8 research outputs found
Coastal dynamics at the Barents and Kara Sea key sites
No full textThe results of permafrost and coastal dynamics investigations at four key sites on the shores of the Kara and Barents Seas are discussed. Three ACD key sites, Marre-Sale, Shpindler, and Kolguev, characterize areas with active thermal erosion; key site Cape Bolvansky is found on a relatively stable coast. It is found that the coastal retreat rate has spatial and temporal variability, which is typical of the entire Arctic coast. Coastal deposits on the Kara and Barents Seas have a low organic carbon content. Annual input of material into the Kara Sea resulting from coastal degradation reaches 35–40 million t, including about 7.5 million t of ice, 0.35 million t of organic carbon, and 0.3 million t of soluble salts
Tabular ground ice origin: cryolithological and isotope-geochemical study
No full textAn integrated cryolithological-isotope-geochemical study was undertaken at five sites in the Arctic within the framework of a three-year INTAS project. The conclusion based on geochemical analyses is that at the Asian westernmost Yugorsky to the easternmost Chukotka, marine sedimentation changed to subaerial followed by permafrost and massive ice formation due to the regression of the polar basin. Burial of the surface ice was possible, mainly in the mountainous areas of the Arctic coasts, i.e. the Urals and Chukotka
METHANE IN GROUND ICE AND FROZEN SEDIMENTS IN THE COASTAL ZONE AND ON THE SHELF OF KARA SEA
Get PDFSummary Degradation of permafrost on the continental shelf and shores of the Arctic seas may be a main cause of the methane emission to the atmosphere from marine sediments. To quantify this effect it is necessary to have reliable data on the methane content in the underground ice and frozen Quaternary deposits. Samples of frozen (permafrost) sediments and ground ice, taken in three reference coastal sections made in the Mid- and Late Pleistocene coastal exposures and on the Kara sea shelf, were collected and studied. The samples were analyzed to determine composition, salinity, organic carbon content, and other characteristics of the underground ices. About 270 samples allowed determination of the gas composition and the methane concentration. The gas is present in the pores of the rocks and air bubbles in the ice. Gas was present in pores of sediments and in bubbles within the ice. It has been established that the composition of non-hydrocarbon gases in the underground ice does not correspond to the composition of the atmosphere in the time of formation of them. The methane content in the underground ice and frozen sediments is characterized by very high variability. The highest concentrations of methane are inherent in layers of the massive ground ice and reach up to 23000 ppm; the maximum concentration of methane in the massive vein ices does not exceed 900 ppm. High concentrations of methane in layers of the massive ice confirm their non-glacier formation. The highest, up to 6400 ppm, methane concentrations in permafrost sediments are characteristic for the Late Pleistocene marine clays, while in the Mid Pleistocene marine clays it does not exceed 1700 ppm. The isotopic composition of methane in frozen sediments and ground ice in both, the Cara Sea coast and shelf, is indicative of similar bacterial genesis of the gas. The total organic carbon content plays the limiting role in the methane production and its accumulation in the frozen sediments and ground ice
Геохимия природных вод и льдов Земли Норденшельда (о. Западный Шпицберген) [Geochemistry of natural water and ice objects on Nordenskiöld Land (Western Spitsbergen)] (in Russian)
No full textMethane and Dissolved Organic Matter in the Ground Ice Samples from Central Yamal: Implications to Biogeochemical Cycling and Greenhouse Gas Emission
No full textPermafrost thawing leads to mobilization of the vast carbon pool into modern biogeochemical cycling through the enhanced release of dissolved organic matter (DOM) and production of greenhouse gases (CO2 and CH4). In this work, we focus on the study of methane and DOM distribution and genesis in the ground ice samples of thermodenudational exposure in the Central Yamal (Russian Arctic). We propose that the liberation of the ice-trapped CH4 and generation of CO2 by DOM mineralization are the earliest factors of atmospheric greenhouse gases emission as a result of permafrost thawing. The observed enormously “light ” isotope signatures of methane (δ13C < −80‰, δD < −390‰) found in the tabular ground ice units significantly divergent in morphology and localization within the exposuremay be related to subzero (cryogenic) carbonate reduction a as significant factor of the local methane enrichment. DOM is mainly formed (>88%) by biochemically refractory humic acids. Distribution of the labile protein-like DOM reflects the specific features of carbon and nitrogen cycles in the tabular ground ice and ice wedge samples. Tabular ground ice units are shown to be a significant source of methane and high quality organic matter as well as dissolved inorganic nitrogen (DIN). Ice wedges express a high variation in DOM composition and lability
Geochimija prirodnych vod i ldov Zemli Nordenshelda (o. Zap. Shpitsbergen) (Geochemistry of natural water and ice objects on Nordenskiöld Land (Western Spitsbergen), in Russian)
No full textThe Batagay mega thaw slump, Yana Uplands, Yakutia, Russia: permafrost thaw dynamics on decadal time scale
No full textIce-rich permafrost that formed in glacial periods of the Quaternary is highly vulnerable to thaw under ongoing climate change and anthropogenic disturbance. Permafrost degradation processes such as thermokarst, thermo-denudation and thermo-erosion are actively shaping modern periglacial landscapes.
Retrogressive thaw slumps – also referred to as thermo-cirques – represent a highly dynamic geomorphologic feature in ice-rich permafrost regions. These rapidly forming landforms consist of a steep headwall surrounding a gently inclined slump floor where sediment erosion and accumulation takes place simulatenously and develop as a result of rapid permafrost thaw over several decades. Thaw slumps are commonly found in permafrost areas with near-surface, thick ground-ice layers that are susceptible to thermo-denudation and subsequent mass displacement through cryogenic landslides (Leibman et al., 2008). Thaw slumps are particularly frequent along riverbanks and coastlines in the Northwest American and West Siberian Arctic, where they are typically initiated by lateral erosion of the bluff toe. In these regions, buried glacier ice (massive ground ice) bodies or ice-rich glacial till have been mapped. Given their exceptional size of up to 40 ha in area and 25 m high headwalls, so-called mega slumps in northwestern Canada represent primary terrain destabilization features with different environmental settings than surrounding areas (Lantuit et al., 2012), but are a significant source for sediment and solute delivery to adjacent lakes and streams (Kokelj et al., 2013). However, in East Siberia, retrogressive thaw slumps have been described in the syngenetic Late Pleistocene Ice Complex (Yedoma) permafrost deposits, where massive ice wedges and segregated intrasedimentary ice results in total volumetric ice contents of up to 80-90%. Such retrogressive thaw slumps in syngenetic permafrost were investigated for example on the coastal area of the Dmitry Laptev Strait (Are et al., 2005). However, Yedoma deposits are also found on slopes of the Verkhoyan Mountain Range (Slagoda, 1991) and in valleys of surrounding foothills (Grosse et al., 2007) beyond the Yedoma main distributional range in the coastal lowlands of the Laptev and East Siberian seas.
The Batagay mega slump is at least two times larger than any previously described thaw slump, has been discovered near the village of Batagay, and has been the subject of some recent cryostratigraphical analysis (Kunitsky et al 2013). It exposes a profile of Yedoma deposits, reaching a thickness of 7 to 22 m in that area (Slagoda, 1991) and underlying ice-rich periglacial alluvial sand deposits of around 60 m thickness (Kunitsky et al., 2013). The observed rapid development of thermo-denudation at rates of up to 15 m per year, poses the question of whether the larger portions of the entire region between the Verkhoyan and Cherskiy mountain ranges may be more vulnerable to deep and rapid thaw following disturbances such as forest fires or forest clearance. Using a set of historical remote sensing data, Kunitsky et al. (2013) suggest that depression-like structures on the Kirgillyakh-Khatyngnakhskoy Mountain saddle begin in the early 1970s. The initial disturbance causing rapid thermo-denudational development of the Batagay mega thaw slump started at the end of the 1980s.
Here we present data from a remote sensing investigation of the mega slump (. in order to assess the planimetric dimensions and its recent expansion rates. We acquired very high resolution satellite imagery from QuickBird, IKONOS, KOMPSAT-2, WorldView-1 and WorldView-2, spanning a timeframe from 2006 to 2014. Aerotriangulation of the entire dataset was performed to ensure consistent co-registration between images. In addition, for terrain correction through ortho-rectification and for volumetric analyses of the entire mega slump, we derived an accurate digital elevation model (DEM) with 2m ground resolution from along and across track WorldView stereo imagery. The height difference between the headwall and the outflow of the slump into the Batagay river is 145 m along a distance of 2300m, while the slump maximum width is 800 m. Our analysis doesn’t show any signs of erosion slowdown along a headwall that is up to 86 m high. Comparison of the DEM with a reconstructed paleo-surface revealed that the slump has carved into the rolling topography to a depth of up to 73 m. The current size of the Batagay mega slump is >81 ha, while it had thawed >24.2 × 106 m³ of ice-rich permafrost through 2014. This huge amount of sediment released from the slump episodically dams up the Batagay river, forming a large temporary lake which then may discharge catastrophically. Geological on-site investigations and further geomorphometric analyses of this locality in conjunction with inter-annual and seasonal change detection observations will allow relating headwall retreat rates to local and regional controls on mega slump development and will help to identify potential areas susceptible to megaslump formation in non-glaciated regions.
References
Are, F.E., M.N. Grigoriev, H.-W. Hubberten, & V. Rachold (2005), Using thermoterrace dimensions to calculate the coastal erosion rate, Geo-Marine Letters, 25, 121-126.
Grosse, G., L. Schirrmeister, C. Siegert, V.V. Kunitsky, E.A. Slagoda, A.A. Andreev & A.Y. Dereviagyn (2007), Geological and geomorphological evolution of a sedimentary periglacial landscape in Northeast Siberia during the Late Quaternary, Geomorphology, 89(1-2), 25-51.
Kokelj, S.V., D. Lacelle, T.C. Lantz, J. Tunnicliffe, L. Malone, I.D. Clark & K.S. Chin (2013), Thawing of massive ground ice in mega slumps drives increases in stream sediment and solute flux across a range of watershed scales, Journal of Geophysical Research: Earth Surface, 118, 681-692.
Kunitsky, V.V., I.I. Syromyatnikov, L. Schirrmeister, Yu.B. Skachkov, G. Grosse, S. Wetterich, & M.N. Grigoriev (2013), Ice-rich permafrost and thermal denudation in the Batagay area - Yana Upland, East Siberia, Kriosfera Zemli (Earth' Cryosphere), 17(1), 56-68.
Lantuit, H., W.H. Pollard, N. Couture, M. Fritz, L. Schirrmeister, H. Meyer & H.-W. Hubberten (2012), Modern and Late Holocene Retrogressive Thaw Slump Activity on the Yukon Coastal Plain and Herschel Island, Yukon Territory, Canada, Permafrost and Periglacial Processes, 23(1), 39-51.
Leibman, M., A. Gubarkov, A. Khomutov, A. Kizyakov & B. Vanshtein (2008), Coastal processes at the tabular-ground-ice-bearing area, Yugorsky Peninsula, Russia, in: Kane, D.L. and Hinkel, K.M. (eds), Proceedings of the Ninth International Conference on Permafrost, University of Alaska Fairbanks, June 29-July 3 2008, 1037-1042.
Slagoda, E. A. (1991), Microstructure of permafrost slope deposits of the Kisilyakh Range, in: Melnikov, P.I. and Popov, A.I. (eds), Denudation in the cryolithozone, 19-29, Nauka, Moscow
МЕТАН В ПОДЗЕМНЫХ ЛЬДАХ И МЁРЗЛЫХ ОТЛОЖЕНИЯХ НА ПОБЕРЕЖЬЕ И ШЕЛЬФЕ КАРСКОГО МОРЯ
Get PDFSummary Degradation of permafrost on the continental shelf and shores of the Arctic seas may be a main cause of the methane emission to the atmosphere from marine sediments. To quantify this effect it is necessary to have reliable data on the methane content in the underground ice and frozen Quaternary deposits. Samples of frozen (permafrost) sediments and ground ice, taken in three reference coastal sections made in the Mid- and Late Pleistocene coastal exposures and on the Kara sea shelf, were collected and studied. The samples were analyzed to determine composition, salinity, organic carbon content, and other characteristics of the underground ices. About 270 samples allowed determination of the gas composition and the methane concentration. The gas is present in the pores of the rocks and air bubbles in the ice. Gas was present in pores of sediments and in bubbles within the ice. It has been established that the composition of non-hydrocarbon gases in the underground ice does not correspond to the composition of the atmosphere in the time of formation of them. The methane content in the underground ice and frozen sediments is characterized by very high variability. The highest concentrations of methane are inherent in layers of the massive ground ice and reach up to 23000 ppm; the maximum concentration of methane in the massive vein ices does not exceed 900 ppm. High concentrations of methane in layers of the massive ice confirm their non-glacier formation. The highest, up to 6400 ppm, methane concentrations in permafrost sediments are characteristic for the Late Pleistocene marine clays, while in the Mid Pleistocene marine clays it does not exceed 1700 ppm. The isotopic composition of methane in frozen sediments and ground ice in both, the Cara Sea coast and shelf, is indicative of similar bacterial genesis of the gas. The total organic carbon content plays the limiting role in the methane production and its accumulation in the frozen sediments and ground ice.В трёх береговых разрезах и в одной точке на шельфе Карского моря исследованы состав и свойства подземных льдов и мёрзлых отложений, включая газовый состав и концентрацию метана. Наиболее высокие концентрации метана (до 23 352 ppm) установлены в пластовых льдах, а в жильных льдах она достигает лишь 1112 ppm. Большие концентрации метана в воздушных пузырьках пластовых льдов и их изотопный состав указывают на не ледниковый генезис этих льдов
