二酸化炭素濃度が高い泥炭地帯から溶けた有機炭素を輸出する
C Freeman1, N Fenner, N J Ostle
1School of Biological Sciences, University of Wales, Bangor LL57 2UW, UK. c.freeman@bangor.ac.uk
Nature
|July 9, 2004
まとめ
泥炭地帯の河川における炭素の上昇は,温暖化や降雨の変化によるものではない. 代わりに,二酸化炭素濃度の上昇は植物の成長を刺激し,河川に溶けた有機炭素が増える.
科学分野:
- 環境科学 環境科学
- バイオジオケミストリー バイオジオケミストリー
- 気候変動科学 気候変動科学
背景:
- 泥炭地帯は,世界的な炭素を大量に貯蔵しています.
- 泥炭地帯を排水する河川の溶解有機炭素 (DOC) の上昇は,炭素貯蔵庫の不安定化の可能性を示唆しています.
- 温暖化と河川の排水に関する以前の仮説には説明力がない.
研究 の 目的:
- 溶けた有機炭素 (DOC) の濃度が,泥炭地帯を排水する河川で増加する要因を調査する.
- 降雨パターンの変化がDOCレベルに影響するという仮説を検証する.
- DOC濃度の上昇に起因する主なメカニズムを特定する.
主な方法:
- 温度,川の排水,降雨の季節性など,環境要因の分析.
- 主要生産性とDOCへの影響を評価するために,二酸化炭素濃度の実験操作.
- イソトープトレーシングは,DOCの源を決定する.
主要な成果:
- 温暖化と河川の排出量の増加は,DOCの上昇傾向を十分に説明できない.
- 降雨パターンの変化,特に夏の降雨は,観測されたDOC増加を説明できませんでした.
- 高濃度の二酸化炭素は,最近の一次生産から得られるDOCの割合を大幅に増加させた (対照群と比較して10倍増加).
結論:
- 純一次生産性の二酸化炭素媒介の刺激は,泥炭地帯の河川におけるDOCの増加の要因である可能性が高い.
- トートランドDOC濃度は,分解のみに影響する要因よりも,一次生産性に影響する要因に対してより敏感です.
- これらのメカニズムの理解は,気候変動下で泥炭地帯の炭素貯蔵庫の将来の安定性を予測するために不可欠です.
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