Sources of dissolved iron to oxygen minimum zone waters on the Senegalese continental margin in the tropical North Atlantic Ocean: Insights from iron isotopes

• Published in: Geochimica et Cosmochimica Acta
• Main Authors: Klar, J. K., Schlosser, C., Milton, J. A., Woodward, E. M. S., Lacan, F., Parkinson, I. J., Achterberg, E. P., James, R.H.
• Other Authors: National Oceanography Centre Southampton (NOC), University of Southampton, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Helmholtz Centre for Ocean Research Kiel (GEOMAR), School of Earth Sciences Bristol, University of Bristol Bristol
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: tropical Atlantic Ocean; iron isotopes; oxygen minimum zone; benthic iron; remineralisation; dissolved aluminium; dust; GEOTRACES; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; North Atlantic
• Online Access: https://hal.science/hal-03771965; https://hal.science/hal-03771965/document; https://hal.science/hal-03771965/file/GCA-S-17-00837%282%29.pdf; https://doi.org/10.1016/j.gca.2018.02.031

International audience Oxygen minimum zones (OMZs) cover extensive areas of eastern boundary ocean regions and play an important role in the cycling of the essential micronutrient iron (Fe). The isotopic composition of dissolved Fe (dFe) in shelf and slope waters on the Senegalese margin was determined to investigate the processes leading to enhanced dFe concentrations (up to 2 nM) in this tropical North Atlantic OMZ. Our results show that benthic sources of Fe inputs, characterised by low 56 Fe down to-0.33 and recycled in the water column by remineralisation processes. We show that regeneration of sinking organic material becomes a more important dFe source with distance from the shelf and this remineralised dFe has relatively high 56 Fe Remineralisation plays an important role in in the redistribution of dFe that is mainly supplied by benthic and atmospheric inputs, although dust loading, calculated from dissolved aluminium-2 d-1). As OMZs are expected to expand, our data provide important insights into Fe sources and Fe cycling in the tropical North Atlantic Ocean.