共查询到20条相似文献,搜索用时 15 毫秒
1.
Zal U’yun Wan Mahmood Che Abd Rahim Mohamed Mei Wo Yii Zaharudin Ahmad Kamaruzzaman Ishak Abdul Kadir Ishak 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):107-113
Inventories and fluxes of 210Pb, 228Ra and 226Ra were determined in sediment cores collected at nine stations covering of the southern South China Sea and Malacca Straits
with the thickness of water column between 42 and 83 m depth. The inventories of 210Pb, 228Ra and 226Ra were calculated range from 0.15–2.55 Bq cm−2, 0.05–0.40 Bq cm−2 and 6.83–83.63 Bq cm−2, meanwhile the fluxes ranged from 0.005–0.079 Bq cm−2 yr−1, 0.009–0.048 Bq cm−2 yr−1 and 0.003–0.037 Bq cm−2 yr−1, respectively. The results show that the highest inventories and fluxes for 210Pb, 228Ra and 226Ra were found at station WC 01 and EC 05. Because there are additional sources of 210Pb, 228Ra and 226Ra, where water transport will brings more dissolved isotopes, influence of the transportation and deposition of suspended
particles, fast rate of regeneration and greater production of those radionuclides and others. 相似文献
2.
The analysis of 226Ra in natural waters can be tedious and time-consuming. For the determination and differentiation of activities of 226Ra and 222Rn in drinking water by γ-ray spectrometry a simple and fast method is presented. Activities of 226Ra > 0.5 Bq L−1 can be determined according to stabilization of the sample without further procedures. For a more sensitive detection sample
volumes of up to 5 litres are applicable by a rapid precipitation procedure without large expenditure. Further laborious enrichment
methods are not necessary. Thus, detection limits of 0.1 Bq L−1 can be obtained when using sample volumes of 5 litres. Therefore the method is suitable for the monitoring of radioactivity
in drinking water samples in accordance with the legal guidance of the European Union. 相似文献
3.
Tsuey-Lin Tsai Chun-Chih Lin Tsung-Yuan Wang Hwa-Jou Wei Lee-Chung Men 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):145-154
A rapid, accurate and less labor intensive approach to determining 226Ra in environmental samples was examined; this utilized quadrupole-based inductively coupled plasma mass spectrometry (ICP-QMS).
The procedure used chemical separation by ion exchange chromatography to remove most of the matrices after coprecipitation
with BaSO4. The average chemical recovery of the NIST SRM preparation method ranged from 60.5 to 85.9% using 133Ba as internal tracer by gamma counting. This technique was capable of completing a 226Ra measurement within 3 min. It did not require an in-growth period to allow radon and its progeny to achieve secular equilibrium
with the parent 226Ra as is needed for liquid scintillation analyzer (LSA). The method detection limits for the determination of 226Ra in geothermal water and sediment samples were 0.02 mBq L−1 (0.558 fg L−1) and 0.10 Bq kg−1 (2.79 fg g−1), respectively. The results obtained with various natural samples and the suitability of the method when applied to various
environmental matrices such as geothermal water and sediment are discussed. When ICP-QMS was compared to double-focusing magnetic
sector field inductively coupled plasma mass spectrometry (ICP-SFMS), good agreement was obtained with a correlation coefficient,
r
2 = 0.982. 相似文献
4.
C. H. R. Saueia B. P. Mazzilli M. H. T. Taddei 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(2):201-204
The phosphate rocks used for the production of phosphate fertilizers present in their composition radionuclides of the U and
Th series. During the chemical attack, the radionuclides are distributed to final products and phosphogypsum. A sequential
radiochemical procedure was implemented to determine the content of radionuclides alpha emitters in samples of fertilizers
and phosphogypsum produced in Brazil. The results obtained show that the levels of radioactivity present in the fertilizers
are of the same order of magnitude on those found in the phosphogypsum, reaching values up to 1158 and 457 Bq kg−1, for the U and Th series, respectively. 相似文献
5.
Sherrod L. Maxwell Brian K. Culligan 《Journal of Radioanalytical and Nuclear Chemistry》2012,293(1):149-156
A new rapid method for the determination of 226Ra in environmental samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used for emergency response or routine sample analyses. The need for rapid analyses in the event of a Radiological Dispersive Device or Improvised Nuclear Device event is well-known. In addition, the recent accident at Fukushima Nuclear Power Plant in March, 2011 reinforces the need to have rapid analyses for radionuclides in environmental samples in the event of a nuclear accident. 226Ra (T1/2?=?1,620?years) is one of the most toxic of the long-lived alpha-emitters present in the environment due to its long life and its tendency to concentrate in bones, which increases the internal radiation dose of individuals. The new method to determine 226Ra in environmental samples utilizes a rapid sodium hydroxide fusion method for solid samples, calcium carbonate precipitation to preconcentrate Ra, and rapid column separation steps to remove interferences. The column separation process uses cation exchange resin to remove large amounts of calcium, Sr Resin to remove barium and Ln Resin as a final purification step to remove 225Ac and potential interferences. The purified 226Ra sample test sources are prepared using barium sulfate microprecipitation in the presence of isopropanol for counting by alpha spectrometry. The method showed good chemical recoveries and effective removal of interferences. The determination of 226Ra in environmental samples can be performed in less than 16?h for vegetation, concrete, brick, soil, and air filter samples with excellent quality for emergency or routine analyses. The sample preparation work takes less than 6?h. 225Ra (T1/2?=?14.9?day) tracer is used and the 225Ra progeny 217At is used to determine chemical yield via alpha spectrometry. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory radium particles are effectively digested. The preconcentration and column separation steps can also be applied to aqueous samples with good results. 相似文献
6.
L. I. Tsikritzis 《Journal of Radioanalytical and Nuclear Chemistry》2005,264(3):651-656
Summary The distribution and origin of 40K, 226Ra, 228Ra and 137Cs has been investigated in trees, mosses and lichens in the basin of the West Macedonia Lignite Centre. In tree leaves 137Cs is negligible, while the 226Ra and 228Ra concentrations are affected by the fly ash particles. Concerning 226Ra and 228Ra values of mosses and lichens, which are systematically larger than those of unpolluted areas, the application of chemometrics proved that they originate mainly from the lignite fly ash. 相似文献
7.
W. Zhang K. Ungar J. Chen N. St-Amant B. L. Tracy 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(3):561-567
A quantitative method to determine the activity concentration of 226Ra in soil samples was established using high performance environmental gamma-ray spectrometry. In this method, a semi-empirical
calibration procedure was developed for full energy peak efficiency calculation utilizing the elemental composition of the
soil sample. Aatami software was used to deconvolute the 235U and 226Ra doublet at 185.7 keV and 186.2 keV, respectively, and to fit the baseline of the soil gamma-spectrum for the determination
of 226Ra activity. The results indicated that the Aatami doublet deconvolution procedure provides a rapid and accurate analysis
of a complicated spectrum in comparison with other cumbersome spectral interference correction methods. The study also compared
the results with those obtained by radon progeny (214Pb, or 214Bi) measurements and found that the deconvolution method provided a more accurate 226Ra activity as it is independent of the error caused by radon diffusion. This error can be quite large since the amount of
escaped radon gas through the sample container walls and sealing cannot be accurately quantified. 相似文献
8.
9.
N. M. Antovic V. Popovic I. Antovic N. Svrkota P. Vukotic 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):81-88
A coincidence method for measuring 137Cs, 40K, 226Ra and 232Th decay products activity in soil, vegetation and fish samples, was applied to the six-crystal gamma-coincidence spectrometer
PRIPYAT-2M. In this way, some problems appeared in simultaneous measurement of 137Cs, 226Ra and 232Th by NaI(Tl) detectors and the PRIPYAT-2M spectrometer were solved. The obtained results were agreeable with the HPGe spectrometer
ones. 相似文献
10.
Methodologies for the quantification of measurement uncertainties associated with the determination of 210Pb- and 210Po-specific activities by liquid scintillation counting (LSC) and alpha-particle spectrometry are presented, and are demonstrated
using the soil reference material IAEA-326. Major contributors to the combined uncertainty associated with the measurement
result of 210Pb were the uncertainties of net count rates in the 210Pb energy region of the sample spectrum and in the 210Bi energy region of the blank spectrum. The predominant sources of uncertainty in the measurement of 210Po were the uncertainties of net count rates in the regions of interest of 209Po and 210Po. The relative standard uncertainty of 210Po exponentially increases with the time interval between the sampling date and the separation date of Po, and this effect
is strongly dependent on the 210Po/210Pb activity ratio. When the specific activity of 210Pb is much higher than that of 210Po in the sample, the relative standard uncertainty of the 210Po determination increases significantly within a short time interval between the sampling date (or reference date) and the
separation date of Po in samples. 相似文献
11.
S. L. Maxwell III 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(3):651-655
Summary The measurement of radium isotopes in natural waters is important for oceanographic studies and for public health reasons.
Radium-226 (T1/2 = 1620 y) is one of the most toxic of the long-lived alpha-emitters present in the environment due to its long life and its
tendency to concentrate in bones, which increases the internal radiation dose of individuals. The analysis of 226Ra and 228Ra in natural waters can be tedious and time-consuming. Different sample preparation methods are often required to prepare
226Ra and 228Ra for separate analyses. A rapid method has been developed at the Savannah River Environmental Laboratory that effectively
separates both 226Ra and 228Ra (via 228Ac) for assay. This method uses MnO2 Resin from Eichrom Technologies (Darien, IL, USA) to preconcentrate 226Ra and 228Ra rapidly from water samples, along with 133Ba tracer. DGA Resinò (Eichrom) and Ln-Resinò (Eichrom) are employed in tandem to prepare 226Ra for assay by alpha-spectrometry and to determine 228Ra via the measurement of 228Ac by gas proportional counting. After preconcentration, the manganese dioxide is dissolved from the resin and passed through
stacked Ln-Resin-DGA Resin cartridges that remove uranium and thorium interferences and retain 228Ac on DGA Resin. The eluate that passed through this column is evaporated, redissolved in a lower acidity and passed through
Ln-Resin again to further remove interferences before performing a barium sulfate microprecipitation. The 228Ac is stripped from the resin, collected using cerium fluoride microprecipitation and counted by gas proportional counting.
By using vacuum box cartridge technology with rapid flow rates, sample preparation time is minimized. 相似文献
12.
R. Kandlbinder V. Geißler R. Schupfner O. Wolfbeis B. Zinka 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(1):113-119
The adsorption of Cs on clayey materials such as bentonite and Na-montmorillonite was studied in various electrolytic conditions
(concentration and composition), various solid to liquid ratios and various pH conditions. The results obtained for these
different conditions were modeled considering an exchange model associated to the surface complexation concept. Then, the
same approach was considered to model the sorption of Rb, which have the same chemical behavior than Cs. Experiments were
carried out for various electrolyte, pH, and Rb concentrations. The stoichiometries corresponding to the sorption of Rb on
bentonite and montmorillonite were then deduced from the experimental results. 相似文献
13.
Mei-Wo Yii Zal Uyun Wan-Mahmood 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):1465-1472
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
14.
Robert Kandlbinder Robert Schupfner Otto S. Wolfbeis 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(1):69-73
The determination of 228Ra by means of γ-spectrometry, in material containing significant quantities of 40K and Ca2+ such as bone ash results in increased values of counting uncertainty and lower limit of detection (LLD) because of a significant
contribution from the Compton continuum of 40K. However, 40K is widely removed from bone ash if 228Ra is coprecipitated with barium sulfate. As a result, the counting uncertainty and LLD are significantly reduced. A method
is presented for determination of very low activity concentrations of 228Ra. Impurities introduced by precipitation are negligible when applying high resolution γ-spectrometry. 相似文献
15.
Claudia Landstetter Christian Katzlberger 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(2):467-471
Screening measurements for 3H, 226Ra, 222Rn and 238U in ground water were performed within a ground- and drinking water project in Austria. The aim of this project is to get
an overview of the distribution of natural radionuclide activity concentration levels in ground water bodies. In some cases
this water is used for drinking water abstraction. In this paper methods and results of the screening measurements are presented.
Regions with high activity concentrations were identified and in these regions further investigation for 228Ra, 210Pb and 210Po will be conducted. 相似文献
16.
R. Periáñez A. Absi M. Villa H. P. Moreno G. Manjón 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(2):293-299
The Odiel and Tinto rivers, southwest Spain, form a fully mixed estuary. An industrial area that includes a complex dedicated
to the production of phosphate fertilizers is located by the Odiel River. This complex released phosphogypsum wastes directly
to the Odiel River and also disposed them on open air piles located by the Tinto River. Due to new EU regulations, wastes
are not directly released to the Odiel from 1998 on, although they are still disposed on the open air piles. The behavior
of 226Ra in a system like this estuary is complex, since radionuclides are affected by tidal actions and interactions with sediments
through adsorption/desorption reactions and erosion/deposition processes. A numerical 2D depth-averaged model of the estuary
has been developed, including processes mentioned above. It has been applied to reproduce experimental data measured after
a release from the industrial complex in the Odiel River and after an accidental release in the Tinto River from the gypsum
piles. The model has also been applied to simulate the self-cleaning process observed in the estuary after the direct releases
from the fertilizer complex were stopped. 相似文献
17.
T. Saito T. Ohta Y. Koike J. Sato 《Journal of Radioanalytical and Nuclear Chemistry》2003,255(3):535-538
The concentration of Ra isotopes in environmental water can be determined from the amount of Ra isotopes recovered in two successive batch operations a using cation exchange resin. The present analytical method is applicable to 10 liter of sample water having a Ra concentration larger than 10 mBq/l and is also applicable to the ordinary underground water of less than 1 mBq/l by use of 50 liter of sample water. In case where Ra concentration is extremely low, Mn-impregnated acrylic fiber can be used with a larger volume of water sample as an absorbent by soaking it in the water. 相似文献
18.
John Thompson Nie Luo Charlie Entenmann G. H. Miley Mitchell R. Swartz 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(3):753-761
Radioactive decay rates are to a large extent believed to be independent of the chemical environment. This is the physics
basis implicitly assumed in applications such as radioisotope dating. While this statement is a good approximation for most
radioactive decays, there are cases where a slight variation of 0.5% or more can be observed, as in the electron capture type
of decay. There are renewed interests in possible decay-rate changes with external parameters such as temperature, with controversy
as to the phenomenon’s authenticity. In this paper, we study the variation of radioactivity counts that significantly change (up to 50% or more) with temperature. We carefully studied the characteristics of the change and
found that the presence of a gaseous decay daughter can pose a serious challenge to a bona fide account of the intrinsic nuclear decay rate. After a careful solution to rate equations of the relevant isotopes under our
experimental conditions, we found that most of the radioactivity change could be accounted for by the diffusion and loss of
gaseous daughters under the heat, without a supposed change in the intrinsic nuclear decay rate. We hence demonstrate that
an accurate determination of the decay constant has to consider the possible diffusion of volatile components in the decay
chain. This is especially important in cases involving significant temperature change. 相似文献
19.
20.
M. Liezers O. T. FarmerIII M. L. Thomas 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(1):309-313
The measurement of fission product cesium isotopes 135Cs and 137Cs at low femtogram (fg) 10−15 levels in ground water by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) is reported. To eliminate the natural barium
isobaric interference on the cesium isotopes, in-line chromatographic separation of the cesium from barium was performed followed
by high sensitivity ICP-MS analysis. A high efficiency desolvating nebulizer system was employed to maximize ICP-MS sensitivity
~10 cps/fg. The three sigma detection limit for 135Cs was 2 fg/mL (0.1 μBq/mL) and for 137Cs 0.9 fg/mL (0.0027 Bq/mL) measured from the standard with analysis time of less than 30 min/sample. Cesium detection and
135/137 isotope ratio measurement at very low femtogram levels using this method in a spiked ground water matrix is also demonstrated. 相似文献