まとめ
大気中のメタンのレベルは,過去300年間で急速に上昇し,倍増し,また倍増すると予測されています. 氷の核の分析により,バイオマスの燃焼がメタンの濃縮の主な原動力であることが明らかになった.
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
- 大気化学 大気化学
- イソトープ地球化学 イソトープ地球化学
背景:
- 北極の氷芯には空気の泡が閉じ込められ,歴史的な大気サンプルを提供している.
- メタン (CH4) は,気候に重要な役割を果たす強力な温室効果ガスです.
- 過去の大気中のメタンの濃度と同位体シグネチャーは,気候の動態を理解するために重要である.
研究 の 目的:
- 極地氷の核を用いて,過去の大気中のメタン濃度と同位体比を分析する.
- 大気中のメタンの最近の増加に起因する主要な原因を特定する.
- 氷核に保存されたメタン濃度と同位体データの完全性を検証するために.
主な方法:
- 北極の氷の核からの空気泡を分析して,過去のメタンの混合比率を決定する.
- 氷の核サンプルからメタンの炭素同位体比 (13C/12C) の測定.
- 4メートルの長い氷芯の断片と約25キログラムの氷を使用して,最大350年前のメタンの分析を行いました.
主要な成果:
- メタンの混合比率は,約300年前から急速に増加し始めた.
- 大気中のメタンの炭素13と炭素12の比率は,現在と比較して100~300年前の氷の1ミリあたり約2パーセント低かった.
- 氷の核内のin situプロセスは,メタンの濃度や同位体比を大幅に変化させていない.
結論:
- 人為的なバイオマス燃焼は,大気中のメタン (CH4) の最近の濃縮の主な原因として特定されています.
- この研究は,過去の大気中のメタン同位体組成を再構築するための氷核の信頼性を確認しています.
- バイオマスの燃焼が鍵となる一方で,メタンの濃縮に寄与する他の要因も存在する可能性があります.
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