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

Type Article
Date 2019-04
Language English
Author(s) Gourain Arthur4, Planquette Helene1, Cheize Marie4, Lemaitre Nolwenn, Menzel Barraqueta Jan-Lukas2, Shelley Rachel1, Lherminier PascaleORCID3, Sarthou Geraldine1
Affiliation(s) 1 : UMR 6539/LEMAR/IUEM, Technopôle Brest Iroise, Place Nicolas Copernic, 29280 Plouzané, France
2 : GEOMAR, Helmholtz Centre for Ocean Research Kiel, Wischhofstraße 1–3, 24148 Kiel, Germany
3 : Ifremer, LPO, UMR 6523 CNRS/Ifremer/IRD/UBO, Ifremer Centre de Brest, CS 10070, Plouzané, France
Source Biogeosciences (1726-4170) (Copernicus GmbH), 2019-04 , Vol. 16 , N. 7 , P. 1563-1582
DOI 10.5194/bg-16-1563-2019
WOS© Times Cited 6
Note Special issue GEOVIDE, an international GEOTRACES study along the OVIDE section in the North Atlantic and in the Labrador Sea (GA01) Editor(s): G. Henderson, C. Jeandel, M. Lohan, G. Reverdin, and L. Bopp
Abstract

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 as low as 9 pmol L−1 in surface Labrador Sea waters 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. At most stations over the Western, the relative concentrations of total PFe and aluminium (PAl) showed the near-ubiquitous 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 of the PFe / PAl ratio (up to 0.7 mol mol−1) compared to the continental crust ratio (0.21 mol mol−1), Margins provide important quantities of particulate trace elements (up to 10 nmol L−1 of PFe) to the open ocean, and in the case of the Iberian margin, advection of PFe was visible more than 250 km away from the margin. Additionally, several benthic nepheloid layers spreading over 200m above the seafloor were encountered along the transect, especially in the Icelandic, Irminger and Labrador basins, delivering particles with high PFe content, up to 89 nmol L−1 of PFe. Finally, remineralisation processes are also discussed, and showed different patterns among basins and elements.

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How to cite 

Gourain Arthur, Planquette Helene, Cheize Marie, Lemaitre Nolwenn, Menzel Barraqueta Jan-Lukas, Shelley Rachel, Lherminier Pascale, Sarthou Geraldine (2019). Inputs and processes affecting the distribution of particulate iron in the North Atlantic along the GEOVIDE (GEOTRACES GA01) section. Biogeosciences, 16(7), 1563-1582. Publisher's official version : https://doi.org/10.5194/bg-16-1563-2019 , Open Access version : https://archimer.ifremer.fr/doc/00485/59676/