终端原生生态生物地化学循环的重组
G A Logan1, J M Hayes, G B Hieshima
1Departments of Geological Sciences and of Chemistry, Indiana University, Bloomington 47405-1403, USA.
Nature
|July 6, 1995
概括
原生态的碳化合物显示,细菌而不是藻类主导了早期的海洋食物网. 这种细菌的重新处理限制了海洋的氧化,延迟了坎布里亚爆炸,直到有机物质的高效沉没进化.
科学领域:
- 地质化学 地质化学
- 古生物学的古生物学
- 海洋生物学 海洋生物学
背景情况:
- 原生态时代 (2.5亿到5.4亿年前) 标志着氧气水平的上升,多细胞生命和动物的坎布里亚辐射.
- 连接这些深刻的生物和环境转变的机制仍然不太清楚.
研究的目的:
- 调查前世沉积物中碳化合物的来源,以了解早期海洋生态系统的功能.
- 为了阐明微生物过程在调节海洋氧化过程中的作用,在Proterozoic.
主要方法:
- 从全球原生代沉积物样本中提取的碳化合物生物标志物的分析.
- 解释生物标志物的起源,以区分光合作用和异质输入.
- 模拟微生物活动对有机物降解和海洋化学的影响.
主要成果:
- 原生态碳化合物主要来自细菌和异质生物,而不是光合作用生物.
- 有机物在水柱中发生了广泛的生物降解,通过减少硫酸盐的细菌进行中介.
- 这一过程产生了硫化物,消耗了氧气,并限制了其向深海运输.
- 在坎布里亚早期改善了藻类脂质的保存,与通过便颗粒的沉没率增加有关.
结论:
- 有机物质的不完全降解和缓慢沉没在前生代有限的海洋氧化.
- 坎布里亚时代通过便颗粒有效地出口有机物质的演变增加了地表水的氧化.
- 这种转变促进了氧硫化物界面的下降,从根本上改变了海洋环境,并导致了坎布里亚辐射.
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