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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714837
• 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.

了解现代地球热液和极度干旱环境的宜居性和可持续性不仅对于探测当前生物圈的极限很重要，而且对于推断早期地球生命的起源和进化以及在地外行星上寻找生命也很重要。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）的有用形式的可用性，这些元素进一步依赖于这些元素的来源和回收途径。到目前为止，我们对极端条件下这些元素的来源和回收途径的了解非常少。这种知识差距已成为地球化学、矿物学、微生物学、天体生物学、行星科学和环境科学等跨学科研究的焦点，这些研究旨在解开生命起源并寻找外星智慧生命。我们之前的研究基于对加拿大地盾和南非深层地下环境中裂缝水的地球化学研究，表明可以通过流体-岩石相互作用就地提供充足的能源，这些能源以硫酸盐为主，并结合氢气和甲烷。这些黑暗、长期孤立的环境。这种对微生物代谢的能量和营养来源的地质控制很好地解释了地球深层地下独特的生态结构，对于在火星等地外岩石行星上寻找生命具有重要的应用。这项研究提出的自然问题是，是什么控制着地球地下深处的重要金属的循环利用，以及什么控制着类似于早期地球和火星的表面环境中的生命必需元素。在此发现应用中，我们的总体目标是采用强大的稳定同位素工具来研究上述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）海底热液喷口，重点研究正在研究的氮循环； (2) 加拿大地盾和南非地下深层裂缝水，重点关注未经检验的金属循环； （3）陆地热液喷口，以中国西南部腾冲热液田温泉为代表；（4）超干旱环境，以中国西北部柴达木盆地沙漠为代表；后两个将重点对H2O、C、N、S和重要金属进行综合研究。这项研究的结果有望填补各种极端条件下关键生命元素循环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，并为地球生命起源和寻找外星生命提供线索。生活。