Acquisition of a Continuous Flow Combustion/Gas Chromatography Isotope Ratio Mass Spectrometer for Use in Biogeochemical Cycling and Atmospheric Chemistry Research

通过这项MRI资助，将购买一台稳定同位素比质谱仪，并配备前端配件，包括预浓缩器/低温聚焦系统、毛细管气相色谱系统和微燃烧炉。加州大学欧文分校地球系统科学（ESS）和化学系的几位教职员工将使用该系统，使用气相色谱在线燃烧和/或连续流质谱（GC/C/IRMMS）进行最先进的同位素测量。目前可用的系统没有足够的能力处理所有正在进行的项目。它广泛用于测量空气、土壤和淡水中甲烷、一氧化碳和二氧化碳的同位素比，空气中的一氧化二氮，溶解和颗粒有机碳和无机碳中的海洋碳，珊瑚和土壤有机和无机碳和氮。这些测量包括稳定同位素13 C/12 C、D/H、15 N/14 N和180/160。除了增加容量外，新系统将大大节省与GC/C/IRMMS技术相关的时间，因为它将消除费力的离线样品制备的需要。与IRMS相比，IRMMS的极高灵敏度将允许大气化学和地球化学系统的同位素研究，在这些系统中，很难或不可能获得较大的样品，和/或或感兴趣的物种的丰度非常低，不可能用IRMS仪器测量。这些研究包括分析土壤和高层大气中的甲烷浓度、背景空气中的一氧化二氮、卤代烃和其他非甲烷碳氢化合物。其他项目将包括同位素动力学效应的研究。总体而言，稳定同位素测量正在加州大学欧文分校用于研究越来越多的复杂过程。这些包括生物和非生物环境的隔间之间的转移率，包括碳，氮和其他元素以各种形式的循环，使用痕量气体物种的大气运动，痕量气体及其源和汇的全球预算，以及化学和生物化学反应的机制。和其他科学家将有机会使用这台仪器，并获得宝贵的研究经验。

Through this MRI grant, a stable isotope ratio mass spectrometer will be purchased, complete with front-end accessories including a preconcentrator/cryofocusing system, capillary gas chromatography system, and microcombustion furnace. Several faculty members in the UC Irvine Departments of Earth System Science (ESS) and Chemistry will use this system to make state-of-the-art isotopic measurements using gas chromatography on-line combustion and/or continuous flow mass spectrometry (GC/C/IRMMS). The currently available system has insufficient capacity for all ongoing projects. It is heavily used for isotope ratio measurements of methane, carbon monoxide, and carbon dioxide in air, soil, and freshwater, nitrous oxide in air, ocean carbon in dissolved and particulate organic carbon and inorganic carbon, coral, and soil organic and inorganic carbon and nitrogen. These measurements include the stable isotopes 13C/12C, D/H, 15N/l4N, and 180/160. In addition to increasing capacity, the new system will afford tremendous time savings associated with the GC/C/IRMMS technique because the need for laborious off-line preparation of samples will be eliminated.The extremely high sensitivity of IRMMS compared to IRMS will allow isotope studies of atmospheric chemistry and biogeochemical systems in which larger samples are difficult or impossible to acquire and/or species of interest are in very low abundance and impossible to measure with IRMS instrumentation. These studies include analyses of methane concentrations in soils and in the upper atmosphere, nitrous oxide in background air, halogenated hydrocarbons, and other non-methane hydrocarbons. Additional projects will include studies of kinetic isotope effects. Overall, stable isotope measurements are being used at UC Irvine to study an increasingly large number of complex processes. These include transfer rates among compartments of the biotic and abiotic environment including cycling of carbon, nitrogen, and other elements in various forms, atmospheric motion using trace gas species, global budgets of trace gases and their sources and sinks, and mechanisms of chemical and biochemical reactions.It is anticipated that a large number of principal investigators, but also graduate students, post-doctoral fellows, and other scientists will have access to this instrument and gain valuable research experience.