Early Life Record from Nitrogen Isotopes
Early Life Record from Nitrogen Isotopes
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DOI：
10.1007/978-90-481-8794-2_8
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
D. Pinti;K. Hashizume
中科院分区：
文献类型：
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作者：
D. Pinti;K. Hashizume
生物活动以一种特殊的方式分离氮同位素，使它们成为可靠的生物标志和准确的古环境指标。长期以来，氮一直被忽视，与更稳定的碳的石墨化形式相比，氮是极其脆弱的；然而，与碳和硫的其他同位素体系相比，氮具有优势。地球表面的主要氮来源，即大气中的三键氮，是如此稳定，以至于只有非常有限的代谢过程才能连接非生物和生物世界。因此，我们可以画出相对简单的N的通量模型。在这一贡献中，我们回顾了过去40亿年的N同位素记录。氮记录到的大的同位素位移与特定的代谢变化有关，作为对主要环境胁迫的直接反应，例如大气中氧气的增加和海洋中硝化细菌和反硝化细菌的进化。这些同位素变化不是唯一的，但与C和Fe的变化有很好的相关性，表明氮可以成功地用于模拟地球历史上不断变化的微生物新陈代谢的相互作用，并将它们与精确的环境变化联系起来。
Biological activity fractionates the nitrogen isotopes in a peculiar way, making them a reliable biosignature and an accurate paleoenvironmental proxy. Nitrogen has been ignored for long time, being extremely fragile compared to the more stable graphitic forms of C; however, N has an advantage over other isotopic systems such as those of C and S. The dominant source of N at the surface of the Earth, that is, the atmospheric triple-bonded N2, is so stable that only a very limited number of metabolic processes can bridge the abiotic and biotic world. Therefore we can draw relatively simple flux models for N. In this contribution, we review the N isotopic record in the last 4 billions years. Large isotopic shifts recorded by nitrogen are related to specific metabolic changes as a direct response to major environmental stress such as the rise of oxygen in the atmosphere and the evolution of nitrifiers and denitrifiers in the ocean. These isotopic changes are not unique but well correlated with those of C and Fe, indicating that nitrogen can be successfully used for modeling the interplay of changing microbial metabolisms over Earth’s history and relate them to precise environmental changes.