まとめ
世界的な酸化窒素 (N2O) 予算は不均衡である. 土壌からの排出量は同位体的に軽量であり,予算のバランスをとるために,重量のN2O源,潜在的に平流層または海洋から必要である.
科学分野:
- 地球システム科学 地球システム科学
- 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:
- 酸化窒素 (N2O) の世界の予算は,平流層の破壊と土壌と海洋からの推定生産の間の重要な不均衡を示しています.
- 熱帯雨林や肥沃土を含む熱帯圏のN2O源は,重い同位体 (15Nと18O) で枯渇したN2Oを放出します.
研究 の 目的:
- 主要な地上の源からのN2Oの同位体組成を調査する.
- グローバル予算のバランスをとるために必要な欠けているN2O源を特定する.
- 極地氷の核における同位体変動の影響を理解する.
主な方法:
- トロポスフィアのN2Oサンプルにおける15N/14Nおよび18O/16O比率の測定.
- 熱帯雨林の土壌 (コスタリカ) と肥えた農業用土壌 (マウイ) のN2Oの分析.
- 世界的なN2O予算のバランスをとるため,同位体フローのモデリング.
主要な成果:
- 熱帯雨林と肥えた畑の両方から土壌に由来するN2Oは,平均熱帯圏のN2Oと比較して15Nと18Oで大幅に枯渇しています.
- 土壌からの軽量のN2Oのバランスを取るために,15Nと18Oで濃縮された,同位体的に重いN2Oの大量の源が必要である.
- 光分解により重イソトープで濃縮された平流層のN2Oと,潜在的に大きな海洋流は,このバランスソースの候補である.
結論:
- 土壌のN2Oの同位体シグネチャーは,世界の予算に重大な不均衡があることを示唆しています.
- ストラトスフィアと海洋の流れは,重量イソトープ濃縮により,世界のN2O予算のバランスをとる上で重要な役割を果たしています.
- 北極の氷の核におけるN2Oの同位体変動は,過去のN2O予算の動態と気候の相互作用に関する洞察を提供します.
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