首页> 外文期刊>Journal of Contaminant Hydrology >Obtaining the porewater composition of a clay rock by modeling the in- and out-diffusion of anions and cations from an in-situ experiment
【24h】

Obtaining the porewater composition of a clay rock by modeling the in- and out-diffusion of anions and cations from an in-situ experiment

机译:通过模拟原位实验中阴离子和阳离子的内外扩散来获得粘土岩石的孔隙水成分

获取原文
获取原文并翻译 | 示例
           

摘要

A borehole in the Callovo-Oxfordian clay rock in ANDRA's underground research facility was sampled during 1 year and chemically analyzed. Diffusion between porewater and the borehole solution resulted in concentration changes which were modeled with PHREEQCs multicomponent diffusion module. In the model, the clay rock's pore space is divided in free porewater (electrically neutral) and diffuse double layer water (devoid of anions). Diffusion is calculated separately for the two domains, and individually for all the solute species while a zero-charge flux is maintained. We explain how the finite difference formulas for radial diffusion can be translated into mixing factors for solutions. Operator splitting is used to calculate advective flow and chemical reactions such as ion exchange and calcite dissolution and precipitation. The ion exchange reaction is formulated in the form of surface complexation, which allows distributing charge over the fixed sites and the diffuse double layer. The charge distribution affects pH when calcite dissolves, and modeling of the experimental data shows that about 7% of the cation exchange capacity resides in the diffuse double layer. The model calculates the observed concentration changes very well and provides an estimate of the pristine porewater composition in the clay rock.
机译:在1年的时间里,对ANDRA地下研究设施的Callovo-Oxfordian粘土岩中的一个钻孔进行了采样并进行了化学分析。孔隙水和井眼溶液之间的扩散导致浓度变化,用PHREEQCs多组分扩散模块对其进行建模。在该模型中,粘土岩石的孔隙空间分为自由孔隙水(电中性)和扩散双层水(不含阴离子)。分别计算两个域的扩散,并同时保持零电荷通量地计算所有溶质的扩散。我们解释了如何将径向扩散的有限差分公式转换为求解的混合因子。运算符拆分用于计算对流和化学反应,例如离子交换以及方解石的溶解和沉淀。离子交换反应以表面络合的形式配制,可以使电荷分布在固定位点和扩散双层上。当方解石溶解时,电荷分布会影响pH值,对实验数据的建模表明,约有7%的阳离子交换容量位于扩散双层中。该模型很好地计算了观察到的浓度变化,并提供了对粘土岩石中原始孔隙水成分的估计。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号