北大西洋への老化した陸上の有機物質の河川による輸出
1School of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, USA. praymond@mbl.edu
Nature
|February 24, 2001
まとめ
川は陸上の有機炭素を海洋に大量に排出する. 逆説的に,この炭素は大量の検出はされない. 研究によると,この炭素の大部分は海に到達する前に分解され,その構成が変化します.
科学分野:
- 地質化学 地質化学
- 海洋学 海洋学 海洋学
- 環境科学 環境科学
背景:
- 地球上の河川は,陸上の溶解した炭素と微粒子の有機炭素を海洋に輸送する.
- このインプットは,海洋の溶けた有機炭素の周回量を説明するのに理論的には十分である.
- しかし,陸上の有機物質は,河川の投入量に匹敵する量の海には見当たらない.
研究 の 目的:
- 河川によって北大西洋西部に排出される陸上の有機炭素の年代と組成を調べる.
- 陸上の有機物質が川から海へと運ばれる過程で,その運命を決定する.
- 河川の有機炭素投入と海洋の有機炭素貯蔵庫の間の不一致を調和させる.
主な方法:
- 自然放射性炭素 (14C) と安定炭素同位体 (13C) の河川溶解物や微粒子の有機物質の分析.
- 西北大西洋に流れる4つの川のサンプリング.
- 河川や沿岸の環境における有機物質の分解過程の評価.
主要な成果:
- 川は,地上の溶けた有機炭素 (14C濃縮) を,古い (14C濃縮) と若い (14C濃縮) の両方を輸出する.
- 川によって輸出される陸上の微粒子有機炭素は,主に古いものです.
- 若い溶解した有機炭素は,河川と沿岸の水中で選択的に分解され,より耐火性の成分を残します.
- これらの発見は,新たに生産された陸上の有機物質が河川の輸出を支配しているという以前の示唆に矛盾しています.
結論:
- 河川の有機物質は,輸出前の有意な老化と退化を経験しています.
- 選択的降解は,海洋への到達前に,陸上の有機物質の構造,分布,および量を変化させます.
- これらのプロセスは,海洋沈殿物と海水における陸上の有機物質の検出が低いことを説明するのに役立ちます.
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