More than 200 meters of lake ice above subglacial Lake Vostok, Antarctica

Science

Volumn 286, Issue 5447, 1999, Pages 2138-2141

  Jouzel, J ^a   Petit, J R ^b   Souchez, R ^c   Barkov, N I ^d   Lipenkov, V Ya ^d   Raynaud, D ^b   Stievenard, M ^a   Vassiliev, N I ^e   Verbeke, V ^c   Vimeux, F ^a  

^a LABORATOIRE DES SCIENCES DU CLIMAT ET DE L ENVIRONNEMENT   (France)

^b CNRS   (France)

^c Dept des Sciences de la Terre Faculté des Sciences Université de Bruxelles ^*  (Belgium)

^d ARCTIC AND ANTARCTIC RESEARCH INSTITUTE   (Russian Federation)

^e SAINT PETERSBURG MINING UNIVERSITY   (Russian Federation)

Author keywords

[No Author keywords available]

Indexed keywords

ICE;

ICE CORE; ICE THICKNESS; LACUSTRINE ENVIRONMENT; LAKE ECOSYSTEM;

ANTARCTICA; ARTICLE; CRYSTAL STRUCTURE; ELECTRIC CONDUCTIVITY; FREEZING; GAS; LAKE; PRIORITY JOURNAL;

ANTARCTICA; LAKE VOSTOCK;

EID: 0032764696     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.286.5447.2138     Document Type: Article

References (27)

1. J. R. Petit et al., Nature 399, 429 (1999). Ice coring was stopped at 3623 m, the depth reached in January 1998, which is about 120 m above the interface with subglacial Lake Vostok (4), to avoid any contamination by the drilling fluid.
2. V. Lipenkov and N. Barkov, Proceedings of the International Workshop on Lake Vostok. Lake Vostok Study: Scientific Objectives and Technical Requirements (Arctic and Antarctic Research Institute, St. Petersburg, Russia, 1998), p. 31.
3. P. Martinerie et al., J. Geophys. Res. 99, 10565 (1994).
4. 2. The Vostok drilling site (Fig. 1) is at the southern end of the lake and has a thickness of 3750 m of ice with 600 m of water below the ice. At its northern end, 200 km away, the ice is 4300 m thick and the water below is shallower. For more information see A. Kapitsa et al., Nature 381, 684 (1996); M. Siegert and J. Ridley, J. Geophys. Res. 103, 10195 (1998).
5. 2. The Vostok drilling site (Fig. 1) is at the southern end of the lake and has a thickness of 3750 m of ice with 600 m of water below the ice. At its northern end, 200 km away, the ice is 4300 m thick and the water below is shallower. For more information see A. Kapitsa et al., Nature 381, 684 (1996); M. Siegert and J. Ridley, J. Geophys. Res. 103, 10195 (1998).
6. std - 1] × 1000, where std is the standard mean ocean water reference (the same applies for δD).
7. F. Vimeux, V. Masson, J. Jouzel, M. Stievenard, J. R. Petit, Nature 398, 410 (1999).
8. 18O diagram, data points from zones I and D are (indistinguishable from those of the past 420 ky (zone C), as illustrated by the individual data points from the bottom part of zone D (Fig. 2).
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10. R. Souchez and J. Jouzel, J. Glaciol. 30, 369 (1984).
11. -1.
12. 18O relation for periods before 420 ka, because the central part of the Antarctic ice sheet and its surrounding oceans probably have not been subject to changes larger than those during the past 420 ky.
13. A numerical simulation with the use of a simple diffusion model and the assumption that pure diffusion is limited to the boundary layer at the ice-water interface is described [R. Souchez et al., Geophys. Res. Lett. 14, 599 (1987)]. This shows that a higher freezing rate will produce a weaker isotopic enrichment in the ice than that produced at equilibrium.
14. A. Salamatin, R. N. Vostretsov, J. R. Petit, V. Y. Lipenkov, N. I. Barkov, Data Glaciol. Stud. 85, 233 (1998).
15. 1 is the isotopic content of the initial liquid reservoir and f is the fraction of liquid remaining. The apparent 60% enrichment of the ice in comparison to the initial liquid is obtained when ∼30% of the reservoir has frozen. As expected from the Rayleigh model, the data both for ice and liquid samples align on the freezing slope, and such laboratory experiments were used to support the melting-refreezing theory that two of us have developed (8, 9). This experimental freezing slope is close to the theoretical value (Fig. 2).
16. The sample in the transition aligns on the straight line that is defined by the cluster of samples above (disturbed glacier ice) and below (lake ice) but has a slope (4.88) significantly higher than 3.98. We interpret this alignment as a result of a diffusion process at a sharp transition between the two types of ice, and not as a freezing effect.
17. D. Paillard, Nature 391, 378 (1998); R. Tiedeman et al., Paleoceanography 9, 619 (1994). Data suggest that there was a warmer global climate (lower continental ice volume) for the period between 2 million and 1 million years ago than for the past 1 million years.
18. D. Paillard, Nature 391, 378 (1998); R. Tiedeman et al., Paleoceanography 9, 619 (1994). Data suggest that there was a warmer global climate (lower continental ice volume) for the period between 2 million and 1 million years ago than for the past 1 million years.
19. J. Priscu et al., Science 286, 2141 (1999); D. M. Karl et al., Science 286, 2144 (1999).
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21. J. M. Tiedje, in (21), p. 19; D. C. White, in (21), p. 22.
22. J. M. Tiedje, in (21), p. 19; D. C. White, in (21), p. 22.
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24. F. Carsey, in (27), p. 21.
25. National Science Foundation Workshop-The Lake Vostok Study: A Curiosity or a Focus for Interdisciplinary Investigations, Washington, DC, 7 to 8 September 1998. See www.Ideo.columbia.edu/vostok/.
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27. This work is part of the joint project between Russia, France, and the United States to study the Vostok ice core. We are indebted to the Russian drill engineers from the St. Petersburg Mining Institute who conducted the field operations, and we thank all participants for field work and ice sampling. We acknowledge the Russian Antarctic Expeditions (RAE), the Institut Français de Recherches et Technologies Polaires (IFRTP), and the Division of Polar Programs (NSF) for logistic support. The project is supported in Russia by the Russian Ministry of Sciences; in France by the PNEDC (Programme National d'Etudes de la Dynamique du Climat) and by the Commission of European Communities (Environment Programme, ENV4-CT95-0130); and in the United States by NSF. R.S. and V.V. are grateful for the support of the Belgian Antarctic programme (Science Policy Office). We thank J. M. Barnola, J. Chappellaz, M. Delmotte, P. Duval, F. Ferron, G. Hoffmann, J. L. Jaffrezo, P. Jean-Baptiste, D. Paillard, L. Pépin, A. Salamatin, and D. Weis for helpful discussions and comments on the manuscript and T. Sowers and an anonymous reviewer for constructive criticism.