脱硫石膏对不同质地滨海盐碱土性质的改良效果

Effect to FGD (flue gas desulfurization)-gypsum as an improvement to different coastal saline-alkali soil

研究选取了2种不同质地的滨海盐碱土以及2种不同来源的脱硫石膏,借助土柱淋洗实验方法,分析了不同质地土壤在施加不同石膏后的土壤粒径分布、透气性、水力传导度、pH值以及钠离子累积质量的变化。结果表明:加入脱硫石膏之后,盐碱土中的粘粒比例减少,物理结构得到改善,孔隙度变大,透气性和水力传导能力增强,能够有效加快脱盐过程;比较不同质地的盐碱土改良效果表明,脱硫石膏对粘粒比例较高的土壤改良效果显著强于粘粒比例较低的土壤(p<0.01),施加2.5%石膏,粘粒比例下降6.5%,透气性提高45%,水力传导度增加185%,pH值降低了1.1,钠离子累积质量增加78%,而粘粒比例较低的土壤改良效果要差于粘粒比例高的土壤。比较不同来源石膏对土壤改良效果表明,石膏中的静态溶出率这一性质是决定脱硫石膏对盐碱土改良效果的重要因素,静态溶出率越高,则凝聚更多的带负电荷的粘粒,实现土壤物理结构快速改善。

Two kinds of coastal saline soil and FGD gypsum were used in this experimental study. Changes in soil particle distribution,permeability,and hydraulic conductivity were analyzed using a soil column leaching ex- periment. The results show that after the addition of gypsum,there was a reduction in the percentage of clay,and the physical structure, porosity, permeability, hydraulic conductivity, pH value, and sodium ion cumulative mass were improved;the desalting process was effectively accelerated. A comparison of different kinds of saline soil showed that the improvement effect of gypsum in soil with a high proportion of clay was more significant than in soil with a low proportion of clay （p 〈 0.01 ）. For instance, following the addition of 2.5% gypsum to soil, the proportion of clay decreased by 6.5% , permeability increased by 45% , hydraulic conductivity increased by 185% ,pH value decreased by 1.1 ,and sodium ion cumulative mass increased by 78%. Further, a comparison between different sources of gypsum showed that the static dissolution rate of gypsum is one of the important factors that determine the improvement effect. The higher the static solubility of gypsum, the more negatively charged clay particles that will be gathered,resulting in a rapid improvement in the physical structure of the soil.