226RA analysis in sea and river water by adsorption on specific adsorbers

A method to analyse 226Ra in sea water Ra in sea water was investigated. The chemical procedure is based on adsorption of radium and barium, used as a carrier, on the specific adsorber PRTD at pH 9.5. The main interference is due to magnesium. The magnesium concentration is depleted by precipitating barium (carrier) and radium with calcium carbonate at pH 8 before the adsorption step. The proposed chemical procedure is simple and easily performed. The overall chemical yield is evaluated on the basis of the 133Ba spike. The sensitivity of the method is related to the volume of sea water. Under the experimental conditions used, 5 L of sea water, the limit was 1 226Ra mBq/L of water. The method may be also applied to the analysis of radium in river water, by omitting the carbonate precipitation.     

Use of inorganic adsorbers in radium analysis

Two new simple methods were studied for the analysis of radium in fresh waters by concentration and purification. Both methods are based on the use of an inorganic selective adsorber, namely basic lead rhodizonate, LERHO, and partially reduced tin dioxide (PRTD). The procedures were checked by using filtered fresh waters spiked with 0.1 Bq of²²⁶Ra, and in the presence of few μg/l of barium. In each experiment¹³³Ba radioisotope was added to water samples to measure the yield of the overall procedure by γ-counting. Barium and radium were adsorbed from basic solutions on LERHO packed chromatographic column in the first procedure, while batch experiments were preferred for the adsorption on PRTD. After separation,²²⁶Ra and barium were eluted from the exchangers and co-precipitated onto small filters as thin film, supported on an inactive barium sulphate substrate, to be submitted to alpha-and gamma-spectrometry. Both methods gave promising results.     

Recrystallization of 223Ra with barium sulfate

In this work, the kinetics of barium sulfate recrystallization has been studied in acidic 0.01 mol dm^?3 sodium sulfate solution using ²²³Ra and ¹³³Ba tracers at very low total radium concentration, i.e. less than 10^?13 mol dm^?3. It was found that the system follows the homogeneous recrystallization model and that recrystallization rates, inferred by the decrease of ²²³Ra and ¹³³Ba in the aqueous solution, are fast. Therefore, even at very low concentrations, below the solubility limit, radium will be retained by barium sulfate—a mineral present in the deep underground repository.     

Rapid determination of radium isotopes by alpha spectrometry

An efficient analytical method for the determination of low-levels of²²⁶Ra and²²⁴Ra by alpha spectrometry is described. A cation exchange column was used to separate the analyte from other constituents in the sample (1–50 mL). After preconcentration and separation, the radium was electrodeposited onto a stainless steel disc from a solution of ammonium oxalate and hydrochloric acid. The electrodeposition was accomplished by the addition of platinum in microgram amounts. Linear responses were greater than two orders of magnitude. Detection limits of the procedure, taken as three times the standard deviation of several reagent blank analyses, were (1.8±0.3)×10^–4 Bq and (2.9±0.3)×10^–4 Bq for²²⁶Ra and²²⁴Ra, respectively. Recoveries of²²⁶Ra and²²⁴Ra ranged from 90% to 100% when samples of drinking water, well water, and dissolved bones were analyzed. Precision was calculated to be less than 5% for the determination of²²⁶Ra. Matrix effects were studied for salts of barium, magnesium, iron, and calcium.     

224Ra correction for determination of 226Ra in environmental materials

The most commonly available 226Ra determination was too time-consuming to be suited to 226Ra monitoring for the accidental release. The formula for determination of 226Ra was derived by 224Ra correction for WHO's equation. A rapid determination of 226Ra in environmental materials was made possible by using this formula. The 226Ra values of the soil and natural water at Ningyoh-Tohge obtained by the present method were in good agreement with those by the conventional WHO method. It was demonstrated that 226Ra of more than about 37 mBq (1 pCi) in the sample could be determined within 4 days by this method.     

Influence of Ba on the electrodeposition of226Ra

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.     

Separation and electrodeposition of226Ra

The chemical behavior of calcium, barium and radium in the ion exchange resins Dowex 50W-X8, AG 50W-X8 and Merk I in the presence of ammonium tartrate, EDTA, and citrate has been studied. No differences were observed in results while using any one of the three resins. Calcium, barium and radium were fixed to the exchange column at pH 4.8 EDTA solution. Calcium was eluted in an EDTA solution at pH 5.3, barium and radium between pH 8–11. Elution in citrate media for calcium was achieved at pH 6.1 and for radium at pH 10. In ammonium tartrate, calcium was eluted at pH 6, barium and radium at pH 11.5. Radium was also eluted from the ion exchange resins with a 2M nitric acid solution. The radium free of calcium was electrodeposited onto a stainless steel disc cathode using a 0.1 M potassium fluoride solution, pH 12–14, with a yield of >50%. The energies of²²⁶Ra were analyzed through high resolution -spectra. The²²⁶Ra utilized for these experiments was separated from Mexican carnotite.     

Spatial distribution of radium in coastal marine waters of Tamil Nadu

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.     

Determination of uranium and radium concentrations in the waters of the Grand Canyon by alpha spectrometry

In order to establish baseline information for current and future mining operations, water samples from the Colorado River and its tributaries have been analyzed for Ra-226 and uranium isotopes. Ra-226 was separated by coprecipitation on BaSO₄ followed by alpha spectrometry. Ba-133 was used as a tracer for yield determination. Uranium was separated by a combination of BaSO₄ precipitation and solvent extraction followed by coprecipitation on CeF₃ for alpha spectrometry.Results indicate that radium and uranium levels in the Colorado River and its tributaries, except the Little Colorado River, are below the EPA specifications [1] for drinking water of 185 mBq/liter (5 pCi/1) for Ra-226 and 433 mBq/liter (11.7 pCi/1) for U-238. However, the specific sources for elevated uranium and Ra-226 concentrations in the Little Colorado River should be identified, and the potential impacts from leaching of the naturally exposed mineralization inside the Grand Canyon should be investigated.     

Natural radioactivity levels in mineral,therapeutic and spring waters in Tunisia

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.     

Removal of 226Ra from aqueous media and its thermodynamics and kinetics

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.

     

Rapid method for 226Ra and 228Ra analysis in water samples

Summary The measurement of radium isotopes in natural waters is important for oceanographic studies and for public health reasons. Radium-226 (T_1/2 = 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 Resin^ò (Eichrom) and Ln-Resin^ò (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.     

Radium-224 in natural waters measured by γ-ray spectrometry

A method based on Ge(Li) γ-ray spectrométry is applied to the determination of ²²⁴Ra (t_{$\text{1}\text{2}$}= 3.64 days) in natural waters. The ²²⁴Ra is first removed from several hundred liters of water by preconcentration onto manganese dioxide-impregnated acrylic fibers. The fibers are leached, radium is coprecipitated with barium sulfate, and the γ-ray activity is counted so that activity ratios among ²²⁴Ra, ²²⁵Ra and ²²⁶Ra can be calculated. Concentrations are determined by using the ²²⁶Ra concentration determined on a small separate sample. Results from samples collected from ground water, estuarine, and continental shelf environments are presented.     

Determination of radium isotopes by BaSO4 coprecipitation for the preparation of alpha-spectrometric sources

A coprecipitation procedure for the preparation of -spectrometric sources for radium, using BaSO₄ as carrier, has been applied to the determination of alpha radium isotopes in water samples. The use of¹³³Ba as a suitable tracer for radium determination and possible losses of radon isotopes from the sources are studied and discussed.     

Rapid determination of 226Ra in emergency urine samples

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.     

A rapid method for the separation of radium from Tuwa spring waters for determining the activity ratio of223Ra/226Ra

A rapid method for the separation of radium in spring waters of Tuwa, Panchamahal district, Gujarat State, India, containing large amounts of calcium (0.5 g/l) has been developed. It consists of concentrating polyvalent cations from 21 samples using 10 g of carboxylate exchanger, Zeokarb 226 (NH ₄ ⁺ ) and then precipitating radium as sulfate in the presence of 400 μg of barium.     

<Superscript>226</Superscript>Ra and <Superscript>228</Superscript>Ra determination in environmental samples by alpha-particle spectrometry

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.     

Determination of radium isotopes in mineral and environmental water samples by alpha-spectrometry

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.     

吉林矿泉水放射性水平的调查分析

为了解吉林省矿泉水的放射性水平及分布特点,依据《饮用天然矿泉水标准》,采用FD- 125型室内氡钍测定仪及FH 463A型自动定标器和BH 1217型弱α,β测量仪对5个行政区域矿泉水中226 Ra和总α、总β放射性核素水平进行了测定.结果表明,矿泉水中226Ra、总α、总β的放射性活度范围为5.5～11.4 mBq/...