Holocene History of the Laptev Sea Continental Shelf

1974 ◽  
pp. 211-229 ◽  
Author(s):  
M. L. Holmes ◽  
J. S. Creager
Keyword(s):  
Continental Shelf ◽  
Laptev Sea ◽  
History Of ◽  
The Laptev Sea

Gas Distribution Features in the Upper Layer of Marine Sediments in the Continental Shelf of the Laptev Sea–Arctic Ocean Profile

Oceanology ◽  
2021 ◽  
Vol 61 (4) ◽  
pp. 472-487
Author(s):  
V. S. Sevastyanov ◽  
V. Yu. Fedulova ◽  
A. V. Stennikov ◽  
O. V. Kuznetsova ◽  
S. G. Naimushin ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Arctic Ocean ◽  
Marine Sediments ◽  
Laptev Sea ◽  
Gas Distribution ◽  
Distribution Features ◽  
The Laptev Sea

Mercury and methylmercury along a transect from the Lena river estuary across the Laptev Sea Shelf

2020 ◽  
Author(s):  
Van Liem Nguyen ◽  
Birgit Wild ◽  
Örjan Gustafsson ◽  
Igor Semiletov ◽  
Oleg Dudarev ◽  
...  
Keyword(s):  
Organic Matter ◽  
Continental Shelf ◽  
Arctic Ocean ◽  
River Delta ◽  
The Arctic ◽  
Laptev Sea ◽  
Terrestrial Organic Matter ◽  
Lena River ◽  
The Arctic Ocean ◽  
The Laptev Sea

<p>Widespread accelerated permafrost thawing is predicted for this century and beyond. This threatens to remobilize the large amounts of Mercury (Hg) currently ‘locked’ in Arctic permafrost soils to the Arctic Ocean and thus potentially lead to severe consequences for human and wildlife health. Future risks of Arctic Hg in a warmer climate are, however, poorly understood. One crucial knowledge gap to fill is the fate of Hg once it enters the marine environment on the continental shelves. Arctic rivers are already today suggested to be the main source of Hg into the Arctic Ocean, with dissolved and particulate organic matter (DOM and POM, respectively) identified as important vectors for the land to sea transport.</p><p>In this study, we have investigated total Hg (HgT) and monomethylmercury (MeHg) concentrations in surface sediments from the East Siberian Arctic Shelf (ESAS) along a transect from the Lena river delta to the Laptev Sea continental slope. The ESAS is the world’s largest continental shelf and receives large amounts of organic carbon by the great Arctic Russian rivers (e.g., Lena, Indigirka and Kolyma), remobilized from continuous and discontinuous permafrost regions in the river catchments, and from coastal erosion. Data on HgT and MeHg levels in ESAS sediments is however limited. Here, we observed concentrations of Hg ranging from 30 to 96 ng Hg g<sup>-1</sup> d.w. of HgT, and 0.03 to 9.5 ng Hg g<sup>-1</sup> d.w. of MeHg. Similar concentrations of HgT were observed close to the river delta (54 ± 19 ng Hg g<sup>-1</sup> d.w.), where >95 % of the organic matter is of terrestrial origin, and the other section of the transect (42 ± 7 ng Hg g<sup>-1</sup> d.w.) where the terrestrial organic matter is diluted with carbon from marine sources. In contrast, we observed higher concentrations of MeHg close to the river delta (0.72 ± 0.71 ng Hg g<sup>-1</sup> d.w. as MeHg) than further out on the continental shelf (0.031 ± 0.71 ng Hg g<sup>-1</sup> d.w. as MeHg). We also observed a positive correlation between the MeHg:Hg ratio and previously characterized molecular markers of terrestrial organic matter (Bröder et al. Biogeosciences (2016) & Nature Com. (2018)). We thus suggest riverine inputs, rather than in situ MeHg formation, to explain observed MeHg trends.</p>

Structure and geology of the continental shelf of the Laptev Sea, Eastern Russian Arctic

1998 ◽  
Vol 298 (4) ◽  
pp. 357-393 ◽  
Author(s):  
Sergei S Drachev ◽  
Leonid A Savostin ◽  
Victor G Groshev ◽  
Inna E Bruni
Keyword(s):  
Continental Shelf ◽  
Laptev Sea ◽  
Russian Arctic ◽  
The Laptev Sea

Holocene hydrographical changes of the eastern Laptev Sea (Siberian Arctic) recorded in δ18O profiles of bivalve shells

2004 ◽  
Vol 61 (1) ◽  
pp. 32-41 ◽  
Author(s):  
Thomas Mueller-Lupp ◽  
Henning A. Bauch ◽  
Helmut Erlenkeuser
Keyword(s):  
Oxygen Isotope ◽  
Sea Level ◽  
Bottom Water ◽  
River Mouth ◽  
Water Salinity ◽  
Laptev Sea ◽  
Modern Analogue ◽  
History Of ◽  
The Laptev Sea ◽  
Bivalve Shells

Oxygen isotope profiles along the growth axis of fossil bivalve shells of Macoma calcarea were established to reconstruct hydrographical changes in the eastern Laptev Sea since 8400 cal yr B.P. The variability of the oxygen isotopes (δ18O) in the individual records is mainly attributed to variations in the salinity of bottom waters in the Laptev Sea with a modern ratio of 0.50‰/salinity. The high-resolution δ18O profiles exhibit distinct and annual cycles from which the seasonal and annual salinity variations at the investigated site can be reconstructed. Based on the modern analogue approach oxygen isotope profiles of radiocarbon-dated bivalve shells from a sediment core located northeast of the Lena Delta provide seasonal and subdecadal insights into past hydrological conditions and their relation to the Holocene transgressional history of the Laptev Sea shelf. Under the assumption that the modern relationship between δ18Ow and salinity has been constant throughout the time, the δ18O of an 8400-cal-yr-old bivalves would suggest that bottom-water salinity was reduced and the temperature was slightly warmer, both suggesting a stronger mixture of riverine water to the bottom water. Reconstruction of the inundation history of the Laptev Sea shelf indicates local sea level ∼27 m below present at this time and a closer proximity of the site to the coastline and the Lena River mouth. Due to continuing sea level rise and a southward retreat of the river mouth, bottom-water salinity increased at 7200 cal yr B.P. along with an increase in seasonal variability. Conditions comparable to the modern hydrography were achieved by 3800 cal yr B.P.

Postglacial to Holocene history of the Laptev Sea continental margin: Palaeoenvironmental implications of benthic assemblages

2008 ◽  
Vol 183 (1) ◽  
pp. 40-60 ◽  
Author(s):  
Ekaterina Taldenkova ◽  
Henning A. Bauch ◽  
Anna Stepanova ◽  
Anna Strezh ◽  
Sergei Dem’yankov ◽  
...  
Keyword(s):  
Continental Margin ◽  
Laptev Sea ◽  
Benthic Assemblages ◽  
History Of ◽  
The Laptev Sea

scholarly journals Dynamics and History of the Laptev Sea and its Continental Hinterland: A Summary

1999 ◽  
pp. 695-711 ◽  
Author(s):  
J. Thiede ◽  
◽  
L. Timokhov ◽  
H. A. Bauch ◽  
D. Y. Bolshiyanov ◽  
...  
Keyword(s):  
Laptev Sea ◽  
History Of ◽  
The Laptev Sea

scholarly journals Composition of Sedimentary Organic Matter across the Laptev Sea Shelf: Evidences from Rock-Eval Parameters and Molecular Indicators

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3511
Author(s):  
Elena Gershelis ◽  
Andrey Grinko ◽  
Irina Oberemok ◽  
Elizaveta Klevantseva ◽  
Natalina Poltavskaya ◽  
...  
Keyword(s):  
Organic Matter ◽  
Surface Sediments ◽  
Continental Margins ◽  
Laptev Sea ◽  
Lena River ◽  
Nearshore Sediments ◽  
Rock Eval ◽  
Molecular Indicators ◽  
Sedimentation Regime ◽  
The Laptev Sea

Global warming in high latitudes causes destabilization of vulnerable permafrost deposits followed by massive thaw-release of organic carbon. Permafrost-derived carbon may be buried in the nearshore sediments, transported towards the deeper basins or degraded into the greenhouse gases, potentially initiating a positive feedback to climate change. In the present study, we aim to identify the sources, distribution and degradation state of organic matter (OM) stored in the surface sediments of the Laptev Sea (LS), which receives a large input of terrestrial carbon from both Lena River discharge and intense coastal erosion. We applied a suite of geochemical indicators including the Rock Eval parameters, traditionally used for the matured OM characterization, and terrestrial lipid biomarkers. In addition, we analyzed a comprehensive grain size data in order to assess hydrodynamic sedimentation regime across the LS shelf. Rock-Eval (RE) data characterize LS sedimentary OM with generally low hydrogen index (100–200 mg HC/g TOC) and oxygen index (200 and 300 CO2/g TOC) both increasing off to the continental slope. According to Tpeak values, there is a clear regional distinction between two groups (369–401 °C for the inner and mid shelf; 451–464 °C for the outer shelf). We suggest that permafrost-derived OM is traced across the shallow and mid depths with high Tpeak and slightly elevated HI values if compared to other Arctic continental margins. Molecular-based degradation indicators show a trend to more degraded terrestrial OC with increasing distance from the coast corroborating with RE results. However, we observed much less variation of the degradation markers down to the deeper sampling horizons, which supports the notion that the most active OM degradation in LS land-shelf system takes part during the cross-shelf transport, not while getting buried deeper.

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