采用二维光学图像和三维断层扫描研究单一粒径土壤团聚体的分形特征  

Study on Fractal Characteristics of a Single Size of Soil Aggregates by Using Two-dimensional Optical Images and Three-dimensional CT Scan Methods

作　　者：马永玉[1] 蒋先军[1] 张维[1] 刘玮[1] 周明厚[1] 

机构地区：[1]西南大学资源环境学院,重庆400716

出　　处：《西南师范大学学报（自然科学版）》2010年第6期73-80,共8页Journal of Southwest China Normal University(Natural Science Edition)

基　　金：国家自然科学基金(40501033);国家"十一五"科技支撑计划基金(2007BAD87B10)

摘　　要：分别通过二维光学图像法和三维X射线断层扫描法计算单一粒径土壤团聚体分形维值.土样采自重庆北碚西南大学稻田垄作免耕长期定位试验点,采用湿筛法对土样进行粒径分级,二维分形特征研究的团聚体粒级分别为：〈0.0 5 3,0.0 5 3-0.2 0 0,0.2 0 0-0.4 5 0,0.4 5 0-1.0 0 mm;CT扫描研究所用原状土样粒级分别为：〈0.0 5 3,0.0 5 3-0.0 2 5,0.0 2 5-1,1-2 mm.结果表明：二维光学图像法得到的单一粒径土壤团聚体孔隙分形维值介于1.1 7-1.5 4;三维X射线断层扫描结果显示团聚体中孔隙分形维值在1.3 5-1.6 5之间,团聚体的分形维数介于2.0 6-2.2 0之间,且分形维数随粒径增大而减小.采用二维光学图像和三维断层扫描均可用于定量研究不同粒径土壤团聚体中孔隙的分形特征,而采用三维X-射线断层扫描可以定量描述单一粒径土壤团聚体的分形特征.The application of fractal theory provides a new method for the quantitative description of soil structure. In this paper, two-dimensional optical images and three-dimensional X-ray tomography methods were used to calculate the fractal dimension of single particle size of soil aggregates. Soil samples were collected from long-term experiment point of combining ridge and no-tillage, Southwest University, Beibei, Chongqing. Wet sieving method was used for particle size classification of soil samples. The aggregate size to be used for two-dimensional fractal fractions were： d0.053 mm, 0.053-0. 200 mm, 0. 200-0. 450 mm, 0. 450-1.00 mm; the soil particle size used for CT scan were d0. 053 mm, 0. 053-0. 025 mm, 0. 025-1 mm, 1-2 ram. The results showed that： By Two-dimensional optical images , fractal dimensions of soil aggregates in single particle diameter ranged between 1.17-1.54; the fractal dimensions of aggregates through three-dimensional X-ray CT scan method was between 2.06-2.20, and the fractal dimension increases with the particle size decreases , but with the porosity increases. Pore fractal dimension value was between 1.35-1.65. Therefore, the two methods both can describe quantitatively the pore fractal characteristics of a particular size of soil aggregates. Three-dimensional CT scan method can describe fractal characteristics of a particular size of soil aggregates quantitatively.

关 键 词：CT扫描 团聚体分形维数 孔隙分形维数 土壤结构 

分 类 号：S152.4[农业科学—土壤学]