Iron Biogeochemistry in the High Latitude North Atlantic Ocean

• Published in: Scientific Reports
• Main Authors: Achterberg, Eric, Steigenberger, Sebastian, Marsay, Chris, Le Moigne, Frédéric A.C., Painter, Stuart, Baker, Alex, Connelly, Douglas, Moore, C. Mark, Tagliabue, Alessandro, Tanhua, Toste
• Other Authors: National Oceanography Centre Southampton (NOC), University of Southampton, Helmholtz Centre for Ocean Research Kiel (GEOMAR), Skidaway Institute of Oceanography, Institute of Oceanography, Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, United Kingdom, SCHOOL OF ENVIRONMENTAL SCIENCES UNIVERSITY OF LIVERPOOL GBR, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Reykjanes; Eyjafjallajökull; Iceland; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-02960682; https://hal.archives-ouvertes.fr/hal-02960682/document; https://hal.archives-ouvertes.fr/hal-02960682/file/s41598-018-19472-1.pdf; https://doi.org/10.1038/s41598-018-19472-1

International audience Iron (Fe) is an essential micronutrient for marine microbial organisms, and low supply controls productivity in large parts of the world's ocean. The high latitude North Atlantic is seasonally Fe limited, but Fe distributions and source strengths are poorly constrained. Surface ocean dissolved Fe (DFe) concentrations were low in the study region (<0.1 nM) in summer 2010, with significant perturbations during spring 2010 in the Iceland Basin as a result of an eruption of the Eyjafjallajökull volcano (up to 2.5 nM DFe near Iceland) with biogeochemical consequences. Deep water concentrations in the vicinity of the Reykjanes Ridge system were influenced by pronounced sediment resuspension, with indications for additional inputs by hydrothermal vents, with subsequent lateral transport of Fe and manganese plumes of up to 250-300 km. Particulate Fe formed the dominant pool, as evidenced by 4-17 fold higher total dissolvable Fe compared with DFe concentrations, and a dynamic exchange between the fractions appeared to buffer deep water DFe. Here we show that Fe supply associated with deep winter mixing (up to 103 nmol m −2 d −1) was at least ca. 4-10 times higher than atmospheric deposition, diffusive fluxes at the base of the summer mixed layer, and horizontal surface ocean fluxes.