鉄酸化物から溶けた海洋有機炭素の地質史
Nir Galili1,2, Stefano M Bernasconi3, Alon Nissan4,5
1Geological Institute, Department of Earth and Planetary Sciences, ETH Zurich, Zurich, Switzerland. ngalili@ethz.ch.
Nature
|August 13, 2025
まとめ
海洋溶解有機炭素 (DOC) レベルは地質学的な時間とともに大きく変動した. この研究は古代のDOC濃度を再構築し,海洋化学,酸素化,複雑な海洋生物の進化の間のリンクを明らかにします.
科学分野:
- 地化学
- 古代海洋学
- 海洋生物学
背景:
- 溶けた有機炭素 (DOC) は,海洋生態系と大気中のCO2を調節する主要な炭素貯蔵庫です.
- 海洋DOCの地質史を理解することは,過去の生態学的および生地化学的プロセスを再構築するために不可欠です.
- 古代の海洋DOCの動態に関する現在の知識は限られている.
研究 の 目的:
- 過去の海洋溶解有機炭素 (DOC) のシグネチャーを再構築するためのプロキシを開発し,検証する.
- 海洋のDOC濃度とその同位体組成を長期的にデータに基づいた再構築を行う.
- 海洋のCODの変化と海洋の酸素化と生命の進化を結びつけるため
主な方法:
- 過去のDOCの代理として,鉄オオイド内の共同降水した有機炭素を使用した.
- 16億5千万年前の 鉄の卵子を含む26の海洋構造を分析した
- 地質時間における DOC濃度と13C組成を再構築した.
主要な成果:
- 海洋のDOC濃度は,古プロテロゾーイク時代に現代のレベルに近い.
- DOCはネオプロテロゾイク時代に90~99%減少し,カンブリア時代に急激に増加した.
- 現代のDOCは,プロテロゾーイクと比較して13C濃度が高く,おそらく生物学的革新によるものである.
結論:
- DOCのダイナミクスは,生物の複雑性と酸素化に関連した3つの異なる海洋状態を反映しています.
- 複雑な生命の進化と 海洋の酸素供給と 炭素の循環は 相互に関連しています
- 発見は16億5千万年以上に渡って 海洋生態系と生地化学の進化を 洞察するものです
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