Figure data and analysis for: The effect of grain size on porewater radiolysis

The radiolysis of porewaters by uranium, thorium, and potassium in mineral grains is a recognised source of molecular hydrogen in rock- and sediment-hosted fluids. This radiolytic hydrogen is of geomicrobiological interest as a potential energy source (electron donor) for microbial metabolism, especially in energy-limited settings such as the marine deep biosphere or the subsurface of Mars. Previous efforts to predict the production of radiolytic hydrogen from columns of rock and sediment have tended to rely upon analytic models that cannot account for the attenuation of mineral radiation by grains larger than ~30 microns. To address this, we have developed a Monte Carlo method to simulate the physics of mineral radiation and evaluate the production of H2 as a function of mineral grain size and radioisotope composition. The results confirm that grain size is a major control on radiolytic H2 yield. For example, using the standard geological classification of grain sizes, we find that cla...矿物颗粒中的铀、钍与钾对孔隙水的辐射分解，是赋存于岩石与沉积物流体中分子氢的公认来源。这类辐射分解产生的氢气具有地质微生物学研究价值，可作为微生物代谢的潜在能源（电子供体），尤其在海洋深部生物圈或火星地下等能量受限环境中具备重要研究意义。此前针对岩柱与沉积物柱的辐射分解氢产量预测研究，多依赖无法解释粒径大于约30微米颗粒对矿物辐射衰减效应的解析模型。为解决这一局限，本研究开发了蒙特卡洛（Monte Carlo）方法，用以模拟矿物辐射的物理过程，并基于矿物粒径与放射性同位素组成评估氢气产量。研究结果证实，粒径是辐射分解氢气产率的主要控制因素。例如，依据标准地质粒径分类方案，我们发现……