Abstract: Coal mining has great impacts on regional topography, hydrological cycle, soil and vegetation in arid and fragile areas in western China. However, we know less about the influencing scope and extent of open-pit mining on soil properties and bacterial community in the mining area and surrounding environment. In this study, we compared the soil physicochemical properties, bacterial α diversity and bacterial community composition in open-pit mining area and the surrounding areas with different distances from the mining workplace in arid gravel desert area. We further analyzed the relationship among vegetation, soil physicochemical properties, and bacterial communities. The results showed that: (1) Soil bulk density and soluble salts on the dump site were higher than that in the undisturbed area (5000 m away from the mining area), while soil water content, pH, organic matter, total N, and available nutrients were lower than that in the undisturbed area. Compared with the undisturbed area, soil water content, soil bulk density, organic matter, total N, and available N, P and K all decreased within 0-2000 m around the mining area. Soil properties were seriously damaged within the range of 0-500 m around the mining area. Soil nutrients increased at 2000-3000 m around the mining area. There was no significant difference in total N and available N and K beyond 3000 m compared with the undisturbed area. (2) Open-pit coal mining did not affect α diversity of soil bacterial community around the dump site and mining area, but altered bacterial community composition on the dump site and within 0-2000 m around the mining area. Compared with the undisturbed area, the abundance of Actinobacteria and Chloroflexi decreased by 6% and 21%, respectively, while the abundance of Proteobacteria increased by 24% in the dump site. The abundance of Actinobacteria and Chloroflexi increased by 36% and 16%, respectively, while the abundance of Proteobacteria decreased by 58% within the range of 0-500 m around the mining area. Compared with the undisturbed area, the abundance of Actinobacteria and Chloroflexi increased by 19% and 8%, respectively, while the abundance Proteobacteria decreased by 35% within the range of 500-2000 m around the mining area. There was no significant difference in the abundance of soil bacterial communities between 2000-5000 m around the mining area and the undisturbed area. (3) The main environmental factors affecting soil bacterial community composition on open-pit mining area were soil bulk and water content in the dump site and within the range of 0-500 m around mining area, and were organic matter and available nitrogen within the range of 500-2000 m around mining area. Vegetation coverage was the main environmental factor affecting soil bacterial community composition within the range of 2000-5000 m. Soil bulk and organic matter were the main factors affecting the abundance of Actinobacteria and Chloroflexi, whereas soil water content, total nitrogen, and vegetation cover were positively associated with the abundance of Proteobacteria.

Key words: open-pit coal mining, soil physicochemical property, soil bacterial community, arid gravel area, ecological factor