Collaborative Research: Field and Experimental Iron Isotope Investigation of Sedimentary Pyrite Dissolution in Appalachian Coal Mine Drainage

合作研究：阿巴拉契亚煤矿排水中沉积黄铁矿溶解的现场和实验铁同位素研究

• 批准号: 0229019
• 负责人: Rosemary Capo
• 金额: $ 7.6万
• 依托单位: University of Pittsburgh
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0229019&HistoricalAwards=false
• 关键词: Collaborative; Research; Field; Experimental; Iron

0229019 CapoAcid mine drainage (AMD) from abandoned underground mines is and has long been the most serious water quality and watershed degradation problem in the mining regions of the U.S. As a result of underground coal and metal mining operations, pyrite (FeS2) becomes exposed to water, resulting in its dissolution and release of iron and sulfuric acid to solution, as well as metals and other constituents from acid-induced dissolution of additional minerals. Moreover, a significant fraction of the global fluvial sulfate flux arises from pyrite dissolution, and the contribution is increasing due to mining activities. While pyrite dissolution is of great importance in sulfur cycling and in AMD formation, our understanding of this process and our ability to model it are very limited. This project will exploit recent advances in iron isotope measurement techniques to study pyrite dissolution in a novel manner in the laboratory and in the field. An important objective will be to test and demonstrate the power of using iron isotopes to quantify and source-track the dissolution of pyrite in abandoned coal mine outflows. It is hypothesized that the 56Fe/54Fe isotopic ratio will be distinct for sedimentary pyrites formed under different conditions, and that the process of pyrite dissolution itself could lead to measurable isotopic fractionation. To test this, the 56Fe/54Fe isotopic ratio in sedimentary pyrite from different depositional environments of the Appalachian basin will be determined. The rates of dissolution of some of these samples, and resulting aqueous phase isotopic fractionation, will be investigated in the laboratory using a batch reactor developed specifically for quantifying pyrite dissolution under tightly controlled redox and aqueous phase conditions. The laboratory and field data will allow us to evaluate our ability to use 56Fe/54Fe as a tracer for the primary source of Fe in AMD outflows. Results obtained will provide the basis for moving forward with additional studies of more complex systems, especially systems with bacteria present that can mediate the pyrite dissolution process.

0229019废弃地下矿山产生的碳酸盐矿废水一直是美国矿区最严重的水质和流域退化问题。由于地下煤炭和金属开采作业，黄铁矿(FeS_2)暴露在水中，导致铁和硫酸溶解并释放到溶液中，酸诱导的额外矿物溶解产生金属和其他成分。此外，全球河流硫酸盐通量的很大一部分来自黄铁矿的溶解，而且由于采矿活动，其贡献正在增加。虽然黄铁矿的溶解在硫循环和AMD的形成中非常重要，但我们对这一过程的理解和模拟能力非常有限。该项目将利用铁同位素测量技术的最新进展，在实验室和野外以一种新的方式研究黄铁矿的溶解。一个重要的目标将是测试和展示使用铁同位素来量化和源头追踪废弃煤矿流出物中黄铁矿的溶解的能力。假设不同条件下形成的沉积黄铁矿的56Fe/54Fe同位素比值不同，黄铁矿的溶解过程本身可能导致可测量的同位素分馏。为了验证这一点，将测定来自阿巴拉契亚盆地不同沉积环境的沉积黄铁矿中的56Fe/54Fe同位素比值。其中一些样品的溶解速度和由此产生的水相同位素分馏将在实验室使用专门为在严格控制的氧化还原和水相条件下定量测定黄铁矿溶解而开发的批处理反应器进行研究。实验室和现场数据将使我们能够评估我们使用56Fe/54Fe作为AMD流出物中铁的主要来源的示踪剂的能力。所获得的结果将为进一步研究更复杂的系统提供基础，特别是有细菌存在的系统可以调节黄铁矿的溶解过程。