Biogeochemistry of Serpentinizing Systems

人为的二氧化碳（CO2）浓度正在上升。我们可以通过将二氧化碳以碳酸盐岩的形式储存在地下来减少二氧化碳。在流经富含铁和镁、低硅和钾（超镁铁）的岩石的地下水中，二氧化碳可以自然转化为固体碳酸盐。这些反应被称为二氧化碳的碳(C)矿化，它们与被称为蛇纹石化的过程有关。蛇纹石化是一种水岩反应，产生的地下水具有很高的pH值，并富含甲烷（CH4）和氢（H2）。在蛇纹石化部位注入CO2可增强地下水中的碳矿化。然而，超镁铁质地下的生物地球化学碳循环和深层生物圈的研究却很少。我们不知道注入这种二氧化碳是否会导致甲烷（另一种强大的温室气体）产生更多。在跟踪C底物，转化和产品的纯研究，在这个超精密系统是必需的。此外，蛇纹石化的地点可以在理解地球上生命和极端环境下生命的进化中发挥不可或缺的作用。蛇纹石化的地点对寻找其他超镁质行星和卫星上的生命也很有兴趣。因此，我正在进行的研究计划的3个长期目标是：1)量化大气和超镁质岩石之间的碳交换和增强碳储存；2)确定生命如何在高pH、低营养的地下蛇纹石化极端环境中生存；3)发现生物特征，这些特征可用于确定地球和其他星球蛇纹石化遗址中现存和化石生命的存在。为了实现这些长期目标，在未来5年内，我将：1)量化自然CO2和CH4通量，并确定如何加强蛇纹石化系统中的CO2固存；2)确定蛇纹石化相关地下水中活跃的微生物和病毒群落以及代谢；3)在蛇纹石化遗址发现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)关于病毒和微生物鉴定、它们的相互作用和微生物碳代谢的新结果；3)确定蛇纹岩化的位点，作为宇宙中其他地方可能存在极端微生物的位点，并作为太空探索的目标。除了有助于加拿大采取减缓气候变化和空间探索的办法外，加拿大还将受益于对15名高素质人员进行化学、生物和地质方面的培训。

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.