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Objective:To achieve rapid and accurate detection of trace uranium in drinking water by analyzing the factors influencing the accuracy of uranium measurement in drinking water using ultraviolet fluorescence method and by evaluating the uncertainty in measurement.Methods:The influence of acidity, Fe 3+ and Mn 2+ contents on the analitical result were studied to optimize the measurement conditions. The accuracy of the measurement method was verified in 7 laboratories. By studying the errors introduced in the process of standard preparation, sample pretreatment and measurement, the sources of uncertainty were analyzed and the uncertainty was synthesized. Results:At pH 1-11 in aqueous solution, the linear regression coefficient of the standard curve was greater than 0.995, which was in line with the linear measurement range of the instrument. At pH 12 or so, the linear regression coefficient was 0.761, which could not meet the measurement requirements. At pH<3 or pH>10, the increase in fluorescence count was lower, which might increase the measurement error. At Fe 3+ concentration ≥15 mg/L, a large deviation occurred in measurement value that could affect seriously measurement result. At Mn 2+ concentration ≥ 1.6 mg/L, the sample produced white precipitation, which could affect the measurement accuracy. Three spiked water samples with different concentrations were determined in 8 laboratories. Each water sample was measured six times in parallel. The relative standard uncertainty of the result were 6.42×10 -2, 4.48×10 -2 and 5.26×10 -2 μg/L, and the expanded uncertainties were 0.03, 0.06 and 0.12 μg/L( k=2), respectively. Conclusions:The optimum conditions for the determination of uranium in water using this method pH were in samples 3-10, the concentration of Fe 3+ less than 15 mg/L, and the concentration of Mn 2+ less than or equal to 1.6 mg/L. The main sources of uncertainty in the measurement of uranium in water using ultraviolet fluorescence method arise from the repeated measurement error and the volume of added standard solution.
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Objective:To study the influence of source thickness and counting efficiency calibration on the measurement of gross alpha activity in water.Methods:241Am and natural uranium reference materials were spiked in drinking water to prepare source on a planchet with different thickness, for counting alpha activity on the planchet. Results:The effective thickness measured by spiking 241Am or uranium standard solution in water sample was consistent with the empirical value of 4 mg/cm 2. The alpha counting rate was in a linear increase trend from 2A-5A mg/cm 2 and was basically stable and no longer increase when thickness was higher than 10A mg/cm 2 (A was area of planchet). The result calculated by effective thickness method and thick source method were in good agreement when thickness was 10A mg/cm 2. Conclusions:In order to reduce the deviation of gross alpha counting rate caused by the source thickness and counting efficiency calibration, the source thickness is recommended to be 10A mg/cm 2.
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Objective To establish an effective and reliable method for analysis of uhratrace uranium in multi-stage atmospheric particles providing the monitoring and evaluation of the content of radioactive uranium in the atmosphere.Methods A large volume six-stage-impactor sampler of atmosphere particles was used to collect aerosol samples,and uhratrace uranium in particles was digested using microwave and measured by inductively coupled plasma mass spectrometry.The filter material,digestion conditions and microwave digestion system had been optimized.Results The background of uranium level on the cellulose filter was the lowest,and the samples were digested by using HNO3-HCI (aqua regia)-H2O2 solution.Reference material SRM2783 was used to validate the accuracy of the method,and the relative error of the 238U was 7％,The detection limit of the method was 2 × 10-4ng/m3.The aerosol actual samples were analyzed using the established method.The mass concentrations of uranium in PM2.5 was in the range of 0.023-0.065 ng/m3.Conclusions The established method was effective and reliable to monitor the concentration level of ultratrace uranium in multi-stage atmospheric particles.
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Objective To investigate the activity concentration of 90St in tea produced in Chinese typical regions,enrich the baseline data for 90Sr level in Chinese tea,and evaluate possible exposure doses to people.Methods Samples were carbonized,ashed,digested and leached,and then extraction chromatography method was used to separate 90Sr and 90y.After preparation of sample source,radioactivity of 90Y was measured using low-level α/β counter.Results Twenty six kinds of tea produced in 16 typical regions from 26 cities of 16 provinces were collected in 2016,and their 90Sr activity concentrations were analyzed using the separation method of di (2-ethylhexyl) phosphate (HDEHP) extraction chromatography.The results revealed that the activity concentrations in 26 kinds of tea samples ranged from 0.28 to 3.78 Bq/kg,and contributed possible exposure doses of 0.44 × 10-2-6.00 × 10-2 μSv to each people.Conclusions These doses were far less than the ICRP annual dose limit of 1 mSv for the public,suggesting less impact on people's health.
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Objective To establish a method of analyzing total uranium and 235U/238U ratio in urine using inductively coupled plasma mass spectrometry (ICP-MS) and uncertainty assessment.Methods Urine sample was digested with HNO3 and H2O2,and total uranium was determined using ICP-MS method directly.The digested urine sample was separated to concentrate uranium with tributyl phosphate (TBP) column,and 235U/238U ratio was analyzed using ICP-MS.The uncertainty was evaluated through sample pre-treatment,measurement and standard curve calculation.Results The recovery of total uranium in urine was 98.4％-102.4％,detection limit was 0.002 μg/L.The relative expanded uncertainty of total uranium concentration in urine was 0.26 (k =2).235 U/238 U ratio was 0.001 1 (k =2).Conclusions This study offers a low detection limit,good recovery and precision method for rapid determination of total uranium and 235U/238 U ratio in urine samples.It is potential used for both in occupational exposure assessment and nuclear emergency situation.The uncertainty evaluation of total uranium and 235U/238U ratio in urine are reliable.
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OBJECTIVE: To observe the in vivo metabolism and distribution characteristics of nano-cerium oxide( nanoCeO_2) in rats,and to explore the radio-protective effect of nano-CeO_2. METHODS: i) A total of 18 specific pathogen free( SPF) SD rats were randomly divided into 3 groups. Rats of experiment group and CeO_2 blood group were gavaged with1. 0 g/kg body weight( bw) nano-CeO_2 suspension. Rats of control group were gavaged with double distilled water( DDW)in equal volume. At different time-points after treatment,venous blood was collected from the rats' eye socket in CeO_2 blood group,meanwhile urine and excrement of rats of experiment group were also collected. Organ and tissue samples of experiment group and control group were collected 24. 0 hours after treatment. The concentrations of cerium in biological samples were detected by inductively coupled plasma mass spectrometry. ii) A total of 72 SPF BALB/c mice were randomly divided into 6 groups. Mice of low-,medium-and high-dose groups were gavaged with 100,300 and 900 mg/kg bw nano-CeO_2 suspension respectively. Mice of negative control group,irradiation control group and drug positive control group were gavaged with DDW in equal volume once daily. After 14 days,mice of the other 5 groups were exposed by60Coγ-rays once with 3. 5 Gy( 1 Gy/min) except the negative control group. Mice of drug positive control group were given intraperitoneal injection with 200 mg/kg bw amifostine half an hour before irradiation. After exposure,mice were treated by the above gavages once daily. After 3 and 8 days,6 mice were randomly selected to collect the peripheral blood for the count of white blood cell( WBC) and lymph cell measuring. RESULTS: i) The cerium concentration in blood reached peak value in 4. 0 hours after exposure of nano-CeO_2,and the cerium concentration of urine and excrement reached maximum in8. 0 hours after exposure. After 24. 0 hours of exposure,the cerium concentration of brain in experiment group was higher than that of control group( P < 0. 05). Among the experiment group,the cerium concentrations of sternum,duodenum and brain were higher than that of kidney and heart( P < 0. 05),meanwhile the cerium concentrations of thymus and lung were higher than that of kidney( P < 0. 05). ii) There was no statistical difference in interactive effect of WBC count and lymph cell counts between nano-CeO_2 exposure ways and time( P > 0. 05). The WBC counts of the low-and medium-dose groups were lower than those of the negative control group and the drug positive control group( P < 0. 05). The WBC count of high-dose group was lower than those of irradiation control group,drug positive control group and medium-dose group( P <0. 05). The lymph cell counts of the 3 dose groups were lower than that of drug positive control group( P < 0. 05).CONCLUSION: The nano-CeO_2 is mainly cumulated in organs such as sternum,duodenum,brain,thymus and lung. After induced by radiation,nano-CeO_2 has a certain degree of promotion role in increasing the WBC counts.
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Objective To develop the method of analyzing α-radionuclides using large area grid ionization chamber.Methods Ultrasonic dispersion and vacuum drying system was used to prepare sample source,large standard thin source and plutonium plane source were used to optimize the working condition of spectrometer,and calibrate the instrument for analyzing α emitters.The certified reference materials (GBW04127) were used to verify the accuracy of the method.Results The non-linearity of calibration curve for standard thin sources of neptunium,plutonium and americium was less than 0.2％,and the resolution were 112,84 and 106 keV,respectively.The counting efficiency was 31.2％ for the large standard thin source.The values of specific activity measured in this way were in good agreement with those of the certified reference materials.232Th,238U,230Th,234U/226Ra,210Po,222Rn and 218Po were analyzed in a uranium mineral sample,and their specific radioactivity values were 5.3,3.8,35.6,21.4,27.0,19.6 and 11.1 Bq/g,respectively.Conclusions The method can be used to analyze α spectrum quickly in low-level radioactive environmental samples.
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Objective To develop a rapid and reliable method for determination of 210Po using large-area grid ionization chamber α spectrometry.Methods Samples were digested using a microwave digestion system.After preparation of sample source,the concentration of 210Po in clam was detected by large-area grid ionization chamber (φ 25 cm).209Po tracer was used to obtain the recovery.Results Large-area grid ionization chamber could achieve better counting and α spectrum resolution when the optimized thickness was 250 μg/cm2.By spiking 209Po tracer in clam,the minimum detectable activity was 9.870 × 10 4 Bq and the recovery of 210Po was 98％.Conclusions Compared with the traditional method,the developed method can avoid separation process,using less quantity of sample (0.2-0.5 g dry) and simplify the measurement process.This method may be has broad application prospects.
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Objective To ascertain the uranium isotopic ratios in surface water samples around nuclear power plants.Methods Water samples were collected in Jiangsu,Shandong and Zhejiang provinces.An efficient separation procedure for the trace uranium concentrated from surface water by tributyl phosphate (TBP) was used.Inductively coupled plasma mass spectrometry (ICP-MS) was applied to determination of low abundance uranium isotopes.Results The 234 U/238 U isotope ratio varied from 4.575 × 10-5to 7.752 × 10-5 and 235U/238U from 7.273 × 10-3 to 7.639 × 10-3.Conclusions The 234U is enriched in the surface water.
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Objective To ascertain the uranium concentrations and uranium isotopic ratios in drinking water in Xilingol League,the Inner Mongolia Autonomous Region.Methods Drinking water samples were collected in Xilingol League,the Inner Mongolia Autonomous.Region inductively coupled plasma mass spectrometry (ICP-MS) was applied to determine the concentration of uranium and uranium isotope abundance.Results The uranium concentrations in all samples were in the range of 2.73-18.9μg/L,with an average of 8.20 μg/L.Tbe234U/238U isotope ratio varied from 7.513 × 10-5to 3.003 × 10-4 and235U/238U from 7.196 × 10-3 to 7.391 × 10-3.The relative standard deviation (RSD) was less than 0.5％ for234U/238U and 0.2％ for235 U/238U.Conclusions The uranium concentration in samples collected from Dongwuqi was high than 15 μg/L,whih is the limit given by World Health Organization (WHO).The uranium in drinking water originates from the natural environment.The234U is enriched in drinking water.
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Objective To summarize the analytical results of radioactivity in the food and drinking water nationwide following the Fukushima nuclear accident,and to evaluate its possible contamination to the public health in China.Methods According to the national standard methods and IAEA,FDA correlative references,the scheme was established on sampling and measurements in food and drinking water after the breakout of the accident.The quality control was requested on the sampling,analyses and data report.Results Trace artificial radioactive isotope of 131I was measured in spinach samples on 2 April 2011 in Beijing. Subsequently 131I was found in 10 kinds of growing leaves vegetables (open field)nationwide.The maximum detectable activity of 131I in vegetables was about 3.1 Bq/kg.Since 3 May 2011,the concentration of 131I has been below the detection limits.No artificial radionulide was detectable in all of milk,drinking water and marine products samples during March to December,2011.Conclusions The food and drinking water measurements in China following the Fukushima nuclear accident denoted that the minor amounts of 131I in vegetables might result in very low absorbed dose and induce no impact on human health.The maximum detectable activity of 131I in vegetables was close to that reported in European countries,and much less than that measured in China immediately after the Chernobyl accident in 1986.
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Objective To ascertain the concentrations of uranium in drinking water around nuclear power plants.Methods A total of 106 water samples were collected from June 2009 to March 2010 in Jiangsu,Zhejiang,Liaoning and Shandong provinces.Inductively coupled plasma-msgs spectrometry(ICPMS)was applied to determine uranium content in local water source and drinking water.The detection limit of U was 0.8 ng/L.The recovery was 100.9%.Results The uranium concentrations in all samples were less than 15μg/L which was the limit given by World Health Organization(WHO).Conclusions The concentration of uranium in water sources was as follows:Liaoning>Shandong>Jiangsu>Zhejiang.The concentration of uranium in drinking water W88 maximal in Shandong Province and minimal in Zhejiang Province.