Geochemistry of Metal and Metalloid Thioanions

该项目将探索选定的含水硫代阴离子的地球化学。 硫代阴离子由至少部分被硫离子配位的金属或准金属阳离子组成。 这些阴离子在自然界中的化学行为很少得到研究。 所获得的信息可以在不同领域的应用，如管理固体（包括核）废物，提高我们对成矿的理解，重建过去的氧化还原状态的海洋和愈合沿海ecosystems.Using以前的研究钼的行为在硫化物沃茨为原型，我们将探索机制，触发颗粒协会的Re。 该元素在古环境研究、地质年代学中以及作为核废料成分Tc的实验室模型中引起了人们的兴趣。 在氧化环境中，稳定的形式是强亲水性的ReO 4-。 在亚氧到缺氧的环境中，Re变成颗粒缔合的。 可能引发这种行为变化的机制包括转化为硫代过氧乙酸盐或还原为ReIV复合物。 这部分项目的目标是所形成的产物的性质和表征这种变化的平衡常数。已观察到硫代钼酸盐离子溶解非常不溶性的铁矿物，如黄铁矿。 形成强的Fe-Mo-S络合物暗示。 我们将系统地研究这一现象，以表征溶解的复合物。 如果这种配合物能够与黄铁矿可逆平衡，那么它们可以催化从一硫化铁形成这种矿物。 黄铁矿的形成机制仍然是地球化学家们感兴趣的领域（和一些争议），尽管以前有大量的工作。我们发现CuI和硫代亚砷酸根离子AsS（OH）（SH）-之间存在非常强的络合作用，这引起了理论家的兴趣，并导致了对涉及其他潜在危险金属（例如Pb 2+，Hg 2+）的类似强硫代亚砷酸根络合物的预测。 我们将测试这些预测。 这类络合物导致有害金属和类金属的协同共运输。 在设计危险废物场址和决定疏浚弃渣、尾矿等处置办法时所使用的计算模型中应考虑到这些因素。

HelzEAR-0229387This project will explore the geochemistry of selected aqueous thioanions. Thioanions consist of a metal or metalloid cation coordinated at least partially by sulfide ions. The chemical behavior of these anions in nature has received little study. The information obtained could have applications in such diverse areas as managing solid (including nuclear) wastes, improving our understanding of ore formation, reconstructing the past redox status of the ocean and healing coastal ecosystems.Using previous studies of Mo behavior in sulfidic waters as a prototype, we will explore mechanisms that trigger particle-association of Re. This element is of interest in paleoenvironmental studies, in geochronology and as a laboratory model of the nuclear waste component, Tc. In oxic environments, the stable form is strongly hydrophilic ReO4-. In suboxic to anoxic environments, Re becomes particle-associated. Mechanisms that could trigger this change in behavior include transformation to thioperrhenates or reduction to ReIV complexes. The nature of the products formed and equilibrium constants characterizing such changes are the objective of this portion of the project.Thiomolybdate ions have been observed to dissolve very insoluble Fe minerals, like pyrite. Formation of strong Fe-Mo-S complexes is implied. We will study this phenomenon systematically in order to characterize the dissolved complexes. If such complexes are capable of reversible equilibrium with pyrite, then they may catalyze formation of this mineral from Fe monosulfide. Mechanisms of pyrite formation remain an area of active interest (and some dispute) among geochemists, despite considerable previous work. Our discovery of very strong complexing between CuI and the oxythioarsenite ion, AsS(OH)(SH)-, has sparked interest from theorists and led to predictions of similarly strong thioarsenite complexes involving other potentially hazardous metals (e.g. Pb2+, Hg2+). We will test these predictions. Complexes of this kind result in synergistic co-transport of hazardous metals and metalloids. They should be accounted for in computational models used for designing hazardous waste sites and making decisions about disposal options for dredge spoil, mine tailings, etc.