| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
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| Initial Amendment Date: | June 27, 2012 |
| Latest Amendment Date: | June 27, 2012 |
| Award Number: | 1144176 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Paul Cutler
pcutler@nsf.gov (703)292-4961 OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | July 1, 2012 |
| End Date: | June 30, 2018 (Estimated) |
| Total Intended Award Amount: | $239,617.00 |
| Total Awarded Amount to Date: | $239,617.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1960 KENNY RD COLUMBUS OH US 43210-1016 (614)688-8735 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
Office of Sponsored Programs Columbus OH US 43210-1016 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | ANT Integrated System Science |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.078 |
ABSTRACT
Recent discoveries of widespread liquid water and microbial ecosystems below the Antarctic ice sheets have generated considerable interest in studying Antarctic subglacial environments. Understanding subglacial hydrology, the persistence of life in extended isolation and the evolution and stability of subglacial habitats requires an integrated, interdisciplinary approach. The collaborative project, Minimally Invasive Direct Glacial Exploration (MIDGE) of the Biogeochemistry, Hydrology and Glaciology of Blood Falls, McMurdo Dry Valleys will integrate geophysical measurements, molecular microbial ecology and geochemical analyses to explore a unique Antarctic subglacial system known as Blood Falls. Blood Falls is a hypersaline, subglacial brine that supports an active microbial community. The subglacial brine is released from a crevasse at the surface of the Taylor Glacier providing an accessible portal into an Antarctic subglacial ecosystem. Recent geochemical and molecular analyses support a marine source for the salts and microorganisms in Blood Falls. The last time marine waters inundated this part of the McMurdo Dry Valleys was during the Late Tertiary, which suggests the brine is ancient. Still, no direct samples have been collected from the subglacial source to Blood Falls and little is known about the origin of this brine or the amount of time it has been sealed below Taylor Glacier. Radar profiles collected near Blood Falls delineate a possible fault in the subglacial substrate that may help explain the localized and episodic nature of brine release. However it remains unclear what triggers the episodic release of brine exclusively at the Blood Falls crevasse or the extent to which the brine is altered as it makes its way to the surface.
The MIDGE project aims to determine the mechanism of brine release at Blood Falls, evaluate changes in the geochemistry and the microbial community within the englacial conduit and assess if Blood Falls waters have a distinct impact on the thermal and stress state of Taylor Glacier, one of the most studied polar glaciers in Antarctica. The geophysical study of the glaciological structure and mechanism of brine release will use GPR, GPS, and a small passive seismic network. Together with international collaborators, the 'Ice Mole' team from FH Aachen University of Applied Sciences, Germany (funded by the German Aerospace Center, DLR), MIDGE will develop and deploy innovative, minimally invasive technologies for clean access and brine sample retrieval from deep within the Blood Falls drainage system. These technologies will allow for the collection of samples of the brine away from the surface (up to tens of meters) for geochemical analyses and microbial structure-function experiments. There is concern over the contamination of pristine subglacial environments from chemical and biological materials inherent in the drilling process; and MIDGE will provide data on the efficacy of thermoelectric probes for clean access and retrieval of representative subglacial samples. Antarctic subglacial environments provide an excellent opportunity for researching survivability and adaptability of microbial life and are potential terrestrial analogues for life habitats on icy planetary bodies. The MIDGE project offers a portable, versatile, clean alternative to hot water and mechanical drilling and will enable the exploration of subglacial hydrology and ecosystem function while making significant progress towards developing technologies for minimally invasive and clean sampling of icy systems.
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PROJECT OUTCOMES REPORT
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This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
A diverse hydrologic system of liquid water exists beneath the ice sheets of Antarctica. These cold and dark aquatic environments are of interest to many scientific disciplines, including biologists studying the evolution of microbes isolated from the rest of Earth’s ecosystems and geologists studying underlying sediments for clues about how Antarctica’s climate has changed in the past. Despite the “extreme” conditions under the ice, these environments have been shown to harbor microbial life in the absence of sunlight or significant organic matter. Work on these subglacial waters can inform future exploration of subglacial extraterrestrial environments, including moons of Saturn and Jupiter (Enceladus, Europa) and the recently discovered liquid water beneath the South Polar Layered Deposits on Mars’ southern ice cap. Whether these sub-cryospheric “oceans” can sustain life today is a major question in astrobiology and planetary exploration.
Geophysical and satellite-based remote sensing investigations have demonstrated that Antarctic subglacial aquatic environments are diverse, including lakes ranging in size from over 10,000 km2 to less than 1 km2. These works have described lakes and ponds connected in series by subglacial streams, saturated sediments under flowing glacier ice, and even groundwater-type systems. All of these subglacial aquatic systems remain poorly understood due to the lack of direct sampling –– the logistical challenges associated with drilling through hundreds to thousands of meters of ice, without inadvertently contaminating the water, present a significant barrier. Because of this, there have only been few directly sampled subglacial waters, most recently along the Whillans Ice Stream in West Antarctica.
As part of an international collaborative effort, we sampled a hypersaline iron-rich brine within Taylor Glacier, Antarctica using clean entry techniques and a thermo-electric melting probe called the IceMole. Taylor glacier and the saturated sediments beneath it are the source of Blood Falls, a hypersaline, iron-rich subglacial flow that discharges at the terminus of Taylor Glacier in the western-most portion of Taylor Valley. This brine may also be hydrologically connected to sub-permafrost brine recently observed underlying Taylor Valley. While the discharge of Blood Falls has been sampled and described in detail, our work is the first to directly sample the source of Blood Falls. We encountered a brine within the glacier (englacial) at ~17 m deep within Taylor Glacier.
The geochemical/biogeochemical part of our overall work was designed to assess three questions: (1) What is the overall composition of the brine? (2) What is the original source of the solutes? And, (3) is the geochemistry of brine conducive to hosting life? We analyzed the brine waters for a large number of chemical and isotopic constituents. We found that the chemistry of the brine is dominated by sodium and chloride (Na-Cl) and it is more saline than Blood Falls. Although the brine is thought to be initially derived from the concentration of seawater, it also contains chemical constituents that are the result of rock weathering, implying that it has been in place for a significant amount of time. It is likely that the initial seawater is Miocene in age (over 5.3 million years old) and was introduced when Taylor Valley was connected to the ocean as a fjord. The work of our collaborators at the University of Tennessee, Knoxville have documented the microorganisms found in the brine. Our successful endeavor was the first to analyze hypersaline waters from an Antarctic subglacial/englacial environment.
Last Modified: 09/26/2018
Modified by: W. Berry Lyons
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