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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 |
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Bejannin, Simon; Tamborski, Joseph James; Van Beek, Pieter; Souhaut, Marc; Stieglitz, Thomas; Radakovitch, Olivier; Claude, Christelle; Conan, Pascal; Pujo-pay, Mireille; Crispi, Olivier; Le Roy, Emilie; Estournel, Claude. |
Determination of submarine groundwater discharge (SGD) from karstic coastal aquifers is important to constrain hydrological and biogeochemical cycles. However, SGD quantification using commonly employed geochemical methods can be difficult to constrain under the presence of large riverine inputs, and is further complicated by the determination of the karstic groundwater endmember. Here, we investigated a coastal region where groundwater discharges from a karstic aquifer system using airborne thermal infrared mapping and geochemical sampling conducted along offshore transects. We report radium data (223Ra, 224Ra, 228Ra) that we used to derive fluxes (water, nutrients) associated with terrestrial groundwater discharge and/or seawater circulation through the... |
Tipo: Text |
Palavras-chave: Submarine groundwater discharge; Mediterranean sea; Radium isotopes; Thermal infrared remote sensing; Nutrient fluxes; GEOTRACES. |
Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00610/72171/70945.pdf |
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Rousseau, Tristan C. C.; Sonke, Jeroen E.; Chmeleff, Jerome; Van Beek, Pieter; Souhaut, Marc; Boaventura, Geraldo; Seyler, Patrick; Jeandel, Catherine. |
Rare earth element (REE) concentrations and neodymium isotopic composition (epsilon Nd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (< 0.45 mu m), colloidal and particulate REE and eNd in the Amazon estuary. A sharp drop in dissolved REE in the low-salinity zone is driven by coagulation of colloidal matter. At mid-salinities, total dissolved REE levels slightly increase, while epsilon Nd values are shifted from the dissolved Nd river endmember (- 8.9) to values typical of... |
Tipo: Text |
Palavras-chave: Earth sciences; Biogeochemistry; Oceanography. |
Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00298/40952/40046.pdf |
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Le Roy, Emilie; Sanial, Virginie; Charette, Matthew A.; Van Beek, Pieter; Lacan, François; Jacquet, Stéphanie H. M.; Henderson, Paul B.; Souhaut, Marc; García-ibáñez, Maribel I.; Jeandel, Catherine; Pérez, Fiz; Sarthou, Géraldine. |
We report detailed sections of radium-226 (226Ra, T1/2 = 1602 y) activities and barium (Ba) concentrations determined in the North Atlantic (Portugal-Greenland-Canada) in the framework of the international GEOTRACES program (GA01 section – GEOVIDE project, May–July 2014). Dissolved 226Ra and Ba are strongly correlated along the GA01 section, a pattern that reflects their similar chemical behavior. Since 226Ra and Ba have been widely used as tracers of water masses and ocean mixing, we investigated more thoroughly their behavior in this crucial region for thermohaline circulation taking advantage of the contrasting biogeochemical patterns existing along the GA01 section. We used an Optimum Multiparameter (OMP) analysis to distinguish the relative... |
Tipo: Text |
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Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00412/52305/53073.pdf |
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Le Roy, Emilie; Sanial, Virginie; Charette, Matthew A.; Van Beek, Pieter; Lacan, Francois; Jacquet, Stephanie H. M.; Henderson, Paul B.; Souhaut, Marc; Garcia-ibanez, Maribel I.; Jeandel, Catherine; Perez, Fiz F; Sarthou, Geraldine. |
We report detailed sections of radium-226 (Ra-226, T-1/2 = 1602 years) activities and barium (Ba) concentrations determined in the North Atlantic (Portugal-Greenland-Canada) in the framework of the international GEO-TRACES program (GA01 section - GEOVIDE project, May-July 2014). Dissolved Ra-226 and Ba are strongly correlated along the section, a pattern that may reflect their similar chemical behavior. Because Ra-226 and Ba have been widely used as tracers of water masses and ocean mixing, we investigated their behavior more thoroughly in this crucial region for thermohaline circulation, taking advantage of the contrasting biogeochemical patterns existing along the GA01 section. We used an optimum multiparameter (OMP) analysis to distinguish the relative... |
Tipo: Text |
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Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00616/72790/72109.pdf |
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Ganachaud, Alexandre; Cravatte, Sophie; Sprintall, Janet; Germineaud, Cyril; Alberty, Marion; Jeandel, Catherine; Eldin, Gerard; Metzl, Nicolas; Bonnet, Sophie; Benavides, Mar; Heimburger, Lars-eric; Lefevre, Jerome; Michael, Susanna; Resing, Joseph; Queroue, Fabien; Sarthou, Geraldine; Rodier, Martine; Berthelot, Hugo; Baurand, Francois; Grelet, Jacques; Hasegawa, Takuya; Kessler, William; Kilepak, Moyep; Lacan, Francois; Privat, Emilien; Send, Uwe; Van Beek, Pieter; Souhaut, Marc; Sonke, Jeroen E.. |
The semi-enclosed Solomon Sea in the southwestern tropical Pacific is on the pathway of a major oceanic circuit connecting the subtropics to the equator via energetic western boundary currents. Waters transiting through this area replenish the Pacific Warm Pool and ultimately feed the equatorial current system, in particular the equatorial undercurrent. In addition to dynamical transformations, water masses undergo nutrient and micronutrient enrichment when coming in contact with the coasts, impacting the productivity of the downstream equatorial region. Broadscale observing systems are not well suited for describing the fine-scale currents and water masses properties in the Solomon Sea, leaving it relatively unexplored. Two multidisciplinary oceanographic... |
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Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00390/50185/50808.pdf |
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