北太平洋の亜熱帯渦巻の深層から地表近くの水域への窒素供給
Kenneth S Johnson1, Stephen C Riser, David M Karl
1Monterey Bay Aquarium Research Institute, Moss Landing, California 95039, USA. johnson@mbari.org
Nature
|June 26, 2010
まとめ
海洋の光合成は溶けた無機炭素 (DIC) を消費しますが,表面栄養素が不足しています. この研究では,深海の窒素欠乏が,エピソード的な栄養素輸送イベントによって支えられた,表面のDIC吸収のバランスをとることを明らかにしています.
科学分野:
- マリン・バイオジオケミストリー
- 海洋学 海洋学とは
- 化学海洋学 化学海洋学
背景:
- オリゴトロフィックな海洋表面水は,溶けた無機炭素 (DIC) の季節的な減少を示し,重要な光合成吸収を示しています.
- 栄養素の制限,特に窒素とリン酸の制限は,これらの地表水の重要な特徴です.
- 既存の栄養素供給メカニズムは,観察されたDIC吸収率をサポートするのに不十分と考えられています.
研究 の 目的:
- 栄養素に乏しい海洋表面層における生物学的DICの吸収をサポートするメカニズムを調査する.
- 北太平洋亜熱帯圏における栄養素の供給と需要のバランスを定量化するために.
- 主要生産の維持におけるエピソード性栄養素輸送の役割を評価する.
主な方法:
- プロファイリングフロートを使用して21ヶ月間にわたる窒素 (NO3−−−−−) と酸素 (O2−−2) の濃度の高解像度測定.
- 北太平洋亜熱帯回転圏のハワイ洋タイムシリーズステーション付近に展開.
- 季節のサイクルと水柱ステキオメトリーの分析.
主要な成果:
- 季節的なDIC消費とO(2) 生産は,100~250mの深さで溶解した窒素酸塩の不足と相関していた.
- 深海の窒素欠乏は,深海に輸出された窒素によってステキオメトリック的にバランスをとった.
- 短命 (10日未満) の栄養素輸送イベントが観察され,深層の窒素を地表水と結びつけました.
結論:
- 全体的な水柱 (0-250 m) は,栄養素の供給と需要のほぼ同値を示し,DICの吸収と表面上の栄養素の不足を調和させています.
- エピソード的栄養素輸送イベントは,オリゴトロフ地域における光合成のための栄養素の供給において重要な役割を果たします.
- これらの栄養素のダイナミクスを理解することは,地球規模の海洋におけるコミュニティの純生産の正確な評価に不可欠です.
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