アーカイアンにおけるエアロビック呼吸
1Department of Paleobiolgoy, Smithsonian Institution, Washington, DC 20560, USA.
Nature
|November 1, 1990
まとめ
初期の地球 初期の地球
科学分野:
- 地質化学 地質化学
- 大気科学 大気科学
- パレオントロジー・パレオントロジー
背景:
- アーカイア期 (3,8億~2,500億年前) の大気は,無酸素であったと広く考えられている.
- 溶けた鉄 (Fe(II)) の酸化とメタンの酸化のような酸素の吸収は,無酸素を維持するのに不十分でした.
- アルカイア期初次生産性の低評価は,大気中の酸素の調節に関する既存のモデルに異議を唱える.
研究 の 目的:
- 古代エオンにおける初期の有酸素呼吸の妥当性を調査する.
- プロテロゾイク以前の大気中の酸素レベルを調節するための代替メカニズムを提案する.
主な方法:
- アルカイア時代の岩石に保存された有機炭素を基に酸素吸収の再評価.
- アノキシアを維持するための鉄とメタンの酸化要求のモデリング.
- エアロビック呼吸の初期の発展を仮説化する.
主要な成果:
- 無酸素状態を維持するには,非現実的に高い鉄堆積量やメタンの酸化が必要になります.
- 最小限の初等生産性であっても,酸素の蓄積のためのシンクが不十分であることを示唆しています.
- この研究は,安定した低酸素大気 (0.2-0.4%) が必要であると示唆しています.
結論:
- エアロビック呼吸は,おそらくアーカイア初期に進化した.
- 初期の有酸素呼吸は,過度の大気中の酸素の蓄積を防止しました.
- これは,厳格に無毒なアーカイアの大気という伝統的な見解に異議を唱える.
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