The volatile fingerprints of life - a new method to indicate the biological or non-biological sources of gas

生命的挥发性指纹——指示气体的生物或非生物来源的新方法

• 批准号: 2759212
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2759212
• 关键词: volatile; fingerprints; life; new; method

Hydrocarbon gases are common in the Cosmos and the geosphere. The biological or non-biological source of hydrocarbon gases is often the subject of debate, the intensity of which depends on the location of the hydrocarbon gas and the amount of information available to settle any uncertainty. Unfortunately, hydrocarbon gases can be relatively information poor compounds. Their small size makes their molecular architecture undiagnostic of source. Patterns of gases with different numbers of carbon atoms do provide some information but the most information rich part of these compounds is within the atoms themselves.The carbon atoms that make up the skeleton of hydrocarbons contain two stable isotopes, carbon-12 and carbon-13. The lighter carbon isotope is more reactive than its heavier counterpart and takes part in reactions more readily. The preferential incorporation of the lighter carbon isotope in reaction product leads to isotope fractionation and can reveal synthetic mechanisms. Non-biological hydrocarbons generally reveal an increase in carbon-12 with carbon number in accord with the kinetically controlled synthesis of higher molecular weight homologues from simpler precursors. By contrast the thermal cracking of high molecular weight biologically-derived hydrocarbons produces the opposite trend where a decrease in carbon-12 with carbon number is observed.This project will explore the compositions and patterns in hydrocarbon gases associated with abiological processes such as adsorption and desorption and compare these to patterns typically associated with life. The product should be improved criteria for distinguishing gas compositional signatures associated with biological or abiological origins. At Imperial College London we have developed a custom-built desorption cell into which powders or plugs of representative samples can be loaded. Known volumes and compositions of gas can be introduced and adsorbed onto the contents and then released by depressurization. Measurement of the gas recovered from the desorption cell is performed using coupled online gas chromatography - flame ionising detector (GC-FID) and online gas chromatography - isotope ratio mass spectrometry (GC-C-IRMS) systems to study molecular weight and stable carbon isotopic fractionation respectively.The results of the project will have implications for the evolution of volatiles and atmospheres in the early solar system, the recognition of gases from any life on Mars and theories of abiotic formation of petroleum deposits on Earth.

碳氢化合物气体在宇宙和地圈中很常见。碳氢化合物气体的生物或非生物来源经常是争论的主题，其强度取决于碳氢化合物气体的位置以及可用于解决任何不确定性的信息量。不幸的是，碳氢化合物气体可能是信息相对贫乏的化合物。它们的小尺寸使得它们的分子结构无法诊断其来源。具有不同碳原子数的气体模式确实提供了一些信息，但这些化合物中信息最丰富的部分是原子本身。构成碳氢化合物骨架的碳原子包含两种稳定的同位素：碳 12 和碳 13 。较轻的碳同位素比较重的同位素更具反应性，并且更容易参与反应。在反应产物中优先掺入较轻的碳同位素会导致同位素分馏，并可以揭示合成机制。非生物碳氢化合物通常表现出碳 12 随碳数的增加，这与从较简单的前体中动力学控制合成较高分子量同系物相一致。相比之下，高分子量生物衍生碳氢化合物的热裂解产生相反的趋势，即观察到碳 12 随着碳数的减少。该项目将探索与吸附和解吸等生物过程相关的碳氢化合物气体的组成和模式并将它们与通常与生活相关的模式进行比较。该产品应改进区分与生物或非生物来源相关的气体成分特征的标准。在伦敦帝国理工学院，我们开发了一种定制的解吸单元，可以将代表性样品的粉末或塞子装入其中。可以将已知体积和成分的气体引入并吸附到内容物上，然后通过减压释放。使用耦合在线气相色谱-火焰离子化检测器 (GC-FID) 和在线气相色谱-同位素比质谱 (GC-C-IRMS) 系统对从解吸池回收的气体进行测量，以研究分子量和稳定碳同位素该项目的结果将对早期太阳系挥发物和大气的演化、火星上任何生命的气体的识别以及地球上石油矿床的非生物形成理论产生影响。