Identifying the processes that govern the hydrogen isotopic composition of H2 and CH4 in fumarolic emissions: a case study from Nisyros, Greece

确定控制延胡索排放中 H2 和 CH4 氢同位素组成的过程：希腊尼西罗斯的案例研究

• 批准号: 387934778
• 负责人: Professor Dr. Jens Fiebig
• 金额: --
• 依托单位: University of Iceland
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/387934778?language=en
• 关键词: Identifying; processes; govern; hydrogen; isotopic

Previous investigations on discharges from geothermal wells revealed that hydrogen isotope partitioning between H2, CH4 and H2O can reflect aquifer reservoir temperature at depth. However, almost nothing is known about the isotopic equilibration behavior between H2, CH4 and H2O in natural gases ascending through the crust. We seek to analyze the bulk isotopic composition of H2, CH4 and H2O and the clumped isotopic composition of CH4 in volcanic-hydrothermal emissions from Nisyros volcano, Greece, to identify the processes exerting control on the apparent H2-H2O and CH4-H2O hydrogen isotope fractionations and to determine to what extent the bulk and clumped isotopic compositions of hydrothermal CH4 and H2 are reset during their ascent from the reservoir to the venting surface. Such information is required to be able to assess the origin of methane by means of hydrogen and clumped isotope data and to determine the state of volcanic activity by monitoring variations in the chemical and isotopic composition of the gases discharging at the surface.

先前对地热井排放的研究表明，H2、CH4和H2O之间的氢同位素分配可以反映深层含水层温度。然而，对于上升穿过地壳的天然气中 H2、CH4 和 H2O 之间的同位素平衡行为几乎一无所知。我们试图分析希腊尼西罗斯火山热液排放物中 H2、CH4 和 H2O 的大量同位素组成以及 CH4 的聚集同位素组成，以确定控制表观 H2-H2O 和 CH4-H2O 氢同位素的过程分馏，并确定热液 CH4 和 H2 的块体和团块同位素组成在从储层上升到喷口表面的过程中重置的程度。需要这些信息才能通过氢和团块同位素数据评估甲烷的来源，并通过监测地表排放气体的化学和同位素组成的变化来确定火山活动的状态。