沈殿物の炭素酸化率が低いため,太平洋の中間水域で溶けた酸素が増えた
L D Stott1, W Berelson, R Douglas
1Department of Earth Sciences, University of Southern California, Los Angeles 90089, USA. stott@usc.edu
Nature
|October 3, 2000
まとめ
海洋溶解酸素のレベルは,1970年代以降上昇しており,これは海底堆積物の変化によって示されています. この酸素濃度の上昇は,北太平洋の気候変化が海洋の生産性に影響を与えていることと関連しています.
科学分野:
- 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
- 海洋地質学 海洋地質学
背景:
- 海の溶けた酸素濃度は,過去の気候の不安定さと相関しています.
- プレイストセンの氷河期には,今日よりも太平洋の中間水域に溶けた酸素が多かった.
- 北東太平洋の盆地では,現在,層状の堆積物が示されており,換気量が低下したため酸素濃度が低いことを示しています.
研究 の 目的:
- 北東太平洋の溶けた酸素濃度の最近の変化を調査するため.
- 気候変動,海洋の生産性,そしてベンシック酸素レベルとの関係を理解する.
主な方法:
- 太平洋盆地における堆積物の種類 (バイオターベート vs. ラミネート) の分析.
- 炭酸酸化率を推論するために,ベンシックフォラミニフェルの炭素同位体組成を用いる.
- 沈殿物の変化と北太平洋の気候データとの相関関係,上流と海面温度を含む.
主要な成果:
- 1970年代後半から北東太平洋で観察されたバイオターバテッドの堆積物に戻る.
- 沈殿物の炭素酸化率が2倍に低下し,溶けた酸素が1リットルあたり15〜20ミクロモール増加する.
- この変化は,上流の20〜30%の減少と,北太平洋の海面温度が1.5〜3°C上昇と一致した.
結論:
- 気候に起因する地表の生産性の低下,堆積物への有機物質供給の減少は,ベンシック酸素レベルに大きな影響を与えます.
- 表面の生産性の変化は,海洋循環パターンよりも,ベンシック酸素の調節においてより大きな役割を果たすかもしれない.
- 最近の気候変動は,特定の太平洋盆地堆積物における溶けた酸素の増加につながった.
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