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1.
Surface sediment samples were collected at the West (east coast and west coast of Peninsular Malaysia) and East (Sabah and Sarawak) Malaysia in several expeditions within August 2003 until June 2008 for determining the level of natural radium isotopes. Activity concentrations of 226Ra and 228Ra in surface marine sediment at 176 sampling stations were measured. The activity concentrations of both radionuclides in Malaysia (East and West Malaysia) display varied with the range from 9 to 158 Bq/kg dry wt. and 13 to 104 Bq/kg dry wt., respectively. Meanwhile, the ratio distributions of 228Ra/226Ra were ranged from 0.62 to 3.75. This indicated that the ratios were slightly high at west coast of Peninsular Malaysia compared to other regions (east coast of Peninsular Malaysia, Sabah and Sarawak). The variation of activity concentrations of 226Ra and 228Ra and its ratios were also supported by the statistical analyses of one-way ANOVA and t test at 95 % confidence level, whereby there were proved that the measured values were different between the regions. These different were strictly related to their half-life, potential input sources (included their parents, 238U and 232Th), parent’s characteristic, the geological setting/formation of the study area, environment origin and behavior.  相似文献   

2.
The present occurrence of 226Ra and 228Ra in marine sediment core and fish from the Exclusive Economic Zone in the east coast of Peninsular Malaysia were studied. Sediment core and biota in respectively was collected using multicorer device and purchased from local fishermen at identified stations during the cruise expedition conducted in 2008. The purpose of this study was to determine and to make available an inventory of activity concentration levels and activity ratio for these radionuclides in this region. The activity concentrations of 226Ra and 228Ra in sediment core and edible part of fish were ranged between 15.9–46.5 and 27.7–87.1 Bq/kg dry wt and; 0.80–2.13 and <0.95–3.57 Bq/kg fresh wt, respectively. Meanwhile, the activity ratios of 228Ra/226Ra in sediment core and fish were varied with the range between 1.63–2.09 and 0.45–2.38, respectively. Refer to those ranges the activity concentrations of radium isotopes were comparable with other region. Thus, it can be concluded that the occurrence of radium isotopes mainly supplied from terrestrial sources and the factors of assimilation efficiency and transfer coefficient of radium may probably effect to the variation activity concentration of 226Ra and 228Ra and its activity ratio in edible part of pelagic and demersal fish obtained in this study.  相似文献   

3.
An investigation on the distribution of radium activity levels in the entire south eastern coast of Tamil Nadu, India, from Chennai to Kanyakumari was carried out. Insitu preconcentration technique was adopted by passing 1,000?L of seawater through MnO2 impregnated cartridge filters at all the locations. In the coastal waters, 226Ra and 228Ra concentration was observed to be in the range of 1 to 1.81 and 3.1 to 7.5?mBq/L, respectively with an average of 1.52 and 4.53?mBq/L. respectively, while the sediment samples showed 226Ra activity levels from 8.1 to 129.0?Bq/kg and 228Ra varied from 14.7 to 430.01?Bq/kg. The Kd values for 226Ra was observed to be from 5.3E03 to 3.5E05?L/kg and for 228Ra it was in the range of 2.3E03 to 5.9E04. It was observed that the concentration of 228Ra was more than 226Ra in all the locations. The spatial distribution of the activity with respect to location is discussed in the paper. The radioactive database obtained, represents reference values for coastal environment of Tamil Nadu.  相似文献   

4.
The radioactivity levels of Istanbul environs lignites were determined. The gamma-spectrometric technique has been used for the determination of activity levels of naturally occurring radionuclides 235+238U, 228+232Th, 40K, 226Ra and fallout radionuclides 137Cs in lignites taken from 7 different parts of Istanbul. Concentration of 238U, 228+232Th, 40K, 226Ra 137Cs and 235U were found up to 1.6 ppm, 1.7 ppm, 4.9 ppm, 56.8 Bq/kg, 34 Bq/kg, 1.8 Bq/kg, 1.6 Bq/kg, respectively. In addition total alpha- and beta-activity levels in lignite samples were found to be 7.6 and 15 eps, respectively.  相似文献   

5.
Study for distribution of Naturally Occurring Radioactive Materials (NORM) i.e. 226Ra, 228Ra and 40K in the east coast of Peninsular Malaysia Exclusive Economic Zone (EEZ) was carried out as part of the national marine environment project. Sixteen marine sediment cores from selected locations within the EEZ were collected for determination of NORM activity concentrations using high-purity germanium (HPGe) gamma spectrometer. From the measurement, the activity concentration of 226Ra, 228Ra and 40K is ranged from 16 ± 4 Bq/kg to 46 ± 6 Bq/kg (total mean 30), 28 ± 7 Bq/kg to 87 ± 11 Bq/kg (total mean 56) and 171 ± 33 Bq/kg to 690 ± 89 Bq/kg (total mean 420), dry wt., respectively. The activity concentrations of radionuclides in most of the core were quite uniform suggesting that there were thorough vertical mixed of sediment throughout the core. The results obtained were also in good agreement with those previous reported from other countries in the region and therefore can be used to enhance present radioactivity database. The calculated external hazard values were ranged from 0.25 to 0.51 with the mean of 0.38 (less than unity) showed little risk of external hazard to the workers handling the sediments and it was likely low level of the mainland natural gamma-radiation in the east coast of Peninsular Malaysia.  相似文献   

6.
An investigation on the distribution of 226Ra and 228Ra activity concentration in coastal surface sea water from Okha in Gujarat to Ratnagiri in Maharashtra state along the west coast of India was carried out. In-situ pre-concentration technique was used to measure radium isotopes by passing 1,000 L of seawater through MnO2 impregnated polypropylene filter cartridges at all the locations. 226Ra was estimated using gamma ray peak of its daughter radionuclides 214Bi and 214Pb. 228Ra was estimated from its daughter 228Ac. In the coastal waters, 226Ra and 228Ra activity concentration were observed to be in the range of 1.5–2.9 and 2.5–8.6 Bq m?3 with a mean of 2.2 and 4.9 Bq m?3 respectively. The activity of 228Ra was observed to be more than 226Ra in all the locations. The variation in spatial distribution of the radium isotopes activity concentration and its ratio with respect to location is discussed in the paper. The radioactive database obtained represents reference values for coastal environment of India.  相似文献   

7.
A procedure for the analysis of228Ra in drinking water has been developed. The procedure involves separation of radium by an initial coprecipitation with lead sulfate. The isolated Pb(Ra)SO4 is then dissolved in sodium diethylenetriamine pentaacetate (DTPA). Radium-228 is co-precipitated from this solution with barium sulfate while the DTPA supernate which contains pre-existing228Ac is discarded. The purified Ba(Ra)SO4 precipitate is then allowed to ingrow, generating228Ac, which is then dissolved in DTPA, isolating both226Ra and228Ra in the precipitate while228 Ac remains in the aqueous supernate. The supernate is partitioned against di-(2-ethylhexyl phosphoric acid), HDEHP, dissolved in n-heptane, which retains the228Ac. Actinium-228 is then stripped from the organic phase by partitioning against 1M HNO3. Finally, the228Ac is coprecipitated onto cerium oxalate. The precipitate is collected on a filter and counted in a low-background beta counter. Radium-228 standards with concentrations ranging from 0.044 to 1.6 Bq were used to establish the detector counting efficiency for228Ac in cerium oxalate samples, as well as monitoring the chemical yield and absorption factors. The resultant average value of 30.3±2.1 cpm/Bq (uncertainty given at 95% level of confidence) was obtained. Various228Ra cross checks from U. S. Environmental Protection Agency (EPA) with concentrations of 0.063–0.52 Bq/l were analyzed in order to assess the performance of the procedure. The minimum detectable concentration (MDC) of228Ra in water with this procedure is 0.015 Bq/l. This is based on a one liter aliquot of sample, a 100 min couting period, and a 3 hour decay interval between the end of228Ac ingrowth and midpoint of counting. Decontamination factor studies were performed to determine the extent of the carry-over of238U,226Ra,210Po, and90Sr into the final fraction.  相似文献   

8.
Specific activity of natural radionuclides; 226Ra, 232Th and 40K were measured in the agricultural soil of eastern salt range of Pakistan using gamma ray spectrometry. The soil samples were collected within the ploughing region (up to 12 cm depth) and processed before analysis. The average specific activities of different radionuclides in the dry mass of soil samples were: 40K, (666 Bq/kg), 226Ra (51 Bq/kg), and 232Th (59 Bq/kg). The average outdoor terrestrial absorbed dose rate in air from gamma radiation one meter above ground surface was found to be 93 nGy/h.  相似文献   

9.
The concentrations of radium isotopes and the progenies (226Ra; 228Ra and 228Th) in three hokutolite samples from Tamagawa hot-spring were measured. These isotopes were analyzed by a well-type HPGe γ-ray spectrometer for the 351, 911 and 583 keV γ-ray from 214Pb, 228Ac and 208Tl, respectively, each being in radioactive equilibrium with precursors. Concentration of 226Ra and 228Ra were observed to be in the range of 52–85 and 7.1–85 Bq/g, respectively. The activity ratios of 228Ra/226Ra and 228Th/226Ra provided the estimation of the growth rate (0.09–0.15 mm/y). Estimated 228Ra/226Ra activity ratios in hot-spring water from surface of three hokutolite were concordant.  相似文献   

10.
Knowledge of radioactivity levels in human diet is of particular concern for the estimation of possible radiological hazards to human health. However, very few surveys of radioactivity in food have been conducted in Ghana. The natural radionuclides 226Ra, 228Ra, 228Th and 40K were measured in the foodstuffs using gamma ray spectrometry. All samples were found to contain high 40K content in the range 87.77?C368.50?Bq?kg?1. The maximum concentration of 228Th and 40K were found in cassava to be 14.93?±?3.86 and 368.50?±?19.20?Bq?kg?1, respectively. The total annual committed effective dose was estimated to be 4.64?mSv. The daily intake of radionuclides from food consumption reveals that cassava and plantain are the highest contributors, while millet is the lowest. The daily radionuclide intake from the foodstuffs consumed by the general public was 411.32?Bq and the daily internal dose resulting from ingestion of the radionuclides in the foodstuffs was 0.01?mSv. The radionuclide concentrations were comparable with those reported from other countries.  相似文献   

11.
Tritium and 14C concentration in hot spring water in Korea were determined. Tritium in the most hot spring samples could not detected and concentration range was <0.5?C1.31?TU. And 14C contents were ranged 1.7?C78.6?pMC. From the 3H and 14C analysis, we found some hot springs are mixed with recent groundwater and hot spring water ages were estimated from 1,940 to 32,800?years. And also, 226Ra and 228Ra were determined simultaneously in hot spring water, and some other radionuclides were also analyzed. Content distribution of 222Rn was 50?C3,760?pCi/L, 226Ra was <0.003?C0.15?Bq/L and 228Ra was below the detection limit.  相似文献   

12.
227Ac,228Th,226Ra,210Po and210Pb can be present at rare earth chlorides. A radiochemical procedure is presented for the identification and determination of natural radioactive impurities in rare earth chlorides. The determination limits for these radionuclides were 1.5·10–4 to 3·10–1 Bq/g. The relative standard deviations for determining 10–2 Bq/g radionuclides were usually less than ±7%.  相似文献   

13.
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   

14.
234U, 238U, 226Ra, and 228Ra were analyzed in 14 Korean hot spring waters. Uranium was extracted with mixture of extractive scintillation cocktail containing HDEHP and 234U, 238U were analyzed with LSC. Radium isotopes were separated using Ba coprecipitation method and counted with LSC and 228Ra was also analyzed its daughter 228Ac with HPGe γ-detector. Among them 226Ra was ranged <0.01–0.155 Bq/L and 228Ra is below detection limit <0.1 Bq/L. And also, uranium content was ranged <0.01–49.7 μg/L and 234U/238U ratio was ranged 0.69–1.17.  相似文献   

15.
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   

16.
Summary Hokutolite, and hot spring water and river water collected recently at Peitou Hot Spring in Taiwan were analyzed for U, Th, Ra and 210Pb isotopes. Concentrations of major chemical elements were also measured. Hokutolite had its typical chemical composition make-up for this area. The concentrations of 238U, 234U, 232 Th, 230 Th, 228 Th, 226Ra, 228Ra and 210Pb in samples scrapped into 7 layers from the surface to the bottom of a hokutolite specimen were 0.0021-0.0068, 0.0022-0.0075, 1.47-2.07, 1.00-1.29, 1.56-1.97, 56.7-68.6, 1.46-2.06 and 25.9-36.0 Bq/g, respectively. All the radionuclides exhibited a relatively uniform distribution, and radioequilibrium was confirmed among 232 Th, 228Ra and 228 Th. From the relationship between the decay and growth of Th-series nuclides it was considered that the hokutolite studied was isolated from the stream water at least 70-80 years ago. The U/Th-series radionuclides in the hot spring water were in rather high concentrations and the enrichment of 228Ra and 228 Th to 232 Th was the most prominent feature. Evaluation of the distribution coefficients (Kd) using the data on hot spring water or river water and hokutolite indicated that Th (Kd = 104-105) in water was likely to be precipitated (and/or co-precipitated) with BaSO4 as Th(SO4)2 with a relatively high concentration into hokutolite, together with Ra (Kd = 106-107).  相似文献   

17.

The activity concentrations of 226Ra, 228Ra and 222Rn were measured in 87 groundwater samples to estimate the activity concentrations of these radionuclides and health impact due to intake of these radionuclides in groundwater of Jordan. The mean activity concentrations of 226Ra, 228Ra and 222Rn in groundwater were found to be 0.293?±?0.005 Bq L?1, 0.508?±?0.009 Bq L?1 and 58.829?±?8.824 Bq L?1, respectively. They give a mean annual effective dose of 0.481 mSv with mean lifetime risk of 24.599?×?10?4, exceeding the admissible limit of 10?4. Most of the received annual effective dose (59.15% of the total) is attributed to 228Ra.

  相似文献   

18.
Summary Samples of limestone, sand, marble, clay brick, red brick, gypsum, Portland cement and white cement collected from upper Egypt used in building manufacturing have been analyzed for the natural radionuclides 226Ra, 232Th and 40K usingg-ray spectrometry. The specific concentrations for 226Ra, 232Th and 40K, ranged from 20-88, 13-115 and 54-304 Bq/kg, respectively. The average specific activities of these radionuclides were compared. Higher values of 226Ra and 232Th could be noticed in marble while that of 40K was in red bricks. Radium equivalent activities, dose rate and the annual gonadal dose equivalents AGDE were calculated for the measured samples to assess the radiation hazard arising from using those materials in the construction of dwellings. The radioactive heat production values of the selected materials have also been determined. They vary from a minimum of 0.41 for white cement to a maximum of 5.52mW/m3 for marble samples. The calculated heat-production values are quite similar to those estimated in Corsica.</p> </p>  相似文献   

19.
There is an increased interest in measuring naturally occurring radioactive materials (NORM) like coal, fly ash considering health hazards caused by naturally occurring radionuclides. This paper presents activity concentration (AC) of 226Ra, 228Ra, 232Th, 238U and 40K in feed coal, bottom and fly ash samples from Philippines coal-fired thermal power plants using inductively coupled plasma mass spectrometry (ICP-MS) and high-purity germanium gamma spectroscopy (HPGe γ-spectroscopy). Coal, bottom and fly ash samples were digested using a microwave oven with a mixture of HNO3, HClO4 and HF. Uranium (238U) and thorium (232Th) ACs were also analyzed from samples using ICP-MS. A good correlation was found for the measurement of U and Th using both techniques (R2 = 0.97 and 0.94 respectively). ICP-MS measurements showed the highest AC of 232Th and 238U in fly ash and lowest for feed coal samples. With HPGe γ-spectroscopy measurements, highest AC (in Bq kg− 1) of 226Ra, 228Ra, 228Th and 40K, were noticed in fly ash followed by bottom ash and feed coal. ICP-MS method is rapid for the measurement of uranium and thorium in comparison to γ-spectroscopy as secular equilibrium is not required. Activity concentrations of bottom and fly ash samples were found to be within the reported values worldwide and below the International Atomic Energy Agency recommended values for regulatory control.  相似文献   

20.
Summary Technogenic and natural radionuclide content in red macroalgae (Ceramium rubrum, Corallina officinalisand Callithamnion corymbosum) from the Bulgarian Black Sea coast, collected in the period 1992-2003, was studied by low-level gamma-spectrometry. The data show that the nuclide concentrations depend on macroalgae species and coast locations. The highest nuclide content was measured in Ceramium rubrumspecies. The 137Cs mean value is 9.8 Bq/kg, 19.6 Bq/kg for 226Ra and 17 Bq/kg for 210Pb. The radionuclide pollution is considerably small due to the absence of nuclear facilities along the Bulgarian Black Sea coast.  相似文献   

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