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  • PANGAEA  (222)
  • ACS (American Chemical Society)  (3)
  • ASLO (Association for the Sciences of Limnology and Oceanography)  (2)
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Years
  • 1
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    Shallow gas migration along hydrocarbon wells – An unconsidered, anthropogenic source of biogenic methane in the North Sea (2017)
    ACS (American Chemical Society)
    In:  Environmental Science & Technology, 51 (17). pp. 10262-10268.
    Details
    Publication Date: 2020-02-06
    Description: Shallow gas migration along hydrocarbon wells constitutes a potential methane emission pathway that currently is not recognized in any regulatory framework or greenhouse gas inventory. Recently, the first methane emission measurements at three abandoned offshore wells in the Central North Sea (CNS) were conducted showing that considerable amounts of biogenic methane originating from shallow gas accumulations in the overburden of deep reservoirs were released by the boreholes. Here, we identify numerous wells poking through shallow gas pockets in 3D seismic data of the CNS indicating that about one third of the wells may leak, potentially releasing a total of 3-17 kt of methane per year into the North Sea. This poses a significant contribution to the North Sea methane budget. A large fraction of this gas (~42 %) may reach the atmosphere via direct bubble transport (0-2 kt yr-1) and via diffusive exchange of methane dissolving in the surface mixed layer (1-5 kt yr-1), as indicated by numerical modeling. In the North Sea and in other hydrocarbon-prolific provinces of the world shallow gas pockets are frequently observed in the sedimentary overburden and aggregate leakages along the numerous wells drilled in those areas may be significant.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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    DOI: 10.1021/acs.est.7b02732
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Linked sediment and water-column methanotrophy at a man-made gas blowout in the North Sea: Implications for methane budgeting in seasonally stratified shallow seas (2016)
    ASLO (Association for the Sciences of Limnology and Oceanography)
    In:  Limnology and Oceanography, 61 (S1). S367-S386.
    Details
    Publication Date: 2019-02-01
    Description: Large quantities of the greenhouse gas methane (CH4) are stored in the seafloor. The flux of CH4 from the sediments into the water column and finally to the atmosphere is mitigated by a series of microbial methanotrophic filter systems of unknown efficiency at highly active CH4-release sites in shallow marine settings. Here, we studied CH4-oxidation and the methanotrophic community at a high-CH4-flux site in the northern North Sea (well 22/4b), where CH4 is continuously released since a blowout in 1990. Vigorous bubble emanation from the seafloor and strongly elevated CH4 concentrations in the water column (up to 42 µM) indicated that a substantial fraction of CH4 bypassed the highly active (up to ∼2920 nmol cm−3 d−1) zone of anaerobic CH4-oxidation in sediments. In the water column, we measured rates of aerobic CH4-oxidation (up to 498 nM d−1) that were among the highest ever measured in a marine environment and, under stratified conditions, have the potential to remove a significant part of the uprising CH4 prior to evasion to the atmosphere. An unusual dominance of the water-column methanotrophs by Type II methane-oxidizing bacteria (MOB) is partially supported by recruitment of sedimentary MOB, which are entrained together with sediment particles in the CH4 bubble plume. Our study thus provides evidence that bubble emission can be an important vector for the transport of sediment-borne microbial inocula, aiding in the rapid colonization of the water column by methanotrophic communities and promoting their persistence close to highly active CH4 point sources.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1002/lno.10388
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Effects of climate change on methane emissions from seafloor sediments in the Arctic Ocean: A review (2016)
    ASLO (Association for the Sciences of Limnology and Oceanography)
    In:  Limnology and Oceanography, 61 (S1). pp. 301-309.
    Details
    Publication Date: 2019-09-24
    Description: Large quantities of methane are stored in hydrates and permafrost within shallow marine sediments in the Arctic Ocean. These reservoirs are highly sensitive to climate warming, but the fate of methane released from sediments is uncertain. Here, we review the principal physical and biogeochemical processes that regulate methane fluxes across the seabed, the fate of this methane in the water column, and potential for its release to the atmosphere. We find that, at present, fluxes of dissolved methane are significantly moderated by anaerobic and aerobic oxidation of methane. If methane fluxes increase then a greater proportion of methane will be transported by advection or in the gas phase, which reduces the efficiency of the methanotrophic sink. Higher freshwater discharge to Arctic shelf seas may increase stratification and inhibit transfer of methane gas to surface waters, although there is some evidence that increased stratification may lead to warming of sub-pycnocline waters, increasing the potential for hydrate dissociation. Loss of sea-ice is likely to increase wind speeds and seaair exchange of methane will consequently increase. Studies of the distribution and cycling of methane beneath and within sea ice are limited, but it seems likely that the sea-air methane flux is higher during melting in seasonally ice-covered regions. Our review reveals that increased observations around especially the anaerobic and aerobic oxidation of methane, bubble transport, and the effects of ice cover, are required to fully understand the linkages and feedback pathways between climate warming and release of methane from marine sediments.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1002/lno.10307
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Simulating and Quantifying Multiple Natural Subsea CO2 Seeps at Panarea Island (Aeolian Islands, Italy) as a Proxy for Potential Leakage from Subseabed Carbon Storage Sites (2019)
    ACS (American Chemical Society)
    In:  Environmental Science & Technology, 53 (17). pp. 10258-10268.
    Details
    Publication Date: 2022-01-31
    Description: Carbon dioxide (CO2) capture and storage (CCS) has been discussed as a potentially significant mitigation option for the ongoing climate warming. Natural CO2 release sites serve as natural laboratories to study subsea CO2 leakage in order to identify suitable analytical methods and numerical models to develop best-practice procedures for the monitoring of subseabed storage sites. We present a new model of bubble (plume) dynamics, advection-dispersion of dissolved CO2, and carbonate chemistry. The focus is on a medium-sized CO2 release from 294 identified small point sources around Panarea Island (South-East Tyrrhenian Sea, Aeolian Islands, Italy) in water depths of about 40–50 m. This study evaluates how multiple CO2 seep sites generate a temporally variable plume of dissolved CO2. The model also allows the overall flow rate of CO2 to be estimated based on field measurements of pH. Simulations indicate a release of ∼6900 t y–1 of CO2 for the investigated area and highlight an important role of seeps located at 〉20 m water depth in the carbon budget of the Panarea offshore gas release system. This new transport-reaction model provides a framework for understanding potential future leaks from CO2 storage sites.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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    DOI: 10.1021/acs.est.9b02131
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Production Method under Surveillance: Laboratory Pilot-Scale Simulation of CH 4 –CO 2 Exchange in a Natural Gas Hydrate Reservoir (2021)
    ACS (American Chemical Society)
    Details
    Publication Date: 2024-02-07
    Description: The "guest exchange"of methane (CH4) by carbon dioxide (CO2) in naturally occurring gas hydrates is seen as a possibility to concurrently produce CH4 and sequester CO2. Presently, process evaluation is based on CH4-CO2 exchange yields of small-or medium-scale laboratory experiments, mostly neglecting mass and heat transfer processes. This work investigates process efficiencies in two large-scale experiments (210 L sample volume) using fully water-saturated, natural reservoir conditions and a gas hydrate saturation of 50%. After injecting 50 kg of heated CO2 discontinuously (E1) and continuously (E2) and a subsequent soaking period, the reservoir was depressurized discontinuously. It was monitored using electrical resistivity, temperature and pressure sensors, and fluid flow and gas composition measurements. Phase and component inventories were analyzed based on mass and volume balances. The total CH4 production during CO2 injection was only 5% of the initial CH4 inventory. Prior to CO2 breakthrough, the produced CH4 roughly equaled dissolved CH4 in the produced pore water, which balanced the volume of the injected CO2. After CO2 breakthrough, CH4 ratios in the released CO2 quickly dropped to 2.0-0.5 vol %. The total CO2 retention was the highest just before the CO2 breakthrough and higher in E1 where discontinuous injection improved the distribution of injected CO2 and subsequent mixed hydrate formation. The processes were improved by the succession of CO2 injection by controlled degassing at stability limits below that of the pure CH4 hydrate, particularly in experiment E2. Here, a more heterogeneous distribution of liquid CO2 and larger availability of free water led to smaller initial degassing of liquid CO2. This allowed for quick re-formation of mixed gas hydrates and CH4 ratios of 50% in the produced gases. The experiments demonstrate the importance of fluid migration patterns, heat transport, sample inhomogeneity, and secondary gas hydrate formation in water-saturated sediments.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    The SUGAR Toolbox - A library of numerical algorithms and data for modelling of gas hydrate systems and marine environments (2013)
    PANGAEA
    In:  EPIC3Bremerhaven, PANGAEA
    Details
    Publication Date: 2015-05-11
    Repository Name: EPIC Alfred Wegener Institut
    Type: PANGAEA Documentation , notRev
    Format: application/zip
    Format: application/zip
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    PAPER (OA)
  • 7
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    Stable oxygen and hydrogen isotopic composition of pore water (δ18O-H2O; δ2H-H2O) prepared from MeBo core GeoB22603-1 recovered from the Danube Deep-Sea Fan (2020)
    PANGAEA
    Details
    Publication Date: 2023-04-27
    Keywords: Black Sea; Center for Marine Environmental Sciences; Danube deep sea fan; DEPTH, sediment/rock; Device type; gas hydrate; GeoB22603-1; light hydrocarbons; M142; M142_03-1; MARUM; MeBo200; Meteor (1986); Methane; Method/Device of event; Optional event label; pore water; RV Meteor; Sample type; Submarine Gas Hydrate Resources; SUGAR; SUGAR project; δ18O, water; δ Deuterium, water
    Type: Dataset
    Format: text/tab-separated-values, 68 data points
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    DATA PANGAEA
  • 8
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    Stable oxygen and hydrogen isotopic composition of pore water (δ18O-H2O; δ2H-H2O) prepared from MeBo core GeoB22620-1 recovered from the Danube Deep-Sea Fan (2020)
    PANGAEA
    Details
    Publication Date: 2023-04-27
    Keywords: Black Sea; Center for Marine Environmental Sciences; Danube deep sea fan; DEPTH, sediment/rock; Device type; gas hydrate; GeoB22620-1; light hydrocarbons; M142; M142_21-1; MARUM; MeBo200; Meteor (1986); Methane; Method/Device of event; Optional event label; pore water; RV Meteor; Sample type; Submarine Gas Hydrate Resources; SUGAR; SUGAR project; δ18O, water; δ Deuterium, water
    Type: Dataset
    Format: text/tab-separated-values, 12 data points
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    DATA PANGAEA
  • 9
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    Stable oxygen and hydrogen isotopic composition of pore water (δ18O-H2O; δ2H-H2O) prepared from MeBo core GeoB22605-1 recovered from the Danube Deep-Sea Fan (2020)
    PANGAEA
    Details
    Publication Date: 2023-04-27
    Keywords: Black Sea; Center for Marine Environmental Sciences; Danube deep sea fan; DEPTH, sediment/rock; Device type; gas hydrate; GeoB22605-1; light hydrocarbons; M142; M142_06-1; MARUM; MeBo200; Meteor (1986); Methane; Method/Device of event; Optional event label; pore water; RV Meteor; Sample type; Submarine Gas Hydrate Resources; SUGAR; SUGAR project; δ18O, water; δ Deuterium, water
    Type: Dataset
    Format: text/tab-separated-values, 52 data points
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    DATA PANGAEA
  • 10
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    Mineralogical, geochemical, and lipid biomarker study of cabonate precipitates at station GeoB9908-1
    PANGAEA
    In:  Supplement to: Bahr, André; Pape, Thomas; Bohrmann, Gerhard; Mazzini, Adriano; Haeckel, Matthias; Reitz, Anja; Ivanov, Michael (2009): Authigenic carbonate precipitates from the NE Black Sea: a mineralogical, geochemical, and lipid biomarker study. International Journal of Earth Sciences, 98, 677-695, https://doi.org/10.1007/s00531-007-0264-1
    Details
    Publication Date: 2023-05-12
    Description: Carbonate precipitates recovered from 2,000 m water depth at the Dolgovskoy Mound (Shatsky Ridge, north eastern Black Sea) were studied using mineralogical, geochemical and lipid biomarker analyses. The carbonates differ in shape from simple pavements to cavernous structures with thick microbial mats attached to their lower side and within cavities. Low d13C values measured on carbonates (-41 to -32 per mill V-PDB) and extracted lipid biomarkers indicate that anaerobic oxidation of methane (AOM) played a crucial role in precipitating these carbonates. The internal structure of the carbonates is dominated by finely laminated coccolith ooze and homogeneous clay layers, both cemented by micritic high-magnesium calcite (HMC), and pure, botryoidal, yellowish low-magnesium calcite (LMC) grown in direct contact to microbial mats. d18O measurements suggest that the authigenic HMC precipitated in equilibrium with the Black Sea bottom water while the yellowish LMC rims have been growing in slightly 18O-depleted interstitial water. Although precipitated under significantly different environmental conditions, especially with respect to methane availability, all analysed carbonate samples show lipid patterns that are typical for ANME-1 dominated AOM consortia, in the case of the HMC samples with significant contributions of allochthonous components of marine and terrestrial origin, reflecting the hemipelagic nature of the primary sediment.
    Keywords: BS346GR; Center for Marine Environmental Sciences; Dolgovskoy mound; GeoB9908-1; MARUM; Professor Logachev; Television-Grab; TTR-15; TVG
    Type: Dataset
    Format: application/zip, 4 datasets
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    DATA PANGAEA
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