Influence of Wind Velocity and Soil Size Distribution on Emitted Dust Size Distribution: A Wind Tunnel Study

The question of whether the emitted dust size distribution (EDSD) depends on wind velocity or soil size distribution (SSD) remains to be resolved. This study used wind tunnel tests to investigate the influence of wind velocity and SSD on EDSD. The results showed that EDSD was influenced by both wind velocity and soil texture, supporting the saltation bombardment theory. The ratios of PM2.5 to PM10 (RPM2.5/10) and PM1.0 to PM10 (RPM1.0/10), which reflect the EDSD in the range of 0–10 μm, both showed trends of increase with increasing friction velocity (u*) for all six tested soils. The trend of increase was more significant for RPM1.0/10 than for RPM2.5/10, which indicates that the content of finer dust in the range 0–10 μm increased with increasing u*. When u* increased from 0.51 to 0.68 m s−1, the ranges of increase for RPM2.5/10 and RPM1.0/10 were most significant for sandy soils, followed by sandy loam soils and then loamy soils, indicating that the effect of wind velocity on EDSD increased with increasing sand content in the soils. The EDSD was also influenced significantly by the fully dispersed SSD, especially the sand and silt contents in the soils. The RPM2.5/10 and RPM1.0/10 increased (decreased) logarithmically (linearly) with increasing sand (silt) content in these soils. The finding of this study represents enrichment of data regarding EDSD, which could lead to greater understanding of the roles of wind velocity and SSD in relation to EDSD. Key Points Wind velocity affects emitted dust size distribution, especially for sandy soils Emitted dust size distribution is influenced greatly by fully dispersed soil size distribution, especially the sand/silt contents in soils Content of finer dust in the range 0–10 μm increases with increasing wind velocity and coarsening soil texture at the time of emission