Analysis And Prediction Of Heavy Metal Migration Time Effect Of Sea Buckthorn Remediation Tailings Dam

Tailings pond is a major source of danger and pollution in mines.The diffusion of heavy metal pollutants in tailings ponds will pollute the surrounding soil and water environment,and bring a series of ecological and environmental hazards.Ecological remediation is an effective measure to treat heavy metal pollution in soil of tailings pond.At present,there are few studies on the time effect of vertical migration of heavy metals in soil-plants of ecological restoration tailings dam.and there are also few studies on the longitudinal migration of heavy metals in soil.In this paper,the slope structure of the study area of tailings dam is modeled.The Geostudio software is used to simulate the rainfall infiltration in the study area of tailings dam.Therefore,the longitudinal migration range of morphologic heavy metals in the phytoremediation tailings dam can be determined.According to the simulation results and the field conditions,the sea-buckthorn and the repaired layered soil in the 3,7,13 and 17 years of tailings dam restoration were collected.The physical and chemical properties of soil samples,plant growth indexes and the content of morphologic heavy metals were detected.From two aspects,the time effect of longitudinal migration of morphologic heavy metals in tailings dam and the ability of sea-buckthorn to enrich and transport heavy metals,the time effects of heavy metal migration in the tailings dam of sea-buckthorn remediation were analyzed.Then the grey prediction model of heavy metal content in tailings dam is established and predicted.The research results provide a theoretical basis for the study of heavy metal pollution control in mines.The main results of this paper are as follows:(1)The rainfall depth of the tailings dam was obtained by using Geostudio software.The longitudinal restoration range of heavy metals in tailings dam by seabuckthorn for 3,7,13 and 19 years are confirmed,which are 0?1.2m,0?1.2m,0?1.4m,0?1.5m,respectively.It provides theoretical basis for field sampling analysis.(2)With the increase of time of sea-buckthorn remediation of heavy metals in tailings dam,the tailings soil changes gradually from alkaline to neutral.With the increase of organic matter content,soil quality was gradually improved.The increase of redox potential enhances the oxidation of heavy metals in the tailings soil.(3)The content of available Cu and Zn in tailings dam can be continuously absorbed by sea-buckthorn is very low,which mainly exists in the form of residue.The content of available Pb which could be continuously absorbed by sea-buckthorn was high,and the available forms,such as humic acid and iron and manganese,were gradually transformed into plant absorbable forms.(4)The content of Pb in sea-buckthorn was higher than that of Zn and that of Cu.With the increase of time,the enrichment and transport capacity of Pb of seabuckthorn is gradually increased,the enrichment and transport capacity of Zn and Cu is decreased,and the increase of time is gradually decreased.(5)The established grey prediction system meets the requirement of prediction accuracy.The grey prediction model was used to predict the restoration of the 19-year slope surface.The results show that after five years,ten years and 15 years,the contents of ion-exchanged and humic acid-bound Pb in tailings soil decrease with the increase of remediation time,and the longitudinal distribution is relatively uniform.The content of carbonate-bound Pb and strongly organically-bound Pb increased with the increase of remediation time.The distribution of carbonate bound Pb is relatively uniform in the vertical direction,and the content of strong organic-bound Pb decreases with the increase of depth,which shows the law of migration to the surface.The Fe-Mn combined state Pb in the tailings soil with 0?20cm and 80?120cm increased with the increase of the remediation time.The Pb content of Fe-Mn combined state in the 20?80cm tailings soil decreases with the increase of remediation time,increases with the increase of depth,and the deposition occurs in the deep layer.