Contribution of resuspended sedimentary particles to dissolved iron and manganese in the ocean: An experimental study

• Published in: Chemical Geology
• Main Authors: Cheize, Marie, Planquette, Hélène, Fitzsimmons, N., Pelleter, E., Sherrell, M., Lambert, Christophe, Bucciarelli, Eva, Sarthou, Géraldine, Le Goff, M., Liorzou, C., Chéron, S., Viollier, E., Gayet, N.
• 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), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Rutgers University Newark, Rutgers University System (Rutgers), Department of Oceanography College Station, Texas A&M University College Station, Laboratoire Géosciences Océan (LGO), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire Environnement Profond (LEP), 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 2019
• Subjects: Kerguelen; ACL; Southern Ocean; Biogenic silica; Manganese; Suspended particle dissolution; Sediment; Iron; envir; geo
• Online Access: https://doi.org/10.1016/j.chemgeo.2018.10.003; https://hal.univ-brest.fr/hal-01901666/file/Cheize_etal_CG_2019.pdf; https://hal.univ-brest.fr/hal-01901666

International audience A number of trace metals play essential roles in marine ecosystem structure and biological productivity. Until recently, it has been argued that phytoplankton access primarily dissolved iron, while particulate iron was considered a refractory material with little use biologically and limited interaction with the dissolved pool. In order to assess the transfer mechanisms between sediment-sourced particulate trace metals and the dissolved pool, we conducted a 14-month incubation that reacted resuspended sediments with natural seawater, both originating from the Kerguelen area (KEOPS cruises; Southern Ocean), in the dark, and at concentrations replicating natural conditions. Three types of sediments were investigated (named BioSi, BioSi+ Ca, and Basalt), mostly composed of (i) biogenic silica (bSiO(2)), (ii) bSiO(2) and calcite, and (iii) basaltic fragments, respectively. The release of dissolved silicon (dSi), iron (dFe) and manganese (dMn) was monitored regularly throughout the incubation, as well as living bacteria density and Fe organic ligands. Depending on the origin and composition of the sediment, unique dFe and dMn fluxes were observed, including a strong decoupling between dFe and dMn. The basaltic sediment released up to 1.09 +/- 0.04 nmol L-1 of dFe and 0.28 +/- 0.09 nmol L-1 of dMn, while the biogenic sediments released a higher 3.91 +/- 0.04 nmol L-1 and 8.03 +/- 0.42 nmol L-1 of dFe and dMn, respectively. Several factors influencing the release and removal of dFe and dMn were discernable at the temporal sampling resolution of the incubation, including the structural composition of the sediment, bacterial abundance, and the formation of manganese oxides. The regular sampling over short timescales and the extended sampling over one year proved to be critical to constrain the processes and exchanges that govern the contribution of the particulate to the dissolved pools. Overall, this incubation provides a strong basis for reassessing the role of resuspended sedimentary particles ...