過去1億3000万年の海水化学の急速な変動
Ulrich G Wortmann1, Adina Paytan
1Geobiology Isotope Laboratory, Department of Geology, University of Toronto, Toronto, ON M5S 3B1, Canada. uli.wortmann@utoronto.ca
まとめ
海水の化学成分は,以前の考えに反して,急速に変動した. 硫黄循環モデルは,蒸発性堆積物によって引き起こされる硫酸塩レベルの変化が,地質学的硫黄同位体記録を説明することを示しています.
科学分野:
- 地質化学 地質化学
- パレオセアノグラフィー
- バイオジオケミカルサイクル
背景:
- 海水の組成は,伝統的に地質的な時間とともにゆっくりと変化すると考えられています.
- 高解像度の同位体データは,海洋化学のより急速な変動を示唆しています.
- これらの変化を理解することは,地球の歴史を解釈し,将来の気候を予測するために不可欠です.
研究 の 目的:
- 海水化学の進化に関する対立する見解を調和させるため.
- ダイナミックモデルを使用して,世界の硫黄同位体 (δ(34) S) レコードを説明します.
- 硫酸塩濃度の変化が地球システムに与える影響を調査する.
主な方法:
- グローバルな硫黄循環の非安定状態のボックスモデルを開発した.
- 海洋硫酸塩濃度の変動による影響をシミュレートした.
- 結果として得られたグローバル δ(34) S レコードを分析した.
主要な成果:
- このモデルは,長い安定期と短い急速なシフトによって特徴づけられる観測された δ(34) S レコードをうまく説明しています.
- 蒸発物の降水と溶解によって引き起こされる海洋硫酸塩濃度の変動は,主な原因として特定されています.
- 硫酸塩濃度の変化は,海洋の生産性,炭素循環,気候に影響を与えます.
結論:
- 海水の化学は,ゆっくりとした変化ではなく,急速な変動を示しています.
- 蒸発ダイナミクスは,海洋硫酸塩レベルと地球規模の硫黄循環を調節する上で重要な役割を果たします.
- これらの硫酸塩の変動は,海洋生物学,海洋生産性,そして地球温暖化に重大な影響を及ぼします.
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