Antimony weathering products in mine wastes: A case study in Pezinok (Slovakia)

锑被列为重点污染物；众所周知，它是有毒的，也可能致癌。然而，与它的地球化学表亲砷元素相比，人们对这种污染物的关注很少。在废弃或活跃的矿区，原生Sb矿物（主要是辉锑矿，Sb2S3）形成Sb氧化物，富Sb的水合氧化铁，或将Sb释放到环境中。在这里，我建议对这一过程的矿物产品进行细致的研究，结合互补的体积和微观分析技术。我们研究的样本来自斯洛伐克佩济诺克废弃Sb矿床附近的两个废物蓄水池。样品取自几个钻孔，代表了水库的整个风化剖面，并对砷的物种形成和迁移进行了非常详细的研究。在拟议的工作中，我们将通过x射线衍射和光学显微镜确定钻孔样品的总体矿物学。然后用电子探针分析选定的晶粒的化学成分，用微衍射分析其晶体结构，用微x射线吸收（在Sb L…边缘）分析Sb氧化态。还将研究合适的散装样品；这些是含水氧化铁材料，As2O5高达28.3 wt%， Sb高达2.7 wt%。我们将在Sb K边缘进行体x射线吸收（XAS）实验，以确定这些样品中Sb的局部环境。特别令人感兴趣的是砷和锑在大量同时发生时对吸附位点的结合或竞争。为了补充XAS实验和完善Sb物种形成的信息，我们还将尝试进行大量的121Sb Mössbauer实验。在项目结束时，我们将掌握最重要的Sb风化产物的化学成分、晶体结构（或缺乏晶体结构）以及其中Sb的化学状态的完整数据集。这些信息目前是缺失的，因为现有的研究没有同时使用所有的技术，或者他们侧重于从地球化学的角度来看Sb的物种形成（例如，通过顺序提取）。

Antimony is classified as a priority pollutant; it is known to be toxic and probably also carcinogenic. Nevertheless, little attention is paid to this pollutant in comparison with its geochemical cousin, the element arsenic. At abandoned or active mining sites, the primary Sb minerals (mostly stibnite, Sb2S3) weather to form Sb oxides, Sb-rich hydrous ferric oxide, or to release Sb into the environment. Here I propose a meticulous study of the mineral products of this process by a combination of complementary bulk and micro-analytical techniques. The samples for our study come from two waste impoundments near an abandoned Sb deposit Pezinok in Slovakia. The samples were taken from several boreholes, representing the entire weathering profile of the impoundments, and investigated in a great detail with respect to the speciation and migration of As. In the proposed work, we will determine the bulk mineralogy of the borehole samples by X-ray diffraction and optical microscopy. Selected grains will be then analyzed by an electron microprobe for their chemical composition, micro-diffraction for their crystal structure, and micro-X-ray absorption (at the Sb L,,, edge) for the Sb oxidation state. Suitable bulk samples will also be studied; these are hydrous ferric oxide materials with up to 28.3 wt% As2O5 and 2.7 wt% Sb. We will perform bulk X-ray absorption (XAS) experiments at the Sb K edge to determine the local environment of Sb in these samples. Of particular interest is the association or competition of As and Sb for adsorption sites when they occur simultaneously in large amounts. To complement the XAS experiments and to improve the information on Sb speciation, we will also attempt to carry out bulk 121Sb Mössbauer experiments. In conclusion of the project, we will hold a complete data set on the chemical composition, crystal structure (or lack thereof) of the most important Sb weathering products and the chemical state of Sb within them. Such information is currently missing because the existing studies did not use all techniques simultaneously or they focused on the speciation of Sb from a geochemical point of view (e.g., by sequential extractions).