| Heavy metal pollution in mining area as a hot issue has being drawn people's attention. After coal-mining subsidence area is reclaimed by coal gangue, the structure and environment of the soil will be changed compare with original. Heavy metal in coal gangue may move to soil, and this may influence the normal use of the soil. This paper choose two reclamation-areas, Panyi mine and Xinzhuang-zi mine in Huainan city, the main works of this paper are as follows.(1) Monitor and analysis pH, available K, organic matter, and six heavy metals of the soil.pH of the soil in the study area presents alkaline. The content of available K in the soil of Panyi reclamation-area is above the fourth level. Available K and organic matter of the soil samples in Xinzhuang-zi reclamation-area are all above the fourth level. Soil samples of these two study areas have a high over standard rate of cadmium, and this rate in Xinzhuang-zi reclamation-area is higher than Panyi reclamation-area. The over standard rates of all the other five heavy metals are zero.(2) Monitor and analysis the coal refuse samples.The nature of the two study areas is difference, this especially reflects at the level of organic matter, chromium and cadmium. As it reference to the level of organic matter, coal refuse in Panyi reclamation-area is higher than the coal refuse in Xinzhuang-zi reclamation-area. Regardless of the level of chromium or cadmium, coal refuses in Xinzhuang-zi are higher than the coal refuse in Panyi reclamation-area.(3) Heavy metal environment quality assessment of the soils in these two reclamation-areas.The environmental quality conditions of the soil in Panyi reclamation-area is within the warning line, and the soil layer of 20-40cm in Xinzhuang-zi reclamation-area has the same level. But the soil layer of 0-20cm and 20-40cm in Xinzhuang-zi reclamation-area attribute to slight pollution level. Panyi reclamation-area is better than Xinzhuang-zi reclamation-area in the environmental quality conditions of each soil layer.(4) Important orders of heavy metals in each soil layer of the study area.The important order of each soil layer in Panyi reclamation-area is Cd>Cr>Ni>Zn>Pb>Cu. The important order of each soil layer in Xinzhuang-zi reclamation-area is Cd>Cr>Ni>Zn>Cu>Pb. Cu has the lowest share rate in Panyi reclamation-area, and Pb has the lowest share rate in Xinzhuang-zi reclamation-area. The key pollutant of these two study areas is Cd, and the followed is Cr.(5) Relevance analysis among the soil heavy metals.In the soil of Panyi reclamation-area, Cu-available K as well as Cu-Cr has significant correlation at 0.01 level, Cr-available K as well as Cr-Ni has significant correlation at 0.05 level. In the soil of Xinzhuang-zi reclamation-area, Cu-organic matter, Zn-available K, Zn-Cu, Cr-Zn, Ni-available K, Ni-Zn, Ni-Cr, Pb-Cu, Pb-Cr, Pb-Ni, Cd-available K, Cd-Zn, Cd-Cr, Cd-Ni as well as Cd-Pb has significant correlation at 0.01 level. Ni-Cu, Pb-available K as well as Pb-Zn has significant correlation at 0.05 level.(6) Relevance analysis between the bottom soil heavy metal and the coal refuse heavy metalIn Panyi reclamation-area, the relevance of Ni has a significant correlation at 0.05 level, the relevance of the other indexes are indistinctively, the related coefficient less than 0, this means one-way migrate of Ni may exist between the bottom soil and coal refuse. In Xinzhuang-zi reclamation-area, the relevance of organic matter has a significant correlation at 0.01 level, the related coefficient less than 0, this means one-way migrate of organic matter may exist between the bottom soil and coal refuse, the related coefficients of the other indexes are small, and the relevance are not significant too.(7) Horizontal distribution and vertical distribution of heavy metals in the soil of study areas.The soil of 0-20cm in Panyi reclamation-area may be polluted by the coal gangue pile. Vertical distributions of Cr and Cd in the soil of study areas are unobvious. Expect the effect of terrain, surrounding environment and human activity, plant species diversity and reclaim period are also effect the distribution.Figure [44] table [29] reference [94]... |
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