直接的な測定に基づく海洋二酸化窒素固定率の倍増
Tobias Großkopf1, Wiebke Mohr, Tina Baustian
1Helmholtz Centre for Ocean Research Kiel, Kiel, Germany. tgrosskopf@geomar.de
Nature
|August 11, 2012
まとめ
海洋の窒素固定は,海洋の生産性にとって極めて重要です. 新しい方法は,確立された技術が窒素固定率を過小評価することを明らかにし,特に多様な微生物が関与する場合は,これまで推定されていたよりも高いグローバルな割合を示唆しています.
科学分野:
- 海洋微生物生態学について
- バイオジオケミカルサイクルとは
- 海洋学 海洋学 海洋学
背景:
- 生物学的二酸化窒素固定は,海洋における窒素の主要な源であり,一次生産性を調節する.
- 現在の推定では,窒素の損失が固定量を上回り,海洋窒素予算に赤字が生じることを示唆しています.
- 海洋のN2固定を測定するための確立された方法は,ダイアゾトロフの完全な貢献を正確に捉えることができないかもしれません.
研究 の 目的:
- 海洋のN2固定率を測定するための新しく開発された方法と確立された方法を比較するために.
- ディアゾトロフコミュニティの構成がN2固定速度の測定にどのように影響するかを調査する.
- 盆地全体および世界の海洋N2固定率を再評価する.
主な方法:
- ダイアゾトロフクラドの豊富さを定量化するために分子技術を活用した.
- 有機粒子物質に15N2の組み込み率を測定した.
- 異なる海洋地域における既定および新しい方法から得られたN2固定率の比較.
主要な成果:
- 確立された方法は,N2固定率を過小評価しています,特にトリコデスミウムが支配する地域 (平均62%).
- 新しい方法は,単細胞サイアノバクテリアとg-プロテオバクテリアが優位であったとき,かなり高いN2固定率 (6倍以上) を得ました.
- 大西洋盆地全体のN2固定率は14 ± 1 Tg N yr−1 (確立) と24 ± 1 Tg N yr−1 (新しい方法) として計算されました.
結論:
- ダイアゾトロフィックコミュニティの構成は,測定されたN2固定率に大きく影響します.
- 既存の方法は,世界の海洋のN2固定を過小評価している可能性が高い.
- 世界的な海洋のN2固定率は,以前に推定されたものより大幅に高く,Trichodesmium以外のダイアゾトロフの貢献が大きい可能性があります.
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