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  • Alfred-Wegener-Institut für Polar- und Meeresforschung  (4)
  • American Chemistry Society  (3)
  • European Marine Board  (2)
  • 1
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    American Chemistry Society
    In:  Environmental Science & Technology, 47 (18). pp. 10257-10265.
    Publication Date: 2019-09-23
    Description: 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.
    Type: Article , PeerReviewed
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  • 2
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    American Chemistry Society
    In:  Environmental Science & Technology, 47 (18). pp. 10249-10256.
    Publication Date: 2019-09-23
    Description: 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.
    Type: Article , PeerReviewed
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  • 3
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    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.
    Publication Date: 2012-02-23
    Type: Book chapter , PeerReviewed
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  • 4
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    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.
    Publication Date: 2013-02-18
    Type: Book chapter , PeerReviewed
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  • 5
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    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.
    Publication Date: 2013-02-18
    Type: Book chapter , PeerReviewed
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  • 6
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    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.
    Publication Date: 2013-02-18
    Type: Book chapter , PeerReviewed
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  • 7
    Publication Date: 2023-09-04
    Description: The sentence “every second breath you take comes from the Ocean” is commonly used in Ocean Literacy and science communication to highlight the importance of Ocean oxygen. However, despite its widespread use, it is often not phrased correctly. In contrast, awareness about the threat of the global oxygen loss in the Ocean, called deoxygenation, is low, particularly in comparison with other important stressors, such as Ocean acidification or increasing seawater temperatures. Deoxygenation is increasing in the coastal and open Ocean, primarily due to human-induced global warming and nutrient run-off from land, and projections show that the Ocean will continue losing oxygen as global warming continues. The consequences of oxygen loss in the Ocean are extensive and include decreased biodiversity, shifts in species distributions, displacement or reduction in fisheries resources, changes in biogeochemical cycling and mass mortalities. Low oxygen conditions also drive other chemical processes which produce greenhouse gases, toxic compounds and further degrade water quality. Degraded water quality directly affects marine ecosystems, but also indirectly impacts ecosystem services supporting local communities, regional economies and tourism. Although there are still gaps in our knowledge, we know enough to be very concerned about the consequences: the impacts might even be larger than from Ocean acidification or heat waves, and three out of the five global mass extinctions were linked to Ocean deoxygenation. The sense of urgency to improve Ocean health is reflected in the UN Decade of Ocean Science for Sustainable Development and the EU Mission: Restore our Ocean and Waters, and tackling the loss of oxygen in the Ocean is critical to achieving the aims of these two initiatives.
    Type: Report , NonPeerReviewed
    Format: text
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  • 8
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    American Chemistry Society
    In:  Environmental Science & Technology, 44 (1). pp. 191-196.
    Publication Date: 2019-09-23
    Description: 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.
    Type: Article , PeerReviewed
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  • 9
    Publication Date: 2023-10-21
    Description: EMB Future Science Brief No. 10 highlights the most recent science on Ocean oxygen, including causes, impacts and mitigation strategies of Ocean oxygen loss, and discusses whether “every second breath we take comes from the Ocean”. It closes with key policy, management and research recommendations to address Ocean deoxygenation and communicate more accurately about the role of the Ocean in Earth’s oxygen. The sentence “every second breath you take comes from the Ocean” is commonly used in Ocean Literacy and science communication to highlight the importance of Ocean oxygen. However, despite its widespread use, it is often not phrased correctly. In contrast, there is little awareness about the threat of the global oxygen loss in the Ocean, called deoxygenation, particularly in comparison with other important stressors, such as Ocean acidification or increasing seawater temperatures. Deoxygenation is increasing in the coastal and open Ocean, primarily due to human-induced global warming and nutrient run-off from land, and projections show that the Ocean will continue losing oxygen as global warming continues. The consequences of oxygen loss in the Ocean are extensive and include decreased biodiversity, shifts in species distributions, displacement or reduction in fisheries resources, changes in biogeochemical cycling and mass mortalities. Low oxygen conditions also drive other chemical processes which produce greenhouse gases, toxic compounds and further degrade water quality. The degraded water quality directly affects marine ecosystems, but also indirectly impacts ecosystem services supporting local communities, regional economies and tourism. Although there are still gaps in our knowledge, we know enough to be very concerned about the consequences: the impacts might even be larger than from Ocean acidification or heat waves, and three out of the five global mass extinctions were linked to Ocean deoxygenation. The sense of urgency to improve Ocean health is reflected in the UN Decade of Ocean Science for Sustainable Development (Ocean Decade) and the EU Mission: Restore our Ocean and Waters (Mission Ocean), and tackling the loss of oxygen in the Ocean is critical to achieving the aims of these two initiatives.
    Description: Published
    Description: Refereed
    Keywords: Ocean oxygen ; Deoxygenation
    Repository Name: AquaDocs
    Type: Book/Monograph/Conference Proceedings
    Format: 84pp.
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