A Study On The Relationship Between The Surface Soil-plant-microbe Interaction And The Optimized Model Of Vegetation Restoration In The Lead-Zinc Mine Tail Reservoir Area Of West Sichuan Dry-hot Valley

Mining ecological problems are one of the hot issues of global attention,and the accumulation of tailings ponds will aggravate the ecological and environmental problems.Vegetation restoration is the most effective and sustainable method to conduct mine environmental pollution control and restoration of degraded ecosystems.Indigenous plants are the best choice for phytoremediation in mine environment.To understand the remediation ability of indigenous plants in mining areas and the soil interaction is importance of guiding significance for ecological restoration in mines.Aiming at the issue of vegetation restoration and ecological reconstruction in the lead-zinc tailings reservoir area based on dry and hot valley climate conditions,this thesis compared and analyzed the surface soil quality,the diversity of plant and microbial in different vegetation restoration stages using field investigation and experimental analysis,at Tangjia lead-zinc tailings reservoir area in Hanyuan county,west Sichuan dry and hot valley research area.We also evaluated the quality of surface soil environment in this tailings reservoir area,and studied on the response relationship between the physical and chemical properties of soil,heavy metal content and plant communities and microorganisms in different vegetation restoration stages.This response relationship also reveals the change law of soil-plant-microbial diversity in the process of vegetation restoration.This thesis also proposeds an optimized model of vegetation restoration and ecological reconstruction in the current situation of the tailings reservoir area,with a view to the subsequent vegetation restoration process of the tailings reservoir area.Artificial beneficial intervention provides scientific basis and repair countermeasures.The paper mainly achieved the following results:(1)Based on the detection and analysis of the heavy metal content of the soil in the tailing reservoir of Tangjia lead-zinc mine in Hanyuan,the results show that the contents of Pb,Zn,Cd,As and Cu in the surface soil exceed 140.74 times and 34.91 times,288.35 times,22.39 times,1.13 times,than that of Sichuan soil background values,We utilized single-factor pollution index method,Nemero comprehensive pollution index method and potential ecological risk index to evaluate the heavy metals in the tailings reservoir soil,the results show that: Pb,Zn,Cd,As have achieved heavy pollution,and there is no Cu pollution,and high ecological risk of heavy metal pollution in the tailings reservoir area.(2)The investigation of plant community diversity in study area was found that plant diversity was negatively correlated with heavy metal content and positively correlated with soil physical and chemical indicators.With the restoration of vegetation,the heavy metal content in soil was gradually decreased and soil fertility was gradually improved.The plants in the tailings reservoir area and surrounding areas have good absorption capacity for Pb,Zn and As.Five repair potential species of plants,such as Eriophorum comosum,Phragmites australis.,Leptodermis pilosa Diels,Incarvillea argute,and Podocarpium podocarpum,were selected.(3)Analysis of soil microbial communities in the tailings reservoir area of Tangjia lead-zinc mine in Hanyuan is conducted by high-throughput sequencing.The results showed that: Proteobacteria,Actinobacteria,Chloroflexi and Acidobacteria are predominant flora;the Ascomycota,Basidiomycota and Calcarisporiellomycota are predominant flora in the fungal community.The diversity of plant community and the physicochemical factors of soil have a larger impact on microbial composition.The three heavy metals Pb,Zn and Cd have a greater correlation and higher impact on microbial community diversity.Gaiella,Sulfurirhabdus,JG30-KF-CM45 in the bacterial domain and Neoascochyta and Cutaneotrichosporon in the fungal domain are well tolerant to heavy metal stress,and can be used as the next step for screening resistant strains.(4)According to the natural restoration situation of the Tangjia lead-zinc tailings reservoir area,based on plant community investigation,dominant plant selection,microbial community analysis,dominant plants of herbs,shrubs,and trees were screened out in four stages for vegetation restoration,the early two species of Eriophorum comosum and Phragmites australis are pioneer plants,inoculated with microbial predominant flora at the same time;in the middle and early stages,adding herbs(Pteris fern,Kidney fern)and shrubs(Huzhizi,Chuandianye lilac,Masson)is to,increase plant species with mix high and low plant;adding herbs(two-headed hair,long-leaved locust locust),shrubs(Hangzi shoots)and trees(Dendrobium spinosa,vitex)is another method in the middle period and to introduce super-rich plants for restoration in late period.