80 % of the particulate radionuclide activity was on small particles. To account for the observed surface water 210Po ∕ 210Pb disequilibria,...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00485/59671/62736.pdf

Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic
Provedor de dados: 5
Autores: Lemaitre, Nolwenn; Planquette, Helene; Planchon, Frederic; Sarthou, Geraldine; Jacquet, Stephanie; Garcia-ibanez, Maria Isabel; Gourain, Arthur; Cheize, Marie; Monin, Laurence; Andre, Luc; Laha, Priya; Terryn, Herman; Dehairs, Frank.
The remineralisation of sinking particles by prokaryotic heterotrophic activities is important for controlling oceanic carbon sequestration. Here, we report mesopelagic particulate organic carbon (POC) remineralisation fluxes in the North Atlantic along the GEOTRACES-GA01 section (GEOVIDE cruise; May–June 2014) using the particulate biogenic barium (excess barium; Baxs) proxy. Important mesopelagic (100–1000 m) Baxs differences were observed along the transect depending on the intensity of past blooms, the phytoplankton community structure and the physical forcing, including downwelling. The subpolar province was characterized by the highest mesopelagic Baxs content (up to 727 pmol L−1), which was attributed to an intense bloom averaging 6 mg Chl-a m−3...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00412/52308/53075.pdf

Trace element behaviour at cold seeps and the potential export of dissolved iron to the ocean
Provedor de dados: 5
Autores: Lemaitre, Nolwenn; Bayon, Germain; Ondreas, Helene; Caprais, Jean-claude; Freslon, Nicolas; Bollinger, Claire; Rouget, Marie-laure; De Prunele, Alexis; Ruffine, Livio; Olu-le Roy, Karine; Sarthou, Geraldine.
Seawater samples were collected by submersible above methane seeps in the Gulf of Guinea (Regab and Baboon pockmarks) in order to investigate the behaviour of iron (Fe), manganese (Mn) and rare earth elements (REE) during fluid seepage. Our aim was to determine whether cold seeps may represent potential sources of dissolved chemical species to the ocean. Dissolved (&lt;0.45 μm filtered samples) and total dissolvable (unfiltered samples) concentrations were determined over ∼50 m long vertical transects above the seafloor and at various discrete locations within the pockmarks. We show that substantial amounts of Fe and Mn are released into seawater during seepage of methane-rich fluids. Mn is exported almost quantitatively in the dissolved form (more than...
Tipo: Text
Palavras-chave: Iron; Rare earth elements; Cold seeps; Seawater; Organic ligands; Iron-sulfide nanoparticles.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00211/32190/30704.pdf

A microbiological and biogeochemical investigation of the cold seep tubeworm Escarpia southwardae (Annelida: Siboglinidae): Symbiosis and trace element composition of the tube
Provedor de dados: 5
Autores: Duperron, Sebastien; Gaudron, Sylvie M.; Lemaitre, Nolwenn; Bayon, Germain.
Tubeworms within the annelid family Siboglinidae rely on sulfur-oxidizing autotrophic bacterial symbionts for their nutrition, and are among the dominant metazoans occurring at deep-sea hydrocarbon seeps. Contrary to their relatives from hydrothermal vents, sulfide uptake for symbionts occurs within the anoxic subsurface sediment, in the posterior ‘root’ region of the animal. This study reports on an integrated microbiological and geochemical investigation of the cold seep tubeworm Escarpia southwardae collected at the Regab pockmark (Gulf of Guinea). Our aim was to further constrain the links between the animal and its symbiotic bacteria, and their environment. We show that E. southwardae harbors abundant sulfur-oxidizing bacterial symbionts in its...
Tipo: Text
Palavras-chave: Sulfur-oxidizing bacteria; RTCA; Trace elements; RubisCO; Symbiosis.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00191/30251/28683.pdf

Particulate Trace Element Export in the North Atlantic (GEOTRACES GA01 Transect, GEOVIDE Cruise)
Provedor de dados: 5
Autores: Lemaitre, Nolwenn; Planquette, Helene; Dehairs, Frank; Planchon, Frederic; Sarthou, Geraldine; Gallinari, Morgane; Roig, Stéphane; Jeandel, Catherine; Castrillejo, Maxi.
Vertical export of particulate trace elements (pTEs) is a critically underconstrained aspect of their biogeochemistry. Here, we combine elemental analyses on large (&gt;53 μm) particles and 234Th measurements to determine downward export fluxes from the upper layers (40–110 m) of pTEs (Al, Cd, Co, Cu, Fe, Mn, Ni, P, Ti, V, Zn) and mineral phases (lithogenic, Fe- and Mn-oxides, calcium carbonate, and opal) in the North Atlantic along the GEOVIDE transect (Portugal–Greenland–Canada; GEOTRACES GA01 cruise). The role of lithogenic particles in controlling TE fluxes is obvious at proximity of the Iberian margin where the highest pTE export fluxes were estimated (up to 3912 μg/m2/d for pFe). However, high lithogenic and pTE fluxes are also observed up to 1700 km...
Tipo: Text
Palavras-chave: Particulate trace elements; Export fluxes; Multiple carrier phases; Residence times; GEOTRACES.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00656/76810/78174.pdf