| The coal resource is the important material base for the human survival and development.There were many eco-environmental problems after the large-scale mining and using coal.Such as, a lot of coal gangue occupied farmland, forest and residential land; fly ash pollutedair and water; land subsidence caused all sorts of geological disaster, etc. All of these hadbrought serious impact for the local people's normal production and living. In order to providea theoretical basis for the restoration of mine eco-environment, the soil physicochemicalproperties and pollution of coal wasting lands were analyzed.In the paper, the soil physicochemical analysis method was used to determine andanalyze the soil physicochemical properties and the change of the heavy metal content duringthe gangue field in Sanlidong coal mine in Tongchuan and its surrounding areas. The mainresults were summarized as follows:(1)In the gangue field, the soil quality had improved with the increasing time length ofdischarging the gangue. The soil moisture and pH value were increased. The content ofwater-soluble salts was reduced. The soil maturation degree was higher. The soils weatheredchanged gradually from sandy loam to loam. The content of soil organic matter, N, P and Kwere also gradually improved. The indexes of physicochemical were all well developed. Thesoil moisture in lower slope was higher than upslope. The pH value in upslope and platforminside was higher. The content of water-soluble salts in lower slope and platform outside washigher. The content of soil organic matter, N, P and K in the gangue field were lower than itssurrounding areas.(2) In the gangue field, the content of heavy metal overall gradually reduced with theincreasing length of discharging the gangue, the changes law of Cu, Cd and Zn were mostsignificant. The heavy metal more easily accumulates in the lower slope, so the content ofheavy metal in the lower slope was higher than the other sites. The content of soil heavy metalin the surrounding areas of the gangue field was also affected by the gangue field, mainlyreflects in the channel and the wind. The heavy metal spread to the surrounding areas by theaction of the water and wind power. With the distance to the gangue field became father, thecontent of heavy metal became lower, gradually became normal levels. (3)The results of the geoaccumulation index showed that the pollution of heavy metalwas serious in the gangue field. The pollution of Cd was the moderate or lay particular stressdegrees on the level of pollution, the pollution of Ni, Zn and Cu was mild, the pollution of Crand Pb was negligible. The pollution degree of heavy metal was that Cd＞Ni＞Zn＞Cu＞Cr＞Pb. In the gangue field surrounding areas, the pollution of Cd was severer, it was defined asmoderate or partial moderate degrees in the geoaccumulation index, the pollution of Ni, Zn,Cu and Cr was mild or negligible, Pb was no pollution. Cd, Ni, Zn, Cu, Cr and Pb had basicreached no pollution levels in the areas over250m away from the gangue field, but thepollution of Cd was still mild in the downsteam channel over600m away from the eastgangue field.(4) The results of the potential ecological risk index showed that, using evaluation of thesingle metal potential ecological risk index, Cd was severe or extremely severe potentialecological danger level. Ni, Zn, Cu, Cr and Pb were mild potential ecological danger level inthe gangue field, There were the same station in the surrounding areas of the gangue field.Using evaluation of multiple metal potential ecological risk index, in the gangue field, thefirst and second sample plot with short years of discharging gangue were lay particular stresspotential ecological danger level, the third, fourth and fifth sample plot with relative longeryears of discharging gangue were moderate potential ecological danger level.The east, westand north parts in the surrounding areas of the gangue field were moderate potentialecological danger level, the south of it was mild potential ecological danger level. |
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