Removal of Saline Water due to Road Salt Applications from Columns of Two Types of Sand by Rainwater Infiltration: Laboratory Experiments and Model Simulations
Removal of Saline Water due to Road Salt Applications from Columns of Two Types of Sand by Rainwater Infiltration: Laboratory Experiments and Model Simulations
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DOI：
10.1007/s11270-019-4337-0
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发表时间：
2019-12
期刊：
影响因子：
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通讯作者：
Makoto Higashino;H. Stefan;Daiki Aso
中科院分区：
文献类型：
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作者：
Makoto Higashino;H. Stefan;Daiki Aso
通过模拟和室内实验研究了道路用盐咸水在托尤砂和风化花岗岩砂组成的土柱中的传质和滞留时间。这两种沙都是在日本发现的，特别是风化的花岗岩沙。东友砂粒径较均匀，饱和导水率Ks=0.0296 cm/S，而风化花岗岩沙由13%的细料(粉土和粘土)和87%的粗料(砂和砾石)组成，饱和导水率Ks=0.00393 cm/S。假设雨水渗入土柱产生稳定、均匀的水流，该模型与Toyoua砂土的实验结果吻合较好。从40厘米高的土柱流出的归一化盐分浓度保持不变，直到t=500时，S；然后随着时间的推移，浓度迅速下降，最后接近零。然而，对于风化花岗岩沙，均质流假设下的模型模拟的出水盐分浓度与实验数据不一致。与托尤亚沙子不同的是，盐柱中盐分的质量传输出现了实质性的延迟。这一延迟是由于泥沙和粘土等细小颗粒在土壤中产生的“活跃”和“不活跃的孔隙”的变化。“活跃孔隙”和“不活跃孔隙”的比例不是恒定的，而是随着时间的推移而变化的，这是由于土壤中的物理和/或电化学过程，如孔隙大小分布和盐分的耗竭。提出的修正模型采用了一个时变的活性孔隙参数k(T)，能更好地再现土壤中残留盐量的实验结果。
Mass transport and residence time of saline water from road salt applications in soil columns composed of Toyoura sand and weathered granite sand were investigated by simulations and in laboratory experiments. Both are sands found in Japan, especially the weathered granite sand. The Toyoura sand has a fairly uniform particle size of 0.1 to 0.4 mm diameter, and a saturated hydraulic conductivity Ks= 0.0296 cm/s, while the weathered granite sand used consisted of 13% fine materials (silt and clay) and 87% coarse materials (sand and gravel) with a saturated hydraulic conductivity Ks= 0.00393 cm/s. A model was developed to simulate rinsing of brine from a soil column. Assuming a steady, homogeneous flow induced by rainwater infiltration into the soil column, the model was found to match the experimental results for Toyoura sand very well. The normalized salt concentration in the effluent from the 40 cm tall soil column remained constant until about t = 500 s; the concentration then decreased with time quickly and, finally, approached zero. For the weathered granite sand, however, the salt concentrations in the effluent simulated by the model with assumption of homogeneous flow are inconsistent with the experimental data collected. A substantial delay occurs in mass transport of salt from the column, which is different from the Toyoura sand. The delay is attributed to shifts in “active” and “inactive pores” created in the soil due to fine particles such as silt and clay. The proportion of “active pores” and “inactive pores” is not constant but variable with time due to physical and/or electrochemical processes such as pore-size distributions and salt depletion in the soil. A modified model presented, using a time-variable active pore parameter k(t), can reproduce the experimental results for salt mass left in the soil better.