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Chapman Conference on the Exploration and Study of Antarctic Subglacial AquaticEnvironments (SAE)

Baltimore, Maryland USA15–17 March 2010

Conveners• Martin J. Siegert, University of Edinburgh (UK)

Mahlon C. Kennicutt II, Texas A&M University, (USA)

Program Committee• Robin Bell, LDEO, Columbia University (USA)

Jemma Wadham, University of Bristol (UK)Kay Bidle, Rutgers, The State University New Jersey (USA)Sergey Bulat, Petersburg Nuclear Physics Institute (Russia)

Financial Sponsors

The conference organizers wish to gratefully acknowledge the generous support of the followingsponsors for their substantial support for this conference.

Program Book Final.pdf 1 3/3/2010 11:13:14 AM

Chapman Conference on the Exploration and Study of Antarctic Subglacial AquaticEnvironments (SAE)

Baltimore, Maryland USA15–17 March 2010

Meeting At A Glance

Monday, 15 March08.30-09.00 Coffee09.00-09.30 Introductions – Session 109.30-10.30 Keynote Speaker10.30-11.00 Session 1 (cont.)11.00-11.30 Morning Break11.30-12.30 Session 1 (cont.)12.30-13.30 Lunch on your own13.30-14.30 Poster Session14.30-15.00 Session 215.00-15.30 Keynote Speaker15.30-16.00 Afternoon Break16.00-19.00 Session 2 (cont.)19.00-21.00 Dinner on your own

Tuesday, 16 March08.30-09.00 Coffee09.00-10.30 Keynote Speaker – Session 310.00-11.00 Session 3 (cont.)11.00-11.30 Morning Break11.30-12.30 Keynote Speaker12.30-13.30 Lunch on your own13.30-14.30 Poster Session14.30-15.30 Session 415.30-16.00 Afternoon Break16.00-19.00 Session 4 (cont.)19.00-21.00 Chapman Conference Dinner (reservation/prepaid)

Wednesday, 17 March08.30-09.00 Coffee09.00-11.00 Session 511.00-11.30 Morning Break11.30-12.30 Session 5 (cont.)12.30-13.30 Lunch on your own13.30-14.30 Poster Session14.30-15.30 Session 5 (cont.)15.30-16.00 Afternoon Break16.00-16.30 Panel Discussion 116.30-17.00 Panel Discussion 217.00-17.30 Panel Discussion 317.30-18.00 General Discussion and Concluding Remarks19.00-21.00 Dinner on your own


Scientific Program

Time MondayMarch 15

TuesdayMarch 16

WednesdayMarch 17

08.30. – 09.00 Coffee Coffee Coffee

IntroductionsSession 1. SAE asHabitats for Life

Session. 3Sedimentary

Records

Session 5. SAE ProjectUpdates

09.00-09.30 Introductions by Co-Chairs: Martin Siegert(UK) and ChuckKennicutt (US)

3.1 Keynote,Michael Bentley(UK) (774090)Subglacial LakeSedimentaryProcesses andSediments: PotentialRecorders of PastClimate and Ice SheetChanges

5.1 Valery Lukin (RUS)(790556)Russian Plans/Activitiesfor Drilling into andSampling Subglacial LakeVostok

09.30- 10.00 1.1 Keynote, MarkSkidmore (US)(788714)Microbial Communities inAntarctic SubglacialAquatic Environments(SAE)

3.1 Keynote (cont.) 5.2 Neil Ross (UK)(787435)Subglacial LakeEllsworth: its History,Recent Field Campaignsand Plans for itsExploration.

10.00-10.30 1.1 Keynote (cont.) 3.2 Eugene Domack(US) (787536)Subglacial LakeEnvironment andFacies Revealed byLarsen B Ice ShelfDisintegration

5.3 WISSARDSlawek Tulaczyk (UCSanta Cruz) (786551)The Whillans Ice StreamSubglacial AccessResearch Drilling(WISSARD) Project: anIntegrated Study ofMarine Ice Sheet Stabilityand Subglacial LifeHabitats in WestAntarctica


Time MondayMarch 15

TuesdayMarch 16

WednesdayMarch 17

10.30-11.00 1.2 Jill Mikucki (US)SAE (787606) BloodFalls, Antarctica:Insights into SubglacialMicrobial Energetics

3.3 SlawekTulaczyk (US)(799325)Formation andPreservation of Long-Term PaleoclimaticandPaleoenvironmentalRecords in SubglacialLake

5.4 Robin Bell (US)(799998)Melt and Freeze Coupletin Central East Antarctica

11.00-11.30 Morning Break Morning Break Morning Break

IntroductionsSession 1. SAE asHabitats for Life

(cont.)

Session 4. SAETechnologyChallenges

Session 5. SAE ProjectUpdates (cont.)

11.30-12.00 1.3 David Pearce (UK)(802774) The Search forLife in Former SubglacialLake Hodgson,Antarctica

4.1 Keynote, PeterDoran (US) (781456)EnvironmentalProtection andStewardship ofSubglacial AquaticEnvironments.

5.5 Reed Scherer (US)(787613)What Can Tiny FossilsTeach Us About WAISHistory & SubglacialProcesses?

12.00-12.30 1.4 Jemma Wadham(UK) (784567)Examining the Potentialfor Methanogensis inAntarctic SubglacialAquatic Environments

4.1 Keynote (cont.) 5.6 Sun Bo (CHINA)(783170)Glaciological andGeophysical Studies inDome A, East Antarctica

12.30-12.30 Lunch on your own Lunch on your own Lunch on your own

13.30-14.30 Poster Session Poster Session Poster Session

Session 2. SAEHydrology and Ice

Sheets Interactions

Session 4. SAETechnology

Challenges (cont.)

Session 5. SAE ProjectUpdates (cont.)

14.30-15.00 2.1 Keynote, DavidMarchant (US)Subglacial Floods(785500) TheGeomorphic Signature ofSubglacial Floods

4.2 MatthewMowlem (UK)(788555)Probe Technologiesfor The DirectMeasurement andSampling ofSubglacial LakeEllsworth

5.7 RobertBindschadler (US)(794141)Surprises Seen in theSub-Ice ShelfEnvironment


Time MondayMarch 15

TuesdayMarch 16

WednesdayMarch 17

15.00-15.30 2.1 Keynote (cont.) 4.3 David Blake(UK) (787425) TheDevelopment of aHot-Water Drill toAccess Sub-GlacialLake Ellsworth

5.8 Christoph Mayer(GER) (787528)Subglacial Lake Regimesfor Different LakeCategories

15.30 – 16.00 Afternoon Break Afternoon Break Afternoon Break

Session 2. SAEHydrology and IceSheet Interactions

(cont.)

Session 4. SAETechnology

Challenges (cont.)

Session 6. GeneralDiscussion and Future

Directions

16.00-16.30 2.2 Adrienne Block(US)(787671)The Role of SubglacialLakes in the Onset andMaintenance of RecoveryIce Stream, EastAntarctica

4.4 MichaelGerasimoff (US)(799480)UW-Wisconsin (ICDS)WISSARD DrillingProgram:EnvironmentalStewardship,Engineering, andScientific Objectives

6.1 Panel Discussion#1 – SAE Habitats,Hydrology and Ice sheetInteractions - Speakersfrom Day 1

16.30-17.00 2.3 Leigh Stearns (US)(787566)Subglacial DrainageEvents Under OutletGlacier End-members:Byrd Glacier andWhillans Ice Stream

4.5 Bill Stone (US)(787392)ENDURANCE: TwoMissions to Antarcticaand Paths toAdvanced Sub-GlacialScience Autonomy

6.2 Panel Discussion#2 - SedimentaryRecords andTechnological Challenges– Speakers from Day 2

17.00-17.30 2.4 Timothy Creyts(US) (800002)Drainage of SubglacialWater Systems BeneathIce Sheets

4.6 Alberto Behar(US) (801014)The Subglacial LakeExploration Device(SLED) Camera

6.3 Panel Discussion#3- Future Plans for SAEExploration and Research- Speakers from Day 3

17:30-18.00 2.5 Jacob Walter (US)(787310)How Well Do SubglacialLakes Act as HydraulicJacks?

4.7 Ross Powell(US) (781228)Assessing GroundingZones and Sub-Ice-Shelf Cavity ProcessesUsing Direct Samplingand RoboticInstrumentation

6.4 General DiscussionConcluding Remarks –Co-Conveners

19.00 -21.00 Dinner

On your own

ChapmanConference Dinner(reservation/prepaid)

Dinner

On your own


POSTER SESSION SCHEDULE

Poster Session will be held in the Harborview Ballroom, Monday, Tuesday, and Wednesday from 13.30to 14.30.

Achberger, A. Expression of a Bacterial Ice Binding Protein from 3,519 m in theVostok Ice Core

Barbante Trace Elements and Metalloids in Accreted Ice From Sub-glacial LakeVostok, Antarctica

Beem, L. High Resolution GPS Measurements Of Ice Surface Velocity ChangesOn And Around Active Subglacial Lakes, Whillans And Mercer IceStreams, West Antarctica

Bidle, K. The Use Of Analytical Flow Cytometry And High-Speed Cell SortingTo Assess The Abundance And Viability Of Ancient Ice Microbes

Bulat, S. Biochemical Study of Lake Vostok Accretion Ice

Carter, S. Taking The Pulse: Laser Altimetry And Radar Sounding As A MeansTo Verify Ice Sheet Water Models At Subglacial Lakes

Christner, B. Biologically and Chemically Clean Subglacial Access Drilling

Cockell, C. Subglacial Life and the Search for Life Beyond Earth

Doyle, S. Evidence for Microbial Metabolism at -15°C in an Antarctic SubglacialEnvironment

Fricker, H. Synthesising Multiple Remote Sensing Techniques for AnalysingSubglacial Hydrologic Systems: Application on MacAyeal Ice Stream,West Antarctica

Hodgson, D. Exploring Former Subglacial Hodgson Lake, Antarctica:Geomorphology, Limnology and Palaeoimnology

Jean Baptiste, P. New Helium Isotope Measurements In The Accreted Ece of TheSubglacial Lake

Jiang, J. Scanning Detection Of Multiscale Significant Trend-Changes In Ice-core Records

Langley, K Low-frequency Radar Profiles of the Recovery Lakes

Leitchenkov, L. Potential Proxies Held in Sediment Inclusions From Ice Cores Of TheVostok Station Borehole


MacGregor, A. Modeling The Spatial Variation Of Englacial Radar Attenuation:Application To The Vostok Flowline and Implications For TheDetection of Subglacial Lakes

Matsuoka, K. Detecting Wet Ice-sheet Beds Across Antarctica Using Radar: AFeasibility Assessment Using Three-dimensional Temperature AndRadar Attenuation Models

Pattyn, F. Antarctic Subglacial Lake Discharges

Peters, L. Seismic Imaging Of The Subglacial Plumbing System

Scambos, T. A Sudden Outburst Flood Event Beneath Crane Glacier: Evidence,Causes, and Ice Dynamic Effects

Schroeder, D. Comparative Subglacial Hydrology of Thwaites Glacier, WestAntarctica, Using Basal Specularity

Siegert, M. Subglacial Lake Vostok: A Review of Geophysical Data regarding ItsPhysiographical Setting

Takano, Y. Enantiomer-specific Isotope Analysis For Chiral Amino Acids inAntarctic Sub-glacial Environment: Proposal

Takano, Y. Crustal Uplifting Rate Associated With Late-Holocene Glacial-isostaticRebound at Skallen and Skarvsnes, Lützow-Holm Bay, EastAntarctica: Evidence of a Synchrony in Sedimentary and BiologicalFacies on Geological Setting

Tranter, M. Chemistry of Vostok Accretion Ice And Pore Waters Beneath TheKamb and Bindschadlers Is Consistent With Microbial Life BeneathThe Antarctic Ice Sheet

Vick, T. Microbial Responses During The Transition To Polar Night inPermanently Ice-covered Antarctic Lakes Trista J. Vick and John C.Priscu Montana State University, Department of Land Resources andEnvironmental Science, 334 Leon Johnson Hall, Bozeman, Montana,59717

Vogel, S. On The Role of Subglacial Bio/Geochemical Processes In GlobalBiogeochemical Cycles - Results From Kamb Ice Stream AndANDRILL

Wright, A. The Identification And Physiographical Setting of Antarctic SubglacialLakes: An Update Based On Recent Discoveries


ABSTRACTS

Expression of a Bacterial Ice BindingProtein from 3,519 m in the Vostok IceCore

Achberger, Amanda Achberger Amanda M;Brox Timothy; Raymond James A; DoyleShawn M; Christner Brent Craig; SkidmoreMark L A.M. Achberger, S.M. Doyle, B.C.Christner, Biological Sciences, Louisiana StateUniversity, Baton Rouge, LA; T. Brox, M.L.Skidmore, Department of Earth Sciences,Montana State University, Bozmen, MT; J.A.Raymond, , University of Nevada, Las Vegas,NV

A bacterium recovered from the Vostok icecore at a depth of 3,519 m was found topossess an ice binding protein (IBP)homologous to those found in some cold-adapted marine bacteria and diatoms. TheIBPs which have been described have beenshown to alter the freezing andrecrystallization processes in ice. Comparisonof the ice crystalline structure in samplesfrozen with and without the IBP from theVostok bacterial isolate demonstrates its abilityto alter the ice structure, which could providecells in the cryosphere with distinct survivaladvantages. Experiments on the temperature-dependent regulation of the IBP gene indicatedthat it was expressed at 4 degrees C, but notat temperatures above 10 degrees C. Ourresults provide evidence for a molecularadaptation to icy conditions and for a lowtemperature stress response that appearsdistinct from the classical bacterial cold-shockresponse.

Trace Elements and Metalloids in AccretedIce From Sub-glacial Lake Vostok,Antarctica

Barbante, Carlo Barbante Carlo; PlanchonFridiric; Hong Sungmin; Gabrielli Paolo;Gabrieli Jacopo; Turetta Clara; BoutronClaude; Petit Jean-Robert; Bulat Sergey;Hong Sungmin; Cescon PAolo; CairnsWarren; Cozzi Giulio C. Barbante, J. Gabrieli,P. Cescon, Environmental Sciences, Universityof Venice, Venice, ITALY; P. Gabrielli, ByrdPolar Research Center, The Ohio StateUniversity, Columbus, OH; F. Planchon, Sectionof Geochemistry - Geology Department, RoyalMuseum for Central Africa, Bruxelles,BELGIUM; C. Boutron, J. Petit, LGGE, CNRS,Grenoble, FRANCE; S. Bulat, Division of

Molecular and radiation Biophysics, PetersburgNuclear Physics Insitute, RAS, St Petersburg,RUSSIAN FEDERATION; S. Hong, S. Hong,Polar Sciences, KOPRI, Incheon, KOREA,REPUBLIC OF; C. Barbante, F. Planchon, P.Gabrielli, J. Gabrieli, C. Turetta, W. Cairns, G.Cozzi, IDPA, CNR, Venice, ITALY

We report here the abundances of 25 elements(Li, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Cu,Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Sb, Ba, Pb, Bito U) and REE concentration determined byICP-SFMS in the deepest of the Vostok icecore. The reliable determination of thesemetals and metalloids has been performed inthe different types of ice encountered below3271 m until 3659 m depth corresponding toatmospheric ice, glacial flour and to accretedice originating from the freezing of Lake Vostokwaters. From atmospheric ice and glacial flour,the relative contributions of primary aerosolswere evaluated for each elements usingchemical mass balance approach in order toprovide a first order evaluation of theirpartition between soluble (sea-salt) andinsoluble (wind-blown dust) fraction in the ice.Sea-salt spray aerosols are the main source ofimpurity to the ice and contribute largely toNa, Mg and K levels, and in a lesser extent toCa, Sr, Rb, Li and U. For other elements suchas Al, V, Cr, Mn, Fe, Co, Cu, Zn, Mo, Sb, Baand Pb as well as the non sea salt fraction ofMg, K, Ca, Sr, Rb, Li and U, dust inputs appearto primarily control their deposition variability.For As, Se, Ag, Cd and Bi, primary aerosols arenot consistent with the observed levels andother sources are likely important. For theglacial flour, the comparable levels of elementswith the overlying atmospheric ice suggest thatincorporation of abrasion debris at the glaciersole is limited in the sections considered. Forthe accreted ice originating from the subglacialLake Vostok, a contrasting situation isobserved between a solute-rich accreted type-1 where large aggregates are encountered andsolute-poor accreted ice type-2 devoid of anyvisible inclusions.

High Resolution GPS Measurements Of IceSurface Velocity Changes On And AroundActive Subglacial Lakes, Whillans AndMercer Ice Streams, West Antarctica

Beem, Lucas Beem Lucas; Tulaczyk SlawekM; Walter Jake; Joughin Ian R; SmithBenjamin Eaton; Fricker Helen Amanda L.Beem, S.M. Tulaczyk, J. Walter, , University of


California Santa Cruz, Santa Cruz, CA; I.R.Joughin, B.E. Smith, Applied PhysicsLaboratory, University of Washington, Seattle,WA; H.A. Fricker, Scripps OceanographicInstitute, University of California San Diego,San Diego, CA

In late 2006 an extensive subglacial watersystem was discovered beneath Whillans andMercer ice streams, West Antarctica, using IceCloud and land Elevation Satellite (ICESat)laser altimeter data. A more comprehensive,continent-wide study has now detected morethan 120 active lakes. Active subglacial lakesare the most dynamic known elements ofAntarctic subglacial hydrology and can createregional-scale changes in the distribution andpressure of subglacial water, which could affectice flow rates. Ice streams can go throughlarge changes in flow patterns over shortperiods of time. The Kamb Ice Streamstagnated very rapidly ~150 ybp.Observations show Whillans Ice Stream isslowing and widening. Much of the modulationof ice stream dynamics is believed to derivefrom changes in basal conditions, whichinclude variations in subglacial water pressure,hydrological drainage patterns and thermalregime. The active lakes detected by ICESathave shown patterns of filling and draining onthe timescale of just six years (2003-2009),with total basal water flux of multiple km3 a-1below the Whillans Ice Stream alone. In late2007, we deployed ten continuous GlobalPositioning System (GPS) receivers directlyover and proximal to two of the lakes of theWhillans/Mercer system: Subglacial LakesWhillans (SLW) and Mercer (SLM). This datapermits analyses of subglacial lake levelvariations and coincident velocity fluctuations;it also provides a continuous record of lakeactivity, whereas ICESat only samples twice ayear. At the time of the Chapman Conference,more than two years of data will have beenacquired that document surface velocity andelevation changes in this region. Over thisperiod, SLM has filled consistently. Preliminaryresults provide no clear evidence that surfacevelocity above and adjacent to SLM has beensignificantly influenced by this lake filling. SLWfilled for at least the first 14 months ofobservation and drained in mid 2009; GPSprovides the exact timing of the drainage.Precise knowledge of SLW’s activity isespecially important because the lake will bedrilled in 2012-2013 by the WISSARD project.The results of our survey will offer insights intothe effects of the dynamics of the Whillans IceStream and the ultimate goal of deriving aconstitutive relationship, which accuratelydescribes the dependence of ice stream flow on

activity of subglacial lakes, that can beincorporated into prognostic ice sheet models.

The Subglacial Lake Exploration Device(SLED) Camera

Behar, Alberto Behar Alberto Enrique A.E.Behar, In Situ Instruments, NASA/JPL,Pasadena, CA

SLED camera: The Subglacial Lake ExplorationDevice (SLED) camera is a miniaturized,propelled, ice-borehole optical recording devicedesigned to observe the borehole iceproperties, water-ice > interface, distributionof basal debris, suspended particles in >water columns, and sediment surfaceproperties. The development of SLED issupported by NASA under a separate Award.SLED will perform the following functions atboth SLW and the grounding-line sites: recordthe borehole ice properties, investigate themarine ice interface, examine distribution ofentrained debris in basal ice, observe geometryof ice-water interface; inspect the watercolumn for suspended particles as well aspossible aquatic organisms, search for visualevidence of water stratification and/orhorizontal/vertical motion; investigate thesea/lake floor for evidence of erosional andsedimentary processes (glacial flutings,subaqueous sediment failures, debris flows,deltas, drainage channels, etc.), record signsof possible bioturbation and/or evidence ofbenthic organisms. Algal mats have beenobserved on the sea floor beneath the recentlydisintegrated Larsen Ice Shelf (Domack et al.,2005) and marine crustaceans at the edge ofthe grounded ice of the more open marineenvironment at McKay Glacier (Powell et al.,1996). In addition to biological exploration, weintend to use the camera to examine thestructures of the sea floor, looking for evidenceof grounding zone wedges that may mark thehistoric location of the grounding line duringglacier retreat episodes (Anderson and Shipp,2001). We will design the camera to look up atand across the base of the ice shelf. This first-ever view may well reveal aspects of the >ocean-ice heat and mass exchange processes,which may depend on interface roughness.

Melt and Freeze Couplet in Central EastAntarctica

Bell, Robin Bell Robin E; Creyts Timothy T;Wolovick Mike; Spector Perry; StudingerMichael; Jordan Tom A; Frearson Nick;Ferraccioli Fausto; Corr Hugh; Braaten DavidAlan; Damaske Detlef R.E. Bell, T.T. Creyts,M. Wolovick, P. Spector, M. Studinger, N.


Frearson, , Lamont-Doherty Earth Observatoryof Columbia University, Palisades, NY; D.A.Braaten, Center for Remote Sensing of IceSheets, Kansas University, Lawrence, KS; T.A.Jordan, F. Ferraccioli, H. Corr, , BritishAntarctic Survey, Cambridge, UNITEDKINGDOM; D. Damaske, , Federal Institute forGeosciences and Natural Resources, Hanover,GERMANY

The Gamburtsev Subglacial Mountains,encased in 1-4.5 kilometers of ice, are themost poorly understood mountain range onEarth. During the International Polar Year, thefirst systematic aerogeophysical survey wasflown over this region and acquired over120,000 line km of laser, radar, gravity andmagnetic data. These deeply dissectedmountains ranges are characterized by a welldeveloped alpine valley system with largecirques along the ridge lines. Along thesoutheastern edge of the GamburtsevMountains, along a valley head, the ice sheetinternal layers are deflected downwards over aregion 12 km long and 4 km wide. In thisvalley head, internal layers that are regionallyover 750m above the ice sheet bed intersectthe base of the ice sheet. This distinctivepulled-down geometry of the internal layerssuggests that up to 20km3 of ice has beenremoved at melt rates up to centimeters peryear. Discontinuous bright basal reflectors100-500m long in the valley suggest basalwater in pockets. Any water produced bybasal melt would be driven down thehydrologic potential to the east into a 20 kmlong 2-3.5 km wide east-west trending valleybounded by 150-200m high hills. Along thenorthern (upflow) side of the valley, a distinctinternal reflector emerges from the valley wallin the typically echo-free base of the ice sheet.This near-bed internal layer can be clearlytraced up to 10 km to the south of the valley.The near-bed reflector is generally found150m- 700m above the base of the ice sheetand has amplitudes of 10-30dB. The low endof the amplitudes is similar to the internallayers at the same depth while the high end ofthe amplitude is similar to the reflection fromthe ice sheet bed. We interpret this strongnear-bed reflector as the contrast between themeteoric and basal freeze-on (accretion) ice.At the eastern end of the east-west trendingvalley, the bright reflector bulges over thesouthern edge of the bounding hills. Abovethis near-bed reflector bulge, the internallayers are conformable with the near-bedreflector and not the underlying topography.We interpret these unusual internal layers as amelt freeze couplet. The drawn down internallayers point towards the production of basal

melt while the strong near-bed reflector isindicative of freezing to the base of the icesheet. These melt-freeze events likely occurover much longer periods than dynamicobservations have been made. The widespreadaccretion of 100’s of meters of ice to the baseof the ice sheet would have ramifications forice sheet mass balance, accumulation, icesheet models and the fidelity of ice cores.

Subglacial Lake Sedimentary ProcessesAnd Sediments: Potential Recorders ofPast Climate And Ice Sheet Changes

Bentley, Michael Bentley Michael;Christoffersen Poul; Hodgson Dominic;Tulaczyk Slawek M; Smith Andrew; Le BrocqAnne M M. Bentley, A.M. Le Brocq,Department of Geography, University ofDurham, Durham, UNITED KINGDOM; P.Christoffersen, Scott Polar Research Institute,University of Cambridge, Cambridge, UNITEDKINGDOM; D. Hodgson, A. Smith, , BritishAntarctic Survey, Cambridge, UNITEDKINGDOM; S.M. Tulaczyk, Earth and PlanetarySciences Department, University of California,Santa Cruz, CA

The development of funded programs to drillinto Antarctic subglacial lakes means that thereis an imminent prospect of retrieving the firstsediments from an extant lake. Thesesediments are potentially important for at leastthree reasons. Firstly they may record changein the conditions at the base of the ice sheet.For example, it is possible that the compositionof subglacial lake sediment may vary onglacial-interglacial cycles, with varyingamounts or composition of dust or othercomponents of sedimentary input, or episodicchange from movement of subglacial water.Second, some lakes may preserve non-glacialsediments from intervals of ice sheet retreat orcollapse, or from preglacial conditions. In boththese cases a major attraction of usingsubglacial sediment is that many lakes arethought likely to contain sedimentssubstantially older than the record provided byice cores. The third reason is that thesediments may not only act as a habitat forlife, particularly at the relatively nutrient-richsediment-water interface, but they may alsopreserve a record of past life in the form oforganic goechemicals, including DNA, in thesediment. In order to assist future planning,site selection, and identifying appropriateanalytical techniques, we review what is knownabout sediments from formerly subglacial lakesin Antarctica and elsewhere, including fromboth geophysical data and direct sampling. Wealso discuss what we might reasonably


speculate about their physical characteristicsfrom analogies with surface glacier-fed andglacier-contact lakes, and from knownlimnological and glaciological processes. Thisincludes consideration of the three likely mainpathways for sediment for subglacial lakesediment: rain-out of englacial sediment at thelake ceiling, rain-out of subglacial sedimentfrom basal debris layers, and transport ofsediment by meltwater drainage into the lake.We also discuss the likely sediment-landformassociations that may exist along subglaciallake margins. From this we develop aconceptual model of subglacial lakesedimentation, focussing especially on likelyprocesses and sediments in lakes Vostok,Whillans and Ellsworth. Finally, we discuss theimplications of the likely sedimentcharacteristics for the coring technologies thatwill be adopted to retrieve such sedimentsequences.

The Use Of Analytical Flow Cytometry AndHigh-Speed Cell Sorting To Assess TheAbundance And Viability Of Ancient IceMicrobes

Bidle, Kay Bidle Kay; Natale Frank K. Bidle,F. Natale, Marine and Coastal Sciences,Rutgers University, New Brunswick, NJ

It is currently unknown whether ancient icesamples, which have been exposed to harshenvironmental conditions, are amenable toflow cytometry and high speed cell sorting,even though these analytical techniques poseseveral major advantages. For example, theyrequire small sample volumes (<1 ml) foranalysis, while yielding extensive informationon cell abundance and physiological state.They are also amenable to single cellgenomics, which provides unprecedentedaccess to the genomic material of yet-uncultured taxonomic groups, greatlyfacilitating the discovery of novel metaboliccapabilities. We applied emerging techniques inanalytical flow cytometry to quantify the totaland metabolically active microorganisms inAntarctic ice samples ranging 100 Kyr to 8Myr, in order to assess the relative proportionof viable vs. dead cells and to explore geneticstrategies of DNA repair in ancient icemicrobes. We recently established that, evenafter 8 million years of cosmic radiationbombardment, viable microbes and microbiallyderived DNA could be recovered from buriedglaciers in the Dry Valleys of the TransantarcticMountains, Antarctica. Given the stronginfluence of cosmic flux on DNA degradation inancient ice samples, we hypothesize that thedegree of DNA damage increases with time and

that viable 8 Myr old bacteria possessparticularly effective and novel DNA repairmechanisms for which we can obtain geneticsignatures. Our analyses suggest thatfluorescence staining and flow cytometryanalysis is feasible for microbes encased inancient ice. We have been able to opticallydiscriminate between abiotic, glacial tillparticles and nucleic acid-containing, bacteriain our ice meltwater samples upon stainingwith SYBR-Gold or SYTO-13 and ultimatelydetermine the microbial abundance. At thesame time, we used flow cytometry to assessice microbe viability with fluorescentLIVE/DEAD stains and relate the percentviability to ice age. We discriminated betweenactive and dormant bacteria via markers forrespiratory activity by staining dilute meltwatercultures with the redox dye 5-Cyano-2,3-Ditolyl Tetrazolium Chloride (CTC), which isreduced intracellularly in respiring cells to aninsoluble, fluorescent precipitate. Based on oursample types (i.e., microbes encased in afrozen state for at least 100 Kyr), our resultssuggest that the maximum recommendedconcentration (5 mM) and extended incubationtimes (24 h) are necessary to detect activemicrobes in these samples, given theirinherently low metabolic rates and growthrates in situ.

Surprises Seen In The Sub-Ice ShelfEnvironment

Bindschadler, Robert Bindschadler Robert;Behar Alberto Enrique; Truffer Martin;Stanton Timothy P; Kim Stacy R.Bindschadler, , NASA, Greenbelt, MD; A.E.Behar, , Jet Propulsion Laboratory, Pasadena,CA; M. Truffer, Geophysical Institute,University of Alaska, Fairbanks, AK; T.P.Stanton, , Naval Postgraduate School,Monterey, CA; S. Kim, , Moss Landing MarineLaboratories, Monterey, CA

We are pursuing the hypothesis that the heatof ocean waters is responsible for increased icethinning, retreat and flow acceleration of theice sheet edge in the Pine Island region ofWest Antarctica. While awaiting sufficientlogistic support to begin sustained oceanprofiling and directly observe the sub-ice-shelfenvironment of the Pine Island Glacier iceshelf, our novel methods were tested duringthe 2009-2010 field season in Windless Bight,20 miles northeast of McMurdo Station,Antarctica. There, an 8-inch diameter accesshole was drilled through the 180-meter thickice shelf using a relatively light andtransportable hot-water drilling system. Aborehole camera revealed the scalloped nature

of the melted borehole, obtained what webelieve to be the first-ever pictures of theunderside of an ice shelf, and captured video ofa Lyssianasid amphipod as it explored ourborehole. Upon recovery, we also discoveredwhat appear to be jelly tentacles on thecamera cable. Proof of higher life forms morethan 20 kilometers from even seasonally openwater and underneath thick floating icesuggest a more expansive biological footprintin the Ross Sea region than previously held.Initial ocean profiler data collected upon initiallowering into the 800-meter deep water cavityconfirm expected values of salinity andtemperature. Subsequent profiles will providemore valuable data on the temperature,salinity and current structure and how thesevary with time, including tidally forcedoscillations.

The Development of a Hot-Water Drill toAccess Sub-Glacial Lake Ellsworth

Blake, David Blake David M D.M. Blake,Technology & Engineering, British AntarcticSurvey, Cambridge, UNITED KINGDOM

Access to Sub-Glacial Lake Ellsworth (SLE) isscheduled for the 2012/13 Antarctic summerseason. A hot water drill is to be developed toproduce an initial hole diameter of 36centimetres to enable an instrumented probeto enter the lake. The design of the drill willbuild on previous concepts and developmentsused by the British Antarctic Survey (BAS) forhot water drilling in Antarctica. SLE is to thesouth of the Ellsworth Mountains and with aground transportation route to a blue icerunway at Patriot Hills. For the drillingprogramme at SLE, all equipment, materialsand fuel will be carried from South America toPatriot Hills via airborne heavy lift. With amaximum aircraft load of 19 tonnes, attentionto the maximum size of components and theoverall weight is necessary to ensure materialscan be transported by air. The drilling hose atover 3200 metres and the winch will be thelargest component needed to be transported asone item. A procedure has been produced andwill be adopted to ensure all of the componentsare cleaned before they are used at SLE.Biological filtering will be employed to removeviruses and product from the water supply.The electrical supply, pumps and ancillaryitems will be housed in a field camp adjacentto the access hole. Sufficient fuel is to beprovided in 205 litre drums to support the fieldsite and enable two separate accesses of thelake. The drill is being developed andassembled at BAS in Cambridge and will be

tested before delivery to SLE.

The Role of Subglacial Lakes in the Onsetand Maintenance of Recovery Ice Stream,East Antarctica

Block, Adrienne Block Adrienne E; Bell RobinE; Flowers Gwenn E; Pimentel Sam;Studinger Michael; Frearson Nick A.E. Block,Earth and Environmental Sciences, ColumbiaUniversity, New York, NY; A.E. Block, R.E.Bell, M. Studinger, N. Frearson, , Lamont-Doherty Earth Observatory, Palisades, NY; S.Pimentel, Department of Earth and OceanScience, University of British Columbia,Vancouver, British Columbia, CANADA; G.E.Flowers, Department of Earth Sciences, SimonFrasier University, Burnaby, British Columbia,CANADA;The Recovery Ice Stream drains 8

Biogeochemical Study of Lake VostokAccretion Ice

Bulat, Sergey Bulat Sergey; Alekhina Irina;Chuvochina Maria; Lipenkov Vladimir; LukinValery; Barnola Jean-Marc; WagenbachDietmar; De Angelis Martine; LeitchenkovGerman L; Marie Dominique; NormandPhilippe; Petit Jean-Robert S. Bulat, I.Alekhina, M. Chuvochina, , Petersburg NuclearPhysics Institute, St Petersburg, Gatchina,RUSSIAN FEDERATION; V. Lipenkov, V. Lukin,, Arctic and Antarctic Research Institute, StPetersburg, RUSSIAN FEDERATION; S. Bulat,I. Alekhina, M. Chuvochina, J. Barnola, M. DeAngelis, J. Petit, , Laboratory of Glaciology andGeophysics of Environment CNRS, Grenoble,FRANCE; D. Wagenbach, Institut furUmweltphysik, University of Heidelberg,Heidelberg, GERMANY; G.L. Leitchenkov, ,Institute for Geology and Mineral Resources ofthe World Ocean, St Petersburg, RUSSIANFEDERATION; D. Marie, , Station Biologique deRoscoff, Roscoff, FRANCE; P. Normand,Ecologie Microbienne, Universite ClaudeBernard-Lyon I, Lyon, FRANCE

The objective was to perform complexbiogeochemical study of accretion ice of thesubglacial Lake Vostok, East Antarctica withthe ultimate goal to discover alien life in thisextreme icy environment. The additional taskwas to prove our previous scenario (Bulat etal., 2004) by complementary analysesincluding gas content, dissolved organic carbon(DOC), major ion chemistry, mineralogy ofsediments, microbial cell enumeration and 16SrRNA genes sequencing. As a result, total gascontent proved to be 2-3 orders of magnitudelower than in glacier ice. Meanwhile a giant


mica-clay sediment inclusion within the mono-crystal lake ice showed an unusual content ofoxygen, carbon dioxide and methane. MeanDOC levels were found to be less than 20 pbb.Major ion chemistry showed enrichment ofmagnesium and calcium sulfates along withsulfides in ice with sediment inclusions only.Amongst the latter sulfide minerals like pyritewere also identified. Accordingly, possibleredox couples are rather limited in supportingchemolithoautotrophic life forms. Themolecular microbiology study constrained byAncient DNA research criteria showed that theice until depth 3659 m contains the very lowmicrobial biomass (Table 1). The only icecontaining mica-clay inclusions allowed thedetection of unusual gas content and recoveryof few bacterial phylotypes all passingcontaminant controls but not fitting groupsexpecting to discover. The latter included thewell-known chemolithoautotrophic thermophile(unexpected). In contrast, the deeperaccretion ice with no sediment present and gascontent close to detection limit gave no reliablesignals. Since Antarctic subglacial lakeenvironments are thought to analogues forextraterrestrial icy environments, their abilityto support microbial life is willingly consideredunquestionable. However, amongst them theLake Vostok can be viewed as very special withextremely low biomass giant aquatic body onthe Earth, exploration of which is highly proneto forward-contamination.

Russian Plans/Activities For Drilling IntoAnd Sampling Subglacial Lake Vostok

Bulat, Sergey, Bulat Sergey; Lukin Valery S.Bulat, , Petersburg Nuclear Physics Institute,St. Petersburg, RUSSIAN FEDERATION; V.Lukin, Arctic and Antarctic Research Institute,St. Petersburg, RUSSIAN FEDERATION

The Russian Federation has developed anational ongoing project on the drilling into,and sampling of, subglacial Lake Vostok, EastAntarctica. The goal is to explore this extremeicy environment in a multifaceted way, toidentify the form and levels of file that existthere. The project is funded by the RussianFederal Service for Hydrometeorology andEnvironmental Monitoring (ROSHYDROMET)and is available for open for collaboration. Inthe season 2009/2010 drilling operations willbe restarted from the depth 3559 m (about150 m towards ice-water boundary) in the newborehole called 5G-2 (previously in the2008/2009 season within the 5G-1 boreholethe drill stack was lost as a consequence ofborehole inclination).The 2009/2010 seasonwill be devoted to developing the deep the

borehole between 3680 and 3690 m. The newaccretion ice including the inclusion-rich‘thermophile-containing’ horizon (Bulat et al.,2004; Lavire et al., 2006) (around 3608 m)will again be recovered and its complexitystudied. The following season (2010/2011) thedrill will enter the lake. This entry will beperformed using a thermal drill and cleansilicone oil as a drill liquid, which will replacethe kerosene mix at the borehole bottom.During the lake entry sensors for oxygencontent (and some other parameters) will beinvoked to get the initial gas values directly atthe moment of the contact. In addition, thelake water will be supposedly sampled intospecial wall-warmed bathometers placed withinthe drill to be studied unfrozen in clean labs.The season after (2011/2012) the lake waterraised up to dozens meters within the borehole5G-2 and subsequently allowed to freeze willbe re-drilled to get sharply frozen lake water(from different horizons ranging from dirty atthe top to clean at the bottom) for latercomplex investigation. During that season, orthe season after a special set of biophysicalinstruments developed now in the PetersburgNuclear Physics Institute (now a member ofRussian national research centre for nuclearphysics and nanotechnology - Science, 2009,461, 1028) will be sent into the water bodywith a battery of common ocean observatorysensors, visible and infra-red light cameras,spectrometers/fluorimeters and special watersamplers loaded on a board of severalsubmersible titan modules, firstly as ROVshooked on a special line and operated with thehelp of a trolling reel and then - as AOVs. Suchactivities will be in a line with environmentalstewardship in exploration of unique aquaticenvironments under the thick Antarctic icesheet.

Taking the “Pulse:” Laser Altimetry andRadar Sounding As A Means To Verify IceSheet Water Models At Subglacial Lakes.

Carter, Sasha Carter Sasha P; Fricker HelenAmanda; Blankenship Donald D; LipscombWilliam H; Price Stephen F; Johnson Jesse V;Young Duncan A S.P. Carter, H.A. Fricker,Cecil H and Ida M. Green Institute ofGeophysics and Planetary Physics, ScrippsInstitution of Oceanography, UC San Diego, LaJolla, CA; D.D. Blankenship, D.A. Young,Institute for Geophysics, University Of TexasAustin, Austin, TX; W.H. Lipscomb, S.F. Price, ,Los Alamos National Laboratory, Los Alamos,NM; J.V. Johnson, , University of Montana,Missoula, MT


With the recent multiyear acquisition ofsatellite laser altimetry, it is now possible toobserve the movement of subglacial waterthrough entire basins. The last four decades ofairborne radar sounding campaigns havebrought unprecedented resolution of icethickness, ice structure and basal propertiesfor nearly the entire Siple Coast drainage.Within the last decade several models havebeen developed and implemented to explainboth the production and transport large scaletransport of water beneath the Antarctic icesheet. Recent advances to the classicaljökulhlaup theory have been developed toexplain the timing, magnitude, and evolution ofepisodic subglacial water flow. Verification ofboth the long term transport and floodevolution models has been limited to massbudgets for entire basins or focused onindividual events. Using an thermomechanicalice sheet model to provide engalcialtemperatures distribution and basal melt rate,RES data on ice thickness and basal reflectionswe develop self consistent method formodeling basal water distribution and imagingbasal water systems. This model is thentested in several locations throughout the SipleCoast where subglacial lakes are known tocluster and for which a hydraulic linkage hasbeen demonstrated. Even the older RES dataproves highly useful for linking individual lakes.The satellite altimetry often reveals lakespreviously undetected, but still visible in theRES data. In summary close coupling of themultiple lines of geophysical data with an icesheet model has the potential to reveal aunprecedented level of detail about thesubglacial water system and its affect on theflow of the overlying ice.

Biologically and Chemically CleanSubglacial Access Drilling

Christner, Brent Christner Brent Craig; PriscuJohn C; Mikucki Jill; Gerasimoff Michael;Bolsey Robin; Lebar Done; Bentley Charles RB.C. Christner, , Louisiana State University,Baton Rouge, LA; J.C. Priscu, , Montana StateUniversity, Bozeman, MT; J. Mikucki, ,Dartmouth College, Hanover, NH; M.Gerasimoff , R. Bolsey , D. Lebar, C.R. Bentley,, University of Wisconsin, Madison, WI

Environmental stewardship is a foremostpriority during the exploration of pristineAntarctic subglacial environments. TheWISSARD (Whillans Ice Stream SubglacialAccess Research Drilling) project willimplement the biologically and chemicallycleanest technologies practicable during allphases of drilling and subglacial access. A

2007 National Research Council report(Exploration of Antarctic Subglacial AquaticEnvironments: Environmental and ScientificStewardship) and the Scientific Committee onAntarctic Research 2009 Code of Conduct forthe Exploration and Research of SubglacialAquatic Environments recommend that thenumbers of microbial cells contained in or onthe volume of any material or instrumentsadded to or placed in these environmentsshould not exceed that present in anequivalent volume of deep ice. We intend toconform to these recommendations and plan torigorously test the technology prior to anyattempt at subglacial access. To penetrate the700-800 m of overlying ice, a hot water drillingsystem has been designed which will haveapproximately 80 L min flow capacity and becapable of drilling and maintaining holes of upto 25 cm in diameter for 8 days. Integratedwithin the drilling system are large-scale waterpurification, filtering, ultraviolet radiation, andheat sterilization modules, which will removedissolved organic carbon (DOC) species andsterilize the effluent. The volume of liquidwater generated when drilling each boreholewill be at least 41 m the residence time ofwater through the system is approximately 8.5hours, and after 8 days of borehole operations,the borehole fluid should be completelycirculated through the system at least 20 times(~920 m3). Thesespecifications, together with the estimatedconcentration of cells and DOC in the ice andfrom contamination, were used to determineWISSARD clean system requirements. Tocontinuously purge contaminants during 8 daysof borehole operations, our clean accessdrilling system requires the capacity to removeat least 9 x 10 cells and 5 kg of DOC from thedrilling fluid. http://brent.xner.net/

Subglacial Life and the Search for LifeBeyond Earth

Cockell, Charles Cockell Charles; McKayChristopher P; Voytek Mary A; Doran Peter T;Siegert Martin John; Pearce David; TranterMartyn; Wadham Jemma L; BagshawElizabeth A C. Cockell, , Open University,Milton Keynes, UNITED KINGDOM; M. Tranter,J.L. Wadham, E.A. Bagshaw, , University ofBristol, Bristol, UNITED KINGDOM; M.A.Voytek, , NASA Headquarters, Washington DC,WA; D. Pearce, , British Antarctic Survey,Cambridge, UNITED KINGDOM; C.P. McKay, ,NASA Ames Research Centre, Moffett Field,CA; P.T. Doran, , University of Illinois, Chicago,IL; M.J. Siegert, , University of Edinburgh,Edinburgh, UNITED KINGDOM

The assessment of the habitability of otherplanetary bodies is necessarily constrained bywhat we know about life on the Earth.Increasingly, the community has recognisedthat some of the most promising sites forprebiotic chemistry or extant life beyond Earthare subglacial environments. Theseenvironments include: the ocean of the Jovianmoon, Europa, and possibly Callisto; bodies ofliquid water within the Saturnian moons,Enceladus and Titan; and subglacialenvironments on Mars. Subglacialenvironments on the Earth are likely to differfrom these environments in some importantrespects, such as the presence ofallochthonous organic carbon in terrestrial icesproduced by the photosynthetic biosphere.However, the diversity of anaerobic redoxcouples using elements derived from thelithosphere and gases produced in situ provideimportant insights into the thermodynamic andkinetic constrains to life in extraterrestrialsubglacial environments. Furthermore, thecontamination control procedures andexploration technologies used to exploreterrestrial subglacial environments yield newprocedures and ideas for the sampling andanalysis of extraterrestrial subglacialenvironments.

Subglacial Lake-district Reveals EastAntarctic Heat Flux Anomaly

Corr, Hugh Corr Hugh; Hindmarsh Richard CA; Ferraccioli Fausto; Armadillo Egidio;Jordan Tom A H. Corr, R.C. Hindmarsh, F.Ferraccioli, T.A. Jordan, , British AntarcticSurvey, Cambridge, UNITED KINGDOM; E.Armadillo, Dipartimento per lo Studio delTerritorio e delle Sue Risorse, Universita’ diGenova, Genova, ITALY

Unlike the West Antarctic ice sheet, which liesover a crustal rift that has volcanism on itsflanks and associated elevated geothermalheat flux, the East Antarctic ice sheet (EAIS)lies on generally aseismic continental crust thatexhibits little volcanic activity. The majority ofsubglacial lakes found in EAIS are believed tobe formed because at a ‘normal’ backgroundgeothermal heat flux of ~50 mW m-2, the iceis sufficiently thick to be at the pressuremelting point. Here we identify from icesounding radar data from East Antarctica acluster of six subglacial lakes, within a circulararea of radius 70 km. One of the lakes, whichsits astride an ice-divide, has a clear downwarping of internal layers. A forward model isused to match the layer trajectory and showsthat the subglacial melt rate to be very muchgreater than typical values for East Antarctica

and the estimated geothermal heat flux isthree times the assumed continentalbackground. The estimated volume ofproduced melt water is discussed. We showthat the enhanced geothermal heat fluxrequired for melting coincides with a graniticbody, and contend that the elevated heat iscaused by radiogenics rather than volcanism.The subglacial lake-district and underlyinggranitic body marks the inland boundary of theCook Ice Streams; a body of ice with anestablished retreat signature. Between theupstream lake-district and the ice-shelfterminus lies a hitherto undiscoveredsubglacial basin. There is widespread evidenceof water within the deep basin. Mechanismsby which the lubricated bed of the ice streamcould affect ice-sheet dynamics in the area arediscussed. Although the water depth of thelake is unknown the high melt-rate of theoverlying ice column suggests a shortresidency time. The lake is identified as atarget to drill through and recover a sedimentcore that could potentially reveal the Pliocenehistory of EAIS.

Drainage of Subglacial Water SystemsBeneath Ice Sheets

Creyts, Timothy Creyts Timothy T; SchoofChristian T.T. Creyts, Lamont-Doherty EarthObservatory, Columbia University, New York,NY; C. Schoof, Earth and Ocean Sciences,Univ. British Columbia, Vancouver, BritishColumbia, CANADA

Dynamic lakes that cause ice surface elevationchange require ample generation and supply ofwater from upstream sources. The hydraulicsystem delivers water to these lakes eitherthrough a distributed or channelizedmorphology. In this paper, we investigate theeffects of subglacial water drainage resultingfrom spatially distributed water sheets. In ourmodel, the weight of overlying ice is supportedby both water pressure and various sizes ofbed protrusions that penetrate the watersheet. Each of the various sizes bears adifferent magnitude of the overlying ice basedon a linear stress recursion that balancesforces at the bed. Previous results have shownthat water depth can be a multi-valuedfunction of both effective pressure (iceoverburden minus water pressure) that drivessheet closure and hydraulic gradient thatdrives water flow (Creyts and Schoof, 2009).Curvature and structure of this multi-valuedwater depth function depend on the protrusionsize distribution. Switches between differentbranches of the water depth relationshipcorrespond to either the establishment or shut-


down of a ‘connected’ (or efficient) drainagesystem. We build upon and extend previouswork to show how along-path discharge affectswater depth and switches from one state toanother. We conclude by relating statebehavior to subglacial conditions wheredynamic lakes are found.

Sub-glacial Lake Environment and FaciesRevealed by Larsen B Ice ShelfDisintegration

Domack, Eugene Domack Eugene W; LeventerAmy; Rebesco Michele; Zgur Fabrizio;Brachfeld Stefanie A; Willmott Veronica;Halverson Galen P; Lavoie Caroline E.W.Domack, V. Willmott, C. Lavoie, Geoscience,Hamilton College, Clinton, NY; A. Leventer,Geology, Colgate University, Hamilton , NY; M.Rebesco, F. Zgur, Geofisica, Istituto Nazionaledi Oceanografia e di Geofisica Sperimentale(OGS), Sgnonico, ITALY; S.A. Brachfeld,Department of Geology, Montclair StateUniversity, Montclair, NJ; G.P. Halverson,Geology & Geophysics, The University ofAdelaide, Adelaide, South Australia,AUSTRALIA

The identification of subglacial lake sedimentsin ancient sequences is difficult to inferbecause subglacial lakes are the mostinaccessible deposystems for direct study ofprocess/product. To date the best availableanalogs are recent deep basins previouslycovered by the Larsen Ice Shelf system. Thecollapse of the Larsen-B Ice Shelf (LIS-B) andsubsequent rapid retreat of the Crane Glacierresulted in the formation of 15 km long fjord.The fjord trough is characterized by thepresence of three deep (>1000 m) and narrow(~1 km wide) basins. The basins areseparated by more elevated thresholds whosemorphology of elongated ridges and gutterssub-parallel to the axis of the fjord, isinterpreted as sub-glacial bed forms thatformed as the result of deposition of subglacialtill--beneath grounded ice. At the time of icegrounding, the basins existed as sub-glaciallakes. More than 40 m of horizontally stratifiedsediments are present within the deepest ofthe fjord basins. A kasten core of theuppermost 2.6 meters of sediment documentsthat recent sediments were deposited at a highrate (2 m/year) under open marine conditionsfollowing ice shelf retreat. The underlyingsediments likely were deposited in a sub-glacial lake setting; these sediments will bejumbo piston cored during cruise NBP10-01,during January-February 2010. Our workinghypotheses are that these sediments weredeposited (a) over the past ~ 30 years,

roughly since the onset of the decrease in theextent of the ice shelves in the region, or (b) arelatively steady, less extraordinarysedimentation rate within the quietenvironment of the sub-glacial lake. Thissecond interpretation may be supported by thehigh penetration shown by the sub-bottomacoustic profiles, down to the reflector at thebase of the 40-m thick layered fill. Thisobservation suggests the presence of arelatively fine grain-size, without appreciablevariations. In fact, episodes of coarse grainsize and/or acoustic fancies changes would beexpected in case major environmentalchanges. If we assume that the LGM was thelast time the ice was grounded within the fjord,the average sedimentation rate of the layeredfill would be of the order of few hundredcm/kyr a rate comparable to that of the PalmerDeep record on the opposite side of theAntarctic Peninsula. What is unique here is thatthis record would have been deposited in asub-glacial lake environment, since the icecover is known to have persisted in the areafor the entire Holocene. Moreover, thisextraordinary record would have also recordedthe abrupt transition to an open sea setting,with accelerated ice discharge following thebreak-up of the ice shelf. This sedimentaryrecord, and other similar, yet unsampledsedimentary sequences, provide a windowthrough which to decipher the dynamics of thesub-ice processes that result in and accompanythe loss of ice mass and its transfer to oceanicsystems.

Environmental Protection andStewardship of Subglacial AquaticEnvironments

Doran, Peter Doran Peter T; Vincent WarwickF P.T. Doran, Earth and EnvironmentalSciences, University of Illinois at Chicago,Chicago, IL; W.F. Vincent, Centre for NorthernStudies (CEN) & Dept de Biologie, LavalUniversity, Quebec, Quebec, CANADA

Antarctic subglacial aquatic environments havebeen documented for some time using remotesensing (geophysical) techniques, but onlyvery recently have there been plans devisedand implemented to enter and study theseenvironments directly. The long lead up to thesampling of these lakes is largely related to thelogistical difficulty of doing so, but also due tothe cautious approach warranted by thepristine nature of the environments, and theiralmost completely unknown capacity to sustainviable ecosystems. It is because of the needfor caution that the U.S. National ScienceFoundation requested guidance from the


National Academies to address standards ofresponsible exploration of subglacial aquaticenvironments. In response, the NationalResearch Council of the National Academiescreated the Committee on the Principles ofEnvironmental and Scientific Stewardship forthe Exploration and Study of SubglacialEnvironments. The committee made 13recommendations towards this end. The NRCstudy and recommendations will be reviewed inthis talk as well as an assessment of thestudy’s impact, including ongoing internationaldevelopment of a Code of Conduct to exploreand protect Antarctic subglacial waters.

Evidence for Microbial Metabolism at -15°C in an Antarctic SubglacialEnvironment

Doyle, Shawn Doyle Shawn M; AchbergerAmanda M; Montross Scott N; Brox Timothy;Suematsu Kohei; Skidmore Mark L; ChristnerBrent Craig S.M. Doyle, A.M. Achberger, B.C.Christner, Biological Sciences, Louisiana StateUniversity, Baton Rouge, LA; S.N. Montross, T.Brox, M.L. Skidmore, Earth Sciences, MontanaState University, Bozeman, MT; K. Suematsu,The Institute of Low Temperature Science,Hokkaido University, Sapporo, JAPAN;Analysis of the gases entrapped in sediment-rich basal ice from the Taylor Glacier, anoutflow glacier of the East Antarctic Ice Sheet,have revealed anomalies with respect to theconcentrations of CO2 and CH4 (>1000 timesatmospheric) and O2 (<1

The Whillans Ice Stream SubglacialAccess Research Drilling (WISSARD)Project: an Integrated Study of Marine IceSheet Stability and Subglacial LifeHabitats in West Antarctica

Fricker, Helen Fricker Helen Amanda; TulaczykSlawek M; Powell Ross D; Priscu John C;Anandakrishnan Sridhar; Christner BrentCraig; Fisher Andrew T; Holland David M;Jacobel Robert W; Mikucki Jill; MitchellAndrew Charles; Scherer Reed P;Severinghaus Jeff H.A. Fricker, J.P.Severinghaus, IGPP, Scripps Institution ofOceanography, La Jolla, CA; S.M. Tulaczyk,A.T. Fisher, , University of California, SantaCruz, Santa Cruz, CA; R.D. Powell, R.P.Scherer, , Northern Illinois University, DeKalb,IL; S. Anandakrishnan, , Pennsylvania StateUniversity, State College, PA; R.W. Jacobel, ,St. Olaf College, Northfield, MN; J.C. Priscu,A.C. Mitchell, , Montana State, Bozeman, MT;B.C. Christner, , Louisiana State, Baton Rouge,LA; J. Mikucki, , Dartmouth College, Hanover,

NH; D.M. Holland, , New York State University,New York, NY

WISSARD is a 6-year NSF-funded projectwhich involves 13 PIs at 9 institutions that willuse an interdisciplinary science approach tostudy the subglacial environment of theWhillans Ice Stream in West Antarctica. It issplit into three sub-projects: LISSARD (Lakeand Ice Stream Subglacial Access ResearchDrilling); RAGES (Robotic Access to Grounding-zones for Exploration and Science); and GBASE(GeomicroBiology of Antarctic SubglacialEnvironments). LISSARD focuses oninvestigating the role of active subglacial lakesin controlling temporal variability of ice streamdynamics and mass balance. RAGESconcentrates on stability of ice streamgrounding zones which may be perturbed byincreased thermal ocean forcing,filling/draining cycles of subglacial lakes,and/or internal ice stream dynamics. GBASEaddresses metabolic and phylogeneticdiversity, and associated biogeochemicaltransformations in subglacial lake andgrounding zone environments. These sub-projects are connected scientifically throughcommon interest in coupled fluxes of ice,subglacial sediments, nutrients and water, aswell as by the common need to characterizeand quantify physical, chemical and biologicalprocesses operating subglacially. The projectwill focus on the lower Whillans Ice Stream,where three hydrologically connectedsubglacial environments that lie within closegeographical proximity can be accessed: asubglacial lake (Lake Whillans); wet subglacialsediments including the grounding-zonewedge; and the sub-ice-shelf cavity. Directsampling will yield seminal information on theglaciological, geological and microbialdynamics of these environments and test theoverarching hypothesis that active hydrologicalsystems connect various subglacialenvironments and exert major control on icesheet dynamics, geochemistry, metabolic andphylogenetic diversity, and biogeochemicaltransformations of major nutrients withinglacial environments. We will present anoverview of the hypotheses, time-line,significance as well as the challenges that weforesee.http://www.wissard.org

Synthesising Multiple Remote SensingTechniques for Analysing SubglacialHydrologic Systems: Application onMacAyeal Ice Stream, West Antarctica

Fricker, Helen Fricker Helen Amanda;Scambos Theodore A; Carter Sasha P; DavisCurt H; Haran Terence M; Joughin Ian R;

MacAyeal Douglas Reed H.A. Fricker, S.P.Carter, IGPP, Scripps Institution ofOceanography, La Jolla, CA; T.A. Scambos,T.M. Haran, , National Snow and Ice DataCenter, Boulder, CO; I.R. Joughin, , Universityof Washington, Seattle, WA; C.H. Davis, ,University of Missouri-Columbia, Columbia,MO; D.R. MacAyeal, , University of Chicago,Chicago, IL

We present an analysis of the active hydrologicsystem of MacAyeal Ice Stream (MacIS), WestAntarctica from a synthesis of multiple remotesensing techniques: satellite laser and radaraltimetry; satellite image differencing; andhydrostatic hydropotential mapping (using asatellite-derived digital elevation model (DEM)and a bedrock DEM from airborne-radio echosounding). Combining these techniquesaugments the information provided by eachone individually, and allows us to develop aprotocol for studying subglacial hydrologicsystems in a holistic manner. Our studyreveals five large active subglacial lakes underMacIS, the largest of which undergoes volumechanges of at least 1.0 km3. We discuss thehydrologic properties of this system andpresent evidence for links between the lakes.At least three of the lakes are co-located withsticky spots. We also find evidence for surfaceelevation changes due to ice dynamic effects(not just water movement) caused by changesin basal resistance. We show that satelliteradar altimetry is of limited use for monitoringlake activity on fast-flowing ice streams withsurfaces that undulate on ~10 km) lengthscales. Finally, to assess whether there is alink between lake flooding and ice dynamics,we examined the largest lake for flow speedchanges during fill and drain cycles withseveral ASTER images. Ice velocity mappingusing ASTER image pairs spanning periodswhen the lake is drained show flow speeds upto 40 m/yr slower than when the lake is filled.We infer that flow speed decreased as a resultof increased basal resistance (from zero tonon-zero as the ice encountered the basalsediments). The scale of the slowdown issimilar to modeled results on nearby icestreams.

UW-Wisconsin (ICDS) WISSARD DrillingProgram: Environmental Stewardship,Engineering, and Scientific Objectives

Gerasimoff, Michael Gerasimoff Michael M.Gerasimoff, Space Science and EngineeringCenter, University of Wisconsin, Madison,Madison , WI

WISSARD is an ambitious sub-glacialexploration program encompassing thedisparate needs of the LISSARD, GBASE, andRAGES projects. Accessing the sub-glacialenvironment requires hot-water-drilled boresranging from a about 15 to 50 cm diameter,dependent on science requirements,anticipated occupation period, and resultingallowance for freeze-back. Calculationsindicate 1 to 3 megawatts is required fordrilling and related processes. LISSARD andGBASE projects require smaller bores andlower heat flux, but environmental stewardshipand the scientific objectives impose challengingaseptic requirements. The RAGES projectdeploys a submarine ROV via the largestbores, requiring the largest heat flux.Maintaining the bore for periods that mightexceed 300 hours by recirculating salt-contaminated water presents engineering andoperational challenges. We present ourcurrent design embodiment encompassingdrilling, filtration and related systemsaddressing critical engineering, environmentalstewardship, scientific deployment and otherissues. www.wissard.org

Exploring Former Subglacial HodgsonLake, Antarctica: Geomorphology,Limnology and Paleolimnology

Hodgson, Dominic Hodgson Dominic; RobertsSteve; Bentley Michael; Smith James;Verleyen Elie; Vyverman Wim; Leng Melanie;Sanderson David; Johnson Joanne; HodsonAndy D. Hodgson, S. Roberts, J. Smith, J.Johnson, , British Antarctic Survey, Cambridge,UNITED KINGDOM; M. Bentley, Dept.Geography, University of Durham, Durham,UNITED KINGDOM; E. Verleyen, W. Vyverman,Dept. Biology, University of Ghent, Ghent,BELGIUM; M. Leng, Isotope Geoscience Lab,NERC , Keyworth, UNITED KINGDOM; D.Sanderson, , SUERC, East Kilbride, UNITEDKINGDOM; A. Hodson, Dept. Geography,University of Sheffield, Sheffield, UNITEDKINGDOM

Direct exploration of subglacial lakes burieddeep under the Antarctic Ice Sheet has yet tobe achieved. However, at retreating margins ofthe ice sheet, there are a number of locationswhere former subglacial lakes are emergingfrom under the ice but remain perennially icecovered. We present a study of Hodgson Lake(72° 00.549’S, 068° 27.708’ W), including itsgeomorphology, limnology andpalaeolimnology. Thick perennial ice coverpersists over the lake today and the watershave remained isolated from the atmosphere.Nutrient concentrations within the ranges of


those found in the accreted lake ice of LakeVostok. TOC and DOC are present, but at lowerconcentrations than in continental rain. Noorganisms were detected using lightmicroscopy. Increases in SO4 and cationconcentrations at depth and declines in O2provide some evidence for sulphide oxidationand very minor bacterial demand upon O2.However, in general the chemical markers oflife in the water are inconclusive. Thepalaeolimnology of the lake was studied usinga 3.8 m sediment core dated using acombination of radiocarbon, OSL, and relativepalaeomagnetic intensity dating. Fourstratigraphic zones (A–D) were identified.Zones A–C were deposited between MarineIsotope Stages 5–2 and zone A during Stage 1.The palaeolimnological record tracks changesin the subglacial depositional environmentlinked principally to changing glacier dynamicsand mass transport and indirectly to climatechange. There is no evidence of overridingglaciers being in contact with the bedreworking the stratigraphy or removing thissediment. This suggests that the lake existedin a subglacial cavity beneath overriding LGMice. In zone D there is a transition to finergrained sediments characteristic of lowerenergy delivery coupled with a minor increasein the organic content. Evidence of biologicalactivity is sparse. TOC varies from 0.2 to 0.6

Scanning Detection of MultiscaleSignificant Trend-Changes in Ice-coreRecords

Jiang, Jianmin Jiang Jianmin; Gu Xiangqian J.Jiang, , Training Centre of ChinaMeteorological Administration, Beijing, Beijing,CHINA; X. Gu, , Chinese Academy ofMeteorological Sciences, Beijing, Beijing,CHINA

Abstract The author has developed fourscanning algorithms for detecting coherency ofmultiscale significant changes in subseriesmeans, variances and trends between two timeseries and the subseries correlation changesrespectively (Jiang, 2009). Here we presentone of the four, the scanning F-test fordetecting multiscale change-points in subseiestrends (regressions to time), specially fordrilling cores which are recorded in unequalintervals. Scanning detections of changes insubseries means and variances in sedimentcores were demonstrated by Jiang etal.(2007). These algorithms feature graftingthe wavelet technique onto the classicalstatistic test and giving statistic criteria at aconfidence level, as well as automatic andobjective detection on various time scales.

As an example, the algorithm was employed totwo series of average values of δ18O and ofδ15N in trapped gases of the Vostok ice core(http://nsidc.org/data/nsidc-0107.html). Theprimary results in contour patterns (Fig. 1)feature generally that the δ18O (Fig.1a) have21 significant change-points, which is morefrequent than that in the δ15N with 15 change-points (Fig.1b), the coherency (Fig.1c)between Fig.1a and b appears mainly positivebefore 142.7 Ky BP while negative after thenon longer time-scales. Key references: Jiang,J., X. Gu, and J. Ju, “Significant changes insubseries means and variances in an 8000-year precipitation reconstruction from treerings in the southwestern USA”, Ann.Geophys., 2007, 25: p1519–1530, www.ann-geophys.net/25/1519/2007/ Jiang, J.:“Scanning detections of multi-scale significantchange-points in subseries means, variances,trends and correlations”, in < 2009 SixthInternational Conference on Fuzzy Systemsand Knowledge Discovery>, V5:609-613, IEEEPress.

Low-frequency Radar Profiles of theRecovery Lakes

Kohler, Jack Langley Kirsty; Kohler Jack K.Langley, J. Kohler, , Norwegian Polar Institute,Tromso, NORWAY

Four new large sub-glacial lakes (SGLs) wereidentified recently at the head of the RecoveryGlacier ice stream in East Antarctica, usingMODIS imagery and ICESat elevation data. Thesurface areas of these lakes would make themamong the largest SGLs in Antarctica, secondonly to Lake Vostok. Beyond their size, theRecovery Lakes (RL) are compellingly locatedjust at the onset of fast flow in the RecoveryIce Stream, suggesting a linkage between thepresence of water at the bed and the initiationof rapid ice flow In January 2009, theNorwegian-US IPY traverse passed over the RLarea, en route from South Pole to Norway’sTroll Station (Fig.1). Here we present lowfrequency radar data collected over the RLsduring the traverse, and examine the evidencefor their existence based on the reflectivity ofthe basal reflector and on the relative flatnessof the basal interface.

Potential Proxies Held In SedimentInclusions From Ice Cores Of The VostokStation Borehole

Leitchenkov, German Leitchenkov German L;Belyatsky Boris; Bulat Sergey; LipenkovVladimir G.L. Leitchenkov, B. Belyatsky,Antarctic Geoscience, Institute for Geology and

Mineral Resources of the World Ocean, St.-Petersburg, RUSSIAN FEDERATION; S. Bulat, ,Petersburg Nuclear Physics Institute, St.-Petersburg, RUSSIAN FEDERATION; V.Lipenkov, , Arctic and Antarctic ResearchInstitute, St.-Petersburg, RUSSIANFEDERATION

The borehole at the Vostok Station has beendrilled into an accreted ice layer originatingfrom refreezing of the lake water. This layercontains random sediment inclusions, nine ofwhich have been studied using state-of the-artanalytical techniques. Six inclusions comprisesoft aggregates mainly consisting of clay-micaminerals and micron-sized quartz grains whilethree others contains quite large rock clasts.Electron microscopy of soft inclusions extractedfrom depth of 3559 m have revealed small(several micron-sized) particles of sulfideminerals (molybdenite, sphalerite and pyrite).Two principal ways of their origin could besuggested: i) disintegration of ancientmetamorphic rocks by glacial erosion anddeposition over the western lake shore(exaration) and ii) recent endogenousprocesses in a depth. Pyrite shows typicalcubic-shaped crystalline morphology which isunlikely to be preserved in the course of iceexaration as this mineral is quite soft.Moreover, under highly oxidative conditionsexpected in the lake due to oxygenaccumulation upon ice melting pyrite particlesshould not be resistant but rather replaced byiron oxide followed by iron oxihydroxide as afinal product. Molybdenite and sphalerite weredetected in the assemblage with pyrite andprovide an extra support for in situ formationof mineral assemblages by recent endogenousactivity pointing out their rapid trap inaccretion ice. Such endogenous activity in adepth provides evidence for hydrothermalactivity in the Lake Vostok (additionally tosome other arguments). Rock clasts from twoinclusions (3582 and 3607 m) consists ofpoorly-rounded quartz and minor amounts ofaccessory minerals and is classified asquartzose siltstone. 21 grains of zircon and 5grains of monazites (from 2-5 to 30-40 μm insize) have been identified in the siltstone anddated by SIMS SHRIMP-II. Two age clustershave been recognized for these detrital grains,in the ranges 0.8−1.2 Ga and 1.6−1.8 Ga. Thelargest inclusion (3608 m) contains 13 poorly-rounded rock clasts (ranging in size from 0.5to 3.5 mm) which were identified assandstones and siltstones. Most of clasts isdominated by quartz; one clast consistscompletely of apatite; and two clasts haveconsiderable quantity of feldspar. 11 zirconsand 11 monazites were detected in these rocks

and next step of study will include additionalSHRIMP analysis to define ages of this U-bearing minerals. The compositions of the rockclasts suggest that the bedrock situated to thewest of Lake Vostok is sedimentary. The agedata on the detrital accessory minerals(studied so far in two inclusions) allow us tospeculate that the provenance of thesesedimentary rocks − the GamburtsevMountains and Vostok Subglacial Highlands, ismainly represented by Paleoproterozoic andMesoproterozoic- Neoproterozoic crustalprovinces.

Modeling the Spatial Variation Of EnglacialRadar Attenuation: Application To TheVostok Flowline And Implications For TheDetection Of Subglacial Lakes

MacGregor, Joseph MacGregor Joseph A;Matsuoka Kenichi; Winebrenner Dale P;Waddington Edwin D; Pattyn Frank J.A.MacGregor, Institute for Geophysics,University of Texas, Austin, TX; K. Matsuoka, ,Norwegian Polar Institute, Tromso, NORWAY;K. Matsuoka, D.P. Winebrenner, E.D.Waddington, Dept. of Earth and SpaceSciences, University of Washington, Seattle,WA; D.P. Winebrenner, Polar Science Center,University of Washington, Seattle, WA; F.Pattyn, Dept. des Sciences de la Terre et del'Environnement, Universite Libre de Bruxelles,Brussels, BELGIUM

Knowledge of the spatial variation of englacialradar-attenuation rates is poor, but it isneeded to accurately infer englacial and basalproperties from ice-penetrating radar data,including the location of subglacial lakes.Attenuation rates depend on the spatialvariation of temperature and soluble impurityconcentrations. Because temperature andimpurity concentrations are measured only atthe surface or in boreholes or ice cores, modelsof their spatial variation are required to predictattenuation rates in ice sheets. Here weevaluate several models of the spatial variationof attenuation rates and present an example oftheir application along a flowline that crossesover Lake Vostok, East Antarctica, and throughthe Vostok ice core. The first and simplestpossible model is a uniform, depth-averagedattenuation rate everywhere along theflowline; the next simplest model uses spatiallyvarying temperatures from athermomechanical ice-sheet model, butassumes uniform impurity concentrations.Subsequent models also use radar-layerdepths and/or velocities from the ice-sheetmodel to extend Vostok impurity-concentrationdata along the flowline and predict their spatial


variation. We find that models that includespatially varying temperatures predict largedifferences in roundtrip attenuation (> 10 dB)compared to the model that assumes auniform attenuation rate; these differences arelarge enough to confound subglacial lakedetection. Models that include the spatialvariation of impurity concentrations introducesmaller (< 5 dB) changes to the roundtripattenuation. This work shows that anattenuation-rate model tied to an ice-core sitecan be satisfactorily extended spatially usingradar-layer depths and a temperature model.The application of such models to ice-penetrating radar datasets will permit morereliable detection of subglacial lakes,particularly in regions with large ice-thicknesschanges.

The Geomorphic Signature Of SubglacialFloods

Marchant, David Marchant David R; SugdenDavid D.R. Marchant, Earth Sciences, BostonUniversity, Boston, MA; D. Sugden, School ofGeoSciences, The University of Edinburgh,Edinburgh, Scotland, UNITED KINGDOM

There is geomorphic evidence in theTransantarctic Mountains supporting the ideaof catastrophic drainage of, and erosion from,subglacial lakes in East Antarctica; theerosional features include vast tracts ofscoured-bedrock terrain, bedrock-channelsystems, and scabland topography. Some ofthe meltwater tracts extend for over 50 km inlength, and may be linked to extensiveoffshore channels. Our aim is to usegeomorphology to help understand thedynamics of subglacial meltwater flow and itsrole in glacial erosion and deposition. Thebedforms in the Dry Valleys area give aninsight into the locations, magnitude, andfrequency of subglacial outbursts in a largearea that was formerly the bed of an expandedEast Antarctic ice sheet. Our mapping resultsshow that the subglacial channels areanastomosing, with potholes at junctions andreverse gradients in longitudinal profiles.Flood magnitudes are inferred to be on theorder of the Lake Missoula floods (e.g., hugedischarges associated with recession of theLaurentide ice sheet). Modeling studies pointto a source for meltwater in interior EastAntarctica, with the possibility that significantwater bodies were temporarily held in place bya transient ice dam (cold-based ice) on theinland flanks of the Transantarctic Mountains.The latest flood to cross the Dry Valleys regionlikely dates to middle Miocene time. Youngerfloods may have occurred, but the meltwater

most probably passed through over-deepenedtroughs (not yet fully developed at the time ofthe Miocene floods) that today lie beneathmodern outlet glaciers. One unknown is thefate of sediment eroded by these subglacialfloods; sedimentary deposits, if they existed,have not been identified in exposed areas ofthe continent. One possibility is that much ofthe debris may ultimately have frozen onto thebasal ice and was carried out to the continentalshelf. A second unknown is the ecological andclimate impact of large volumes of freshwaterdischarging into the Ross Embayment,particularly during the mid-Miocene whenablation (via melting) of the ice surface mayhave preconditioned the Southern Ocean toabrupt change.

Detecting Wet Ice-sheet Beds AcrossAntarctica Using Radar: A FeasibilityAssessment Using Three-dimensionalTemperature And Radar AttenuationModels

Matsuoka, Kenichi Matsuoka Kenichi; PattynFrank; MacGregor Joseph A K. Matsuoka,Earth and Space Sciences, University ofWashington, Seattle, WA; K. Matsuoka, ,Norwegian Polar Institute, Tromso, Troms,NORWAY; F. Pattyn, , Université Libre deBruxelles, Brussels, BELGIUM; J.A. MacGregor,University of Texas at Austin, Austin, TX

Diagnosing subglacial conditions usingobserved radar power returned from the bed(bed-echo intensities) requires a correction forthe dielectric attenuation through the iceoverburden. This attenuation depends on icetemperature and chemistry, so it is spatiallyvarying. The difference between the specularreflectivities of wet and dry beds is up to 25dB. A depth-averaged attenuation-ratedifference of ~4 dB/km (one way) in 3-km-thick ice can therefore easily confoundinterpretations of subglacial conditions. Arecent estimate of the spatial variation ofattenuation rates in central West Antarcticashows that they vary by up to 5 dB/km withina ~120-km by ~120-km area. Theseobservations motivate a reassessment of theconventional belief that brighter and dimmerbeds can be simply interpreted as wetter anddrier beds, respectively. We estimated thethree-dimensional attenuation-rate field for theentire Antarctic ice sheet using an existingtemperature-dependent attenuation-ratemodel and temperatures from athermomechanical model. For these initialcalculations, we ignore spatial variations inchemistry, since previous attenuation-rateestimates at ice-core sites showed that ice

chemistry is of secondary importance. Tomitigate uncertainties related to the poorlyknown spatial variation in geothermal flux weevaluated the robustness of our results usingseveral geothermal-flux models that werecalibrated using borehole-temperature profilesand the locations of known subglacial lakes andice streams, where the bed is presumed to bewet. Bed reflectivity is assigned based on thetemperature model and the bed-returnedpower is predicted. We discuss properties ofdepth-averaged attenuation across Antarcticaand potential pitfalls related to the diagnosis ofsubglacial conditions using radar.

Subglacial Lake Regimes For DifferentLake Categories

Mayer, Christoph Mayer Christoph; ThomaMalte; Grosfeld Klaus; Siegert Martin John C.Mayer, M. Thoma, Commission for Glaciology,Bavarian Academy of Sciences and Humanities,Munich, GERMANY; M. Thoma, K. Grosfeld,Climate Sciences, Alfred Wegener Institute forPolar and Marine Research, Bremerhaven,GERMANY; M.J. Siegert, School ofGeoSciences, University of Edinburgh,Edinburgh, UNITED KINGDOM

Since the first discovery of subglacial lakes inthe late 1960s the knowledge about subglacialwater bodies has changed dramatically. Firstonly a small number of lakes (17) wereidentified in the centre of the Antarctic IceSheet, including Lake Vostok. The developmentof ideas concerning internal hydrologicalconditions and mass exchange with the icesheet took a long time to develop. Since themid 1990s about 280 subglacial lakes havebeen discovered underneath the ice sheet,ranging from some kilometres to about 250 kmin dimension, being covered by an ice layerfrom less than 2 km up to more than 4 kmthick. The lakes are located at severalcharacteristic locations across Antarctica. Alsothe interaction between lakes and thesurrounding ice sheet is highly variable rangingfrom likely closed systems with very little massexchange to water bodies with extensive, rapidand possibly periodical water discharges. Herewe provide a comprehensive summary of theprincipal conditions regarding the internalphysical conditions influencing subglacial lakes,their mass exchange with the ice sheet above,and the consequences for both, lake and icedynamics. Subglacial lakes occur in specificlocations defined by subglacial topography andthe related effective hydrostatic pressuredistribution, ice dynamics and geothermalconditions. The lakes physical conditionsdepend on these parameters, which in return

determine the interaction level of the lake. Forexample, lakes at the head of fast flowing icestreams could play a much stronger role interms of ice-sheet dynamics than lakes ininner-continental basins. Also ice thicknessplays an important role in the hydrodynamicregime of subglacial lakes. The generation ofdifferent lake categories, in relation to theirspecific settings, allows us to describe theoverall physical conditions and the potentialinteraction level of subglacial lakes with theirenvironment.

Blood Falls, Antarctica: Insights IntoSubglacial Microbial Energetics

Mikucki, Jill Mikucki Jill; Priscu John C J.Mikucki, Earth Sciences and EnvironmentalStudies, Dartmouth College, Hanover, NH; J.C.Priscu, Land Resources and EnvironmentalSciences, Montana State University, Bozeman,MT

The subglacial environment is one of the mostdifficult portions of the cryosphere to accessand only recently, in collaboration with large-scale drilling projects, are ecologists beginningto explore the more remote reaches of thesubglacial biome. The subglacial environmentbeneath the Taylor Glacier, a cold-based polarglacier in the McMurdo Dry Valleys, Antarcticasupports a metabolically and geneticallydiverse biosphere that can be used as a modelfor other subglacial systems. The TaylorGlacier’s subglacial discharge, Blood Falls, is abrine remnant from Pliocene marine watersthat is inhabited by cryo- and halotolerantorganisms that are related to marine species.Surface meltwater does not penetrate to thebase of the Taylor Glacier and no oxygen isdetected in outflow waters suggesting thatanoxia is an important regulator of microbialenergetics. Limited organic carbon supply fromthe absence of contemporary photosynthesisappears to have influenced the choice ofmetabolic pathways employed by thissubglacial community. Molecular data andbiogeochemical measurements indicate thatchemoautotrophic activity is present andsuggests that subglacial systems can besustained independent of allochthonous fixedcarbon inputs. Isotopic measurements of iron,sulfur and oxygen have shown thatchemoorganotrophic or heterotrophic growthon ancient marine organics coupled to Fe(III)or sulfate respiration drives a catalytic sulfurcycle resulting in a subglacial system that isnet iron reducing. As we move forward withthe exploration of subglacial systems, existingmodels, such as the Taylor Glacier system wedescribe here, will provide important insight


into ecosystem structure and function and willprovide relevant tools for the examination ofthe geomicrobiology of other subglacialenvironments.

Probe Technologies for The DirectMeasurement and Sampling of SubglacialLake Ellsworth

Mowlem, Matthew Mowlem Matthew Charles;Floquet Cedric; Tsalogolou Maria-Nefeli;Waugh Edward; Fowler Lee; Saw Kevin M.C.Mowlem, C. Floquet, M. Tsalogolou, E. Waugh,L. Fowler, K. Saw, Underwater SystemsLaboratory, National Oceanography CentreSouthampton, Southampton, hampshire,UNITED KINGDOM

The direct measurement & sampling ofSubglacial Lake Ellsworth will be amultidisciplinary investigation of life in extremeenvironments and West Antarctic ice sheethistory. The project’s aims are : (1) todetermine whether, and in what form,microbial life exists in Antarctic subglaciallakes, and (2) to reveal the post-Pliocenehistory of the West Antarctic Ice Sheet. Anextensive logistics and equipment developmentprogramme will deliver the necessaryresources to the location of the lake. This willinclude novel hot water drill technology (forlake access through ~3.4km of ice), a bespokeprobe (to make measurement with sensors andto collect water and sediment samples), agravity corer (to acquire a longer sedimentcore) and a thermistor string for long termmonitoring of the lake. This paper details thedesign development of the probe system. Thisincludes the instrumentation package, watersamplers and a mini gravity corer mounted onthe front of the probe. Supporting equipmentrequired at the drill site to deploy and operatethe probe is also described. The project aimsto complete the experiment in a clean andenvironmentally responsible manner in linewith principles set out by SCAR. The projectwill apply current knowledge of microbiologicaltransfer and best practice in protection ofpristine environments. The design philosophyof the probe and systems is to minimise costand enhance reliability. To achieve this, thenumber and complexity of elements is kept toa minimum, and proven commercial off-the-shelf (COTS) technology is used whereverpossible, limiting the risk and cost of bespokesystem development. The probe is heavilynegatively buoyant, is tethered to the surfaceand has only simple manoeuvrability (depthcontrol via tether and limited rotation). Theprobe is ~3.5m in length and 20cm in diameterand consist of two air-filled pressure cases

separated by three carousels of water samplersall attached to a central flexible core that isattached to the tether. The bottom pressurecase houses the majority of the instrumentpackage and is tipped with a short gravity coresediment sampler (increasing total length to~4m). The upper pressure case contains thepower and communications link to the tether.Scientific return is ensured by the combineduse of instrumentation returning real-timedata, and acquisition of water and sedimentsamples for post-retrieval analyses. Thisprovides redundancy, and enables informeddeployment of the sampler systems. Anonboard microprocessor and data loggerenable continued operation (e.g. sampling atpredetermined intervals) and archiving ofinstrument data in case of communicationsfailure. Power will be supplied both through thetether and by onboard batteries, the latterbeing sufficient to complete the mission butwith limited video footage. Probe-to-surfacecommunications (two-way) will be via anoptical link and backup wire modem usingCOTS technology used in several deepremotely-operated vehicles. The deployment inthe field is scheduled for December 2012.

Antarctic Subglacial Lake Discharges

Pattyn, Frank Pattyn Frank F. Pattyn,Laboratoire de Glaciologie, Universite Libre deBruxelles, Brussels, BELGIUM

Antarctic subglacial lakes were long timesupposed to be relatively closed and stableenvironments with long residence times andslow circulations. This view has recently beenchallenged with evidence of active subglaciallake discharge underneath the Antarctic icesheet. Satellite altimetry observationswitnessed rapid changes in surface elevationacross subglacial lakes over periods rangingfrom several months to more than a year,which were interpreted as subglacial lakedischarge and subsequent lake filling, andwhich seem to be a common and widespreadfeature. Although less impressive, suchdischarges are comparable to jökulhlaups andcan be modelled that way using the Nye–Röthlisberger theory. Subglacial water flow isdriven by the hydraulic potential gradient,which also controls when water will be drivenout of a subglacial cavity. Considering the iceat the base of the ice sheet at pressure meltingpoint, subglacial conduits are sustainable overperiods of more than a year and over distancesof several hundreds of kilometers.Furthermore, the theory is useful to predict thehydrograph defining lake filling and discharge.In addition, coupling of an ice sheet model to a


subglacial lake system demonstrated thatsmall changes in surface slope are sufficient tostart and sustain episodic subglacial drainageevents on decadal time scales. Therefore, lakedischarge may well be a common feature ofthe subglacial hydrological system, influencingthe behavior of large ice sheets, especiallywhen subglacial lakes are perched at or nearthe onset of large outlet glaciers and icestreams. While most of the observed dischargeevents are relatively small (1E1-1E2 m^3/s),evidence for larger subglacial discharges isfound in ice free areas bordering Antarctica,and witnessing subglacial floods of more than1E6 m^3/s that occurred between 14.4 and12.4 Ma ago.

The Search for Life in Former SubglacialLake Hodgson, Antarctica

Pearce, Alan Pearce David Anthony; HodgsonDominic; Cockell Charles D.A. Pearce, D.Hodgson, , British Antarctic Survey,Cambridge, UNITED KINGDOM; C. Cockell, ,Open University, Milton Keynes, UNITEDKINGDOM

Direct exploration of subglacial lakes inAntarctica has yet to be achieved. However, atthe retreating margins of the ice sheet, thereare a number of accessible locations whereformer subglacial lakes are emerging fromunder the ice, but which remain perennially icecovered. In this study, we describe the searchfor life in one such lake - Lake Hodgson(072°00.549'S, 068°27.708'W), which hasemerged from under more than 297-465 m ofglacial ice during the last few thousand years.Surface sediment taken 93.4m below the icesurface was investigated using a combinationof epifluorescence microscopy, scanningelectron microscopy, fluorescence in situhybridization, clone library construction andanalysis and direct culture. Results arepresented which include the presence orabsence of life, its characteristics and detectionlimits. The implications for future Antarcticsubglacial lake research are then discussed.

Seismic Imaging of the SubglacialPlumbing System

Peters, Leo Peters Leo E; AnandakrishnanSridhar L.E. Peters, S. Anandakrishnan,Geosciences, The Pennsylvania StateUniversity, University Park, PA

Subglacial water is necessary for fast flowingice as it can lubricate glacier beds and lowertheir basal shear stress. However, our currentability to image this hydrologic system is

limited to larger kilometer-scale subglaciallakes that are at least a meter thick. Wepresent the results of a series of syntheticseismic waveform modeling exercises whichsuggest the possibility of detecting centimeter-scale layers of water and dilatant till beneaththe kilometers-thick ice. These modelingresults demonstrate a means for obtaining abetter snapshot of the dynamics of the basalregime, as the subglacial plumbing system islikely important at the centimeter-scale. Ifseismic data are collected to capture thevarious reflections from the ice-bed interface,we can theoretically image the spatialdistribution of the subglacial water system,especially in regions surrounding knownsubglacial lakes, to better understand theconnectivity of basal hydrology beneathstreaming ice. With synthetic seismicwaveform modeling we predict the seismicreflectivity of all four potential seismicreflections for a basal layer, where we modeland determine the sensitivity of these seismicwaveforms to the thickness and materialproperties of the subglacial layer. Theamplitude variation with source-receiver offsetof these four basal reflections (purecompressional wave reflection, pure shearwave reflection, and the two converted wavereflections) 'reflect' the composition of thesubglacial bed, defined by its elastic properties(compressional wave velocity, shear wavevelocity, density). When a basal layer isgreater than a quarter seismic wavelengththick, the reflections from the top and bottomof that layer are discernible, allowing thethickness and elastic properties of the basallayer to be constrained from any one of thefour potential basal reflections. For a thinbasal layer, whose thickness is less than aquarter seismic wavelength, the reflectionsfrom the top and bottom of this layer interferewith each other. Both a pure wave reflectionand a converted wave reflection are needed toconstrain the thickness and elastic propertiesof the subglacial bed in this instance. Thestriking observation from the modeling resultsis that the converted wave reflections exhibit a180° phase shift in their waveforms when onlya centimeter of water or dilatant till is present,in comparision to no change in the seismicwaveform of a pure wave reflection. Thisphase shift demonstrates that converted wavereflections are quite sensitive to centimeter-scale layers of water and dilatant till beneaththe ice. Thin layers of water matter in termsof what 'moves' the ice, as only a thin film ofbasal water or dilatant till is needed toovercome the asperities at the bed that mayotherwise be inhibiting streaming ice flow. Ourmodeling results highlight the ability to capture


basal hydrology at the centimeter-scale,thereby providing a means of imaging thesubglacial plumbing system and highlighting itsoverall influence in ice dynamics.

New Helium Isotope Measurements in theAccreted Ice of the Subglacial Lake

Petit, Jean Robert Jean Baptiste Philippe; PetitJean Robert; Fourré Elise; Bulat Sergey;Alekhina Irina; Lipenkov Vladimir P. JeanBaptiste, E. Fourré, , Laboratoire des Sciencesdu Climat et de l’Environnement, CEA-Saclay,91191 Gif-sur-Yvette, , FRANCE; J. Petit, ,Laboratoire de Glaciologie et Geophysique del'Environnement CNRS-UJF, 38402, St Martind'Hères, FRANCE; S. Bulat, I. Alekhina, ,Petersburg Nuclear Physics Institute RAS,Leningrad Region, Gatchina, 188300 St.Petersburg , RUSSIAN FEDERATION; V.Lipenkov, , Arctic and Antarctic ResearchInstitute, 19939, St Petersburg, RUSSIANFEDERATION

Helium is a well-known tracer in earthsciences. It has two isotopes with contrastedproportions in Earth’s reservoirs: 3He isessentially primordial in origin whereas 4He isproduced by the radioactive decay of U and Th.When normalized to the atmospheric ratio (Ra= 1.38 10-6), typical 3He/4He ratios vary from<0.1 Ra in continental crust, to 8±1 Ra onaverage in the upper mantle, and up to ~ 40-50 Ra in products of plume-related oceanislands, such as Hawaii and Iceland, thought toderive from the lower mantle. Here, we reportnew helium isotope measurements in thedeepest ice drilled from the accreted ice massifof the subglacial Lake Vostok. Unlike mostgases, helium can be incorporated into thecrystal structure of ice during freezing, makinghelium isotopes in the accreted ice a valuablesource of information. Previous measurements(Jean-Baptiste et al., Nature 411, 2001) haveshown a pronounced difference in both thehelium concentration and isotope ratiobetween glacier ice and the refrozen lakewater, with atmospheric characteristics in theglacier ice and a factor of 3 enrichment and aclear radiogenic signature from underlying thecontinental bedrock in the accreted ice ([4He]= 33.9±2.6 nmol/kg, R = 0.25±0.04 Ra). Ournew data, from a depth range 3650.40 -3656.37 m display even higher heliumconcentrations ([4He] = 161±11 nmol/kg).The measured isotopic 3He/4He ratios (R =0.127±0.008 Ra) correspond to a mixturebetween atmospheric helium from the meltedglacier ice and crustal helium added to lakewaters with a radiogenic ratio R=0.007 Ratypical of the upper continental crust. This

increase of helium concentrations with depth inthe accreted ice implies the existence ofsustained helium gradient in the lake, placingnew constraints on water circulation andresidence time. It may also represent a steadydegassing from the surrounding bedrock fromboth a persistent tectonic activity, andradiogenic activity. In this respect ahydrothermal circulation in the deep faults islikely and may contribute to the survival of adeep biosphere.

Assessing Grounding Zones and Sub-Ice-Shelf Cavity Processes Using DirectSampling and Robotic Instrumentation

Powell, Ross Powell Ross D; Team RagesScience R.D. Powell, R.S. Team, Geology andEnvironmental Geosciences, Northern IllinoisUniv., DeKalb, IL

Grounding zones are seen as high prioritytargets to investigate because models indicatethese important areas strongly influence icesheet stability and hence rates of future sealevel rise. Based on our present limited dataand modeling efforts, grounding zones can beinfluenced by: (i) internal ice stream dynamics,(ii) rates of subglacial sediment (till) supply tothe grounding zone, (iii) increased melting bywarming ocean waters, and/or (iv)filling/draining cycles of subglacial lakes.However, we do not completely understand thefull influence or details of the importantprocesses in grounding zones. As one of threecomponents of a new project, WISSARD(Whillans Ice Stream Subglacial AccessResearch Drilling), RAGES (Robotic Access toGrounding-zones for Exploration and Science)research concentrates on the stability of thegrounding zone of the fast flowing Whillans IceStream (WIS). RAGES is a first comprehensiveattempt to investigate a sub-ice-shelf cavity inthese largely unexplored systems using acomplex array of newly designed andintegrated instrumentation and fieldoperational equipment. The WIS groundingzone has been the target of recent remotesensing and modeling studies (Anandakrishnanet al. 2007; Alley et al. 2007). These studieshave shown that a sedimentary grounding-zone wedge is accumulating with a consequentthickening of the WIS such that ice thicknessat the grounding line is greater than that of thehydrostatically-balanced floating ice of theRoss Ice Shelf. Thus the grounding line isbeing stabilized and it will arguably remain inthe same position until sea-level rise of at leastseveral meters overcomes the excess icethickness (Anandakrishnan et al. 2007).Alternatively, either ocean melt of grounding-

line ice or subglacial lake discharges mayenhance ice discharge, both of which increaseice stream flow to thin the grounded ice fasterthan at present. RAGES will collect data toassess this potentially critical situation.Further, Alley et al. (2007) have argued that ifthis condition occurs around all Antarcticgrounding lines, then recent Antarctic icevolume changes (after the rapid initial post-LGM retreat) cannot be attributed to sea-levelrise, but rather are due to direct warming.Assessing the conditions at WIS is therefore,prime for evaluating assertions thatsynchronous behavior of ice sheets onmillennial time-scales indicate ice-sheetteleconnections by either sea level or climaticforcing (cf. Alley et al. 2007; Naish et al. 2009;Pollard & DeConto 2009).http://wissard.org

Subglacial Lake Ellsworth: its History,Recent Field Campaigns and Plans for itsExploration

Ross, Neil Ross Neil; Rivera Andrés; SiegertMartin John N. Ross, M.J. Siegert, School ofGeoSciences, University of Edinburgh,Edinburgh, UNITED KINGDOM; A. Rivera, ,Centro de Estudios Científicos, Valdivia, CHILE

Direct access, measurement and sampling ofSubglacial Lake Ellsworth, West Antarctica isplanned for the 2012-13 Antarctic field season.This experiment aims to determine: i) thepresence, character and maintenance ofmicrobial life in Antarctic subglacial lakes; andii) the Quaternary history of the West AntarcticIce Sheet (WAIS). Lake Ellsworth, firstobserved in airborne radio-echo sounding dataacquired in 1978, is located in a long, deepsubglacial trough located near the head of thePine Island Glacier catchment ~30 km fromthe central WAIS divide. Recent geophysicalsurveys have characterised the lake, itssubglacial catchment and the thickness,structure and flow of the overlying ice sheet.Seismic reflection data have revealed the laketo be 156 m deep and underlain byunconsolidated sediments. This fact, itsphysiographical setting within a well-definedsteep topography and its location close to alogistics hub at Patriot Hills, makes the lakeideal for exploration. The seismic data havebeen used to define a preferred lake accesssite at the intersection between the centralaxis of the lake and the downstream-mostseismic profile. At this point the lake ischaracterised by: i) a relatively thin overlyingice column (~3.1 km); ii) a significantmeasured water depth (>145 m); iii) a lakefloor sediment thickness of >2 m; and iv) lowsedimentation rates (increasing the likelihood

for a long-term record of ice sheet history).The exploration project will build, test anddeploy all the equipment necessary tocomplete lake access, and direct measurementand sampling, in a clean and environmentallyresponsible manner. Hot-water drilling will beused to melt through the overlying ice. Thechemistry, micro-biology and physics of thelake environment will be investigated using acustom-built clean probe. Real-time dataacquisition during probe descent will provideflexibility for opportunistic sampling. After theprobe is recovered at the surface a corer willbe deployed for the acquisition of a lake floorsediment core. Detailed sedimentologicalanalysis of this core will be used to revealchanges in the lake environment, and the icesheet, through time. This project will be abenchmark exercise in the exploration ofAntarctica, and could make profound scientificdiscoveries regarding life in extremeenvironments and West Antarctic Ice Sheethistory.

A Sudden Outburst Flood Event BeneathCrane Glacier: Evidence, Causes, and IceDynamic Effects

Scambos, Theodore Scambos Theodore A;Berthier Etienne; Shuman Christopher A T.A.Scambos, National Snow and Ice DataCenter/CIRES, University of Colorado, Boulder,CO; C.A. Shuman, UMBC Goddard EarthScience and Technology Center, NASA GoddardSpace Flight Center, Greenbelt, MD; E.Berthier, OMP-LEGOS, Centre National de laRecherche Scienfifique, Toulouse, FRANCE

Recent studies have shown that sub-glaciallake activity can have a significant local effecton the flow speed of major outlet glaciers onthe great ice sheets (e.g., Byrd Glacier: L.Stearns et al., 2008 Nature Geoscience). Herewe present an additional case where a largesub-glacial drainage appears to have caused asignificant change in ice flow speed. The eventwas likely caused by the rapid elevationchanges on Crane Glacier. Crane Glacier in theAntarctic Peninsula has shown a remarkableincrease in speed (~8-fold) and decrease inelevation (~150 m) since the break-up of theLarsen B Ice Shelf in 2002. However, duringthe period November 2004 to November 2005,a portion of the lower glacier showed ansudden, localized (~2km diameter) increase inthe rate of lowering, exceeding 100 m/year fora few months. The glacier accelerated at agreater rate during and after this period (asdetermined by a series of satellite image pairsending with Formosat-2 images in 2008 and2009), and the surface character of the lower


glacier changed significantly to a highlyfractured serac field. Examination of the CraneGlacier fjord bathymetry by multi-beam sonarin regions now exposed due to ice shelf andglacier retreat shows a series of enclosed over-deepened basins. This suggests that a series ofsub-glacial lakes existed in the lower trunkprior to ice shelf disintegration. The region ofthe large Crane elevation change is still ice-covered and therefore unmapped forbathymetry, but may represent an additionallacusterine basin. Changing ice surface slopein the years before the sudden drawdown canbe inferred to have significantly changed thesub-glacial hydrologic pressure field. In theCrane Glacier case, acceleration duringdrainage may be driven by the large furtherincrease in along-flow surface slope caused bydrainage.

What Can Tiny Fossils Eeach Us AboutWAIS History and Subglacial Processes?

Scherer, Reed Scherer Reed P R.P. Scherer,Geology & Environmental Geosciences,Northern Illinois University, De Kalb, IL

As we launch a new phase of subglacial andsub-ice shelf exploration and sampling with theWISSARD project it seems a good time toreview the type of data regarding ice sheethistory and subglacial processes that can begleaned from microfossils recovered from thesubglacial and englacial environment.Sediments, including short sediment cores,were recovered from beneath the southernRoss Ice Shelf in the 1970s (Ross Ice ShelfProject Site J-9) and beneath Ross ice streamsin the 1990s (Upstream, Whillans and Kambice streams). Some sub-ice stream samplesinclude evidence of past retreat of the icesheet during the Pleistocene. Fossil diatoms(marine planktonic algae), with supportingevidence from cosmogenic-sourced 10Be in thesediments, provided evidence that open waterstretched across the West Antarctic interior atleast once (though possibly multiple times)during the last ca. 1 million years (Science,281, 82-85, 1998; GRL, 35, 2008).Unfortunately, a key hypothesis described byJohn Mercer in his famous “Threat of Disaster”paper (Nature, 271, 321-325, 1978) remainsequivocal: Did the WAIS collapse during thepenultimate interglacial, 123 ka ago? We’velearned a lot about subglacial hydrology andmarine ice sheet dynamics recently, but themagnitude of fluxes, especially sediment fluxto the grounding line, remain conjectural.WISSARD will recover sediments from theGrounding Zone (RAGES) and a subglacial lakebeneath the Whillans ice stream (LISSARD).

These sediments will provide microfossil datato address hypotheses regarding ice sheethistory and subglacial processes, includingconstraining ice stream sediment flux via thesubglacial hydrological system and particle fluxto the subglacial environment from englacialdebris. Microfossils will contribute to theseanalyses, as well as providing a qualitativeassessment of the intensity of subglacialsediment shearing, based on textural data andmorphologic features of the sediment and itsfossils (Geology, 32, 557-511, 2004; J.Nanotech. Nanosci., 5, 96-99, 2005; J. Sed.Geol., 68, 487-469, 1998). Over the nextseveral years, new data from WISSARD, PIG,WAIS divide, and other projects may answernot only Mercer’s first question, but improvethe assessment of the potential for the futuredisaster that he outlined.

Comparative Subglacial Hydrology ofThwaites Glacier, West Antarctica, UsingBasal Specularity

Schroeder, Dustin Schroeder Dustin M;Blankenship Donald D; Young Duncan A D.M.Schroeder, D.D. Blankenship, D.A. Young, ,The University of Texas Institute forGeophysics, Austin, TX

A key control on ice sheet response to climateforcing is the subglacial hydrologic boundarycondition. Airborne ice penetrating radarsounding has been used with variable successto identify and characterize subglacialhydrological systems by the strength of thereturn from the basal interface. We present ameans for improved characterization ofsubglacial hydrology using multiple focusingwindows to separate the diffuse and specularcomponents of the interface return. Thespecularity content of the basal return canindicate the presence and extent of subglacialwater independent of temperature profile andimpurity concentration of the ice column. Weapply this technique to a griddedaerogeophysical survey over the confluence oftributaries to Thwaites Glacier, WestAntarctica, a region of particular interest for itssubglacial hydrology. In the context ofsubglacial hydraulic gradients, we compare thespecularity at the confluence to that for each ofthe tributaries as well as for the trunk andgrounding line. We also compare basal watersystem interpretations from specularity contentto those from more traditional echo strengthanalysis. This survey was collected using a 60MHz coherent ice penetrating radar with alinear frequency modulated waveform with a15 MHz bandwidth. We discuss the potentialvalue of this approach for the generalized


characterization of basal water systems usingradar sounding data.

Subglacial Lake Vostok: a Review ofGeophysical Data Regarding ItsPhysiographical Setting

Siegert, Martin Siegert Martin John; PopovSergey; Studinger Michael M.J. Siegert,School of GeoSciences, University ofEdinburgh, Edinburgh, UNITED KINGDOM; S.Popov, PMGE, 24, Pobeda str., St. Petersburg,RUSSIAN FEDERATION; M. Studinger, Lamont-Doherty Earth Observatory , ColumbiaUniversity, Palisides, NY

Subglacial Lake Vostok is the largest and bestknown sub-ice lake in Antarctica. Theestablishment in the 1990s of its water depth,at over 500 m, led to an appreciation that suchenvironments may be habitats for life and maycontain ancient records of ice sheet change. Asa consequence, Lake Vostok catalyzedsubglacial aquatic environment exploration andresearch. Here we discuss the discovery of thelake, and the various geophysical datasetsthat, in combination, reveal the physiographyof the lake. We also know discuss how thesedata have led to an appreciation of the physicalchemical and biological processes in the lake.The outline of the lake is known with arelatively high degree of accuracy, such that itscoastline and ‘islands’ within the lake are welldefined. The lake is over 250 km long andaround 80 km wide in one place. It liesbeneath 4.2-3.7 km of ice, and exists becausebackground levels of geothermal heating aresufficient to warm the base of the ice sheet tothe pressure melting value. Seismic data, andanalysis of gravity measurements, show thelake to have a bathymetry involving twodistinct basins. One is small (~2000 km3) anddeep (~800 M) in the southern part of thelake, where the ice core is positioned, theother larger region to the north (~10,000km3) is also relatively shallow (~300 m).Analysis of the Vostok ice core has revealedover 200 m of ice that has been accreted tothe underside of the ice sheet. This ice hasprovided a valuable insight into the potentialbiological and chemical setting of the lake. Thesteady inclinations of the ice-water interface(due to the lake being in hydrostaticequilibrium with the ice above), leads todifferential ice-base melting (in the north)versus freezing in the south, which excitescirculation within the lake and potential mixingof the water column. The nature of suchcirculation depends heavily on the chemicalproperties of the water itself, which is notknown at this stage. The age of the lake is

likely to be as old as the ice sheet itself. Thetopographic setting in which the lake sits is farolder than the ice sheet and so we can expectthe lake to have developed at this site for aslong as the ice sheet has been at a continentalsize. This means the lake is possibly as old as14 Ma. The age of the water within the lakewill be related to the age of the ice which meltsinto it, and the level of mixing that takes place.Estimates put that combined age at around 1Ma.

The Identification And PhysiographicalSetting Of Antarctic Subglacial Lakes: AnUpdate Based On Recent Discoveries

Siegert, Martin Wright Andrew; Siegert MartinJohn A. Wright, M.J. Siegert, School ofGeoSciences, University of Edinburgh,Edinburgh, UNITED KINGDOM

We investigate the glaciological andtopographic setting of known Antarcticsubglacial lakes (following a previousassessment by Dowdeswell and Siegert, 2002,based on the first inventory of 77 lakes).Procedures used to detect subglacial lakes arediscussed, including radio-echo sounding (RES,which was first used to demonstrate thepresence of subglacial lakes), surfacetopography, topographical changes, gravitymeasurements and seismic investigations.Recent discoveries of subglacial lakes usingthese techniques are detailed, from which arevised new inventory of subglacial lakes isestablished, bringing the total number ofknown subglacial lakes to 386. Using this newinventory, we examine various controls onsubglacial lakes, such as overriding icethickness and position within the ice sheet, andformulate frequency distributions for the entiresubglacial lake population based on these(variable) controls. We show how the utility ofRES in identifying subglacial lakes is spatiallyaffected; lakes away from the ice divide arenot easily detected by this technique, probablydue to scattering at the ice sheet base. Weshow that subglacial lakes are widespread inAntarctica, and it is likely that many areconnected within well-defined subglacialhydrological systems.

Endurance: Two Missions to Antarcticaand Paths to Advanced Sub-GlacialScience Autonomy

Siegert, Martin Stone William C.; RichmondKristof; Gulati Shilpa; Flesher Chris; HoganBart; Murarka Aniket; Khulman Greg; SiegelVictoria; Doran Peter T; Johnson Andrew E;Obryck Maciej; Priscu John C; McKay


Christopher P W.C. Stone, K. Richmond, S.Gulati, C. Flesher, B. Hogan, A. Murarka, G.Khulman, V. Siegel, , Stone Aerospace / PSC,Inc., Del Valle, TX; P.T. Doran, A.E. Johnson,M. Obryck, Earth and Environmental Sciences,University of Illinois at Chicago, Chicago, IL;J.C. Priscu, Department of LRES, MontanaState University, Boseman, MT; C.P. McKay, ,NASA Ames, Mountain View, CA

Permanently ice-covered liquid waterenvironments are among the leading candidatesites for finding evidence of extant lifeelsewhere in our solar system. In order to havethe proper tools and strategies for exploringthe extant ice-covered planetaryenvironments, we have developed anautonomous underwater vehicle (AUV) namedENDURANCE (Environmentally Non-DisturbingUnder-ice Robotic ANtarctic Explorer).ENDURANCE has just completed the second oftwo Antarctic field seasons with great success.Our new dataset for West Lake Bonney (WLB)includes hi-resolution sonar maps of the lakeincluding through the connecting channel andinto East Lake Bonney, 3D temperature,conductivity, pH, REDOX, photosyntheticallyactive radiation, chl-a fluorometry anddissolved organic matter. The drop sondescience package also included a bottom imagerwhich collected 100’s of images of the benthicmicrobial community and an upward lookingcamera captured information on sedimentdistribution in the ice cover. ENDURANCE is ahighly maneuverable, hovering autonomousunderwater science platform descended fromthe DEPTHX vehicle, both of which weredeveloped under NASA ASTEP funding.ENDURANCE had the specific mission ofdescending through a 5 meter deep melt holein the ice cap of West Lake Bonney, TaylorValley, Antarctica and conducting threeautonomous science tasks: 1) measuring the3D water chemistry of the lake; 2) mappingthe underwater face of Taylor glacier where itenters the lake; and 3) charting thebathymetry of the lake bottom; and then 4)returning safely on its own to the melt hole –barely 0.25 m larger in diameter than thevehicle – from more than 2 kilometers radialrange and rising up the hole to be retrieved fordata download and servicing for the nextmission. Included among these was thedevelopment of an automated sub-sea servowinch and sonde payload with its nine waterchemistry probes, high definition imagingsystem, and bottom ranging altimeter. Aspecialized ice-picking behavior was developedto maximize cast initial proximity to theunderside of the ice sheet and to reduce powerconsumption during casts. The navigation

system was comprised of a three layer filterutilizing high grade dead reckoning, ultrashortbaseline localization, and machine vision. Alsonew were web-based glacier imaging systemsand a 120-degree swath high resolution multi-beam mapping sonar system – used for bothlake bottom and glacier face mapping. Newpower systems and a 3D situational awarenesssystem that incorporated all vehicle geometrysensors were added in time for the 2009 WestLake Bonney mission. Many of thecharacteristics and capabilities of ENDURANCE–now successfully demonstrated in complexunder-ice settings beneath West Lake Bonney -are the types of behaviors that will be neededfor sub-ice autonomous probes to Europa,Enceladas, and other outer planet waterymoons.

Microbial Communities in AntarcticSubglacial Aquatic Environments (SAE)

Skidmore, Mark Skidmore Mark L M.L.Skidmore, Earth Sciences, Montana StateUniversity, Bozeman, MT

Rock-water interactions are fundamental to theglobal geochemical cycles of many elements,including C, Fe, S, Si and P. These interactionsare mediated by microbes in all Earth surfaceenvironments, and the SAE of Arctic and Alpineglaciers and ice sheets are no exception.Glaciological processes under ice masses,including ice sheets provide sustainable habitatfor microbes, forming an aquatic environmentthrough basal melting and providing nutrientsand energy from bedrock comminution.Research over the past decade or so, largelythrough remote sensing techniques hasdemonstrated the abundance of water beneathice sheets, including lakes, channelizeddrainage systems and saturated sediments andhas also highlighted the interconnectivity ofthese water bodies. Water is a key requirementfor microbial life, and its abundance beneaththe Antarctic Ice Sheet indicates a significantvolume of potential microbial habitat that islargely unexplored. Sampling of SAE beneaththe Antarctic Ice Sheet especially formicrobiological research has been limited.Examples are accreted ice from subglacial LakeVostok in East Antarctica and saturated tillfrom beneath the ice streams draining theWest Antarctic Ice Sheet. Viable microbes havebeen detected in these samples and theiractivity measured at temperatures close tofreezing in the laboratory, demonstrating thatin situ activity in subglacial environments isplausible. Additional evidence for in situsubglacial microbial activity in saturated tillscomes from a) physical attributes of subglacial


till particles that include etch pits, oftenindicative of microbially-mediated mineralweathering and b) the geochemistry of the tillpore waters is consistent with biologically-driven sulfide oxidation coupled to carbonateand silicate mineral weathering as a significantsolute source. The diversity and activity ofsubglacial microbial communities depends onthe composition of the glacial flour, and thecontent of labile organic matter, sulfides andFe(III) in particular, which effects the Eh andpH of the micro- and macro-environments. Italso depends on the hydrological properties ofsubglacial system components, that controlswater-rock ratios, water-rock interaction timesand flow through rates, which in turn controlthe supply of dissolved gases and movement ofnutrients and waste products generatedthrough microbial activity. Key differencesbetween Antarctic SAE and those beneathArctic and Alpine glaciers that have been moreextensively studied are the scale of thehydrological systems and their components,potential water residence times, which couldbe orders of magnitude greater in Antarcticsystems and the lack of connectivity betweenoxygenated surface waters and the subglacialenvironment thus potentially leading toenhanced anoxic conditions in certainenvironments. These differences and theirpotential impact on microbial populations inAntarctic SAE will also be discussed.

Subglacial Drainage Events Under OutletGlacier End-members: Byrd Glacier andWhillans Ice Stream

Stearns, Leigh Stearns Leigh A; Fricker HelenAmanda L.A. Stearns, , University of Kansas,Lawrence, KS; H.A. Fricker, , ScrippsInstitution of Oceanography, La Jolla, CA;In the past 5 years, surprisingly activenetworks of subglacial lakes have been foundbeneath the Antarctic ice sheet. However, sofar the only link between subglacial outburstactivity and glacier dynamics was observed onByrd Glacier. There, an outburst flood from tworelatively small lakes released ~1.7km3 of water beneath ByrdGlacier, East Antarctica, and caused a ~10

ENDURANCE: Two Missions to Antarcticaand Paths to Advanced Sub-GlacialScience Autonomy

Stone, William Stone William C. W.C. Stone, ,Stone Aerospace, Del Valle, TX;

Permanently ice-covered liquid waterenvironments are among the leading candidatesites for finding evidence of extant life

elsewhere in our solar system (e.g. on Europaand other Galiean satellites). In order to havethe proper tools and strategies for exploringthe extant ice-covered planetaryenvironments, we have developed anautonomous underwater vehicle (AUV) whichhas generated for the first time, 3-Dbiogeochemical datasets in the extremeenvironment of perennially ice-coveredAntarctic dry valley lakes. ENDURANCE(Environmentally Non-Disturbing Under-iceRobotic ANtarctic Explorer) at the time ofwriting this abstract is 3 days away fromcompleting the second of two Antarctic fieldseasons with great success. Our new datasetfor West Lake Bonney (WLB) includesunprecedented hi-resolution sonar maps of theentire lake including through the connectingchannel and into East Lake Bonney, 3D (at 100m xy and subcentimeter z resolution)temperature, conductivity, pH, REDOX,photosynthetically-active radiation, chl-afluorometry and dissolved organic matter. Thedrop sonde science package also included abottom imager which collected 100’s of imagesof the benthic microbial community and anupward looking camera captured informationon sediment distribution in the ice cover.Variation in ice thickness across the lake wasacquired both by sonar and pressuretransducer readings while the vehicle was atrest under the ice. A forward looking camera inconjunction with swath sonar was used toconfirm the location of the ground line ofTaylor Glacier at the west end of the lake. Ourpreliminary assessment of the data suggeststhat the depth of the grounding line coincideswith anomalous water characteristics near theglacier face, suggesting either a subglacialdischarge or some previously undocumentedmixing phenomenon. ENDURANCE is a highlymaneuverable, hovering autonomousunderwater science platform descended fromthe DEPTHX vehicle, both of which weredeveloped under NASA ASTEP funding.ENDURANCE had the specific mission ofdescending through a 5 meter deep melt holein the ice cap of West Lake Bonney, TaylorValley, Antarctica and conducting threeautonomous science tasks: 1) measuring the3D water chemistry of the lake; 2) mappingthe underwater face of Taylor glacier where itenters the lake; and 3) charting thebathymetry of the lake bottom; and then 4)returning safely on its own to the melt hole –barely 0.25 m larger in diameter than thevehicle – from more than 2 kilometers radialrange and rising up the hole to be retrieved fordata download and servicing for the nextmission. Many of the characteristics andcapabilities of ENDURANCE – now successfully

demonstrated in complex under-ice settingsbeneath West Lake Bonney -- are the types ofbehaviors that will be needed for sub-iceautonomous probes to Europa, Enceladas, andother outer planet watery moons. Thepresentation will discuss all of the above alongwith quantitative engineering data on thedesign and field operation of the ENDURANCEautonomous science platform along withadvanced concepts for sub-ice autonomousscience. www.stoneaerospace.com

Glaciological And Geophysical Studies inDome A, East Antarctica

Sun, Bo Sun Bo; Tang Xueyuan; Li Xin; CuiXiangbin; Zhang Dong B. Sun, X. Tang, X. Li,X. Cui, D. Zhang, , Polar Research Institute ofChina, Shanghai, CHINA

Dome A, located in the central East Antarcticice sheet (EAIS), is the summit of the Antarcticice sheet. During the 21st and 24th ChineseNational Antarctic Research Expedition(CHINARE 21, 2004/05; CHINARE 24,2007/08), ground-based ice radar systemswere used to a three-dimensional investigationin the central 30 km×30 km region at Dome A.The obtained high resolution datasets weretransferred and interpolated into the icethickness distribution , subglacial topographyand internal layers digital elevation model(DEM).The results of the investigation indicatethat the average ice thickness in the Dome Acentral 30 km×30 km region is 2233 m, with aminimal ice thickness of 1618 m and amaximum of 3139 m at Kunlun Station. Thesubglacial topography is relatively sharp, withan elevation range of 949-2445 m. The typicalmountain glaciation morphology is likely toreflect the early evolution of the Antarctic icesheet.The datasets also show some arches andtroughs in isochronous ice layers. There existsome typical synclines and anticlines in icerevealed by ice-penetrating radar in some localregions. To characterize the roughness frombedrock and morphology of internal layersbeneath ice sheets ,a two-parameterroughness index is outlined, the twoparameters are from not only FT of elevations,but also FT of surface slopes. Geometric andglacier dynamical meanings of the roughnessindex are analyzed and discussed. It is shownthat the method can be used to convenientlydemonstrates the spatial distribution ofroughness, without absence of statisticallygeometric information, and could be used toestimate the boundary condition such as basalsliding in glacier dynamics, or differentiate thefactors such as erosion/deposition orcontinental/marine settings in geomorphology.

A 1-D model is used to calculate the past ratesof ice accumulation by internal layering. Anapproximate mean accumulation from 0.018 to0.027m/yr over the past 34.6k years, alongthe RES profiles, was estimated. Also, we havetaken the accumulation was 0.02-0.045m/yr inthe past 34.6-44.6kyr,and 0.01-0.023m/yr inthe past 44.6-84.6kyr along the profile. Thevariability of accumulation in time -spacearound the ice divide also was given.

Enantiomer-specific Isotope Analysis forChiral Amino Acids in Antarctic Sub-glacialEnvironment: Proposal

Takano, Yoshinori Takano Yoshinori Y. Takano,Biogeoscience, JAMSTEC, Yokosuka, JAPAN

The one-handedness of terrestrial L-aminoacids in the proteins and D-sugars of DNA andRNA are essential to the formation, structure,and function of biopolymers for life on Earth.D-amino acids such as D-alanine and D-glutamic acid are significant enantiomers thatis physiologically essential for microbial growthand metabolic maintenance. The nitrogenisotopic difference Δ15ND-L (defined asδ15ND-Ala − δ15NL -Ala) in peptidoglycanamino acids in bacteria such as Firmicutes andActinobacteria (Enterococcus faecalis,Staphylococcus aureus, Staphylococcusstaphylolyticus, Lactobacillus acidophilus,Bacillus subtilis, Micrococcus luteusandStreptomyces) tended to be N-depleted in D-alanine (Δ15ND- −2.0‰). These resultssuggest that the composition of isotopicallyheterogeneous components in these bacteria isprimarily controlled by enzymatic pathwaysprior to formation of the bacterial cell wall. Incontrast, the Δ15ND-L of racemic alanine,simplest chiral amino acid (C3), in the pristinechemical pathway during the nucleophilicsubstitution reaction (SN1 type, produce 50:50racemic mixture) identified fully homogeneouscomponents for each enantiomer. Theenantiomer-specific isotopic analysis (ESIA)method is useful in determining the origins ofchirality in biogenic and abiogenic processes.Consequently, if there is an abiotic synthesis ofamino acids by hydrothermal reactionprocesses in sub-glacial environment,theoretically the Δ15ND-L will be homogeneouscomponents. References [1] Chikaraishi et al.,Determination of aquatic food-web structurebased on compound-specific nitrogen isotopiccomposition of amino acids: Limnology andOceanography: Methods, 7, 740-750 (2009).[2] Takano et al., Compound-specific nitrogenisotope analysis of D-, L-alanine and valine:application of diastereomer separation todelta15N and microbial peptidoglycan studies:


Analytical Chemistry, 81, 394-399 (2009).

Crustal Uplifting Rate Associated WithLate-Holocene Glacial-isostatic Reboundat Skallen and Skarvsnes, Lützow-HolmBay, East Antarctica: Evidence of aSynchrony in Sedimentary and BiologicalFacies on Geological Setting

Takano, Yoshinori Takano Yoshinori Y. Takano,Biogeosciences, JAMSTEC, Yokosuka, JAPAN

We determined the mean crustal uplifting rateduring the late Holocene along the Soya Coast,Lützow-Holm Bay, East Antarctica, by dating amarine–lacustrine transition recorded in lakesediments. We focused on temporal variationsin the chemical composition of sedimentsrecovered from Lake Skallen Oike at Skallenand Lake Oyako at Skarvsnes. Both sets oflake sediments record environmental changesassociated with a transition from marine tolacustrine (fresh water) settings, as indicatedby analyses of sedimentary facies for carbonand nitrogen contents, nitrogen isotopiccompositions (15N/14N), and major elementconcentrations. Changes in the dominantprimary producers during the marine–lacustrine transition were also clearly revealedby biogenic Opal-A, diatom assemblages, andgradient gel electrophoresis (DGGE) with 16SrRNA gene analysis. Geochronology based onradiocarbon dating of acid-insoluble organiccarbon suggested that the environmentaltransition from saline to fresh water occurredat 2940 ± 100 cal yr BP at L. Skallen and 1060± 90 cal yr BP at L. Oyako. Based on thesedata and a linear approximation model, weestimated a mean crustal uplifting rate of 3.6mm yr–1 for the period since the marine–lacustrine transition via brackish condition; thisuplift is attributed to glacial-isostatic reboundalong the Soya Coast. Based on ages obtainedfor the lowermost sediments (crustalbasement), initial sedimentation processstarted by at least 5293–5559 cal yr BP (2σ) atL. Skallen and by 1383–1610 cal yr BP (2σ) atL. Oyako. The geological setting was theprimary factor in controlling the emergenceevent and the occurrence of simultaneouschanges in sedimentary and biological faciesalong the zone of crustal uplift. This study isuseful to understand past sub-glacialenvironments during glacial-erosion processes.

Chemistry Of Vostok Accretion Ice AndPore Waters Beneath The Kamb AndBindschadler Is Consistent With MicrobialLife Beneath The Antarctic Ice Sheet

Tranter, Martyn Tranter Martyn M. Tranter,Bristol Glaciology Centre, University of Bristol,Bristol, 0, UNITED KINGDOM

Interpretation of chemical variations in theaccretion ice at the base of the Vostok Ice Coreis controversial, since saline waters andthermotectonic processes are required toaccount for the variations observed. Here, wepresent a much more simple explanation of thevariations based on known geophysicalcharacteristics of the lake and simple waterand solute mass balance requirements. Weshow that concentrated accretion ice shouldform over the embayment, since theembayment is recharged only with relativelyconcentrated lake water, and that diluteaccretion ice is formed over the open lake,since the lake is recharged with relativelydilute meteoric ice. Our estimated lake andembayment water chemistries are consistentwith the presence of microbially-mediatedgeochemical weathering within the lake. Thecorrespondence of higher microbial counts inthe more concentrated accretion ice isconsistent with the presence of microbes in thesurface waters of the Subglacial Lake Vostok.We compare and contrast the chemicalcompositions of the Vostok waters with thosefrom tills beneath the Bindshadler and KambIce Streams. Again, the chemistry of the sub-ice stream waters is consistent with thepresence of microbially-mediated geochemicalweathering reactions, particularly whenmorphological and mineralogical evidence istaken into account. Together, this worksuggests that microbial life is present in thespectrum waters that make up the sub-icesheet hydrological drainage system, whichincludes subglacial lakes and their inter-connections.

Formation and Preservation of Long-TermPaleoclimatic and PaleoenvironmentalRecords in Subglacial Lakes

Tulaczyk, Slawek Tulaczyk Slawek S.Tulaczyk, Earth Sciences, University ofCalifornia, Santa Cruz, Santa Cruz, CA;

Lacustrine records provide the fundamentalbasis for building understanding ofpaleoenvironmental and paleoclimatic evolutionof non-glaciated continents over timescalesranging from sub-annual to millions of years.Such records represent an important spatial


supplement to deep-sea and continental-shelfmarine sedimentary archives. In Antarctica,ice cores and ice-marginal geologic recordsyielded a wealth of constraints on climatic andenvironmental changes that took place on thiscontinent, and globally, in the last few millionyears. Additional data sets are needed toextend the temporal and spatial footprints ofrelevant observational evidence. Sedimentarysequences in Antarctic subglacial lakes willprovide a new archive of paleoenvironmentaland paleoclimatic records that may greatlyimprove the existing understanding of Antarcticand global climate dynamics. Admittedly,Antarctic subglacial lakes are isolated by thickice from direct atmospheric forcings and inputs(e.g. dust, pollen, etc.), which are often usedin reconstructing past climate andenvironmental changes. However, subglaciallacustrine sedimentation should still besensitive to long-term climate changes (overtimescales >10kyrs) because subglacialhydrology is fundamentally tied to thegeometry, flow rates, and the thermal state ofthe ice sheet. These, in turn, are determinedby climatic factors, such as mean annualtemperatures and accumulation rates. Forinstance, cold and dry climatic periods shouldresult in low basal melting rates and relativelysluggish inputs of basal meltwater intosubglacial lake basins. In lacustrine records,these conditions may be then reflected inlowered sedimentation rates and reducedmaximum sediment grain size because reducedsubglacial water fluxes will have loweredsedimentary capacity and competence. Duringwarmer climatic periods, increased basalmelting rates should lead to highersedimentation rates and larger maximum grainsizes. Even though the ice sheet acts as a low-pass filter for climatic changes, Milankovitch-scale climate variability has sufficiently longperiodicity (>20kyr) to turn out to be arecognizable driver of sedimentary variabilityin subglacial lacustrine sequencesaccumulating over time periods coveringhundreds of thousands to millions of years.This would enable application of well-established orbital tuning techniques todevelop detailed timescales for subglaciallacustrine sequences. As in non-glaciated lakebasins, cyclic climate forcings are likely to beconvolved in subglacial lake settings with localand regional factors that have to do withchanges in interconnectivity of subglacialconduits, internal ice sheet dynamics,volcanic/geothermal events, or subglacialerosion and sedimentation. The value ofAntarctic subglacial lacustrine records will begreatly enhanced if such records containtransition/s from/to pre-glacial to/from

subglacial conditions. There are knownexamples of Northern Hemisphere lake basins,in which overriding ice sheet did not obliteratepre-glacial sedimentary sequences.

Microbial Responses During TheTransition To Polar Night in PermanentlyIce-covered Antarctic Lakes Trista J. Vickand John C. Priscu Montana StateUniversity, Department of Land Resourcesand Environmental Science, 334 LeonJohnson Hall, Bozeman, Monta

Vick, Trista Vick Trista J; Priscu John C T.J.Vick, J.C. Priscu, Land Resources andEnvironmental Sciences, Montana StateUniversity, Bozeman, MT

A majority of the research on the Antarcticcontinent occurs during the austral spring andsummer (October-January), a period ofcontinuous sunlight, when field support isreadily available. Through additional logisticalefforts, we were able to collect the first data onthe MCM lakes during the transition fromsummer to winter (October-April). Acombination of bacterial productivity data and16S ribosomal RNA gene tag sequence librariesallowed us to examine ecosystem responses asphotosynthetic input of new carbon stopped.Microbial protein biosynthesis increased in theeast lobe of Lake Bonney and in Lake Hoareduring March and April (p<0.05); there was nochange in protein biosynthesis in the west lobeof Lake Bonney or in Lake Fryxell. DNAreplication was not affected (p<0.05) by theonset of complete darkness, inferring that thebacteria do not rely directly on phytoplanktonprimary production as their source of organiccarbon during this period. A high rate of dark14 C-labeled bicarbonateincorporation (0.01 to 0.09 µgC l-1 d-1) in one of ourstudy lakes (Lake Fryxell) implies thatchemoautotrophic primary production isimportant in sustaining the ecosystem of thislake during the winter. An overall decouplingof bacterial protein biosynthesis and DNAreplication also occurred during the transitionto winter. Protein biosynthesis increasedrelative to DNA replication as darkness set in,which may signify decreasing rates of celldivision. Such a shift in cellular function, incombination with continued bacterialproduction, indicates that bacterioplankton inthe MCM lakes remain active during the polarnight, but may direct more energy towardssurvival than reproduction. Our results indicatethat concurrent measurement of proteinsynthesis and DNA synthesis in dark, sub-iceaquatic systems can provide important

information on the physiological state of themicroorganisms present.

On the Role of SubglacialBio/Geochemical Processes in GlobalBiogeochemical Cycles - Results fromKamb Ice Stream and ANDRILL

Vogel, Stefan Vogel Stefan Willi S.W. Vogel, ,Northern Illinois University, De Kalb, IL

Subglacial environments play an important rolefor the dynamic of ice sheets and global sealevel change. While subglacial environmentsbeneath alpine glaciers consist of relativelysmall drainage systems, subglacialenvironments in Antarctica and Greenland arecomplex continental scale systems, whichdirectly connect to the ocean. Through intricatefeedback mechanism subglacial processes,including processes in the sub-ice-shelf cavity,influence global ocean circulation andcontribute to the fertility of the ocean. Here wepresent the first geochemical measurements ofbasal water, porewater and sedimentrecovered from the base of Kamb Ice Stream,West Antarctica and reviews them in thecontext of global geochemical cycles andpotential contribution of subglacialenvironments to the fertility of the oceans. Theresults point to an oxygen depleted, sulfaterich, acidic aquatic environment favorable tothe removal of sedimentary carbonate. Theremoval of carbon and other nutrients from thesediment and subsequent transport with theflow of basal water may constitute a significantflux. Chemical processes across the ice sheetgrounding zone, a zone of high saline gradients(low solute freshwater to high saline oceanwater) may trigger either deposition of solutesas observed in the ANDRILL-MIS core, orfurther mobilization of nutrients from sedimentas hypothesized for Fe with subsequentdistribution in the polar ocean. Overallsubglacial environments are far from beingunderstood and it is exciting that upcomingprojects will be able to answer some of thesequestions in the near future. It is howeverimportant to properly understand the effect ofsampling on sample chemistry wheninterpreting the results of these projects.Results from the ANDRILL porewater workindicate a post recovery shift of up to 1 pH.Not considering the pressure and temperatureinduced changes during recovery from a depthof 1000 m or more the results indicate theimportance to combine insitu measurementswith subsequent laboratory work.

Examining The Potential ForMethanogensis in Antarctic SubglacialAquatic Environments

Wadham, Jemma Wadham Jemma L; StibalMarek; Lis Grezegorz; Samyn Denis; TisonJean-Louis; Telling Jon; Anesio Alexandre;Dubnick Ashley; Sharp Martin J; TranterMartyn; Lawson Emily J.L. Wadham, M.Stibal, G. Lis, J. Telling, A. Anesio, M. Tranter,E. Lawson, School of Geographical Sciences,University of Bristol, Bristol, UNITEDKINGDOM; D. Samyn, Glaciology ResearchGroup, University of Uppsala, Uppsala,Uppsala, SWEDEN; J. Tison, Faculte desSciences, Universite Libre de Bruxelles,Brussels, BELGIUM; A. Dubnick, M.J. Sharp,Department of Earth and AtmosphericSciences, University of Alberta, Edmonton,Edmonton, Alberta, CANADA

Antarctic subglacial aquatic environments,including subglacial lakes, are a previouslyneglected component of the Earth’s carboncycle; a reflection of the view held untilrecently that the basal regions of ice sheetsare dominated by abiotic and oxic conditions.Here we consider the potential of theseenvironments as favourable habitats formethanogenic Archaea, and hence sites ofmethanogensis. We employ concentrations ofmethane, carbon dioxide and oxygen in basalice from three glacier/ice sheet systems withcontrasting organic carbon substrates (LowerWright Glacier, Antarctica; Russell Glacier,Greenland Ice Sheet and Finsterwalderbreen,Svalbard) in order to assess the methanogenicpotential in Antarctic subglacial environments.Concentrations of methane in debris rich basalice exceed atmospheric concentrations by upto three orders of magnitude, carbon dioxideconcentrations are also elevated with respectto atmospheric values and oxygen is depleted.These observations are consistent with adiverse and active subglacial microbialcommunity, including heterotrophs andmethanogens. We go on to provide firstevidence of the presence, diversity andabundance of methanogenic Archaea beneaththe Antarctic and Greenland ice sheets,determined using a combination of microscopicand molecular techniques. The abundance ofArchaea in the subglacial sediment samplesfrom Antarctica and Greenland was between103 – 105 cellsper gram of sediment, and most Archaeaspecific 16S rDNA clones were found to beclose to uncultured clones from other types ofcold environments, such as ice-covered lakesand permafrost peat. Between 40 and 60

How Well Do Subglacial Lakes Act asHydraulic Jacks?

Walter, Jacob Walter Jacob I; TulaczykSlawek M; Brodsky Emily E; Schwartz SusanY J.I. Walter, S.M. Tulaczyk, E.E. Brodsky,S.Y. Schwartz, , University of California, SantaCruz, Santa Cruz, CA

Recent evidence suggests that subglacial lakedrainage promotes ice speed-ups (e.g. Stearnset al., 2008). While the drainage of largesubglacial lakes may cause fast ice-flowdownstream, filled or filling subglacial lakesmay promote faster flow over them bydecreasing basal resistance to flow (Sergienkoet al., 2008). Since December of 2007, wehave operated a network of continuouslyoperating GPS receivers on Whillans IceStream (WIS), West Antarctica. The stationsare located on, or near, active subglacial lakes,identified using IceSAT data (Fricker et al.,2007; Smith et al., 2009). We augmented theGPS network with passive broadbandseismometers during the austral summers of2007 and 2008, in order to more closely studythe bi-daily stick-slip events occurring on thelower part of WIS (Bindschadler et al., 2002).Our results indicate that the rupture speed ofthe stick-slip events is dependent upon thefrictional coupling of the basal layer. Yet, thesubglacial layer is not homogenous across allof WIS, as the subglacial lakes provide animportant outlier. Preliminary results from twostations, one on Subglacial Lake Whillans(SLW) and another station ~15 km from theSLW station, indicate that ice immediately overSLW slips less during slip events, as comparedto the adjacent off-lake station. However, theSLW ice flows faster in between slip eventsthan the adjacent station, so that averagedover a few days, the SLW ice flows 8-9 cm/dayfaster than the adjacent station. Ifextrapolated, our results suggest ice directlyoverlying SLW flows ~30 m/yr faster thanadjacent ice. The differences in the nature ofslip events and inter-event creep suggest arapid basal transition over a mere ~15 km.Our observations may yield importantinformation regarding mechanics and dynamicsof ice stream beds at the scale of 10s of km.


Upcoming Chapman Meetings

Chapman Conference on Detachments in Oceanic Lithosphere:Deformation, Magmatism, Fluid Flow, and Ecosystems

Agros, Cyprus8–16 May 2010

Chapman Conference on Giant Earthquakes and Their TsunamisValparaíso, Viña del Mar, and Valdivia, Chile

17–24 May 2010(includes the 50th anniversary of the giant 1960 Chile earthquake and tsunami)

Chapman Conference on Climates, Past Landscapes, and CivilizationsSanta Fe, New Mexico, USA

21–25 March, 2011

Chapman Conference on Source to Sink Around the World and ThroughTime: Recent Advances Understanding Production, Transfer and Burial of

Terrestrial and Marine Materials on the Earth SurfaceSanta Barbara, California, USA

January 2011

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