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大気中のO2濃度に関するプレイストセンの氷核記録
D A Stolper1, M L Bender2, G B Dreyfus3
1Department of Geosciences, Princeton University, Princeton, NJ 08544, USA.
まとめ
大気中の酸素 (O2) レベルは 過去80万年の間に 0.7%減少しました この発見は 古代の空気のサンプルを基に 酸素の吸収が 源を超え 地球の生地化学的サイクルに 影響を及ぼすことを示唆しています
科学分野:
- 地球科学
- 古代気候学
- 生地化学
背景:
- 過去の大気中の酸素部分圧 (Po2) を再構築することは,地球と生命の共同進化を理解するために重要である.
- 既存のPo2再構築はしばしば重大な不一致を示し,より堅固な方法の必要性を強調しています.
研究 の 目的:
- 大気中のPO2の信頼性の高い長期記録を 新しいプロキシを用いて作成する.
- 過去100万年の酸素濃度と 生物地球化学のサイクルと 気候の関係を調べるため
主な方法:
- 南極の氷の核に閉じ込められた空気泡のO2/N2比の分析.
- 有機炭素の埋葬とピライトの気象化を含む酸素シンクと源のモデリング.
主要な成果:
- 大気中のPo2の記録は 800,000年連続して生成されました
- この期間中,PO2は約0. 7% (7分) 減少した.
- 酸素シンクは常に約2%の供給量を上回っている.
結論:
- 観測されたPO2の減少は,ネオゲン冷却またはプレイストセンの侵食によって引き起こされる可能性のある炭素とピライトの流れの変化に関連しています.
- 同じ期間の安定した大気中の二酸化炭素部分圧力 (Pco2) は,Po2の減少にもかかわらず,気候調節におけるシリケート気象フィードバックの役割を支持しています.
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