Modeling sub‐sea permafrost in the East Siberian Arctic Shelf: The Laptev Sea region

Nicolsky, Dmitry; Romanovsky, V. E.; Romanovskii, N. N.; Kholodov, Alexander; Shakhova, Natalia; Semiletov, I. P.

doi:10.1029/2012jf002358

Cited by 91 publications

(108 citation statements)

References 54 publications

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“…sr.unh.edu/whatisarctichydro.shtml). Nicolsky et al, 2012). Moreover, the first results from offshore drilling (accomplished from the fast ice in April 2011) down to 52 m below the sea floor in the southeastern Laptev Sea showed that the sediment core was entirely unfrozen, and 8-12 • C warmer than an on-land sediment core obtained in the nearby Chay-Tumus borehole (Shakhova et al, 2014), confirming these authors' modeling results.…”

Section: Introductionsupporting

confidence: 78%

Discovery and characterization of submarine groundwater discharge in the Siberian Arctic seas: a case study in the Buor-Khaya Gulf, Laptev Sea

et al. 2017

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Abstract. It has been suggested that increasing terrestrial water discharge to the Arctic Ocean may partly occur as submarine groundwater discharge (SGD), yet there are no direct observations of this phenomenon in the Arctic shelf seas. This study tests the hypothesis that SGD does exist in the Siberian Arctic Shelf seas, but its dynamics may be largely controlled by complicated geocryological conditions such as permafrost. The field-observational approach in the southeastern Laptev Sea used a combination of hydrological (temperature, salinity), geological (bottom sediment drilling, geoelectric surveys), and geochemical ( 224 Ra, 223 Ra, 228 Ra, and 226 Ra) techniques. Active SGD was documented in the vicinity of the Lena River delta with two different operational modes. In the first system, groundwater discharges through tectonogenic permafrost talik zones was registered in both winter and summer. The second SGD mechanism was cryogenic squeezing out of brine and watersoluble salts detected on the periphery of ice hummocks in the winter. The proposed mechanisms of groundwater transport and discharge in the Arctic land-shelf system is elaborated. Through salinity vs. 224 Ra and 224 Ra/ 223 Ra diagrams, the three main SGD-influenced water masses were identified and their end-member composition was constrained. Based on simple mass-balance box models, discharge rates at sites in the submarine permafrost talik zone were 1.7×10 6 m 3 d −1 or 19.9 m 3 s −1 , which is much higher than the April discharge of the Yana River. Further studies should apply these techniques on a broader scale with the objective of elucidating the relative importance of the SGD transport vector relative to surface freshwater discharge for both water balance and aquatic components such as dissolved organic carbon, carbon dioxide, methane, and nutrients.

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Section: Introductionsupporting

confidence: 78%

Discovery and characterization of submarine groundwater discharge in the Siberian Arctic seas: a case study in the Buor-Khaya Gulf, Laptev Sea

et al. 2017

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“…The absence of glacial ice during the LGM is consistent with the existence of permafrost across much of the submarine East Siberian shelf (Romanovskii et al, 2004;Nicolsky et al, 2012), the reported absence of ice on Wrangel island during the LGM (Gaultieri et al, 2005) and the comparatively limited extent of the Kara ice sheet on the Barents Sea (Möller et al, 2015). The lack of glacial ice in the East Siberian Sea and the Kara Sea during the LGM are both ascribed to generally arid conditions due to a reduction in atmospheric moisture supply to these regions (Gaultieri et al, 2005;Möller et al, 2015).…”

Section: Timing and Association With Ice Sheets On The Siberian Shelfmentioning

confidence: 70%

“…3). In this area IB-CAO is completely based on digitized contours from the Russian bathymetric maps published by the Head Department of Navigation and Oceanography (HDNO) in 1999 and 2001 (Naryshkin, 1999(Naryshkin, , 2001. The source data of the Russian HDNO maps are not publicly available.…”

Section: Cross-shelf Troughmentioning

confidence: 99%

The De Long Trough: a newly discovered glacial trough on the East Siberian continental margin

et al. 2017

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Abstract. Ice sheets extending over parts of the East Siberian continental shelf have been proposed for the last glacial period and during the larger Pleistocene glaciations. The sparse data available over this sector of the Arctic Ocean have left the timing, extent and even existence of these ice sheets largely unresolved. Here we present new geophysical mapping and sediment coring data from the East Siberian shelf and slope collected during the 2014 SWERUS-C3 expedition (SWERUS-C3: Swedish -Russian -US Arctic Ocean Investigation of Climate-Cryosphere-Carbon Interactions). The multibeam bathymetry and chirp sub-bottom profiles reveal a set of glacial landforms that include grounding zone formations along the outer continental shelf, seaward of which lies a > 65 m thick sequence of glacio-genic debris flows. The glacial landforms are interpreted to lie at the seaward end of a glacial trough -the first to be reported on the East Siberian margin, here referred to as the De Long Trough because of its location due north of the De Long Islands. Stratigraphy and dating of sediment cores show that a drape of acoustically laminated sediments covering the glacial deposits is older than ∼ 50 cal kyr BP. This provides direct evidence for extensive glacial activity on the Siberian shelf that predates the Last Glacial Maximum and most likely occurred during the Saalian (Marine Isotope Stage (MIS) 6).

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“…However, at 74.5 • N, 118 • E, for example, the depth of permafrost saturated to at least 50 % by ice degrades from about 25 to 200 m b.s.f. (below the sea floor), a mean rate of just below 0.01 m a −1 (Nicolsky et al, 2012). Romanovskii and Hubberten (2001) show even lower rates of degradation of icebonded permafrost (defined as liquid water contents of < 5 % by weight).…”

Section: Submarine Permafrost Degradationmentioning

confidence: 99%

“…Following inundation, ice content decreases throughout submarine permafrost due to warming and the consequent thaw of pore ice. Nicolsky et al (2012) shows this as an increase in water content based on assumed freezing characteristic curves. In this model, the rate of ice melt depends on a suite of conditions during and antecedent to inundation.…”

Section: Submarine Permafrost Degradationmentioning

confidence: 99%

Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia

et al. 2016

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Abstract. Coastal erosion and flooding transform terrestrial landscapes into marine environments. In the Arctic, these processes inundate terrestrial permafrost with seawater and create submarine permafrost. Permafrost begins to warm under marine conditions, which can destabilize the sea floor and may release greenhouse gases. We report on the transition of terrestrial to submarine permafrost at a site where the timing of inundation can be inferred from the rate of coastline retreat. On Muostakh Island in the central Laptev Sea, East Siberia, changes in annual coastline position have been measured for decades and vary highly spatially. We hypothesize that these rates are inversely related to the inclination of the upper surface of submarine ice-bonded permafrost (IBP) based on the consequent duration of inundation with increasing distance from the shoreline. We compared rapidly eroding and stable coastal sections of Muostakh Island and find permafrost-table inclinations, determined using direct current resistivity, of 1 and 5 %, respectively. Determinations of submarine IBP depth from a drilling transect in the early 1980s were compared to resistivity profiles from 2011. Based on borehole observations, the thickness of unfrozen sediment overlying the IBP increased from 0 to 14 m below sea level with increasing distance from the shoreline. The geoelectrical profiles showed thickening of the unfrozen sediment overlying ice-bonded permafrost over the 28 years since drilling took place. We use geoelectrical estimates of IBP depth to estimate permafrost degradation rates since inundation. Degradation rates decreased from over 0.4 m a −1 following inundation to around 0.1 m a −1 at the latest after 60 to 110 years and remained constant at this level as the duration of inundation increased to 250 years. We suggest that long-term rates are lower than these values, as the depth to the IBP increases and thermal and porewater solute concentration gradients over depth decrease. For the study region, recent increases in coastal erosion rate and changes in benthic temperature and salinity regimes are expected to affect the depth to submarine permafrost, leading to coastal regions with shallower IBP.

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Modeling sub‐sea permafrost in the East Siberian Arctic Shelf: The Laptev Sea region

Cited by 91 publications

References 54 publications

Discovery and characterization of submarine groundwater discharge in the Siberian Arctic seas: a case study in the Buor-Khaya Gulf, Laptev Sea

Discovery and characterization of submarine groundwater discharge in the Siberian Arctic seas: a case study in the Buor-Khaya Gulf, Laptev Sea

The De Long Trough: a newly discovered glacial trough on the East Siberian continental margin

Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia

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