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1.
The results of investigations of the level of contamination by γ-radioactive isotopes of lichens fromParmeliaceae family, collected in the years 1949–1996 are presented. The most important isotope, occurring in significant amount was137Cs. From the natural isotope group also40K,226Ra,210Pb,234Th and214Bi were found in few samples. Starting from 1956, the137Cs isotope is detected in all collected samples with two distinct maxima in 1963 and 1989. Taking into accunt the age of the collected lichens, their activity and the level of the radioactivity fall-out, the full correlation of the obtained results with the amount of the radioactive fall-out is observed.  相似文献   

2.
The aim of this work was to determine 137Cs and 40K radioactivities in soil samples taken from the Babia Góra National Park (BPN) in south Poland. The cluster analysis (CA) and principal component analysis (PCA) were used to discuss the obtained data. 10 cm thick soil cores were collected from the BPN area. Each sample was divided into three sub-samples. The samples were dried, homogenized and packed in polyethylene containers. The radioactivities of 137Cs and 40K were measured by means of gamma spectrometry. It was found that 137Cs radioactivity in the whole 10 cm soil cores was in the range from 1,916 to 28,551 Bq m?2. The radioactivity of 40K varied from 1,642 to 25,654 Bq m?2. Using CA it was possible to diverse the soils taking into account soil types. By use of the PCA method, it was chosen three factors which are appropriate to characterize researched parameters.  相似文献   

3.

This study evaluated the correlation between radioactivity concentrations and soil properties, and determined the total annual effective dose near an underground geologic repository for transuranic wastes. Soil samples were collected from two historical monitoring areas (Near Field and Cactus Flats). Alpha-particle spectrometry was used for the analysis of 241Am, 239+240Pu and 238U, while 137Cs, 40K, 232Th and 226Ra were detected by gamma ray spectrometry. Higher radioactivity concentrations and stronger positive correlations between radioactivity concentrations and soil properties were obtained in Cactus Flats compared to Near Field. The total annual effective dose was lower than the recommended limit of 1 mSv y??1.

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4.
Various types of soil samples were collected in the southern part of Brazil, with depth intervals of 5 cm, down to 50 cm, using a specially designed sampler. Pedological analysis of these soils were performed. Nuclear activities of137Cs (expressed in Bq m–2) and radioactive natural element (226Ra,228Ra and40K) concentrations were determined by low background gamma-ray spectrometry.137Cs concentrations were correlated with radioactive natural element concentrations and pedological, climatological and geographic parameters related to the soil samples collected.  相似文献   

5.
This paper presents the results of measurement of natural and fallout radioactivity in soil samples of Chamba and Dharamshala areas in Himachal Pradesh, India. Spatial distribution of 238U, 226Ra, 232Th, 40K, 137Cs was determined using High resolution gamma-ray spectrometry. The mean activity concentration in Chamba region due to 238U, 232Th, 40K and 137Cs was 32.3, 58.4, 588.3, and 10.9 Bq kg−1, respectively, whereas in Dharamshala it was 35.7, 61.3, 594.9, 10.0 Bq kg−1, respectively. Absorbed gamma dose rate (D) in air was calculated using appropriate dose conversion factors, which was varying from 45 to 103 nGy h−1. To control the radiation exposure due to natural radioactivity in soil, if it is used as building materials, radium equivalent activity (Raeq) and activity index were also evaluated. Radium equivalent activity calculated for the soil ranged from 95.5 to 234.2 Bq kg−1 with average of 171.0 Bq kg−1.The calculated Activity concentration index was ranged from 0.34 to 0.85 with an average value of 0.64. The natural and fallout radioactivity in soil of this region is comparable with Indian average and other parts of the world. The percentage contribution of 238U, 232Th and 40K and 137Cs to the average external gamma dose rate was 22, 46, 32, 2%, respectively. This shows that the dose contribution due to fallout radioactivity is negligible as compared to the natural radioactivity.  相似文献   

6.
The 137Cs activity concentration in the surface air between 1977 and 2007 was decreasing with an ecological half-life of 3.4?years, however, during 2007?C2010 the yearly averaged 137Cs activity concentrations were almost constant. The increased atmospheric 137Cs and 40K levels observed during the winter may be due to surface soil resuspension and radionuclide transport by winds, particularly from open agricultural areas, as confirmed by high correlation coefficient between 137Cs and 40K atmospheric levels (R?=?0.84), and similar 137Cs/40K activity ratios in aerosols (0.07) and soils (0.05).  相似文献   

7.
The paper presents the results of high resolution gamma-spectrometric measurements of 137Cs, 40K, 232Th and 238U in Indian soils collected from 24 different places from normal natural radiation background areas. The depth profile of 137Cs was studied at sampling sites. The paper also presents 137Cs levels in top soil at Mumbai during 1986 to 2000. The results in Mumbai soil indicate clearly the accumulation from fallout only on the top soil and seasonal peaking during the beginning of the monsoon season.  相似文献   

8.
After the Chernobyl accident in 1986, Mexico imported from an European country 28,000 tons of contaminated powder milk with the fission product 137Cs. When the contamination was detected, the alarm among the authorities and population spread out very quickly and of course the product was retired at once from the foodstuff market. Nevertheless, the public panic grew up in such a manner, that even the way to manage and to dispose safely this material, considered highly dangerous, was largely discussed. Now, about two decades ago from this event, a study has been performed to compare the level of radioactivity due to both radioisotopes present in one saved sample: the artificial contaminant 137Cs, beside the natural, all around present 40K, in order to evaluate in a more realistic way how risky was the management, possible consumption, and final disposition of this nourishment. This paper considers results obtained within an uncertainty degree equal to ±5%, and set up conclusions by comparing artificial and natural radioactivity present in that contaminated powder milk.  相似文献   

9.
A variety of wild mushrooms were collected in a forest on the Noto Peninsula, Japan, to determine the concentration of 137Cs and 40K. The wild mushroom species belong to the orders Agaricales and Aphyllophorales. The concentration of 137Cs varied widely (1.4–4,100 Bq/kg dry weight) in mushrooms growing in soil. On the contrary, 137Cs concentration levels were relatively low (1.9–20 Bq/kg-dry weight) in mushrooms growing on wood. The concentration of 40K varied widely (12–2,400 Bq/kg-dry weight) in contrast with several previous reports that suggest relatively constant 40K levels in mushrooms. Unusually low concentrations of 40K were observed in a few mushroom species that had very hard fruiting bodies with peculiar shapes. The mean and median of 137Cs concentration in the present study were similar to those previously reported for Japanese mushrooms. Among the Agaricales mushrooms, Entolomataceae and Tricholomataceae families growing in soil had the highest concentration of 137Cs. Among the Aphyllophorales mushrooms, Gomphaceae and Ramariaceae families growing in soil also had the highest 137Cs concentrations. The concentrations of 137Cs and stable Cs in mushroom samples were positively correlated. The concentration ratio of 137Cs/Cs differed between Agaricales and Aphyllophorales mushrooms. The average 137Cs/Cs ratio in mushrooms growing in soil was similar to that calculated for the top soil (<5 cm deep) alone because the mycelia of the mushrooms were mainly distributed near the surface of the soil.  相似文献   

10.
A horizontal transport of radionuclides was studied by the analysis of the radioactivity of the surface soil samples from valleys of Wieprz river and its bottom sediments. Natural gamma-isotopes (40K, 238U and 232Th series) antropogenic (134Cs and 137Cs) and alpha-isotopes 238Pu and 239,240Pu were measured. The different kind of bed rock and terrain configuration, influenced the radionuclide transportation from the soil to river bottom sediments. Radioactivity of the sediment samples is definitely lower than the soils. Very strong adsorption of isotopes in soil hinders their horizontal migration. Calculated 238Pu/239,240Pu ratio is characteristic for global fallout and about 90% of the 137Cs comes from Chernobyl.  相似文献   

11.
On the Stabatishke site near to Ignalina Nuclear Power Plant a near surface repository for low and intermediate-level short-lived radioactive waste is being constructed to store the waste which was produced during the decommissioning of the Ignalina Nuclear Power Plant. A possible spread of radionuclides from the near surface repository and the radiation level of expression are one at the most important aspects while evaluating the safety of the repository. The article examines the specific activity of artificial (137Cs, 90Sr) and natural (226Ra, 232Th, 40K) radionuclides in the soil of Stabatishke site of Ignalina NPP in pinewood; the spread of these radionuclides is determined in the system “soil-tree”. The change of long term soil pollution with artificial radionuclides was estimated. This is a background soil pollution which had been there before the exploitation of the near surface waste repository. The transfer factors of natural (226Ra, 232Th, 40K) and artificial (137Cs, 90Sr) radionuclides from the 0-to-20-cm soil layer to different annual pinewood rings were measured. After estimation of the position of pine roots in accordance to the soil vertical and the annual change of the plant biomass, the transfer factor of 137Cs movement to different annual pinewood rings from the separate 0 to 20-cm soil layers was determined.  相似文献   

12.
Competitive biosorption of thorium and uranium by Micrococcus luteus   总被引:2,自引:0,他引:2  
Lichens, sampled around Chernobyl in 1990 and in Slovenia in 1992, were analyzed for radionuclides and elements, including Cs. Data were processed by Monte Carlo aided Target Transformation Factor (MCTTFA). The resulting factors indicate environmental accumulation routes. 40K : K and 210Pb : Pb ratios tested the procedure, showing fully mixed 40K and K, while for 210Pb and Pb the expected variability in specific radioactivity was confirmed. 137Cs showed a large factor-specific variability in 137Cs : Cs ratios. For the 1990 data, MCTTFA singled-out 137Cs in a separate factor, suggesting that the overall behavior of 137Cs cannot be derived from that of Cs: source (route)-related specific radioactivity makes that all individual transport-components should be taken into account.  相似文献   

13.
The distribution of the anthropogenic (134Cs and 137Cs) and natural (238U, 232Th and 40K) radionuclide concentrations were studied in soil, foodstuff and bioindicator samples collected from the near site of the Medzamor Nuclear Power Plant at the border of eastern Anatolia of Turkey. For some time, the gross-a and b-concentrations were also determined in the water samples of the region and the absorbed dose rates in air at 1 m above ground were measured. The results showed no additional artificial contamination from the Medzamor Nuclear Power Plant before June 1996.  相似文献   

14.
The concentration of naturally occurring40K and137Cs from fallout were determined in various mushrooms as well as in a few samples of forest soil from the same region over the period of 1984–1988. The137Cs content in mushrooms before the reactor accident at Chernobyl was generally below 500 Bq kg−1 dry matter, except Paxillus involutus /2700 Bq kg−1/. A remarkable increase of the137Cs activity /up to ten times/ was observed in 1986. For almost all examined species this activity remained basically at the same level for the next two years. No correlation between40K and137Cs in mushrooms has been found.  相似文献   

15.
The soil-to-grass transfer factors and grass-to-milk transfer coefficients were determined for 137Cs and stable Cs in soil, grass and milk samples collected in Aomori Prefecture, Japan. The concentrations of 137Cs in the soil and grass samples collected from 25 sampling sites were 13±12 Bq.kg-1 and 2.0±2.1 Bq.kg-1 dry wt., respectively. The geometric mean of soil-to-grass transfer factor of 137Cs was 0.13 and its 95% confidence interval was 0.017-0.98. The transfer factor of 137Cs was higher than that of stable Cs, and they had a positive correlation. The concentration of K in the soil affected both transfer factors. The concentration of 137Cs in milk samples collected from 16 sites was 76±43 mBq.kg-1 fresh wt. and had a good correlation with that of stable Cs. The geometric mean of grass-to-milk transfer coefficient of 137Cs was 0.0027, assuming that a cow's total daily intake was 20 kg of dry grass. The transfer coefficient of 137Cs was positively correlated with that of stable Cs.  相似文献   

16.
The distribution and origin of natural 40K,226Ra and228Ra and artificial 137Cs have been investigated in the surface soil of a West Macedonia basin at four lignite fired power plants. No significant increase in specific activity of soil due to natural radionuclides of coal has been found. The specific activities of 226Ra, 228Ra and 40K are equal to those of Greek soils. Radiocesium activity is slightly higher in the first 10 cm layer. The application of chemometrical methods confirmed that the radionulides 226Ra, 228Ra and 40K are natural components of the soil and they do not originate from fly ash. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

17.
Water, plant and soil samples from forested area were analyzed in order to study the behavior of radionuclides in the forest ecosystem. The concentration of 137Cs in the soil decreased with depth, while stable Cs and 40K were almost constant. It is suggested that most of the 137Cs once entered in the forest ecosystem is trapped in the upper part of the soil.  相似文献   

18.

The mineral extraction activities may disturb the natural radioactivity, therefore current study aims to generate baseline data of natural radionuclides and anthropogenic 137Cs before the start of industrial activities. Gamma spectrometry and gross alpha and beta counting systems were used for activity measurement in environmental samples. In soil, the mean activity of 232Th, 226Ra, 40K and 137Cs were determined as 79 (66–117), 47 (34–80), 823 (602–1159) and 1.3 (1.1–4.5) Bq kg?1, respectively. The average annual effective dose rate (128.7 µSv h?1) in the study area was twice higher than world’s average value. Indoor hazard index was greater than unity at two places; therefore, proper ventilation is proposed during construction.

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19.
Field measurements of radioactivity were performed in highly contaminated areas around Chernobyl in the summer of 1990. Six radionuclides including the most dominant137Cs have been identified in soil samples through -ray spectrometry. The relation between the -ray dose rate above the ground and the radioactivity density in soils has been investigated. The external dose from deposited radiocesium for the period of 70 years after the deposition has been evaluated to be about 5 mSv per 1 and 0.5 Ci km–2 of137Cs and134Cs deposition, respectively.  相似文献   

20.
Four radionuclides ( 137Cs, 238U, 232Th and 40K) have been analysed in soil samples collected from Aramoko-Ekiti, South West Nigeria by a sensitive gamma-ray spectroscopic system consisting of a 7.6 cm × 7.6 cm Nal(TI) scintillation detector interfaced with Canberra series 10 plus multichannel analyser. Results obtained show that the radionuclides are present in varying concentrations in the soil, except 137Cs which was not detectable. The absorbed dose rates in the air of the location due to these radionuclides is within the UNSCEAR recommended world average value.  相似文献   

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