Near surface halogen (F, Cl, Br, I) cycle

近表面卤素（F、Cl、Br、I）循环

• 批准号: 281601517
• 负责人: Professor Dr. Gregor Markl
• 金额: --
• 依托单位: Arbeitsgruppe Petrologie und Mineralische Rohstoffe
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/281601517?language=en
• 关键词: Near; surface; halogen; Cl; Br

Halogens are omnipresent in nature; the heavier halogens (Cl, Br and I) are commonly regarded as inert tracers in fluid-involving processes in soils and upper crustal rocks. There is, however, increasing evidence that this may not be true and that the halogens record various fluid sources, reactions and precipitation processes in low-temperature environments. These processes are recorded by pyromorphite-group minerals (PyGM), which form by the supergene weathering of Pb ores (e. g., galena) incorporating halogens at the wt.% level. These minerals still form today during near-surface fluid-mediated processes and record the halogen characteristics (e.g., F/Cl, Br/Cl, I/C ratios) of near surface fluids that are involved in their formation at ambient conditions.During the first funding period of the project, the halogen incorporation into PyGM, the behavior of halogens (F, Cl, Br, I) in different depth layers of two soil profiles and in surface waters (precipitation, soil solutions, creek waters and adit waters) was investigated. Furthermore, since adsorption has a major influence on the near surface halogen cycle, we already started to investigate adsorption processes of halogens on different clay mineral fractions. To finish up this project we aim to characterize halogen partitioning between PyGM and fluids of different composition. It is therefore planned 1. to perform a series of experiments and to determine halogen concentrations in freshly precipitated PyGM crystals and in the corresponding fluid from which the crystals precipitated and 2. to finish the determination of halogen concentrations in separated clay fractions from the soil profiles. With this comprehensive data set we will be able to develop a detailed model for halogen distribution, mobilization and important retention processes close to the surface, with a possible application of PyGM as low-temperature fluid monitor.

卤素在自然界中无处不在。较重的卤素（Cl、Br 和 I）通常被视为土壤和上地壳岩石中涉及流体的过程中的惰性示踪剂。然而，越来越多的证据表明这可能不是真的，卤素记录了低温环境下的各种流体来源、反应和沉淀过程。这些过程由磷氯铅矿族矿物 (PyGM) 记录，这些矿物是由含有 wt.% 水平卤素的铅矿石（例如方铅矿）的表生风化形成的。这些矿物至今仍在近地表流体介导的过程中形成，并记录了在环境条件下参与其形成的近地表流体的卤素特征（例如，F/Cl、Br/Cl、I/C 比率）。在项目的第一个资助期间，将卤素纳入 PyGM，研究了卤素（F、Cl、Br、I）在两个土壤剖面的不同深度层和地表水中的行为 （降水、土壤溶液、小溪水和平水）进行了调查。此外，由于吸附对近表面卤素循环有重大影响，我们已经开始研究卤素在不同粘土矿物组分上的吸附过程。为了完成这个项目，我们的目标是表征 PyGM 和不同成分的流体之间的卤素分配。因此，计划 1. 进行一系列实验，测定新沉淀的 PyGM 晶体和沉淀晶体的相应流体中的卤素浓度，2. 完成从土壤剖面中分离的粘土部分中卤素浓度的测定。有了这个全面的数据集，我们将能够开发一个详细的模型，用于卤素分布、移动和靠近表面的重要保留过程，并可能将 PyGM 用作低温流体监测器。