蒸发条件下夹砂层土壤盐离子的迁移特性

Characteristics of saline ions movement in sand-layered soil profiles under evaporation

针对新疆地区大面积盐碱地垦区土壤剖面多呈层状且砂质夹层较多的特点,通过室内土柱模拟试验,研究了蒸发条件下不同层位夹砂层土壤剖面盐离子的动态变化情况。结果表明,砂质夹层对离子运动有较大影响。与均质土相比,层位较低的砂层可以促进盐离子向土表迁移;层位较高的砂层能有效延缓盐离子向土表迁移的速度,并可降低土表盐离子的含量,使得更多的盐离子滞留于砂层以下土壤及土、砂界面处,尤其N a+更是如此;砂层层位越高,其对离子向上迁移的抑制作用越强。最后用回归分析法求得了砂层对C l-和N a+起抑制作用的相对临界层位。

Considering the tact that most soil prohles assume the sand-layered soil in field in XinJiang region in China ,the experiment on the changes of ionic concentration in soil profiles during water evaporation from sand-layered soil with the different sand position was carried out with soil column. The results show that the sand layer in soil profile has an important effect on the Cl^- and Na^＋ movement. When the distances between the sand layer and water table are more than 8 cm and 2 cm respectively,their upward moving velocities and concentrations in soil surface are smaller in layered soil than in the uniform soil ,their concentrations in soil body under sand layer and at the interface between the soil and sand are greater than that in the uniform soil,especially for Na^＋. The relative limited distance （i. e. the ratio of the distance to the buried depth of ground water） where the sand layer will start to restrain the Cl^- and Na^＋ upward movement was calculated by regression analysis.