Environmental Geochemistry of Chromium and Selenium: Spectroscopy, Solution Chemistry, Electrochemistry, and Collaborative Field Studies

9406490 Brown该项目重点关注控制土壤、沉积物和自然沃茨水中铬和硒地球化学行为的因素，特别是那些影响其在常见氧化物和粘土矿物表面吸附的因素。 它集成了磁铁矿，高岭石，蒙皂石的表面地球化学实验室研究和吸附和氧化还原行为的硒对这些矿物和铬的磁铁矿与几个正在进行的磁铁矿和粘土的沉积物中的铬和硒的环境地球化学的实地调查正在进行的助理调查员从美国地质调查局和LBL。 本研究的主要目的是：（1）定量确定Cr（III）和Cr（VI）络合物在磁铁矿上的吸附反应化学计量以及Se（IV）和Se（VI）络合物在磁铁矿、高岭石和蒙皂石上的吸附反应化学计量以及Se（IV）和Se（VI）络合物在磁铁矿、高岭石和蒙皂石上的吸附反应化学计量以及Se（IV）和Se（VI）络合物在磁铁矿、高岭石和蒙皂石上的吸附反应化学计量以及Se（IV）和Se（VI）络合物的几何构型和组成;（3）利用我们的光谱测量结果建立了一个预测铬和硒离子吸附行为和流固分配的宏观模型;（4）研究了两个野外点的自然沉积物和土壤中铬和硒的形态。 拟议的研究建立在NSF资助的过去六年矿物-水界面无机溶质吸附过程的研究基础上，是对涉及氧化还原敏感无机溶质的系统的自然延伸。

9406490 Brown This project focuses on factors that control the geochemical behavior of Cr and Se in soils, sediments, and natural waters particularly those affecting their sorption on the surfaces of common oxide and clay minerals. It integrates laboratory studies of the surface geochemistry of magnetite, kaolinite, and smectite and the sorption and redox behavior of Se on these minerals and Cr on magnetite with several ongoing field investigations of the environmental geochemistry of Cr and Se in magnetite- and clay-bearing sediments being conducted by associate investigators from the USGS and LBL. The objectives of this proposed research are (1) to define quantitatively reaction stoichiometries and the geometry and composition of Cr(III) and Cr(VI) complexes sorbed on magnetite and of Se(IV) and Se(VI) complexes sorbed on magnetite, kaolinite, and smectite; (2) to characterize the magnetite surface before and after sorption using various spectroscopic and scattering techniques; (3) to utilize the results of our spectroscopic measurements in developing a predictive macroscopic model of sorption behavior and fluid-solid partitioning of chromium and selenium ions; and (4) to study the speciation of chromium and selenium in natural sediments and soils from two field sites. The proposed research builds on NSF-funded studies of sorption processes of inorganic solutes at mineral-water interfaces of the past six years and is a natural extension to systems involving redox-sensitive inorganic solutes.