兰州新区灰土次生盐渍化机理

Mechanism of Secondary Salinization of Lime Soil in Lanzhou New Area

为了查明兰州新区灰土地基盐渍化的机理,对兰州新区舟曲中学等场地的素土掺入熟石灰、Ca(OH)_(2)、Mg(OH)_(2)、CaSO_(4)等试剂后进行易溶盐含量分析,同时进行对比发现:石灰的掺入使土体中的可溶性硫酸盐含量显著增大,使土体次生盐渍化;掺入纯Ca(OH)_(2)和Mg(OH)_(2)后土样中硫酸盐含量显著增加,并且与掺入熟石灰的样品中的硫酸盐含量差别不大,这说明灰土盐渍化主要是石灰中Ca(OH)_(2)和Mg(OH)_(2)引起;灰土中可溶性硫酸盐的增加与Ca^(2+)、Mg^(2+)离子对土体中胶体颗粒吸附的阳离子(Na^(+)+K^(+))及阴离子(SO_(4)^(2-)等)的交换作用有关,而土壤胶体吸附的阴阳离子在易溶盐试验制取浸出液时,处于吸附状态的离子不能溶于浸出液,故易溶盐试验检测不到胶体吸附的离子。

In order to find out the mechanism of salinization of lime foundation in Zhouqu Middle School of Lanzhou New Area,soluble salt content analysis and comparison were carried out in the plain soil mixed with hydrated lime,Ca(OH)_(2),Mg(OH)_(2),CaSO_(4) and other reagents.The results showed that:the addition of lime significantly increased the content of soluble sulfate in soil and caused secondary salinization;after the addition of pure Ca(OH)_(2) and Mg(OH)_(2),the sulfate content in soil samples increased significantly,and there was no significant difference between the sulfate content and that in the samples with hydrated lime,indicating that the salinization of lime soil was mainly caused by Ca(OH)_(2) and Mg(OH)_(2) in lime;the increase of soluble sulfate in lime soil is related to the exchange of cation(Na^(+)+K^(+))and anion(SO _(4)^(2-))adsorbed by Ca^(2+)and Mg^(2+)ions to colloidal particles in soil.However,when the soluble salt test was used to prepare the leaching solution,the ions in the adsorbed state could not be dissolved in the leaching solution,so the soluble salt test could not detect the colloid adsorbed ions.