Abstract Hydraulic fracking is used to enhance the production of tight gas reservoirs. Because shale reservoirs can contain toxic elements (metals and radionuclides), the release rates of these elements must be quantified in order to determine the possible environmental impact of fracking. This paper is devoted to the complete and precise determination of the mineralogy of the Alum Shale in Denmark, which is known for its high content of gaseous hydrocarbons. Its metal-bearing phases are identified and quantified using complementary analytical techniques (i.e., X-ray diffraction, electron microscopy and electron probe analysis, and X-ray tomography). A detailed quantitative mineralogical composition is calculated using three different approaches (i.e., matrix inversion, quantitative X-ray diffraction, and the MQ program), which is then used to determine the quantity of polluting elements in each phase. Pyrite (FeS2) is the major metal-bearing phase (e.g., As, Cu, Co, Ni, Pb, Zn, V, U). Elements such as V, Ra, Cs, Be, Cr, Ba are trapped in clay minerals, whereas U, Cd, Mo, and Hg are present in organic matter. It is essential to better identify toxic element-bearing phases to formulate fracking fluids with the lowest possible chemical reactivity in order to avoid the release of pollution by flowback waters.

中文翻译：

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丹麦明矾页岩中的金属和放射性核素 (MaR)：识别含 MaR 的相以更好地管理水力压裂水

摘要 水力压裂用于提高致密气藏的产量。由于页岩储层可能含有有毒元素（金属和放射性核素），因此必须量化这些元素的释放速率，以确定压裂可能对环境造成的影响。本文致力于完整和精确地测定丹麦明矾页岩的矿物学，该页岩以其高含量的气态烃而闻名。其含金属相使用补充分析技术（即 X 射线衍射、电子显微镜和电子探针分析以及 X 射线断层扫描）进行鉴定和量化。使用三种不同的方法（即矩阵反演、定量 X 射线衍射和 MQ 程序）计算详细的定量矿物组成，然后用于确定每个阶段中污染元素的数量。黄铁矿 (FeS2) 是主要的金属相（例如 As、Cu、Co、Ni、Pb、Zn、V、U）。V、Ra、Cs、Be、Cr、Ba 等元素被困在粘土矿物中，而 U、Cd、Mo 和 Hg 则存在于有机质中。必须更好地识别含有毒元素的相以配制化学反应性尽可能低的压裂液，以避免回流水释放污染。