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SCAR Bulletin 146, July 2002

SCAR Group of Specialists on Subglacial Antarctic Lake Exploration

Brief Report of a Meeting

A meeting of the SCAR Group of Specialists on Subglacial Antarctic Lake Exploration was held in Bologna, Italy, 29 - 30 November 2001. The following members of the Group were present: J C Priscu (Convener), M C Kennicutt II (Secretary), R E Bell, S Bulat, J C Ellis-Evans, V Lukin, R D Powell, and I Tabacco. Members J-R Petit and H Miller were unable to attend. Invited guests and observers included E Blake, F D Carsey, P Egerton, K A Erb, H Gavaghan, P Mulgarin, J R Shears, and M Zucchelli.

Evolution of Subglacial Antarctic Lake Exploration

J. Priscu, Convener, provided a brief reprise of the history of interest in subglacial lakes that set the stage for the formation of the Group of Specialists. The history of subglacial lake exploration can be considered to have occurred in three stages: discovery and serendipity (1955 - 75), deliberation and assessment (1994 - 2001), and action (2001 to present).

The current phase of subglacial lake exploration is when concrete and explicit plans will be developed to advance the exploration of subglacial lakes. This phase includes additional and improved reconnaissance to characterize Lake Vostok and provision of more detailed surveys of other lakes under the East Antarctic Ice Sheet. The formation of the Group of Specialists is an important step in advancing subglacial lake exploration.

The principal scientific goals to be addressed by subglacial lake exploration are:

The following requirements are recognized as essential for the successful implementation of a subglacial lake exploration programme:

  1. It must be internationally coordinated.
  2. It must be multi- and interdisciplinary in scope.
  3. Non-contaminating technologies and minimum disturbance must be fundamental considerations in programme design and execution.
  4. The ultimate goal must be lake entry and sampling to ensure the greatest scientific return on investment.
  5. The best opportunity for attainment of important interdisciplinary scientific objectives is the study of larger lakes, therefore Lake Vostok must be the ultimate target of a subglacial programme.

To ensure continued progress the following actions are recommended:

  1. Recognizing the international setting of the lake and the ambitious scope of the scientific programme:
    • that SCAR create a Group of Specialists on Subglacial Lakes to provide interim guidance on science issues and
    • that the Group of Specialists recommend mechanisms for the international coordination of a subglacial lake exploration programme.
  2. Recognizing the substantial resources and the wide range of skills required to accomplish a subglacial exploration programme, it is recommended:
    • that SCAR encourage individual scientists to develop a consensus among colleagues regarding the value of subglacial lake exploration;
    • that SCAR ask National Antarctic Programmes to gauge the interest of their respective countries in implementing an international subglacial lake exploration programme, and
    • that SCAR ask National Antarctic Programmes to encourage and support corollary studies to provide the information necessary for developing and implementing a subglacial lake exploration programme.
  3. Recognizing the technological and logistical challenges to be overcome, it is recommended:
    • that SCAR ask the Council of Managers of National Antarctic Programmes (COMNAP) to convene a workshop on the technologies needed for safe, contamination-free lake entry; sample retrieval; and logistics and
    • that SCAR ask COMNAP to facilitate development of an international implementation plan emphasizing shared logistics and technology development.

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Progress toward Subglacial Lake Exploration

It was agreed that the original goals of the Cambridge workshop were valid, comprehensive, and well-drawn. It was also considered appropriate to review the scientific objectives of the various disciplines to establish if additional deliberations and information were needed for further development of the science, management, logistics, and implementation plans.

Life Under the Ice

Even though no samples have been recovered from subglacial lakes, our understanding of the potential for life in subglacial lakes has been improved by modelling the physical and chemical environment that may be expected in the lakes, by analyzing accreted lake ice, and by studying analogous settings elsewhere. Progress in predicting the possible forms of life in subglacial lakes has primarily relied on the analysis of accretion ice recovered from the Vostok ice core.

Study of the geochemistry of accreted lake ice melt water has been used to infer the possible chemistries of Lake Vostok water, in particular, whether the lake water is fresh or saline and whether free dissolved oxygen is present. Estimates of the nutrient and energy sources needed to sustain an indigenous biological assemblage are now being made. These data are important in understanding the trophic state of the lake, the possible density of microbes, and the range of organism types that may reside in the lake.

Physical and Chemical Environment

Recent advances in understanding and predicting the physical and chemical environment of the lakes based on modelling efforts have set boundary conditions for various lake attributes. Until actual lake penetration, modelling will be the primary mechanism for predicting lake chemical and physical conditions.

  1. Boundaries on the chemistry and biology of Lake Vostok have been predicted by modelling;
  2. A gas hydrate model suggests substantial amounts of gas hydrate will reach the lake from the overlying glacial ice and equilibrate with the lake water.
  3. An oxygen gas hydrate model is being developed that includes a metabolic sink for oxygen as well as a glacial ice oxygen source.
  4. Low levels of 3He within accretion ice imply that hydrothermal activity is unlikely. Helium isotopic ratios in accretion ice may only reflect recent glacial meltwater.

Accreted Ice Studies

Extensive studies of the limited supplies of accreted ice continue to provide insights into the possible chemistry of lake water and the presence and type of organisms that might be expected to be present in subglacial lakes. Extrapolation to lake water properties and possible biological residents have inherent problems but currently remain, the only "window" into the lakes. Results to date include:

  1. The large ice crystal structure and abnormal grain growth creates low porosity that in turn restricts the infusion of fluids into the crystal lattice. This implies that fluids at grain boundaries may not be representative of chemical impurities in the larger mass of ice and should be used with caution to predict lake water composition.
  2. A range of microbes has been detected in accreted ice, bacterial diversity is low, and the DNA detected is typical of modern DNA.
  3. Models predict that active microbial assemblages should be able to exist in veins between ice grains.
  4. Molecular biological studies of accreted ice suggest that there are few if any microbes in accreted ice. Most microbes detected so far can be related to contamination.
  5. Recent studies utilizing ultra-clean technology imply that bacterial densities reported previously were overestimated by perhaps an order of magnitude.
  6. A number of viruses have been observed in both glacial and accretion ice. These viruses show a variety of unusual morphologies. DNA studies are underway to identify the origins of viral particles.
  7. Microbes associated with accreted ice particles most likely migrated through the ice and entered the surface waters of the lake in meltwater being quickly incorporated in the accretion process before the meltwater mixed with deeper lake water.
  8. Molecular biology studies identified a strain of bacteria whose DNA is similar to thermophilic bacteria suggesting the possible presence of hydrothermal activity.

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Analogue Environments

In the absence of actual samples from the lakes, studies of analogue locations in the cryosphere worldwide lend clues to what might be expected in subglacial lakes:

  1. Life focused in ice inclusions was described in 1998;
  2. A paper has been published on subglacial microbes in Arctic and Alpine glaciers;
  3. Japanese and Italian researchers have studied Himalayan ice microbes;
  4. A paper has been published on permafrost microbes that inhabit and grow in sub-zero environments; and
  5. A recent (July 2001) NSF - OPP workshop entitled "Life in Ancient Ice" discussed the possibilities of life at sub-zero temperatures (see http://salegos-scar.montana.edu/).

Climatic and Tectonic Evolution of Antarctica

Recent detailed analysis of aero-surveys of subglacial lakes has greatly increased our knowledge of the distribution and morphology of subglacial lakes. Advances have been made in inferring lake physiography and advancing our understanding of the glaciological setting and ice dynamics of the East Antarctic Ice Sheet. A major geophysical site survey of Lake Vostok in the 2000 - 01 field season acquired gravity and magnetic data using laser and ice penetrating radar (NSF - OPP). The Russian Antarctic Expedition has conducted extensive surface radar surveys providing detailed mapping of the western ice grounding line and improved understanding of lake depth from seismic survey results.

  1. new estimates of the residence time for the lake water (16,000 - 20,000 years) have been based on surface measurements of velocities (3m/yr) and analysis of the structures within the ice penetrating radar;
  2. the long wavelength gravity field and the distinct structures on either side of the lake has defined the tectonic setting of the lake as the extensional reactivation of an ancient thrust system; and
  3. the absence of circular magnetic anomalies around Lake Vostok and the low values of 3He in the accreted ice indicated the absence of recent volcanic mantle-derived activity within the lake basin.

Preliminary Scientific "Needs" Analysis

The Group decided that the next step in developing a plan for subglacial lake exploration was to define better the scientific objectives for subglacial lake exploration by:

  1. prioritizing the scientific objectives;
  2. reviewing the technologies needed to accomplish the objectives including sample requirements;
  3. assessing the adequacy of sampling technologies needed to determine the variables to be measured;
  4. determining the stage of exploration in which each objective could realistically be accomplished; and
  5. development of a time line for such a plan.

The Group emphasized that the plan, while phased, is not a linear progression of steps, one leading to the next, but must be a complex interplay of parallel developments that converge at critical milestones to achieve the programmatic goals and objectives.

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Life Under the Ice

In the short term, objectives related to detection and characterization of life in subglacial lakes must rely on inferences from the analysis of accretion ice. To date these results are ambiguous and controversial. Thus it was agreed that the scientific justification was adequate to encourage the return and distribution of existing ice cores archived at Vostok Station and that, if technically feasible and environmentally sound, additional coring in the existing Vostok bore hole was warranted and welcomed. It was also suggested, based on recent surveys, that accreted ice might be cored downstream of Lake Vostok.

Biological and Geochemical Techniques

The accreted ice studies have demonstrated the need for sophisticated decontamination and contamination controls to ensure ultra-clean sampling particularly where drill fluids are involved. Ultra-low dissolved organic carbon (DOC) water is needed in any washing process and certain commercial products are not sufficiently low in DOC. Clean protocols are needed alongside rigorous checks (controls at each stage). Oligotrophic culturing/maintenance are needed to optimize culturing success. Existing work has shown considerable heterogeneity in microbial distributions over even small distances so that small samples may not be representative. More realistic partition coefficients are needed to calculate lake chemistry, taking into account the possible incorporation of water during the accretion process in a manner analogous to frazil ice formation.

Methodologies for Biological Studies

This review of proposed technologies is ordered by priority and would be implemented once clean drilling technologies are available.

  1. In situ observatories - These would acquire a time series of basic measurements. Sensors would be located at various depths throughout the water column and would be deployed in the deepest section.
  2. Water sample return - If only a small volume will be retrieved initially, in situ filtering will be needed using an ultra-filter to ensure adequate recovery of sample for DNA and other particulate matter analyses.
  3. Sediment sample return - Shallow surface cores will be needed to quantify the biological communities and the basic processes of biogeochemical cycling. Longer cores will be necessary to establish the history of lake evolution and for palaeoclimate studies.

Clean Techniques

One essential aspect of subglacial lake exploration is critical testing, verification and monitoring for potential contamination during all phases of the scientific programme. Stewardship issues include providing the maximum possible protection of subglacial lake environments by ensuring minimal alteration or change due to the planned scientific studies. It is essential that uncompromised samples be provided for study and that the presence of human-made devices does not bias the observations collected.

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Preliminary Technological "Needs" Analysis

The Group agreed that the "phased" stages of exploration do not necessarily imply a sequential set of activities but will most effectively involve a series of activities being conducted in parallel, with each activity, or group of activities, having its own time line that would most likely overlap with other related or supporting activities.

Some technologies are already in place and can be used immediately for planning purposes if the financial and logistical support is available. Other technologies will require significant development efforts.

Existing ice drilling techniques appear to be capable of penetrating 4+ km of ice in low temperature and high pressure regimes. Ice drilling must be able to do so with minimal and/or acceptable levels of contamination.

Operational sensors that could be deployed within the actual lake water exist for some of the more fundamental properties whereas more complex sensor arrays will require development. Initial discussions suggest that standard oceanographic sensor arrays for pressure, salinity, temperature conductivity, transmissometry (particle detectors), fluorescence detection, and current velocity have been developed to meet similar operational requirements of temperature and pressure. More experimental sensor arrays would need to be developed for the detection of other dissolved gases (H2S, CH4, N2O, N2, Ar) major anions and cations, and bioreactive redox couples such as ammonium and dissolved manganese.

Sample recovery bystandard oceanographic techniques for remote collection using water sampling bottles and sediment retrieval by coring devices may be compatible with subglacial environments. Other specialized techniques may need to be developed.

Accelerated Lake Entry

The information provided on drilling technologies suggests that, with appropriate funding, "clean" entry into a lake could be accomplished in the near future. If the technology for entry could be tested and proven effective for the field requirements of East Antarctica it might be reasonable to penetrate multiple lakes to install in situ sensor arrays to measure basic lake water properties. A first entry would not include sample retrieval so could be considerably less complex and would minimize the environmental issues that had to be addressed.

Concluding Remarks

The initial deliberations by the Group of Specialists and this first report set the stage for more detailed and exhaustive consideration of a wide range of issues associated with developing a plan for subglacial lake exploration. The Group emphasized that these deliberations build on the conclusions and recommendations provided by the scientific community in the various workshop reports, particularly the 1999 Cambridge Report. While the materials in this report reflect the opinions of the Group, they are intended to stimulate discussions and spur action. A summary of the science and technological milestones is provided in the Table. This is seen as a preliminary assessment that will be refined and improved in future Group meetings. The Group also recognizes that the model of developing milestones will need to be followed for at least two additional components: programme management and logistical planning and coordination. A similar approach, using the time frames provided will produce an interlocking set of action items that can serve as a blueprint for implementing a subglacial lake exploration programme.

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Scientific and technological milestones for the development and implementation of a subglacial lake exploration programme.

Timeframe Short (0 - 3 years) - Pre-Lake Entry and Survey

Scientific Milestones Technological Milestones
1. Identification of a lead nation or at a minimum, the formation of an interim planning group charged with conducting a Strategic Environmental Assessment (SEA) of the entire programme. 1. Identification of a lead nation or at a minimum, the formation of an interim planning group charged with conducting a Strategic Environmental Assessment (SEA) of the entire programme.
2. Make funds and access to field logistics available to conduct surveys. 2. Convene a meeting of experts to develop decontamination standards and methods to monitor cleanliness. Identify potential funding sources to implement these developments.
3. Convene a meeting of experts to develop decontamination standards and develop methods to monitor cleanliness. Examine the availability of funds to implement these developments. 3. Convene a meeting of experts to evaluate existing ice drilling technologies, assess the need for adaptation to subglacial lake environments and access restrictions, and develop a detailed needs analysis to provide the ice drilling platform, technology and infrastructure.
4. Make funds available to develop clean methodologies, cleanliness testing methods (verification), and development of the infrastructure to handle and process samples in appropriately clean conditions to control and minimize contamination of samples with foreign materials. 4. Provide funds to develop the subglacial lake ice drilling platform and equipment infrastructure including testing in analogue settings, refining operating protocols including the implementation of clean standards.
5. Availability of funds to develop the next generation of assays and detection methodologies for extremophiles. 5. Convene a meeting of experts to assess the status of current technologies and compatibility with subglacial lake environments and access restrictions and provide plans for adapting the technologies as needed. Target indicators would be a relatively simple set of parameters currently measured on oceanographic and buoys - temperature, pressure, salinity (conductivity), particulates, fluorescence, nutrients, and dissolved oxygen.
6. Convene a meeting of experts to assess the status of current technologies and compatibility with subglacial lake environments and access restrictions and provide plans for adapting the technologies as needed. Target indicators would be a relatively simple set of parameters currently measured on oceanographic moorings and buoys &endash; temperature, pressure, salinity (conductivity), particulates, fluorescence, nutrients, and dissolved oxygen. Sediment penetrometer/shear vane and geothermal heat flow detectors should also be considered. 6. Make funds available to develop observatory concepts and produce the equipment that will be deployed in the lakes.
7. Make accreted ice samples available and provide funds to perform analyses in support of biological and geochemical objectives. 7. Convene a meeting of experts to develop a detailed and specific plan for accelerated lake entry.
8. Availability of funds to support modelling of the subglacial lake system from local to regional spatial scales and recent to geological time scales.
9. Convene a meeting of experts to develop a long term plan for palaeoclimate and geological studies of subglacial lakes.

Timeframe Medium (3 - 6 years) - Lake Entry, Observatory Deployment

Scientific Milestones Technological Milestones
10.

Make funds available for development and feasibility testing of sensors and remote detect ion techniques for geochemistry and biology. Target indicators particulates, nutrients (N, P), DOC, bioparticles, bioreactive redox couples, microbes, and dissolved gases (CH4, CO2, H2S, N2O, Ar, O2).

 8. Make funds available to begin the field operations for drilling and lake entry (The Group recognizes that the international management structure and plan must be in place to proceed with on the ground operations - these needs will be addressed in separate deliberations).
11. Convene a meeting of experts to develop rigorous sample handling protocols base on experiences form Cape Roberts and the Ocean Drilling Project. 9. Convene a meeting of experts to develop a detailed assessment and implementation plan for lake entry and sample retrieval.
12. Make funds available to develop methodologies to determine the rates of critical biological processes. 10. Convene a meeting of experts to assess technologies and develop a detailed implementation plan for lake entry and long geological core retrieval.

Timeframe Long (6 - 9 years) - Lake Entry, Critical Sample Retrieval

Scientific Milestones Technological Milestones
13. Convene a meeting of experts to develop a long term plan for sustained presence in the lake. 11. Convene a meeting of experts to develop a long term plan for sustained presence in the lakes.
12. Provide the funds and logistical support to implement the lake entry and initial sample retrieval plan.
13. Convene a meeting of experts to develop a decommissioning plan for the drill sites.

Timeframe Very Long (9+ years) - Lake Entry, Long Core Retrieval

Scientific Milestones Technological Milestones
14. Make funds available and field resources to implement the palaeoclimate and geological sampling and analysis programmes. 14. Make funds available and field resources to implement the plan for lake entry and long core retrieval, processing and analysis.