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  • 1
    Online Resource
    Online Resource
    Sediment and pore water chemistry of cores 214 and 755 recovered during Meteor M72/1 and Poseidon POS317/2 cruise, northwestern Black Sea, supplementary data to: Henkel, Susann; Mogollón, José M; Nöthen, Kerstin; Franke, Christine; Bogus, Kara; Robin, Eric; Bahr, André; Blumenberg, Martin; Pape, Thomas; Seifert, Richard; März, Christian; de Lange, Gert Jan; Kasten, Sabine (2012): Diagenetic barium cycling in Black Sea sediments - A case study for anoxic marine environments. Geochimica et Cosmochimica Acta, 88, 88-105 (2012)
    Details Availability
    Keywords: Datensammlung
    Description / Table of Contents: High-resolution sedimentary records of major and minor elements (Al, Ba, Ca, Sr, Ti), total organic carbon (TOC), and profiles of pore water constituents (SO42-, CH4, Ca2+, Ba2+, Mg2+, alkalinity) were obtained for two gravity cores (core 755, 501 m water depth and core 214, 1686 m water depth) from the northwestern Black Sea. The records were examined in order to gain insight into the cycling of Ba in anoxic marine sediments characterized by a shallow sulfate-methane transition (SMT) as well as the applicability of barite as a primary productivity proxy in such a setting. The Ba records are strongly overprinted by diagenetic barite (BaSO4) precipitation and remobilization; authigenic Ba enrichments were found at both sites at and slightly above the current SMT. Transport reaction modeling was applied to simulate the migration of the SMT during the changing geochemical conditions after the Holocene seawater intrusion into the Black Sea. Based on this, sediment intervals affected by diagenetic Ba redistribution were identified. Results reveal that the intense overprint of Ba and Baxs (Ba excess above detrital average) strongly limits its correlation to primary productivity. These findings have implications for other modern and ancient anoxic basins, such as sections covering the Oceanic Anoxic Events for which Ba is frequently used as a primary productivity indicator. Our study also demonstrates the limitations concerning the use of Baxs as a tracer for downward migrations of the SMT: due to high sedimentation rates at the investigated sites, diagenetic barite fronts are buried below the SMT within a relatively short period. Thus, 'relict' barite fronts would only be preserved for a few thousands of years, if at all.〈br〉〈br〉REFERENCE:〈br〉Blumenberg, Martin; Seifert, Richard; Kasten, Sabine; Bahlmann, E; Michaelis, Walter (2009): Euphotic zone bacterioplankton sources major bacteriohopanepolyols in the Holocene Black Sea. Geochimica et Cosmochimica Acta, 73(3), 750-766
    Type of Medium: Online Resource
    Pages: 4 Datasets , Format: application/zip
    URL: http://dx.doi.org/10.1594/PANGAEA.779906
    URL: http://nbn-resolving.de/urn:nbn:de:tib-10.1594/PANGAEA.7799063
    URN: urn:nbn:de:tib-10.1594/PANGAEA.7799063
    DOI: 10.1594/PANGAEA.779906
    Language: English
    Note: This dataset is supplement to doi:10.1016/j.gca.2012.04.021 , This dataset is cited by doi:10.1016/j.gca.2008.11.005
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  • 2
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    Natural spatial variability of depositional conditions, biogeochemical processes and element fluxes in sediments of the eastern Clarion-Clipperton Zone, Pacific Ocean (2018)
    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 140 . pp. 159-172.
    Details
    Publication Date: 2021-02-08
    Description: 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.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.dsr.2018.08.006
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    A method for the calculation of anaerobic oxidation of methane rates across regional scales: an example from the Belt Seas and The Sound (North Sea–Baltic Sea transition) (2013)
    Springer
    In:  Geo-Marine Letters, 33 (4). pp. 299-310.
    Details
    Publication Date: 2017-05-19
    Description: Estimating the amount of methane in the seafloor globally as well as the flux of methane from sediments toward the ocean–atmosphere system are important considerations in both geological and climate sciences. Nevertheless, global estimates of methane inventories and rates of methane production and consumption through anaerobic oxidation in marine sediments are very poorly constrained. Tools for regionally assessing methane formation and consumption rates would greatly increase our understanding of the spatial heterogeneity of the methane cycle as well as help constrain the global methane budget. In this article, an algorithm for calculating methane consumption rates in the inner shelf is applied to the gas-rich sediments of the Belt Seas and The Sound (North Sea–Baltic Sea transition). It is based on the depth of free gas determined by hydroacoustic techniques and the local methane solubility concentration. Due to the continuous nature of shipboard hydroacoustic measurements, this algorithm captures spatial heterogeneities in methane fluxes better than geochemical analyses of point sources such as observational/sampling stations. The sensibility of the algorithm with respect to the resolution of the free gas depth measurements (2 m vs. 50 cm) is proven of minor importance (a discrepancy of 〈10%) for a small part of the study area. The algorithm-derived anaerobic methane oxidation rates compare well with previous measured and modeling studies. Finally, regional results reveal that contemporary anaerobic methane oxidation in worldwide inner-shelf sediments may be an order of magnitude lower (ca. 0.24 Tmol year–1) than previous estimates (4.6 Tmol year–1). These algorithms ultimately help improve regional estimates of anaerobic oxidation of methane rates.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1007/s00367-013-0329-z
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Diagenetic barium cycling in Black Sea sediments – A case study for anoxic marine environments (2012)
    Elsevier
    In:  Geochimica et Cosmochimica Acta, 88 . pp. 88-105.
    Details
    Publication Date: 2015-11-24
    Description: High-resolution sedimentary records of major and minor elements (Al, Ba, Ca, Sr, Ti), total organic carbon (TOC), and profiles of pore water constituents (View the MathML sourceSO42-, CH4, Ca2+, Ba2+, Mg2+, alkalinity) were obtained for two gravity cores (core 755, 501 m water depth and core 214, 1686 m water depth) from the northwestern Black Sea. The records were examined in order to gain insight into the cycling of Ba in anoxic marine sediments characterized by a shallow sulfate–methane transition (SMT) as well as the applicability of barite as a primary productivity proxy in such a setting. The Ba records are strongly overprinted by diagenetic barite (BaSO4) precipitation and remobilization; authigenic Ba enrichments were found at both sites at and slightly above the current SMT. Transport reaction modeling was applied to simulate the migration of the SMT during the changing geochemical conditions after the Holocene seawater intrusion into the Black Sea. Based on this, sediment intervals affected by diagenetic Ba redistribution were identified. Results reveal that the intense overprint of Ba and Baxs (Ba excess above detrital average) strongly limits its correlation to primary productivity. These findings have implications for other modern and ancient anoxic basins, such as sections covering the Oceanic Anoxic Events which Ba is frequently used as a primary productivity indicator. Our study also demonstrates the limitations concerning the use of Baxs as a tracer for downward migrations of the SMT: due to high sedimentation rates at the investigated sites, diagenetic barite fronts are buried below the SMT within a relatively short period. Thus, ‘relict’ barite fronts would only be preserved for a few thousands of years, if at all.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.gca.2012.04.021
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    (Appendix 1) Pore water analysis from sediment cores in the area of a landslide scar close to the airport of Nice (2017)
    PANGAEA
    Details
    Publication Date: 2023-03-14
    Keywords: Alkalinity, total; Aluminium; Ammonium; Barium; Boron; Bromide; Calcium; Chloride; Conductivity; Copper; DEPTH, sediment/rock; Event label; GC; GeoB13918; GeoB13919; GeoB13925; GeoB13926; GeoB13928; GeoB13929; GeoB13930; GeoB13934; GeoB13939; GeoB13940; GeoB13946; GeoB13952; GeoB13953; Gravity corer; Iron; Leibniz Centre for Tropical Marine Research; Lithium; Magnesium; Manganese; Oxidation reduction (RedOx) potential; pH; Phosphorus; POS386; Poseidon; Potassium; Silicon; Sodium; Strontium; Sulfate; Sulfur; Zinc; ZMT; δ18O; δ18O, standard deviation; δ Deuterium; δ Deuterium, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 5330 data points
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    DATA PANGAEA
  • 6
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    Pore water and solid phase data of two sediment cores obtained in the Makran area offshore pakistan during expedition M 74/3 in 2007 (2013)
    PANGAEA
    In:  Supplement to: Fischer, David; Mogollón, José M; Strasser, Michael; Pape, Thomas; Bohrmann, Gerhard; Fekete, Noemi; Spieß, Volkhard; Kasten, Sabine (2013): Subduction zone earthquake as potential trigger of submarine hydrocarbon seepage. Nature Geoscience, 6(8), 647-651, https://doi.org/10.1038/ngeo1886
    Details
    Publication Date: 2023-03-03
    Description: Methane, a potent greenhouse gas, is abundant in marine sediments**1, 2. Submarine seepage of methane-dominated hydrocarbons is heterogeneous in space and time, and mechanisms that can trigger episodic seep events are poorly understood**2, 3, 4. For example, critical gas pressures have been predicted to develop beneath impermeable sediments that bear gas hydrates, making them susceptible to mechanical failure and gas release**5, 6. Gas hydrates often occur in seismically active regions, but the role of earthquakes as triggers of hydrocarbon seepage through gas-hydrate-bearing sediments has been only superficially addressed**7, 8. Here we present geochemical analyses of sediment cores retrieved from the convergent margin off Pakistan. We find that a substantial increase in the upward flux of gas occurred within a few decades of a Mw 8.1 earthquake in 1945-the strongest earthquake reported for the Arabian Sea. Our seismic reflection data suggest that co-seismic shaking fractured gas-hydrate-bearing sediments, creating pathways for the free gas to migrate from a shallow reservoir within the gas hydrate stability zone into the water column. We conservatively estimate that 3.26×10**8 mol of methane have been discharged from the seep site since the earthquake. We therefore suggest that hydrocarbon seepage triggered by earthquakes needs to be considered in local and global carbon budgets at active continental margins.
    Keywords: Center for Marine Environmental Sciences; MARUM
    Type: Dataset
    Format: application/zip, 4 datasets
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    DATA PANGAEA
  • 7
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    (Appendix 3) Different saturation index analysis from sediment cores in the area of a landslide scar close to the airport of Nice (2017)
    PANGAEA
    Details
    Publication Date: 2023-03-14
    Keywords: -; DEPTH, sediment/rock; Event label; GC; GeoB13919; GeoB13925; GeoB13926; GeoB13928; GeoB13929; GeoB13930; GeoB13934; GeoB13939; GeoB13940; GeoB13946; GeoB13952; GeoB13953; Gravity corer; Leibniz Centre for Tropical Marine Research; pH; POS386; Poseidon; Saturation index; ZMT
    Type: Dataset
    Format: text/tab-separated-values, 1872 data points
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    DATA PANGAEA
  • 8
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    Pore-water manganese, nitrate and oxygen data and solid-phase radionuclide and TOC data for sediment cores taken during R/V SONNE cruise SO239 in the CCZ (2018)
    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
    Details
    Publication Date: 2023-03-16
    Description: 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.
    Keywords: AWI_MarGeoChem; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Marine Geochemistry @ AWI
    Type: Dataset
    Format: application/zip, 23 datasets
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    DATA PANGAEA
  • 9
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    Depth profiles of pore-water and solid-phase constituents, respiration rates and grain size distribution in sediments of the Clarion-Clipperton Fracture Zone
    PANGAEA
    In:  Supplement to: Mewes, Konstantin; Mogollón, José M; Picard, Aude; Rühlemann, Carsten; Kuhn, Thomas; Nöthen, Kerstin; Kasten, Sabine (2014): Impact of depositional and biogeochemical processes on small scale variations in nodule abundance in the Clarion‐Clipperton Fracture Zone. Deep Sea Research Part I: Oceanographic Research Papers, 91, 125-141, https://doi.org/10.1016/j.dsr.2014.06.001
    Details
    Publication Date: 2023-05-12
    Description: Manganese nodules of the Clarion-Clipperton Fracture Zone (CCFZ) in the NE Pacific Ocean are highly enriched in Ni, Cu, Co, Mo and rare-earth elements, and thus may be the subject of future mining operations. Elucidating the depositional and biogeochemical processes that contribute to nodule formation, as well as the respective redox environment in both, water column and sediment, supports our ability to locate future nodule deposits and evaluates the potential ecological and environmental effects of future deep-sea mining. For these purposes we evaluated the local hydrodynamics and pore-water geochemistry with respect to the nodule coverage at four sites in the eastern CCFZ. Furthermore, we carried out selective leaching experiments at these sites in order to assess the potential mobility of Mn in the solid phase, and compared them with the spatial variations in sedimentation rates. We found that the oxygen penetration depth is 180 - 300 cm at all four sites, while reduction of Mn and NO3- is only significant below the oxygen penetration depth at sites with small or no nodules on the sediment surface. At the site without nodules, potential microbial respiration rates, determined by incubation experiments using 14C-labelled acetate, are slightly higher than at sites with nodules. Leaching experiments showed that surface sediments covered with big or medium-sized nodules are enriched in mobilizable Mn. Our deep oxygen measurements and pore-water data suggest that hydrogenetic and oxic-diagenetic processes control the present-day nodule growth at these sites, since free manganese from deeper sediments is unable to reach the sediment surface. We propose that the observed strong lateral contrasts in nodule size and abundance are sensitive to sedimentation rates, which in turn, are controlled by small-scale variations in seafloor topography and bottom-water current intensity.
    Type: Dataset
    Format: application/zip, 31 datasets
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    DATA PANGAEA
  • 10
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    Pore water profile of oxygen of sediment core BIO12-60KL (2015)
    PANGAEA
    Details
    Publication Date: 2023-03-28
    Keywords: BIO12-60KL; BIONOD; DEPTH, sediment/rock; KULC; KULLENBERG corer; L Atalante; NODKUL3; North Pacific Ocean; Oxygen
    Type: Dataset
    Format: text/tab-separated-values, 170 data points
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    DATA PANGAEA
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