As the accumulation place of metals in the water environment, sediments can reflect the situation about how metals pollute waters. With the development of the three bases of coal mines, power plants and chemical factories in Huainan, lots of solid wastes were stacked on the ground surface. Because of the effect of weathering and leaching, hazardous metal elements among solid wastes will release and transfer into surrounding soils and surface waters, snd they will damage the ecological environment of the mining area. Through studying on the surface sediment of subsidence-waters in the mine area and waters around the ash field, this paper analyzes the characteristics of metal distribution and enrichment by measuring the total amount, and reveals the situation of water pollution by metals under the influence of the development of coal mines and power plants through the scientific evaluation, predicts the ecological risk on the water quality caused by metals, meanwhile, studies the mobility law of metal elements. The results show that:1,According to the sediments of subsidence waters in the mining areas, the damage degree of Cd is larger than other metal elements'. The order of degrees in which the ecology is harmed in the study area is, abandoned mining areas' > old mining areas' > new mining areas'. The longer the time of the exploitation is, the higher the degree of weathering and leaching of coal gangue rises, and the more serious the potential ecological risk caused by metals becomes in the mining area.2,Through the assays of waters sediments in the three major ash fields in Huainan, the damage from Cd is the most serious. The order of harm-to-ecology degrees of the study areas is Shangyao sampling area's > Gaohuang sampling area's > Xinji sampling area's. The morphology of metals in the coal fly ash is mainly the residual state and the amount of metals in the coal fly ash transferring to the environment is very small. However, as the stacking time passes, the proportion of soluble stated metals in the coal fly ash will get bigger and bigger. pH obviously influences the morphological concentration of Cd in soils surrounding the ash field, it is an important factor for Cd to enrich in sedimentary environment.3,The concentration of Cu in the overlying level of subsidence waters in Tianji exceeds the corresponding one of environmental quality standards for fishery water , the concentration of Hg exceeds the corresponding one of environmental quality standards for surface water . The concentration of Cu and Zn in the superficial sediment is relatively higher. Through the analysis of metal correlation, it is found that As, Cr and Cu in the superficial sediment maybe come from the same pollution source, and Hg, Pb, Cd and Zn maybe also get out of the same pollution source. The morphology of metals in the superficial sediment of project area is mainly the residual state, the possibility of a secondary water pollution caused by metals is smaller.It is found that the damage caused by Cd is the most serious by evaluation. Under the brush of wind and rain lots of particles drop off the coal gangue and the coal and cover on the soil near the mining area, which causes that the metals concentrations in soils of the coal mining subsidence land of the project are a little higher than those in soils of the ash field of Tianji power plant.Through the investigation on metal pollution of water environment, it is found that the ecological risk of sedimentary environment of the all subsidence waters and waters around the ash field is of a slight and safe grade. |