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1.
Experiment procedures have been developed for the determination of 226Ra and 224Ra activity concentration in solid and liquid samples collected around a non-nuclear industrial area, by liquid scintillation counting. The different radiochemical procedures developed in this work, have been adaptations of a radiochemical procedure previously used, for 226Ra and 224Ra determinations by LSC in drinking water, which was improved, refined up and adapted to the type of sample to be applied. These improved radiochemical methods have been applied to waste samples (phosphogypsum) produced by two factories which are engaged in phosphoric acid production, and to waters collected from the Odiel river, where during the sampling period a fraction of these wastes were released. 226Ra activity concentrations in the phosphogypsum ranged from 673 to 1178 Bq/kg dry weight, indicating that the wastes are particularly enriched in this radionuclide. Consequently, high 226Ra levels were easily found in the river waters analysed, especially in the neighbouring zones of the waste discharges.  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.
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   

4.
The presence of 226 Ra in an estuary formerly affected by direct discharges of waste from a phosphate fertilizer complex has been investigated. Specific activities ranging from 3.6 to 45.2 mBq/l have been detected. In general, activity levels are lower than those detected when direct discharges were carried out. However, there is still a clear contamination due to the disposal of phosphogypsum in open air piles by the river. Moreover, it seems that 226 Ra is being redissolved from the contaminated bed sediments, which also contributes to an enhancement in the activity levels of the estuary waters.  相似文献   

5.
Three protocols (Method I: ion chromatography (IC) and extraction chromatography (EC), Method II: precipitation followed by IC, and Method III: adsorption onto MnO2 followed by IC-EC) were investigated to determine their applicability for the separation and pre-concentration of 226Ra in sediments. 226Ra recoveries, measured using the isotope dilution method with 228Ra as yield tracer, and the removal of spectral and non-spectral interferences were evaluated. The formation of polyatomic interferences at m/z = 226 from elements found in the matrix of sediments was also investigated to assess the level of separation required. Methods I and III were found to be the most effective with respect to recoveries and interference removal. The efficiency of a rapid microwave based protocol for the complete digestion of 1 g of sediment is also described. The method was tested and 226Ra concentrations in the millibecquerel range (fg) were determined in a standard reference material and sediment cores collected from Lake Baikal.  相似文献   

6.
The raw material used in the production of fetilizers is phosphate ore containing various amounts of naturally radioactive elements. During phosphate ore processing, owing to chemical properties of radium, practically all226Ra gets incorporated into phosphogypsum and becomes the main source of radioactivity. This study was carried out in a fertilizer factory in central Croatia, which may represent a site of significant environmental contamination due to fertilizer production and phosphogypsum deposition in the area. The purpose of this paper was to determine whether ingestion of drinking water in this area poses a health risk for the inhabitants. The results of our study confirmed the occurrence of226Ra in elevated concentrations in the samples of trickling waters. However, concurrent analyses of drinking water indicated that the risk of adverse health effects for the population living in the vicinity of a phosphate fertilizer plant is negligible.  相似文献   

7.
The sediment samples have been collected from estuarine regions of Mindola and Purna of Gujarat State. These samples are found to contain less than 3% of organic matter which scavange and carry most of the activity of226Ra, etc., to the sediment floor. The activities of226Ra are found to vary from 0.1 to 0.5 pCi/g, while210Pb activities lie in the range of 3 to 8 pCi/g. These activities find their way into the organisms present in sea water and then into fish which is finally consumed by humans. This paper gives in detail the sampling techniques, experimental procedures and the distribution of the isotopes of226Ra and210Pb in the estuarine regions and the concentration factors of226Ra in the region.  相似文献   

8.
A detailed study of the influence of barium on the electrodeposition of226Ra was made using two different procedures. High yields (80–90%) were attained when the amounts of barium were not very significant. However, the226Ra yields fell drastically for amounts slightly greater than 0.10–0.15 mg of Ba, according to the electrodeposition procedure. Samples containing trace amounts of barium less than 100–150 g can thus be treated with no barium-radium separation being required.210Po was also deposited, although practically no influence of barium on the Po plating was observed. The225Ra resolution rose uniformly (25 to 55 keV) as the amount of barium rose up to 1 mg. These resolutions allow one to make a direct accurate determination of226Ra as well as an indirect determination of224Ra and223Ra via measurement of their daughter products.  相似文献   

9.
The authors propose a method to determine 226Ra by using a solution of232U and its daughters in equilibrium as a tracer.224Ra of the232U solution can be used as yield determinant for226Ra. The growth of214Po from226Ra and of212Po from224Ra is measured at different times after the isolation of the radium fraction.  相似文献   

10.
The238U and226Ra contents of small-volume aerosols are determined by a chemical analysis technique. Mean activity concentrations of238U and226Ra in aerosols over approximately ten years are 0.29·10–5 and 0.93·10–5 Bq/m3, respectively. The yearly variation of238U and226Ra in aerosols is small. The concentrations of226Ra are always larger than those of238U in the same sampling time. The correlation of238U and226Ra cannot be recogonized (r=0.18). The concentrations of summer samples are greater than those of winter samples for238U. One of the causes of seasonal difference may be due to the fact that the components of aerosols are different according to soil size, soil components, weathering states, etc.  相似文献   

11.
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.
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   

13.
The distribution of226Ra and238U in various soils has been studied. Supposing that radioactive equilibrium were in existence, the average activities of226Ra and238U would show a nearly 11 correlation. As weathering affects radioactive equilibrium in surface soil, radioactive equilibrium was not in existence. Therefore, four kinds of soil were selected from different weathering conditions, viz. river bed soil, paddy field soil, field soil and uncropped soil. The226Ra/238U ratio of various soils lies in the range of 1.63 to 2.41. The activity concentrations of226Ra were greater than238U in various soils. The ratio226Ra/238U can be shown to be a quantitative index of weathering. Phosphatic manure contains238U and its daughter isotopes in concentrations far exceeding the average abundance in the earth's crust. But the cultivated soils (paddy field soil, field soil) are not affected by fertilizers in Kamisaibara.  相似文献   

14.
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   

15.
A new method has been developed at the Savannah River National Laboratory (SRNL) that can be used for the rapid determination of 226Ra in emergency urine samples following a radiological incident. If a radiological dispersive device event or a nuclear accident occurs, there will be an urgent need for rapid analyses of radionuclides in urine samples to ensure the safety of the public. Large numbers of urine samples will have to be analyzed very quickly. This new SRNL method was applied to 100 mL urine aliquots, however this method can be applied to smaller or larger sample aliquots as needed. The method was optimized for rapid turnaround times; urine samples may be prepared for counting in <3 h. A rapid calcium phosphate precipitation method was used to pre-concentrate 226Ra from the urine sample matrix, followed by removal of calcium by cation exchange separation. A stacked elution method using DGA Resin was used to purify the 226Ra during the cation exchange elution step. This approach combines the cation resin elution step with the simultaneous purification of 226Ra with DGA Resin, saving time. 133Ba was used instead of 225Ra as tracer to allow immediate counting; however, 225Ra can still be used as an option. The rapid purification of 226Ra to remove interferences using DGA Resin was compared with a slightly longer Ln Resin approach. A final barium sulfate micro-precipitation step was used with isopropanol present to reduce solubility; producing alpha spectrometry sources with peaks typically <40 keV FWHM (full width half max). This new rapid method is fast, has very high tracer yield (>90 %), and removes interferences effectively. The sample preparation method can also be adapted to ICP-MS measurement of 226Ra, with rapid removal of isobaric interferences.  相似文献   

16.
New method for simultaneous determination of228Ra and226Ra by using 3M's EMPORETM Radium Rad Disks in water has been developed. Both radionuclides226Ra and228Ra were counted through their daughter products,226Ra by conventional radon emanation techniques and228Ra through its daughter228Ac by using a proportional counter. Different molarity of diammonium hydrogen citrate were used for elution of228Ac and226Ra from EMPORETM Radium Rad Disks. 79% of228Ac was eluted in 10 ml of 0.0003M diammonium hydrogen citrate. The recovery of226Ra was 99% by using 40 ml of 0.2M diammonium hydrogen citrate adjusted by ammonium to pH 7.8.  相似文献   

17.
Summary The main shortcoming with the procedure to determine 226Ra in a gamma spectrum of an environmental sample by means of the 214Bi and 214Pb photopeaks is the likelihood of 222Rn leakage from the sample counting vial. An option to make such determination is to disregard the 226Ra gamma-contributions to the spectrum, other than 186.2 keV (3.5%), subtracting the 235U contribution to the 226Ra+235U peak at 186 keV. The use of this option to determine directly 226Ra activity concentrations in environmental samples and in NORM/TENORM matrices will be presented and discussed.  相似文献   

18.

The composite adsorbent prepared by mixing of polyacrylonitrile and clinoptilolite was used for investigating the adsorption behaviour of 226Ra in column system. The effective parameters like initial activity concentration, pH of the solution, contact time and temperature for adsorption behaviour of 226Ra were studied. Adsorption efficiency of 226Ra on composite adsorbent from aqueous solution was determined to 98.73 ± 0.59 % at pH 5.0 and 30 °C in a short time. The isotherm models were studied to evaluated adsorption characteristics of 226Ra onto composite adsorbent. The thermodynamic parameters were showing that the processes for 226Ra were exothermic. Adsorption kinetics of the radium is also studied.

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19.
Distributions of238U and226Ra in agricultural samples and cultivated soils have been studied over ten years. The crops are rice, spinach and Chinese cabbage. Two investigated areas have been selected (35° 18 N, 113° 35 E). The agricultural samples and soils were collected annually from May 1982 through October 1991. The activity concentrations of226Ra in agricultural samples are greater than those of238U. The transfer factors of238U,226Ra are from 0.06·10–3 to 1.2·10–3. The226Ra/238U ratios for three agricultural samples have their characteristic values.  相似文献   

20.
A time-saving and accurate technique for determining226Ra in groundwater and soil was examined, using high-resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS). The technique was applied to the determination of226Ra in groundwater and soil samples and compared with the conventional liquid scintillation counting method. This technique was capable of completing226Ra counting within 3 minutes, without the in-growth period to allow radon and its progeny to achieve secular equilibrium with the parent226Ra. The detection limits of HR-ICP-MS for226Ra in groundwater and soil were 0.19 mBq·1−1 and 0.75 Bq·kg−1, respectively, which were about 10 times lower than that of the liquid scintillation counter. The results obtained from HR-ICP-MS in groundwater and soil were in accordance with those of LSC within a relative error of about 13%.  相似文献   

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