Operation of a National Ocean Sciences Accelerator Mass Spectrometry Facility at the Woods Hole Oceanographic Institution

0228996 Hayes这份授予马萨诸塞州伍兹霍尔海洋研究所的为期5年的合作协议为国家海洋科学加速器质谱仪(NOSAMS)设施的继续运营提供支持。NOSAMS提供了自然丰度水平下的14C分析。这些数据对于放射性碳测年、研究地球表面环境的动态地球物理过程(例如海洋环流)以及研究碳的生物地球化学循环都是必不可少的。该设施接受来自所有合格实验室的样本，并根据分析的难度和项目的性质收取不同的费用。在截至2002年3月31日的四年中，该设施完成了18,000多项分析，并从使用费中收回了56%以上的运营成本。该设施提供样品制备服务和14C的定量分析。适合于质谱分析的石墨是从碳酸盐矿物、有机碳或溶解在水中的无机碳的样品中制备的。定量分析使用质谱仪系统，其最小样本量为25微克C。要达到完全精度(14C/12C比为+/-3.5‰)，需要至少500微克C的样本量。在合作协议的五年期间，该设施的能力将得到加强。将安装一个接受气体的离子源，以便能够分析连续流动的载气中的14C。这一发展将为小至0.1微克C的样品提供每小时数十次低精度分析，并将独特地适用于调查和高度稀释的放射性碳示踪剂的监测。沉积物和其他含有有机碳的样品的处理程序将自动化。样品制备实验室应对样品提交激增，从而最大限度地减少周转时间增加的能力将提高。将对质谱仪本身的部件进行改造，以改进和稳定性能。随着这些改进的完成，该设施将继续为海洋科学研究界服务，每年根据需要迅速提供放射性碳分析。*

0228996Hayes This 5-year cooperative agreement award to Woods Hole Oceanographic Institution in Massachusetts provides support for continued operation of the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility. NOSAMS provides analyses of 14C at natural abundance levels. Such data are essential for radiocarbon dating, for studies of dynamic geophysical processes in earth's surface environment (for example, the circulation of the oceans), and for studies of the biogeochemical cycling of carbon. The facility accepts samples from all qualified laboratories and charges fees that vary according to the difficulty of the analysis and the nature of the project. During the four years ending 31 March 2002, the facility completed more than 18,000 analyses and recovered more than 56% of its operating costs from user fees. The facility provides both sample-preparation services and quantitative analyses of 14C. Graphite suitable for mass spectrometric analysis is prepared from samples of carbonate minerals, organic carbon, or inorganic carbon dissolved in water. Quantitative analyses are obtained using a mass spectrometer system for which the minimum sample size is 25 micrograms of C. Attainment of full precision (+/- 3.5 parts per thousand for the 14C /12C ratio) requires a sample size of at least 500 micrograms C. During the five-year period of the cooperative agreement, the capabilities of the facility will be enhanced. A gas-accepting ion source will be installed in order to allow analyses of 14C in a continuously flowing stream of carrier gas. This development will provide tens of low-precision analyses per hour for samples as small as 0.1 micrograms C and will be uniquely applicable to surveys and to monitoring of highly diluted radiocarbon tracers. Procedures for treatment of sediments and other samples containing organic carbon will be automated. The capacity of the sample-preparation laboratory to respond to surges of sample submissions and thus to minimize increases in turnaround time will be increased. Components of the mass spectrometer itself will be rebuilt in order to improve and to stabilize performance. As these improvements are made, the facility will continue to serve the ocean sciences research community, promptly providing radiocarbon analyses as needed each year.***