scholarly journals Basal melting over Subglacial Lake Ellsworth and its catchment: insights from englacial layering

2020 ◽  
Vol 61 (81) ◽  
pp. 198-205
Author(s):  
Neil Ross ◽  
Martin Siegert
Keyword(s):  
High Resolution ◽  
West Antarctica ◽  
Microbial Life ◽  
Lake Vostok ◽  
Subglacial Lake ◽  
Lake Outlet ◽  
Hydrological System ◽  
Subglacial Lakes ◽  
Basal Melting ◽  
Insight Into

AbstractDeep-water ‘stable’ subglacial lakes likely contain microbial life adapted in isolation to extreme environmental conditions. How water is supplied into a subglacial lake, and how water outflows, is important for understanding these conditions. Isochronal radio-echo layers have been used to infer where melting occurs above Lake Vostok and Lake Concordia in East Antarctica but have not been used more widely. We examine englacial layers above and around Lake Ellsworth, West Antarctica, to establish where the ice sheet is ‘drawn down’ towards the bed and, thus, experiences melting. Layer drawdown is focused over and around the northwest parts of the lake as ice, flowing obliquely to the lake axis becomes afloat. Drawdown can be explained by a combination of basal melting and the Weertman effect, at the transition from grounded to floating ice. We evaluate the importance of these processes on englacial layering over Lake Ellsworth and discuss implications for water circulation and sediment deposition. We report evidence of a second subglacial lake near the head of the hydrological catchment and present a new high-resolution bed DEM and hydropotential model of the lake outlet zone. These observations provide insight into the connectivity between Lake Ellsworth and the wider subglacial hydrological system.

scholarly journals Basal melting over Subglacial Lake Ellsworth and its catchment: insights from englacial layering

2020 ◽  
Author(s):  
Neil Ross ◽  
Martin Siegert
Keyword(s):  
High Resolution ◽  
West Antarctica ◽  
Microbial Life ◽  
Lake Vostok ◽  
Subglacial Lake ◽  
Lake Outlet ◽  
Hydrological System ◽  
Subglacial Lakes ◽  
Basal Melting ◽  
Insight Into

<p>Deep-water ‘stable’ subglacial lakes likely contain microbial life adapted in isolation to extreme environmental conditions. How water is supplied into a subglacial lake, and how water outflows, is important for understanding these conditions. Isochronal radio-echo layers have been used to infer where melting occurs above Lake Vostok and Lake Concordia in East Antarctica but have not been used more widely. We examine englacial layers above and around Lake Ellsworth, West Antarctica, to establish where the ice sheet is ‘drawn down’ towards the bed and, thus, experiences melting. Layer drawdown is focused over and around the NW parts of the lake as ice, flowing obliquely to the lake axis, becomes afloat. Drawdown can be explained by a combination of basal melting and the Weertman effect, at the transition from grounded to floating ice. We evaluate the importance of these processes on englacial layering over Lake Ellsworth and discuss implications for water circulation and sediment deposition. We report evidence of a second subglacial lake near the head of the hydrological catchment and present a new high-resolution bed DEM and hydropotential model of the lake outlet zone. These observations provide insight into the connectivity between Lake Ellsworth and the wider subglacial hydrological system.</p>

scholarly journals Antarctic subglacial lake exploration: first results and future plans

2016 ◽  
Vol 374 (2059) ◽  
pp. 20140466 ◽  
Author(s):  
Martin J. Siegert ◽  
John C. Priscu ◽  
Irina A. Alekhina ◽  
Jemma L. Wadham ◽  
W. Berry Lyons
Keyword(s):  
Lake Water ◽  
Ice Core ◽  
Hot Water ◽  
Microbial Life ◽  
Lake Vostok ◽  
Subglacial Lake ◽  
Coastal Margin ◽  
First Results ◽  
Scientific Results ◽  
Subglacial Lakes

After more than a decade of planning, three attempts were made in 2012–2013 to access, measure in situ properties and directly sample subglacial Antarctic lake environments. First, Russian scientists drilled into the top of Lake Vostok, allowing lake water to infiltrate, and freeze within, the lower part of the ice-core borehole, from which further coring would recover a frozen sample of surface lake water. Second, UK engineers tried unsuccessfully to deploy a clean-access hot-water drill, to sample the water column and sediments of subglacial Lake Ellsworth. Third, a US mission successfully drilled cleanly into subglacial Lake Whillans, a shallow hydraulically active lake at the coastal margin of West Antarctica, obtaining samples that would later be used to prove the existence of microbial life and active biogeochemical cycling beneath the ice sheet. This article summarizes the results of these programmes in terms of the scientific results obtained, the operational knowledge gained and the engineering challenges revealed, to collate what is known about Antarctic subglacial environments and how to explore them in future. While results from Lake Whillans testify to subglacial lakes as being viable biological habitats, the engineering challenges to explore deeper more isolated lakes where unique microorganisms and climate records may be found, as exemplified in the Lake Ellsworth and Vostok missions, are considerable. Through international cooperation, and by using equipment and knowledge of the existing subglacial lake exploration programmes, it is possible that such environments could be explored thoroughly, and at numerous sites, in the near future.

scholarly journals Prospects for metazoan life in sub-glacial Antarctic lakes: the most extreme life on Earth?

2019 ◽  
Vol 18 (05) ◽  
pp. 416-419 ◽  
Author(s):  
Sven Thatje ◽  
Alastair Brown ◽  
Claus-Dieter Hillenbrand
Keyword(s):  
Hydrothermal Vents ◽  
Pure Water ◽  
Hydrothermal Activity ◽  
Microbial Life ◽  
Lake Vostok ◽  
Physico Chemical ◽  
Physiological Adaptations ◽  
Subglacial Lakes ◽  
Life On Earth ◽  
Harsh Conditions

AbstractAbout 400 subglacial lakes are known from Antarctica. The question of whether life unique of subglacial lakes exists has been paramount since their discovery. Despite frequent evidence of microbial life mostly from accretion ice, subglacial lakes are characterized by physiologically hostile conditions to metazoan life, as we know it. Pure water (salinity ≤0.4–1.2%), extreme cold (−3°C), high hydrostatic pressure, areas of limited or no oxygen availability and permanent darkness altogether require physiological adaptations to these harsh conditions. The record of gene sequences including some associated with hydrothermal vents does foster the idea of metazoan life in Lake Vostok. Here, we synthesize the physico-chemical environment surrounding sub-glacial lakes and potential sites of hydrothermal activity and advocate that the physico-chemical stability found at these sites may be the most likely sites for metazoan life to exist. The unique conditions presented by Lake Vostok may also offer an outlook on life to be expected in extra-terrestrial subglacial environments, such as on Jupiter's moon Europa or Saturn's moon Enceladus.

Detecting active subglacial lakes beneath the Greenland Ice Sheet using ArcticDEM

2020 ◽  
Author(s):  
Jade Bowling ◽  
Amber Leeson ◽  
Malcolm McMillan ◽  
Stephen Livingstone ◽  
Andrew Sole
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Elevation ◽  
Surface Model ◽  
Ice Dynamics ◽  
Subglacial Lake ◽  
Flow Speeds ◽  
Elevation Data ◽  
Hydrological System ◽  
Subglacial Lakes

<p>A total of 63 subglacial lakes have been documented beneath the Greenland Ice Sheet using a combination of radio-echo sounding and surface elevation change measurements. Of these, only 7 lakes have shown evidence of hydrological activity over the period 2001-2018. Draining lakes have been observed to drive transient changes in local ice flow speeds in Antarctica. The sudden discharge of water during a subglacial lake outburst event causes the subglacial lake roof to subside, which propagates to the surface, resulting in the formation of collapse basins (typically ~50-70 m in depth). These surface features can be detected using remote sensing techniques.</p><p>Whilst over 100 active subglacial lakes have been identified in Antarctica, predominantly beneath ice streams, little is known about the extent, volume of water stored and residence times of active subglacial lakes in Greenland, together with any potential influence of drainage events on local ice dynamics and sediment evacuation rates. Here, we explore the potential of the high resolution ArcticDEM stereogrammetric digital surface model (DSM) open source dataset, generated from satellite optical imagery, to identify and monitor subglacial lake-derived collapse basins. The ArcticDEM provides 2 m time-stamped surface elevation data, covering ~160 million km<sup>2</sup>, offering an exciting opportunity to map elevation changes between 2009-2017. This study presents the first effort to utilise ArcticDEM data at an ice-sheet scale to identify and monitor active subglacial lakes beneath the Greenland Ice Sheet, which we hope will ultimately improve our understanding of its complex subglacial hydrological system.</p>

scholarly journals Brief communication: Heterogenous thinning and subglacial lake activity on Thwaites Glacier, West Antarctica

2020 ◽  
Vol 14 (12) ◽  
pp. 4603-4609
Author(s):  
Andrew O. Hoffman ◽  
Knut Christianson ◽  
Daniel Shapero ◽  
Benjamin E. Smith ◽  
Ian Joughin
Keyword(s):  
Time Series ◽  
Austral Winter ◽  
West Antarctica ◽  
Subglacial Lake ◽  
Satellite Velocity ◽  
Ice Velocity ◽  
Subglacial Lakes ◽  
Speed Fluctuations ◽  
Lake Systems

Abstract. A system of subglacial lakes drained on Thwaites Glacier from 2012–2014. To improve coverage for subsequent drainage events, we extended the elevation and ice-velocity time series on Thwaites Glacier through austral winter 2019. These new observations document a second drainage cycle in 2017/18 and identified two new lake systems located in the western tributaries of Thwaites and Haynes glaciers. In situ and satellite velocity observations show temporary < 3 % speed fluctuations associated with lake drainages. In agreement with previous studies, these observations suggest that active subglacial hydrology has little influence on thinning and retreat of Thwaites Glacier on decadal to centennial timescales.

scholarly journals Dynamic flows create potentially habitable conditions in Antarctic subglacial lakes

2021 ◽  
Vol 7 (8) ◽  
pp. eabc3972
Author(s):  
Louis-Alexandre Couston ◽  
Martin Siegert
Keyword(s):  
Bulk Water ◽  
Water Sampling ◽  
Stable Layer ◽  
Microbial Life ◽  
Subglacial Lake ◽  
Physical Conditions ◽  
Dynamic Flows ◽  
Subglacial Lakes ◽  
Ice Water ◽  
The Antarctic

Trapped beneath the Antarctic ice sheet lie over 400 subglacial lakes, which are considered to be extreme, isolated, yet viable habitats for microbial life. The physical conditions within subglacial lakes are critical to evaluating how and where life may best exist. Here, we propose that Earth’s geothermal flux provides efficient stirring of Antarctic subglacial lake water. We demonstrate that most lakes are in a regime of vigorous turbulent vertical convection, enabling suspension of spherical particulates with diameters up to 36 micrometers. Thus, dynamic conditions support efficient mixing of nutrient- and oxygen-enriched meltwater derived from the overlying ice, which is essential for biome support within the water column. We caution that accreted ice analysis cannot always be used as a proxy for water sampling of lakes beneath a thin (<3.166 kilometers) ice cover, because a stable layer isolates the well-mixed bulk water from the ice-water interface where freezing may occur.

A large tectonic-controlled subglacial lake with ocean drainage in Princess Elizabeth Land, East Antarctica

2021 ◽  
Author(s):  
Shuai Yan ◽  
Donald D. Blankenship ◽  
Duncan A. Young ◽  
Jamin S. Greenbaum ◽  
Lin Li ◽  
...  
Keyword(s):  
Satellite Image ◽  
Image Data ◽  
Melting Rate ◽  
Water Volume ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Subglacial Lake ◽  
Sediment Volume ◽  
Subglacial Lakes ◽  
Basal Melting

&lt;p&gt;The Princess Elizabeth Land (PEL) sector of the East Antarctic Ice Sheet, one of the largest grounded ice reservoirs in Antarctica, is adjacent to regions that experienced significant change during the last glacial maximum. The identification of subglacial water in PEL (to date only inferred from satellite image data) would provide important constraints on our estimation of the basal thermal condition in this region. Also, the existence of a large subglacial hydrology system in PEL comes with potential impacts on the basal melting rate and stability of downstream ice shelves, such as the West Ice Shelf. Here we present geophysical evidences confirming the existence of a large subglacial lake in PEL, hereby referred as Lake Snow Eagle (LSE), for the first time, using recently acquired aerogeophyscial data by international collaborations. We estimate LSE to be about 42 km in length and 370 km&lt;sup&gt;2&lt;/sup&gt; in area, making it one of the largest subglacial lakes in Antarctica. LSE is shown to lie in a subglacial canyon system that is linked to the coastal ice shelves, which makes LSE the first known major Antarctic interior water body that has a potential direct hydrological pathway into the ocean. We then systematically investigate its geological characteristics and bathymetry by 2-D geophysics modellings. We estimate the water volume of LSE to be about 21 km&lt;sup&gt;3&lt;/sup&gt;, while the sediment volume to be about 20 km&lt;sup&gt;3&lt;/sup&gt;. Our geophysical modelling results also suggest that LSE is located along a compressional geologic boundary, indicating possible tectonic controls over LSE.&lt;/p&gt;

scholarly journals Microbiology of the subglacial Lake Vostok: first results of borehole-frozen lake water analysis and prospects for searching for lake inhabitants

2016 ◽  
Vol 374 (2059) ◽  
pp. 20140292 ◽  
Author(s):  
Sergey A. Bulat
Keyword(s):  
Lake Water ◽  
Water Samples ◽  
Point Of View ◽  
Microbial Life ◽  
Lake Vostok ◽  
Subglacial Lake ◽  
Comparison Results ◽  
First Results ◽  
Accretion Ice ◽  
First Time

This article examines the question of the possible existence of microbial life inhabiting the subglacial Lake Vostok buried beneath a 4 km thick Antarctic ice sheet. It represents the results of analysis of the only available frozen lake water samples obtained upon the first lake entry and subsequent re-coring the water frozen within the borehole. For comparison, results obtained by earlier molecular microbiological studies of accretion ice are included in this study, with the focus on thermophiles and an unknown bacterial phylotype. A description of two Lake Vostok penetrations is presented for the first time from the point of view of possible clean water sampling. Finally, the results of current studies of Lake Vostok frozen water samples are presented, with the focus on the discovery of another unknown bacterial phylotype w123-10 distantly related to the above-mentioned unknown phylotype AF532061 detected in Vostok accretion ice, both successfully passing all possible controls for contamination. The use of clean-room facilities and the establishment of a contaminant library are considered to be prerequisites for research on microorganisms from Lake Vostok. It seems that not yet recorded microbial life could exist within the Lake Vostok water body. In conclusion, the prospects for searching for lake inhabitants are expressed with the intention to sample the lake water as cleanly as possible in order to make sure that further results will be robust.

scholarly journals Potential technological solution for sampling the bottom sediments of the subglacial lake Vostok: relevance and formulation of investigation goals

2021 ◽  
Vol 252 ◽  
pp. 779-787
Author(s):  
Aleksey Bolshunov ◽  
Nikolay Vasiliev ◽  
Igor Timofeev ◽  
Sergey Ignatiev ◽  
Dmitriy Vasiliev ◽  
...  
Keyword(s):  
Environmental Safety ◽  
Climatic Conditions ◽  
Natural Phenomenon ◽  
Bottom Surface ◽  
Large Area ◽  
Lake Vostok ◽  
Subglacial Lake ◽  
Vostok Station ◽  
Environmentally Safe ◽  
Subglacial Lakes

The subglacial Lake Vostok in Antarctic is a unique natural phenomenon, its comprehensive study involves sampling of water and bottom surface rocks. For further study of the lake, it is necessary to drill a new access well and develop environmentally safe technologies for its exploration. This article discusses existing and potential technologies for sampling bottom surface rocks of subglacial lakes. All these technologies meet environmental safety requirements and are conducive for sampling. The authors have proposed an alternative technology, using a walking device, which, due to its mobility, enables selective sampling of rocks across a large area from a single access well. The principal issues, related to the implementation of the proposed technology, are investigated within this article. This report is prepared by a team of specialists with many years of experience in drilling at the Vostok Station in Antarctic and in experimental work on the design of equipment and non-standard means of mechanization for complicated mining, geological and climatic conditions.

scholarly journals Connected subglacial lake activity on lower Mercer and Whillans Ice Streams, West Antarctica, 2003–2008

2009 ◽  
Vol 55 (190) ◽  
pp. 303-315 ◽  
Author(s):  
Helen Amanda Fricker ◽  
Ted Scambos
Keyword(s):  
Water Movement ◽  
Quantitative Information ◽  
West Antarctica ◽  
Ice Streams ◽  
Image Differencing ◽  
Subglacial Lake ◽  
Modis Image ◽  
Hydrologic System ◽  
Image Pairs ◽  
Subglacial Lakes

AbstractWe examine patterns of localized surface elevation change in lower Mercer and Whillans Ice Streams, West Antarctica, which we interpret as subglacial water movement through a system of lakes and channels. We detect and measure the lake activity using repeat-track laser altimetry from ICESat and image differencing from MODIS image pairs. A hydrostatic-potential map for the region shows that the lakes are distributed across three distinct hydrologic regimes. Our analysis shows that, within these regimes, some of the subglacial lakes appear to be linked, with drainage events in one reservoir causing filling and follow-on drainage in adjacent lakes. We also observe changes near ice raft ‘a’ in lower Whillans Ice Stream, and interpret them as evidence of subglacial water and other changes at the bed. The study provides quantitative information about the properties of this complex subglacial hydrologic system, and a relatively unstudied component of ice-sheet mass balance: subglacial drainage across the grounding line.

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