沿岸の塩沼から排出される天然メチルブロミドおよびメチル塩化物の排出量
R C Rhew1, B R Miller, R F Weiss
1Scripps Institution of Oceanography, University of California at San Diego, La Jolla 92093-0244, USA. rob@gaslab.ucsd.edu
Nature
|February 5, 2000
まとめ
沿岸の塩沼は,大気中のメチルブロミド (CH3Br) とメチル塩化物 (CH3Cl) の重要な天然源であり,オゾン層の健康に極めて重要です. これらの生態系は,表面積が小さいにもかかわらず,世界の排出量の10%を占める可能性があります.
科学分野:
- 大気化学 大気化学
- 環境科学 環境科学
- エコロジー エコロジー エコロジー
背景:
- 大気中のメチルブロミド (CH3Br) とメチル塩化物 (CH3Cl) は,平流層のオゾン層の減少に関与している.
- 現在のCH3BrとCH3Clの排出量の推定値は,既知の損失プロセスと一致せず,潜在的な自然資源が欠けていることを示しています.
- 陸上の生態系は,これらの化合物の世界的な予算においてより重要な役割を果たしていると考えられています.
研究 の 目的:
- 大気中のメチルブロミド (CH3Br) とメチル塩化物 (CH3Cl) の源泉としての沿岸塩沼の役割を調査する.
- 塩沼内の異なる植生地帯からのCH3BrとCH3Clの流れを定量化するために.
- 大気中のCH3BrとCH3Cl予算に対する塩沼の世界的な重要性を評価する.
主な方法:
- CH3BrとCH3Clの流れのフィールド測定は,2つの沿岸の塩沼生態系で行われました.
- 空間的変動を捉えるために,様々な植生地帯の流れを測定した.
- 排出量の昼間と季節の変動をモニターした.
主要な成果:
- CH3BrとCH3Clの大量の流れが,沿岸の塩沼地における,研究されたすべての植生地帯から検出されました.
- 測定した流量は,CH3Brで最大42ミクロモールm(-2) d(-1),CH3Clで最大570ミクロモールm(-2) d(-1) に達した.
- CH3BrとCH3Clの流れの間の強い正の相関が観察され,モラ比率は約1:20であった.
- 排出量は,相当な昼間,季節,空間的な変動を示した.
結論:
- 沿岸の塩沼は,大気中のCH3BrとCH3Clの実質的な,以前に過小評価された天然源を表しています.
- これらの生態系は,小さな地球面積 (<0.1%) をカバーしているにもかかわらず,世界のCH3BrおよびCH3Cl排出量に約10%の貢献をすることができる.
- この発見は,オゾン層の減少に関する研究のための地球大気モデルに塩沼の排出量を含めることの重要性を強調しています.
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