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1.
The specific activities of the naturally occurring radionuclides 238U, 232Th, and 40K were measured in rock samples from the Hetaunda area, central Nepal, using gamma spectrometry. The specific activities were found to be in the range of 17–95 Bq kg−1 for 238U, 24–260 Bq kg−1 for 232Th and 32–541 Bq kg−1 for 40K. From these data absorbed dose rates in air and annual effective doses were calculated and compared with respective data from the UNSCEAR compilation. The results from our study open the door to the safe applicability of most of the investigated materials as a cheep building material.  相似文献   

2.
This work presents the results of 137Cs, 40K, 232Th and 238U concentration (Bq kg−1) values in coastal marine sediments collected from 38 sites along the coastline of the island of Margarita, Venezuela. The purpose was to determine baseline values for these radionuclides in surface marine sediments and to detect if there were any anomalously high concentration values. Only three of the 38 sediments analyzed had measurable values above the detection limit of 0.9 Bq kg−1 for 137Cs and the highest only being 1.4 Bq kg−1. While, the concentration (Bq kg−1) ranges for the primordial radionuclides, 40K, 232Th and 238U were as follows: 12.2–211.7, <1.5–9.8 and <4.4–20.7, respectively. These concentration ranges for the primordial radionuclides can be considered as baseline values for surface marine sediments for areas that are considered not polluted by man or contaminated by nature. Finally, the concentration range of 137Cs can also be employed as baseline values, which only seem to have been the result of the atmospheric testing of nuclear weapons in the past.  相似文献   

3.
Radiation dose-risk assessment was carried out for cereal species Brassica compestris var. dichotoma, Oryza sativa var. Shalum1, Zea mays, Lactuca indica, Cumunis sativum, and Clocasia esculanta due to naturally available radionuclides 40K, 238U and 232Th in Domiasiat area. The activity in biota and corresponding soil was measured by precipitation method using NaI(TI) detector. Transfer factor (TF) was for Oryza spp. (1.00E−01-40K, 8.76E−05-232Th, and 9.11E−05-238U), for Brassica spp. (5.39E−01-40K, 8.17E−04-232Th and 2.96E−04-238U) and for Zea spp. (3.41E−01-40K, 5.84E−05-232Th, 8.87E−05-238U) etc., respectively. A detailed physio-morphological study of the biota and extensive investigation of ecosystem was carried out for assessment. The data was modeled using FASSET for dose estimation and obtained total dose was 1.58E−04  \upmu Gy h-1 \upmu \hbox{Gy}\,h^{-1} in Oryza spp., 2.87E−04  \upmu Gy h-1 \upmu \hbox{Gy}\,h^{-1} Brassica spp. and 6.90E−03  \upmu Gy h-1 \upmu \hbox{Gy}\,h^{-1} in Zea spp. etc. The dose was compared with the UNSCEAR dataset for screening level dose for biota. Zea spp. was more susceptible for the chronic radiation exposure.  相似文献   

4.
The naturally occurring radioisotopes such as 238U, 232Th and 40K in the silt samples collected from Moticher lake, Gujarat were evaluated. The activity of 238U, 232Th and 40K was found to be 4.4-9.7 Bq kg−1 with a mean 6.4 ± 1.3 Bq kg−1, 10.5–21.2 Bq kg−1 with a mean 15.6 ± 2.5 Bq kg−1 and 102–231 Bq kg−1 with a mean 160 ± 40 Bq kg−1, respectively. The depth profile study could not reveal any significant vertical correlation on radioactivity levels of 238U, 232Th and 40K. Radium equivalent activity (Raeq), external hazard index (H ex) and internal hazard index (H int) were calculated by using the activity of 238U or 226Ra, 232Th and 40K in silt samples. Annual Effective Dose Equivalent (AEDE) level in Moticher silt was found to be 24.8 ± 5.0 μSv year−1, which is much lower than the worldwide average value. The relative contribution to dose due to 238U and 232Th series were found to be 14% and 53%, followed by the contribution of 33% due to 40K.  相似文献   

5.
In the present study, mussel (Mytilus galloprovincialis, Lamarck, 1819) and sediment samples were collected from the Bosphorus strait and the Golden Horn estuary in 2008 and 2009. Activity concentrations of 137Cs, 40K, 232Th and 238U were measured using a gamma spectrometer equipped with HPGe detector. Sediment samples were separated into <63 μm and >63 μm particle fractions. Analysis of radionuclides was carried out on these two fractions of sediment as well as the soft and shell tissues of mussels. Ranges of radioactivity concentrations in the soft parts of mussels were as follows: 137Cs, 0.86–2.43; 40K: 261.1–496.7; 232Th: 0.49–3.58; and 238U: BDL (below detection limit)-1.38 Bq kg−1 in dry weight. Ranges of radioactivity concentrations in the <63 and >63 sediment fractions were as follows: 137Cs, 8.58–67.92 and 1.12–26.40, 40K, 341.4–683.0 and 281.9–662.2; 232Th, 10.97–20.16 and 7.18–19.18 and 238U, 13.97–27.25 and 6.41–18 Bq kg−1 in dry weight, respectively. The effect of some physical–chemical parameters on the radionuclide accumulation was also examined in the sediment samples. All data in the current study were compared with data in the literature.  相似文献   

6.
The main component of most building materials in Malaysia is rock. All rocks are known to contain natural radionuclides such as 238U and 232Th series as well as 40K. In order to estimate the radiological impact to the dweller, the level of radionuclides present in various building materials available in Malaysia were analyzed using γ-spectrometry. The radiation hazard indexes were calculated based on the above results. The results showed that the activity concentration of natural radionculides 238U, 232Th, 40K was between 19.0–42.2 Bq/kg, 16.5–28.8 Bq/kg and 243.3–614.2 Bq/kg, respectively. On the whole, the radionuclides concentration was still below the global average of 50 Bq/kg, 50 Bq/kg and 500 Bq/kg for 238U, 232Th, and 40K, respectively The radiation hazard indexes of the building materials were also lower than the maximum value suggested.  相似文献   

7.
The activity concentrations of natural radionuclides viz. 232Th, 226Ra and 40K were measured in soil samples of Padubidri on the coastal Karnataka, the site for the proposed coal based thermal power station, using gamma-ray spectrometry to establish a baseline data on radioactivity levels in the environment of the region. The activity concentration of 232Th varies in the range of 38.5–115.5 Bq·kg−1 with a mean value of 66.0 Bq·kg−1, the activity concentration of 226Ra varies in the range 35.3–72.5 Bq·kg−1 with a mean value of 53.5 Bq·kg−1 and that of 40K varies in the range of 307.5–550.9 Bq·kg−1 with a mean value of 419.3 Bq·kg−1. The radium equivalent activity varies in the range of 140.0–242.9 Bq·kg−1 with a mean value of 180.2 Bq·kg−1. The correlation between 226Ra and 40K, 232Th and 40K and 226Ra and 232Th was studied from the results of the concentration of these naturally occurring radionuclides. The calculated dose rates in air due to these naturally occurring radionuclides varies in the range of 66.0–110.0 nGy·h−1 with a mean dose rate of 83.1 nGy·h−1.  相似文献   

8.
A radiation dose assessment exercise was carried out for the Ipomea batata, Allium sativum, Dacaus carota, and Solanum tuberosum due to naturally available radionuclide 40K, 238U and 232Th in the Domiasiat area of Meghalaya. The concentration of radionuclides in biota as well as corresponding soil was measured by precipitation method using NaI detector for continuous 12 months. Transfer factor was calculated and was, for 40K(3.96E−05, 3.40E−05, 3.40E−05, 2.70E−05), for 232Th(3.94E−05, 3.20E−05, 3.20E−054.93E−05), for 238U(3.60E−05, 3.89E−05, 3.85E−054.57E−05), respectively in each biota due to each radionuclide. The point source dose distribution (source ↔ target) hypotheses was applied for the consideration of absorbed fraction. The generated data were modeled using the FASSET method and obtained dose was 8.42E−03, 8.36E−03, 7.78E−03, 7.74E−03 μGy h−1, respectively and finally compared with the IAEA and UNSCEAR dataset for screening level dose for terrestrial biota.  相似文献   

9.
In this work, the radionuclide activity concentrations of 226Ra, 232Th and 40K in surface soils and radon levels in dwellings of Karabük, Turkey were determined in order to evaluate the environmental radioactivity. Concentrations of 226Ra, 232Th and 40K radionuclides were determined using gamma spectrometry with using HPGe detector. The etch track detectors (CR-39) were used to determine the distribution of radon concentrations. The average activity concentrations for 226Ra, 232Th and 40K were found as 21.0, 23.5 and 363.5 Bq kg−1, respectively. The calculated average annual effective dose equivalent from the outdoor terrestrial gamma radiation from 226Ra, 232Th and 40K is 53.5 μSv y−1. The average radon concentration and annual effective dose equivalent of 222Rn in Karabük dwellings were obtained 131.6 Bqm−3 and 3.32 mSv y−1, respectively. The evaluated data were compared with the data obtained from different countries.  相似文献   

10.
The activity concentration and absorbed gamma dose rates due to primordial radionuclides (238U, 232Th and 40K) have been determined for the soil of Coimbatore city using NaI(Tl) gamma-ray spectrometer. The average activity concentrations of 232Th, 238U and 40K in the soil samples have been found to be 31.4 Bq·kg−1, 12.8 Bq·kg−1 and 698.0 Bq·kg−1, respectively, which give the total gamma dose rate contribution of 56.4 nGy·h−1. Grab sampling technique has been used to determine the indoor radon (222Rn) and thoron (220Rn) progeny levels in different dwellings in the city. The concentrations of radon and thoron progenies range from 0.4 to 10.4 and from 0.7 to 12.7 mWL with a mean value of 1.4 mWL and 3.1 mWL, respectively. The annual effective dose due to radon and thoron progeny has been found to be 0.14 mSv·y−1.  相似文献   

11.
In this study the concentration of natural radionuclides has been investigated in soil and water of Karun river by using a high resolution (HPGe detector, n-type) γ-spectrometry. The concentrations range in water sample was 47.6 ± 5.6–130.8 ± 6.3, 0.0–23.4 ± 0.5 and 0–6.4 ± 2.0 Bq L−1 for 40K, 232Th and 226Ra respectively. For soil samples the concentration range of 275.7 ± 8.6–458.6 ± 6.8, 19.2 ± 5.35–41.1 ± 3.95 and 29.9 ± 1.53–50 ± 1.54 Bq kg−1 was obtained respectively for 40K, 232Th and 238U. 137Cs was also detected in some part of the region in soil samples. The mean concentration of 137Cs was 5.5 ± 0.6 Bq kg−1. The origin of this activity is unknown. The average absorbed dose rate in outdoor air at a height of 1 m above the ground was found to be 54.3 ± 3.7 nGy h−1. The results of this study indicate that the area has standard background radiation level.  相似文献   

12.
The activity concentrations of 40K, 232Th, and 238U in the characteristic rocks of the Modane-Aussois region (Western Alps, France) were determined using an HPGe gamma-ray spectrometry system. The activity concentrations of 40K varied from 18 Bqkg−1 (limestone dolomite) to 392 Bqkg−1 (calcschist), while those of 232Th varied from 0.7 Bqkg−1 (limestone dolomite) to 18 Bqkg−1 (calcschist). The activities associated with 238U ranged from 9 (quartzite) to 29 Bqkg−1 (dolomite). In the investigated rock samples, concentrations of 238U (ppm) and 40K (%) had a strong negative correlation.  相似文献   

13.
This study was conducted to determine the concentration of natural radionuclides in the granite rocks of selected quarry sites in Johor state, Malaysia and their possible radiological effects. The activity concentrations of 238U, 232Th and 40K in the areas of study indicated varying values of 238U, 232Th and 40K. The highest values of 238U and 232Th concentrations (67±1 and 85±2 Bq kg?1, respectively) were observed at Kamad Quarry (IJM), whereas the highest value of 40K concentration (722±18 Bq kg?1) was detected in Kim Seng Quarry, while the values of activity concentration are lower in Hanson Quarry Products (Kulai) (25±0.5 for 238U, 24±0.5 for 232Th and 429±11 for 40K). Overall, 40K has the highest concentration in the granite rocks of the quarry sites, followed by 232Th and the least for 238U. The radium equivalent activity concentration was found in the range between 94 and 239 Bq kg?1, the absorbed dose rate was found to be in the range between 47 and 112 nGy h?1, and effective dose ranged from 58 to 137 μSv h?1. Moreover, the internal and external hazard index values were given in results lower than unity.  相似文献   

14.
The contents of natural radionuclides in various types of sedimentary rocks in Um Bogma Formation and base of El Hashash Formation were determined by gamma-ray spectrometry. Three types of lower Carboniferous sedimentary rocks were investigated; sandstone (El Hashash Formation), dolostone and argillaceous sediments (Um Bogma Formation). The alteration processes are dolomitization, dedolomitization, karstification and lateritization. The specific radioactivity of 238U, 226Ra, 232Th and 40K determined in different samples, indicate that 238U and its decay products contribute primarily to the high natural radioactivity of rocks. The maximum concentration of 238U reached up to 2129.36 ppm in argillaceous sediments. The average concentrations of determined radionuclides (238U, 226Ra, 232Th and 40K) are 8.34 ppm, 7.88 ppm, 4.68 ppm and 0.3%, respectively in sandstone. In dolostones the average concentrations are 418.69 ppm, 808.75 ppm, 3.14 ppm and 0.29%, respectively. For argillaceous sediments are 276.88 ppm, 419.49 ppm, 11.47 ppm and 0.93%, respectively. The 238U/226Ra ratio in sandstone ranges between 0.89 and 1.25, while in dolostones and argillaceous sediments are 0.27–2.63 and 0.27–1.83, respectively. These variations in the concentrations of radioelements and their ratios are due to the action of the alteration processes affected these different sedimentary rocks in different times. Environmentally, the Raeq in dolostones and argillaceous sediments exceeds the permitted limits, while in the sandstone samples; it is within the permissible levels.  相似文献   

15.
The study aims to evaluate the activity concentrations of 238U, 232Th, 40K and 137Cs along Rosetta beach, Egypt. Non-destructive assay techniques were carried out using HP-Ge spectrometer and binocular microscope. The results of this study serve as a database for radioactivity levels of the mineral sand deposits of Rosetta area. The activity concentrations of 238U, 232Th and 40K ranged from 5.39 to 134.2, 6.6 to 160.8 and 57.6 to 492 Bqkg−1 respectively. The range of activity concentrations of 137Cs is between 0.05 and 0.91 Bqkg−1. The total gamma absorbed dose rates varied from 11.59 to 160.01 nGyh−1 with a mean value of 50.53 nGyh−1. These values correspond to an annual effective dose equivalent of 0.01–0.2 mSvy−1 with a mean of 0.07 mSvy−1, which is in agreement with the worldwide average. Also, a correlation between the calculated zircon and monazite radioactive mineral contents with the measured radioactive isotopes was carried out to determine the contribution of each mineral for radioactivity. These correlations predicted that both zircon and monazite minerals are the main contributors for radioactivity in the Egyptian beach black sands. Also the present study ensured that area under investigation is to be safe for public.  相似文献   

16.
The uptake of 238U and 232Th in different parts of some selected plants used in traditional treatment of hypertension and diabetes in south-eastern Morocco (Errachidia area) has been studied using two different types of solid state nuclear track detectors (SSNTDs) LR-115 type II and CR-39. Plant uptake of radionuclides is one of many vectors for introduction of contaminants into the human food chain. Thus, it is critical to understand soil–plant relationships that control nuclide bioavailability. Soil concentrations of uranium ranged from 6.10 to 11.62 ppm, with a mean of 7.90 ppm. Soil concentrations of thorium ranged from 2.70 to 4.80 ppm, with a mean of 3.41 ppm. Mean uranium specific activities were 8.38 Bq kg−1 in root tissue, 5 Bq kg−1 in stem tissue and 6.02 Bq kg−1 in leaf tissue. Mean thorium specific activities were 2.53 Bq kg−1 in root tissue, 1.64 Bq kg−1 in stem tissue and 1.96 Bq kg−1 in leaf tissue. The transfer factors of 238U and 232Th from soil to different parts (root, stem, leaf, seed and fruit) of studied plant samples have been investigated. The transfer factors obtained for root plants were markedly higher than those for leaf, stem, fruit and seed plants. Soil-to-plant transfer factor (TF) is one of the most important parameters to be used in transfer models for predicting the concentration of radionuclides in agricultural crops and for estimating dose impacts to man. This study of uranium and thorium uptake in plants used in traditional medicine is also significant as far as the health hazard effects of uranium and thorium in human being are concerned.  相似文献   

17.
Loess sediment was prepared and characterized with well-established K, Th and U contents, and corresponding 40K, 232Th and 235,238U activities, intended for use as a reference material in the annual radiation dose determination for luminescence dating. To this purpose, loess was collected in Volkegem, Belgium, and — after drying, pulverizing and homogenizing — characterized via k 0-INAA and HPGe gamma-ray spectrometry. This led to 12 kg material with a grain size below 50 μm, with established K, Th and U homogeneity, with the 232Th and 238U decay series proven to be in equilibrium, and with the following K, Th and U reference data: K = 16.5±1.5 g·kg−1 (40K = 497±45 Bq·kg−1); Th = 10.4±0.6 mg·kg−1 (232Th = 42.2±2.5 Bq·kg−1); U = 2.79±0.12 mg·kg−1 (238U = 34.5±1.5 Bq·kg−1; 235U = 1.59±0.09 Bq·kg−1; 235+238U = 36.1±1.7 Bq·kg−1). These data were confirmed via comparison with the results from NaI(Tl) field gamma-ray spectrometry, thick-source ZnS alpha-counting and thick-source GM beta-counting (after converting all data to Gy·ka−1). The reference material is available (as aliquots up to 200 g) from the Ghent Luminescence Laboratory to all interested luminescence dating laboratories upon motivated request.  相似文献   

18.
The present work investigated the activity concentrations of natural radionuclides 226Ra, 232Th and 40K in beach sand samples along coastal Kerala including high background radiation area. The activity of 232Th ranges from below detectable level to 23029.9 Bq kg−1 with a mean value of 2660.2 Bq kg−1 for 0–10 cm depth interval. For 10–20 cm depth, the 232Th activity ranged from below detectable to 4452.2 Bq kg−1 with a mean value of 815.5 Bq kg−1. The variation of 226Ra activity with depth is parallel with the 232Th activity distribution in beach sand. Its activity varied from below detectable to 5169.5 Bq kg−1 with a mean value 487.6 Bq kg−1 at 0–10 cm depth. For 10–20 cm depth interval, the 226Ra activity ranges from below detectable to 1823.6 Bq kg−1 with a mean value 296.0 Bq kg−1. Similarly the activity varies from below detectable to 1826.6 Bq kg−1 with a mean value of 211.0 Bq kg−1 for a depth interval of 20–30 cm. The activity of 40K at different depth is also discussed. Statistical analysis of radioactivity was also carried out. The results of these investigations are presented in this paper.  相似文献   

19.
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   

20.
A survey was carried out to determine terrestrial gammaradiation dose rates, the concentration level of 238U and 232Th and α and β activities for the surface soil in Ulu Tiram, Malaysia A 125 measurements were performed using a NaI(T1) gamma-ray detector with crystal size of 1″ × 1″ on 15 soil samples collected from the site area about 102 km2 238U and 232Th concentrations were determined in soils by using hyper pure germanium (HPGe) gamma-ray spectrometry. The activity of α and β from the surface soil was counted by using alpha beta counting system. The average value of 238U and 232Th concentrations in soil samples collected are 3.63±0.39 ppm within the range of 1.74±0.20 to 4.58±0.48 and 43.00±2.31 ppm within the range of 10.68±0.76 to 82 10±4.01 ppm, respectively. The average estimate of α and β activity in soil samples collected are 0.65±0.09 Bqg−1 and 0.68±0.08 Bqg−1, respectively. The average of terrestrial gamma-radiation dose rates measured in Ulu Tiram was found to be 200 nGy h−1, within the range of 96 to 409 nGy h−1. The population weighted outdoor annual effective dose was 1.2 mSv.  相似文献   

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