土壤大孔隙结构对饱和导水率的影响

[目的]探究土壤不同孔径大孔隙结构特征及数量对土壤饱和导水率的影响,为研究区域土壤水分-溶质迁移规律、水土流失治理与土壤污染防治提供理论参考.[方法]以京郊密云水库五座山林场水源涵养林为研究点,基于工业CT扫描技术,对土柱中土壤大孔隙三维空间结构重建后,探究不同孔径大孔隙结构特征参数密度及数量密度对土壤饱和导水率的影响...

Influence of soil macropore structure on saturated hydraulic conductivity

  Objective  This paper aims to explore the influence of structure and quantity of macropores with different diameter classes on the saturated hydraulic conductivity of soil, and to provide a theoretical reference for the study of soil water solute transport law, soil erosion control and soil pollution control in this area.   Method  The study was carried out on water conservation forest in Wuzuoshan Forest Farm of Miyun Reservoir in Beijing suburb. Based on the industrial CT scanning technology, the three-dimensional spatial structure of soil macropores in the soil column was reconstructed to explore the influence of structural parameter density and quantity density of macropores with different diameter classes on the soil saturated hydraulic conductivity.   Result  (1) Excepting for equivalent diameter large than 4.30 mm, the larger the equivalent diameter of macropores was, the smaller the quantity density and structural parameter density of macropores were. (2) In three soil layers of six sample plots, the proportion of macropores with an equivalent diameter of 0.31?2.30 mm to all macropores was higher than 95%. (3) The maximum saturated hydraulic conductivity of sample plot 1, 2, 5 and 6 was in 0?10 cm soil layer, and it decreased with the increase of soil depth, but except for sample plot 6. The saturated hydraulic conductivity of sample plot 4 increased with the soil depth increasing. (4) Except for the volume density of macropores with an equivalent diameter greater than 4.30 mm, all the other eigenvalue densities of macropores had a significantly positive correlation with the saturated hydraulic conductivity.   Conclusion  (1) In the 0?30 cm soil layer, the saturated hydraulic conductivity of most sample plots decreases with the soil depth increasing, but it possibly increases with the soil depth increasing. (2) The equivalent diameter of macropores in the soil of forest is mainly concentrated in 0.31?2.30 mm, and its occupancy rate is more than 95%. (3) When equivalent diameter of macropores is smaller, the density of characteristic parameter of macropore structure is greater except for the volume and surface area of macropores. (4) There is a significantly positive correlation between the characteristic parameter of macropores and the saturated hydraulic conductivity except for the volume density of macropores with equivalent diameter greater than 4.30 mm. The influence of macropore number on saturated hydraulic conductivity is significantly greater than structure parameters of macropores.