Study of marine carbon cycle based on stable carbon isotopic compositions of amino acids in marine sediments

本研究旨在以氨基酸碳同位素组成为主要工具，阐明海洋沉积物中有机物保存和降解的动力学和机制。这一年，我进一步修改了海洋沉积物样品中氨基酸同位素分析的分析方法。我采用了一种新的高效液相色谱柱，Hypercarb柱，用于氨基酸的分离。最后，我成功地分析了海洋沉积物中单个亲水氨基酸，这是以前的方法无法实现的。我通过测试氨基酸标准来确认分析结果。该方法还显示了其他同位素分析的潜力，如氮同位素和放射性碳，这将有利于未来环境氨基酸的研究。此外，我开发了一种使用手性高效液相色谱柱分离环境样品中单个d -氨基酸的新方法，并证实了稳定碳和氮同位素分析的可靠性。该方法可用于研究海洋沉积物中的d -氨基酸，未来可作为研究海底有机质来源和转化的微生物生物标志物。

This research aims to elucidate the dynamics and mechanism of organic matter preservation and degradation in marine sediments, using carbon isotopic compositions of amino acids as the main tool.In this year, I further modified the analytical method for isotope analyses of amino acids in marine sediment samples. I applied a new HPLC column, Hypercarb column, for the separation of amino acids. Finally, I achieved the successful analyses of individual hydrophilic amino acids in marine sediments, which cannot be achieved by the previous method. I confirmed the analyses by testing amino acid standards. This method also shows the potential for other isotope analyses, such as nitrogen isotope and radiocarbon, which would benefit future researches on environmental amino acids.Furthermore, I developed a new method for the isolation of individual D-amino acids in environmental samples using a chiral HPLC column, and confirmed the reliability of stable carbon and nitrogen isotope analyses. This method can be applied to study the D-amino acids in marine sediments, which can be potentially used as a microbial biomarker to study the sources and transformations of organic matter under the sea floor in the future.