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中文摘要：
非均质介质中溶质迁移往往出现非费克现象，传统的对流弥散方程（ADE）则难以较好地描述这种现象。采用连续时间的随机游走理论（CTRW）研究1250cm长-维非均质土柱中溶质运移问题，探讨CTRW模型中参数及非费克迁移的变化特征。研究结果表明，卢值的大小与介质的非均质特征有关，非均质性越强，卢值越小，但卢值具有相对的稳定性。然而ADE的弥散系数则具有随尺度增大而增大的现象。对于介质非均质性较强和非费克现象较明显的溶质穿透曲线，尤其是在拖尾部分，与ADE相比，CTRW具有较高的模拟精度。
英文摘要：
Solute transport in heterogeneous media always occurs in the non-Fickian process with early arrival and long-tail. We analyze the data of the breakthrough curves （BTCs） measured in a 1 250 cm long heterogeneous soil column with the continuous time random walk （CTRW） and the advection-dispersion equation （ADE）. It is found that Fickian behavior occurs in the transport at the distances from the inlet to 100 cm with a β value larger than 2, which is attributable to relatively homogeneous packing. Within the distances from 200 cm to 700 cm, the transport has significant non-Fickian behavior with β= 0.915 ± 0.024, this is due to the highly heterogeneity when packing the column. While the moderate non-Fickian transport is found within the distances from 800 cm to 1200cm, and the β value is 1.19 ± 0.069. Compared with the dispersion coefficient of ADE, β value is relative stable. Better simulation results are also obtained especially for the tails of BTCs by using CTRW with respect to ADE. It implies that CTRW is a useful method to describe the scale-dependent transport and non-Fickian transport.
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