Maratrat L, Jaziri A Y, Millan M, Moulay V, Vettier L, Govekar T, Abello A, Carrasco N
Université Paris-Saclay, UVSQ, CNRS, LATMOS, Guyancourt, 78280, France.
ENS-Paris-Saclay, Gif sur Yvette, 91190, France.
Sci Rep. 2025 Aug 11;15(1):29284. doi: 10.1038/s41598-025-13441-1.
The transition period of the Great Oxidation Event (GOE) saw the emergence of transient physical and chemical processes. In this context, photochemical organic hazes may have evolved in an atmosphere containing low concentrations of oxygen (< 10/10 Present Atmospheric Level). This coexistence of organic aerosols and oxygen traces induced an atmospheric reactivity which has so far been unexplored. Here, we show that the progressive rise of oxygen around the GOE triggered oxidation of organic aerosols suspected to be present at that time. We estimate that such transient mechanisms would have persisted over 60 to 100 Myrs during the GOE and possibly extended during the Archean. The main chemical markers of aerosol oxidation observed are urea, oxalic acid and carboxylic acid derivatives. These oxygen-bearing organics identified could have served as nutrients by existing ecosystems. This input of oxidized organic matter, estimated between 10 and 10 g of C.yr based on aerosol production yields, has probably been significant compared to oxygenic photosynthesis. Such mechanisms could also have diversified the pool of available nutrients, constituting an interesting vector of biodiversity for the primitive ecosystem.
大氧化事件（GOE）的过渡时期出现了短暂的物理和化学过程。在这种情况下，光化学有机霾可能在低氧浓度（<10/10现代大气水平）的大气中演化。有机气溶胶与微量氧气的这种共存引发了一种迄今为止尚未被探索的大气反应性。在这里，我们表明，大氧化事件期间氧气的逐渐增加引发了当时疑似存在的有机气溶胶的氧化。我们估计，这种瞬态机制在大氧化事件期间会持续60至100百万年，并可能在太古代期间进一步扩展。观察到的气溶胶氧化的主要化学标志物是尿素、草酸和羧酸衍生物。这些已识别的含氧有机物可能已被当时存在的生态系统用作养分。根据气溶胶产生率估算，这种氧化有机物质的输入量在每年10至10克碳之间，与氧光合作用相比可能相当可观。这种机制还可能使可用养分库多样化，构成原始生态系统中生物多样性的一个有趣载体。
