Evaluation Of Heavy Metal Contaminated Soil And The Effect Of Leguminous Plants Remediation In Typical Mining Wasteland In Jilin Province

With the development of social economy, environmental pollution and eologicaldamage was becoming increasingly prominent. In recent years, coal mineconsolidation efforts were increased in Jilin province because of coal minedevelopment. However, a large number of farmland area was contaminated by heavymetal becoming abandoned due to lack of necessary environmental restorationmeasures. This caused serious impact on the sustainable development of Jilinprovince economy. Therefore, it is very important to carry out evaluation of heavymetal contaminated soil and take measures of ecological remediation in miningwasteland.In this paper, on the basis of the data collection and field investigation, threeleguminous plants were chosen to research the abandoned soil fertility and degree ofheavy metal pollution, whose name are the Melilotus suaveolens，Medicago sativa L.and Trifolium repens L. According to analysis the soil feature, physical and chemicalproperties of plant nutrition organs, heavy metal elements were explored in soil anddifferent organs. Certain methods were selected to study ecological landscapereconstruction and planning design in the study area land. The main conclusions areas follows:(1) Integrated fertility index of reclaimed soil belongs to level Ⅲ, moderate soilfertility, but cadmium pollution is very seriously. While, fertility of gangue soil inlevel Ⅳ, with the barren soil, soil organic matter, hydrolysable N, rapidly available Kand available P was very low, the pollution of heavy metal cadmium is extremelystrong.(2) Fertility composite index has significantly improved in both two soils afterplanting three kinds of legumes, soil heavy metal pollution has reduced. Theimprovement by using Medicago sativa L. is best in Reclaimed soil, Pollutionintensity dropped to moderately polluted. The improvement by using Melilotussuaveolens is best in gangue soil, while pollution intensity dropped to slightly polluted.Integrated fertility index continuously improved by extending planting time, while,the degree of pollution is on the contrary. With the extension of planting time, heavymetals was from soil to plants gradually in the soil-plant, Melilotus suaveolens andMedicago sativa L.will be adviced as restoration grass seed of the sdudy area,in order to achieve the best repair effect.(3) Transformation characteristics of heavy metal enrichment in organs weredifferent. For Melilotus suaveolens, the ability from high to low is leaf, root, stem inReclaimed soil, and it is stem, root and leaf in gangue soil. For Medicago sativa L.,the ability from high to low is leaf, root, stem in Reclaimed soil, and it is stem, leaf,root in gangue soil.(4) Enrichment of heavy metals in plants were different, the distributionregularity of same heavy metals are also different. For Melilotus suaveolens, rootmainly enriched Zn, Pb, Ni elements in reclaimed soil, none in gangue soil, stemmainly enriched Zn, Ni elements in reclaimed soil, Cu, Zn, Cd, Ni in gangue soil,leaves mainly enriched Cu, Pb, Cd elements in Reclaimed soil, Pb, Ni in gangue soil.For Medicago sativa L., root mainly enriched Cu, Zn elements in reclaimed soil, nonein gangue soil, stem mainly enriched Zn element in reclaimed soil, Cu, Zn, Pb, Cd, Niin gangue soil, leaves mainly enriched Cu, Pb, Cd, Ni elements in reclaimed soil, Cu,Zn, Pb, Cd, Ni in gangue soil.(5) Risk Analysis on accumulation of heavy metals （Zn、Pb、Cd、Cu、Ni）by vegetative organs like stems and leaves of two plants was taken, the result showsthat the single pollution index of five kinds of heavy metals was all less than1.0intwo years, heavy metal enrichment of stems does not exceed the amount of foragefood hygiene standards in both two plants, stems can be used as feed, Cd singlepollution index of five kinds of heavy metals in leaf is more than1.0two years, ithave been polluted seriously by heavy metals according to the forage food hygienestandards, so leaves can not be used as feed.(6) On the basis of soil fertility and comprehensive study on heavy metalpollution, screening for plant by combined livestock planning in the study area,determined the best repair mode, such as integrated model of ecological agricultureand ecological landscape mode combines. The ecological agriculture comprehensivemodel was given priority to with planting corn, Melilotus suaveolens, Medicagosativa L., thus forming a plant-farm as food chain comprehensive planting andbreeding base, the ecological landscape model in study area under the condition ofexisting environment is divided into three parts： First, Pinus sylvestrisvar.mongolica Litv., Populus alba var. pyramidalis Bunge, Amorpha fruticosaLinn.and Acer ginnala Maxim such as plant were planted for resisting wind, protecting water and soil. Second, Pinus tabuliformis Carrière， Populus alba’Berolinensis’ L.，Salix babylonica，Sambucus williamsii Hance，Sect. ChinensesDC.， Callistephus chiensis， Althaea rosea， Calendula officialis and Celosiacristata were planted in factory，for repairing heavy metal pollution at the same time.Third, because of the particularity of animal husbandry and land using, need to be setin its border protection barrier, in this study, Pinus tabuliformis Carrière,Salix babylonica and Rosa rugosa was used as a protective barrier main tree species,according to data, the three tree species, sterilization effect was good, and the tree isbigger, used in pastoral areas barrier effect is better.