Abstract The cycles of phosphorus, carbon and oxygen are intimately linked. Indeed, in many models, phosphorus is considered the driver of the carbon and oxygen cycles, and low concentrations of atmospheric oxygen during the Mesoproterozoic Era have been linked to extreme phosphorus limitation in the Mesoproterozoic oceans. To evaluate the Mesoproterozoic Era phosphorus cycle, we analyze the concentrations of phosphorus, organic carbon, and selected trace metals in several geological formations of Mesoproterozoic age. We combine these analyses with literature data to explore the relationship between phosphorus and organic carbon removal into Mesoproterozoic-Era sediments through a variety of water depths and water-column chemistries. We find that the ratio of organic carbon to reactive phosphorus (Corg/Preact) is largely invariant between different paleo-settings with average Corg/Preact that is either equal to or less than the Redfield ratio of 106/1 through all environments we explored. We put these results in the context of the modern phosphorus cycle which is reviewed here. Compared to modern phosphorus dynamics, we see no evidence for an anoxic-euxinic feedback between phosphorus burial, carbon burial and oxygen production during Mesoproterozoic Times. However, we do identify an additional potential phosphorus feedback related to the relationship between anoxia and deep-sea phosphorus dynamics that could have importance and oxygen regulation through time. We find the average value of Corg/Preact during the Mesoproterozoic Era is greater than the average for modern sediments. This result suggests that equal or more organic carbon was buried per unit of phosphorus during Mesoproterozoic times compared to today, a conclusion broadly consistent with the carbon isotope record. These results offer the possibility of a strong oxygen source to the atmosphere during the Mesoproterozoic Era, raising the conundrum as to why atmospheric oxygen levels were lower then, when compared to now. We suggest that a variety of factors may explain these differences in oxygen concentration including elevated rates of mantle degassing, reduced rates of phosphorus weathering and the lack of a terrestrial biosphere.

中文翻译：

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现代磷循环为中元古代磷动力学解释提供信息

摘要 磷、碳和氧的循环密切相关。事实上，在许多模型中，磷被认为是碳和氧循环的驱动因素，中元古代时期大气中低浓度的氧气与中元古代海洋中磷的极端限制有关。为了评估中元古代磷循环，我们分析了中元古代几个地质地层中磷、有机碳和选定的微量金属的浓度。我们将这些分析与文献数据相结合，通过各种水深和水柱化学性质探索磷和有机碳去除到中元古代沉积物中的关系。我们发现有机碳与活性磷的比率（Corg/Preact）在不同古环境之间很大程度上保持不变，在我们探索的所有环境中，平均 Corg/Preact 等于或小于 106/1 的 Redfield 比率。我们将这些结果置于此处回顾的现代磷循环的背景下。与现代磷动力学相比，我们没有看到中元古代时期磷埋藏、碳埋藏和氧气产生之间存在缺氧-富氧反馈的证据。然而，我们确实确定了一个额外的潜在磷反馈，与缺氧和深海磷动力学之间的关系有关，这可能具有重要性，并且随着时间的推移氧气调节。我们发现中元古代时期 Corg/Preact 的平均值大于现代沉积物的平均值。这一结果表明，与今天相比，中元古代时期每单位磷埋藏了相等或更多的有机碳，这一结论与碳同位素记录大体一致。这些结果提供了在中元古代为大气提供强氧源的可能性，从而引发了一个难题，即为什么当时与现在相比大气氧含量较低。我们认为，多种因素可以解释氧浓度的这些差异，包括地幔脱气速率升高、磷风化速率降低以及缺乏陆地生物圈。这一结果表明，与今天相比，中元古代时期每单位磷埋藏了相等或更多的有机碳，这一结论与碳同位素记录大体一致。这些结果提供了在中元古代为大气提供强氧源的可能性，从而引发了一个难题，即为什么与现在相比，当时大气中的氧含量较低。我们认为，多种因素可以解释氧浓度的这些差异，包括地幔脱气速率升高、磷风化速率降低以及缺乏陆地生物圈。这一结果表明，与今天相比，中元古代时期每单位磷埋藏了相等或更多的有机碳，这一结论与碳同位素记录大体一致。这些结果提供了在中元古代为大气提供强氧源的可能性，从而引发了一个难题，即为什么与现在相比，当时大气中的氧含量较低。我们认为，多种因素可以解释氧浓度的这些差异，包括地幔脱气速率升高、磷风化速率降低以及缺乏陆地生物圈。提出了一个难题，即为什么当时的大气氧含量比现在低。我们认为，多种因素可以解释氧浓度的这些差异，包括地幔脱气速率升高、磷风化速率降低以及缺乏陆地生物圈。提出了一个难题，即为什么当时的大气氧含量比现在低。我们认为，多种因素可以解释氧浓度的这些差异，包括地幔脱气速率升高、磷风化速率降低以及缺乏陆地生物圈。