北疆典型土壤纵向弥散系数试验

Experimental Study on Longitudinal Dispersion Coefficient of Typical Soil in Northern Xinjiang

【目的】研究不同土壤质地对土壤纵向弥散系数和弥散度的影响。【方法】根据土壤物理学及水动力弥散理论,以新疆北疆较为常见的典型砂壤土、粉壤土、壤土为例,NaCI为示踪剂,采用室内一维土柱垂直入渗试验测定纵向弥散系数。【结果】不同土壤质地,渗流速度越小弥散系数越小,渗流流速越大,达到土壤溶质浓度峰值的时间越短,且峰值浓度越大。砂壤土渗流速为0.020 cm/min,纵向弥散度为2.88 cm;粉壤土渗流速度为0.0181 cm/min,纵向弥散度为3.85 cm;壤土渗流速度为0.011 cm/min最小,纵向弥散度为2.44 cm。【结论】弥散系数和弥散度取决于土壤质地类型与渗流流速。

【Objective】In order to explore the effect of different soil texture on soil longitudinal dispersion coefficient and dispersion degree.【Method】According to the soil physics and hydrodynamic dispersion theory,typical sandy loam,silty loam and loam in northern xinjiang were taken as examples.NaCI was used as tracer and the longitudinal dispersion coefficient of one-dimensional vertical infiltration test was carried out in the laboratory.【Result】Because of the coarse texture of sandy loam,soil compactness is not big,the liquid is easy to diffuse.The smaller the seepage velocity,the smaller the dispersion coefficient,and the larger the seepage velocity,the shorter the time to reach the peak of soil solute concentration,and the larger the peak concentration,and the smaller the vice versa.The seepage velocity of sandy loam was 0.020 cm/min,and the longitudinal dispersion degree was 2.88 cm.The silty loam was 0.018,1 cm/min and the longitudinal dispersion degree was 3.85 cm.The loam seepage velocity was the smallest at 0.011 cm/min,and the longitudinal dispersion degree was 2.44 cm.【Conclusion】The results show that the dispersion coefficient depends on soil texture type and seepage velocity.