約1.9Gyr前までの海洋の生産性は,鉄酸化物への吸収によって制限されていました
Christian J Bjerrum1, Donald E Canfield
1Danish Center for Earth System Science, Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark. cjb@geo.geol.ku.dk
Nature
|May 10, 2002
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
- パレオセアノグラフィー
- 進化生物学の進化生物学について
背景:
- 初期の地球における酸素の生産は,海洋の栄養素,特にの供給に依存していた.
- 現代の海洋におけるの除去には,鉄酸化物への吸収が含まれます.
- 帯状鉄の形状は,過去の低硫酸塩条件下での酸化鉄の堆積が強化されたことを示唆しています.
研究 の 目的:
- 帯状鉄の形成物におけるリンと鉄の含有量を分析する.
- 古代の海洋オーソフォスファート濃度を再構築するために.
- 初期の地球における酸素生産に対するリンの利用可能性の影響を評価する.
主な方法:
- 地質学的サンプルにおけるリンと鉄の含有量の分析.
- 地化学プロキシを用いた古海洋学再構築.
- 栄養素循環のモデリングとその光合成と炭素埋葬への影響.
主要な成果:
- 32億~19億年前の海洋オートホスファート濃度は,現在の10~25%でした.
- 鉄酸化物の吸収によるリン除去の強化は,おそらくこの期間中に発生した.
- 低量のリンが利用可能で,早期の光合成と炭素埋葬を大幅に制限しました.
結論:
- 低量のリンが利用可能だったため,初期の地球では酸素の生産が制限されていた.
- この制限は,アルカイアン後期とプロテロゾーイク初期に観測された大気中の低酸素レベルに寄与しました.
- 栄養素の利用可能性は,地質学的時間尺度における惑星の酸素レベルを調節する重要な要因です.
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