Abstract:  

To reveal the characteristic of particle size distribution (PSD) of Aeolian soils and the influence factors at the Mu Us Sandy Land,which is between Shaanxi Province and Inner Mongolia,China,the soil PSD were identified from the mobile,semi-fixed and fixed dunes using laser diffraction technique.Subsequently,soil PSD parameters and curves were calculated including average particle size,standard deviation,skewness,kurtosis and frequency distribution and cumulative curves.The results indicated as follows: (1) fine sand was the dominative group accounting for 29.89% up to 32.46% of the total volume in the Mu Us Sandy Land and there were no significant differences between different types of dunes (P >0.05).Accordingly,coarse sand,clay and extreme coarse sand were much less.For clay and coarse sand,there was no significant difference between mobile,semi-fixed and fixed dunes (P >0.05).However,the content of clay particles was increased significantly and the content of coarse sand was decreased significantly from semi-fixed and fixed dunes (P <0.05).Furthermore,the content of extreme coarse sand was significantly decreased from mobile and fixed dunes (P <0.05).(2) The average particle size was 3.35 Φ in the Mu Us Sandy Land.Soil particle size distributions were centralized,which reflected a poor sorting capability,a very positive skewness and sharp kurtosis.During the sand dune fixation,there was no significant difference in average particle size and standard deviation (P>0.05).Nevertheless,kurtosis became significantly wider (P<0.05).For the semi-fixed dunes,the skewness was inclined to negative if compared with the other two types of dunes.(3) The particle size of the saltation in the mobile,semi-fixed and fixed dunes was 44-435,63-500 and 31-354μm,respectively,which indicated strongest Aeolian movement in the semi-fixed dunes.In the Mu Us Sandy Land,the dominative particles were primarily affected by sand source,while the minorities were mainly influenced by the mobility of sand dunes.The intensity of sand transport was growing first and then reducing as the sand dune got fixation.This information from this study will contribute to reveal the sand transport during the sand dune fixation,and provide firm basis for ecological restoration in desertified areas.

Key words: particle size distribution')">particle size distribution, particle size parameter, Aeolian sand transport, particle grading curve, Mu Us Sandy Land