Changes in isotope ratio and content of dissolved helium through groundwater evolution

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• 作者：Mahara ; Yasunori ; Igarashi ; Toshifumi
• 刊名：Applied Geochemistry
• 出版年：2003
• 期刊代码：5_08832927
• 类别：ce
• 出版时间：May, 2003
• 卷：18
• 期：5
• 页码：719-738
• 文件大小：1009 K

摘要

The dissolved He content and He isotope ratio are proxy indicators of groundwater evolution in the Shimokita peninsula. The record of ³H and excess bomb tritiogenic ³He reveals the intrusion depth of shallow and young groundwater into deep groundwater. The record of tritiogenic ³He suggests that prior to the period of nuclear testing, the natural production level of ³H irradiated by cosmic rays was probably 6 TU. Helium isotope ratios in the groundwater converge to that of the regional crustal He with increasing depth and dissolved He content. The regional degassed He has a ³He/⁴He (R) ratio of 7.24 × 10⁻⁷ which consists of 6%mantle He (with R