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  • Alfred-Wegener-Institut für Polar- und Meeresforschung  (4)
  • American Chemistry Society  (3)
  • 1
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    Reactivity of inorganic Mn and Mn Desferrioxamine B with O2, O2-and H2O2in seawater (2013)
    American Chemistry Society
    In:  Environmental Science & Technology, 47 (18). pp. 10257-10265.
    Details
    Publikationsdatum: 2019-09-23
    Beschreibung: Manganese (Mn) is a required element for oceanic phytoplankton as it plays a critical role in photosynthesis, through its unique redox chemistry, as the active site in photosystem II and in enzymes that act as defences against reactive oxygen species (ROS), most notably for protection against superoxide (O2-), through the action of superoxide dismutase (SOD), and against hydrogen peroxide (H2O2) via peroxidases and catalases. The distribution and redox speciation of Mn in the ocean is also apparently controlled by reactions with ROS. Here we examine the connections between ROS and dissolved Mn species in the upper ocean using field and laboratory experimental data. Our results suggest it is unlikely that significant concentrations of Mn(III) are produced in the euphotic zone, as in the absence of evidence for the existence of strong Mn(III) ligands, Mn(II) reacts with O2- to form the short lived transient manganous superoxide, MnO2+, which may react rapidly with other redox species in a similar manner to O2-. Experiments with the strong Mn(III) chelator, desferrioxamine B (DFB), in seawater indicated that the Mn(III) species is unlikely to form, as the pre-cursor Mn(II) complex under natural ambient conditions due to the high side reaction of DFB with Ca.
    Materialart: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
    DOI: 10.1021/es4016603
    Standort Signatur Einschränkungen Verfügbarkeit
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    OceanRep: Artikel in einer Fachzeitschrift - begutachtet
  • 2
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    Pathways of Superoxide (O2-) decay in the Eastern Tropical North Atlantic (2013)
    American Chemistry Society
    In:  Environmental Science & Technology, 47 (18). pp. 10249-10256.
    Details
    Publikationsdatum: 2019-09-23
    Beschreibung: Superoxide (O2-: IUPAC name dioxide (•1−)) is an important transient reactive oxygen species (ROS) in the ocean formed as an intermediate in the redox transformation of oxygen (O2) into hydrogen peroxide (H2O2) and vice versa. This highly reactive and very short-lived radical anion can be produced both via photochemical and biological processes in the ocean. In this paper we examine the decomposition rate of O2- throughout the water column, using new data collected in the Eastern Tropical North Atlantic (ETNA) Ocean. For this approach we applied a semi factorial experimental design, to identify and quantify the pathways of the major identified sinks in the ocean. In this work we occupied 6 stations, 2 on the West African continental shelf and 4 open ocean stations, including the CVOO time series site adjacent to Cape Verde. Our results indicate that in the surface ocean, impacted by Saharan aerosols and sediment resuspension, the main decay pathways for superoxide is via reactions with Mn(II) and organic matter.
    Materialart: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1021/es401658t
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
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    H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 dynamics during a mesoscale iron enrichment in the Southern Ocean (2005)
    Alfred-Wegener-Institut für Polar- und Meeresforschung
    In:  In: The Expeditions ANTARKTIS XXI/3-4-5 of the Research Vessel "Polarstern" in 2004 = Die Expeditionen ANTARKTIS XXI/3-4-5 des Forschungsschiffes "Polarstern" 2004. , ed. by Smetacek, V., Bathmann, U. and Helmke, E. Berichte zur Polar- und Meeresforschung = Reports on Polar and Marine Research, 500 . Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven, pp. 46-50.
    Details
    Publikationsdatum: 2012-02-23
    Materialart: Book chapter , PeerReviewed
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
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    Temporal changes in iron specification during mesoscale iron enrichment experiment (2005)
    Alfred-Wegener-Institut für Polar- und Meeresforschung
    In:  In: The Expeditions ANTARKTIS XXI/3-4-5 of the Research Vessel "Polarstern" in 2004 = Die Expeditionen ANTARKTIS XXI/3-4-5 des Forschungsschiffes "Polarstern" 2004. , ed. by Smetacek, V., Bathmann, U. and Helmke, E. Berichte zur Polar- und Meeresforschung = Reports on Polar and Marine Research, 500 . Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven, pp. 50-55.
    Details
    Publikationsdatum: 2013-02-18
    Materialart: Book chapter , PeerReviewed
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    OceanRep: Buchkapitel
  • 5
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    Changes in the speciation and biogeochemical cycling of other trace metals during EIFeX (2005)
    Alfred-Wegener-Institut für Polar- und Meeresforschung
    In:  In: The Expeditions ANTARKTIS XXI/3-4-5 of the Research Vessel "Polarstern" in 2004 = Die Expeditionen ANTARKTIS XXI/3-4-5 des Forschungsschiffes "Polarstern" 2004. , ed. by Smetacek, V., Bathmann, U. and Helmke, E. Berichte zur Polar- und Meeresforschung = Reports on Polar and Marine Research, 500 . Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven, pp. 55-58.
    Details
    Publikationsdatum: 2013-02-18
    Materialart: Book chapter , PeerReviewed
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    OceanRep: Buchkapitel
  • 6
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    Surface-active organic matter in the upper water column during EIFeX, a mesoscale open ocean iron enrichment experiment in the Southern Ocean (2005)
    Alfred-Wegener-Institut für Polar- und Meeresforschung
    In:  In: The Expeditions ANTARKTIS XXI/3-4-5 of the Research Vessel "Polarstern" in 2004 = Die Expeditionen ANTARKTIS XXI/3-4-5 des Forschungsschiffes "Polarstern" 2004. , ed. by Smetacek, V., Bathmann, U. and Helmke, E. Berichte zur Polar- und Meeresforschung = Reports on Polar and Marine Research, 500 . Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven, pp. 59-61.
    Details
    Publikationsdatum: 2013-02-18
    Materialart: Book chapter , PeerReviewed
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    OceanRep: Buchkapitel
  • 7
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    Superoxide Decay Kinetics in the Southern Ocean (2010)
    American Chemistry Society
    In:  Environmental Science & Technology, 44 (1). pp. 191-196.
    Details
    Publikationsdatum: 2019-09-23
    Beschreibung: Measurements of superoxide (O(2)(-)) reaction kinetics were made during a transect with the research icebreaker Polarstern (ANT24-3) in the Antarctic through the Drake Passage in austral autumn 2008. Our sampling strategy was designed to investigate the sinks of superoxide in Polar waters; principally through reactions with dissolved organic matter (DOM) or metals (copper and iron). We modified an existing chemiluminescence flow injection system using methyl Cypridina luciferin analog (MCLA) for the detection of O(2)(-) and added O(2)(-) using KO(2) as the source. Our results indicate that O(2)(-) in ambient seawater had a half-life ranging from 9.3 to 194 s. DTPA additions to seawater, to remove the effects of reactions with metals, revealed O(2)(-) decay rates consistent with a second order reaction, indicating that the dismutation reaction dominated and that reactions with DOM were not significant. Titrations of seawater by the addition of nanomolar amounts of iron or copper revealed the importance of organic chelation of Fe and/or Cu in controlling the reactivity with O(2)(-). Throughout the water column reactions with Cu appeared to be the major sink for superoxide in the Southern Ocean. This new strategy suggests an alternative approach for speciation measurements of Fe and Cu in seawater.
    Materialart: Article , PeerReviewed
    Format: text
    DOI: 10.1021/es901766r
    Standort Signatur Einschränkungen Verfügbarkeit
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