Horizontal aeolian sediment flux in the Minqin area, a major source of Chinese dust storms

Minqin has become one of the key dust source areas in China due to its severely degraded eco-environment. However, little is known about how much dust is emitted and transported in this area. Aeolian dust samplers were mounted at 15 heights on a 50 m monitoring tower in Minqin in May 2007 to monitor the horizontal aeolian sediment flux. The monitoring data suggests that the total annual horizontal aeolian sediment flux over Minqin is about 8700 kg m− 1. Of that annual total, the flux in the PM63, PM20, and PM10 size classes amounted to 1730, 780, and 580 kg m− 1 respectively. The flux in May and June accounted for 64% of the annual total, with a minimum in October. The horizontal aeolian sediment flux, including dust flux, decayed rapidly with increasing height following a modified power function, in agreement with the results of several previous studies. The sediment flux in Minqin depends primarily on the wind's characteristics, especially the maximum wind speeds (which create strong aeolian transport). Precipitation in this arid region had limited significance for reducing aeolian sediment transport. The mean diameter, standard deviation, skewness, and kurtosis of the aeolian sediments varied with height, but varied most significantly within 9 m above the surface. The mean diameter of the aeolian sediment ranged from 20 µm (5.6 ø) to 95 µm (3.4 ø), and thus primarily represents suspended dust, even though coarse particles of organic and salt aggregates are also present.