Experimental Investigation of Organic Synthesis in Submarine Hydrothermal Systems

人们普遍认为，在海底热液系统和火成岩海洋地壳中，非生物合成是有机化合物的广泛来源。然而，除了甲烷可能的例外，从这些环境的样品中从未发现明显具有非生物来源的有机化合物，并且尚未建立区分非生物化合物和来自生物来源的有机化合物的标准。因此，需要实验室研究来确定热液环境中有机合成的特征，以便与自然样品进行比较。本研究是对水热条件下非生物有机合成反应产物进行表征的一系列实验室实验。具体而言，实验包括：(1)研究海洋地壳中哪些矿物能够在什么条件下催化有机合成；(2)表征有机合成产物的组成和相对丰度；(3)测量CO2合成有机产物的同位素分馏；(4)评估产物组成和同位素分馏随温度和CO2/H2比等环境变量的变化情况。这一结果将为今后对热液系统和海洋地壳的有机物的研究提供鉴定非生物化合物的标准。由于非生物有机化合物被认为在这些环境中为微生物提供营养方面发挥着重要作用，因此研究结果也将有助于了解地表和地下生境中异养微生物的分布和丰度。此外，由于热液系统在早期地球和其他行星体上普遍存在，因此结果将有助于解释来自古代热液系统的岩石中有机物的来源，火星样品和陨石。

It is widely thought that abiotic synthesis is a widespread source of organic compounds in submarine hydrothermal systems and the igneous ocean crust. Yet, with the possible exception of methane, organic compounds with a demonstrably abiotic origin have never been identified in samples from these environments, and criteria to distinguish between abiotic compounds and organic compounds derived from biological sources have not been established. Consequently, laboratory studies are required to establish the characteristics of organic synthesis in hydrothermal environments for comparison with natural samples. This research is a series of laboratory experiments that is characterizing the products of abiotic organic synthesis reactions under hydrothermal conditions. In particular, the experiments are: (1) investigating which minerals in the ocean crust are capable of catalyzing organic synthesis and under what conditions, (2) characterizing the composition and relative abundance of organic synthesis products, (3) measuring the isotopic fractionation of organic synthesis from CO2, and (4) evaluating how the product composition and isotopic fractionation vary as a function of environmental variables such as temperature and CO2/H2 ratio. The results will provide criteria that will allow abiotic compounds to be identified in future studies of organic matter from hydrothermal systems and the ocean crust. Since abiotic organic compounds are believed to play a significant role in providing nutrients to microbes in these environments, the results will also help in understanding the distribution and abundance of heterotrophic microbes in surface and subsurface habitats. In addition, since hydrothermal systems were prevalent on the early Earth as well as on other planetary bodies, the results will aid in interpretation of the origin of organic matter in rocks from ancient hydrothermal systems, samples form Mars, and meteorites.