Spatio-temporal distribution characteristics of mercury in soil of Huainan coal mining subsidence area

Taking the soil in the subsidence area of Huainan as the research object, the content of mercury in the samples was tested and analyzed. Combined with the characteristics of pH and organic matter content, the temporal and spatial distribution of mercury in the subsidence area of coal mining area was discussed. The following results were obtained:compared with the soil in the no subsidence area, the soil organic matter in the subsidence area was seriously damaged, with the highest drop of 46%. The content of mercury in soil of subsidence area ranged from 0.013 to 0.050 mg/kg, the average value was 0.027 mg/kg. In 69.7% sampling sites the content of mercury in soil samples exceeded the background value in Huainan City. After 8 years of subsidence, the soil mercury content is the highest, reaching 0.033 mg/kg, which is 1.74 times of the mercury content in the no subsidence area. With the increase of subsidence time, the accumulation of mercury in soil tends to increase. Paddy soil has stronger mercury enrichment capacity and total Hg content higher than that of corn and soybean soil. In the vertical section, the total Hg decreased from the surface downward, and the total Hg and pH showed significantly negative correlation, Hg was significantly positively correlated with organic matter.