Inputs and processes affecting the distribution of particulate iron in the North Atlantic along the GEOVIDE (GEOTRACES GA01) section

• Published in: Biogeosciences
• Main Authors: Gourain, Arthur, Planquette, Hélène, Cheize, Marie, Lemaitre, Nolwenn, Menzel Barraqueta, Jan-Lukas, Shelley, Rachel, Lherminier, Pascale, Sarthou, Géraldine
• 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 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)-Centre National de la Recherche Scientifique (CNRS), Helmholtz Centre for Ocean Research Kiel (GEOMAR), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), ANR-12-PDOC-0025,BITMAP,Biodisponibilité du fer et des métaux traces dans les particules marines(2012), ANR-13-BS06-0014,GEOVIDE,GEOVIDE, Une étude internationale GEOTRACES le long de la section OVIDE en Atlantique Nord et en Mer du Labrador(2013), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: OCEANIC DISSOLVED IRON; NEPHELOID LAYER; WATER COLUMN; LABRADOR SEA; CARBON REMINERALIZATION; TEMPORAL VARIABILITY; MATERIAL DISSOLUTION; SUSPENDED PARTICLES; MANGANESE; ALUMINUM; ACL; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Pourquoi Pas; Pourquoi-Pas; Pourquoi-Pas?; Labrador Sea; North Atlantic
• Online Access: https://hal.science/hal-02322470; https://hal.science/hal-02322470/document; https://hal.science/hal-02322470/file/Gourain_etal_Biogeosciences_2019.pdf; https://doi.org/10.5194/bg-16-1563-2019

International audience The aim of the GEOVIDE cruise (May-June 2014, R/V Pourquoi Pas?) was to provide a better understanding of trace metal biogeochemical cycles in the North Atlantic Ocean. As marine 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 relation to the distribution of particulate aluminium (PAl), manganese (PMn), and phosphorus (PP). 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, and adsorptive scavenging processes in key areas of the thermohaline overturning circulation. Total particulate iron concentrations ranged from as low as 9 pmol L-1 in surface waters of the Labrador Sea to 304 nmol L-1 near the Iberian margin, while median PFe concentrations of 1.15 nmol L-1 were measured over the sub-euphotic ocean interior.Within the Iberian Abyssal Plain, the ratio of PFe to PAl was identical to the continental crust molar ratio (0.21 mol mol(-1)), indicating the important influence of crustal particles in the water column. Overall, the lithogenic component explained more than 87% of PFe variance along the section. Within the Irminger and Labrador basins, the formation of biogenic particles led to an increase in the PFe/PAl ratio (up to 0.64 mol mol(-1)) compared to the continental crust ratio. Continental margins induce high concentrations of particulate trace elements within the surrounding water masses (up to 10 nmol L-1 of PFe). For example, horizontal advection of PFe was visible more than 250 km away from the Iberian margin. Additionally, several benthic nepheloid layers were observed more than 200m above the seafloor along the transect, especially in the Icelandic, Irminger, and Labrador basins, suspending particles with high PFe content of up to 89 nmol L-1.