Cycles of H2O, C, N, S and vital metals in early-Earth and Mars analog environments: geological control on life in extreme conditions and its insights into origin of life and search for life on extraterrestrial planets

早期地球和火星模拟环境中H2O、C、N、S和重要金属的循环：极端条件下生命的地质控制及其对生命起源和地外行星生命搜寻的见解

• 批准号: RGPIN-2019-06003
• 负责人: Li, Long
• 金额: $ 3.13万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688607
• 关键词: Cycles; H2O; vital; metals; early

The understanding of habitability and sustainability in hydrothermal and hyper-arid environments on modern Earth is important not only for detecting the limit of our current biosphere but also to inferring the origin and evolution of life on early Earth and searching for life on extraterrestrial planets. The habitability and sustainability in these extreme conditions are mainly determined by the availability of the useful forms of life-constituting elements (e.g., H, C, N, S) and vital metals (e.g., Fe, Ca, Cu, Zn), which are further dependent on the sources and recycling pathways of these elements. By far, our knowledge on the sources and recycling pathways of these elements in extreme conditions is very poor. This knowledge gap has become a focused concern in the interdisciplinary research across geochemistry, mineralogy, microbiology, astrobiology, planetary science and environmental science that aim to unravel the origin of life and search for extraterrestrial intelligence. Our previous research, based on geochemical study of the fracture waters in the deep subsurface environments in the Canadian Shield and South Africa, has demonstrated that sufficient energy sources dominated by sulfate coupled by H2 and methane can be supplied in situ by fluid-rock interaction in these dark, long isolated environments. Such a geological control on energy and nutrient sources for microbial metabolism well explains the unique ecological structure in the deep terrestrial subsurface, and has important applications to the search for life on extraterrestrial rocky planets, such as Mars. Natural questions sprouted from this study are, what control the recycling of vital metals in the deep terrestrial subsurface, and beyond, what control the life-essential elements in the surface environments analogue to early Earth and Mars. In this Discovery application, our overall objective is to employ robust stable isotope tools to investigate the sources and recycling processes of the major life-constituting elements and vital metals listed above. We will study four different types of analog environments: (1) submarine hydrothermal vents, focusing on the understudied nitrogen cycle; (2) fracture waters in the deep subsurface in the Canadian Shield and South Africa, focusing on the unexamined metal cycles; (3) terrestrial hydrothermal vents, represented by the hot springs in the Tengchong hydrothermal fields in SW China, and (4) hyper-arid environment, represented by the dessert in the Qaidam Basin in NW China; the latter two will be focused on a comprehensive study on H2O, C, N, S and vital metals. The results of this study are expected to fill some important gaps in the framework of the cycles of crucial life elements in various extreme conditions, help to understand the spatial variations in biodiversity, and shed lights into the origin of life on Earth and search for extraterrestrial life.

对现代地球上水热和高度动脉环境中的可居住性和可持续性的理解不仅对于检测我们当前的生物圈的极限，而且对于推断地球早期生命的起源和进化以及在外星行星上寻找生命的起源和进化。在这些极端条件下的宜居性和可持续性主要取决于生命构成元素（例如H，C，N，S）和重要金属（例如Fe，CA，CU，ZN）的有用形式，这进一步依赖于这些元素的来源和这些元素的回收途径。到目前为止，我们在极端条件下这些元素的来源和回收途径的知识非常差。在地球化学，矿物学，微生物学，天文学，行星科学和环境科学的跨学科研究中，这种知识差距已成为集中的关注，旨在揭示生命的起源并寻求外星智力。我们先前的研究基于对加拿大盾牌和南非深层地下环境中断裂水的地球化学研究，已经证明，在这些黑暗的，长孤立的孤立的环境中，可以通过流体rock相互作用来提供由H2和甲烷耦合的足够的能源。对微生物代谢的能量和养分来源的地质控制很好地解释了深陆地地下的独特生态结构，并且在搜索生命的地面上有重要的应用，例如火星等外星岩石行星。从这项研究中发出的自然问题是，在深层地下及以后的重要金属的回收中是什么控制了地表环境中对早期地球和火星的生活本质上的元素。在此发现应用程序中，我们的总体目标是采用健壮的稳定同位素工具来研究上面列出的主要生命构成元素和重要金属的来源和回收过程。我们将研究四种不同类型的模拟环境：（1）海底热液通风孔，重点是研究的氮循环； （2）加拿大盾牌和南非深处的裂缝水域，重点是未见的金属周期； （3）陆地热液通风孔，以西方西南部坦昌水热场的温泉为代表，以及（4）在中国西北的卡达姆盆地中的甜点代表的高弧环境；后两个将集中于对H2O，C，N，S和重要金属的全面研究。预计这项研究的结果将填补在各种极端条件下关键生命因素周期的框架中的一些重要空白，有助于了解生物多样性的空间变化，并将灯光放到地球上生命的起源并寻求外生物。