Anaerobic nitrogen cycling on a Neoarchaean ocean margin
Anaerobic nitrogen cycling on a Neoarchaean ocean margin
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新太古代海洋边缘的厌氧氮循环
DOI：
10.1016/j.epsl.2019.115800
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发表时间：
2019
影响因子：
5.3
通讯作者：
Mettam C
中科院分区：
文献类型：
--
作者：
Mettam C
一个持续的好氧海洋氮循环的特点是生物介导的氧化铵硝酸盐可能已经到位，因为大氧化事件（GOE）约23亿年前。虽然从一些新太古代沉积物的氮同位素数据表明，短暂的硝酸盐的GOE之前的可用性，这些数据是开放的其他解释。尤其是这些数据来自相对深水的环境，这些环境在空间上与浅水环境分离，浅水环境是氧气积累和硝酸盐生成的最可能场所。在这里，我们提出了第一个氮同位素数据，从同期浅水沉积物，以限制氮循环浅晚古生代设置。BH-1 Sacha岩心穿过Campbellrand-Malmani碳酸盐台地，记录了从浅硅质岩/碳酸盐岩斜坡到边缘碳酸盐岩陆架的过渡，该过渡具有减少与开阔洋交流的潜力。在这些环境中，潮下至潮围和泻湖环境的氮同位素（δ 15 N）数据接近0‰，表明重氮营养或完全利用同位素组成接近0‰的重金属化铵。我们的数据集还包括负δ 15 N值，这表明存在浓度足以允许非定量同化的铵池。我们认为，这种情况可能是由于上涌的富磷深沃茨的透光带，刺激初级生产力，并创造了一个增强的有机物质，随后被eresalised和持续的主要缺氧的新太古代海洋环境的流量。值得注意的是，我们发现只有有限的证据耦合硝化/反硝化，即使在这些浅水环境中，质疑以前的建议，晚白垩世氮循环的特点是广泛的好氧氮循环。相反，有氧氮循环可能是空间异质性和绑定到高氧生产的位点，而浅水缺氧区持续存在。
A persistently aerobic marine nitrogen cycle featuring the biologically mediated oxidation of ammonium to nitrate has likely been in place since the Great Oxidation Event (GOE) some 2.3 billion years ago. Although nitrogen isotope data from some Neoarchaean sediments suggests transient nitrate availability prior to the GOE, these data are open to other interpretations. This is especially so as these data come from relatively deep-water environments that were spatially divorced from shallow-water settings that were the most likely sites for the accumulation of oxygen and the generation of nitrate. Here we present the first nitrogen isotope data from contemporaneous shallow-water sediments to constrain the nitrogen cycle in shallow Late Archaean settings. The BH-1 Sacha core through the Campbellrand-Malmani carbonate platform records a transition from a shallow siliciclastic/carbonate ramp to a rimmed carbonate shelf with the potential for reduced communication with the open ocean. In these settings nitrogen isotope (δ 15 N) data from sub-to peri-tidal and lagoonal settings are close to 0‰, indicating diazotrophy or the complete utilization of remineralised ammonium with an isotopic composition of near 0‰. Our dataset also includes negative δ 15 N values that suggest the presence of an ammonium pool of concentrations sufficient to have allowed for non-quantitative assimilation. We suggest that this condition may have been the result of upwelling of phosphorus-rich deep waters into the photic zone, stimulating primary productivity and creating an enhanced flux of organic matter that was subsequently remineralised and persisted in the dominantly anoxic Neoarchaean marine environment. Notably, we find only limited evidence of coupled nitrification/denitrification, even in these shallow water environments, calling into question previous suggestions that the Late Archaean nitrogen cycle was characterized by widespread aerobic nitrogen cycling. Rather, aerobic nitrogen cycling was likely spatially heterogeneous and tied to loci of high oxygen production while zones of shallow water anoxia persisted.
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DOI：
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发表时间：
2017
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作者：
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DOI：
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发表时间：
1995
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作者：
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DOI：
10.1073/pnas.1310488110
发表时间：
2013-11-19
影响因子：
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DOI：
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发表时间：
2009
期刊：
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