プランクトンデルタ13Cの緯度変動:過去の海洋におけるCO2と生産性への影響
G H Rau1, T Takahashi, D J Des Marais
1Institute of Marine Sciences, University of California, Santa Cruz 95064, USA.
Nature
|October 12, 1989
まとめ
マリン・バイオータ (海洋生物)
科学分野:
- パレオセアノグラフィー
- マリン・バイオジオケミストリー
- イソトープ地球化学 イソトープ地球化学
背景:
- 海洋有機物質の安定した炭素同位体組成は,地質的な時間とともに変化します.
- この変動は,海洋生物による炭素吸収分数の変化を反映している.
- 過去の研究では,白期の堆積物や南極のプランクトンの低い13C/12C比が,大気中のCO2濃度が高いことと関連づけられていた.
研究 の 目的:
- 高緯度海洋環境における二酸化炭素の利用可能性と炭素同位体の枯渇との関係を調査する.
- クレタ紀の海洋有機物質における13Cの減少の原因を再評価する.
主な方法:
- 海洋有機物質の安定炭素同位体組成 (13C/12C) の分析.
- 表面水における二酸化炭素部分圧力 (pCO2) の測定.
- 溶解した無機炭素 (DIC) の濃度の計算は,温度とpCO2.2に基づいて行われます.
主要な成果:
- 高緯度の同位体枯渇は,現在の大気値より低いpCO2レベルで発生します.
- 高緯度の低温はCO2の溶解性を高め,溶解CO2濃度が高くなります.
- 南極の地表水は,赤道水よりも溶けたCO2濃度が最大2.5倍高い可能性があります.
- 800マイクロ大気を超えるクレタセアスの海洋のpCO2レベルは,観測されたプランクトン13Cの枯渇を説明するために計算されています.
結論:
- 高濃度の溶けたCO2は必ずしも高pCO2ではないが,高緯度プランクトンにおける炭素同位体の枯渇を誘発する.
- クレタケウスの海のpCO2レベルは,観測された炭素同位体データを説明するために,以前に想定されたより大幅に高かった可能性が高い.
- 温度に依存するCO2溶解性は,炭素同位体記録から過去の海洋CO2レベルを解釈する上で重要な役割を果たします.
キーワード:
NASA Center ARCは,NASAセンターのARCとして運営されています.NASAの規律 エキゾバイオロジーNASAの規律規則52-30号についてNASA エクゾバイオロジープログラムさらに関連する動画
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