熱帯植物のメチル塩化物の強い排出は,熱帯植物から発生する
Yoko Yokouchi1, Masumi Ikeda, Yoko Inuzuka
1National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. yokouchi@nies.go.jp
Nature
|March 15, 2002
まとめ
フェルンやDipterocarpaceaeのような熱帯植物は,オゾン層を破壊する化合物であるメチル塩化物の重要な天然源である. これらの発見は,以前は計算されていない排出量を説明するのに役立ち,大気中の塩素予算に影響を与えます.
科学分野:
- 大気化学 大気化学
- バイオジオケミストリー バイオジオケミストリー
- 環境科学 環境科学
背景:
- メチル塩化物は,大気中の塩素含有量に大きく寄与するオゾン層を破壊する塩素の主要な天然源です.
- 工業化以前の大気中の塩素濃度は,クロロフルオロ炭素のような人為的な源がないため,おそらく高かった.
- 既存のモデルは,未確認の排出源を示す,世界のメチル塩化物予算の不足を示している.
研究 の 目的:
- メチル塩化物排出量のこれまで未知の天然源を特定し,定量化する.
- メチル塩化物生産における特定の熱帯植物の役割を調査する.
- 世界的なメチル塩化物予算とその大気中の塩素への影響に関する理解を深めること.
主な方法:
- フェルンやDipterocarpaceaeを含む一般的な熱帯植物のメチル塩化物排出量のフィールド観測.
- 乾いた葉の質量単位/時間あたりの排出量の定量化.
- 東南アジアなどの特定の地域からのメチル塩化物流量の推定.
主要な成果:
- メチルクロライドの有意な排出は,特定の熱帯植物から観察され,乾燥した葉1時間あたり0.1~3.7μg/gの割合で観測されました.
- 東南アジアのDipterocarpaceaeからのメチル塩化物流は,年間0.91Tgと推定されています.
- これらの植物からの排出は,現在の大気予算で欠けているメチル塩化物源の相当な部分を占めています.
結論:
- 熱帯植物,特にフェルンやDipterocarpaceaeは,大気中のメチル塩化物の重要な寄与者です.
- これらの発見は,世界のメチル塩化物予算の不一致を解決するのに役立ちます.
- 熱帯森林伐採の将来の変化は,天然の塩素化合物源を変化させることができ,過去のフェルンの豊富さは,古代の大気に影響を及ぼした可能性があります.
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