Geomicrobiology of Vostok Ice: Implications for Life in Lake Vostok
|Recent studies have revealed a number of subglacial lakes beneath the Antarctic ice sheet. Lake Vostok, lying 4 km beneath the ice surface is the largest of these lakes with a surface area near 10,000 km2 and a depth exceeding 600 m. A permanent ice sheet covered the lake about 15 million years ago isolating it from the atmosphere. Geochemical and crystallographic measurements, in concert with airborne radar studies, indicate regions of frozen lakewater accreted to the bottom of the permanent ice sheet. There is evidence that the accretion ice from Lake Vostok contains microbes, implying that a microbial assemblage exists within the lake itself. This collaborative (5 institutions, 9 investigators), multidisciplinary effort will be the first to examine (i) physical stresses in deep glacial and accretion ice, (ii) the role of clathrates on gas dynamics within the lake, (iii) the origin of microbes in accretion ice, (iv) the physiological state of ice-bound microbes, (v) the geochemistry of the ice column (bulk and within veins), and (vi) living microbes in ice veins that form at triple junctions in the ice crystal matrix. Collectively, results from this study will provide new information on the deepest ice yet collected and allow boundaries to be placed on conditions within Lake Vostok. Considering the enormous financial and logistic effort that will be required to obtain uncontaminated samples from Lake Vostok, it is imperative that conditions within the overlying ice, which presumably supplies the nutrients and biological seed to the lake, be understood before any attempt is made to sample the actual lakewater. Such information will allow meaningful and hypotheses to be drawn regarding the physical, chemical and biological properties of the lake, and will provide critical background for the development and implementation of a sterile sample recovery system.|
Accretion ice does not exist under hydrostatic
conditions. After freezing onto the ice sheet, it undergoes
gradual but significant increases in shear resulting in substantial development of
dislocations within the lattice structure, reorientation of the crystallographic texture,
and stress-induced effects on triple junctions.
Web Page is Maintained by Renee Christner