近日，瑞士苏黎世联邦理工学院Nir Galili团队研究了海洋从氧化铁中溶解有机碳的地质历史。该研究于2025年8月13日发表在《自然》杂志上。

溶解有机碳（DOC）是现代海洋中最大的还原碳库。其动态调节海洋群落和大气CO₂水平，而¹³C组成跟踪生态系统结构和自养代谢。然而，海洋DOC的地质历史在很大程度上仍然是不受约束的，这限制了它们机械地重建生态和生物地球化学耦合演化的能力。

研究组开发并验证了过去DOC签名的直接代理，这些签名主题是铁类中共沉淀有机碳。他们将其应用于过去16.5亿年沉积的26个海洋含铁地层，以生成古元古代以来海洋DOC信号的基于数据的重建。预测的DOC浓度在古元古代接近现代水平，然后在新元古代下降了90-99%，然后在寒武纪急剧上升。

研究组将这些动态解释为反映三种不同的状态。主要是小型单细胞生物的出现与严重缺氧的深海相结合，其次是更大、更复杂的生物，海洋氧合变化不大，最后是生物的持续生长和向完全氧合海洋的过渡。此外，现代DOC相对于元古代富集了¹³C，这可能是由于生物创新驱动的自养碳同位素分馏的变化。该发现反映了碳循环、海洋氧合和复杂生命进化之间的联系。

附：英文原文

Title: The geologic history of marine dissolved organic carbon from iron oxides

Author: Galili, Nir, Bernasconi, Stefano M., Nissan, Alon, Alcolombri, Uria, Aquila, Giorgia, Di Bella, Marcella, Blattmann, Thomas M., Haghipour, Negar, Italiano, Francesco, Jaggi, Madalina, Kaplan-Ashiri, Ifat, Lee, Kang Soo, Lechte, Maxwell A., Magnabosco, Cara, Porter, Susannah M., Rudmin, Maxim, Spencer, Robert G. M., Stocker, Roman, Wang, Zhe, Wohlwend, Stephan, Hemingway, Jordon D.

Issue&Volume: 2025-08-13

Abstract: Dissolved organic carbon (DOC) is the largest reduced carbon reservoir in modern oceans1,2. Its dynamics regulate marine communities and atmospheric CO2 levels3,4, whereas 13C compositions track ecosystem structure and autotrophic metabolism5. However, the geologic history of marine DOC remains largely unconstrained6,7, limiting our ability to mechanistically reconstruct coupled ecological and biogeochemical evolution. Here we develop and validate a direct proxy for past DOC signatures using co-precipitated organic carbon in iron ooids. We apply this to 26 marine iron ooid-containing formations deposited over the past 1,650 million years to generate a data-based reconstruction of marine DOC signals since the Palaeoproterozoic. Our predicted DOC concentrations were near modern levels in the Palaeoproterozoic, then decreased by 9099% in the Neoproterozoic before sharply rising in the Cambrian. We interpret these dynamics to reflect three distinct states. The occurrence of mostly small, single-celled organisms combined with severely hypoxic deep oceans, followed by larger, more complex organisms and little change in ocean oxygenation and finally continued organism growth and a transition to fully oxygenated oceans8,9. Furthermore, modern DOC is 13C-enriched relative to the Proterozoic, possibly because of changing autotrophic carbon-isotope fractionation driven by biological innovation. Our findings reflect connections between the carbon cycle, ocean oxygenation and the evolution of complex life.

DOI: 10.1038/s41586-025-09383-3

Source: https://www.nature.com/articles/s41586-025-09383-3