Element and isotope composition of light noble gas in marine ferromanganese nodules

The authors have measured element and isotope compositions of He and Ar gases in 10 nodules dredged from Mariana Trough (opening back-arc basin) and the Ogasawara region on the Hakuho Maru Cruise. After being washed with distilled water, samples were dried and preheated in vacuo at 150°C in a gas extraction system for two days to reduce surface air contamination. Each sample was placed in a doublewalled tantalum crucible with a surrounding tantalum heater and extracted gases at 1700°C . Gas purification was carried out by the two-stage Ti/Zr getter. The He-Ne and Ar fractions were separated by use of charcoal traps held at -196°C. The noble gas isotopes were analysed by a single focusing mass spectrometer (6-60-SGA, Nuclide Co.). A resolving power of ~600 at 1% peak height was attained to separate 3He from H3 + HD.

研究人员对“白凤丸”号科考航次中拖网采自马里亚纳海槽（扩张型弧后盆地）与小笠原海域的10个结核样品内氦（He）与氩（Ar）气体的元素及同位素组成进行了测定。样品经蒸馏水清洗后干燥，并置于真空抽气系统内于150℃下预热两天，以降低表面大气污染的干扰。将每份样品置于带有外围钽加热器的双层钽坩埚中，于1700℃下完成气体抽提。气体纯化过程采用两级Ti/Zr吸气剂（two-stage Ti/Zr getter）完成。氦-氖与氩组分通过置于-196℃的活性炭冷阱（charcoal traps）实现分离。稀有气体同位素（noble gas isotopes）采用单聚焦质谱仪（single focusing mass spectrometer，型号6-60-SGA，Nuclide公司）进行分析。在1%峰高条件下可获得约600的分辨率，以将³He与H₃⁺及HD分离开来。