米畑からのメチルハリドとメタンの排出量
1Department of Earth System Science, Department of Chemistry, University of California, Irvine, CA 92697, USA.
まとめ
米栽培は大気中のメチルハリド濃度に大きな影響を及ぼします. 浸水した米畑は,大気中のメチルブロミドとメチルヨウ酸化物の排出に貢献し,耕作されていない畑は大量にメチル塩化物を排出します.
科学分野:
- 大気化学 大気化学
- 環境科学 環境科学
- 農業科学 農業科学とは
背景:
- メチルハリドガス (メチル塩化物,メチルブロミド,メチルヨウ酸化物) は,大気中の重要な無機ハロゲン化合物である.
- これらの化合物は,平流圏と熱帯圏の化学プロセスにおいて重要な役割を果たします.
- これらのガスの発生源を理解することは,大気モデリングと気候研究に不可欠です.
研究 の 目的:
- カリフォルニアの水浸された米畑からのメチルハライドの排出量を定量化するために.
- 米栽培のメチル塩化物,メチルブロミド,メチルヨーデドの大気予算への貢献を評価する.
- これらの排出に影響を与える要因を特定する.
主な方法:
- カリフォルニアの水没した米畑からのメチルハライドガス排出量の観測.
- 米の成長段階,土壌の有機成分,ハライド濃度,水管理などの要因の分析.
- フィールドデータを抽出して,世界の農業貢献を推定する.
主要な成果:
- 米畑は,大気中のメチルブロミドとメチルヨウ酸化物の顕著な源です.
- 大気中のメチルブロミドの約1%とメチルヨウ酸化物の5%は,世界の米畑から発生しています.
- 植え付けされていない浸水した米畑は,植え付けされた畑と同等の割合でメチル塩化物を排出します.
結論:
- 米の農業は,大気中のメチルハリドの重要で量化可能な源である.
- フィールド管理と成長段階は,メチルハリド排出量の決定的な決定因子です.
- 大気中のハロゲンサイクルに対する農業の影響に関するさらなる研究が必要である.
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