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  • 1
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    American Geophysical Union
    In:  EPIC3American Geophysical Union, Fall Meeting 2015, San Francisco, 2015San Francisco, American Geophysical Union
    Publication Date: 2016-10-26
    Description: Coastal erosion and relative sea-level rise inundate terrestrial permafrost with seawater and create submarine permafrost. Once flooded, permafrost begins to warm under marine conditions, which can destabilize the sea floor. The timing of inundation can be inferred from the rate of coastline retreat and the distance from the shoreline. Coastline retreat rates are inversely related to the inclination of the upper surface of submarine ice-bonded permafrost. Submarine permafrost thaw is considered to be a cause for recent observations of methane emissions from the seabed to the water column and atmosphere of the East Siberian shelf. A 52 m long core drilled from the sea ice in Buor Khaya Bay, central Laptev Sea revealed unfrozen sediment overlying ice-bonded permafrost. Dissolved methane and sulfate concentrations are inversely related along the core with higher methane and lower sulfate contents in the ice-bonded submarine permafrost relative to the overlying unfrozen sediment. The observed profiles of sediment pore water sulfate concentrations, as well as methane concentrations and methane stable carbon isotope ratios, indicate that methane from ice-bonded permafrost is oxidized at or immediately following thaw. Anaerobic oxidation of methane in the unfrozen sediment column between ice-bonded permafrost and the seabed makes it unlikely that methane from thawing submarine permafrost could reach the seabed.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
    Format: application/pdf
    Location Call Number Limitation Availability
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  • 2
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    Unknown
    American Geophysical Union
    In:  EPIC3Fall meeting, San Francisco, 2013-12-09-2013-12-13American Geophysical Union
    Publication Date: 2019-07-16
    Description: The northern permafrost region contains approximately 50% of the estimated global below-ground organic carbon pool and more than twice as much as is contained in the current atmospheric carbon pool. The sheer size of this carbon pool, together with the large amplitude of predicted arctic climate change implies that there is a high potential for global-scale feedbacks from arctic climate change if these carbon reservoirs are destabilized. Nonetheless, significant gaps exist in our current state of knowledge that prevent us from producing accurate assessments of the vulnerability of the arctic permafrost to climate change, or of the implications of future climate change for global greenhouse gas (GHG) emissions. In order o close these gaps, the key objectives of PAGE21 are: - to improve our understanding of the processes affecting the size of the arctic permafrost carbon and nitrogen pools - to produce, assemble and assess high-quality datasets in order to develop and evaluate representations of permafrost and related processes in global models, - to improve these models accordingly, - to use these models to reduce the uncertainties in feedbacks from arctic permafrost to global change. The concept of PAGE21 is to directly address these questions through a close interaction between monitoring activities, process studies and modeling on the pertinent temporal and spatial scales. PAGE21 is determined to break down the traditional barriers in permafrost sciences between observational and model-supported site studies and large-scale climate modeling.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
    Location Call Number Limitation Availability
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  • 3
    Publication Date: 2015-06-26
    Description: Submarine permafrost degradation has been invoked as a cause for recent observations of methane emissions from the seabed to the water column and atmosphere of the East Siberian shelf. Sediment drilled 52 m down from the sea ice in Buor Khaya Bay, central Laptev Sea revealed unfrozen sediment overlying ice-bonded permafrost. Methane concentrations in the overlying unfrozen sediment were low (mean 20 µM) but higher in the underlying ice-bonded submarine permafrost (mean 380 µM). In contrast, sulfate concentrations were substantially higher in the unfrozen sediment (mean 2.5 mM) than in the underlying submarine permafrost (mean 0.1 mM). Using deduced permafrost degradation rates, we calculate potential mean methane efflux from degrading permafrost of 120 mg m−2 yr−1 at this site. However, a drop of methane concentrations from 190 µM to 19 µM and a concomitant increase of methane δ13C from −63‰ to −35‰ directly above the ice-bonded permafrost suggest that methane is effectively oxidized within the overlying unfrozen sediment before it reaches the water column. High rates of methane ebullition into the water column observed elsewhere are thus unlikely to have ice-bonded permafrost as their source.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Location Call Number Limitation Availability
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