| Anshan city, the"steel capital", is the largest iron and steel industrial base and plays an extremely important role in China's national economic development. As the most important iron producing base, Anshan iron ore has been explored for more than 80 years, which causing some inevitable impacts on the ecological environment. For example, the occupied and damaged mining pits; the stripped topsoil, which is causing vegetation damage and soil erosion; undermined balance of the stratum during the mining and engineer building. Thus, it is so closely related between the mining city's development and the mine reclamation that the mining ecological restoration of Anshan is imperative for a continuable development strategy. Whether the disused mining land can be restored to the original ecosystem or can be rebuilded a new harmony ecosystem has been focused by many scholars in recent years. In this paper, the different lands of Dagushan disused mining area and Qidashan disused mining area are selected for the research. A combination of soil science, geochemistry, ecology and other related theories can be used, field surveys and indoor test and analysis are the research method to study the geochemical characteristics of the soil, plant communities, and animal communities and so on, and the following are the research achievements:Through the normal examination, the test results of soil heavy metals are compared with the national background value and the background value of Liaoning Province, only the content of Hg and Cd are higher than background values in the first samples, the content of Zn, Cu, Co, Pb, Cd of soil are much higher than the background value in the second samples. Compared with the first sample, In the second samples of soil, the average content of Zn, Mo, Pb shows a clear upward trend while the content of Hg declinling obviously. Through the correlation analysis of heavy metals in the soil, Zn, Cu is the most contaminated elements accompanied by the pollution while a much smaller correlation to Hg, Mo and other heavy metals .For the constant element in the soil, with the increasing reclamation of years, the content of the total carbon and the total nitrogen in soil increase. Despite the increase in the content of P, but it still stay in a lower level compared to the background value of the country, and there is a relative lack of phosphorus in soil over the district of iron ore reclamation; The contents of K2O, MgO, Mn, Fe2O3, CaO, and Al2O3 have showed different degrees of increase, and the content of Na2O, SiO2 decline. Ti element is more stable and changes little. For the soil trace elements, with the increasing reclamation fixed numbers of years ,the contents of B, V, Hg, Cr decrease; The difference of Ni, Cd, As elements is so small that there is almost no change;The contents of Zn, Cu, Mo, Co, Se, Pb element increase.2. In order to study the geochemistry characteristic of rare-earth element of abandoned mines,in this paper, combined with statistical analysis and comparative analysis, studies the characteristics of total REE and standardized characteristics comprehensively. The results show that the total REE of reclamation mine is greater than the background value of the country. The group correlation of LREE and HREE is superior to the inter-group correlation. The REE content of research area is strictly obeyed to Oddo– Harlins rule. The content of LREE and HREE in the research area is great different, and where LREE enrichment,δEu andδCe weakly loss. The content of the second samples in line with chondrites distribution more than the first samples. Compare with the relevant background value, the second samples'distribution characteristics of REE content closer to the background value.3. Soil physical and chemical characteristics are important aspects of the soil reconstruction study, the results of soil physical and chemical characteristics'test show: Compared with the first batch of samples, pH of the second batch of samples is higher only by 0.23, the soil moisture content of the second batch increases in some degree, soil organic carbon average and soil proportion of the second patch decline in some degree. The correlative study on soil physical and chemical characteristics, soil constant and trace elements shows that soil pH is positively correlated with the contents of As, Al2O3 and Mn but it is negatively correlated with the contents of C, N, Se.4. Through the normal distribution test, correlation analysis and other statistical analysis, the paper makes a systematic research and analysis to the geochemical characteristics of heavy metals in the study area. The paper makes heavy metal pollution evaluation for the study area of two samples using the Pollution degree evaluation, Igeo and Potential ecological risk index three methods; through the comparison of the two evaluation results, research results show that, compared to the first sample, there is a degree of deterioration to the soil heavy metal pollution in the study area when the second sample was took. Only a portion of heavy metal elements (Ni, Hg, Cr, As) content and evaluation results appear improving. So we should make adequate attention to this phenomenon.The gray correlation degree method was applicated to evaluate the environmental quality of soil. And the results show that the environmental quality of soil only reach the soil threshold for the protection of agriculture and forestry production and normal growth of plants.5. As the reclamation time increases, tree height, diameter, basal area, canopy cover and timber stock grow more quickly. The survey of herb layer plants shows that the biotopes of studying area are appropriate for the growth and propagation of Setaria and the Setaria affects the biotopes a lot at the same time. Because Setaria's aerial part grows well, mesa 1, mesa 3, mesa 4, mesa 5, mesa 6 of Dagu mountain original vegetation community form the background, but mesa 2 doesn't form the background although Setaria grows well here. Moreover, for sample 2 of mesa 6, ragweed's aerial part can't form the background. Apart from this, the vegetation, such as Mongolica, northeast Artemisia capillaries, Oxtongue, Cassia nomame ect., grows well.6. In the process of renewing the disused mining ecological system, soil animals are indispensable part of the ecosystem, and are one of the biological indicators of a stable ecological system, and can be used as biological indicators of environment monitoring and evaluation. After continuous investigation of Dagushan abandoned land, we find, in the different stages of the five sections, the large soil animals were attached to 11 categories, 4 programs in 2 phylums, and there are 2 predominant groups, 1 common group, and 9 rare groups. This shows that the soil animals'structure in Dagushan abandoned iron field is simple, and the composition of the community is the wide-spread species, In the 8 different manual forests of Daqishan iron disused land, there are 13 categories, 10 projects, 4 programs and 1 phylum. The dominant groups are Formicidae, Coleoptera (including larvae), the Centipede, and Araneid(four categories), the common groups are Hemiptera, Lepidoptera (including larvae), Diptera, Hymenoptera, Isoptera, Chilopoda, Chilopoda, Orthoptera, the rare groups are Orthoptera, Symphyla. The total component individuals in dominant groups and common groups are 99%, which constitute the principal part of the soil fauna. It reflects that the soil fauna system is still at its preliminary stage, and their ecosystem adaptability is weak. |
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