基于CT成像技术的盐渍土壤孔隙结构识别与分析

Characterizing and Analyzing Soil Structure by CT Tomography Technology

为探寻盐渍土土壤孔隙结构与盐分的关系,试验选取6个不同盐分水平(S_1:EC_e=1.51dS/m;S_2:EC_e=4.33dS/m;S_3:EC_e=15.33dS/m;S_4:EC_e=21.31dS/m;S_5:EC_e=28.89dS/m;S_6:EC_e=54.92dS/m)的地块,利用Φ50mm×50mm的PVC管分别采集土样并应用Discovery CT750HD对每个土柱以0.63mm分层进行扫描。通过对获取的连续CT土壤切片的观察并采用python编程调用Arcgis10.1中相应的模块处理并提取出土壤孔隙结构的参数进行分析。结果表明土壤盐分影响孔隙的形成和分布,具体而言,尽管不同盐分水平的土壤孔隙度具有相似的变化趋势,即土层深度大于35mm的孔隙度值明显小于其表层或中间深度的,但当土壤盐分增加到一定程度时(EC_e=54.92dS/m),土壤孔隙度远小于其他5组;土壤孔隙的成圆率表现为S_6最大、S_1最小;而整体的土壤孔隙数以及层间土壤孔隙数随着盐分水平的提高先增加后减小,较高盐分(S_4、S_5)条件下的土壤孔隙数较大,非盐渍土的S_2处理孔隙数最多,高盐条件下S_6的土壤孔隙数最少。

To investigate the effect of salinity on soil structure ,soils samples were taken from six fields with different salinity levels （S1 ：ECe=1 .51 dS/m ;S2 ：ECe = 4 .33 dS/m ;S3 ：ECe =15 .33 dS/m ;S4 ：ECe =21 .31 dS/m ;S5 ：ECe = 28 .89 dS/m ;S6 ：ECe =54 .92 dS/m） using Φ50 mm × 50 mm PVC tubes .CT tomography technology （Discovery CT750 HD） was used to scan each soil sample in the interval of 0 .63 mm .The CT scanning images were analyzed using ARCGIS and Python .Round rate ,porosity ,and pore number were detected .Results indicated that porosity below 35 mm depth was larger than that at surface or medium depth lay‐ers .Furthermore ,high saline soils （ECe =54 .92 dS/m） had smallest porosity and largest round rate ,S1 had the smallest round rate .The number of pore firstly increased and then decreased with salinity .More exactly ,higher saline soils （S4 ：ECe=21 .31 dS/m ,S5 ：ECe=28 .89 dS/m） had larger pore number while high saline soils （S6 ：ECe = 54 .92 dS/m） had smallest pore number ,S2 （ECe=4 .33 dS/m） accounted for the largest value .