Speciation Of Uranium,Distribution Of Heavy Metals And Environmental Risk Assessment In Poyang Lake

Poyang Lake,as China’s largest freshwater lake,is an important over-water,dehydrated,seasonal shallow-water lake in the Yangtze River Basin,which has attracted the attention of government departments and researchers.In recent years,with the rapid development of local society and economy,the discharge of a large amount of industrial,agricultural wastewater and domestic sewage has made the environmental pollution of Poyang Lake area increasingly serious.Therefore,it is a very important research topic to learn more about the pollution degree of pollutants in the water body of Poyang Lake,study its pollution status,influencing factors,and the maximum bearing capacity of pollutants under certain environmental targets.In this study,the surface water samples and sediment samples of Poyang Lake were collected,and the content of different speciations of uranium elements in the water samples and sediments of each sampling point and the content of heavy metal Zn,Pb,and Hg pollutants in the surface water were determined.Based on this,the different speciations of uranium in the water of Poyang Lake and the content,distribution characteristics and pollution status of heavy metals in the surface water were explored.The single-factor pollution index method,Nemerow comprehensive index method and potential ecological hazard index method were used to control Poyang Lake.Evaluate surface water;use single factor pollution index method and geo-accumulation index method to evaluate the pollution status of different speciations of uranium in sediment;through correlation analysis,understand different speciations of uranium in water and Zn,Pb,Hg in surface water Correlation of heavy metal element content.Through this study,the macroscopic understanding of the pollution status of uranium and heavy metals in the waterbody of Poyang Lake is provided,which provides a reference for the environmental risk assessment in the waterbody of Poyang Lake and provides data support for the monitoring and treatment of radioactive and heavy metal elements.The main conclusions are as follows:(1)The average contents of suspended,exchangeable and stable states of uranium in surface water of Poyang Lake are 1.06,0.13 and 0.49 μg/L,respectively,and the average values are lower than the World Health Organization’s drinking uranium discharge standard values.The suspended state accounts for 61.5%,the spatial difference is the largest,the distribution is uneven,and the distribution trend is increased first and then decreased from north to south.Most of the southeastern part of Poyang Lake and the northern part are more exchangeable.The high part;the Yangtze River has a greater impact on the spatial distribution pattern of the steady state.The Poyang Lake is basically a non-polluted area,with some areas being slightly polluted,and the suspended state is the main pollution contribution form.The potential ecological risk assessment of uranium in the surface sediments of water bodies is moderately polluted.(2)The average contents of exchangeable,carbonate-bound,iron-manganese oxide-bound,organic-bound,and residue lattice-bound states of uranium in the sediments of Poyang Lake are 0.056,0.081,0.509,0.286,0.668 mg/kg,respectively.Neither exceeds its background value.The difference in the spatial distribution of carbonate-bonded states is the largest,and the distribution is the most uneven.From north to south,the distribution trend decreases first,then rises,and then decreases;the organic-bonded states are followed,and the northern part of Poyang Lake is relatively high in total;the exchangeable states The higher values of Zn occur in the northern estuary region and the southern region;the spatial distribution pattern of the latticebound state of the residue is similar to the iron-manganese oxide bound state,showing a higher phenomenon in the southeast of Poyang Lake.The sediment of the entire Poyang Lake area is not polluted by uranium and is at an unpolluted level.(3)The average contents of Zn,Pb and Hg in surface water of Poyang Lake are17.9,14.0,0.0334 μg/L,respectively.The content of Zn at all sampling points is lower than the standard of surface water environmental quality,and the average content of Pb.The maximum value is higher than the standard of one class,and the maximum content of Hg is much higher than the three types of standards.The spatial distribution characteristics of Zn are less obvious,with lower values in the southern and northern parts of Poyang Lake,and high values at individual sampling points;Pb is generally larger in the northern spatial distribution pattern than in the south;Hg content is highest in the Raohekou region in the southeastern part of Poyang Lake.A certain diffusion trend is presented.The surface water Zn is a non-polluted area in the whole Poyang Lake.Pb is mostly a slightly polluted area,and Hg is slightly polluted in the upper reaches of the Rao River,but it is within the controllable range.Pb and Hg are major pollution contributing elements.The correlation analysis between heavy metals and uranium shows that the Zn content is significantly positively correlated with the suspended uranium content in the surface water and the exchangeable and residual lattice combined uranium content in the sediment;Pb and Hg content are more correlated with uranium content weak.