Study on Temporal and Spatial Characteristics of Heavy Metal Pollution in Coal Gangue Piles in Mining Area

With the massive mining of coal resources, a large amount of coal gangue has been accumulated on the surface to form gangue hills. Gangue hills encroach on a large amount of land while releasing a variety of harmful heavy metal elements, which can be enriched in the surrounding soil and transmitted in the ecology through the food chain, which will cause harm to the people around the gangue. The distribution of heavy metals in the soil around coal gangue is of great significance to the ecological safety of mining areas. Taking two typical mine gangue piles in a mining area in Shanxi as the research object, based on mathematical statistics, the distribution characteristics of seven heavy metals in the surrounding environment and soil are analyzed. The research results show that the seven heavy metal elements in coal gangue of coal mines A and B are significantly higher than the local background value. Cr has the largest pollution and Hg is the least polluted; the heavy metal pollution content in the downwind area is significantly higher than the heavy metal content in the upwind direction; In the plane direction, the soil heavy metal pollution of coal mine A is significantly higher than that of coal mine B. It is related to the time of coal mine gangue pile stacking; the content of heavy metal elements around the coal mine gangue pile decreases with the increase of the distance from the gangue pile, and their changing trends are different. With the continuous progress of mining activities, the soil around the gangue piles in the mining area can clearly show the characteristics of heavy metal accumulation; the content of heavy metal elements in the soil around the gangue piles of A and B coal mines shows a decreasing trend with the increase of depth. The heavy metal elements in the soil are mainly concentrated in the surface layer of the soil. Coal Mine A has significantly higher heavy metal content coal than Coal Mine B in the section direction.