Environmental geochemical and biological features of Antarctic oases

• MATSUMOTO G. I.

  Department of Environmental Information Science, School of Social Information Studies, Otsuma Women's University

Abstract

Distinctive geochemical and biological features of Antarctic oases are discussed from an environmental viewpoint. The increase of lake water level and the decrease of lake ice thickness in the McMurdo Oasis, and the increasing numbers of population and colonies of native vascular plants in the Argentine Islands of the Antarctic Peninsula region probably reflect global warming by human activity. Distributions of organisms in Antarctica are controlled mainly by extremely low air temperatures. Cryptoendolithic microbial communities distributed in the nearsurface layers of porous rocks of the McMurdo Oasis are the best adapted form for the extremely cold and dry environment. Extraordinary high pH (>9) and dissolved oxygen concentrations (>20ml/l) are often detected in perennially ice-covered lakes and ponds. Extremely high total organic carbon (>20mgC/l) correlated with chloride ion content is found in the bottom waters of saline lakes. Chlorophyll-a data in Lake Vanda of the McMurdo Oasis reveal that the lake has the highest Secchi transparency, greater than 45m, the clearest water in the world. Long-chain (>C_<19>) n-alkanes and n-alkanoic acids, and C_<29> sterols (e.g., 24-ethylcholest-5-en-3β-ol), which are believed to be characteristic of vascular plants, are often the predominant compounds in lake sediments and soils, in spite of the absence of vascular plants in the oases. These compounds are probably derived from microalgae and/or cyanobacteria. Novel long-chain (C_<20>-C_<33>) anteiso-alkanes and anteiso-alkanoic acids found in cryptoendolithic microbial communities may be attributed to certain bacteria in unique microbial communities. The monitoring of lake water level, lake ice thickness in the McMurdo Oasis, and the date of total surface ice-cover formation of lakes in the Syowa Oasis, such as Lake O-ike, as well as the changes in biological distributions, such as vascular plants, mosses and/or lichens in Antarctica are important to estimate environmental changes, in particular global warming.

Journal

• Proc. Natl. Inst. Polar Res., Spec. Issue

  Proc. Natl. Inst. Polar Res., Spec. Issue 52 230-250, 1998

  National Institute of Polar Research

Details

• CRID: 1570291226860688768
• NII Article ID: 110000010413
• NII Book ID: AA00733561
• ISSN: 03860744
• Text Lang: en
• Data Source:
  • CiNii Articles