南極の湖の長年のN2過飽和
R A Wharton1, C P McKay, R L Mancinelli
1Life Science Division, NASA-Ames Research Center, Moffett Field, California 94035, USA.
Nature
|January 22, 1987
まとめ
南極の湖は,生物学的活動と氷の形成を含む物理的なプロセスの両方により,高い酸素レベルを示しています. この物理的メカニズムは,水中の窒素ガス (N2) のレベルも増加させます.
科学分野:
- 地質化学 地質化学
- リムテクノロジーとは
- 大気科学 大気科学
背景:
- ホアール湖のような南極の乾燥渓谷の湖は,異常に高い溶解酸素 (O2) 濃度を示し,飽和度を上回ります.
- 以前の研究では,観察されたO2過飽和は生物学的プロセスだけでは説明できないことが示唆されていました.
- 氷の形成中のガス排除を含む物理的メカニズムは,潜在的な非生物学的O2源として仮定されました.
研究 の 目的:
- 南極の湖における他の大気ガス,特に窒素 (N2) の過飽和を調査する.
- ホアール湖のガス濃度に対する生物学的および物理的なプロセスの相対的な貢献を定量化するために.
- 凍結中のガス排除が湖水中の大気ガスを増大させるという仮説を検証する.
主な方法:
- 溶けた窒素 (N2) と酸素 (O2) の濃度の分析を様々な深さでホアール湖から採取した水サンプルで行った.
- 氷と水の界面および12メートルの深さでのN2およびO2濃度の測定.
- 測定されたガス比率 (N2:O2) と大気平衡から予想される比率の比較.
主要な成果:
- ホアール湖で初めて溶けたN2の過飽和が記録され,濃度は145%と163%に達した.
- 湖の観測されたN2:O2比 (界面で1.20,12mで1.05) は,大気平衡比 (約. 1.8) 1.8) ということでした.
- ホアール湖の純O2生産の約50%が生物学的プロセスに起因していることが示されています.
結論:
- 溶融水の凍結中のガスの物理的排除は,南極の湖でO2とN2のレベルが上昇することに大きく貢献しています.
- 生物学的生産と物理的プロセスの両方が,これらのユニークな湖の生態系のガス動態において重要な役割を果たしています.
- この発見は,永久に氷で覆われている南極の湖で大気ガスを増強する物理的メカニズムがあるという仮説を裏付けている.
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