日本地球惑星科学連合2015年大会

講演情報

口頭発表

セッション記号 S (固体地球科学) » S-GC 固体地球化学

[S-GC51] 希ガス同位体地球惑星科学の最前線

2015年5月24日(日) 16:15 〜 18:00 A04 (アパホテル&リゾート 東京ベイ幕張)

コンビーナ:*兵藤 博信(岡山理科大学自然科学研究所)、角野 浩史(東京大学大学院理学系研究科附属地殻化学実験施設)、田上 高広(京都大学大学院理学研究科)、座長:兵藤 博信(岡山理科大学自然科学研究所)、角野 浩史(東京大学大学院理学系研究科附属地殻化学実験施設)

17:48 〜 17:51

[SGC51-P02] 熱水の希ガス分析前処理装置の製作と質量分析計の改良

ポスター講演3分口頭発表枠

*佐藤 佳子1熊谷 英憲1岩田 尚能2鈴木 勝彦1高野 進3 (1.海洋研究開発機構海底資源研究開発センター、2.山形大学理学部地球環境学科、3.蒜山地質年代研究所)

キーワード:希ガス, ゲッターポンプ, 海底熱水, 質量分析計, 抽出系

Hydrothermal activity is an essential phenomenon to drive geochemical differentiation on the Earth's surface, which should form polymetallic massive sulfide ores. Noble gas isotopes are regarded to be a powerful tracer even for the geochemical study on hydrothermal activity; however, there are abundant interference volatiles, e.g. halogens and hydrogen sulfide. Here, we designed a new preparation system to remove such volatiles using non-traditional gettering materials. This new preparation system consists of following components: the water preparations system, composite gettering system (halogen getter, sulfide getter and Ti-Zr getter), cryogenic pump, Saes-getter pump and charcoal trap to analyze the all noble gases. The new preparation system has compact volume, which needs small amount of seawater sample of 2-5 cc in volume. It is almost 1/20 compared to the typical requirement for He isotope measurement.

To design new noble gas measurement system in JAMSTEC, another critical problem is to be solved. One of widely used noble gas mass spectrometers, GVI-5400, is now not listed in commercial production models. Thus, all successor models of VG-5400 series have entirely finished their production support since several years ago. However, the VG-5400 series and its successor models still show satisfactory sensitivity and precision to determine noble gas isotope ratios. If we decide to use them much longer, we should maintain their control units, such as power supply, emission control or source control and so on, which requires replacement of essential electrical parts, including vacuum tube (!), regularly. At present, some of these parts are not supplied anymore and we are forced to choose between not replacing them with the new/second-hand electrical parts while they still worked, or renew their electrical circuits with currently manufactured electrical parts. By chance we had started the project to re-use old model of power supply unit. The first trial was applied to the very original VG5400 that was moved from Univ. Tokyo to Yamagata Univ. As the second case, we renewed the power supply and the emission control unit equipped for the JAMSTEC-2 noble gas mass spectrometer (GVI-5400He).

Here we report the better performance of new version of the renewed power supply unit, noiselessness and better stability, with the new noble gas preparation system.