Mercury isotope ratios as a tool to trace and quantify Hg species transformations in contaminated soils and aquifers (MIRACOSA)

汞同位素比作为追踪和量化受污染土壤和含水层中汞形态转化的工具 (MIRACOSA)

• 批准号: 389190907
• 负责人: Professor Dr. Harald Biester, Ph.D.
• 金额: --
• 依托单位: Fachbereich Environmental Geosciences
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/389190907?language=en
• 关键词: Mercury; isotope; ratios; tool; trace

Mercury (Hg) is a toxic pollutant element of great environmental concern. Different Hg species (e.g., Hg(II)Cl2, Hg(0), HgS) exhibit a wide range of physico-chemical properties. Thus, Hg species transformations exert a major influence on the environmental mobility and bioavailability of Hg. However, recognizing such transformations and their significance for Hg in the environment has been challenging. However, in the proposed work we explore the use of Hg isotope fractionation as a novel tool to address this problem. The stable isotope distribution of Hg is altered to a measurable extent during Hg species transformations (e.g., reduction/oxidation, sorption, precipitation, volatilization) may be used to trace Hg dynamics in environmental systems using Hg isotope ratios. Different processes cause characteristic mass-dependent and mass-independent fractionation signatures of Hg isotopes. This allows obtaining new insights into biogeochemical controls of Hg species transformations and potentially quantifying the relative importance of different processes in natural samples. We have selected two field sites in SW-Germany (both Hg-contaminated due to the use of Hg(II)Cl2 in wood impregnation) serving as natural laboratories with a single Hg point source to investigate Hg species transformations and associated Hg isotope fractionation in soil and groundwater systems. We have collected a set of preliminary data identifying the presence of different Hg species and revealing significant Hg isotope variations in soil and groundwater samples. We hypothesize that Hg isotope signatures in soil and groundwater will provide an integrated picture of past and present Hg species transformations and allow tracing processes at solid-solution interfaces and between different solid phase Hg pools. In addition to collecting a large set of field samples, laboratory experiments investigating Hg isotope fractionation during relevant individual processes will be conducted to obtain fractionation factors and mechanisms needed for the interpretation and quantitative description of the field data. Furthermore, a reactive transport model incorporating Hg isotope fractionation between different Hg species will be developed to provide a predictive understanding of Hg plumes in groundwater systems over time. The novel combination of Hg concentration, Hg speciation (using pyrolytic-thermodesorption), and Hg isotope (using cold vapor-MC-ICP-MS) analysis of liquid, solid, and gaseous samples will significantly improve our capability to predict the behavior and fate of Hg not only for the studied field sites but also for other contaminated as well as pristine aquifer and soil systems in general. In contrast to the already documented use source tracer, the application of Hg isotope signatures as process tracer at contaminated sites has not been described yet and no Hg isotope data for groundwater are currently available in the literature.

汞（Hg）是一种有毒的环境污染元素。不同的汞种类（例如，Hg（II）Cl 2、Hg（0）、HgS）具有广泛的物理化学性质。因此，汞的形态转化对汞的环境流动性和生物有效性产生重大影响。然而，认识到这种转变及其对环境中汞的重要性一直是一个挑战。然而，在拟议的工作中，我们探索使用汞同位素分馏作为一种新的工具来解决这个问题。汞的稳定同位素分布在汞物种转化过程中发生了可测量的变化（例如，还原/氧化、吸附、沉淀、挥发）可用于利用汞同位素比追踪环境系统中的汞动态。不同的过程导致特征的质量依赖和质量无关的分馏签名的汞同位素。这使得获得新的见解汞物种转化的地球化学控制和潜在的量化的相对重要性，不同的过程中的天然样品。我们已经选择了两个外地网站在SW-德国（均汞污染，由于使用汞（II）氯化物在木材浸渍）作为天然实验室，一个单一的汞点源，调查汞物种的转换和相关的汞同位素分馏在土壤和地下水系统。我们已经收集了一组初步的数据，确定存在不同的汞物种，并揭示显着的汞同位素变化的土壤和地下水样品。我们假设，土壤和地下水中的汞同位素签名将提供一个综合的图片，过去和现在的汞物种转换，并允许跟踪过程中的固溶界面和不同的固相汞池之间。除了收集大量的现场样品外，还将进行实验室实验，调查相关个别过程中的汞同位素分馏，以获得解释和定量描述现场数据所需的分馏因子和机制。此外，将开发一个反应迁移模型，将不同汞物种之间的汞同位素分馏，以提供一个预测了解汞羽在地下水系统随着时间的推移。汞浓度的新组合，汞的形态（使用热解热解吸），汞同位素（使用冷蒸汽-MC-ICP-MS）的液体，固体和气体样品的分析将显着提高我们的能力来预测的行为和命运的汞不仅为研究现场，但也为其他污染以及原始含水层和土壤系统一般。与已有文献记载的使用来源示踪剂相比，汞同位素特征在污染场地作为过程示踪剂的应用尚未得到描述，文献中目前也没有关于地下水的汞同位素数据。