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  • 1
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    The Antarctic dry valley lakes: Relevance to Mars (1989)
    In:  CASI
    Details
    Publikationsdatum: 2013-08-31
    Beschreibung: The similarity of the early environments of Mars and Earth, and the biological evolution which occurred on early Earth, motivates exobiologists to seriously consider the possiblity of an early Martian biota. Environments are being identified which could contain Martian life and areas which may presently contain evidence of this former life. Sediments which were thought to be deposited in large ice-covered lakes are present on Mars. Such localities were identified within some of the canyons of the Valles Marineris and more recently in the ancient terrain in the Southern Hemisphere. Perennially ice-covered Antarctic lakes are being studied in order to develop quantitative models that relate environmental factors to the nature of the biological community and sediment forming processes. These models will be applied to the Martian paleolakes to establish the scientific rationale for the exobiological study of ancient Martian sediments.
    Schlagwort(e): GEOPHYSICS
    Materialart: Exobiology and Future Mars Missions; p 62
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
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    Early Martian environments - The antarctic and other terrestrial analogs (1989)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-19
    Beschreibung: The comparability of the early environments of Mars and earth, and the biological evolution which occurred on early earth, motivates serious consideration of the possibility of an early Martian biota. Environments which could have contained this early Martian life and which may presently contain evidence of this former life include aquatic, ice, soil, and rock habitats. Several analogs of these potential early Martian environments, which can provide useful information in searching for extinct life on Mars, are currently available for study on earth. These terrestrial analogs include the perennially ice-covered lakes and sandstone rocks in the polar deserts of Antarctica, surface of snowfields and glaciers, desert soils, geothermal springs, and deep subsurface environments.
    Schlagwort(e): SPACE BIOLOGY
    Materialart: Planetary Biology and Origins of Life, 20th, 21st, and 23rd, Espoo, Finland, July 18-29, 1988) Advances in Space Research (ISSN 0273-1177); 147-153
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 3
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    Perennially ice-covered Lake Hoare, Antarctica: physical environment, biology and sedimentation (1989)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: Lake Hoare (77 degrees 38' S, 162 degrees 53' E) is a perennially ice-covered lake at the eastern end of Taylor Valley in southern Victoria Land, Antarctica. The environment of this lake is controlled by the relatively thick ice cover (3-5 m) which eliminates wind generated currents, restricts gas exchange and sediment deposition, and reduces light penetration. The ice cover is in turn largely controlled by the extreme seasonality of Antarctica and local climate. Lake Hoare and other dry valley lakes may be sensitive indicators of short term (〈 100 yr) climatic and/or anthropogenic changes in the dry valleys since the onset of intensive exploration over 30 years ago. The time constants for turnover of the water column and lake ice are 50 and 10 years, respectively. The turnover time for atmospheric gases in the lake is 30-60 years. Therefore, the lake environment responds to changes on a 10-100 year timescale. Because the ice cover has a controlling influence on the lake (e.g. light penetration, gas content of water, and sediment deposition), it is probable that small changes in ice ablation, sediment loading on the ice cover, or glacial meltwater (or groundwater) inflow will affect ice cover dynamics and will have a major impact on the lake environment and biota.
    Schlagwort(e): Exobiology
    Materialart: Hydrobiologia (ISSN 0018-8158); 172; 305-20
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 4
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    Oxygen budget of a perennially ice-covered Antarctic lake (1986)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-12
    Beschreibung: A bulk O2 budget for Lake Hoare, Antarctica, is presented. Five years of seasonal data show the lake to be persistently supersaturated with O2. Oxygen is carried into the lake in glacial meltstreams and is left behind when this water is removed as ice by ablation and sublimation. A diffusive loss of O2 from the lake through the summer moat is suggested. Measured values of the total O2 in the water column indicate that the time scale of O2 turnover is much longer than a year. Based on these results, it is suggested that the amount of O2 in the water does not change significantly throughout the year and that the lake is also supersaturated with N2.
    Schlagwort(e): EARTH RESOURCES AND REMOTE SENSING
    Materialart: Limnology and Oceanography (ISSN 0024-3590); 31; 2 19
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 5
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    Sediment oxygen profiles in a super-oxygenated antarctic lake (1994)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-08-15
    Beschreibung: Perennially ice-covered lakes are found in the McMurdo Dry Valleys of southern Victoria Land, Antarctica. In contrast to temperate lakes that have diurnal photic periods, antarctic (and arctic) lakes have a yearly photic period. An unusual feature of the antarctic lakes is the occurrence of O2 at supersaturated levels in certain portions of the water column. Here we report the first sediment O2 profiles obtained using a microelectrode from a perennially ice-covered antarctic lake. Sediment cores collected in January and October 1987 from Lake Hoare in Taylor Valley show oxygenation down to 15, and in some cases, 25 cm. The oxygenation of sediments several centimeters below the sediment-water interface is atypical for lake sediments and may be characteristic of perennially ice-covered lakes. There is a significant difference between the observed January and October sediment O2 profiles. Several explanations may account for the difference, including seasonality. A time-dependent model is presented which tests the feasibility of a seasonal cycle resulting from the long photoperiod and benthic primary production in sediments overlain by a highly oxygenated water column.
    Schlagwort(e): Exobiology
    Materialart: Limnology and oceanography (ISSN 0024-3590); 39; 4; 839-53
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
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    Cryoconite holes on glaciers (1985)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-12
    Beschreibung: Cryoconite holes are water-filled depressions on the surface of glaciers. They contain microbial communities and may contribute to glacial wastage and biological colonization of ice-free areas.
    Schlagwort(e): GEOPHYSICS
    Materialart: BioScience (ISSN 0006-3568); 35; 499-503
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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