Lake Vostok

(6) Appendices

Appendix 1 - Presentations on: “Why Lake Vostok?”
3-5 MINUTE PARTICIPANT PRESENTATIONS

Geochemical Overview of the Lake
Berry Lyons
Department of Geology, University of Alabama, Box 870338, Tuscaloosa AL 35487-0338, U.S.A.
p (205) 348-0583, f (205) 348-0818, blyons@wgs.geo.ua.edu

Lyons discussed how the major ion chemistry of the lake might have evolved based on the French research on the chemistry of the Vostok ice core. Because the hydrogen ion is a major caption in the ice during interglacial times, the lake’s water could be acidic.

This might lead to enhanced leaching of particulate matter within or at the sediment-water interface of the lake. In addition, he described the possible N:P ratios of the water (again, based on the ice core results), and suggested that the lake could be very P deficient.

Technologies for Access Holes and Thermal Probes
Stephen R. Platt
Snow & Ice Research Group (SIRG), Polar Ice Coring Office, Snow & Ice Research Group,
University of Nebraska-Lincoln, 2255 W Street, Suite 101, Lincoln, NE 68583-0850, U.S.A.,
p (402) 472-9833, f (402) 472-9832, srp@unl.edu

The Snow & Ice Research Group (SIRG) at the University of Nebraska-Lincoln has conducted a comprehensive analysis of the technological challenges associated with delivering a cryobot-hydrobot transporter vehicle to the surface of Lake Vostok, and has developed a plan that we believe has the highest chance of success and lowest cost consistent with logistical, technical, and time constraints.

The proposed course of action uses a hot water drill to produce a 50 cm diameter access hole approximately 3700 m deep. An instrument carrying thermal probe (the cryobot) will then be deployed from the bottom of this hole to penetrate the final few hundred meters of ice and deliver a hydrobot exploration vehicle to the surface of the Lake.

A division of SIRG, the Polar Ice Coring Office, has a proven capability for drilling 2400 meter deep access holes in ice using a hot water drilling system at the South Pole. The current drill design can be modified to achieve depths of 3500-3700 m. Hot water drilling will not produce a permanent access hole because the hole will begin to refreeze as soon as the water stops circulating.

Once the access hole freezes over, the lake would remain sealed from the outside world, even as the probe entered it. However, because the drilling fluid for this technique is water, the risk of contaminating the Lake is greatly reduced compared to alternative drilling techniques. Furthermore, this is the fastest method for producing large, deep access holes in the ice.

Once the drill equipment is assembled on-site, 3700 m deep holes can be drilled in less than two weeks SIRG has also developed thermal probes for making in-situ measurements of the properties of the Greenland and Antarctic ice sheets. A thermal probe is an instrumented cylindrical vehicle that melts its way vertically down through an ice sheet.

At Lake Vostok, a thermal probe would be lowered to the bottom of the access hole created by the hot water drill, where it would start its descent in to the lake. The probe can be configured to house instruments which measure parameters indirectly through windows in the outer wall of the vehicle, or directly by using melt-water passed through the probe.

This approach is fundamentally different from other means of sampling the physical parameters of ice sheets which usually rely on recovering ice cores. A cable housed within the upper section of the probe unwinds as it moves down through the ice. This cable is used for both data and electrical power transmission between the probe and the support equipment on the surface of the ice sheet.

The probe can only make a one-way trip down through the ice because the melt-water re-freezes behind the probe so it is not recoverable. SIRG is currently doing the preliminary design work for modifying existing probes for use as instrument delivery vehicles, and for integrating in-situ measurement techniques for physical, chemical, and biological phenomena with the cryobot-hydrobot delivery platform.

Helium isotopic measurements of Lake Vostok
Brent D. Turrin
Lamont-Doherty Earth Observatory, Columbia University, Route 9WPalisades New York, 10964, U.S.A.
p (914) 365-8454, f (914) 365-8155, bturrin@ldeo.columbia.edu

Helium isotopic measurements will help provide information on the tectonic environment of Lake Vostok. The input of He into Lake Vostok will come from three discrete sources, atmospheric, crustal, and mantle. These sources of He have distinctly different isotopic signatures. Atmospheric He, accounting for the decay of natural tritium to 3He, will have a R/Ra between 1 to 1.5. Atmospheric He enters the lake via melting ice at the ice-water interface.

If Lake Vostok is located on old stable continental crust, the measured He (helium) will have a R/Ra of 0.01. Because crustal He is dominated by a large input of 4He from radioactive decay of U and Th. On the other hand, if Lake Vostok is located in an active rift environment, the flux of mantle He (R/Ra=6) into the lake would increase the measured He R/Ra to values significantly greater than one.

The He sampling protocol must sample a profile thorough the water column. This is necessary to determine the mixing structures between different He sources.

Molecular Characterization of Microbial Communities
José R. de la Torre & Norman R. Pace
Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA 94720-3102 U.S.A.
p (510) 643-2572, f (510) 642-4995, jtorre@nature.berkeley.edu

It has recently become accepted that microbial organisms thrive in habitats previously deemed too extreme to support life. Lake Vostok represents a new and unexplored habitat, subglacial lakes, which may contain untold biodiversity despite the challenges presented by the physical environment: extreme pressure, darkness, cold and presumably few available nutrients.

The use of molecular techniques in studying microbial populations presents several advantages over traditional survey methods. Most importantly, these methods eliminate the need for laboratory cultivation, since the vast majority (>99%) of microorganisms are refractory to laboratory cultivation using standard techniques. This molecular approach is based on the use of ribosomal RNA (rRNA) sequences to identify population constituents, and to deduce phylogenetic relationships.

This sequence information is obtained by either directly cloning environmental DNA, or by cloning amplified polymerase chain reaction (PCR) products generated using oligonucleotide primers complimentary to either universally conserved or phylogenetic group specific sequences in the rDNA. Comparison of these cloned sequences with those of known rRNA genes reveals quantifiable phylogenetic relationships, independent of morphological and physiological variations, between constituents of the studied community and previously characterized organisms.

These data allow the inference of physiological and metabolic properties based on the properties of known relatives within particular phylogenetic groups. This sequence information can also be used to design fluorescently-labeled oligonucleotide probes to examine the morphology and physical distribution of the novel organisms in the environmental setting.

Contributions of Ice Sheet Models to Understanding Lake Vostok
Christina L Hulbe
Code 971, NASA Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A.,
p (301) 614-5911, f (301) 614-5644, chulbe@ice.gsfc.nasa.gov

Dynamic/thermodynamic numerical models of ice sheet flow should play a role in several aspects in the exploration of Lake Vostok. First, models can be used to characterize the present-day physical environment of the lake. For example, by providing a 3-dimensional view of ice temperature and age, estimating the influx of debris carried by ice flow, and estimating the horizontal flux of ice sheet basal melt-water into the lake.

When coupled with a numerical model of lake water circulation, an ice sheet model can predict the spatial pattern and rate of melting and freezing above the lake. Second, numerical models can investigate the climate-cycle history of the lake. Changes in ice sheet mass balance over the time since the lake was isolated from the atmosphere are likely to have affected Lake Vostok’s area extent, its sediment content, and melt-water flux.

To perform such computations, ice sheet models will need accurate, well-resolved basal topography of the region around the lake and as much information about basal geology and geothermal heat flux as possible. Other input data, such as present-day surface elevation and the local climate record, are available. Indeed, the closeness of the Vostok ice core climate record is ideal.

Numerical-model studies of both present and past lake environments would be useful in both site-selection prior to direct contact with the lake and in interpretation of data retrieved from lake exploration.

Implications of Ice Motion Over Lake Vostok
Ron Kwok
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr.
Pasadena, CA 91109, U.S.A.
p (818) 354-5614, f (818) 393-3077, ron.kwok@jpl.nasa.gov

Ice motion estimates show that the subglacial lake exerts considerable control over the regional ice dynamics. As the ice flows pass the grounding line, there seems to be a pronounced southward component of motion with a profile which increases slowly at the northern tip of the lake and then rather rapidly starting at approximately 100 km along the length of the lake.

Critical to the understanding of past trajectories of the ice recently cored at Vostok Station, and the interpretation of internal layers of the ice sheet from radio echo sounding measurements, the characteristics of the ice motion of the ice sheet as it flows over the lake are important. If flow is normal to the contours over the center of the lake, ice from the lower parts of the Vostok ice core spent on the order of 100,000 yrs traveling down the length of the lake.

In this case, dating core layering should be regular and accurate. If there was a westward component, the age-depth relation in the previously grounded ice core would be less regular than for transport down the lake. The ice motion field also raises numerous interesting questions concerning thermal and mechanical processes in the ice sheet.

It will help in the modeling of bottom melt and accretion; processes which might help localize areas where ecosystems could most likely exist.

The Study & Evolution of an Ancient Ecosystem & Its Evolution
Todd Sowers
Penn State University, Geosciences Dept., 447 Deike Bldg., University Park, PA, 16802 U.S.A.,
p (814) 863-8093, Lab 863-2049 or 863-3819, f (814) 863-7823, sowers@geosc.psu.edu

Why study the Lake?
One fascinating aspect of the lake involves the notion that we may be able to study an ancient ecosystem that has evolved for millions of years. This ecosystem has been effectively isolated from almost every aspect of the biosphere as we know it.

As such, the organisms which inhabit the lake have adapted to a very different environment compared to most of the near-surface ecosystems studied to date. In my mind, the most important reason to study the lake is to document the evolution of the biota within the lake. The results will not only shed light on evolutionary biology here on Earth, but it will also help in the search for life on other (cold) planets.

In terms of my specific contribution to the study of Lake Vostok, I’d be very interested in looking at the isotope systematics of the lake. Specifically, I’d like to look into the stable isotopic composition of O², N², and Ar clathrates which are liable to be floating near the water/ice interface.

There are two interesting aspects of such a study which will need to be considered in parallel; 1) the possibility of dating the lake and 2) providing some constraints on the biogeochemical cycling of O² and N² within the lake.

1) The 18º/16º of O² in the lake may provide some information regarding the age of the lake.
To use the d¹⁸O of clathrate O², we must first assume that the d¹⁸O of paleoatmospheric O² has followed the d¹⁸O of sea water as it apparently has (to a first approximation) over the last 400,000 years (Bender et al., 1994; Jouzel et al., 1996; Sowers et al., 1993).

Then, using the d¹⁸O of benthic forams covering the Tertiary (Miller et al., 1987) as a proxy for the d¹⁸O of sea water (and paleoatmospheric O²), we may be able to ascertain the youngest age of the lake by analyzing the d¹⁸O of clathrate O² from the lake.

If the d¹⁸O of O² is within 1‰ of the present day value, then we can safely say that the lake is probably less than 2.2 myr old. If, on the other hand, the d¹⁸O of O² is between 1 and 3‰ lower than today, then we can say that the clathrates (and lake) are probably between 2.2 and 50 ma (myr before present). Values which are lower than 3‰ could be interpreted as signaling clathrates which are more than 50 myr old.

2) By studying the stable isotope systematics of O², N², and Ar, we may be able to learn something about the biogeochemical cycling of these bioactive elements within the lake. Assuming organisms can be cultured and incubated under conditions approaching Lake Vostok, (and the organisms use/produce O² and N² as part of their metabolic activity), we can determine the community isotope effect for these gases using laboratory incubations. Having this data in hand, along with the isotope measurements on the air clathrates from the lake, we may be able to provide some qualitative estimates of the longevity of the ecosystem via simple isotope mass balance.

Modeling the thermal forcing of the circulation in Lake Vostok
David Michael Holland
Courant Institute of Mathematical Sciences, 251 Mercer Street, Warren Weaver Hall, 907, New York University, MC 0711, New York City, New York, 10012 U.S.A.
p (212) 998-3245, f (212) 995-4121, holland@cims.nyu.edu

Lake Vostok is situated at the base of the huge Antarctic Ice Sheet. The isolation and remoteness of the lake imply that it will have a circulation driven by the heat and freshwater fluxes associated with phase changes at the ice sheet - lake surface boundary.

While geothermal fluxes would also play a role at the lake bed interface, the nature of these important, but poorly known fluxes for Lake Vostok, are not considered in the present discussion. A hierarchy of formulations that could be used to describe the heat and mass transfer processes at the lake surface are presented. The main difference between them is the treatment of turbulent transfer within the lake surface boundary layer.

The computed response to various levels of thermal driving and turbulent agitation in the upper layers of the lake is discussed, as is the effect of various treatments of the conductive heat flux into the overlying ice sheet. The performance of the different formulations has been evaluated for the analogous environment of an oceanic cavity found beneath an ice shelf.

In an effort to understand what the physical circulation is in the lake and subsequently of what relevance it might be to chemical and biological activity in the lake, the following investigation is proposed: An investigation of the details of the thermal interaction between the lake and the overlying ice sheet could be pursued by building on existing theoretical and modeling studies of other cold liminological/oceanographical environments.

The detection of life - Nucleotide fingerprints
David M. Karl
School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, U.S.A.
p (808) 956-8964, f (808) 956-5059, dkarl@soest.hawaii.edu

Perhaps the first question that one should ask about “life” in Lake Vostok is...is there any? If the answer is yes, then one needs to ask how much life is there, how rapidly is the crank turning and what kind of life forms are present. Although there are numerous methods available to address these fundamental ecological questions, only a relatively few have the sensitivity required for the detection of low standing stocks of microorganisms that might occur in the hyperoligotrophic Lake Vostok.

Adenosine 5’-triphosphate (ATP) is present in all living cells where it functions as an essential link between energy generation and biosynthesis and as a precursor for RNA and DNA synthesis. Furthermore, in concert with related cellular nucleotides (e.g., ADP, AMP, GTP, cAMP, ppGpp), ATP also serves to regulate and direct cellular metabolism. In addition, ATP and associated nucleotide biomarkers can be extracted from cells and measured in situ; hence sample return is not mandatory, although it is desirable.

ATP has already proven to be useful in many ecological studies of remote and extreme environments including the deepest portions of the Aleutian Trench (>7500m), hydrothermal vents and ice covered polar habitats.

Alternative Mechanisms for Organic Syntheses and the Origin of Life: Lake Vostok as a Case Study
Luann Becker
University of Hawaii, Manoa, 2525 Correa Rd., Honolulu, HI 96822, U.S.A.
p (808) 956-5010, f (808) 956-3188; lbecker@soest.hawaii.edu

One of the more exciting new fields of research that is emerging within the deep-sea drilling program is the search for a subsurface biosphere. This field has developed as a result of the study of extreme environments and their possible link to the first living organisms that inhabited the early Earth.

Recent experimental data show that amino acids can be activated under plausible ‘Prebiotic’ geologic conditions [nickel, iron (Ni,Fe) sulfide (S) and carbon monoxide (CO) in conjunction with hydrogen sulfide (H²S) as a catalyst and condensation agent at 100^oC, pH 7-10 under anaerobic, aqueous conditions; Huber and Wachtershauser (1998)]. These findings support a thermophilic origin of life and the early appearance of peptides in the evolution of a primordial metabolism.

Other research efforts have focused on identifying alternative energy sources available in hydrothermal regimes as supporting a deep subsurface biosphere. For example, it has been suggested that hydrogen produced from basalt-ground-water interactions may serve as an energy source that supports the existence of microorganisms in the deep subsurface of the Earth (Steven and McKinley, 1995).

However, Anderson et al., (1998) have demonstrated experimentally that hydrogen is not produced from basalt at an environmentally relevant alkaline pH. Furthermore, geochemical considerations suggest that previously reported rates of hydrogen production couldn’t be sustained over geologically significant time frames. Nevertheless, results from the Anderson et al., (1998) study do not rule out the possibility that reduced gases emanating from deeper in the Earth could fuel deep subsurface microbial ecosystems (Gold, 1992).

Finally, the hypothesis that a reducing lithosphere on the early Earth would have resulted in an ammonia-rich atmosphere was tested experimentally by using a mineral catalyst to reduce N², NO²- and NO³- to ammonia (NH³) under typical crustal and oceanic hydrothermal conditions (Brandes et al., 1998). Results of this study showed that oceanic hydrothermally derived ammonia could have provided the reservoir needed to facilitate the synthesis of these compounds on the early Earth.

All of these studies indicate that a direct evaluation of the subsurface biosphere ecosystem is needed to assess the plausibility that organic syntheses capable of supporting life can occur in this environment. A planned program to sample water, porewater and sediment samples for the detection of organic components (i.e. amino acids, peptides etc.) is necessary to ascertain the mechanism of formation (abiotic or biotic) and further determine whether the organic components detected are capable of supporting or synthesizing a subsurface biosphere.

These samples can be collected and examined on board using conventional organic geochemical approaches (i.e. HPLC, PY-GCMS, etc.). In addition, a planned re-entry program will allow us to measure for organics in situ downhole (e.g. state-of–the-art fiber-optic fluorescence or micro-Raman approaches). The use of fluorescence for the detection of organic compounds is an extremely versatile and sensitive technique (detection at the sub-femtomole level).

The development of an ‘Organic Probe’ that we can attach to a re-entry device to detect organic components ‘real-time’ in the Lake Vostok aqueous and sedimentary environment is needed. These measurements are critical to the assessment of contamination that may be introduced during the sampling program.

Thus, the instrument implementation and the results obtained will be important to future investigations of life in extreme environments on Earth and perhaps beyond (e.g. Europa).

Hypotheses about the Lake Vostok Ecosystem
Diane McKnight
INSTAAR, University of Colorado, 1560 30th St., Boulder, CO 80309-0450, U.S.A.,
p (303) 492-7573, f (303) 492-6388, Diane.McKnight@Colorado.edu

Lake Vostok allows us an opportunity to extend our knowledge of ecosystem processes to a new extreme environment; one in which there has been sufficient time for microorganisms to adapt. Our approach should be to develop ecosystem hypotheses based upon current knowledge. Our current knowledge of environments of this type is based on the Dry Valley ecosystem characteristics.

Dry Valley ecosystem characteristics:

1. Autotrophs in lakes and streams are adapted to use low energy, e.g. photosynthesis begins with sunrise.
2. Relict organic carbon sustains ecosystems at a slow rate over long periods, e.g. soil system runs on old algal carbon.
3. All landscape components - lakes, streams, soils - have a food web, e.g. “microbial loop” in lakes.
4. In the lakes, viable organisms persist through winter and mixotrophs become abundant.

Hypotheses about the Lake Vostok ecosystem:

1. Autotrophic microorganisms exist and use chemical energy sources at very low fluxes.
2. The Lake Vostok ecosystem will be primarily heterotrophic, with organic compound deposited with snow on plateau as an organic carbon source.
3. The Lake Vostok ecosystem will have a microbial look, including mixotrophs and grazers.

*Even if DOC of glacier ice is 0.1 mg C/L, this DOC may be a greater energy source than those available to support autotrophic processes. One could hypothesize that humics in Lake Vostok water would have a different signature than humics in overlying glacier ice because of microbial processing.

Plan for discoveries, for unexpected observations
It should be noted that studies in the Dry Valleys began in the 1960s, and were not conducted with a focus on avoiding the introduction of exotic microorganisms. Although there is not evidence of introduced algal species becoming abundant, we have not assessed introductions as an ecological factor.

For isolated inland locations, introductions should be a concern because equipment or food could transport species that do not survive long range aeolian transport.

A Terrestrial Analog
Mark Lupisella
NASA Goddard Space Flight Center, Greenbelt Rd., Mailstop 584.3, Building 23, Rm. W207, Greenbelt, MD 20771, U.S.A.
p (301) 286-2918, f (301) 286-2325, Mark.Lupisella@gsfc.nasa.gov

A key challenge for a human mission to Mars will involve assessing and minimizing adverse impacts to the indigenous environment, where “adverse” means anything that could compromise the integrity of scientific research-especially the search for life. Due to the extreme surface conditions of Mars, signs of Martian life, if they exist at all, are likely to be under the surface where there is thought to be a layer of permafrost.

It is also possible that sub-glacial lakes exist under the polar caps of Mars. Humans on Mars will eventually have to drill for many reasons, including the search for life, so Lake Vostok should be considered as a terrestrial analog for understanding how humans might conduct such drilling activities on Mars-particularly regarding issues of contamination control.

Microbial Sample Characterization and Preservation
David Emerson
American Type Culture Collection, 10801 University Blvd., Manassas, VA 20110-2209, U.S.A.,
p (707) 365-2700, f (707) 365-2730, demerson@gmu.edu

Characterization and preservation of samples of microbes that are returned from Lake Vostok will be a vital aspect of any attempt to study the life that lives in the Lake. The American Type Culture Collection (ATCC) houses the world’s most diverse collection of microorganisms, and includes large collections of prokaryotes, fungi, and free-living protists. Members of all these groups are likely to be found in Lake Vostok waters.

ATCC scientists are well versed in the methods of cryopreservation and lyophilization of microbes, and microbe containing samples, as well as in isolation and characterization of the microbes themselves. Recently, the ATCC has acquired the ability to carry out more extensive genomic analysis of isolates, including sequencing of SSU rRNA genes, DNA fingerprinting, and hybridization technologies.

In addition, the ATCC has a strong bioinformatics group with experience in developing databases concerning specific groups of microorganisms. The ATCC would be a willing participant in efforts to preserve and characterize samples returned from Lake Vostok.

Some of the issues regarding sample handling from the Lake would involve returning unfrozen samples through the ice sheet for culturing. It is known that one freeze/thaw cycle can significantly diminish the number of viable organisms in a sample and can be especially hard on the protists.

An alternative would be to inject cryopreservatives into samples in situ so freezing upon return would be less deleterious, although some protists will not tolerate any freezing at all. Once samples are returned to the surface, it will be important to have the logistical support in place to insure that they remain close to ambient temperature (assuming the ambient temperatures are near 0°C, and not from a ‘hot spot’) during any transport and handling back to the laboratories where they will be processed. In addition, assuming samples are returned unfrozen, it would be wise to preserve a subset of samples with different cryopreservatives for archival maintenance.

In terms of cultivating microbes, and especially novel prokaryotes from Lake Vostok samples, the most interesting habitat from a physiological perspective would be the putative gas clathrates that exist in the Lake. While methane clathrates are known to exist at cold seeps in the Gulf of Mexico, and other deep-sea environments, relatively little microbiological work has been done with these, and environments suitable for life containing other types of gas clathrates are even less known.

These unusual chemical conditions are most likely to lead to unusual metabolic/phylogenetic types of microbes. Understanding and reproducing the conditions whereby it might be possible to culture these organisms will be important, and will require collaboration between chemists and microbiologists to establish the best methods.

It would be best to have the protocols for these methods worked out prior to sample return; for cultivation studies it is best to use ‘fresh’ samples and there may be a relatively narrow window of a few weeks to have the highest rate of success for cultivation. Finally, from a culture collection perspective, it would be ideal to have thorough documentation procedures in place for any biological samples collected from Lake Vostok.

This would include a WWW accessible database that would catalog where samples were taken, how they were preserved, where they were distributed, and a summary of the results obtained for each sample, including the ultimate deposition of any isolated microbes from the samples with a major culture collection.

Ready access to this information would insure the widest participation of the whole scientific community in what is likely to be a highly unique and exciting, though costly, endeavor.

Motivation for Sampling Hydrates and Sediments
Peter T. Doran
University of Illinois at Chicago, Department of Earth and Environmental Sciences, 845 W. Taylor St., Chicago, Illinois, 60607-7059, U.S.A.
p (312) 413-7275 f (312) 413-2279, pdoran@dri.edu, pdoran@uic.edu

The impetus to study a deep subglacial lake such as Lake Vostok will undoubtedly be driven by the investigation of life’s extremes on this planet. Extremes for life in Lake Vostok will include high pressure (for a freshwater environment), low nutrient levels, absence of light, and all gases being in hydrated form.

Lake Vostok is analogous to the bottom 500 m of a 4 km deep freshwater lake with a 3.5 km perennial ice cover. The motivation for studying Lake Vostok is similar to the motivation for studying other unique and extreme habitats such as Antarctic Dry Valley lakes, hydrothermal vents, and the deep Earth.

Defining modern life’s extremes is critical to understanding the origins and evolution of life on this planet and others. Having said this, science at Lake Vostok should not be limited to the search for life. If no life exists in Lake Vostok we will want to know why, which will require a detailed biogeochemical sampling of the lake. Furthermore, the water column and sediments of Lake Vostok should offer new and exciting sources of paleoenvironmental information (e.g. CO² clathrate record, extraterrestrial flux), even in the absence of a viable lake community.

The sediment record could conceivably extend well beyond ice core records. The first stage of any Lake Vostok study should be exploration with in situ instruments, but in situ monitoring will fall short of answering the key science questions (particularly in the sediment record).

Samples will need to be brought to the surface, which appears feasible with some technology development. Access and retrieval technologies should be tested in a smaller, logistically convenient subglacial lake or analogous environment prior to going to Vostok.

Some Factors Influencing Circulation in Lake Vostok
Eddy Carmack
Institute of Ocean Sciences, Institute of Ocean Sciences, 9860 West Saanich Rd.
P.O. Box 6000, Sidney BC V8L4B2, Canada,
p (250) 363-6585, f (250) 363-6746, CarmackE@pac.dfo-mpo.gc.ca

Density-driven flows are likely to dominate water motion within Lake Vostok. Hence, consideration must be given to

(1) the equation of state of fresh water

(2) the effect of pressure on freezing point

(3) potential material flux from the overlying ice

(4) geothermal heating from below

In turn, these factors may be modified by sloping boundaries, e.g. along the ice-water interface (ceiling) and water-sediment (floor) of the lake. Some simple constraints follow from basic thermodynamic considerations.

The depression of the temperature of maximum density (TMD) with pressure is given by TMD(S, p) = TMD(0, p) - 0.021p, where p is pressure in bars or 105 Pa (Chen and Millero, 1986). The depression of the freezing temperature (TFP) with pressure is given by TFP(S, p) = TFP(S, 0) ñ 0.00759p (Fujino et al., 1975).

Taking TMD(0, 0) ~ 4^oC and TFP(0, 0) ~ 0^oC we see that the two lines cross at a critical pressure (pcrit) of about 305 bars, which corresponds to an overlying ice thickness of about 3350 m. Above this critical pressure TMD > TFP and the system is stable when (T/(Z > 0); that is, it behaves as a lake.

Below this pressure TMD < TFP and the system is stable when (T/(Z < 0); that is, it behaves as an ocean. It appears that pressures with Lake Vostok place it in the “ocean” category. Other Antarctic lakes, for example the one at South Pole, may fall into the “lake” category.

An interesting situation would arise if pcrit were to lie internal to the lake, yielding bimodal flow conditions. External sources of buoyancy to the system include geothermal heating (perhaps ~ 50 mWm-2) and particle fluxes (unknown, but, if existent, likely to be highly localized).

Lateral gradients of buoyancy may also arise from boundary conditions at the sloping ceiling (required to be at the local TFP) and bottom (derived from either geothermal effects or solute flux). It is noted that examples are found elsewhere in nature where extreme pressures affect water stratification and motion; for example in the oceans off Antarctic ice shelves (Carmack and Foster, 1975) and in deep lakes such as Baikal (Weiss et al., 1991).

Prior to in situ measurements of circulation in Lake Vostok, possible scales of motion should be explored with simple models. Also, field experiments could be carried out to see if flow can be detected in similar but less extreme high pressure and low temperature situations (e.g. beneath the Ward Hunt Ice shelf off Ellsmere Island (Jefferies, 1992).

Figure Caption
Concerning water column stratification, three types of lakes under ice can be expected in Antarctica, depending on whether the ice thickness is larger or less than the depth, where freezing temperature TF and the temperature of maximum density TMD are identical (3170 m ice). Lake Vostok, where TF (lake temperature = -2.7^oC) is warmer than TMD ( -4^oC), thermal expansivity a is positive and subsequently density sT decreases with depth, as typical under convective instability.

Back to Contents

Appendix 2 - Workshop Program
Lake Vostok Workshop - “A Curiosity or a Focus for Interdisciplinary Study?”
An NSF Sponsored Workshop
Washington D.C.
November 7 & 8, 1998

Conveners

Robin E. Bell, Lamont-Doherty Earth Observatory, Oceanography, Rt. 9W, Palisades, New York
10964, Phone: 914-365-8827, E-mail: robinb@ldeo.columbia.edu
David M. Karl, School of Ocean and Earth Science and Technology, University of Hawaii,
Honolulu, HI 96822, Phone 808-956-8964, E-Mail: dkarl@soest.hawaii.edu

WORKSHOP GOAL
The goal of the Lake Vostok workshop will be to stimulate discussion within the US science community on Lake Vostok specifically addressing the question:

“Is Lake Vostok a natural curiosity or an opportunity for uniquely posed interdisciplinary scientific programs?”

The workshop will attempt to develop an interdisciplinary science plan for studies of the lake.

WORKSHOP STRUCTURE
The workshop will open with a series of short talks setting the background on Lake Vostok. Prior to the meeting a package of information on Lake Vostok will be distributed to ensure that the group has adequate background. Following the background talks, each participant will be provided an opportunity to share their focused thoughts on Lake Vostok, and critical information or research directions they would like to see pursued.

In the following day and a half the group will break into cross disciplinary groups to develop a sequence of key science objectives and a strategy to carry them out. Each group will present its plan to the full workshop group and the results will be discussed.

PROGRAM
Saturday 11/7/98

8AM - 8:45 AM Continental Style Breakfast at AGU facilities
9:00 Welcome and Introduction (Robin Bell & David Karl)
9:15 NSF Charge (Julie Palais)
9:30

Overview talks on Lake Vostok
Review of studies to Date (Robin Bell)
The Overlying Ice (Martin Siegert)
Possible Lake Samples - Basal Ice (Jean Robert Petit)

10:30 Break
10:45

Geologic Framework
Biodiversity Questions
NASA & Lake Vostok
How to Identify Life

(Ian Dalziel)
(Jim Tiedje)
(Frank Carsey)
(David White/Roger Kern)

12:30 lunch break (lunch provided for group)
1:30 PM session
1:30 *Why Lake Vostok? 3-5 minute - 1 overhead presentations from participants (see section labeled “Why Lake Vostok” for more information)
3:30 Break
3:45 Break into Discipline Based Groups to Develop List of Key Questions
4:45 Present Key Questions & Discuss linkages
6:00 Reception at AGU

Sunday 11/8/98

8:00-845 Continental Style Breakfast @ AGU facilities
9:00 Review Linkages Break into Interdisciplinary Groups to

(1) Develop Questions
(2) Research Plan

12:00 lunch break (lunch provided for group)
1:00 Groups Present Summaries Discussion
4:00 Adjourn

Back to Contents

APPENDIX 3 - WORKSHOP PARTICIPANTS

Back to Contents

(7) Acknowledgements

This workshop and report were sponsored and supported by the National Science Foundation under grant number OPP-9820596. We would especially like to thank Julie Palais, Polly Penhale and Dennis Peacock from the Office of Polar Programs for their commitment to this project.

Each of the workshop participants contributed to this report through their involvement in developing a science plan for the study of Lake Vostok, and their written contributions to the individual and group reports. We greatly appreciate the editorial skills of Mahlon Kennicutt II, Cynan Ellis-Evans, Berry Lyons and Frank Carsey in blending the writing styles of the numerous authors, and in calling for clarification of the many scientific terms used by the various disciplines represented in the report.

Margie Turrin provided critical assistance in the workshop organization as well as the editing and production of the final report.

Back to Contents

(8) References

Abyzov, S.S., 1993. Antarctic Microbiology (E.I. Friedmann, ed.). Wiley-Liss, New York, 265295.
*Abyzov, S.S., I. N. Mitskevich, M. N. Poglazova, 1998. Microflora of the deep glacier horizons of Central Antarctica. Microbiology (translated from Russian), 67, 451-458. Anderson, R. T., F. H. Chapelle, D. R. Lovley, 1998. Evidence against hydrogen-based microbial ecosystems in basalt aquifers. Science, 281, 976-977.
Bender, M. L., T. Sowers, L. Labeyrie, 1994. The Dole effect and its variations during the last 130,000 years as measured in the Vostok ice core. Global Biogeochemical Cycles, 8, 363-376. Brandes, J. A., N. Z. Boctor, H. S. Yoder Jr.,. 1998. Abiotic nitrogen reduction on the early Earth.
Nature, 395, 365-367.
Cameron, R. E. and F. A. Morelli, 1974. Viable microorganisms from the ancient Ross Island and Taylor Valley drill core. Antarctic Journal of the United States, 9:113-116. Cameron, R. E., F. A. Morelli and R. M. Johnson, 1972.
Bacterial species in soil and air of the Antarctic continent. Antarctic Journal of the United States, 7:187-189.
Carmack, E. C. and Foster, T. D., 1975. Circulation and distribution of oceanographic properties near the Filchner Ice Shelf. Deep-Sea Research, 22, 77-90.
Chen, C. T. and Millero, F., 1986. Precise thermodynamic properties for natural waters covering only the limnological range. Limnology and Oceanography, 31, 657-662.
Chyba, C., 1996. Life on other moons, Nature, 385, 201.
Dalziel, I.W.D., 1997. Neoproterozoic-Paleozoic geography and tectonics: Review, hypothesis and environmental speculation. Geological Society of America Bulletin, 109, 16-40. De Angelis, M., N. I. Barkov, V. N. Petrov, 1987. Aerosol concentrations over the last climatic cycle (160kyr) from an Antarctic ice core. Nature, 325, 318-321.
Drake, J.W., et al., 1998. Rate of spontaneous mutation. Genetics Society of America, 148, 1667-1686.
Duval, P., V. Lipenkov, N. I. Barkov, S. de La Chapelle, 1998. Recrystallization and fabric development in the Vostok Ice Core. Supplement to EOS Transactions Fall 1998 Meeting, AGU, 79, 45, F152.
Ellis-Evans, J.C. and D. Wynn-Williams, 1996. A Great Lake Under Ice. Nature, 381, 644-646.
Fisk, M. R., S. J. Giovannoni, I. H. Thorseth, 1998. Alteration of oceanic volcanic glass: Textural evidence of microbial activity. Science, 281, 978-980.
Fujino, K., E. L. Lewis, R. G. Perkin, 1974. The freezing point of sea water at pressures up to 100 bars. Journal of Geophysical Research, 79, 12, 1792-1797.
Gilichinsky, D., S. Wagner, T. Vishnevetskaya, 1995. Permafrost microbiology, in Permafrost and Periglacial Processes, 6, 281-291.
Gold, T., 1992. The deep, hot biosphere. Proc. National Academy of Sciences USA, 89: 60456049.
Haberstroh, P. R. and Karl, D. M., 1989. Dissolved free amino acids in hydrothermal vent habitats of the Guaymas basin. Geochimica et Cosmochimica Acta, 53, 2937-2945.
Hoffman, P. F., Kaufman, A.J., Halverson, G.P, D. P. Schrag, 1998ª. A Neoproterzoic Snowball Earth, Science, 281, 1342-1346.
Hoffman, P. F., Kaufman, A.J., Halverson, G.P., 1998b. GSA Today, 8 (5), 1-9.
Hofmann, H.J., G.M. Narbonne, J.D. Aitken, 1990. Geology, 18, 1999.
Huber, C. and Wachtershauser, G. 1998. Peptides by activation of amino acids with CO on (Ni,Fe)S surfaces: Implications for the origin of life. Science, 281, 670-672.
Jefferies, M. O., 1992. Arctic ice shelves and ice islands: Origin, growth and disintegration, physical characteristics, structural-stratigraphic variability, and dynamics. Reviews of Geophysics, 30, 245-267.
Jouzel, J., C. Waelbroeck, T. Sowers, 1996. Climatic interpretation of the recently extended Vostok ice records. Climate Dynamics, 12, 513-521.
*Kapitsa, A.P., J. K. Ridley, G. de Q. Robin, M. J. Siegert, I. A. Zotikov, 1996. A large deep freshwater lake beneath the ice of central East Antarctica. Nature, 381, 684-686.
Karl, D. M., 1995. In the Microbiology of Deep-Sea Hydrothermal Vents, (ed. D.M. Karl) pp. 35124, CRC Press, Boca Raton, Florida.
Kirschvink, J.L., 1992. In The Proterozoic Biosphere, J.W. Schopf and C. Klein, Eds., Cambridge University Press, New York, pp.51-52.
Knoll, A.H., 1992. The Early Evolution of Eukaryotes: A Geological Perspective. Science. 256, 622.
Kwok, R., F. D. Carsey, M. J. Siegert, R. E. Bell, 1998. Ice Motion Over Lake Vostok. Supplement to EOS Transactions Fall 1998 Meeting, AGU, 79, 45, F150. Lacy, G. H., R. E. Cameron, R. B. Hanson and F. A. Morelli, 1970. Microbiological analyses of snow and air from the Antarctic interior. Antarctic Journal of the United States, 5: 88-89. Lawrence J.G. and H. Ochman, 1998. Molecular archaeology of the Escherichia coli genom. Procedures of the National Academy of Science, 95, 9413-9417.
Legrand, M. and Mayewski, P. 1997. Glaciochemistry of polar ice cores: A review. Reviews of Geophysics, 35, 219-243.
Leitchenkov, G.L., S. R. Verkulich, V. N. Masolov, 1998. Tectonic setting of Lake Vostok and possible information contained in its bottom sediments. Lake Vostok Study: Scientific Objectives and Technological Requirements, International Workshop, Arctic and Antarctic Research Institute, St. Petersburg, Russia, 62-65.
Mayer, C., and M. J. Siegert,Numerical modeling of ice-sheet dynamics across the Vostok subglacial lake, central East Antarctica. Journal of Glaciology (submitted).
Miller, K. G., R. Fairbanks, G. Mountain, 1987. Tertiary oxygen isotope synthesis, sea level history, and continental margin erosion. Paleoceanography, 2, 1-19.
Mottl, M. J. 1992. Pore waters from the serpentinite seamounts in the Mariana and Izu-Bonin Forearcs, Leg 125: Evidence for volatiles from the subducting slab. Proc. of the Ocean Drilling Program Scientific Results, 125, 373-385.
Petit, J.R., I. Basile, J. Jouzel, N. I. Barkow, V. Ya. Lipenkov, R. N. Vostretsov, N. I. Vasiliev, C. Rado, 1998. Preliminary investigations and implications from the 3623 m Vostok deep ice core studies. Lake Vostok Study: Scientific Objectives and Technological Requirements, International Workshop, Arctic and Antarctic Research Institute, St. Petersburg, Russia, 43.
Petit, J.R., J. Jouzel, D. Raynaud, N.I. Barkov, J.-M. Barnola, I. Basile, M. Benders, J. Chappellaz, M. Davis, G. Delaygue, M. Delmotte, V.M. Kotlyakov, M. Legrand, V.Y. Lipenkov, C. Lorius, L. Pepin, C. Ritz, E. Saltzman & M. Stievenard. 1999. Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature, 399, 429-436.
Popkov, A.M., G.A. Kudryavtsev, S.R. Verkulich, V.N. Masolov, V.V. Lukin, 1998. Seismic studies in the vicinity of Vostok Station (Antarctica). Lake Vostok Study: Scientific Objectives and Technological Requirements, International Workshop, Arctic and Antarctic Research Institute, St. Petersburg, Russia, 26.
Priscu, J.C., C. H. Fritsen, J. L. Pinckney, 1998. Perennial Antarctic Lake Ice: An Oasis for Life in a Polar Desert. Science. 280, 5372, 2095.
Robin, G. de Q., 1998. Discovery and ice dynamics of the Lake Vostok region. Lake Vostok Study: Scientific Objectives and Technological Requirements, International Workshop, Arctic and Antarctic Research Institute, St. Petersburg, Russia, 19-20.
Salamatin, A.N., 1998. Modeling Ice Sheet Dynamics and heat transfer in central Antarctica at Vostok Station. Conditions of the subglacial lake existence. Lake Vostok Study: Scientific Objectives and Technological Requirements, International Workshop, Arctic and Antarctic Research Institute, St. Petersburg, Russia, 36-37.
Sharp, M., J. Parks, B. Cragg, I. Fairchild, H. Lamb, M. Tranter, 1999. Widespread bacterialpopulation at glacier beds and their relationship to rock weathering and carbon cycling, Geology, 27, 107-110.
*Siegert, M J., J. A. Dowdeswell, M. R. Gorman, N. F. McIntyre, 1996. An inventory of Antarctic subglacial lakes. Antarctic Science, 8, 281-286.
Siegert, M.J., and Ridley, J.K., 1998. An analysis of the ice-sheet surface and subsurface topography above the Vostok Station subglacial lake, central East Antarctica. Journal of Geophysical Research, 103, B5, 10,195-10,208.
Siegert, M.J., R. Hodgkins, J. A. Dowdeswell, 1998. A chronology for the Dome C deep ice-core site through radio-echo layer correlation with the Vostok ice core, Antarctica. Geophysical Research Letters, 25, 1019-1022.
Sowers, T., M. Bender, L. Laurent, 1993. 135,000 Year Vostok-SPECMAP common temporal framework. Paleoceanography, 8, 737-766.
Steven, T. O. and McKinley, J. P., 1995. Lithoautotrophic microbialecosystems in deep basalt aquifers. Science, 270, 327-330.
Veevers, J.J., 1994. Case for the Gamburtsev Subglacial Mountains of East Antarctica originating by mid-Carboniferous shortening of an intracratonic basin. Geology, 22, 593-596.
Veevers, J.J., C. McA. Powell, O. R. Lopez-Gamumdi, 1994. Synthesis. In Permian-Triassic Pangean basins and fold belts along the Panthalassan Margin of Gondwanaland. Boulder, Geological Society of America Memoir, 184, 331-353.
Wedepohl, K.H., 1995. The composition of the continental crust. Geochimica et Cosmochimica Acta, 59, 1217-1232.
Weiss, R. F., E. C. Carmack, V. M. Koropalov, 1991. Deep water renewal and biological production in Lake Baikal. Nature, 349, 665-669.
Williams, D. M., J.F. Kastings, R.A. Wade, 1997. Habitable moons around extrasolar giant planets, Nature, 385, 234-235.
Zotikov, I.A., 1998. Subglacial melting in central Antarctica and development of knowledge about subglacial Lake Vostok. Lake Vostok Study: Scientific Objectives and Technological Requirements, International Workshop, Arctic and Antarctic Research Institute, St. Petersburg, Russia, 14.

*Article included in background reading section (9)

Back to Contents