Research On Pollution State Of Heavy Metal To The Soil Of Mining Area In Hubei Province

Minerals buried in earth are exposed on the surface environment with exploitation and metallurgy of mines, which greatly changes the original structure and state of soil environment. Heavy metal elements enter into surrounding environment with wastewater irrigation, atmospheric dust, tail slag dust or leaching water in mining activities, and when their contents are beyond purification ability of soil, heavy metal pollution will take place in soil. Heavy metal pollution in soil will not only make damage to ecological environment and human health, but also become impediment for development of mining industry. Therefore, research on heavy metal pollution in soil of mining area has become increasingly prominent, while ecological restoration and remediation of environment pollution are more and more urgent in mining area.The thesis took a certain mine of Hubei province as a key research object, with soil samples collected systematically according to different functional areas of the mine and heavy metal content measured by atomic absorption spectrophotometer and other equipment indoor, and heavy metal pollution characteristics and pollution rules of soil samples in the mining area were analyzed on this basis. Analysis and evaluation on the degree of heavy metal pollution were made by using the nemero index method, geo accumulation index method, fuzzy comprehensive evaluation method, while potential ecological risk index method was used to evaluate the ecological risk of the mining area.Results showed that average contents of Cu, Zn, Pb, Cd and Ni in mining area soil were higher than that of background value of Hubei Province, and average content of Cd exceeded background value of 79 times. Contents of Cu, Zn, Pb, Cd and Ni were significantly increased in soil samples which were collected at downstream direction of sewage treatment station in the south of smelting area and tailings reservoir, and it indicated that smelting area and tailings reservoir made a large contribution to heavy metal contents of soil in mining area. Significant correlation of Cu, Zn, Pb, Cd was found, which revealed the four elements had same source of ore smelting process and tailings accumulation. There existed different extents of soil heavy metal pollution in industrial site, smelting area, tailings reservoir and office area, and transportation area of industrial site, downstream of sewage treatment station in smelting area and downstream of tailings reservoir were more serious area for the enrichment of heavy metals.Nemero index method showed that whether taking soil environmental background values of Hubei Province or the third level of national soil environmental quality standard as the evaluation criterion, 40 soil samples of a mining area in Hubei province had heavy pollution. Index of geo accumulation showed whether each point of single heavy metal element or average pollution index of all samples, Cd was always the highest, with the largest contribution to soil pollution. From results of fuzzy comprehensive evaluation, soil environment of mining area had been seriously polluted by heavy metals, which needed urgent settlement. Potential ecological risk assessment of heavy metals pollution indicated that Cd had a large potential risk to the ecological security of mining area, and ecological risk of the whole mining area was quite strong. Four evaluation methods comprehensively indicated that the mining area had been polluted by heavy metals, mainly by Cd, and comparatively more serious regions of heavy metal pollution were located at downstream of smelting area and tailings reservoir.