Dissolved iron patterns impacted by shallow hydrothermal sources along a transect through the Tonga‐Kermadec arc

Type Article
Date 2022-07
Language English
Author(s) Tilliette C.ORCID1, Taillandier V.1, Bouruet‐aubertot P.ORCID2, Grima Nicolas3, Maes ChristopheORCID7, Montanes M.1, Sarthou GeraldineORCID4, Vorrath M‐e.5, Arnone V.6, Bressac M.ORCID1, González‐santana D.4, Gazeau F.1, Guieu C.1
Affiliation(s) 1 : Sorbonne Université CNRS Laboratoire d’Océanographie de Villefranche LOV 06230 Villefranche‐sur‐Mer, France
2 : Sorbonne Université CNRS IRD Laboratoire d'Océanographie et de Climatologie par Expérimentation et Approche Numérique (LOCEAN) Paris ,France
3 : Univ Brest CNRS IRD Ifremer Laboratoire d’Océanographie Physique et Spatiale (LOPS UMR 6523) IUEM Brest ,France
4 : Univ Brest CNRS IRD Ifremer LEMAR F‐29280 Plouzane , France
5 : Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research 27568 Bremerhaven, Germany
6 : Instituto de Oceanografía y Cambio Global IOCAG Universidad de Las Palmas de Gran Canaria ULPGC 35017 Las Palmas de Gran Canaria ,Spain
7 : Univ Brest CNRS IRD Ifremer LEMAR F‐29280 Plouzane , France
Source Global Biogeochemical Cycles (0886-6236) (American Geophysical Union (AGU)), 2022-07 , Vol. 36 , N. 7 , P. e2022GB007363 (27p.)
DOI 10.1029/2022GB007363
WOS© Times Cited 7
Keyword(s) dissolved iron, eOMP, hydrothermal sources, western tropical south pacific, biogeochemical processes, iron cycle

In the Western Tropical South Pacific, a hotspot of dinitrogen-fixing organisms has been identified. The survival of these species depends on the availability of dissolved iron (DFe); however, the source of this DFe is still unclear. DFe was measured along a transect from 175°E to 166°W near 19-21°S. The distribution of DFe showed high spatial variability: low concentrations (∼0.2 nmol kg-1) in the South Pacific gyre and high concentrations (up to 50 nmol kg-1) west of the Tonga arc, indicating that this arc is a clear boundary between iron-poor and iron-rich waters. An optimal multiparameter analysis was used to distinguish the relative importance of physical transport relative to non-conservative processes on the observed distribution. This analysis demonstrated that the shallow hydrothermal sources present along the Tonga-Kermadec arc are responsible for the high concentrations observed in the photic layer. Nevertheless, in contrast to what has been observed for deep hydrothermal plumes, our results highlighted the rapid decrease in DFe concentrations near shallow hydrothermal sources. This is likely due to a shorter residence time of surface water masses combined with several biogeochemical processes at play (precipitation, scavenging, biological uptake, photoreduction). This study clearly highlights the role of shallow hydrothermal sources on the DFe cycle within the Tonga-Kermadec arc where a strong link to biological activity in surface waters can be assessed, despite the small but significant fraction of DFe ultimately stabilized. It also emphasizes the need to consider the impact of these sources for a better understanding of the global iron cycle.

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Tilliette C., Taillandier V., Bouruet‐aubertot P., Grima Nicolas, Maes Christophe, Montanes M., Sarthou Geraldine, Vorrath M‐e., Arnone V., Bressac M., González‐santana D., Gazeau F., Guieu C. (2022). Dissolved iron patterns impacted by shallow hydrothermal sources along a transect through the Tonga‐Kermadec arc. Global Biogeochemical Cycles, 36(7), e2022GB007363 (27p.). Publisher's official version : https://doi.org/10.1029/2022GB007363 , Open Access version : https://archimer.ifremer.fr/doc/00782/89400/