Geochemical Controls on the Composition of Coexisting Vapors and Brines: A Novel Experimental Approach to Assess Aqueous Speciation in Subseafloor Hydrothermal Systems

对共存蒸气和盐水组成的地球化学控制：一种评估海底热液系统中水形态形成的新实验方法

• 批准号: 0351069
• 负责人: William Seyfried
• 金额: --
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-03-15 至 2010-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0351069&HistoricalAwards=false
• 关键词: Geochemical; Controls; Composition; Coexisting; Vapors

Under this funding, the PIs will assess aqueous speciation in coexisting vapors and brines produced during subcritical boiling and supercritical brine condensation. The study will use pH and redox sensors together with a computer controlled Ti-flow reactor, which can maintain constant temperature, pressure and flow rates, while allowing simultaneous investigation of vapor and brine phases. Initially, the experimental study will focus on development of an internally consistent database for aqueous species in the NaCl-H2O system. Although both the vapor and brine phases will be instrumented, it is the vapor phase that will be utilized most to constrain the distribution of aqueous species in the coexisting brine. In effect, the distribution of aqueous species in the vapor buffers that of the brine and provides a novel experimental strategy for determining ion activities in the highly concentrated brine phase. Subsequently, mineral buffers will be added to the system to expand the compositional complexity necessary to model the chemical evolution of vapors and brines in subseafloor hydrothermal systems at mid-ocean ridges. The study will have numerous applications, including the speciation affecting Fe, Cu and Zn mineral solubility in vapors and brines, vapor-brine partitioning of boron and other mobile trace elements during phase separation/segregation processes, and others.

在这笔资金的资助下，PI将评估亚临界沸腾和超临界盐水冷凝过程中产生的共存蒸气和盐水中的水形态。该研究将使用 pH 和氧化还原传感器以及计算机控制的钛流反应器，该反应器可以保持恒定的温度、压力和流速，同时允许同时研究气相和盐水相。最初，实验研究将侧重于开发 NaCl-H2O 系统中水物质的内部一致数据库。尽管蒸气相和盐水相都将被检测，但蒸气相将被最常用于限制共存盐水中水性物质的分布。实际上，蒸汽中水性物质的分布缓冲了盐水中的水性物质的分布，并为确定高浓度盐水相中的离子活性提供了一种新颖的实验策略。随后，矿物缓冲剂将被添加到系统中，以扩大模拟大洋中脊海底热液系统中蒸气和盐水化学演化所需的成分复杂性。该研究将有许多应用，包括影响铁、铜和锌矿物在蒸气和盐水中溶解度的形态，相分离/分离过程中硼和其他移动微量元素的蒸气-盐水分配等。