scholarly journals Thermokarst lakes formed in buried glacier ice: Observations from Bylot Island, eastern Canadian Arctic

2021 ◽  
Author(s):  
Stéphanie Coulombe ◽  
Daniel Fortier ◽  
Frédéric Bouchard ◽  
Michel Paquette ◽  
Denis Lacelle ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Arctic Lakes ◽  
Remotely Sensed Data ◽  
Thermokarst Lakes ◽  
Bathymetric Data ◽  
Thaw Consolidation ◽  
Bylot Island ◽  
Glacier Ice ◽  
Permafrost Regions ◽  
Area And Volume

Abstract. In formerly glaciated permafrost regions, extensive areas are still underlain by a considerable amount of glacier ice buried by glacigenic sediments. Although the extent and volume of undisturbed relict glacier ice are unknown, these ice bodies are predicted to melt with climate warming but their impact on landscape evolution remains poorly studied. The spatial distribution of buried glacier ice can play a significant role in reshaping periglacial landscapes, in particular thermokarst aquatic systems. This study focuses on lake initiation and development in response to the melting of buried glacier ice on Bylot Island, Nunavut. We studied a lake-rich area using lake-sediment cores, detailed bathymetric data, remotely sensed data and observations of buried glacier ice exposures. Our results suggest that initiation of deeper thermokarst lakes was triggered by the melting of buried glacier ice. They have subsequently enlarged through thermal and mechanical shoreline erosion, as well as vertically through thaw consolidation and subsidence, and they later coalesced with neighbouring water bodies to form larger lakes. Thus, these lakes now evolve as “classic” thermokarst lakes that expand in area and volume as a result of the melting of intrasedimental ground ice in the surrounding material and the underlying glaciofluvial and till material. It is expected that the deepening of thaw bulbs (taliks) and the enlargement of Arctic lakes in response to global warming will reach undisturbed buried glacier ice, if any, which in turn will substantially alter lake bathymetry, geochemistry and greenhouse gas emissions from Arctic lowlands.

scholarly journals Supplementary material to "Thermokarst lakes formed in buried glacier ice: Observations from Bylot Island, eastern Canadian Arctic"

2021 ◽  
Author(s):  
Stéphanie Coulombe ◽  
Daniel Fortier ◽  
Frédéric Bouchard ◽  
Michel Paquette ◽  
Denis Lacelle ◽  
...  
Keyword(s):  
Canadian Arctic ◽  
Thermokarst Lakes ◽  
Bylot Island ◽  
Glacier Ice ◽  
Supplementary Material ◽  
Eastern Canadian Arctic

scholarly journals Origin, burial and preservation of late Pleistocene-age glacier ice in Arctic permafrost (Bylot Island, NU, Canada)

2018 ◽  
Author(s):  
Stephanie Coulombe ◽  
Daniel Fortier ◽  
Denis Lacelle ◽  
Mikhail Kanevskiy ◽  
Yuri Shur
Keyword(s):  
Late Pleistocene ◽  
Aquatic Ecosystems ◽  
Ice Sheets ◽  
Ground Surface ◽  
The Arctic ◽  
The Past ◽  
Geochemical Properties ◽  
Bylot Island ◽  
Glacier Ice ◽  
Permafrost Regions

Abstract. Over the past decades, observations of buried glacier ice exposed in coastal bluffs and headwalls of retrogressive thaw slumps of the Arctic indicate that considerable amounts of Pleistocene glacier ice survived the deglaciation and are still preserved in permafrost. In exposures, relict glacier ice and intrasedimental ice often coexist and look alike but their genesis is strikingly different. Identifying the origin of ground ice is required to model its spatial distribution and abundance, which is necessary to model the response of circumpolar permafrost regions to climate change. This paper aims to present a detailed description and report physical and geochemical properties of glacier ice buried in the permafrost of Bylot Island (Nunavut) as well as identify geomorphic processes that led to the burial and preservation of the ice. The massive ice exposure and core samples were described according to the cryostratigraphic approach, combining the analysis of permafrost cryofacies and cryostructures, ice crystallography, stable O-H isotopes and cation contents. The buried glacier ice consisted of clear to whitish englacial ice having large crystals (cm) and small gas inclusions (mm) at crystal intersections, similar to observations of englacial ice facies commonly found on contemporary glaciers and ice sheets. However, the isotopic composition of the buried ice differed markedly from contemporary glacier ice and indicated the late Pleistocene age of the ice. This ice predates the aggradation of the permafrost and can be used as an archive to infer paleo-environmental conditions at the study site. As most of the arctic landscapes are still strongly determined by its glacial legacy, the melting of these large ice bodies could lead to extensive slope failures and settlement of the ground surface, with significant impact on permafrost geosystem landscape dynamics, terrestrial and aquatic ecosystems, and infrastructure.

scholarly journals Processes controlling the downstream evolution of ice rheology in glacier shear margins: case study on Rutford Ice Stream, West Antarctica

2018 ◽  
Vol 64 (246) ◽  
pp. 583-594 ◽  
Author(s):  
BRENT M. MINCHEW ◽  
COLIN R. MEYER ◽  
ALEXANDER A. ROBEL ◽  
G. HILMAR GUDMUNDSSON ◽  
MARK SIMONS
Keyword(s):  
Physical Models ◽  
West Antarctica ◽  
Remotely Sensed Data ◽  
Softening Effect ◽  
Outlet Glacier ◽  
Ice Stream ◽  
Glacier Ice ◽  
Local Shear ◽  
Shear Heating ◽  
The Impact

ABSTRACTIce rheology governs how glaciers flow and respond to environmental change. The rheology of glacier ice evolves in response to a variety of mechanisms, including damage, heating, melting and the development of crystalline fabric. The relative contributions of these rheological mechanisms are not well understood. Using remotely sensed data and physical models, we decouple the influence of each of the aforementioned mechanisms along the margins of Rutford Ice Stream, a laterally confined outlet glacier in West Antarctica. We show that fabric is an important control on ice rheology in the shear margins, with an inferred softening effect consistent with a single-maximum fabric. Fabric evolves to steady state near the onset of streaming flow, and ice progressively softens downstream almost exclusively due to shear heating. The rate of heating is sensitive to local shear strain rates, which respond to local changes in bed topography as ice is squeezed through the basal trough. The impact of shear heating on the downstream evolution of ice rheology in a laterally confined glacier suggests that the thermoviscous feedback – wherein faster ice flow leads to higher rates of shear heating, further softening the ice – is a fundamental control on glacier dynamics.

scholarly journals Glacier area and volume changes of Hidden Valley, Mustang, Nepal from ~1980s to 2010 based on remote sensing

2015 ◽  
Vol 368 ◽  
pp. 57-62 ◽  
Author(s):  
L. Lama ◽  
R. B. Kayastha ◽  
S. B. Maharjan ◽  
S. R. Bajracharya ◽  
M. B. Chand ◽  
...  
Keyword(s):  
Automatic Method ◽  
Glacier Area ◽  
Landsat Images ◽  
Change Analysis ◽  
Manual Delineation ◽  
Object Based ◽  
Hidden Valley ◽  
The Status ◽  
Glacier Ice ◽  
Area And Volume

Abstract. Glaciers are one of the important natural resources of freshwater and sources of water for hydropower, agriculture and drinking whenever the water is scarce. This mapping and change analysis helps to understand the status and decadal changes of glaciers in Hidden Valley, Mustang district, Nepal. The investigation is carried out using Landsat images of the years 1977 (~1980s), 1990, 2000 and 2010. We mapped 10 glaciers of the Hidden Valley covering an area of 19.79 km2 based on the object-based image classification method using an automatic method and manual delineation by a Geographic Information System (GIS), separately. The glacier outlines for 2010, 2000, 1990 and 1980s in both methods are delineated from the multispectral Landsat images of the respective years. The total area losses of the glaciers from the automatic method are 1.713 and 0.625 km2 between 1990−2000 and 2000−2010 and from manual delineation are 2.021, 1.264, 1.041 km2 between ~1980s−1990, 1990−2000 and 2000−2010. The amount of average estimated glacier ice reserves lost is 0.326 km3 (26.26 %) and the total glacier area loss is 4.33 km2 (21.87 %) from the 1980s to 2010 based on manual delineation. The glaciers of Hidden Valley are shrinking and fragmented due to decrease in glacier area and ice reserves.

Chronology and late-Holocene evolution of Caleta de los Loros, NE Patagonia, Argentina

The Holocene ◽  
2018 ◽  
Vol 28 (8) ◽  
pp. 1276-1287 ◽  
Author(s):  
Lasse Sander ◽  
Morten Pejrup ◽  
Andrew Sean Murray ◽  
Gerardo ME Perillo ◽  
Luís Ariél Raniolo ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Sediment Cores ◽  
Spatial Arrangement ◽  
Remotely Sensed Data ◽  
Sediment Delivery ◽  
Sedimentary Records ◽  
Term Change ◽  
Northern Shore ◽  
Coastal Deposits ◽  
Sand And Gravel

Geomorphological and sedimentary records of Holocene coastal deposits may serve as archives for the local reconstruction of trends in coastal evolution and of the key forcing parameters controlling long-term change. We here present new observations on the sedimentology, chronology, and surface properties of a coupled beach ridge and coastal lagoon system located on the northern shore of San Matías Gulf, NE Patagonia, Argentina. The study is based on remotely sensed data, sediment cores, and a large number of samples dated using optically stimulated luminescence (OSL). The field site is located in a topographical depression within a cliffed shoreline composed of friable sand and gravel stones. The oldest preserved lagoonal deposits formed in the protected inner part of the system c. 2300 years ago. An up to 4-km-wide strandplain prograded rapidly between c. 1000 and 500 years in the more exposed western part of the system. Lagoonal deposition occurred primarily during the last 500 years. The chronology and spatial arrangement of landforms appear to result from a switch-over in sediment delivery probably caused by local implications of major shifts in climate regime. Even though we were not able to identify or benchmark the precise triggers of geomorphological change at Caleta de los Loros, our study presents an example of the potential importance of environmental changes on the rapid and non-linear development of coastal sedimentary systems.

Characterization of perfluoroalkyl substances in sediment cores from High and Low Arctic lakes in Canada

2019 ◽  
Vol 666 ◽  
pp. 414-422 ◽  
Author(s):  
John J. MacInnis ◽  
Igor Lehnherr ◽  
Derek C.G. Muir ◽  
Roberto Quinlan ◽  
Amila O. De Silva
Keyword(s):  
Sediment Cores ◽  
Arctic Lakes ◽  
Perfluoroalkyl Substances ◽  
Low Arctic

scholarly journals Cirques of the Presidential Range, New Hampshire, and surrounding alpine areas in the northeastern United States

2002 ◽  
Vol 53 (1) ◽  
pp. 25-45 ◽  
Author(s):  
P. Thompson Davis
Keyword(s):  
United States ◽  
New York ◽  
New Hampshire ◽  
Sediment Cores ◽  
Adirondack Mountains ◽  
Catskill Mountains ◽  
Northeastern United States ◽  
Radiocarbon Age ◽  
Glacier Ice ◽  
Low Altitude

Abstract Evidence for rejuvenation of cirque glaciers following wastage of continental ice remains elusive for the Presidential Range and Mount Moosilauke of New Hampshire, Mount Katahdin and the Longfellow Mountains of Maine, and the Adirondack Mountains of New York. At Ritterbush Pond in the northern Green Mountains of Vermont, radiocarbon ages from lake sediment cores suggest that a low-altitude valley head, located up- valley of a series of cross-valley moraines, was ice-free by 11,940 14 C yrs BP (Bierman et al. , 1997). Although some workers argue that these moraines in Vermont are evidence for cirque glaciation, the moraines could have been formed by a tongue of continental ice during deglaciation. At Johnson Hollow Brook valley in the Catskill Mountains of New York, a radiocarbon age from basal sediments in a pond dammed by a moraine suggests that glacier ice may have persisted until 10,860 14 C yrs BP (Lederer and Rodbell, 1998). Because this moraine appears to have been deposited by a cirque glacier, the radiocarbon age provides the best evidence in the northeastern United States for cirque glaciation post-dating recession of continental ice. Cirque morphometric data, compiled from newly available topographic maps, add to the conundrum that these two sites in the Green and Catskill Mountains should not be nearly as favorable for maintaining local glaciers post- dating icesheet recession as higher-altitude and better-developed cirques in the Presidential Range and Mount Katahdin, where evidence for post-icesheet cirque glaciers is lacking.

scholarly journals BATHYMETRIC AND GEOLOGICAL PROPERTIES OF THE ADRIATIC SEA

2021 ◽  
Vol 36 (2) ◽  
pp. 93-107
Author(s):  
Ljerka Vrdoljak ◽  
Mate Režić ◽  
Ivan Petričević
Keyword(s):  
Adriatic Sea ◽  
Morphological Variability ◽  
Geological Data ◽  
Shallow Sea ◽  
Volume Calculation ◽  
Digital Maps ◽  
Bathymetric Data ◽  
Source Data ◽  
Analyse Data ◽  
Area And Volume

Advance in the visualization of the bathymetric and geological data from charted to digital maps and models opened the possibility to analyse data within Geographic Information System (GIS) functionalities. In this paper, bathymetric and geological properties of the Adriatic Sea were analysed using the General Bathymetric Chart of the Ocean (GEBCO) 2020 digital bathymetric model (DBM) and data from the European Marine Observation and Data Network (EMODnet). The bathymetric analysis includes depth statistics, area and volume calculation, hypsometry, and analysis of the heterogeneity of bathymetric data from the GEBCO 2020 DBM within the limits of the Adriatic defined by the International Hydrographic Organization (IHO) and 3 sub-basins delineated according to the bathymetry. The geological analysis includes seabed substrate map from EMODnet data and kilometre-scale seabed variability in the Adriatic. The GEBCO 2020 DBM shows that the Adriatic Sea is a shallow sea with a mean depth of -253 metres and over 50% of area shallower than 100 metres. The area of the Adriatic Sea is 138 516 km2 with a total volume of 35 521 km3. Patterns describing morphological variability coincide with the heterogeneity of the underlying source data of the GEBCO 2020 digital bathymetry model and major structures in the Adriatic Sea.

scholarly journals An availibility of arctic lakes organic sediments to microbial degradation: a laboratory incubation experiment

2021 ◽  
Vol 67 (1) ◽  
pp. 100-121
Author(s):  
N. K. Alekseeva ◽  
S. Yu. Evgrafova ◽  
A. E. Detsura ◽  
A. V. Guzeva ◽  
M. K. Meteleva ◽  
...  
Keyword(s):  
High Temperatures ◽  
Methane Emission ◽  
Temperature Increase ◽  
Climatic Changes ◽  
Arctic Lakes ◽  
Permafrost Zone ◽  
The Arctic ◽  
Biogeochemical Processes ◽  
Oxbow Lakes ◽  
Thermokarst Lakes

The water ecosystems of the Arctic region are most vulnerable to modern climatic changes since the global biogeochemical processes mostly occur on the territories of the permafrost zone. Aquatic ecosystems show a high degree of sensitivity to climatic changes; both in these and in other ecosystems, the biogeochemical processes are intense. These water bodies are located in the permafrost zone, which is vulnerable to temperature increases. The paper gives new insights into the fundamental research question of how fast the organic matter of thawing permafrost can be converted to greenhouse gases emitted into the atmosphere (CO2, CH4). We aimed to assess the microbial response and the associated release of CO2 and CH4 from the Arctic lakes in response to temperature increase. We investigated lakes located in the Lena River delta in the Samoylov Island, Russia, at 72° 22′ N, 126° 28′ E. Bottom sediments from three thermokarst and three oxbow lakes were anaerobically incubated in the laboratory at two temperature regimes (at 4 °C and at 25 °C). All the oxbow lakes have shown similar dynamics of methane emission both at low temperatures (4 °C) and at high temperatures (25 °C). The shift of carbon isotopic composition in methane has indicated that methane is emitted in all the oxbow lakes with a similar composition of microbial communities. In the thermokarst lakes, the emission of methane in the sediments proceeded differently at low and at high temperatures. These results have indicated a dissimilar composition of methanogenic / methanotrophic populations in the thermokarst and oxbow lakes. In both cases, the temperature increase caused a growth in methane emission from the sediments of the Arctic lakes. The thermokarst lakes will make a greater contribution to methane emission than the oxbow lakes. Thus, it is believed that the emission of methane from the thermokarst lakes will rise from 6 to 46 times due to ambient temperature increase. Methane emission from the oxbow lakes will grow from 1.8 to 7.6 times. Our results suggest that with the global warming both thermokarst and oxbow lakes could become a great source of methane emission into the atmosphere.

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