Research On The Typical Heavy Metals Control In Situ And Biological Environment Improvement In Mercury Thallium Mine Waste

The mercury thallium mining area in Huilong Town,Xingren City,Southwest Guizhou Province has been stopped for many years,but the surrounding area is still plagued by various heavy metal pollution.A large number of exposed mercury,arsenic,antimony and thallium are continuously released into the surrounding environment under the influence of various biological or non-biological factors,causing serious pollution of mercury,arsenic,antimony and thallium,and increasing the health risks of surrounding residents.There are few reports on the in situ retention and habitat improvement of typical heavy metals in mercury thallium mine wastes with high toxicity,high pollution and high mobility.Therefore,this study takes a large number of mercury thallium wastes abandoned in Huilong Town,Xingren City,Southwest Guizhou Province as the research object.Based on the analysis of the pollution characteristics of mercury thallium wastes,according to the resource attributes of plant litter,aquaculture solid wastes and phosphate tailings.Select large grass herb macroflora litter(Pennisetum giganteum z.x.lin),high protein broad leaf deciduous tree litter(Broussonetia papyrifera),high nitrogen,high phosphorus and high biological activity of aquaculture solid wastes,and natural mineral phosphorus tailings with high calcium and high yield alkali activity as compound amendments and natural passivation agent,and macrophyta was planted to study the in situ retention and habitat improvement of typical heavy metals in mercury thallium mine wastes.To explore the effects of four natural amendments on the physicochemical properties of thallium mine wastes,respectively,alone and in combination,and the in situ habitat improvement of typical heavy metals(Hg,As,Sb,Tl)in mercury.The relevant research results can provide theoretical reference and technical support for the in situ control of typical heavy metals in mercury thallium wastes and the rapid ecological restoration of the yard environment,as well as theoretical basis and engineering practice experience for the resource disposal of aquaculture solid wastes and phosphate tailings.The main study results obtained are as follows:(1)The combination of amendments combined with plants can significantly improve the physical and chemical properties of the leach fluid in each experimental group and effectively control the dissolution of typical heavy metal pollutants.Compared with the control group,p H in each experimental group increased from acidic to weak alkaline,EC and Eh decreased to different degrees,and TOC content increased significantly;Tl and As(Stage 3 and 4)content in leachate decreased by 9.11%～100% and 2.32% ～ 91.87%,respectively;Sb content decreased in TSL group by 14.57%.(2)The combination of amendments combined with plants can improve the physical and chemical properties of thallium mine wastes.Compared with the CK group,the p H of the experimental groups increased to weakly alkaline,and the effective nitrogen,effective phosphorus,quick potassium and organic matter were2.58～25.43 times,2.06～7.85 times,4.73～13.25 times and 1.67～5.04 times that of the CK group,respectively.(3)Modifiers and combined phytoremediation enriched the microbial community in mercury thallium mine wastes.In each experimental group,Ace and Chao indexes were 2.49～4.19 times and 2.30～4.02 times that of CK group,respectively.Among them,TJGS group was TJGSL group,and Shannon index of TJGS group was 1.50 times that of CK group,and TJGSL group.(4)After the combined repair of amendments,the height,dry weight and chlorophyll increased in each experimental group.Compared with before planting,the TS group increased maximum 57.23 cm;the dry weight of TJGSL group increased maximum 49.08 g;except for TJ,TL and TG group,total chlorophyll was higher than T group;compared with T group,SOD activity in TL,TJG,TJGS and TJGS group increased,POD activity in TG,TL and TSL group increased and CAT activity was higher than that in T group.(5)Different enrichment of heavy metals in Pennisetum giganteum z.x.lin.In each experimental group,the enrichment of four typical heavy metals in mercury-thallium mine wastes by Pennisetum giganteum z.x.lin is shown as Tl>As>Sb>Hg.The highest content of Hg and As in TJ group was 48.23 μg/kg and1.32 mg/kg,respectively;the highest Sb content in TG group was 121.85 μg/kg;and the highest Tl content in TJGSL group was 6.22 mg/kg.