The biogeochemistry of cobalt in the Mediterranean Sea

• Published in: Global Biogeochemical Cycles
• Main Authors: Dulaquais, Gabriel, Planquette, Hélène, L'Helguen, Stéphane, Rijkenberg, Micha, Boye, Marie
• Other Authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Royal Netherlands Institute for Sea Research (NIOZ), ANR-12-PDOC-0025,BITMAP,Biodisponibilité du fer et des métaux traces dans les particules marines(2012)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: DISSOLVED COBALT; NORTH-ATLANTIC; TRACE-METAL COMPOSITION; CATHODIC STRIPPING VOLTAMMETRY; WESTERN ATLANTIC-OCEAN; MARINE DIATOM; CARBON EXPORT; INTERANNUAL VARIABILITY; PHOSPHORUS LIMITATION; ELEMENTAL COMPOSITION; ACL; [SDE]Environmental Sciences; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-02332035; https://hal.archives-ouvertes.fr/hal-02332035/document; https://hal.archives-ouvertes.fr/hal-02332035/file/Dulaquais%20et%20al%20GBC%202017.pdf; https://doi.org/10.1002/2016GB005478

International audience The soluble (sCo < 0.02 μm), dissolved (DCo < 0.2 μm), colloidal (cCo, as DCo minus sCo), and the particulate (pCo > 0.2 μm) fractions of cobalt were investigated along the GEOTRACES-A04 section. Our results show that sCo was the predominant form (90%) of the DCo in the Mediterranean Sea and that cCo and pCo generally followed the same distribution, suggesting a biogeochemical link between these two fractions. In the Mediterranean Sea, DCo displayed an overall scavenged-like profile in the different sub-basins, with high concentrations (up to 350 pM) in surface and quasi-uniformed low concentrations of DCo (~45 pM) in the deep sea. However, the decoupling between the surface and the deep reservoirs suggested that the transfer of Co from dissolved to particulate pools during the sink of particles may not be the only process governing DCo distribution. High-surface Co inputs, stabilization of DCo in a soluble form, and the extremely high regeneration rate of biogenic pCo all lead to the accumulation of DCo in surface. Conversely, low pCo export from the surface waters, low remineralization of biogenic pCo, and slow but efficient removal of DCo by scavenging including colloid aggregation into particles prevented its accumulation in the intermediate and deep sea. Moreover, Mediterranean circulation prevented the exchanges between the DCo-rich surface and the DCo-poor deep layers enhancing the scavenged-like profile of DCo. Finally, tentative DCo budgets were balanced at basin scale and showed the strong imprint of the surface inputs at Gibraltar Strait on the Mediterranean cobalt biogeochemistry.