| The reserves of rare resources is abundant in our country and taking the lead inthe world. There have contain light rare resources richly in Mianning county，Sichuan province. Maoniuping is one of the largest ore block in Mianning county，Sichuan province. The exploitation of rare resources bring huge economic benefits tolocal, at the same time, due to the small-scale, extensive disordered mining of theseyears it also caused a series of environmental problems.This paper based on Sichuan province geological exploration fund "SichuanAnning valley lakes and mine ecological and geochemical environment survey"project. Through the field measurement of spectrometry data, as well as the resultsof laboratory analysis test samples, to analyze the radionuclide characteristics and radiation characteristics of research area. And evaluate the radioactive environmentand surface water quality in the study area, finally the corresponding preventionmeasures are put forward. Through the study, obtain some the conclusion following:Radionuclide in soil of Th, U content in the study area average19.43g/g and9.87g/g, higher than the world average and crustal abundance, Th/U mean value of2.9, below the world average soil and crustal abundance; The average of radionuclideTh content in water of0.010g/L; Radioactive nuclide U content of the average of0.37g/L, below the national average river mu (1.660g/L), slightly higher than theaverage level in the world the mu (0.309g/L);Th/U mean value of0.043;Radioactivenuclide of Th, U content in the stream sediment average of22.04g/g and9.33g/g,higher than other domestic regions of Th, U content in stream sediments, and alsohigher than the recommended background values in our country, the stream sedimentin the study area in Th/U mean value of3.81.Radionuclide238U,232Th specific activity value from the mining area to affected zone all showed a trend of decrease; Radionuclide specific activity40K value fromthe mining area to affected zone showed a trend of increase, this is because a largeamount of farmland affected zone distribution, due to various biogeochemical effect,makes the humic potassium concentration in clay.Radionuclide in soil in the study area of the environment within the averageexposure index of1.31, the average index of external exposure was0.43;Radionuclidegamma rays in the study area of the air absorbed dose rate averages186.54nGy/h,higher than the national and the world average; The average annual effective dose ratewas0.28mSv, evaluating standard of lower than the national limit0.595mSv and theevaluating standard of world limit0.46mSv.Analysis of water samples in the study area shows that ten indicators are notbeyond the national standard of" Emission Standards of Pollutants from Rare EarthsIndustry "regulation, therefore, the study area of water pollutant emissions meet thenational standards. Choose the method of comprehensive water quality identificationindex to evaluate the surface water in the studied area from: Maoniu river waterquality index of2.80.Comprehensive evaluation of Maoniu river Ⅲ for river waterquality, the water quality is better.Research in annual effective dose rate is lower than the recommendedbackground values in our country and the world recommend the background value, sothe radioactive environment as a whole in the study area is safe, but research inindividual level radioactive nuclide238U,232Th and specific activity of40K value ison the high side. Therefore, around the mining area within a certain range, master thereal time radioactive workplace radiation levels, in order to provide effectiveprotection measures are necessary. |
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