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1.
The presence of224Ra and226Ra in waters from an estuarine system which surrounds a phosphate fertilizer complex (southwest Spain) has been studied. The high activities obtained confirm that an important radiological impact from such industrial complex on its close environment is being produced. The influence of tidal oscillations and seasonal conditions on activity concentration has also been investigated.  相似文献   

2.
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   

3.
Direct determination of 226Ra in complex environmental matrices (biological and uranium ore samples) by collision-cell inductively coupled plasma mass-spectrometry was investigated. Possible polyatomic interferences were studied and their effects on 226Ra measurements were determined. The instrumental conditions for optimal signal-to-noise ratio for 226Ra were found. Concentrations of 226Ra in certified reference samples were measured using both external calibration and standard addition approaches. The best precision was obtained by applying standard additions. The absolute detection limit for 226Ra was 1 fg with optimal gas flow rates for the collision cell of 7 ml.min-1 for helium and 4 ml.min-1 for hydrogen.  相似文献   

4.
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   

5.
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   

6.
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   

7.
The distribution of some natural and anthropogenic radionuclides (226Ra,228Ra,210Po,40K,137Cs) in surface marine sediments from the harbours at Port Sudan and Sawakin on the Sudanese coast of the Red Sea has been investigated using α-spectrometry and direct high-resolution γ-spectrometry. The prime ams were to assess the levels of radioactivity and the influence of factors such as dredging and the organic matter content of the sediments on the distribution pattern of the radionuclides. The results have been evaluated and the leves indicate the absence of any possible enhancement by anthropogenic influx from the hinterland. The spatial distribution pattern is more heterogeneous in Sawakin harbour where some parts have recently been dredged and the sludge is removed to maintain the required depth. The data also show an insignificant relationship between the activity concentrations of all the radionuclides and the content of organic matter in the sediments.  相似文献   

8.
Summary A method for the determination of low-level radium isotopes in mineral and environmental water samples by alpha-spectrometry has been developed. Radium-225, which is in equilibrium with its mother 229Th, was used as a yield tracer. Radium were preconcentrated from water samples by coprecipitation with BaSO4and iron (III) hydroxide at pH 8-9 using ammonia solution, then isolated from uranium, thorium and iron using a Microthene-TOPO chromatography column at 8M HCl, separated from barium in a cation-exchange resin column using 0.05M 1,2-cyclohexylenedinitrilotetraacetic acid monohydrate at pH 8.5 as an eluant, and finally electrodeposited on a stainless steel disc in a medium of 0.17M (NH4)2C2O4at pH 2.6 and current density of 400 mA. cm-2, and counted bya-spectrometry. Optimum experimental conditions for radium separation, purification and electrodeposition have been studied and discussed in the paper. The lower limits of detection of the method are 0.11 mBq. l-1for 226Ra, 228Ra and 224Ra, respectively, if 2 l of water are analyzed. The method has been checked with a certified reference material IAEA-Soil-6 supplied by the International Atomic Energy Agency and reliable results were obtained. Eighteen water samples collected in Italy have been analyzed with the method, the mean radiochemical yields for radium were 86.2±6.5%. The obtained radium concentrations were in the range of 0.50-60.8 mBq. l-1for 226Ra, of 0.10-25.7 mBq. l-1for 228Ra, and of£LLD-7.97 mBq. l-1for 224Ra. The 228Ra/226Ra and 224Ra/226Ra ratios were in the range of 0.189-4.45 and£LLD-0.941, respectively.  相似文献   

9.
A study of the physical state of226Ra in uranium mill tailings was undertaken by Chemex Laboratories Ltd. under contract to NUTP. A test portion of a leached uranium ore was collected just prior to neutralization with lime and subjected to repetitive batch water leaching. The leachates were analyzed for barium, lead,226Ra, iron and sulphate. The experimental results suggest that226Ra is co-precipitated with lead sulphate during uranium leaching of the ore with sulphuric acid. The attainment of equilibrium conditions in the pore water of the leached ore then allows a re-proportioning of226Ra between solid lead and barium sulphates resulting in a depletion of226Ra in the outer layers of the crystals of solid lead sulphate and an enrichment in226Ra in the outer layers of solid barium sulphate.  相似文献   

10.
A procedure for the determination of natural uranium and226Ra in waters and soils has been carried out and applied to the analysis of samples for environmental radiological monitoring.226Ra determination consists of co-precipitation with BaSO4,222Rn emanation in toluene and finally liquid scintillation counting. Natural uranium is then determined by a fluorometric technique. This paper describes the method and the conditions that were tested to optimize it. The technique was found to be suitable for the analysis of surface and ground waters, samples from rivers, streams and lakes and soil samples, because of its few steps, short processing time, high recovery percentages and suitable detection limits.  相似文献   

11.
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   

12.
Since 2008, the authors have been conducting research into 222Rn and 226Ra activity concentrations in shallow circulation groundwaters in southern Poland. Measurements have been performed with a liquid-scintillation method and ultra low-level liquid-scintillation spectrometers α/β Quantulus 1220. The research carried out so far has demonstrated that in the Sudetes groundwaters with high activity concentrations of 222Rn and 226Ra are common. In other studied areas in southern Poland no shallow circulation groundwaters with high radon or radium concentrations have been found yet. The conducted research has demonstrated that the activity concentration of 222Rn dissolved in shallow circulation groundwaters in the Sudetes depends chiefly on the amount of radon, which after being released as gas from reservoir rocks is dissolved in waters flowing through these rocks. At the same time, the concentration of 222Rn dissolved in some shallow circulation groundwaters in the Carpathians is influenced significantly by the amount of radon produced from the decay of its parent ion 226Ra2+ dissolved in these waters.  相似文献   

13.
A complete methodology for 226Ra and 228Ra determination by alpha-particle spectrometry in environmental samples is being applied in our laboratory using 225Ra as an isotopic tracer. This methodology can be considered highly suitable for the determination of these nuclides when very low absolute limits of detection need to be achieved. The 226Ra determination can be performed at any time after the isolation of the radium isotopes from the analyzed samples while the 228Ra determination needs to be carried out at least six months later through the measurement of one of its grand-daughters. The method has been validated by its application to samples with known concentrations of these Ra nuclides, and by comparison with other radiometric methods.  相似文献   

14.
A new radioanalytical method was developed for rapid determination of 226Ra in drinking water samples. The method is based on extraction and preconcentration of 226Ra from a water sample to an organic solvent using a dispersive liquid-liquid microextraction (DLLME) technique followed by radiometric measurement using liquid scintillation counting. In DLLME for 226Ra, a mixture of an organic extractant (toluene doped with dibenzo-21-crown-7 and 2-theonyltrifluoroacetone) and a disperser solvent (acetonitrile) is rapidly injected into the water sample resulting in the formation of an emulsion. Within the emulsion, 226Ra reacts with dibenzo-21-crown-7 and 2-theonyltrifluoroacetone and partitions into the fine droplets of toluene. The water/toluene phases were separated by addition of acetonitrile as a de-emulsifier solvent. The toluene phase containing 226Ra was then measured by liquid scintillation counting. Several parameters were studied to optimize the extraction efficiency of 226Ra, including water immiscible organic solvent, disperser and de-emulsifier solvent type and their volume, chelating ligands for 226Ra and their concentrations, inorganic salt additive and its concentration, and equilibrium pH. With the optimized DLLME conditions, the accuracy (expressed as relative bias, B r ) and method repeatability (expressed as relative precision, S B ) were determined by spiking 226Ra at the maximum acceptable concentration level (0.5 Bq L−1) according to the Guidelines for Canadian Drinking Water Quality. Accuracy and repeatability were found to be less than −5% (B r ) and less than 6% (S B ), respectively, for both tap water and bottled natural spring water samples. The minimum detectable activity and sample turnaround time for determination of 226Ra was 33 mBq L−1 and less than 3 h, respectively. The DLLME technique is selective for extraction of 226Ra from its decay progenies.  相似文献   

15.
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   

16.
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   

17.
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   

18.
Radioactivity measurements were carried out in 26 groundwater samples from Tunisia. Activity concentrations of uranium were studied by radiochemical separation procedures followed by alpha spectrometry and that for radium isotopes by gamma-ray spectrometry.The results show that, the concentrations in water samples range from 1.2 to 69 mBq/L.1, 1.3 to 153.4 mBq/L, 2.0 to 1630.0 mBq/L and 2.0 to 1032.0 mBq/L for 238U, 234U, 226Ra and 228Ra, respectively. The U and Ra activity concentrations are low and similar to those published for other regions in the world. The natural radioactivity levels in the investigated samples are generally increased from mineral waters through therapeutic to the spring waters.The results show that a correlation between total dissolved solids (TDS) values and the 226Ra concentrations was found to be high indicating that 266Ra has a high affinity towards the majority of mineral elements dissolved in these waters. High correlation coefficients were also observed between 226Ra content and chloride ions for Cl?–Na+ water types. This can be explained by the fact that radium forms a complex with chloride and in this form is more soluble.The isotopic ratio of 234U/238U and 226Ra/234U varies in the range from 0.8 to 2.6 and 0.6 to 360.8, respectively, in all investigated waters, which means that there is no radioactive equilibrium between the two members of the 238U series. The fractionation of isotopes of a given element may occur because of preferential leaching of one, or by the direct action of recoil during radioactive decay.The annual effective doses due to ingestion of the mineral waters have been estimated to be well below the 0.1 mSv/y reference dose level.  相似文献   

19.
Relative gamma-ray emission probabilities in the decay of 226Ra and its decay products have been measured using a HPGe detector. The resulting data have been evaluated together with five previously published sets of 226Ra gamma-ray emission probabilities.  相似文献   

20.
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   

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