Abstract: Magnesium oxide dusts produced during calcination fall to the soil surface and easily form magnesian soil crust in magnesite mining area, which would reduce soil porosity, weaken soil infiltration rate, and be harmful to soil quality. Using a soil column leaching device, an experiment was carried out to examine the influence of magnesium oxide dust on soil infiltration and the processes of soil remediation. Soil crust was formed by adding magnesium oxide dust to the soil column, gypsum was used as a modifier to inhibit the formation of crusts, and the morphological changes of soil crusts were observed by scanning electron microscope (SEM). The results showed that the control group after leaching for two times, the soil infiltration rate was stable at 0.367 mm·min^-1. After adding magnesium oxide to the soil, the soil infiltration rate was significantly decreased to 0.214 mm·min^-1. When gypsum and magnesium oxide were combined added into soil column, the soil infiltration rate was stable at 0.425 mm·min^-1 after leaching for two times, suggesting that the soil infiltration rate increased significantly after gypsum addition compared to that contaminated by magnesium oxide dust. The SEM diagram showed that the soil surface after adding gypsum exhibited a reticular structure and that the porosity and stability of the soil surface were improved, which would increase the permeability of the soil.

Key words: aquatic ecosystem, phytoplankton, functional group, Qingshitan Reservoir.