Dust emission from different land use types based on the PI-SWERL test

Abstract

Dust emissions have important impacts on the ecological environment and air quality. To explore the underlying mechanisms, characteristics and influence factors of the dust emission from different land use types along the northern dust transport path of Beijing, a portable dust observation instrument (PI-SWERL) was used to test the dust emissions from typical land use types in both the leapfrog mode and progressive mode. The results showed that in the leapfrog mode, the dust emission concentrations (DECs) of the different land use types exhibited four patterns with increasing friction wind speed: fluctuation type, fluctuating growth type, linear growth type and growth stability type. In the progressive mode, the instantaneous dust emission fluxes (IDEFs) from the different land use types under the same friction wind speed exhibited three variation characteristics with increasing erosion time: rapid decline, decline after stabilization, and remaining stable. These variation characteristics preliminarily reflected the dust emission mechanisms and emission potentials of the different land use types. For different land types, the DEFs of grassland after crust destruction (GCD) and vineyard land (VL) were the largest, and the maximum value reached 14 mg/m²·s at a friction wind speed of 0.69 m/s. The DEFs of grassland (TS), stubble land (StL), saline-alkali land (SAL), shrubland (ShL) and grassland with crust (GC) were the lowest, with maximum DEFs of less than 0.3 mg/m²·s. The differences in dust emissions from different land types were mainly affected by the topsoil dust content, soil crust, surface vegetation and human disturbance. Under the influence of various factors, the DEFs of plowed land were 3.62–8.36 times greater than those of unplowed land and 81.78–175.50 times greater than those of grassland at friction wind speeds of 0.39, 0.55 and 0.69 m/s. The DEFs of land after removing stubble were 36.34–164.86 times greater than those of stubble land, and the DEFs of grassland after crust destruction were 50.50–195.25 times greater than those of grassland with crust. In this study, the PI-SWERL dust tests have important reference significance for analyzing dust emission mechanisms, characteristics, potential and effects of human disturbance in different land use types.