海涂盐渍土巴氏芽孢杆菌诱导碳酸钙胶结改性试验研究

Modification of Coastal Saline Soil by Calcium Carbonate Cementation Induced by Sporosarcina pasteurii

摘要:

为探究巴氏芽孢杆菌诱导碳酸钙沉淀过程对海涂盐渍土的土壤结构改良效应，设置不同含盐量和不同浓度菌液+胶结液处理，开展巴氏芽孢杆菌诱导碳酸钙胶结改土试验研究。扫描电子显微镜（SEM）分析显示，巴氏芽孢杆菌诱导形成的碳酸钙晶体呈菱形六面体样。X射线衍射分析（XRD）结果显示，在不同处理条件下，巴氏芽孢杆菌均成功诱导胶结生成方解石晶型碳酸钙。高浓度菌液+胶结液施用虽然能生成更多碳酸钙，增强土壤颗粒黏结效果，但这反而削弱了土壤的改良效果。通过巴氏芽孢杆菌诱导的碳酸钙胶结改良土壤中，表层5cm土壤的大团聚体含量（R0.25）、平均质量直径（MWD）和几何平均直径（GMD）均值分别为空白对照组的2.22、1.62、1.24倍。土壤孔隙密度和孔隙率分别为空白对照组的2.37、3.38倍，土壤饱和导水率（Ks）则为3.74倍。这表明该技术有效地改良土壤团聚度和水稳性，优化了土壤孔隙结构，从而显著提高了海涂土壤水分入渗能力。

Abstract:

In order to explore the effects of the technology of calcium carbonate precipitation induced by Sporosarcina pasteurii on the soil structure and water infiltration capacity of coastal saline soil, laboratory tests of calcium carbonate consolidation were carried out by setting different salt content and different concentrations of bacterial solution-cementing fluid as experimental treatment. Scanning electron microscopy (SEM) image results showed that the calcium carbonate crystals induced by Sporosarcina pasteurii were rhombic hexahedral samples, and X-ray diffraction (XRD) results showed that Sporosarcina pasteurii induced cementation to form calcite-type calcium carbonate under different treatments. Because the application of high concentration of bacterial and cementing solution would produce more calcium carbonate, resulting in more obvious adhesion effect of soil particles, but it would weaken the soil improvement effect. The macroaggregate content (R0.25), mean weight diameter (MWD) and geometric mean diameter (GMD) of the surface 5cm soil was improved by Sporosarcina pasteurii, which was induced by calcium carbonate cementation were 2.22, 1.62 and 1.24 times of those of the blank group, respectively, the pore density and porosity were 2.37 and 3.38 times of those of the blank group, respectively, and the saturated hydraulic conductivity (Ks) was 3.74 times, indicating that this technology could improve soil agglomeration and water stability, improve soil pore structure, and thus increase the water infiltration capacity of the coastal soil.