滴灌条件下盐渍土盐分淡化区形成过程中离子运移特征

为了探究滴灌条件下盐渍土壤盐分淡化区形成过程中水盐及离子运动规律,通过土柱滴灌模拟试验分析了土壤水分、盐分及离子的分布特征及随时间的变化关系。结果表明:土壤总盐分及各个离子随着滴灌水的运移而运动,先进行横向运移,再进行纵向移动,当滴灌时间为15 h (滴水量16.2 L·桶^-1)时,在0~30 cm区域内形成稳定的椭圆型离子淡化区,淡化区边缘形成了约10 cm宽的集盐区。在整个运动过程中,表层0~20 cm土层总体上脱盐速率的大小顺序为Cl^->Na⁺>总盐分>SO_4^2-> Mg2> HCO_3~->Ca²⁺>K~+。同时,表层土壤总盐分、Cl~-、SO_4^2-、Na~+的浓度与滴灌时间的函数关系更加符合倒数模型,滴灌后盐分淡化区内土壤的盐分类型由硫酸盐-氯化物型转变为氯化物-硫酸盐型。

Characteristics of salt ion transport during the period of low salt area development in saline soil under drip irrigation

Aiming to understand the movement of water,salt and ions during the low salt area developement in salinity soil under drip irrigation,we analyzed the distribution characteristics of soil moisture,salinity and ions and their relationship with time by a soil column drip irrigation simulation experiment.The results showed that soil total salinity and ions moved transversely first and then longitudinally with drip irrigation.When drip irrigation time was 15 h(drip water 16.2 L·barrel-1),a stable elliptical ion desalination zone was formed in 0~30 cm depth region,and a salt collection area with a width of about 10 cm was formed at the edge of the desalination area.In the whole process of movement,desalination rate at 0~20 cm surface soil layer was in an order of Cl->Na+>total salinity>SO4^2->Mg 2+>HCO3^->Ca^2+>K+.At the same time,the functional relationship between the concentration of total salt,Cl-,SO4^2-,Na+and drip irrigation time was more consistent with the reciprocal model.After drip irrigation,the soil salt type in the desalination area changed from sulfate-chloride type to chloride-sulfate type.