氧同位素分离O2消费通过无生物光化学单片氧气形成途径
Sarah G Pati1,2, Lara M Brunner2, Martin Ley2
1Department of Environmental Geosciences, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna 1090, Austria.
ACS environmental Au
|March 24, 2025
概括
之前被忽视的光化学氧气损失显著影响水生环境中的氧气同位素比率. 这项研究量化了这种效应,揭示了它对了解氧气循环的重要性.
科学领域:
- 生物地质化学生物地质化学
- 环境化学环境化学
- 稳定同位素地球化学 稳定同位素地球化学
背景情况:
- 在O2中,氧同位素比率 (18O/16O,17O/16O) 是水生生地化学过程的关键标记物.
- 使用这些同位素比率来量化生物O2生产和呼吸.
- 在以同位素为基础的氧气循环评估中,阳光照射水中的光化学O2消耗被忽视了.
研究的目的:
- 在非生物光化学O2消除过程中量化氧同位素分离.
- 研究单片氧 (O2) 在这些光化学过程中的作用.
- 评估对评估水生系统中氧气循环的影响.
主要方法:
- 实验性确定O同位素分离的光化学O2损失使用孟加拉作为O2敏感剂.
- 用各种有机灭剂 (氨基酸,醇) 进行光依赖O2去除的动态分析.
- 应用一个前平衡模型来合理化观察到的O同位素分离和明显的O动态同位素效应 (O-AKIEs).
主要成果:
- 通过O2形成的光化学O2消除会导致显著的O同位素分离.
- 对氧化反应的明显O-AKIE被确定为大约1.03.
- 随着O2氧化与衰变速率的比率的增加,O同位素分离接近统一.
- 同位素丰富系数 (18O-ε) 达到高达-30‰,相当于生物呼吸效应.
结论:
- 在基于稳定同位素的水生氧循环评估中,必须考虑光化学O2消耗.
- 这种非生物过程可以显著影响O同位素的签名,模仿生物呼吸.
- 对生物地质化学O2循环的未来研究应该纳入光化学O2损失机制.
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