Available Contents And Affecting Factors Of Heavy Metals In Different Types Of Reclaimed Lands In Coal Waste Pile

Coal waste pile stacking not only occupies land resources,but also brings many ecological and environmental problems,so,It is an urgent task to improve the ecological environment of the mining area by reclaiming the coal and gangue mountain.The vegetation reclamation after leveling the soil is an important measure for the treatment of the coal and gangue mountain,but the reconstruction soil after pushing and covering the soil disrupts the original soil structure.The physical and chemical properties of the soil become worse and affected by the migration and transformation of heavy metal elements in the coal gangue,which may lead to the pollution of the reconstructed soil,which is an important limiting factor for vegetation restoration in the coal gangue mountain.Therefore,the physical and chemical properties of soil,heavy metal pollution and the main factors affecting the content of effective state of heavy metals in different land use types are identified.It is helpful to guide the reclamation of the Coal Gangue Mountain "according to local conditions",and at the same time,it can provide reference for the scientific utilization of the reclaimed land of the Coal Gangue Mountain.The reclaimed 8 years’ farmland,orchard and retrogress wasteland in Cao Village of Huozhou City in Shanxi Province are taken as subjects.analyzed the 0-40 cm soil layer 3reclamation soil physicochemical properties,the cumulative evaluation status and pollution of heavy metals,mainly affects the available content and the bioavailability and bioavailability of heavy metal content factors.The main results are as follows:(1)According to the soil physical and chemical properties of three reclaimed plots(0-40cm):The organic matter,cation exchange,clay content and powder content in FL sample plots were significantly higher than that in OL and GL samples;The pH and sand content of OL samples were significantly higher than that of FL and GL samples.The conductivity of GLsample was significantly higher than that of FL and OL like land;Compared with CK,except for pH value and cation exchange capacity,pH value,electrical conductivity,clay content and particle content were all larger than those of CK plots,while organic matter and sand content were all less than those of CK plots.(2)According to the total amount of heavy metals and pollution evaluation of three land use types,the contents of heavy metals in the three reclaimed land samples showed that the Pb content of FL sample land in 0-20 cm soil layer was significantly higher than that in OL and GL plots.But the content of Ni was lower than that of OL and GL,and the content of Ni in the soil layer of 20-40 cm was higher than that of FL and GL.Compared with CK,the content of As、Cu、Cd、Hg in 0-20 cm soil layer was higher than that of CK,and it was higher in20-40 cm soil layer.The content of heavy metals in 20-40 cm soil layer was higher than that in CK plot except Pb、Ni.The results showed that the pollution index of heavy metals was evaluated by single factor pollution index.The evaluation results of Nemero comprehensive pollution index and potential ecological hazard pollution index showed that,The assessment of single factor pollution index showed that the accumulation of Pb、Cu in FL land was more significant than that in OL sample land,the accumulation of As in OL samples was more significant.The accumulation of Pb、As、Cd and Hg in GL samples had a certain accumulation,and Hg belonged to severe accumulation,and Cd was moderate accumulation.Compared with CK plot,except that the Pb and Ni elements are lower than the CK sample,the other elements are higher than those of the CK sample.the accumulation of Pb、Ni was higher than that of CK plot.Elements were lower than CK plots and the other elements were higher than CK plots.The comprehensive pollution index evaluation of Nemero showed that the comprehensive pollution degree of heavy metals in the soil of three reclaimed plots and CK plots had reached heavy accumulation,the Nemerow comprehensive pollution index in descending order of GL、FL、OL and CK plots.The evaluation of potential ecological hazards is basically consistent with the evaluation results of single factor pollution index and Nemero’s comprehensive pollution index.(3)From the content of active state and bioavailability of heavy metals:The content of effective state of heavy metals showed that the content of Pb 、 Cu and Hg in FL and GLsamples was higher in 0-20 cm soil layer,and higher than that of OL and CK like land.In the20-40 cm soil layer,the content of Pb、Cu and Hg in GL samples was significantly higher than that in FL and OL samples,and was significantly higher than that in CK like land.The bioavailability of heavy metals showed that in 0-20 cm soil layer,the bioavailability coefficients of Pb、Cu and Hg in GL plots were all higher than those in FL and OL plots,and Hg bioavailability coefficients in FL plots were higher than those in OL and GL plots.In the20-40 cm soil layer,the other bioavailability coefficients were significantly higher than that of FL and OL like sites,except for Pb in GL samples.In the 0-20 cm soil layer,the bioavailability coefficients of Hg in GL and FL plots were higher than those in CK plots.In the soil layer of20-40 cm,the bioavailability coefficients of the three reclaimed plots except Cu were lower than those of CK plots.(4)The effect on content of available heavy metals from 3 kinds of physicochemical properties:pH、heavy metal content and electrical conductivity are the main factors affecting the content of Pb and Hg.Soil cation exchange,organic matter and pH value are the main factors affecting the content of Cu.The pH is negatively correlated with Pb,Hg and Cu available content.The total amount and conductivity of heavy metals are highly positively correlated with the effective content of Pb and Hg.The exchange rate of organic matter and cation has a significant positive correlation with Cu effective state.