Biogeochemistry of Serpentinizing Systems

人为二氧化碳(CO2)浓度正在上升。我们可以通过将二氧化碳以碳酸盐岩石的形式储存在地下来减少二氧化碳。在地下水中，二氧化碳可以自然地转化为固体碳酸盐，流经富含铁和镁、低硅和低钾(超镁铁质)的岩石。这些反应被称为二氧化碳的碳(C)矿化，它们与蛇纹石化过程有关。蛇纹岩作用是一种水-岩反应，产生的地下水具有非常高的pH值，并富含甲烷(CH4)和氢气(H2)。在蛇纹岩化部位向地下水中注入二氧化碳可增强C矿化作用。然而，人们对超镁铁质次表层的生物地球化学碳循环和深层生物圈知之甚少。我们不知道注入这种二氧化碳是否会导致甲烷的产量增加，这是另一种强大的温室气体。在追踪这个超镁铁系中的C基片、转变和产物方面的纯研究是必需的。此外，蛇纹岩化的地点可以在理解地球上生命的进化和极端环境中的生命方面发挥不可或缺的作用。蛇纹岩化的地点也对寻找其他超镁铁质行星和卫星上的生命感兴趣。因此，我正在进行的研究计划的3个长期目标是：1)量化C交换，并加强大气和超镁铁质岩石之间的C储存；2)确定生命如何在地下蛇纹岩作用的高pH、低营养的极端环境中生存；3)发现可用于确定地球和其他世界蛇纹岩作用地点是否存在现存和化石生命的生物特征。为了促进这些长期目标，在接下来的5年里，我将：1)量化自然的二氧化碳和甲烷通量，并确定如何加强蛇纹岩系统内的二氧化碳封存；2)确定活跃的微生物和病毒群落，以及与蛇纹岩作用相关的地下水中的新陈代谢；以及3)发现蛇纹岩作用地点过去和现在生命的分子和同位素指标。我预计这项研究将有助于：1)减缓气候变化的创新方法；2)在病毒和微生物鉴定、它们的相互作用和碳的微生物新陈代谢方面的新成果；以及3)确定蛇纹岩形成的地点作为宇宙其他地方极端微生物生命的可能地点，并作为空间探索的目标。除了为加拿大减缓气候变化和太空探索的方法做出贡献外，加拿大还将受益于15名高素质人员的化学、生物和地质培训。

Anthropogenic carbon dioxide (CO2) concentrations are on the rise. We can reduce this CO2 by storing it in the ground as carbonate rock. CO2 can be naturally converted to solid carbonate in groundwaters flowing through rocks high in iron and magnesium and low in silica and potassium (ultramafic). These reactions are known as carbon (C) mineralization of CO2, and they are associated with the process known as serpentinization. Serpentinization is a water-rock reaction that produces groundwater with very high pH values and is enriched in methane (CH4) and hydrogen (H2). C mineralization may be enhanced by injecting CO2 into the groundwater at sites of serpentinization. However, the biogeochemical carbon cycling and the deep biosphere in the ultramafic subsurface are poorly understood. We do not know if injecting this CO2 may result in a greater production of CH4, which is another powerful greenhouse gas. Pure research in tracing the C substrates, transformations, and products in this ultramafic system is required. Additionally, sites of serpentinization could play an integral part in understanding the evolution of life on Earth and life in extreme environments. Sites of serpentinization are also of interest to the search for life on other ultramafic planets and moons. Thus, the 3 long-term goals of my ongoing research program are to: 1) quantify C exchange and enhance C storage between the atmosphere and ultramafic rocks; 2) determine how life survives in the high pH, low nutrient extreme environment of subsurface serpentinization; and 3) discover biosignatures that can be used to determine the presence of extant and fossilized life at sites of serpentinization on Earth and other worlds. To contribute to these long-term goals, over the next 5 years, I will: 1) quantify the natural CO2 and CH4 fluxes and determine how to enhance CO2 sequestration within serpentinizing systems; 2) determine the active microbial and viral communities, and the metabolisms within serpentinization-associated groundwaters; and 3) discover molecular and isotopic indicators of past and present life at sites of serpentinization. I anticipate this research will contribute to: 1) innovative methods for climate change mitigation; 2) novel outcomes with respect to viral and microbial identification, their interactions, and microbial metabolism of carbon; and 3) identification of sites of serpentinization as possible loci of extremophile life elsewhere in the universe, and as targets for space exploration. In addition to contributing to Canada's approach to climate change mitigation and space exploration, Canada will also benefit from the chemical, biological, and geological training of 15 highly qualified people.