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  • 551.48  (1)
  • Center for Marine Environmental Sciences; GEOMAR; Helmholtz Centre for Ocean Research Kiel; MARUM  (1)
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  • 1
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    Isotope analysis and heat flow measurements of Maria S. Merian cruise MSM21/4 on the western Svalbard margin (2014)
    PANGAEA
    In:  Supplement to: Berndt, Christian; Feseker, Tomas; Treude, Tina; Krastel, Sebastian; Liebetrau, Volker; Niemann, Helge; Bertics, Victoria J; Dumke, Ines; Dünnbier, Karolin; Ferre, Benedicte; Graves, Carolyn; Gross, Felix; Hissmann, Karen; Hühnerbach, Veit; Krause, Stefan; Lieser, Kathrin; Schauer, Jürgen; Steinle, Lea (2014): Temporal constraints on hydrate-controlled methane seepage off Svalbard. Published Online January 2 2014, Science, https://doi.org/10.1126/science.1246298
    Details
    Publication Date: 2023-03-03
    Description: Methane hydrate is an ice-like substance that is stable at high-pressure and low temperature in continental margin sediments. Since the discovery of a large number of gas flares at the landward termination of the gas hydrate stability zone off Svalbard, there has been concern that warming bottom waters have started to dissociate large amounts of gas hydrate and that the resulting methane release may possibly accelerate global warming. Here, we can corroborate that hydrates play a role in the observed seepage of gas, but we present evidence that seepage off Svalbard has been ongoing for at least three thousand years and that seasonal fluctuations of 1-2°C in the bottom-water temperature cause periodic gas hydrate formation and dissociation, which focus seepage at the observed sites.
    Keywords: Center for Marine Environmental Sciences; GEOMAR; Helmholtz Centre for Ocean Research Kiel; MARUM
    Type: Dataset
    Format: application/zip, 29 datasets
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    DATA PANGAEA
  • 2
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    Impact of Flow Alteration and Temperature Variability on Hyporheic Exchange (2021)
    Details
    Publication Date: 2021-12-03
    Description: Coupled groundwater flow and heat transport within hyporheic zones extensively affect water, energy, and solute exchange with surrounding sediments. The local and cumulative implications of this tightly coupled process strongly depend on characteristics of drivers (i.e., discharge and temperature of the water column) and modulators (i.e., hydraulic and thermal properties of the sediment). With this in mind, we perform a systematic numerical analysis of hyporheic responses to understand how the temporal variability of river discharge and temperature affect flow and heat transport within hyporheic zones. We identify typical time series of river discharge and temperature from gauging stations along the headwater region of Mississippi River Basin, which are characterized by different degrees of flow alteration, to drive a physics-based model of the hyporheic exchange process. Our modeling results indicate that coupled groundwater flow and heat transport significantly affects the dynamic response of hyporheic zones, resulting in substantial differences in exchange rates and characteristic time scales of hyporheic exchange processes. We also find that the hyporheic zone dampens river temperature fluctuations increasingly with higher frequency of temperature fluctuations. This dampening effect depends on the system transport time scale and characteristics of river discharge and temperature variability. Furthermore, our results reveal that the flow alteration reduces the potential of hyporheic zones to act as a temperature buffer and hinders denitrification within hyporheic zones. These results have significant implications for understanding the drivers of local variability in hyporheic exchange and the implications for the development of thermal refugia and ecosystem functioning in hyporheic zones.
    Keywords: 551.48 ; hyporheic exchange ; numerical analysis
    Language: English
    Type: map
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    CITATION GEO-LEO
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