| The river is the main way to carry the surface material.The material composition of the material is closely related to the geological environment,the rock component and the geochemical background.River sediments not only reflect the characteristics of the current depositional environment,but also preserve the history of the evolution of the river environment.In the century scale,the phased development of mining activities is one of the important factors affecting the environmental quality of river sediments.Mianning Rare Earth Mine is a concentrated area of mining activities,and its stage development characteristics are prominent.The influence of mine mining on the environment is mainly through the water system,which can find out the geochemical characteristics and migration and transformation of different media elements in the water system,which is very important to the treatment of mine environment and the planning of downstream land use.Based on the spatial distribution characteristics of different media(overlying water,sediment,interstitial water)elements in the mine water system,the paper analyzes the spatial distribution of the elements in the sediments of the sediments in the mining area,based on the investigation of the ecological and geochemical survey of lakes and mines in Anning River Basin,Sichuan Province.Characteristics and morphological characteristics of the sediments were investigated.The migration rules and influencing factors of the elements in different media were discussed,and the environmental quality of the sediments was evaluated.Research shows:(1)The pH of overlying water in two rivers is between 7.45-8.13,which is weak alkaline water and weakly reducing environment.The heavy metals Cd,Pb,Zn and Mn in the sediments of the Nanhe River have similar changes in the peak characteristics,which characterize the same material source,and Pb,Zn and U show strong enrichment.(2)Most of the elements in the three phases in the order of order: sediment> interstitial water> overlying water.Overlying water suspended solids in the precipitation process to absorb a large number of heavy metal elements,which purify the overlying water quality.However,it also causes the deposition of environmental pollution.Mining of rare earth minerals is the main factor causing the pollution of the South River sediments.(3)The morphological studies showed that the order of element migration in sediments was Pb> Cd> Zn> U> Cr> As.The content of heavy metals and nuclides U in the sediments of the Nanhe River affected by the mining area is higher than that of the Anning River,and the elements are active and have strong migration ability.The migration ability of Cr,U and Pb in the sediments of the sediments is increased from the surface to the bottom.The migration ability of Cr,U and Pb in the sediments of the sediments is reduced from the surface to the bottom.(4)The migration ability of the remaining elements in the sediments of the study area is positively correlated with the pH of the interstitial water,but the correlation is weak,and it is negatively correlated with the conductivity of the gap water and positively correlated with the Eh of the interstitial water.(5)The sediments and sediments of the Nanhe sediments are polluted by Cd,Pb and Zn,and the pollution degree is from strong to strong.The degree of pollution of Pb in the sedimentation tank is medium-strong,and the tendency to enhance the pollution degree with depth is strengthened.The degree of Pb pollution is strong-strong,the pollution degree of Zn is no-strong,and the deep pollution degree on the surface.Anning River upstream sampling point is not contaminated.The sedimentary environment of Nanhe River is a moderate ecological hazard,and the sedimentary environment of Anning River is a slight potential ecological hazard,and the sedimentary environment of sedimentation pool is a strong potential ecological hazard. |
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