Effect of coal gangue stockpiling on spatial distribution characteristics and main factors of soil salinity

This study selected coal gangue piles and reclaimed soil of Panyi coal mine in Huainan as research object, the spatial distribution characteristics of soil salinity were investigated during the stockpiling of coal gangue. Mean- while,the simulated rainwater acidity was also determined to test the static immersion. The main factors affecting the dissolution and release of weathered coal gangue were disclosed. The results showed that the average soil salinity con- tent was slightly higher than that of soil background value. In the horizontal direction,the soil salinity content was af- fected by the leaching and migration of the coal gangue piles in the 4 m range around the coal gangue piles. The soil salinity was at slightly salinization level between the 1 m and 2 m at the foot of coal gangue piles. It shaped as V distribution in vertical direction and the average salt contents of soil at different depths were slightly higher than background value. The cations were mainly composed of k+ +Na+ and the anion was mainly HCO- . The composition of soil salinity was characterized by NaHCO3 ,and no significant differences were found for the contents of the same ions between dif- ferent depths. Static immersion experiment of weathered coal gangue showed that the smaller the size of the particle, the faster the TDS dissolution rate,and the salt content in the solution was higher. The variation of TDS value in the immersion was great at different solid-liquid ratios,followed the order of TDS1 ∶ 5 > TDS1 ∶ 3 > TDS1 ∶ 15 > TDS1 ∶ 10 . While at different acidities,those values followed the order of TDS5. 6 > TDS6. 8 > TDS6. 0 > TDS6. 4 . With the increasing tempera- ture of the soaking solution,the smaller the size of the particle it was more influenced by the temperature. Finally,the phytoremediation technology and control measures of soil salinization were discussed. This study provides an important theoretical basis for the ecological reclamation and comprehensive utilization of coal gangue,and also provides an im- portant reference for solving the soil environmental problems in similar mining areas.