メチル塩化物の強い源は,熱帯の海岸地帯から大気中に排出される
Y Yokouchi1, Y Noijiri, L A Barrie
1National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan. yokouchi@nies.go.jp
Nature
|February 5, 2000
まとめ
メチル塩化物 (CH3Cl) は,大気中の有毒炭素である. 新しい研究は,暖かい海岸地帯,特に熱帯の島が主要な源であり,以前の海洋排出理論に挑戦していることを示しています.
科学分野:
- 大気化学 大気化学
- 環境科学 環境科学
- ハロカーボン研究 ハロカーボン研究
背景:
- メチル塩化物 (CH3Cl) は,大気中の最も豊富に存在するハロカーボンであり,平流圏の塩素の天然源である.
- 推定の世界的なCH3Clの流れは3.5Tgで,OHの急性反応による大気中の寿命は1.5年である.
- 以前は,海洋からの排出が主要な原因と考えられ,二次的な原因はバイオマスの燃焼であった.
研究 の 目的:
- 大気中のメチル塩化物 (CH3Cl) の源を調査するために,海洋の流れが不十分であるという最近の発見を考慮して.
- CH3Cl排出量の代替的な有意な源を特定する.
主な方法:
- 大気中のCH3Cl濃度に関する世界的なモニタリング研究を実施しました.
- 様々な場所でスポット測定を行いました.
- CH3Clと陸上の植物の生物学的化合物の相関を分析した.
- 試験されたCH3Cl濃度のOH関連季節性.
主要な成果:
- 最近の海水測定では,海洋流が世界のCH3Cl流のわずか12%を占めていることを示唆しています.
- 温暖な沿岸地域,特に熱帯の島々から発生するCH3Clの排出量が大幅に増加している.
- 熱帯では大気中のCH3Clの上昇が観測されています.
- CH3Cl濃度と陸上の植物生物学的化合物との間に強い相関が見出されました.
- 中高緯度でOH関連季節性が検出されました.
結論:
- 温暖な海岸地帯,特に熱帯諸島は,以前は過小評価されていた大気中のメチル塩化物の重要な源である.
- CH3Clの強い赤道的な源は,半球間の均一な分布を説明することができます.
- 世界的なCH3Cl源の再評価は必要であり,海洋とバイオマス燃焼の起源を超えて進む必要があります.
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