Monitoring And Evaluation Of Radioactive And Heavy Metal Pollution Of Surface Water And Surface Sediments Around A Uranium Mine In Northern Guangdong

Waste water from the process of uranium mining,ore crushing and rain leaching of the barren rock generally contain radioactive elements(U,Th)and other heavy metal elements.The wastewater flow into the surface water surrounding the uranium mining area,may cause water environment pollution.As the oldest brand uranium mine of the nuclear industry,the mine in Southern China has made a great contribution to the development of China's nuclear industry,in the same time,mining activities also have an impact on the surrounding surface water environment.In this paper,take the two surface water surrounding the uranium mine as the research object,the No? wate is located the upstream of the mining area and far from the pollutant sources,the main pollutants flow into the No II water.Twenty-one surface water and surface sediments samples were collected according to sampling point set layout principle of the EIA guidelines.The water samples were measured by Inductively Coupled Plasma Mass Spectrometry(ICP-MS),while the surface sediments samples were measured by Atomic Absorption Spectrometer(AAS)for the concentrations of radioactive and heavy metal.A variety of evaluation methods were used to evaluate water environment quality.At the same time,analyzed and identified the Ostracoda species in the surface sediments,using the sensitive species to indicate the water environment of the mining area.The main achievements are as followings:1)The radioactive elements(U,Th)and related heavy metal elements(Cr,Co,Ni,Pb,etc.)in the surface water of 21 sampling sites in the mining area were tested and analyzed,and the surface water pollution was evaluated by the Nemero index method.The results show that: The Excessive elements of surface water surrounding the mining area were U,Tl,Pb,As.The content of U in waste rock yards and small hydropower station was higher than other sites.According to the evaluation results,the ? was more serious than the ?,but generally the pollution condition of thesurface water is still in the acceptable range.The main pollution sources of uranium mining were the waste water from mining,crushing rocks and waste rock yards,additionally wastewater from farmlands and pig farms was also not to be neglected.2)The contents of U and related heavy metals in the surface sediments surrounding the mine were tested,analyzed by the principal component analysis,and the surface water pollution was evaluated by the Geoaccumulation index and potential ecological risk index,the results show that: the contents of U,Cu,Pb,Cd,Zn and Mn exceeded the background value of soil,the average content of Cd exceeded the background value of soils in Guangdong province nearly 50 times,the average content of U exceeded the China soil background value about 10 times.Analyzed all the heavy metal elements,in the first principal component F1 Cd is the highest load elements,Cd was significantly enriched and the sediments were polluted;in the second principal component F2,U is higher,which mainly related to soil erosion,rock weathering,mining and other relevant reasons;the Index of Geo accumulation showed that the surface sediments was polluted by heavy metal of Cd,U,Pb,Mn,Cu,Zn,pollution degree from big to small in proper order were: Cd > U > Pb > Mn >Cu > Zn;Potential Ecological Risk Index showed that the pollution degree of heavy metals in small Cd > U > Pb > Cu > Co > Mn > Zn > Ni > V,the Cd and U is much severer and seriously harmful to ecology,the other heavy metal elements were slight pollution.The natural background value of Cd in the sampling area is likely to be higher than that of red soil in Guangdong Province,and the main pollution elements in sediments is U.3)Ostracode organisms in the surface sediments were bioassayed,the results show that: ostracod species is single,Dolerocypris ikeyal was only bioassayed in two samples,in which the content of radioactive elements U in surface water reached the maximal value.The content of U has obvious effect on the live of Ostracoda biological.All the above research results show that the surface water environment ecosystem is fragile and vulnerable to damage,Dolerocypris ikeyal may be a potentialsensitive species of uranium contamination in surface waters.