摘要
以原状长武黑垆土为研究对象,针对不同输入方式、不同孔隙水流速条件下的氯离子溶质迁移过程,分析原状土壤中大孔隙存在条件下溶质迁移的特征,对两区模型和两流区模型的各拟合参数进行对比和分析。结果表明:大小脉冲输入条件下,氯离子浓度在试验土柱中均随穿透试验的进行呈现先增加而后降低的趋势,其峰值大小及其出现位置随孔隙水流速变化差异显著,且小脉冲输入时溶质穿透曲线较大脉冲时的不对称和拖尾现象更为显著;两流区模型相对于两区模型可较好描述氯离子的穿透曲线;两模型所得模拟参数随孔隙水流速的变化差异性较大。两模型拟合所得弥散度(λ)随孔隙水流速的变化趋势相同,但两流区模型拟合的弥散度大两区模型拟合值2个数量级。两模型拟合所得可动水含量(β)均随孔隙水流速的增加相应增加,而质量交换系数(α)值均极小。
Chloride transport in the typical undisturbed loess soil columns（Changwu black loam soil） was studied.Different input methods and pore water velocities were introduced in order to maintain the chloride transport characteristics in undisturbed soil columns,then the parameters,obtained from two-region model and two-flow domain model,were fitted for further analysis about the preferential flow solute transport in the Loess Plateau soils.The results showed that： Both in the small and large pulse input experiment,chloride concentration in each soil column with the penetration test carried out first increased and then decreased,the peak size and the occurrence were significant,and also the asymmetry and tailing phenomenon of all the solute breakthrough curves with small pulse input were much more obviously than those obtained from the large pulse input.Two-flow model could describe all the chloride breakthrough curves much better than those observed from the two-region model;the difference of simulation parameters both by two-region model and two-flow domain model varied greatly with the increase of the pore water flow velocity.For both the two models,the trend of dispersivity λ,with the changes of pore water velocity was the same,but the fitted values obtained by the two-flow domain model was two times magnitude greater than those by the two-region model.The mobile-immobile partition coefficient（β） fitted with the two models both increased with the increase of pore water velocities.The mass transfer coefficient（α） was quite small fitted with the two models which showed that little mass transfer took place in the undisturbed soil columns of this study.
出处
《水土保持学报》
CSCD
北大核心
2012年第5期224-228,234,共6页
Journal of Soil and Water Conservation
基金
国家“973”计划前期研究专项(2011CB411903)
国家自然科学基金项目(41001132)
第48批博士后基金(20100481351)
关键词
溶质迁移
孔隙水流速
两区模型
两流区模型
solute transport
pore water velocity
two-region model
two-flow domain model
