Multispecies transport analytical models that solve advection-dispersion equations (ADEs) are efficient tools for evaluating the transport of decaying contaminants and their sequential products. This study develops a novel semi-analytical model to simulate the multispecies transport of decaying contaminants, considering nonequilibrium sorption and decay in both dissolved and sorbed phases. First-order reversible kinetic sorption equations with decay processes are coupled to ADEs. Recursive analytical solutions, using the Laplace transform and generalized integral transform, are developed to address the mathematical complexity of the governing equations. The model's simulation results show excellent agreement with both numerical models and existing analytical solutions. Applied to a four-member radionuclide decay chain, the model reveals that including decay in the sorbed phase results in a lower concentration of the first member and avoids underestimating the radioactivity concentrations of daughter elements. These differences in dissolved radioactivity concentrations between models with and without sorbed phase decay may impact health risk assessments for radioactive waste disposal. Finally, this study provides a more sophisticated mathematical tool for analyzing multispecies transport in real field conditions where nonequilibrium sorption processes predominantly occur.

中文翻译：

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递归分析解决方案，用于同时在溶解相和吸附相中耦合的衰变污染物的非平衡多物种传输


求解平流-扩散方程 （ADE） 的多物种传输分析模型是评估衰变污染物及其连续产物传输的有效工具。本研究开发了一种新的半分析模型来模拟衰变污染物的多物种迁移，同时考虑了溶解相和吸附相中的非平衡吸附和衰变。具有衰变过程的一阶可逆动力学吸附方程与 ADE 耦合。使用拉普拉斯变换和广义积分变换的递归解析解是为了解决控制方程的数学复杂性。该模型的仿真结果与数值模型和现有解析解都非常吻合。应用于四元放射性核素衰变链，该模型显示，在吸附相中包含衰变会导致第一元的浓度降低，并避免低估子元素的放射性浓度。有和没有吸附相衰变的模型之间溶解放射性浓度的这些差异可能会影响放射性废物处置的健康风险评估。最后，本研究提供了一种更复杂的数学工具，用于分析主要发生非平衡吸附过程的实际现场条件下的多物种传输。