Grain Size Characteristics from Dry Playa
Chagan Nur in northern China

Dry salt lakes are widely distributed in semi-arid regions. Dry lake beds have been found to have a greater capacity to release dust. However, the particle size characteristics of dry lakebed soils have rarely been studied. To reveal the soil grain size characteristics, we used surface and subsurface soil from dry lake beds in semi-arid regions with different soil crusts as the object of study. We used particle size parameters and class-standard deviation methods to study the particle size variation patterns and the degree of variability. The results show that the dry lake was mainly composed of clay (1.36%-43.96%) and silt (5.5%-67.94%) particles. Soil particle characteristics show the Mean size (Mz) of (0.65-8.89 φ), poorly sorted (0.79-3.38 φ) and a clear linear relationship between dry lake bed skewness and sorting. There is a high variability between soil particle size fractions across the lake bed, with soil crusts and soil moisture protecting the loss of subsurface soil particles, hence the differences between surface and subsurface soil particles. However, the destruction of the soil crust and the evaporation of soil moisture accelerates the wind erosion of the subsurface soil particles. In the dry lake area, vegetation construction has promoted the accumulation of sand content (73.28% -93.08%). We found that the fractions 0.19-9.15 µm, 9.15-36.99 µm, 36.99-366.93 µm, and 366.93-1214.72 µm are susceptible to respond to environmental changes and contribute to dust storms. Therefore, local governments should treat and manage dried-up lakes to reduce the impact of salt dust on the ecosystem.