Jin Qusheng, Kirk Matthew F
Department of Earth Sciences, University of Oregon Eugene, OR, USA.
Department of Geology, Kansas State University Manhattan, KS, USA.
Front Microbiol. 2016 Nov 17;7:1696. doi: 10.3389/fmicb.2016.01696. eCollection 2016.
Geological carbon sequestration captures CO from industrial sources and stores the CO in subsurface reservoirs, a viable strategy for mitigating global climate change. In assessing the environmental impact of the strategy, a key question is how microbial reactions respond to the elevated CO concentration. This study uses biogeochemical modeling to explore the influence of CO on the thermodynamics and kinetics of common microbial reactions in subsurface environments, including syntrophic oxidation, iron reduction, sulfate reduction, and methanogenesis. The results show that increasing CO levels decreases groundwater pH and modulates chemical speciation of weak acids in groundwater, which in turn affect microbial reactions in different ways and to different extents. Specifically, a thermodynamic analysis shows that increasing CO partial pressure lowers the energy available from syntrophic oxidation and acetoclastic methanogenesis, but raises the available energy of microbial iron reduction, hydrogenotrophic sulfate reduction and methanogenesis. Kinetic modeling suggests that high CO has the potential of inhibiting microbial sulfate reduction while promoting iron reduction. These results are consistent with the observations of previous laboratory and field studies, and highlight the complexity in microbiological responses to elevated CO abundance, and the potential power of biogeochemical modeling in evaluating and quantifying these responses.
地质碳封存从工业源捕获二氧化碳并将其存储在地下储层中，这是缓解全球气候变化的一种可行策略。在评估该策略的环境影响时，一个关键问题是微生物反应如何响应升高的二氧化碳浓度。本研究使用生物地球化学模型来探究二氧化碳对地下环境中常见微生物反应的热力学和动力学的影响，包括互营氧化、铁还原、硫酸盐还原和甲烷生成。结果表明，二氧化碳水平的升高会降低地下水的pH值并调节地下水中弱酸的化学形态，进而以不同方式和不同程度影响微生物反应。具体而言，热力学分析表明，增加二氧化碳分压会降低互营氧化和乙酸裂解甲烷生成可利用的能量，但会提高微生物铁还原、氢营养型硫酸盐还原和甲烷生成的可用能量。动力学模型表明，高浓度二氧化碳有可能抑制微生物硫酸盐还原，同时促进铁还原。这些结果与先前实验室和现场研究的观察结果一致，并突出了微生物对升高的二氧化碳丰度响应的复杂性，以及生物地球化学模型在评估和量化这些响应方面的潜在作用。
