226Ra and 222Rn concentrations of spring waters in Balaton Upland of Hungary and the assessment of resulting doses

²²²Rn and ²²⁶Ra concentration of 18 frequently visited and regularly used, consumed spring waters on the Balaton Uplands have been measured by radon emanation method and alpha-spectrometry. ²²²Rn concentration varied between 1.5-55 Bq/l while ²²⁶Ra concentration between -601 mBq/l. The expected dose, between 14.1-119 mSv/y, has been assessed from the value of concentration supposing a daily consumption of 1 liter.     

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.     

Rapid method for determination of 228Ra in water samples

A new rapid method for the determination of ²²⁸Ra in natural water samples has been developed at the SRNL/EBL (Savannah River National Lab/Environmental Bioassay Laboratory) that can be used for emergency response or routine samples. While gamma spectrometry can be employed with sufficient detection limits to determine ²²⁸Ra in solid samples (via ²²⁸Ac), radiochemical methods that employ gas flow proportional counting techniques typically provide lower minimal detectable activity levels for the determination of ²²⁸Ra in water samples. Most radiochemical methods for ²²⁸Ra collect and purify ²²⁸Ra and allow for ²²⁸Ac daughter ingrowth for ~36 h. In this new SRNL/EBL approach, ²²⁸Ac is collected and purified from the water sample without waiting to eliminate this delay. The sample preparation requires only about 4 h so that ²²⁸Ra assay results on water samples can be achieved in <6 h. The method uses a rapid calcium carbonate precipitation enhanced with a small amount of phosphate added to enhance chemical yields (typically >90 %), followed by rapid cation exchange removal of calcium. Lead, bismuth, uranium, thorium and protactinium isotopes are also removed by the cation exchange separation. ²²⁸Ac is eluted from the cation resin directly onto a DGA Resin cartridge attached to the bottom of the cation column to purify ²²⁸Ac. DGA Resin also removes lead and bismuth isotopes, along with Sr isotopes and ⁹⁰Y. La is used to determine ²²⁸Ac chemical yield via ICP-MS, but ¹³³Ba can also be used instead if ICP-MS assay is not available. Unlike some older methods, no lead or strontium holdback carriers or continual readjustment of sample pH is required.     

Assessment of 226Ra and 228Ra activity concentration in west coast of India

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.     

Radium in drinking water in Quebec, Canada

Summary The median²²⁶Ra activity found in 216 drinking water samples in Quebec is 14 mBq/l. Only 6% of samples studied have an activity higher than the Maximum Contaminant Level of 111 mBq/l. The detection limit of the method is 4 mBq/l.     

Determination of228Ra in drinking water

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.     

Marine radioactivity concentration in the Exclusive Economic Zone of Peninsular Malaysia: 226Ra, 228Ra and 228Ra/226Ra

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.     

Determination of226Ra in water with a proportional counter

A modified version of the classical emanation method has been developed. It consists of emanation of radon from a 1 l water sample with argon, drying of the gas stream and counting of²²²Rn activity with a proportional counter. This method is very simple, reproducible, interference free and sensitive. The 3 detection limit obtained with a 100 min counting time is equal to 5 mBq l^–1. Several bottled mineral waters were analyzed by using this method and the mean and the median concentration found were equal to 50 and 20 mBq l^–1, respectively.     

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.     

Determination of 226Ra in biological samples by adsorption on specific adsorbers

The determination of 226Ra in biological samples, such as milk and grass, was studied. 226Ra analysis of cow's milk was studied starting from de-fatted milk. The proteins were eliminated by coagulation of the colloidal phase with trichloroacetic acid. Phosphorus was then removed by precipitating it as molybdophosphate and finally adsorption was carried out by using two different adsorbers in order to concentrate and purify radium. Lead rhodizonate (LEHRO) adsorbed on charcoal and partially reduced tin dioxide (PRTD) were utilised. A method for the determination of 226Ra in grass ashes was also investigated. The main interference, due to magnesium, hinders the use of LERHO, so the proposed procedure is based on adsorption of radium on PRTD at pH 9.5. The magnesium concentration was depleted by precipitating barium (carrier) and radium with calcium carbonate at pH 8 before the adsorption step. The high phosphorus concentration in grass also interferes in the determination of 226Ra; phosphorus was eliminated as above via molybdophosphate precipitation. The radium was carried by barium and spiked with 133Ba. The yield of the chemical procedure was evaluated on the basis of 133Ba activity. Radium samples were alpha-counted and the activity was evaluated with a suitable calibration curve. Both exchangers in the milk analysis and PRTD in grass analysis were shown to be helpful in order to set up an easily performed procedure, which allows many samples to be processed simultaneously. All the methods adopted were shown to be very sensitive. Under the experimental conditions used, with 1 L of milk or 5 g of grass ashes, the limit was about 3 mBq 226Ra L-1 milk and < 1 mBq 226Ra g-1 grass ashes.     

An improved method for technetium determination in environmental samples

Summary The recent developments of extraction chromatography and ICP-MS made easier the determination of ⁹⁹Tc in environmental samples. However, in the non-contaminated area, a pre-concentration procedure is necessary, because usually a large amount of sample is used for analysis. In this study, the ferrous ion (Fe²⁺) added as a reductant can make chemical yield from 50 to 80%, when larger than 100 liter water samples or 500 g soil samples are analyzed. The extraction chromatography with TEVA resin (EIChrom) and the measurement by ICP-MS have been developed using ^95mTc and ¹⁰³Ru as yield tracers. Detection limits of 3σ are 0.054 mBq/kg for 500 g soil and 0.032 µBq/lfor 500 l water. A pond named Hinotani, Mie Prefecture in the central part of Japan, was selected to be investigated as a natural system in a non-contaminated area. Surface soil near this pond, pond water and sediment were collected and analyzed for ⁹⁹Tc. In a high fall-out area, Okuetsu, Fukui Prefecture forest soil was collected and analyzed. The ⁹⁹Tc in the surface (0-5 cm) was 10.5±0.8 mBq/kg. The ⁹⁹Tc in Hinotani surface (0-5 cm) soil were 0.77±0.06 mBq/kg less than in Okuetsu. Technetium-99 has been determined in pond water, sediment (0-5 cm) and shrimps in the Hinotani pond, 0.25±0.02 mBq/l, 3.3±0.3 mBq/kg, 1.5±0.2 mBq/kg, respectively.     

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.     

Effect of humic acid,pH and ionic strength on the sorption of Eu(III) on red earth and its solid component

A highly sensitive separation procedure has been developed to investigate uranium and thorium activities and their isotopic ratios in environmental water samples in Tokushima, Japan. Uranium and thorium isotopes in environmental water samples were simultaneously isolated from interfering elements with extraction chromatography using an Eichrom UTEVA™ resin column. After the chemical separation, activities of U and Th isotopes coprecipitated with samarium fluoride (SmF₃) were measured by α-spectrometry. It has been confirmed that uranium isotopes are isolated successfully from thorium decay chains by analyzing a test aqueous solution as a simulation of an environmental water sample. The separation procedure has been first applicable to the determination of U and Th activities and their isotopic ratios in a drinking well water named “Kurashimizu” in Tokushima City, Japan. The specific activities of ²³⁸U and ²³²Th in “Kurashimizu” were deduced to be within the upper limits of <0.31 and <0.19 mBq/l, respectively.     

Studies on226Ra and210Pb activities and the concentration factors of226Ra in the surface organic layers of the estuarine sediments of Mindola and Purna rivers in India

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.     

Separation of Ra and Th from rock matrices for alpha-spectrometry

Dating rocks using²²⁶Ra/²³⁰Th isochrons demands radiochemical purification of radium and thorium. This paper presents an improved method. Rocks are solubilised by nitric/nydrofluoric digestion followed by dissolution of insoluble fluorides by boric/nitric acids, and Th is extracted by passing the 8M nitric solution through an anion column in nitrate form. The eluant contains Ra and Ba which are precipitated as sulphate and redissolved in alkaline EDTA. Complete separation of Ba and Ra from sulphate is on an AG 1×8 anion column in EDTA form, which was found better than the chloride form. The Ba+Ra is separated on an AG 50W×8 cation column, and uses CDTA as an eluant for Ba. Careful pH control is essential. Ra elutes later with EDTA or 4M HCl and is precipitated with 125 g barium as sulphate to yield a source suitable for -spectrometry, or further treated to electroplate the Ra. The yield tracers used are²²⁸Th and²²⁴Ra. Because the sample contains natural²²⁴Ra a correction must be applied, calculated from the amount of natural²³²Th in the Th spectrum. Th may be precipitated with 100 g of ferric iron and gives a spectrometry-quality source, but further purification and electrodeposition was found to be preferable. Variations on the method for the case of analysis of calcium-rich fish otoliths are described.     

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.     

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/...     

Advantages of low-background liquid scintillation alpha-spectrometry and pulse shape analysis in measuring222Rn, uranium and226Ra in groundwater samples

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.     

Determination and differentiation of <Superscript>226</Superscript>Ra and <Superscript>222</Superscript>Rn by gamma-ray spectrometry in drinking water

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.     

Radiochemical characterization of spring waters in Balaton Upland, Hungary, estimation of radiation dose to members of public

Hungary is rich in spring waters. A survey studying the naturally occurring alpha emitter radionuclides in 30 frequently visited and regularly consumed spring waters was conducted out in the Balaton Upland region of Hungary.²²⁶Ra, ²²⁴Ra, ²³⁴U, ²³⁸U and ²¹⁰Po activity concentrations were determined by using alpha spectrometry after separation from matrix elements. Average concentration (mBq L^{− 1}) of ²²⁶Ra, ²²⁴Ra, ²³⁴U, ²³⁸U and ²¹⁰Po in the spring waters is varied from 2.1 to 601, from < 1.1 to 65.4, from 3.9 to 741.9, from < 0.44 to 274.3 and from 2 to 15.2 respectively. In most cases radioactive disequilibrium was observed between uranium and radium isotopes. The doses for the analyzed samples of spring water are in the range 3.59–166.73 μSv y^{− 1} with an average 18.2 μSv y^{− 1} .This is well below the 100 μSv y^{− 1} reference level of the committed effective dose recommended by WHO. Only one water sample had a dose higher than 100 μSv y^{− 1}, mainly due to the contribution from radium (²²⁶Ra, ²²⁴Ra) and ²¹⁰Po isotopes. This study provides important information for consumers and authorities about their internal radiological exposure risk from spring water intake.