The Management And Risk Assessment Of Soil Pollution In Uranium Tailing District

The nuclear industry is an important cornerstone of national security,and uranium is called the"food"for the nuclear industry.With the increasing demand for uranium in China's nuclear industry,it becomes inevitable to produce a large amount of uranium waste rock and uranium tailings in the process of mining and smelting uranium.These uranium waste and uranium tailings as a big stock will occupy a large area with radioactivity,and give off major heavy metals and organic compound pollutants,which would endanger the surrounding atmosphere,soil and water environment with health risk.It has aroused a wide concern that soil investigation and risk assessment should be carried out in uranium tailings areas during the protection of land sources.It is still be a great challenges that to complete the soil evaluation and management due to the complexity and particularity of components of uranium waste rock and uranium tailings.Furthermore,it is also a major system engineering involving basic science and management issues.Therefore,this study has important theoretical and guiding significance,which can provide reference for soil protection,utilization and management of uranium tailings mine.In this work,we took a large tail of uranium mine in our country as the research object,and used a series of methods such as scene reconnaissance,investigation and analysis,sample collection,also the multi-disciplinary(the environment,biology and management etc.)cross theories are applied in the analysis of pollution factors and evaluation index system in the contaminated soil of uranium tailing area.The model of soil risk assessment with microorganism as index was established,and the control countermeasures of soil pollution in uranium tailing area were put forward.The main results are as follows:(1)Based on the tail of uranium mining area contaminated soil samples and test analysis,using material field research method,we determined the research of regional soil nuclides and the basic characteristics of microbial community,and discovered the 49 microorganisms door,102 classes,197 microbes.It is concluded that the Firmicutes,Proteobacteria,Actinobacteria,Bacteroidetes its content accounted for more than 75%of the total soil microorganisms.(2)Based on the change of soil microbial growth,metabolism,development process and the stability studies,we found that microbial flora as dominant species are not disappear during uranium mining activities,which indicate the microbial characteristics in soil are related to uranium mining area pollution soil environmental risk.It is concluded that the stability of soil microbial indicators can be used as a soil environmental risk assessment,also can be used as the pollution index in the tail of uranium mining area.(3)By studying the distribution characteristics of nuclides(U,Ra)in soil,there is a significant polynomial change relationship with soil microbial diversity,microbial biomass,basic respiration rate,metabolic entropy and microbial activity.It is found that extremely significant correlations among soil microbial diversity,microbial biomass carbon(Cmic),microbial biomass nitrogen(Nmic),basal respiration rate and metabolic entropy.The model of the microbial risk assessment for the soil environmental pollution is established by using index data standardization and principal component analysis,which based on the microbial biomass and diversity.(4)Referring to the experience of foreign uranium tailings management practices,we proposed the bioremediation measures of contaminated soil in uranium tailings area and related management countermeasures in our country.It is believed that the management of uranium tailings area should speed up the construction of legislation,improve relevant systems and standards,break the current situation of multi-management management,refine the functions of various departments;establish and improve the protection of diversified restoration funds and third-party governance mechanisms;strengthen the risk monitoring and control of uranium tailings areas.Besides,we also should improve database and file management;introduce microbial evaluation indicators,improve the uranium tailings soil risk assessment system;formulate a complete emergency management mechanism,make emergency response plans;promote the disclosure of environmental information in uranium tailings.The policy also should ensure the public's right to know,and promote the public Participate in the environmental management of the uranium tailings area to ensure long-term effective supervision of environmental safety and public health.