不同钠吸附比的咸水结冰融水入渗后滨海盐土的水盐分布

在室内利用相同矿化度(10 g·L^-1)、不同钠吸附比(5、10 和30)的咸水进行咸水结冰融水模拟试验、结冰融水入渗和咸水直接入渗的土柱试验, 以淡水处理为对照, 分析不同钠吸附比咸水结冰融水入渗下滨海盐土水盐分布特征。结果表明: 咸水冰融化过程中, 融出水的矿化度和钠吸附比均呈由高到低的变化趋势。咸水结冰融水入渗速度和入渗深度均快于和深于淡水。咸水钠吸附比越小, 结冰融水入渗速率越快、深度越深。水盐分布也表现为低钠吸附比咸水结冰处理的表层土壤含水量较低, 水分向深层迁移, 这种水分分布也使盐分向深层运移, 表现为表层土壤含盐量低, 深层土壤含盐量大。土层含水量低钠吸附比咸水处理高于高钠吸附比处理, 10~45 cm 土层则表现出相反的趋势; 表层土含盐量低钠吸附比处理高于高钠吸附比处理, 且咸水处理下土壤脱盐的深度大于淡水处理。钠吸附比5 的咸水结冰处理, 0~10 cm 土壤平均含水量和含盐量分别为30.3%和1.1 g·kg^-1, 显著低于其他处理。为比较咸水结冰灌溉和咸水直接灌溉的效果, 室内利用含盐量为10 g·L^-1、钠吸附比10 的咸水进行直接入渗的土柱(土壤含盐量为21.3 g·kg^-1)模拟试验, 结果表明: 与咸水直接入渗处理相比, 咸水结冰融水处理盐分淋洗效果更好, 该处理0~25 cm土层平均土壤含盐量为2.9 g·kg^-1, 显著低于咸水直接入渗的10.6 g·kg^-1。

Water and salt distribution in coastal saline soil after infiltration of melt-water of saline water ice with different sodium adsorption ratio

A laboratory soil column experiment was conducted to investigate water and salt distribution in coastal saline soil after saline ice melt-water infiltration. A salinity of 10 g·L^-1 was designed with three variants of saline sodium adsorption ratios (SAR, i. e., 5, 10 and 30) as source water in the experiment, with fresh water as the control. The results showed that both the salinity and SAR levels of melt-water were extremely higher in the initial melt-water than in subsequent melt-waters. The infiltration rate and depth of the saline ice melt-water were higher than those of the control, and increased with the increasing SAR. Soil water content was lower in the 0~10 cm soil layer than in the deep soil after saline ice melt-water infiltration, which resulted in salt content in deep soil was higher than that in surface soil. The depth of soil desalinization was higher under saline ice treatments than the control. Soil water content in the 0~10 cm soil layer was higher in low SAR than in high SAR saline ice treatment. The reverse was, however, noted in the 10~45 cm soil layer. Salt content in the surface soil was lower in low SAR than in high SAR saline ice treatment. Average water and salt contents in 0~10 cm soil layer were 30.3% and 1.1 g·kg^-1 respectively under treatment of SAR 5 saline water. They were lower than in other treatments. To compare effects of saline ice melt-water irrigation with direct saline water irrigation, a simulated column experiment was conducted by using water with 10 g·L^-1 salt and SAR 10. The results showed that compared with the direct saline water irrigation treatment, the saline ice melt-water irrigation treatment presented better soil desalinization effect.