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

锑被列为优先污染物；众所周知，它是有毒的，可能还会致癌。然而，与它的地球化学表亲元素砷相比，这种污染物很少受到关注。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，我建议对这一过程中的矿物产品进行细致的研究，采用补充的大宗分析技术和显微分析技术相结合的方法。我们研究的样本来自斯洛伐克一个废弃的Sb矿床Pezinok附近的两个废物蓄水池。这些样品取自几个钻孔，代表了蓄水池的整个风化剖面，并对As的形态和迁移进行了详细的调查。在拟议的工作中，我们将通过X射线衍射和光学显微镜来确定钻孔样品的整体矿物学。然后将用电子探针分析选定的颗粒的化学成分、晶体结构的微观衍射以及Sb的氧化态的微观X射线吸收(在Sb L边缘)。还将研究合适的大块样品；这些是高达28.3wt%As2O5和2.7wt%Sb的水合三氧化二铁材料。我们将在Sb K边进行体X射线吸收(XAS)实验，以确定这些样品中Sb的局部环境。尤其令人感兴趣的是，当As和Sb同时大量出现时，它们对吸附位置的缔合或竞争。为了补充XAS实验和改善有关Sb形态的信息，我们还将尝试进行批量的121Sb Mössbauer实验。在项目结束时，我们将掌握关于最重要的Sb风化产物的化学成分、晶体结构(或缺乏)以及其中Sb的化学状态的完整数据集。目前缺少这类信息，因为现有研究没有同时使用所有技术，或者从地球化学角度(例如，通过顺序提取)侧重于Sb的形态形成。

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).