A Robust and Sensitive In Situ Analyzer for Simultaneous Methane Carbon and Hydrogen Isotopic Measurements in the Deep Sea

尽管经过了几十年的研究，海洋甲烷循环的研究一直受到测量深海巨大压力下溶解气体的困难的阻碍。通过开发能够连续测量甲烷浓度和同位素的新型传感器，该项目旨在更好地了解深海中的甲烷循环和甲烷来源，从而补充对这种温室气体全球动态的了解。最近，基于量子级联激光（QCL）的传感器在苛刻的环境约束下展示了强大，高精度和异常敏感的化学和同位素测量的令人印象深刻的记录。将基于qcl的传感器与透气膜入口相结合，该项目将开发并部署用于深海生物地球化学的原位甲烷同位素传感器。该传感器将与海洋探索信托基金会合作，利用远程呈现探索船（E/V） Nautilus和远程操作车辆（ROV） Hercules在研究巡航中进行现场测试，促进教育工作者、学生和公众同时参与海洋工程、技术、化学、探索和科学。为了设计先进的仪器来研究深海甲烷（CH4）的来源和生物地球化学循环，研究人员将开发一种基于量子级联激光的原位甲烷同位素传感器。通过将基于离轴集成腔输出光谱的方法与量子级联激光器相结合，该传感器将能够测量原位甲烷同位素。该项目的主要目标是演示基于量子级联激光的深海化学传感仪器的使用。为了减少水的干扰，提高原位稳定同位素分析的灵敏度，将采用一种新设计的气体进口系统。传感器系统将使用E/V Nautilus和ROV Hercules在富含甲烷的深海环境中进行现场测试。

Despite decades of research, study of the marine methane cycle has been hindered by the difficulties of measuring dissolved gases at the tremendous pressure of the deep ocean. Through development of new sensors capable of continuous methane concentration and isotope measurements, this project aims to provide a better understanding of methane cycling and methane sources in the deep sea and thereby complements the understanding of global dynamics of this greenhouse gas. Recently, Quantum cascade laser-based (QCL) sensors have demonstrated an impressive track record for robust, highly precise and exceptionally sensitive chemical and isotopic measurements under demanding environmental constraints. Coupling a QCL-based sensor with a gas-permeable membrane inlet, this project will develop and deploy an in situ methane isotope sensor for deep ocean biogeochemistry. The sensor will be field-tested on a research cruise in collaboration with the Ocean Exploration Trust utilizing the telepresence-enabled Exploration Vessel (E/V) Nautilus and the remotely operated vehicle (ROV) Hercules, facilitating the simultaneous engagement of educators, students, and the general public in ocean engineering, technology, chemistry, exploration, and science. In an effort to design advanced instrumentation for studying sources and biogeochemical cycling of methane (CH4) in the deep ocean, the investigators will develop a Quantum cascade laser-based in situ methane isotope sensor. By combining an off-axis integrated cavity output spectroscopy-based approach with Quantum cascade lasers, this sensor will be capable of measuring in situ methane isotopes. A primary goal of this project is to demonstrate the use of Quantum cascade laser-based instrumentation for deep sea chemical sensing. A newly designed gas inlet system will be implemented to reduce interference by water and to enhance the sensitivity of in situ stable isotopic analyses. The sensor system will be field tested at a deep-sea methane-rich environment using the E/V Nautilus and the ROV Hercules.