在前坎布里亚时期,铁和氧气生物地化学循环的演变
Yasuto Watanabe1, Eiichi Tajika1, Kazumi Ozaki2,3,4
1Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
Geobiology
|August 25, 2023
概括
大氧化事件 (GOE) 在地球的铁和氧气循环中引发了重大变化. 我们的模型揭示了氧气水平上升如何将铁沉积物从地表水中转移到深海.
科学领域:
- 地质化学 地质化学
- 生物地质化学生物地质化学
- 古海洋学是古海洋学.
背景情况:
- 前坎布里亚时代的海洋经历了铁质 (富含铁) 的条件,但铁和氧气循环在大氧化事件 (GOE) 的演变仍然不清楚.
- 地质记录显示,铁质水在GOE之前和之后持续存在,这表明生命和地球环境之间的复杂相互作用.
研究的目的:
- 通过使用生物地球化学模型,研究铁,氧,和碳循环在GOE的合生物地球化学进化.
- 了解海洋铁循环对氧气生产速度和氧化途径变化的敏感性.
主要方法:
- 开发一个模拟Fe-O2-P-C循环的生物地球化学模型.
- 对模型输出的分析,以评估氧气水平对铁的物种化和沉积的影响.
- 调查铁氧化路径和沉积点转移的门.
主要成果:
- 在GOE之前,海洋铁循环对氧气变化不敏感 (pO2 < 10^-6 PAL).
- 由供应引发的能源政府将大气pO2提高到10^-3 - 10^-1 PAL.
- 在GOE后,海洋铁度对pO2变得高度敏感,可能导致氧化还原波动.
- 一个pO2值 (~0.3%PAL) 转移了Fe(II) 氧化从无氧的光自营养物到非生物过程,将Fe(III) 沉积转移到深海.
结论:
- 该模型通过详细介绍铁沉积机制的转变来解释前坎布里亚铁形成的停止.
- 原生态海洋氧化还原条件可能波动,影响全球生物地质化学循环.
- 这项研究为从表面沉积到深海沉积铁的过渡提供了机制性的解释.
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