近日，南京大学彭永波团队研究了地球表面20亿年的过渡性氧化作用。该研究于2025年8月27日发表在《自然》杂志上。

地球表面在其历史晚期持续地达到现代水平之前经历了逐步的氧化，但这一转变的细节仍不清楚。

研究组展示了沉积硫酸盐（Δ'¹⁷O_sulfate）中与质量无关的氧同位素的高分辨率2.5 Gyr记录，这与O₂（pO₂）的大气分压有关。该记录与现有的沉积Δ³³S数据一起，证明了一个2-Gyr转变，其特征是在24亿年前（Ga）和0.41Ga后的现代pO₂状态在1.0Ga之后水平相对较高。他们的数据还显示，在新元古代主要的碳酸盐岩-δ¹³C负偏移过程中，Δ'¹⁷O_sulfate和sulfate-δ³⁴S的耦合下降。

定量生物地球化学模拟表明，这些同位素耦合反映了pO₂的增加，这可能通过增加的大气O₂流入驱动了间歇性的海洋氧合。这一过程加剧了海洋有机物的氧化和硫化物的减少，同时作为负反馈引发了暂时的pO₂下降。这些发现支持了一个动态的、漫长的大气和海洋共氧历史——以长期的正耦合和短期的负反馈为特征——为异常的新元古代碳循环和复杂生命的持续的、偶然的兴起提供了一个一致的解释。

附：英文原文

Title: Two-billion-year transitional oxygenation of the Earth’s surface

Author: Wang, Haiyang, Li, Chao, Peng, Yongbo, Zhang, Junpeng, Cheng, Meng, Cao, Xiaobin, Qie, Wenkun, Zhang, Zihu, Dodd, Matthew S., Hou, Mingcai, Wallace, Malcolm, v. S. Hood, Ashleigh, Lyons, Timothy W., Bao, Huiming

Issue&Volume: 2025-08-27

Abstract: Earth’s surface underwent stepwise oxygenation before persistently reaching modern levels late in its history1,2,3,4,5, but the details of this transition remain unclear5,6,7,8,9,10,11,12,13,14,15,16. Here we present a high-resolution 2.5-Gyr record of mass-independent oxygen isotopes in sedimentary sulfate (Δ′17Osulfate), a proxy linked to the atmospheric partial pressure of O2 (po2)17,18,19. This record, together with existing sedimentary Δ33S data20,21,22, demonstrates a 2-Gyr transition characterized by generally low, fluctuating po2 between an O2-free state before 2.4billion years ago (Ga) and a modern po2 state after 0.41Ga, with relatively elevated levels after 1.0Ga. Our data also show coupled declines in Δ′17Osulfate and sulfate-δ34S during major negative carbonate-δ13C excursions in the Neoproterozoic. Quantitative biogeochemical modelling indicates that these isotopic couplings reflect the increasing po2, which may have driven episodic ocean oxygenation through an increased atmospheric O2 influx. This process intensified the oxidation of marine organics and reduced-sulfur species, while triggering temporary po2 drawdowns as negative feedback15. These findings support a dynamic, lengthy co-oxygenation history for the atmosphere and oceans—marked by long-term positive coupling and short-term negative feedbacks—offering a coherent explanation for the anomalous Neoproterozoic carbon cycles23,24 and the protracted, episodic rise of complex life25,26,27.

DOI: 10.1038/s41586-025-09471-4

Source: https://www.nature.com/articles/s41586-025-09471-4