Impact of inorganic particles of sedimentary origin on global dissolved iron and phytoplankton distribution

Type Article
Date 2019-12
Language English
Author(s) Beghoura H.1, Gorgues Thomas1, Aumont Olivier2, Planquette Helene3, Tagliabue A.4, Auger P.‐a.1, 5
Affiliation(s) 1 : Univ. Brest, CNRS, IRD, Ifremer, Laboratoire d’Océanographie Physique et Spatiale (LOPS), IUEM Brest, France
2 : Sorbonne Université, UPMC Université Paris VI, CNRS, IRD, MNHN, UMR7159 LOCEAN‐IPSL Paris ,France
3 : Laboratoire des Sciences de l’Environnement Marin (LEMAR), CNRS, UBO, IRD, Ifremer Plouzané ,France
4 : Department of Earth, Ocean & Ecological Sciences, School of Environmental Sciences University of Liverpool Liverpool, UK
5 : Instituto Milenio de Oceanografía (IMO) and Escuela de Ciencias del Mar Pontificia Universidad Católica de Valparaíso Valparaíso ,Chile
Source Journal Of Geophysical Research-oceans (2169-9275) (American Geophysical Union (AGU)), 2019-12 , Vol. 124 , N. 12 , P. 8626-8646
DOI 10.1029/2019JC015119
WOS© Times Cited 4
Abstract

Iron is known to be the limiting nutrient for the phytoplankton growth over ~40% of the global ocean and to impact the structure of marine ecosystems. Dissolved iron (DFe) is assumed to be the only form available to phytoplankton while particulate iron (PFe) has mostly been considered for its role in the biogenic iron remineralization and induced scavenging. Therefore, most studies focused on the nature of DFe external sources to the ocean (i.e. aeolian dust, riverine fluxes, hydrothermal sources and sediment) and their quantification, which still remain uncertain. Among these external sources, the sedimentary sources have been shown to be underestimated. Moreover, the iron supply from sediments has been documented to be often larger in the particle fraction. Here, we test the impacts of an iron sediment source of inorganic particulate iron (PFeInorg) on global DFe and phytoplankton distribution. We use experimentally acquired knowledge to test a parameterization of a PFeInorg pool in a global biogeochemical model and compare with published indirect estimation. Depending on the parameterization of its dissolution and sinking speed, the PFeInorg can noticeably enrich water masses in DFe during its transport from the sediment to the open ocean, notably in regions not usually accessible to external DFe inputs. Indeed, the fact that DFe is prone to scavenging, reduces the impact of equivalent Fe inputs from sediments in the dissolved form in those regions far from the sediment sources. PFeInorg thereby has the potential to fuel the phytoplankton growth in offshore regions impacting the coastal‐offshore chlorophyll gradient.

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Beghoura H., Gorgues Thomas, Aumont Olivier, Planquette Helene, Tagliabue A., Auger P.‐a. (2019). Impact of inorganic particles of sedimentary origin on global dissolved iron and phytoplankton distribution. Journal Of Geophysical Research-oceans, 124(12), 8626-8646. Publisher's official version : https://doi.org/10.1029/2019JC015119 , Open Access version : https://archimer.ifremer.fr/doc/00591/70270/