HR: 0800h
AN: U31B-0301    [Abstracts]
TI: Different Behavior Of Deuterium And Oxygen 18 In The Lake Vostok Ice
AU: * Ekaykin, A A
EM: ekaykin@aari.nw.ru
AF: Institute of Low Temperature Sciences, Kita-ku, Kita 19 Nishi 8, Sapporo, 060-0819, Japan
AU: * Ekaykin, A A
EM: ekaykin@aari.nw.ru
AF: Arctic and Antarctic Research Institute, 38 Beringa st., St. Petersburg, 199397, Russian Federation
AU: Lipenkov, V Y
EM: lipenkov@aari.nw.ru
AF: Arctic and Antarctic Research Institute, 38 Beringa st., St. Petersburg, 199397, Russian Federation
AU: Petit, J R
EM: petit@lgge.obs.ujf-grenoble.fr
AF: Laboratoire de Glaciologie et Geophysique de l'Environnement, 54 rue Moliere, Grenoble, 38400, France
AU: Johnson, S J
EM: sigfus@gfy.ku.dk
AF: Niels Bohr Institute, Juliane Maries Vej 30, Copenhagen, DK-2100, Denmark
AU: Masson-Delmotte, V
EM: valerie.masson@cea.fr
AF: Laboratoire des Sciences du Climat et de l'Environnement, CE Saclay, Orme des Merisiers, Gif-sur-Yvette, 91191, France
AU: Jouzel, J
EM: jouzel@dsm-mail.saclay.cea.fr
AF: Laboratoire des Sciences du Climat et de l'Environnement, CE Saclay, Orme des Merisiers, Gif-sur-Yvette, 91191, France
AB: New isotopic (D and 18O) data from the deep Vostok ice core below 3611 m is presented. The methodological problems of data accuracy are discussed, taking into account a very low natural variability of isotopic content in the lake ice. In order to interpret the lake ice core data, a simple isotope model for lake water and ice is developed. The analyzed data demonstrates clear signature of all three processes contributing to the variability of lake ice isotopic composition: physical conditions of the ice formation, and lake water isotope variability due to glacier melt and hydrothermal water influence. Different behavior of D and 18O for certain lake ice intervals is observed, which might be related to the isotope fractionation of the both isotopes in hydrothermal circulation beneath the lake. At the same time, mean isotopic content remains nearly constant for the whole lake ice thickness yet studied, which implies overall same conditions in terms of melt-lake-hydrothermal water mixing and physical conditions of lake formation. A complete scheme of isotope water budget in lake Vostok is suggested, including an estimation of melt-water isotope content, the presence of additional (hydrothermal) water source and possibly not complete mixing of melt water with deeper lake water. The most likely value of the isotopic content of the water freezing under the glacier base in the southern part of lake Vostok is 450 ‰ for D and 58 ‰ for 18O. Other issues, including preservation of isotopic signal after diffusive smoothing, short-term isotope variability in lake ice, not-steady-state lake budget scenario and future study perspectives, are discussed.
DE: 0724 Ice cores (4932)
DE: 0726 Ice sheets
DE: 0746 Lakes (9345)
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 9310 Antarctica (4207)
SC: Union [U]
MN: 2007 Fall Meeting