van der Graaf Charlotte M, Sánchez-España Javier, Ilin Andrey M, Yusta Iñaki, Stams Alfons J M, Sánchez-Andrea Irene
Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
Faculty of Civil Engineering and Geoscience, Department of Geoscience and Engineering, Delft University of Technology, Stevinweg 1, 2628CN, Delft, The Netherlands.
Sci Rep. 2024 Jul 31;14(1):17702. doi: 10.1038/s41598-024-66006-z.
Hydrogen sulfide (HS) in environments with temperatures below 100 °C is generally assumed to be of microbial origin, while abiotic HS production is typically restricted to higher temperatures (T). In this study, we report an abiotic process for sulfidogenesis through the reduction of elemental sulfur (S) by hydrogen (H), mediated by pyrite (FeS). The process was investigated in detail at pH 4 and 80 °C, but experimental conditions ranged between 40 and 80 °C and pH 4-6. The experiments were conducted with H as reducing molecule, and µm-sized spherical (but not framboidal) pyrite particles that formed in situ from the HS, S and Fe present in the experiments. Fe monosulfides, likely mackinawite, were identified as potential pyrite precursors. The absence of H production in controls, combined with geochemical modelling, suggests that pyrite formation occurred through the polysulfide pathway, which is unexpected under acidic conditions. Most spherical aggregates of authigenic pyrite were composed of nanometric, acicular crystals oriented in diverse directions, displaying varying degrees of organization. Although it was initially hypothesized that the catalytic properties were related to the surface structure, commercially sourced, milled pyrite particles (< 50 μm) mediated HS production at comparable rates. This suggests that the catalytic properties of pyrite depend on particle size rather than surface structure, requiring pyrite surfaces to act as electron shuttles between S and H.
在温度低于100°C的环境中，硫化氢（HS）通常被认为是微生物来源的，而非生物成因的HS生成通常局限于较高温度（T）。在本研究中，我们报告了一种非生物成因的硫化过程，该过程通过由黄铁矿（FeS）介导的氢气（H）对元素硫（S）的还原作用来实现。我们在pH值为4、温度为80°C的条件下对该过程进行了详细研究，但实验条件范围为40至80°C以及pH值为4 - 6。实验以H作为还原分子，并使用了实验中存在的HS、S和Fe原位形成的微米级球形（而非莓球状）黄铁矿颗粒。单硫化铁，可能是马基诺矿，被确定为潜在的黄铁矿前体。对照实验中未产生H，结合地球化学建模表明，黄铁矿的形成是通过多硫化物途径发生的，这在酸性条件下是出乎意料的。大多数自生黄铁矿的球形聚集体由纳米级针状晶体组成，这些晶体沿不同方向排列，显示出不同程度的组织性。尽管最初假设催化特性与表面结构有关，但商业采购的研磨黄铁矿颗粒（< 50μm）以相当的速率介导了HS的生成。这表明黄铁矿的催化特性取决于颗粒大小而非表面结构，需要黄铁矿表面充当S和H之间的电子穿梭体。
