Certain subterranean environments of Earth have naturally accumulated long-lived radionuclides, such as ²³⁸U, ²³²Th, and ⁴⁰K, near the presence of liquid water. In these natural radioactive environments, water radiolysis can produce chemical species of biological importance, such as H₂. Although the proposal of radioactive decay as an alternative source of energy for living systems has existed for >30 years, this hypothesis gained strength after the recent discovery of a peculiar ecosystem in a gold mine in South Africa, whose existence is dependent on chemical species produced by water radiolysis. In this study, we calculate the chemical disequilibrium generated locally by water radiolysis due to gamma radiation. We then analyze the possible contribution of this disequilibrium for the emergence of life, considering conditions of early Earth and having as reference the alkaline hydrothermal vent theory. Results from our kinetic model point out the similarities between the conditions caused by water radiolysis and those found on alkaline hydrothermal systems. Our model produces a steady increase of pH with time, which favors the formation of a natural electrochemical gradient and the precipitation of minerals with catalytic activity for protometabolism in this aqueous environment. We conclude by describing a possible free-energy conversion mechanism based on protometabolism, which could be a requisite for the emergence of life in Hadean Earth.

中文翻译：

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自然放射性环境作为生命出现的局部不平衡源。

地球的某些地下环境在液态水附近自然积累了长寿命的放射性核素，例如²³⁸ U、²³² Th 和⁴⁰ K。在这些天然放射性环境中，水的辐射分解可以产生具有生物学重要性的化学物质，例如 H ₂. 尽管放射性衰变作为生命系统替代能源的提议已经存在超过 30 年，但在最近在南非的金矿中发现一个特殊的生态系统后，这一假设得到了支持，该生态系统的存在依赖于产生的化学物种通过水辐射分解。在这项研究中，我们计算了由伽马辐射引起的水辐射分解局部产生的化学不平衡。然后，我们考虑早期地球的条件并参考碱性热液喷口理论，分析这种不平衡对生命出现的可能贡献。我们的动力学模型的结果指出了由水辐射分解引起的条件与碱性热液系统中发现的条件之间的相似性。我们的模型会随着时间的推移稳定增加 pH，这有利于自然电化学梯度的形成和在这种水环境中具有催化活性的矿物质的沉淀。我们最后描述了一种基于原代谢的可能的自由能转换机制，这可能是冥界地球生命出现的必要条件。