高四次期の大気中のCH4イソトープ記録は,海洋クラスラートが安定していることを示唆しています
1Department of Geosciences and the Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, USA. sowers@geosc.psu.edu
まとめ
海洋クラスラートの不安定化は,最後の氷河周期中に大気中のメタンの急激な増加を引き起こさなかった. 代わりに,メタンのデウテリウム/水素同位体比の増加は,湿地および石油排出量の変化を示唆しています.
科学分野:
- 古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは
- 地質化学 地質化学
- 大気科学 大気科学
背景:
- 最後の氷河期における大気中のメタン (CH4) の急激な増加は,クラスラートの不安定化の可能性と関連付けられています.
- 海洋クラスラートには独特のデウテリウム/水素 (D/H) 同位体比があり,その不安定化により大気中のCH4のD/H比 (deltaD(CH4) が変化する.
研究 の 目的:
- 最後の氷河期間の大気中のCH4の急激な増加における海洋クラトラート不安定化の役割を調査する.
- 主要な古気候現象の際にデルタD (((CH4) シグネチャーを分析する.
主な方法:
- 第2次グリーンランド氷床プロジェクトからの氷芯に閉じ込められた空気の分析.
- 大気中のメタンのデウテリウム/水素 (D/H) 同位体比 (deltaD(CH4) の測定.
主要な成果:
- 安定したおよび/または減少するデルタD ((CH4) 値は,若いドライアスの終わり,古いドライアス,および1つのスタジアル期間に観察されました.
- これらの発見は,これらの急激な温暖化エピソードの間,海洋クラトラットが安定したままでしたことを示しています.
結論:
- 海洋クラスラートの不安定化は,研究された氷河期間に観測された大気中の突然のCH4増加の原因ではありませんでした.
- 氷河デルタD ((CH4) 値の上昇は,湿地のCH4排出量の純と総排出量の比率の低下と石油ベースの排出量の増加に起因する可能性があります.
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