ObjectiveSoil particle size distribution (PSD) significantly affects the intensity of wind erosion. Revealing the changing characteristics of PSD is of great significance for clarifying the migratory process of aeolian sand and its influencing factors.
Method Aeolian topsoil samples of mobile, semi-fixed and fixed sand dunes were selected in Hulun Buir Sandy Land, Inner Mongolia of northern China, and PSD was identified by laser diffraction technique. Soil particle size composition, parameters and grading curve of different sand dune types were calculated and analyzed.
Result The results indicated that: (1) the majority soil particle size in Hulun Buir Sandy Land was occupied by sand particles accounting for 60%−80% of the total volume, while the proportions of clay and silt were much less. During sand dune fixation, clay, silt and extreme fine sand continue to increase significantly (P < 0.05), while fine, medium and coarse sand continue to decrease significantly (P < 0.05). The content of very coarse sand had no significant change (P > 0.05). (2) Soil PSD is comparatively centralized, reflecting a poor sorting, very positive skewness and sharp kurtosis. The fractal dimension of soil PSD increased progressively in range of 2.25−2.49. As the sand dune fixation, the particle size composition was continuously refined, indicating the continuous optimization of the PSD’s symmetry and uniformity. (3) Each frequency curve corresponding to different types of sand dunes had a unique peak. The sorting of soil jump and creep component was more optimized in mobile sand dunes, while the sorting of soil suspend component was more optimized in fixed sand dunes. During the fixation, the intensity of changes in soil particle decreased continuously as the transition occurred between different components.
Conclusion The characteristics of soil PSD varied significantly between different sand dune types in Hulun Buir Sandy Land. This study reveals the variation characteristics of soil PSD during sand dune fixation, and will contribute to the theoretical support desertification control in Hulun Buir Sandy Land.