河川が海洋ボロンイソトープに及ぼす影響と,過去の海洋pHを再構築するための影響
D Lemarchand1, J Gaillardet, E Lewin
1Laboratoire de Géochimie et Cosmochimie, Institut de Physique du globe de Paris. lemarcha@ipgp.jussieu.fr
Nature
|January 5, 2001
まとめ
海洋のpHは大気中のCO2に敏感です. 海殻のボロンイソトープはpHを推定できますが,海水のボロン予算を理解する必要があります. この研究では,河川の流れを使用して海洋ボロン予算のバランスをとり,過去のpH再構築に影響を与えています.
科学分野:
- 地質化学 地質化学
- 海洋学 海洋学とは
- 古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは
背景:
- 海洋のpHは大気中の二酸化炭素濃度の重要な指標である.
- 過去の海洋のpHを再構築するには,海洋炭酸塩のボロンイソトープ (デルタ11B) のような代理物に依存します.
- 正確なpH再構築には,世界の海洋ボロン同位体予算を理解することが必要である.
研究 の 目的:
- 河川のボロン流を組み込むことにより,海洋ボロン同位体予算を制限する.
- 過去1億2000万年の海水デルタ11Bの組成を再構築する.
- フォラミニフェラルデルタ11B記録におけるボロンイソトープ予算の変化の影響を評価する.
主な方法:
- 22の主要な世界の河川からのデルタ11B測定を用いて,河川のボロン流量を推定した.
- グローバルな海洋ボロン同位体予算モデルに統合された河川ボロン流れ.
- 海水デルタ11Bの成分を派生させ,公表されたホルマニフェラルデルタ11Bのデータと比較した.
主要な成果:
- 河川のボロン流を組み込むことで,海洋のボロン同位体予算を成功裏に均衡させました.
- 復元された海水デルタ11Bの組成は,ケノゾーイクにおけるフォラミニフェラルデルタ11Bの記録と一致している.
- Foraminiferal delta11Bの記録は,pHの変化だけでなく,海洋ボロン同位体予算の変化を反映している可能性があります.
結論:
- 河川のボロン流は,海洋のボロン同位体予算の重要な構成要素です.
- この研究は,過去の海洋pHのより正確な再構築のための枠組みを提供します.
- ボロンイソトープ予算の影響の可能性を考慮して,ケノゾイク海のpH記録の再評価が必要である.
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