Hydrothermal vents and the supply of nutrient metals for the origin and early evolution of life

地球上生命的起源、生存和早期进化，如果存在的话，土卫二上的生命必须需要过渡金属（例如，Ni、Mo、Cu等）。陆壳风化后的河流搬运是现今地球上金属的主要来源，但仅限于早期地球/现今的土卫二。相反，热液喷口（HTV）和/或海底岩石的风化被认为是这些行星体上金属的主要来源，然而，这些喷口中的金属浓度是高度推测性的，不受限制。此外，试图量化地球和土卫二早期海洋中金属含量的现有模型是理论性的，缺乏对关键参数的考虑（例如，有机配体）影响金属溶解度。拟议的研究旨在通过进行热液实验，然后进行热力学和质量平衡（Box）建模，量化早期地球和土卫二上HTV和海洋中的金属含量。这些方法将共同复制早期地壳/土卫二内核与不同压力（P）和温度（T）下相应海水之间的相互作用以及HTV流体与海水的混合。实验将使用包括水热反应器和注射泵的新型装置进行，这将允许在受控的T、P和氧化还原条件下进行多个实验。建模将使用基于计算机的软件进行。拟议的研究将最终能够限制获得的金属浓度（在喷口和海洋中）是否足以触发这些行星体中生命起源和早期进化所需的生物途径。因此，这些结果对于未来以外星生命存在为目标的空间探索至关重要。凭借研究人员和东道方的专门知识以及东道机构的现有设施，该项目可以在拟议时间（24个月）内完成。

The origin, survival, and early evolution of life on the Earth, and if exists, on Enceladus must require transition metals (e.g., Ni, Mo, Cu etc.). Weathering of continental crust followed by riverine transport, which is the main source of metals in the present Earth, was/is limited on the Early earth/present-day Enceladus. Instead, hydrothermal vents (HTVs) and/or weathering of the sub-oceanic rocks are proposed to be the main source of metal on these planetary bodies, however, the metal concentrations in these vents are highly speculative and unconstrained. Furthermore, the existing models that tried to quantify the metal contents in the early ocean on Earth and Enceladus are theoretical and lack the consideration of critical parameters (e.g., organic ligands) that influence metal solubility. The proposed research aims to quantify the metal contents in HTVs and in the ocean on the early earth and Enceladus by performing hydrothermal experiments followed by thermodynamic and mass-balance (Box) modelling. Together these methods would replicate the interaction between early Earth Crust/Enceladus core with corresponding ocean water at various pressures (P) and temperatures (T) and the mixing of HTV fluids with ocean water. Experiments will be performed using novel set-up comprising hydrothermal reactor and syringe pump, which will allow performing multiple experiments in controlled T, P, and redox conditions. The modelling will be done using computer-based software. The proposed research will finally be able to constrain if obtained metal concentrations (in vents and ocean) are sufficient to trigger biologic pathways required for the origin and early evolution of life in these planetary bodies. The results are therefore critical for future space exploration targeting the existence of extra-terrestrial life. With the expertise of the researcher and the host, available facilities at the host institution, the project can be finished within proposed time (24 months).