土壤薄片中石英颗粒分布的分形特征

Fractal Features of Quartz Size Distribution in Soil Thin Sections

土壤中石英颗粒的粒度分布对揭示母质来源和模拟土壤结构等具有重要意义。本文根据石英的光学性质,利用数字图像处理技术提取土壤薄片中的石英颗粒信息,并应用分形维数来表征土壤薄片中石英颗粒的分布特征。采集免耕和翻耕处理下土壤样品并制作成土壤薄片,利用偏光显微镜和数字图像处理技术提取土壤薄片中石英颗粒,应用Sigma ScanPro5软件统计了石英颗粒的数量、大小和形状等信息,研究土壤薄片中石英颗粒的数量分形特征;并分析了其同石英颗粒数量、面积和平均半径等的关系。结果表明石英颗粒的数量分布具有明显的分形特征,分形维数在1.60～2.18之间,分形维数同薄片中石英颗粒的总面积和平均半径呈负相关。免耕处理下表层土壤石英颗粒的数量分形维数高于底层,而翻耕处理下则呈相反的趋势。免耕和翻耕措施下土壤薄片中石英颗粒的数量分形维数在0～5和10～15cm层次之间没有显著差异,但是在20～25cm层次,翻耕处理分形维数高于免耕处理,说明耕作措施会加速土壤矿物质的风化和破碎并改变石英颗粒在土壤剖面中的分布。

The size distribution of quartz grains in soil is important in revealing the source of parent material and in simulating soil structure. In this study digital image processing method was used to extract the information of quartz grains based on their optical characteristics, and fractal dimension was used to characterize the number-size distribution of quartz grains. Soil samples under no tillage and mouldboard tillage were collected and then soil thin sections were made. Quartz grains in soil thin sections were segmented from cross plain light photographs by image analysis, the number, size and shape of quartz grains were measured with Sigma Scan Pro 5 software. The fractal dimension was calculated and its relations with the total number, total area, and average grain size were analyzed. The number-size distribution of quartz grains showed fractal characteristics with fractal dimensions between 1.60 and 2.18. The fi＇actal dimension was negatively correlated with the total area and the average grain size. No significant difference was found between no tillage and mouldboard tillage treatments.