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  • 2015-2019  (26)
  • 2018  (26)
Publikationsart
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  • 2015-2019  (26)
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  • 1
    Publikationsdatum: 2021-02-08
    Beschreibung: The manganese nodule belt within the Clarion and Clipperton Fracture Zones (CCZ) in the abyssal NE Pacific Ocean is characterized by numerous seamounts, low organic matter (OM) depositional fluxes and meter-scale oxygen penetration depths (OPD) into the sediment. The region hosts contract areas for the exploration of polymetallic nodules and Areas of Particular Environmental Interest (APEI) as protected areas. In order to assess the impact of potential mining on these deep-sea sediments and ecosystems, a thorough determination of the natural spatial variability of depositional and geochemical conditions as well as biogeochemical processes and element fluxes in the different exploration areas is required. Here, we present a comparative study on (1) sedimentation rates and bioturbation depths, (2) redox zonation of the sediments and element fluxes as well as (3) rates and pathways of biogeochemical reactions at six sites in the eastern CCZ. The sites are located in four European contract areas and in the APEI3. Our results demonstrate that the natural spatial variability of depositional and (bio)geochemical conditions in this deep-sea sedimentary environment is much larger than previously thought. We found that the OPD varies between 1 and 4.5 m, while the sediments at two sites are oxic throughout the sampled interval (7.5 m depth). Below the OPD, manganese and nitrate reduction occur concurrently in the suboxic zone with pore-water Mn2+ concentrations of up to 25 µM. The thickness of the suboxic zone extends over depth intervals of less than 3 m to more than 8 m. Our data and the applied transport-reaction model suggest that the extension of the oxic and suboxic zones is ultimately determined by the (1) low flux of particulate organic carbon (POC) of 1–2 mg Corg m−2 d−1 to the seafloor, (2) low sedimentation rates between 0.2 and 1.15 cm kyr−1 and (3) oxidation of pore-water Mn2+ at depth. The diagenetic model reveals that aerobic respiration is the main biogeochemical process driving OM degradation. Due to very low POC fluxes of 1 mg Corg m−2 d−1 to the seafloor at the site investigated in the protected APEI3 area, respiration rates are twofold lower than at the other study sites. Thus, the APEI3 site does not represent the (bio)geochemical conditions that prevail in the other investigated sites located in the European contract areas. Lateral variations in surface water productivity are generally reflected in the POC fluxes to the seafloor across the various areas but deviate from this trend at two of the study sites. We suggest that the observed spatial variations in depositional and (bio)geochemical conditions result from differences in the degree of degradation of OM in the water column and heterogeneous sedimentation patterns caused by the interaction of bottom water currents with seafloor topography.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    facet.materialart.
    Unbekannt
    PANGAEA
    In:  Supplement to: Volz, Jessica B; Mogollón, José M; Geibert, Walter; Martínez Arbizu, Pedro; Koschinsky, Andrea; Kasten, Sabine (2018): Natural spatial variability of depositional conditions, biogeochemical processes and element fluxes in sediments of the eastern Clarion-Clipperton Zone, Pacific Ocean. Deep Sea Research Part I: Oceanographic Research Papers, 140, 159-172, https://doi.org/10.1016/j.dsr.2018.08.006
    Publikationsdatum: 2023-03-16
    Beschreibung: The manganese nodule belt within the Clarion and Clipperton Fracture Zones (CCZ) in the abyssal NE Pacific Ocean is characterized by numerous seamounts, low organic matter (OM) depositional fluxes and meter-scale oxygen penetration depths (OPD) into the sediment. The region hosts contract areas for the exploration of polymetallic nodules and Areas of Particular Environmental Interest (APEI) as protected areas. In order to assess the impact of potential mining on these deep-sea sediments and ecosystems, a thorough determination of the natural spatial variability of depositional and geochemical conditions as well as biogeochemical processes and element fluxes in the different exploration areas is required. Here, we present a comparative study on (1) sedimentation rates and bioturbation depths, (2) redox zonation of the sediments and element fluxes as well as (3) rates and pathways of biogeochemical reactions at six sites in the eastern CCZ. The sites are located in four European contract areas and in the APEI3. Our results demonstrate that the natural spatial variability of depositional and (bio)geochemical conditions in this deep-sea sedimentary environment is much larger than previously thought. We found that the OPD varies between 1 and 4.5 m, while the sediments at two sites are oxic throughout the sampled interval (7.5 m depth). Below the OPD, manganese and nitrate reduction occur concurrently in the suboxic zone with pore-water Mn2+ concentrations of up to 25 µM. The thickness of the suboxic zone extends over depth intervals of less than 3 m to more than 8 m. Our data and the applied transport-reaction model suggest that the extension of the oxic and suboxic zones is ultimately determined by the (1) low flux of particulate organic carbon (POC) of 1–2 mg Corg m−2 d−1 to the seafloor, (2) low sedimentation rates between 0.2 and 1.15 cm kyr−1 and (3) oxidation of pore-water Mn2+ at depth. The diagenetic model reveals that aerobic respiration is the main biogeochemical process driving OM degradation. Due to very low POC fluxes of 1 mg Corg m−2 d−1 to the seafloor at the site investigated in the protected APEI3 area, respiration rates are twofold lower than at the other study sites. Thus, the APEI3 site does not represent the (bio)geochemical conditions that prevail in the other investigated sites located in the European contract areas. Lateral variations in surface water productivity are generally reflected in the POC fluxes to the seafloor across the various areas but deviate from this trend at two of the study sites. We suggest that the observed spatial variations in depositional and (bio)geochemical conditions result from differences in the degree of degradation of OM in the water column and heterogeneous sedimentation patterns caused by the interaction of bottom water currents with seafloor topography.
    Schlagwort(e): AWI_MarGeoChem; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Marine Geochemistry @ AWI
    Materialart: Dataset
    Format: application/zip, 23 datasets
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Publikationsdatum: 2024-02-02
    Schlagwort(e): AWI_MarGeoChem; DEPTH, sediment/rock; Event label; GC; GC5; Gravity corer; ICP-OES, Thermo Scientific, IRIS Intrepid; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Manganese; Marine Geochemistry @ AWI; MUC; MultiCorer; Nitrate; North Pacific Ocean; Seal QuAAtro SFA Analyzer, Seal Analytical, 800 TM; SO239; SO239_165-1; SO239_167-1; Sonne_2
    Materialart: Dataset
    Format: text/tab-separated-values, 121 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Publikationsdatum: 2024-02-02
    Schlagwort(e): AWI_MarGeoChem; CTD/Rosette; CTD6; CTD-RO; DEPTH, sediment/rock; Depth comment; Event label; GC; GC2; Gravity corer; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Marine Geochemistry @ AWI; Multicorer with television; North Pacific Ocean; Oxygen; Oxygen microsensor, Clark type (Revsbech, 1989); SO239; SO239_56-1; SO239_62-1; SO239_66-1; Sonne_2; TVMUC
    Materialart: Dataset
    Format: text/tab-separated-values, 207 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Publikationsdatum: 2024-02-02
    Schlagwort(e): AGE; Age, comment; APEI3; Area of Particular Environmental Interest 3; AWI_MarGeoChem; DEPTH, sediment/rock; Error, absolute; ICP-SF-MS, Thermo Scientific, Element 2; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Marine Geochemistry @ AWI; MUC; MultiCorer; Protactinium-231 excess; SO239; SO239_199-1; Sonne_2; Thorium-230 excess; Thorium-230 excess/Protactinium-231 excess activity ratio
    Materialart: Dataset
    Format: text/tab-separated-values, 96 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Publikationsdatum: 2024-02-02
    Schlagwort(e): AWI_MarGeoChem; DEPTH, sediment/rock; Event label; GC; GC6; Gravity corer; ICP-OES, Thermo Scientific, IRIS Intrepid; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Manganese; Marine Geochemistry @ AWI; MUC; MultiCorer; Nitrate; North Pacific Ocean; Seal QuAAtro SFA Analyzer, Seal Analytical, 800 TM; SO239; SO239_174-1; SO239_175-1; Sonne_2
    Materialart: Dataset
    Format: text/tab-separated-values, 112 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Publikationsdatum: 2024-02-02
    Schlagwort(e): AWI_MarGeoChem; DEPTH, sediment/rock; Event label; GC; Gravity corer; ICP-OES, Thermo Scientific, IRIS Intrepid; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Manganese; Marine Geochemistry @ AWI; MUC; MultiCorer; Nitrate; North Pacific Ocean; Seal QuAAtro SFA Analyzer, Seal Analytical, 800 TM; SO239; SO239_84-1; SO239_87-1; Sonne_2
    Materialart: Dataset
    Format: text/tab-separated-values, 134 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Publikationsdatum: 2024-02-02
    Schlagwort(e): AWI_MarGeoChem; CTD/Rosette; CTD-RO; DEPTH, sediment/rock; Depth comment; Event label; GC; GC4; Gravity corer; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Marine Geochemistry @ AWI; MUC; MultiCorer; North Pacific Ocean; Oxygen; Oxygen microsensor, Clark type (Revsbech, 1989); SO239; SO239_110-1; SO239_121-1; SO239_122-2; Sonne_2
    Materialart: Dataset
    Format: text/tab-separated-values, 208 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Publikationsdatum: 2024-02-02
    Schlagwort(e): AWI_MarGeoChem; Carbon, organic, total; Carbon-Sulfur Determinator, ELTRA CS-2000; DEPTH, sediment/rock; Event label; GC; GC2; Gravity corer; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Marine Geochemistry @ AWI; Multicorer with television; North Pacific Ocean; SO239; SO239_62-1; SO239_66-1; Sonne_2; TVMUC
    Materialart: Dataset
    Format: text/tab-separated-values, 69 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Publikationsdatum: 2024-02-02
    Schlagwort(e): APEI3; Area of Particular Environmental Interest 3; AWI_MarGeoChem; Carbon, organic, total; Carbon-Sulfur Determinator, ELTRA CS-2000; DEPTH, sediment/rock; Event label; GC; GC7; Gravity corer; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Marine Geochemistry @ AWI; MUC; MultiCorer; SO239; SO239_194-1; SO239_199-1; Sonne_2
    Materialart: Dataset
    Format: text/tab-separated-values, 54 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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