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1.
In this study, radioactivity levels of 228 lake water samples, 63 upper and depth sediment samples and 12 fish samples from Lake Van were investigated from 2005 to 2008 and the distribution patterns of the radionuclides were presented. Analysis included gross alpha–beta and total radium isotopes activities and uranium concentrations of the water, and gross alpha and gross beta activities and relevant 238U, 232Th and 40K activity of the sediment and fish samples of the lake. Mean gross alpha, gross beta and radium isotopes activities of lake water were found 0.74 ± 0.46, 0.02 ± 0.01 and 0.06 ± 0.04 Bq/L, respectively. Mean gross alpha and beta activities in upper and depth sediments were found to be 41 ± 6 and 1,514 ± 74 Bq/kg; 77 ± 5 and 394 ± 24 Bq/kg at a 95 % confidence level, respectively. Mean activities of 238U, 232Th and 40K activity concentrations in upper and depth sediments were determined to be 225 ± 22, 70 ± 7 and 486 ± 39 Bq/kg; 174 ± 4, 63 ± 3 and 263 ± 25 Bq/kg, respectively. The mean gross alpha and beta, 238U, 232Th and 40K aktivities in fish samples were established as 47 ± 18, 470 ± 12, 0.57 ± 0.220, 0.022 ± 0.006, 319 ± 11 Bq/kg, respectively. The transfer factor from lake water to fish tissues, annual intake by humans consuming fish, and annual committed effective doses were estimated and evaluated.  相似文献   

2.
Biogenic burning as forest fire phenomena occurring from April to August each year in the Sumatra and Borneo islands are major sources of biogenic uranium–thorium decay series in marine systems. 30 samples were collected during the Ekspedisi Pelayaran Saintifik Perdana 2009 cruise (EPSP 2009 cruise) between 12th June and 1st August 2009 from the Straits of Malacca to the Sulu and Sulawesi Seas to study the effect of haze and the monsoon season on the deposition rate of 210Po and 210Pb in Malaysian waters. All samples were spiked with 1 ml of lead [Pb(NO3)2; 25 mg ml?1] and 0.05 ml of Polonium-209 tracer (26.08 dpm ml?1). 210Po activity was determined by auto plating onto silver foil and counting using an alpha spectrometry system (Canberra model Alpha Analyst with a silicon-surface barrier detector). Lead that was collected via electrodeposition, formed lead sulphate (PbSO4) precipitation. This precipitate was wrapped onto plastic discs and counted for 210Pb beta activity using a gross alpha–beta counting system (Tennelec model LB-5100 low background gas-flowing anti-coincidence alpha/beta counter) after 1 month to allow bismuth ingrowths. The range of 210Po activities varied between 51.08 ± 15.1 and 742.08 ± 220.34 Bq/kg, whereas the activity of 210Pb ranged from 31.10 ± 4.20 to 880.23 ± 123.86 Bq/kg and 210Po/210Pb ratio value varied between sampling stations from 0.19 to 13.77. The contents of 210Po were also statistically positively correlated with the amount of total suspended particulate especially those recorded during heavy haze period events.  相似文献   

3.
A new method for the determination of radiostrontium in seawater samples has been developed at the Savannah River National Laboratory (SRNL) that allows rapid pre-concentration and separation of strontium and yttrium isotopes in seawater samples for measurement. The new SRNL method employs a novel and effective pre-concentration step that utilizes a blend of calcium phosphate with iron hydroxide to collect both strontium and yttrium rapidly from the seawater matrix with enhanced chemical yields. The pre-concentration steps, in combination with rapid Sr Resin and DGA Resin cartridge separation options using vacuum box technology, allow seawater samples up to 10 L to be analyzed. The total 89Sr + 90Sr activity may be determined by gas flow proportional counting and recounted after ingrowth of 90Y to differentiate 89Sr from 90Sr. Gas flow proportional counting provides a lower method detection limit than liquid scintillation or Cerenkov counting and allows simultaneous counting of samples. Simultaneous counting allows for longer count times and lower method detection limits without handling very large aliquots of seawater. Seawater samples up to 6 L may be analyzed using Sr Resin for 89Sr and 90Sr with a minimum detectable activity (MDA) of 1–10 mBq/L, depending on count times. Seawater samples up to 10 L may be analyzed for 90Sr using a DGA Resin method via collection and purification of 90Y only. If 89Sr and other fission products are present, then 91Y (beta energy 1.55 MeV, 58.5 day half-life) is also likely to be present. 91Y interferes with attempts to collect 90Y directly from the seawater sample without initial purification of Sr isotopes first and 90Y ingrowth. The DGA Resin option can be used to determine 90Sr, and if 91Y is also present, an ingrowth option with using DGA Resin again to collect 90Y can be performed. An MDA for 90Sr of <1 mBq/L for an 8 h count may be obtained using 10 L seawater sample aliquots.  相似文献   

4.
We developed a new method for the determination of 227Ac in geological samples. The method uses extraction chromatographic techniques and alpha-spectrometry and is applicable for a range of natural matrices. Here we report on the procedure and results of the analysis of water (fresh and seawater) and rock samples. Water samples were acidified and rock samples underwent total dissolution via acid leaching. A DGA (N,N,N′,N′-tetra-n-octyldiglycolamide) extraction chromatographic column was used for the separation of actinium. The actinium fraction was prepared for alpha spectrometric measurement via cerium fluoride micro-precipitation. Recoveries of actinium in water samples were 80 ± 8 % (number of analyses n = 14) and in rock samples 70 ± 12 % (n = 30). The minimum detectable activities (MDA) were 0.017–0.5 Bq kg?1 for both matrices. Rock sample 227Ac activities ranged from 0.17 to 8.3 Bq kg?1 and water sample activities ranged from below MDA values to 14 Bq kg?1of 227Ac. From the analysis of several standard rock and water samples with the method we found very good agreement between our results and certified values.  相似文献   

5.
Tritium activity in potable drinking water samples from Adana city were measured using liquid scintillation counting after distillation procedure. The results exposed that the activity concentrations of the tritium measured in one-third of these samples were lower than minimum detectable activity which has a value of 2 Bq/L for counting time of 1,500 min. However, the maximum and mean value of the tritium activity was found to be 9.1 Bq/L (77.3 TU) and 7.0 Bq/l (59.4 TU), respectively. These values were substantially below the 100 Bq/L which is normative limit in Turkey for waters intended for human consumption. The highest values of annual effective dose received by infants, children and adults due to measured tritium activity were estimated as 0.041, 0.057 and 0.120 μSv/y, respectively.  相似文献   

6.
There have been developed several different methods for measuring radon concentration in water which are now widely used, such as: liquid scintillation counting, Lucas cell counting, gamma and alpha spectroscopy. However, as far as the radon measurements in carbonated water are concerned, there are some issues caused by the gas excess. The aim of our work was to develop a simple method for measuring radon concentration in carbonated water that can be used for in situ measurements. Nevertheless, we propose not one, but two methods for measuring radon concentration in carbonated water. Thus, the first one is based on Lucas scintillation cells, and can be used for on-site measurements, while the second one utilizes activated charcoal adsorption, and needs a setup laboratory for gamma spectrometry measurements. For the evaluation of the methods, we compared the results of the Lucas cell-Luk3C method and of the activated charcoal method, both for non-carbonated and carbonated water. The simplest method for radon concentration determination—Lucas cell method—was successfully applied to fourteen natural carbonated water samples from Borsec to Bilbor area. The radon concentrations obtained ranged from 5.6 ± 0.5 to 39.6 ± 4.0 Bq/L, with a mean of 15.9 ± 2.6 Bq/L, these values are lower than 100 Bq/L, the maximum value recommended by the World Health Organization.  相似文献   

7.
In our institute, different procedures have been developed to measure the radioactivity content of drinking water both in normal and in emergency situations, such as those arising from accidental and terrorist events. A single radiometric technique, namely low level liquid scintillation counting (LSC), has been used. In emergency situations a gross activity screening is carried out without any sample treatment by a single and quick liquid scintillation counting. Alpha and beta activities can be measured in more than one hundred samples per day with sensitivities of a few Bq/L. Higher sensitivity gross alpha and beta, uranium and radium measurements can be performed on water samples after specific sample treatments. The sequential method proposed is designed in such a way that the same water sample can be used in all the stages, with slight modifications. This sequential procedure was applied in a survey of the Lombardia district. At first tap waters of the 13 largest towns were examined, then a more detailed monitoring was carried out in the surroundings of Milano and Lodi towns. The high sensitivity method for the determination of uranium isotopes was used to check the presence of depleted uranium in Lake Garda. Reduced equipment requirements and relative readiness of radiochemical procedures make LSC an attractive technique which can also be applied by laboratories lacking specific radiochemistry facilities and experience.  相似文献   

8.
Distribution of natural radionuclide gives significant parameter to assess the presence of gamma radioactivity and its radiological effect in our environment. Natural radionuclides are present in the form of 226Ra, 232Th and 40K in soil, rocks, water, air, and building materials. Distribution of natural radionuclides depends on the type of minerals present in the soil and rocks. For this purpose gamma spectrometer is used as tool for finding the concentration of these radionuclides. The activity concentration of naturally occurring radionuclides 226Ra, 232Th and 40K in these soil samples were found to vary from of 8 ± 1 Bq/kg to 50 ± 10 Bq/kg with an average 20 Bq/kg, 7 ± 1–88 ± 16 Bq/kg with an Average 26 Bq/kg and 115 ± 18–885 ± 132 Bq/kg with an average 329 Bq/kg, respectively. In this paper, we are presenting the radiological effect due to distribution of natural radionuclide present in soil of Garhwal Himalaya.  相似文献   

9.
The method developed for cesium concentration from large freshwater samples was tested and adapted for analysis of cesium radionuclides in seawater. Concentration of dissolved forms of cesium in large seawater samples (about 100 L) was performed using composite absorbers AMP-PAN and KNiFC-PAN with ammonium molybdophosphate and potassium–nickel hexacyanoferrate(II) as active components, respectively, and polyacrylonitrile as a binding polymer. A specially designed chromatography column with bed volume (BV) 25 mL allowed fast flow rates of seawater (up to 1,200 BV h?1). The recovery yields were determined by ICP-MS analysis of stable cesium added to seawater sample. Both absorbers proved usability for cesium concentration from large seawater samples. KNiFC-PAN material was slightly more effective in cesium concentration from acidified seawater (recovery yield around 93 % for 700 BV h?1). This material showed similar efficiency in cesium concentration also from natural seawater. The activity concentrations of 137Cs determined in seawater from the central Pacific Ocean were 1.5 ± 0.1 and 1.4 ± 0.1 Bq m?3 for an offshore (January 2012) and a coastal (February 2012) locality, respectively, 134Cs activities were below detection limit (<0.2 Bq m?3).  相似文献   

10.
Organic sedimentary rock samples were collected from three Oil Wells in the North-Western Niger Delta, Nigeria in order to determine their natural radioactivity and elemental geochemistry, with the aim of determining the concentrations of major radionuclides and their radiological and environmental health implication. The PIXE method of IBA technique and an accurately calibrated Si(Li) detector system was used to measure the elemental concentration of the sediment samples. The radionuclides identified belong to the decay series of naturally occurring radionuclides headed by 238U and 232Th along with the non-decay series radionuclide, 40K. The activity concentrations of the radionuclides and their derived dose were then calculated. The average activity concentrations of 40K were 248 Bq/kg for Well A, 261 Bq/kg for Well B and 273 Bq/kg for Well C. For 232Th the activity concentrations were 1,043 Bq/kg for Well A, 1,400 Bq/kg for Well B, 1,434 Bq/kg for Well C. 238U activity concentrations were 2,210, 3,508 and 250 Bq/kg for the Oil Wells A, B, C, respectively. The equivalent dose ranges from 8.5 ± 1.1 to 24.3 ± 2.1 mSv/year with a mean of 14.5 ± 2.2 mSv/year for Oil Well A, 2.4 ± 0.1–75.0 ± 1.2 mSv/year with a mean of 21.5 ± 1.1 mSv/year for Oil Well B and 3.7 ± 0.2–10.7 ± 0.6 mSv/year with a mean of 9.4 ± 2.5 for Oil Well C. The detected trace metals were majorly V, Ni, Pb, Fe, Cr, Cu, Zn, Co and their concentrations together with those of the radionuclides are compared with the relevant world standard limits. The results obtained were high, and hence, the radioactivity level and trace element content of the sediment samples from the North-Western Niger Delta Oil province could constitute health hazard to occupationally exposed workers, and to the public if not properly disposed. However, despite the careful disposal practice claims by the Oil industries, and given the high concentrations, the sediments could still pose an intrinsic health hazard considering their cumulative effects in the environment.  相似文献   

11.
In this work, we collected 101 geothermal water samples to investigate comprehensively the radioactivity of geothermal water in Beijing. The concentrations of gross beta, 226Ra and 222Rn were measured and the obtained values were in the range of 0.032–7.060, 0.023–0.363 and 0.470–29.700 Bq/L, respectively. The samples with higher concentration of 222Rn were found to be located near large faults. The effective dose of 222Rn in the air for three cases were calculated to be greater than radiation dose limit of 1 mSv/a.  相似文献   

12.
This study is part of an effort to assess the level of background radiation for Erzincan Province of eastern Turkey. Radionuclide activity concentrations in soil samples were measured through gamma-ray spectrometry and the average activities were determined as 8.93, 11.39, 281.94, and 9.52 Bq/kg for the radionuclides 238U, 232Th, 40K, and 137Cs, respectively. The average annual effective dose from these natural radioactivity sources (238U series, 232Th series and 40K,) was calculated to be 27.9 μSv. Radioactivity levels in drinking and potable water samples were studied using a multi-channel low level proportional counter. The average gross alpha activity concentration was found to be 0.0477 Bq/L (min. 0.007 Bq/L; max. 0.421 Bq/L) and the average gross beta activity was measured as 0.104 Bq/L (min. 0.008 Bq/L; max. 1.806 Bq/L). These values lead to an average annual effective dose of 9.75 μSv from the alpha emitters and 56.34 μSv from the beta emitting radionuclides in water. The radioactivity levels in the water samples investigated were found to comply with the reference levels recommended by WHO and the regulations set forth by the Turkish Health Ministry.  相似文献   

13.
Measurement of 3H, 14C, 32P, 35S, 125I, and 131I in radioisotope (RI) waste materials such as the vials, pipette tips, tubes, syringes, and paper generated from the industrial, medical, educational, and research organizations were conducted by a wet oxidation method. Counts were obtained by a liquid scintillation counter for 3H, 14C, and 32P; a gas proportional counter for 35S; a low energy photon spectroscopy for 125I; and an HPGe detector for 131I. After the treatment of approximately 20 g of the sample, the counting value was determined to obtain a minimum detectable activity (MDA) of approximately 1 × 10?3 ~ 5 × 10?2 Bq/g. The specific activities of shor-half-life RIs (32P, 35S, 125I, and 131I) were not detectable and/or resulted in a low value (<1 Bq/g). The waste containing 3H and 14C was observed to have the specific activities in the range of 10?2–105 and 10?2–104 Bq/g, respectively.  相似文献   

14.
Rapid determination of gross alpha and beta emitters in urine by liquid scintillation counting is discussed. This method is based on direct addition of urine into scintillation cocktail. 241Am, 239Pu and 90Sr were selected as model radionuclides. The LSA Hidex 300 SL equipped with Triple-Double-Coincidence-Ratio technique was used for sample measurement. The work focused on optimizing the LSC cocktail to urine volume ratio with respect to the model radionuclides. The overall efficiencies for 241Am, 239Pu and 90Sr were greater than 92 %; therefore, this method would be suitable for rapid determination of gross alpha/beta activity.  相似文献   

15.
In this study, soil samples were collected at Canadian embassy in Tokyo (about 300 km from Fukushima) on 23 March and 23 May of 2011 for purposes of estimating concentrations of radionuclides in fallout, the total fallout inventory, the depth distribution of radionuclide of interest and the elevated ambient gamma dose-rate at this limited location. Some fission products and actinides were analyzed using gamma-ray spectrometry, alpha spectrometry and liquid scintillation counting. The elevated activity concentration levels of 131I, 132I, 134Cs, 137Cs, 136Cs, 132Te, 129mTe, 129Te, 140Ba and 140La were measured by the gamma-ray spectrometer in the first sample collected on 23 March. Two months after the accident, the 134Cs and 137Cs became only detectable nuclides. A mass relaxation depth of 3.0 g/cm2 was determined by the activities on the depth distribution of 137Cs in a soil core. The total fallout inventory was thus calculated as 225 kBq/m2 on March sampling date and 25 kBq/m2 on May sampling date. The ambient gamma dose-rates in the sampling area estimated by the fallout fission products inventory and 137Cs depth distribution ranged from 184 to 38 nGy/h. There was no detectable americium or plutonium in the soil samples by alpha spectrometry. Although 90Sr or 89Sr were detected supposedly as a result of this accident, it was less than the detection limit, which was about 0.4 Bq/kg in the soil samples.  相似文献   

16.
A study to evaluate conditions affecting the determination of 90Sr/90Y activities in liquid samples by the triple-to-double coincidence ratio (TDCR) Cherenkov counting technique was conducted. The Cherenkov radiation produced by the 90Y beta decay was determined using a commercially available Hidex 300 SL liquid scintillation counter. The interferences of sample geometry, including sample counting vial type and volume composition, and sample colour on the TDCR were investigated. The effects of potentially interfering beta and mixed beta–gamma emitters on the TDCR Cherenkov counting of 90Sr/90Y activities were also examined. The TDCR values were used to quantify counting efficiencies of 90Y under different experimental conditions. The results demonstrated that the Cherenkov counting efficiency of 90Y is independent of sample volume and counting vial size. The effect of colour quenching was examined using yellow and brown food-grade dyes. The TDCR correction for colour quenching was found to be effective. An evaluation of counting efficiency of different beta-emitting radionuclides demonstrated that strong gamma emissions can contribute to the Cherenkov counting efficiency. Overall, measured radioactivity values deviated from reference values by ≤7.5 %, which is acceptable for screening applications in emergency situations.  相似文献   

17.
Ten ore samples, two unpurified yellow cake samples and natural uranyl nitrate hexahydrate sample were analyzed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) method to verify source nuclear material. Samples represent source nuclear material as possible. All samples were scanned at ideal conditions; working distance = 10 mm, voltage = 30 kV, magnification value = × 100, spot size = 50 to screen samples for the presence of uranium and thorium, Also Hyper pure germanium (HPGe) gamma spectrometers were applied to estimate the uranium and thorium contents in Bq/kg (ppm). For the ore samples uranium-238 ranges from 1,049.23 Bq/kg (85.30 ppm) to 2,096.06 Bq/kg (170.41 ppm), uranium-235 ranges from 47.51 to 105.61 Bq/kg and thorium-232 ranges from 22.84 Bq/kg (5.65 ppm) to 41.78 Bq/kg (10.34 ppm). For the yellow cake samples and uranyl nitrate hexahydrate uranium-238 ranges from 42.99 Bq/kg (3.50 ppm) to 71,887.2 Bq/kg (5,844.49 ppm) and thorium-232 is 4.78 Bq/kg (1.83 ppm) and the other two samples are lower than the detection limit.  相似文献   

18.
Liquid scintillation counting (LSC) and pulse shape analysis (PSA) was used in measuring radon and gross alpha- and beta-activities in groundwater. We used conventional LSC counters for the measurement of radon in water, but low-background LSC spectrometers for the gross activity measurements. The lower limit of detection (LLD) for radon in water is 0.6 Bq/l for a 60 min count with a conventional counter, but 0.1 or 0.2 Bq/l, with the two types of low-background LSC spectrometers equipped with a pulse shape analyser (PSA). The gross alpha and beta activity measurements are made using a simple sample preparation method, PSA of a low background LSC and spectrum analysis. The LLD recorded for gross alpha and beta with the two spectrometers are 0.02 and 0.03 Bq/l and 0.2 and 0.4 Bq/l, respectively, for a 180 minutes count and a 38 ml sample volume. The method also enable the calculation of the U and226Ra contents in water and indicates the presence of some other long-lived radionuclides (210Pb,228Ra or40K). The LLD for U recorded with both spectrometers is 0.02 Bq–1 and for226Ra 0.01 Bq·1–1. The LLDs attained by this LSC method are two orders of magnitude lower than the maximum permissible concentrations set for U and226Ra.  相似文献   

19.
Summary The standard procedure for analyzing gross alpha and gross beta in water is evaporation of the sample and radioactivity determination of the resultant solids by proportional counting. This technique lacks precision, and lacks sensitivity for samples with high total dissolved solids. Additionally, the analytical results are dependent on the choice of radionuclide calibration standard and the sample matrix. Direct analysis by liquid scintillation counting has the advantages of high counting efficiencies and minimal sample preparation time. However, due to the small sample aliquants used for analysis, long count times are necessary to reach required detection limits. The procedure proposed consists of evaporating a sample aliquant to dryness, dissolving the resultant solids in a small volume of dilute acid, followed by liquid scintillation counting to determine radioactivity. This procedure can handle sample aliquants containing up to 500 mg of dissolved solids. Various acids, scintillation cocktail mixtures, instrument discriminator settings, and regions of interest (ROI) were evaluated to determine optimum counting conditions. Precision is improved and matrix effects are reduced as compared to proportional counting. Tests indicate that this is a viable alternative to proportional counting for gross alpha and gross beta analyses of water samples.  相似文献   

20.
A new rapid method for the determination of actinides in seawater samples has been developed at the Savannah River National Laboratory. The actinides can be measured by alpha spectrometry or inductively-coupled plasma mass spectrometry. The new method employs novel pre-concentration steps to collect the actinide isotopes quickly from 80 L or more of seawater. Actinides are co-precipitated using an iron hydroxide co-precipitation step enhanced with Ti+3 reductant, followed by lanthanum fluoride co-precipitation. Stacked TEVA Resin and TRU Resin cartridges are used to rapidly separate Pu, U, and Np isotopes from seawater samples. TEVA Resin and DGA Resin were used to separate and measure Pu, Am and Cm isotopes in seawater volumes up to 80 L. This robust method is ideal for emergency seawater samples following a radiological incident. It can also be used, however, for the routine analysis of seawater samples for oceanographic studies to enhance efficiency and productivity. In contrast, many current methods to determine actinides in seawater can take 1–2 weeks and provide chemical yields of ~30–60 %. This new sample preparation method can be performed in 4–8 h with tracer yields of ~85–95 %. By employing a rapid, robust sample preparation method with high chemical yields, less seawater is needed to achieve lower or comparable detection limits for actinide isotopes with less time and effort.  相似文献   

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