Lenstra Wytze K w.k.lenstra@uu.nl 0000-0003-0979-5594 Slomp Caroline P c.p.slomp@uu.nl 0000-0002-7272-0109 2021 Coastal hypoxia and eutrophication as key controls on benthic release and water column dynamics of iron and manganese dataset https://doi.org/10.1594/PANGAEA.930892 2021-04-28T14:48:13 Continental shelves are a major source of iron (Fe) and manganese (Mn) to marine waters. Here, we investigate controls on benthic release of Fe and Mn and the impact on the water column in the Baltic Sea. We find high in situ benthic release rates of dissolved Fe and Mn at seasonally hypoxic sites (bottom water oxygen between 0-63 μmol L−1) receiving high inputs of organic matter. We find that benthic Fe and Mn release is sensitive to bottom water oxygen concentrations. Benthic Fe release is likely additionally controlled by Fe-sulfur redox chemistry in the surface sediment. For Mn, benthic release correlates positively with Mn oxide availability in the surface sediment. Benthic release contributes to high dissolved Fe and Mn concentrations in the water column and is amplified by repeated cycling of Fe and Mn between the sediment and overlying water through benthic release, oxidation in the water column, deposition as metal oxides, followed by reductive dissolution. Most water column Fe ( 80%) is present in particulate form near the seafloor. In contrast to Fe, a large percentage of the Mn remains dissolved ( 50%). We show that easily reducible Fe and Mn oxides are key forms of particulate Fe and Mn in suspended matter. The Baltic Sea represents a highly eutrophic, low oxygen end-member when compared to other modern coastal systems. Our results imply that, upon continued eutrophication and deoxygenation of the coastal ocean, benthic release of dissolved Fe and Mn from continental shelves could become greater than previously thought. Lenstra Wytze K w.k.lenstra@uu.nl 0000-0003-0979-5594 Hermans Martijn m.hermans@uu.nl 0000-0003-2022-9307 Séguret Marie J M Witbaard Rob witbaard@nioz.nl Severmann Silke 0000-0002-6578-2993 Behrends Thilo 0000-0002-0728-6545 Slomp Caroline P c.p.slomp@uu.nl 0000-0002-7272-0109 2021 Coastal hypoxia and eutrophication as key controls on benthic release and water column dynamics of iron and manganese journal article Limnology and Oceanography 66(3) https://doi.org/10.1002/lno.11644 807-826 14.0895 26.305 54.975 60.0738 20.786199999999997 57.96615555555555 not specified Arkona_Basin_BY2 BY2 54.975 14.0895 Arkona Basin Water sample WS Bornholm_Basin_BY5 BY5 55.4682 15.4855 Bornholm Basin Water sample WS Gotland_Basin_311 311 57.4415 20.7248 Gotland Basin Water sample WS Gotland_Basin_BY15 BY15 57.32 20.05 Gotland Basin Water sample WS Gotland_Basin_LF1 LF1 57.9892 21.2873 Gotland Basin Water sample WS Gotland_Basin_LL19 LL19 58.8873 20.325 Gotland Basin Water sample WS Gulf_of_Finland_GOF5 GOF5 59.9517 25.1837 Gulf of Finland Water sample WS Gulf_of_Finland_JML JML 59.5887 23.625 Gulf of Finland Water sample WS Gulf_of_Finland_LL3A LL3A 60.0738 26.305 Gulf of Finland Water sample WS 139.6 CC-BY-4.0 Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/ CurationLevelB Basic curation https://wiki.pangaea.de/wiki/Curation_levels citable iron manganese GFBio author20337 author22185 author50259 author56276 author58120 author61104 author67601 curlevel20 event2970152 event2970153 event2970154 event2970155 event2970156 event2970157 event2970158 event2970159 event2970160 geocode1600 geocode1601 journal10608 license21 method11785 ref108193 term21042 term21509 term22117 term233 term23771 term49538 term50710 topotype1