Microscale Distribution of Cesium Sorbed to Biotite and Muscovite

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• 作者：James P. McKinley ; John M. Zachara ; Steven M. Heald ; Alice Dohnalkova ; Matthew G. Newville ; and Steve R. Sutton
• 刊名：Environmental Science & Technology
• 出版年：2004
• 出版时间：February 15, 2004
• 年：2004
• 卷：38
• 期：4
• 页码：1017 - 1023
• 全文大小：1166K
• 年卷期：v.38,no.4(February 15, 2004)
• ISSN：1520-5851

文摘

Individual 1-3 mm biotite and muscovite clasts fromHanford sediment were contacted with 0.08 M CsNO₃.They were examined using electron or X-ray microprobemethods, as intact specimens or sectioned perpendicular totheir basal planes. Cs⁺ was observed to preferentiallysorb to mica edges, steps on mica surfaces, or fracturedregions. The localization of Cs conformed to hypothesizedstrong binding to frayed edge sites in preference to siteson basal planes. In section, Cs⁺ was found to penetratethe mica interior, forming discrete zones of concentration,particularly in muscovite. In biotite, Cs was more abundant,permeating the clasts, but also forming discrete zones ofhigher concentration. Concentrated Cs on both clast edgesand within clast interiors corresponded to microscopicbut relatively extensive zones where K was depleted. Thelocalization of sorbed Cs in areas where K was depletedsuggested that weathering reactions had caused the formationof frayed edge sites within the micas. Cs⁺ accessedcrystal interiors by diffusion along channels following crystaldefects, cracks, or partings where pore fluids hadpreviously migrated to form the interior alteration zones.On the nanometer scale, areas with localized Cs weredisrupted, confirming that frayed edge sites were developedin clast interiors.