title: The distribution of dissolved iron in the West Atlantic Ocean.
abstract: Iron (Fe) is an essential trace element for marine life. Extremely low Fe concentrations limit primary production and nitrogen fixation in large parts of the oceans and consequently influence ocean ecosystem functioning. The importance of Fe for ocean ecosystems makes Fe one of the core chemical trace elements in the international GEOTRACES program. Despite the recognized importance of Fe, our present knowledge of its supply and biogeochemical cycle has been limited by mostly fragmentary datasets. Here, we present highly accurate dissolved Fe (DFe) values measured at an unprecedented high intensity (1407 samples) along the longest full ocean depth transect (17,500 kilometers) covering the entire western Atlantic Ocean. DFe measurements along this transect unveiled details about the supply and cycling of Fe. External sources of Fe identified included off-shelf and river supply, hydrothermal vents and aeolian dust. Nevertheless, vertical processes such as the recycling of Fe resulting from the remineralization of sinking organic matter and the removal of Fe by scavenging still dominated the distribution of DFe. In the northern West Atlantic Ocean, Fe recycling and lateral transport from the eastern tropical North Atlantic Oxygen Minimum Zone (OMZ) dominated the DFe-distribution. Finally, our measurements showed that the North Atlantic Deep Water (NADW), the major driver of the so-called ocean conveyor belt, contains excess DFe relative to phosphate after full biological utilization and is therefore an important source of Fe for biological production in the global ocean.
authors: Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, Den Burg, the Netherlands.
authors: Micha J A
authors: MJ
authors: Rijkenberg
authors: Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, Den Burg, the Netherlands; Department of Chemistry, University of Otago, Dunedin, New Zealand.
authors: Rob
authors: R
authors: Middag
authors: Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, Den Burg, the Netherlands.
authors: Patrick
authors: P
authors: Laan
authors: Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, Den Burg, the Netherlands.
authors: Loes J A
authors: LJ
authors: Gerringa
authors: Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, Den Burg, the Netherlands.
authors: Hendrik M
authors: HM
authors: van Aken
authors: Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, Den Burg, the Netherlands.
authors: Véronique
authors: V
authors: Schoemann
authors: Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, Den Burg, the Netherlands.
authors: Jeroen T M
authors: JT
authors: de Jong
authors: Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, Den Burg, the Netherlands; Department of Ocean Ecosystems, University of Groningen, Groningen, the Netherlands.
authors: Hein J W
authors: HJ
authors: de Baar
mesh_terms: D001267:Atlantic Ocean; D007501:Iron / Q000032:analysis*
chemical_list: D007501:Iron