炭素の循環 炭素の循環 炭素の循環 太陽光は水柱を制御し,北極の淡水で炭素を処理する
Rose M Cory1, Collin P Ward2, Byron C Crump3
1Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109, USA. rmcory@umich.edu.
まとめ
永久凍土の解凍により,溶けた有機炭素 (DOC) が放出されます. 細菌の呼吸ではなく,光化学的酸化が,北極海域のDOC処理を主導し,世界の炭素予算に大きな影響を与えています.
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
- 気候科学 気候科学
背景:
- 永久凍土の解凍により,水系に大量に溶けた有機炭素 (DOC) が放出されます.
- このDOCの運命は,CO2に酸化されても,海洋に輸出されても,気候変動を理解する上で極めて重要です.
- 現在の理解では,主にDOCの処理は細菌の呼吸に起因している.
研究 の 目的:
- 永久凍土の影響を受けた北極海水の解凍における溶解有機炭素 (DOC) の運命を制御する主要なメカニズムを調査する.
- 光化学的酸化と細菌呼吸がDOC処理に与える相対的な貢献度を定量化するためです.
主な方法:
- 北極の湖や川のフィールドサンプリング.
- DOC処理速度を測定するためのインキュベーション実験.
- 光化学的および微生物的分解経路を区別する.
主要な成果:
- 光化学的酸化が,北極の湖や川におけるDOC除去の支配的なプロセスであることが判明しました.
- 光化学的酸化は,水柱で処理された全DOCの70~95%を占めました.
- DOCの光化学処理は,北極の地表水から排出される二酸化炭素の総量の相当な部分 (1/3) を占めています.
結論:
- 光化学的酸化は,北極の水環境における永久凍土の解凍によるDOCの処理において,細菌の呼吸よりも重要な役割を果たします.
- この発見は,北極圏の炭素予算における光分解の重要性と,世界の気候変動への影響を強調しています.
- これらの光化学的過程を気候モデルに完全に統合するには,さらなる研究が必要です.
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