New Seafloor Sampling Methods for Noble Gases: A Trial at Loihi Seamount

智力价值：这项研究评估了(在船上和实验室)样品采集和处理过程中海底火山玻璃的大气污染的重要性。样本将从夏威夷的洛伊希海山采集，使用一种新开发的气密采样器，消除了暴露在空气中的危险。海底玻璃提供了重要的地幔惰性气体档案，这些稀有气体是地幔脱气和环流的关键指标。不幸的是，重惰性气体的表征，特别是海底玻璃中的Ar和Xe的同位素，一直受到大气污染的阻碍。目前，污染的机理尚不清楚。这项研究验证了这样一种假设，即大多数空气污染是在样品处理和存储过程中引入的，并且可以通过一种新的采样方案来避免，该采样方案包括无空气处理。该项目包括使用加压容器从海底岩石中收集火山玻璃，然后将样品转移到纯氮气大气中，然后进入特殊的真空容器进行分析。稀有气体在实验室粉碎和/或熔化后将用质谱仪进行测量。分析结果将与使用常规方法收集的相同样品的裂解进行比较，即暴露在空气中。实验还将检查污染是否与玻璃泡孔有关。更广泛的影响：主要的更广泛的影响将是为含有惰性气体的海底火山玻璃制定新的无空气采样和分析协议。新设计的取样器可能会应用于其他需要高压密闭采样的领域，如微生物学。工作涉及两个沿海机构的合作，并将支持研究生和本科生的培训。伍兹霍尔海洋研究所将建立一个网站，允许公众查阅研究成果。

Intellectual Merit: This research evaluates the importance of atmospheric contamination of seafloor volcanic glasses during sample collection and processing (both on the ship and in the laboratory). Samples will be collected from Loihi Seamount, Hawaii using a novel, newly developed, air-tight sampler that eliminates exposure to air. Submarine glasses provide important archives of mantle noble gases which are key indicators of mantle degassing and circulation. Unfortunately, the characterization of the heavy noble gases, particularly the isotopes of argon and xenon in submarine glasses has been hampered by atmospheric contamination. At present the mechanism of contamination is unknown. This research tests the hypothesis that most air contamination is introduced during sample processing and storage and that it can be avoided by a new sampling protocol involving air-free handling. The project involves collecting volcanic glasses from rocks on the seafloor using a pressurized vessel and subsequently transferring samples to a pure nitrogen atmosphere and then into special vacuum containers for analysis. Noble gases will then be measured by mass spectrometry after crushing and/or melting in the laboratory. Analytical results will be compared to splits of the same samples collected using conventional methods, i.e. exposed to air. Experiments will also examine whether contamination is related to glass vesicularity. Broader Impacts: The primary broader impact will be the development of new air-free sampling and analytical protocols for seafloor volcanic glasses containing noble gases. The newly designed sampler may have possible application to other fields that require air-tight sampling at high pressures, such as microbiology. Work involves bi-coastal institutional collaboration and will support graduate student and undergraduate training. A website allowing public access to research results will be created at the Woods Hole Oceanographic Institution.