Browsing by Author "Royston-Bishop, George"

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Biological materials in ice cores
(2006) Priscu, John C.; Christner, Brent C.; Foreman, Christine M.; Royston-Bishop, George
Limnological conditions in subglacial Lake Vostok, Antarctica
(2006-11) Christner, Brent C.; Royston-Bishop, George; Foreman, Christine M.; Arnold, Brianna R.; Tranter, Martyn; Welch, Kathleen A.; Lyons, W. Berry; Tsapin, Alexandre I.; Studinger, Michael; Priscu, John C.
Subglacial Lake Vostok is located ~4 km beneath the surface of the East Antarctic Ice Sheet and has been isolated from the atmosphere for >15 million yr. Concerns for environmental protection have prevented direct sampling of the lake water thus far. However, an ice core has been retrieved from above the lake in which the bottom ~85 m represents lake water that has accreted (i.e., frozen) to the bottom of the ice sheet. We measured selected constituents within the accretion ice core to predict geomicrobiological conditions within the surface waters of the lake. Bacterial density is two- to sevenfold higher in accretion ice than the overlying glacial ice, implying that Lake Vostok is a source of bacterial carbon beneath the ice sheet. Phylogenetic analysis of amplified small subunit ribosomal ribonucleic acid (rRNA) gene sequences in accretion ice formed over a deep portion of the lake revealed phylotypes that classify within the β-, y-, and δ-Proteobacteria. Cellular, major ion, and dissolved organic carbon levels all decreased with depth in the accretion ice (depth is a proxy for increasing distance from the shoreline), implying a greater potential for biological activity in the shallow shoreline waters of the lake. Although the exact nature of the biology within Lake Vostok awaits direct sampling of the lake water, our data from the accretion ice support the working hypothesis that a sustained microbial ecosystem is present in this subglacial lake environment, despite high pressure, constant cold, low nutrient input, potentially high oxygen concentrations, and an absence of sunlight.
Source of Lake Vostok Cations Constrained with Strontium Isotopes
(2016-08) Lyons, Berry W.; Welch, Kathleen A.; Priscu, John C.; Tranter, Martyn; Royston-Bishop, George
Lake Vostok is the largest sub-glacial lake in Antarctica. The primary source of our current knowledge regarding the geochemistry and biology of the lake comes from the analysis of refrozen lake water associated with ice core drilling. Several sources of dissolved ions and particulate matter to the lake have been proposed, including materials from the melted glacier ice, the weathering of underlying geological materials, hydrothermal activity and underlying, ancient evaporitic deposits. A sample of Lake Vostok Type 1 accretion ice has been analyzed for its 87Sr/86Sr signature as well as its major cation and anion and Sr concentrations. The strontium isotope ratio of 0.71655 and the Ca/Sr ratio in the sample strongly indicate that the major source of the Sr is from aluminosilicate minerals from the continental crust. These data imply that at least a portion of the other cations in the Type 1 ice also are derived from continental crustal materials and not hydrothermal activity, the melted glacier ice, or evaporitic sources.