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首页> 外文期刊>Environmental Science & Technology >How Mobile Are Sorbed Cations in Clays and Clay Rocks?
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How Mobile Are Sorbed Cations in Clays and Clay Rocks?

机译：粘土和粘土岩石中被吸附的阳离子的流动性如何？

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摘要

Diffusion of cations and other contaminants through clays is of central interest, because clays and clay rocks are widely considered as barrier materials for waste disposal sites. An intriguing experimental observation has been made in this context: Often, the diffusive flux of cations at trace concentrations is much larger and the retardation smaller than expected based on their sorption coefficients. So-called surface diffusion of sorbed cations has been invoked to explain the observations but remains a controversial issue. Moreover, the corresponding surface diffusion coefficients are largely unknown. Here we show that, by an appropriate scaling, published diffusion data covering a broad range of cations, clays, and chemical conditions can all be modeled satisfactorily by a surface diffusion model. The average mobility of sorbed cations seems to be primarily an intrinsic property of each cation that follows inversely its sorption affinity. With these surface mobilities, cation diffusion coefficients can now be estimated from those of water tracers. In pure clays at low salinities, surface diffusion can reduce the cation retardation by a factor of more than 1000.
机译：阳离子和其他污染物通过黏土的扩散非常重要，因为黏土和黏土岩石被广泛视为废物处理场所的阻隔材料。在这种情况下，进行了有趣的实验观察：通常，痕量浓度的阳离子的扩散通量要大得多，而延迟则要小于基于其吸附系数的预期值。所谓的吸附阳离子的表面扩散已经被用来解释这些发现，但是仍然是一个有争议的问题。而且，相应的表面扩散系数在很大程度上是未知的。在这里，我们表明，通过适当的缩放，可以通过表面扩散模型令人满意地对涵盖广泛范围的阳离子，粘土和化学条件的已发布扩散数据进行建模。被吸附的阳离子的平均迁移率似乎主要是每个阳离子的固有性质，而其固有的性质与其吸附亲和力成反比。利用这些表面迁移率，现在可以从水示踪剂的阳离子扩散系数估算其扩散系数。在低盐度的纯粘土中，表面扩散可将阳离子阻滞降低1000倍以上。

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  • 来源
    《Environmental Science & Technology》 |2011年第4期|p.1443-1449|共7页
  • 作者

    T. Gimmi; G. Kosakowski;

  • 作者单位

    Laboratory for Waste Management, Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland,Institute of Geological Sciences, University of Bern, CH-3012 Bern, Switzerland;

    Laboratory for Waste Management, Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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  • 正文语种 eng
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