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1.
Levels of depleted uranium in Kosovo soils   总被引:2,自引:0,他引:2  
The United Nations Environment Programme (UNEP) has performed a field survey at 11 sites located in Kosovo, where depleted uranium (DU) ammunitions were used by the North Atlantic Treaty Organization (NATO) during the last Balkans conflict (1999). Soil sampling was performed to assess the spread of DU ground contamination around and within the NATO target sites and the migration of DU along the soil profile. The 234U/238U and 235U/238U activity concentration ratios have been used as an indicator of natural against anthropogenic sources of uranium. The results show that levels of 238U activity concentrations in soils above 100 Bq x kg(-1) can be considered a 'tracer' of the presence of DU in soils. The results also indicate that detectable ground surface contamination by DU is limited to areas within a few metres from localised points of concentrated contamination caused by penetrator impacts. Vertical distribution of DU along the soil profile is measurable up to a depth of 10-20 cm. This latter aspect is of particular relevance for the potential risk of future contamination of groundwater.  相似文献   

2.
The use of depleted uranium ammunition in South Serbia during the 1999 Kosovo conflict raised a great deal of public concern in the Balkans. Radioactivity levels of 238U in 20 wells and lake water samples were checked from the viewpoint of internal radiation exposure for South Serbian subjects. We have measured 238U concentration using inductively coupled plasma mass spectrometry, whereas thermal ionisation mass spectrometry has been used for the measurement of isotope ratios, e.g. 234U/238U and 235U/238U. The concentration of uranium in water samples varies in the range 1.37-63.18 mBq/L. 234U belongs to the 238U natural radioactive decay series, and at secular equilibrium, the abundance ratio, 234U/238U, corresponds to the ratio of their half-lives. The 234U/238U activity ratio varies in the range 0.88-2.2 and 235U/238U isotope ratio varies from 0.00698 to 0.00745. These findings indicate that uranium in water was a mixture of natural and anthropogenic origin. The annual effective dose due to 238U was estimated to be in the range 9.2 x 10(-5)-2.1 x 10(-3) mSv.  相似文献   

3.
This study assesses the level of background radiation for Kayseri province of Turkey. Natural radionuclide activity concentrations in soil samples were determined using high-resolution gamma spectroscopy. Outdoor gamma dose measurements in air at 1 m above ground level were determined using a portable gamma scintillation detector. The obtained results of uranium and thorium series as well as potassium ((40)K) are discussed. The present data were compared with the data obtained from different areas in Turkey. From the measured gamma-ray spectra, the average activity concentrations were determined for (238)U (range from 3.91 to 794.25 Bq kg(-1)), (232)Th (range from 0.68 to 245.55 Bq kg(-1)) and (40)K (range from 23.68 to 2718.71 Bq kg(-1)). The average activity concentrations of (238)U, (232)Th and (40)K were found to be 35.51, 37.27 and 429.66 Bq kg(-1), respectively, and 11.53 Bq kg(-1) for the fission product (137)Cs. The highest values of (238)U, (232)Th and (40)K concentrations (794.25 Bq kg(-1), 245.55 Bq kg(-1), 2718.71 Bq kg(-1), respectively) were observed in abnormal samples at Hayriye village. The average outdoor gamma dose rate in air at 1 m above the ground was determined as 114.43 nGy h(-1). Using the data obtained in this study, the average annual effective dose for a person living in Kayseri was found to be about 140.34 μSv.  相似文献   

4.
Annual effective dose equivalent due to natural gamma radiation from (238)U, (232)Th and (40)K have been evaluated from granites in Turkey. Forty samples were taken for spectrometric analysis. Specific concentrations of (238)U, (232)Th and (40)K in granite samples were determined. Spectroscopy system was used with 1.8 keV (FWHM) coaxial high purity germanium (HPGe) detector. Average values of concentrations of (238)U, (232)Th and (40)K were detected at 15.85, 33.76 and 359 Bq kg(-1), respectively. The average value of radon varies from 0.073 to 0.185 Bq m(-2) h(-1) exhalation depends on the specific concentration of uranium. The dose rate due to this highest activity which have been evaluated by a Monte Carlo transport calculations does not exceed 0.4 mSv a(-1).  相似文献   

5.
Inductively coupled plasma mass spectrometry (ICP-MS), coupled with a large-bore direct injection high efficiency nebulizer (LB-DIHEN), was utilized to determine the concentration and isotopic ratio of uranium in 11 samples of synthetic urine spiked with varying concentrations and ratios of uranium isotopes. Total U concentrations and (235)U/(238)U isotopic ratios ranged from 0.1 to 10 microg/L and 0.0011 and 0.00725, respectively. The results are compared with data from other laboratories that used either alpha-spectrometry or quadrupole-based ICP-MS with a conventional nebulizer-spray chamber arrangement. Severe matrix effects due to the high total dissolved solid content of the samples resulted in a 60 to 80% loss of signal intensity, but were compensated for by using (233)U as an internal standard. Accurate results were obtained with LB-DIHEN-ICP-MS, allowing for the positive identification of depleted uranium based on the (235)U/(238)U ratio. Precision for the (235)U/(238)U ratio is typically better than 5% and 15% for ICP-MS and alpha-spectrometry, respectively, determined over the concentrations and ratios investigated in this study, with the LB-DIHEN-ICP-MS system providing the most accurate results. Short-term precision (6 min) for the individual (235)U and (238)U isotopes in synthetic urine is better than 2% (N = 7), compared to approximately 5% for conventional nebulizer-spray chamber arrangements and >10% for alpha-spectrometry. The significance of these measurements is discussed for uranium exposure assessment of Persian Gulf War veterans affected by depleted uranium ammunitions.  相似文献   

6.
Natural radioactivity in drinking water was determined in population-based random study of 472 private wells. The mean concentrations of (222)Rn, (226)Ra, (234)U, (238)U, (210)Pb and (210)Po in drilled wells were 460, 0.05, 0.35, 0.26, 0.04 and 0.05 Bq l(-1), and in wells dug in the soil were 50, 0.016, 0.02, 0.015, 0.013 and 0.007 Bq l(-1), respectively. Approximately 10% of the drilled wells exceeded a radon concentration of 1000 Bq l(-1) and 18% a uranium concentration of 15 microg l(-1). The mean annual effective dose from natural radionuclides for a drilled well user was 0.4 mSv and 0.05 mSv for a user of a well dug in the soil. The effective dose arising from (222)Rn was 75% of the total of all natural radionuclides for drilled well users. As regards long-lived radionuclides, (210)Po and (210)Pb caused the largest portion of the effective dose. The dose arising from (238)U, (234)U and (226)Ra was only 8% of the total of all natural radionuclides.  相似文献   

7.
At Dounreay, there are a number of facilities in which the main radiological hazard is the intake of uranium. The hazard is managed through the implementation of controls and contamination surveys in order to reduce the risk of intake. In order to provide reassurance that radiological significant intakes are not taking place, a routine urine sample programme is in place. As well as being exposed to work place sources of uranium workers are also exposed to the intake of uranium from foodstuffs and water, which are not associated with their work at Dounreay. In order to characterise the intake of the radionuclides from the environment, urine samples were collected from a group of Dounreay personnel who are not exposed to uranium in their workplace. The distribution of the uranium isotopes 234U, 235U and 238U has been assessed for these workers. The distributions will be used to assess the likelihood of uranium detected in urine for a uranium worker being due to an intake in the workplace. The best match to distributions of 234U and 238U was found to be a combination of normal and lognormal distributions.  相似文献   

8.
Specific activity of (235)U and (238)U in soil and fertiliser samples from Guellal region in Setif (Algeria) was determined by gamma-ray spectrometry. The selected phosphate fertilisers samples were collected from two types of fertilisers NPK (N, nitrogen; P, phosphorus; K, potassium) and NPKs (sulphate-based NPK). These last ones are used to fertilise the studied area as well as a radioactivity comparison between the soils before and after fertilisation. NPK and NPKs fertilisers have presented higher concentrations of the radionuclide (238)U, up to 1125 and 1545 Bq kg(-1), respectively. For soils before and after fertilisation, the concentrations of (238)U were, respectively, 252.8 and 316.2 Bq kg(-1). The average value and range of measured concentration of (235)U for soils before fertilisation was 12.16 ± 1.4 Bq kg(-1) and for the fertilised soils was 15.16 ± 1.8 Bq kg(-1), whereas the corresponding values for NPK and NPKs fertilisers were, respectively, 49.38 ± 5.7 and 50.61 ± 5.2 Bq kg(-1).  相似文献   

9.
The volume activity of 3H, 90Sr, 137Cs, 234U, 235U, 238U, 238Pu, 239+240Pu, and 241Am in ground waters from observation holes 1-G-6-G in the north section of the Shelter local area of the Chernobyl Nuclear Power Plant (CNPP) was measured. The distribution of radionuclides in the suspension fractions of the ground waters was evaluated. The main contribution to the pollution of ground waters with uranium is due to natural uranium isotopes: 234,235,238U. The activity ratios of 238Pu, 239+240Pu, and 241Am in ground waters are similar to those in the spent fuel of 4th CNPP block.  相似文献   

10.
Abdellah  W. M. 《Radiochemistry》2019,61(4):470-477
Radiochemistry - Gamma and alpha spectrometry techniques were applied to determine the activity concentrations of 238U and 232Th (Bq kg–1) as well as the 234U/238U and 230Th/234U isotopic...  相似文献   

11.
Uranium isotope ratios can provide source information for tracking uranium contamination in a variety of fields, ranging from occupational bioassay to monitoring aftereffects of nuclear accidents. We describe the development of isotope selective laser ionization spectrometry for ultratrace measurement of the minor isotopes (234)U, (235)U, and (236)U with respect to (238)U. The inherent isotopic selectivity of three-step excitation with single-mode continuous wave lasers results in measurement of the minor isotopes at relative abundances below 1 ppm and is not limited by isobaric interferences such as (235)UH(+) during measurement of (236)U. This relative abundance limit is attained without mass spectrometric analysis of the laser-created ions. Uranyl nitrate standards from an international blind comparison were used to test analytical performance for different isotopic compositions and with quantities ranging from 11 ng to 10 microg total uranium. Isotopic ratio determination was demonstrated over a linear dynamic range of 7 orders of magnitude with a few percent relative precision and detection limits below 500 fg for the minor isotopes.  相似文献   

12.
Radiation workers at Atomic Weapons Establishment (AWE) are monitored for uranium exposure by routine bioassay sampling (primarily urine sampling). However, the interpretation of uranium in urine and faecal results in terms of occupational intakes is difficult because of the presence of uranium due to intakes from environmental (dietary) sources. For uranium in urine data obtained using current analytical techniques at AWE, the mean, median and standard deviation of excreted uranium concentrations were 0.006, 0.002 and 0.012 μg per g creatinine, respectively. These values are consistent with what might be expected from local dietary intakes and the knowledge that occupational exposures at AWE are likely to be very low. However, some samples do exceed derived investigation levels (DILs), which have been set up taking account of the likely contribution from environmental sources. We investigate how the activity and isotopic composition of uranium in the diet affects the sensitivity of uranium in urine monitoring for occupational exposures. We conclude that DILs based on both total uranium in urine activity and also (234)U:(238)U ratios are useful given the likely variation in dietary contribution for AWE workers. Assuming a background excretion rate and that the enrichment of the likely exposure is known, it is possible to assess exposures using (234)U:(238)U ratios and/or total uranium activity. The health implications of internalised uranium, enriched to <5-8 % by mass (235)U, centre on its nephrotoxicity; the DILs for bioassay samples at AWE are an order of magnitude below the conservative recommendations made by the literature.  相似文献   

13.
Kinetics of dissolution of (238)U, (234)U and (230)Th dust deposited on filters from personal alpha dosemeters was studied by means of a 26-d in vitro dissolution test with a serum ultrafiltrate simulant. Dosemeters had been used by miners at the uranium mine 'Dolní Rozínka' at Rozná, Czech Republic. The sampling flow-rate as declared by the producer is 4 l h(-1) and the sampling period is typically 1 month. Studied filters contained 125 +/- 6 mBq (238)U in equilibrium with (234)U and (230)Th; no (232)Th series nuclides were found. Half-time of rapid dissolution of 1.4 d for (238)U and (234)U and slow dissolution half-times of 173 and 116 d were found for (238)U and (234)U, respectively. No detectable dissolution of (230)Th was found.  相似文献   

14.
The activity concentrations of 137Cs, 40K, 232Th, 238U and 226Ra were measured in surface soil samples from East and South of Marmara region, Turkey. The physico-chemical parameters (organic matter, CaCO3 contents and pH-value) of the soil samples were determined in the samples collected from 100 sampling stations. The average activity concentrations of 137Cs, 40K, 232Th, 238U and 226Ra were found to be 27.46+/-21.84, 442.51+/-189.85, 26.63+/-15.90, 21.77+/-12.08 and 22.45+/-13.31 Bq kg(-1), respectively. The mean value of total annual external gamma radiation dose equivalent for the natural radionuclides was calculated to be 54.86 microSv. The current data were compared with those found in the other locations of Turkey and different countries.  相似文献   

15.
The activity concentrations of naturally occurring radionuclides ((238)U, (226)Ra, (228)Ra, (210)Pb and (40)K) in Jordanian phosphate ore, fertilizer material and phosphogypsum piles were investigated. The results show the partitioning of radionuclides in fertilizer products and phosphogypsum piles. The outcome of this study will enrich the Jordanian radiological map database, and will be useful for an estimation of the radiological impact of this industrial complex on the immediate environment. The activity concentration of (210)Pb was found to vary from 95 +/- 8 to 129 +/- 8 Bq kg(-1) with a mean value of 111 +/- 14 Bq kg(-1) in fertilizer samples, and from 364 +/- 8 to 428 +/- 10 Bq kg(-1) with a mean value of 391 +/- 30 Bq kg(-1) in phosphogypsum samples; while in phosphate wet rock samples, it was found to vary between 621 +/- 9 and 637 +/- 10 Bq kg(-1), with a mean value of 628 +/- 7 Bq kg(-1). The activity concentration of (226)Ra in fertilizer samples (between 31 +/- 4 and 42 +/- 5 Bq kg(-1) with a mean value of 37 +/- 6 Bq kg(-1)) was found to be much smaller than the activity concentration of (226)Ra in phosphogypsum samples (between 302 +/- 8 and 442 +/- 8 Bq kg(-1) with a mean value of 376 +/- 62 Bq kg(-1)). In contrast, the activity concentration of (238)U in fertilizer samples (between 1011 +/- 13 and 1061 +/- 14 Bq kg(-1) with a mean value of 1033 +/- 22 Bq kg(-1)) was found to be much higher than the activity concentration of (238)U in phosphogypsum samples (between 14 +/- 5 and 37 +/- 7 Bq kg(-1) with a mean value of 22 +/- 11 Bq kg(-1)). This indicates that (210)Pb and (226)Ra show similar behaviour, and are concentrated in phosphogypsum piles. In addition, both isotopes enhanced the activity concentration in phosphogypsum piles, while (238)U enhanced the activity concentration in the fertilizer. Due to the radioactivity released from the phosphate rock processing plants into the environment, the highest collective dose commitment for the lungs was found to be 1.02 person nGy t(-1). Lung tissue also shows the highest effect due the presence of (226)Ra in the radioactive cloud (0.087 person nGy t(-1)).  相似文献   

16.
Activity concentrations of the naturally occurring radionuclides like (238)U, (232)Th and (40)K in 400 soil samples collected from four major towns across the northern region of Namibia have been determined using gamma-ray spectrometry with the objective of providing baseline data on the radiation level in the region. The average concentrations of radionuclides in the towns vary from 7.5 +/- 2.3 to 14.2 +/- 3.3 Bq kg(-1) for (238)U, 5.8 +/- 2.6 to 24.9 +/- 6.1 Bq kg(-1) for (232)Th and 52.1 +/- 28.7 to 380.1 +/- 112.9 Bq kg(-1) for (40)K. These concentrations were used to calculate the mean absorbed dose rate and the mean annual effective dose in the region. The low value of 21 +/- 16 microSv obtained for the mean annual effective dose indicates that the region has normal background radiation.  相似文献   

17.
Radionuclides which present in different beach sands are sources of external exposure that contribute to the total radiation exposure of human. In this work, superficial samples of beach sand were collected from the Red Sea coastline (Ras Gharib, Hurghada, Safaga, Qusier and Marsa Alam areas) and at 20 km on Qena-Safaga road. The distribution of natural radionuclides in sand beach samples was studied by gamma spectrometry. The activity concentrations of primordial and artificial radionuclides in samples that are collected from the coastal environment of the Red Sea were 19.2 +/- 3 Bq kg(-1) for (210)Pb, 21.1 +/- 1 Bq kg(-1) for (226)Ra, 22.7 +/- 2 Bq kg(-1) for (238)U, 1.0 +/- 0.1 Bq kg(-1) for (235)U, 11.6 +/- 1 Bq kg(-1) for (228)Ra, 13.0 +/- 1 Bq kg(-1) for (228)Th, 12.4 +/- 1 Bq kg(-1) for (232)Th, 930 +/- 32 Bq kg(-1) for (40)K and 1.2 +/- 0.3 Bq kg(-1) for (137)Cs. The mean external gamma-dose rate was 62.5 +/- 3.2 nSv h(-1), 54.4 +/- 2.8 nGy h(-1) Ra equivalent activity (Ra(eq)) was 107 +/- 5.8 Bq kg(-1), 0.86 +/- 0.04 Bq kg(-1) for representative level index (I(gamma)) and effective dose rate was 0.067 +/- 0.003 mSv y(-1) in beach sand red sea, in air due to naturally occurring radionuclides.  相似文献   

18.
The radioactivity concentrations of (238)U, (232)Th and (40)K in 160 soil samples collected from 16 geographical areas across Windhoek city, Namibia, have been determined using an HPGe detector and found to vary from 15.0 +/- 1.3 to 37.8 +/- 2.1 Bq kg(-1) for (238)U, 17.5 +/- 2.7 to 62.1 +/- 3.3 Bq kg(-1) for (232)Th and 168.9 +/- 15.0 to 784.9 +/- 30.1 Bq kg(-1) for (40)K. These concentrations were used to calculate the mean absorbed dose rate and the mean annual effective dose for the city. The value of 0.07 +/- 0.01 mSv y(-1) obtained for the mean effective dose is less than the maximum permissible dose of 1 mSv y(-1) recommended for the public by the International Commission on Radiological Protection.  相似文献   

19.
A new mass spectrometric method is proposed for measurement of 234U/238U ratio with a single Daly electron multiplier detector using the general peak jump method. The method is based on precise measurement of the 235U/238U ratio and 234U/235U ratio, which are used to calculate the 234U/238U ratio using the equation 234U/238U = 235U/238U x 234U/235U. The results show a significant improvement, i.e., more than 35 times better precision in measuring the (234)U/(238)U ratio with this method (sigma = 2.9 x 10(-8)) as compared to direct measurement of 234U/238U (sigma = 1.1 x 10(-6)). The method widens the applicability of the single collector system, and it will potentially be helpful to improve the precision in the case of the static multicollector system also.  相似文献   

20.
This study was conducted at the request of authorities in western Darfour State, to address the public concern about the levels of radioactivity in the area of Jebel Mun situated at Sudan-Chad international boundaries. It has been identified as a high background radiation area through aerial geological surveys conducted in late 1970s. The ambient gamma dose in the area was measured with the aid of a hand-held dose rate meter (Mini-Rad, Series 1000) and the surface rock samples were collected and analysed for their radioactivity content using a high-resolution gamma spectrometry equipped with HPGe with relative efficiency of 18%. The activity concentrations of 238U, 232Th and 40K were found to range from 39-253 Bq.kg(-1), 41-527 Bq.kg(-1) and 77-3027 Bq.kg(-1), respectively. From the values of the standard deviation it was concluded that the activity concentration of the considered primordial radionuclides was highly scattered (localised) which in turn indicates non-uniformity in the geological features and/or formations. 238U activity concentration corresponds to equivalent mass concentration of 7.77+/-6.12 ppm (3.19-20.73 ppm), which is of no economic importance. Samples are enriched in thorium relative to uranium as reflected by the Th:U mass ratio which ranges from 3 to 17. The absorbed dose rate in air as estimated from the measured activity concentrations of the primordial radionuclides using the DRCFs (dose rate conversion factors) falls within the range of 70-522 nGy.h(-1) with an average of 221+/-130 nGy.h(-1). It corresponds to an annual effective dose equivalent averaged of 0.27 mSv. The regression analysis has shown that the correlation between calculated and the measured ambient dose rate is marginally significant (r2 = 0.59). The 232Th series is the major producer of the surface radioactivity followed by 40K as they contribute 48% and 32% of the total absorbed dose, respectively.  相似文献   

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