MRI: Acquisition of A New Accelerator Mass Spectrometer for Radiocarbon Measurements

该项目将为伍兹霍尔海洋研究所国家海洋科学加速器质谱设施的新仪器提供资金。 该设施致力于对稀有碳同位素（碳-14或放射性碳）进行高质量测量，可用于对海洋和环境中的碳样本进行测年，并了解自然碳循环。 该设施的使命是为海洋和地球科学界提供高质量的放射性碳测量和专业知识，并开发创新的放射性碳方法。研究人员将购买一种新的最先进的加速器质谱仪（AMS）系统，专门用于不同样品类型的放射性碳测量，包括用于直接测量二氧化碳气体的新接口。购置新仪器将改进所提供的分析服务的性质、质量和数量，并将促进新技术和服务的开发。 获得最先进的设备和技术对于为美国下一代地球和海洋科学家提供高质量的培训和研究工具至关重要。研究人员将使用这些资金购买新系统，并将市售的AMS系统与Ionplus制造的迷你碳测年系统（MICADAS）进行比较，基于记录的精确度和通用气体接口的可用性，其被确定为最合适的。 新开发的气体界面将减少某些样品类型对元素碳（石墨）的需求。新系统将通过提供更高的精度、更高的效率和新的尖端测量选项，改善NOSAMS对科学界的服务。 特别是，最新的AMS系统能够使用混合气体离子源对石墨和相对少量的二氧化碳进行高精度测量。石墨化过程的消除提供了降低空白和每个样品测量成本的潜力。新的AMS系统将增强的应用包括：使用化合物特定放射性碳方法和斜坡热解和氧化测量海水、碳酸盐和复杂有机混合物中的碳-14。NOSAMS的一个核心使命是产生高质量的海水测量结果，以限制海洋混合和通风的时间尺度。 重复的水文研究揭示了海洋混合和通风在十年时间尺度上的可测量变化，包括深海变暖，这对海洋环流，海平面和气候具有重要意义。放射性碳可以提供独立的时间尺度，但需要最高的精度来解决小的变化，以及高通量来实现空间分辨率。 碳酸盐测量能力将通过更高的精度（使用石墨）和更低成本的高采样密度测量（使用中等精度的气体离子源接口）得到加强。化合物特异性放射性碳分析和斜坡热解和氧化可用于确定复杂有机混合物中单个化合物和化合物类别的相对年龄和来源。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will provide funds for new instrumentation at the National Ocean Sciences Accelerator Mass Spectrometry facility (NOSAMS) at Woods Hole Oceanographic Institution. The facility is dedicated to high quality measurements of the rare isotope of carbon (carbon-14 or radiocarbon), which can be used to date carbon samples in the ocean and the environment, and to understand the natural carbon cycle. The mission of the facility is to provide high quality radiocarbon measurements and expertise to the Ocean and Earth science communities and to develop innovative new radiocarbon methods. The researchers will purchase a new state-of-the-art Accelerator Mass Spectrometer (AMS) system designed specifically for radiocarbon measurements in different sample types, including new interfaces for direct measurements of carbon dioxide gas. Acquisition of the new instrumentation will result in improvements to the nature, quality, and quantity of analytical services provided, and will facilitate the development of new techniques and services. Access to state-of-the-art equipment and techniques is crucial to providing high quality training and research tools for the next generation of U.S. based earth and ocean scientists.The researchers will use the funds to purchase a new system, and to compare commercially available AMS systems to the Mini Carbon Dating System (MICADAS), manufactured by Ionplus, which was identified as the most appropriate based on documented precision and the availability of versatile gas interfaces. The newly developed gas interfaces will diminish the need to make elemental carbon (graphite) for some sample types. The new system will improve NOSAMS service to the science community by offering improved precision, greater efficiency, and new cutting edge measurement options. In particular, the newest AMS systems have the capability to produce high precision measurements on graphite and on relatively small amounts of carbon dioxide, using the hybrid gas ion source. Elimination of the graphitization process offers the potential of reduced blank and per-sample measurement cost. Applications that would be enhanced by the new AMS system include: measurements of carbon-14 in seawater, in carbonates, and in complex organic mixtures using Compound Specific Radiocarbon methods and Ramped Pyrolysis and Oxidation. One core NOSAMS mission is to produce high quality sea water measurements to constrain the time scales of ocean mixing and ventilation. Repeat hydrographic studies have revealed measurable changes in ocean mixing and ventilation on decadal time scales, including warming of the deep ocean, which has important implications for ocean circulation, sea level, and climate. Radiocarbon can provide independent time scales, but requires the highest precision to resolve small variations, and high through-put to allow spatial resolution. Carbonate measurement capabilities will be enhanced by higher precision (using graphite) and lower-cost high-sampling-density measurements (using gas ion source interface at moderate precision). Compound specific radiocarbon analysis and Ramped Pyrolysis and Oxidation can be used to determine the relative age and provenance of individual compounds and compound classes in complex organic mixtures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.