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.     

Uranium determination in water samples with elevated salinity from Southern Poland by micro coprecipitation using alpha spectrometry

Due to the importance of water in human life, its quality must be strictly controlled; so simple and reliable analytical methods must be available. For this purpose a rapid procedure for the determination of uranium isotopes in natural water samples with elevated salinity was adopted. It was tested in 16 water samples from Upper and Lower Silesia Regions in Poland. Water samples had salinity in a range of 290–26,925 mg l^{− 1}.In water samples the concentrations of ²³⁴U and ²³⁸U ranged from 2.07 to 52.08 mBq l^{– 1} and from 2.18 to 43.38 mBq l^{– 1} respectively, while ²³⁵U level was below MDA (0.7 mBq l^{− 1}).The isotopic ratio of ²³⁴U/²³⁸U varies in the range from 0.949 to 3.344 in all investigated waters which means that there is usually no radioactive equilibrium between the parent nuclide ²³⁸U and its daughter product ²³⁴U.These results do not show a correlation between total dissolved solids (TDS) values and concentration of dissolved uranium isotopes.Committed effective dose for adults due to uranium intake as a result of drinking water usage was in range of 0.15–3.29 µSv y^{− 1} with an average value of 1.09 µSv y^{− 1} far below the 100 µSv y^{− 1} WHO recommendation.     

Uranium series disequilibrium in the coastal surface sediments and sea water of the Arabian Sea

Nearshore surface sediments from various locations of the West Coast of India were leached by saturated ammonium carbonate solution for the extraction of uranium isotopes. The reagent chosen was found to have high efficiency for leaching uranium isotopes without attacking the mineral core of the sediment particle. The activity ratios of²³⁴U/²³⁸U are in the range of 1.11 to 1.14 and the activity ratios of²³⁵U/²³⁵U are in the range of 0.045 to 0.047. The respective activity ratios in leachates, and residues after removal of surface organic matter from the sediment particles by treatment with hydrogen peroxide and 0.05M HCl, revealed disequilibrium between²³⁸U and²³⁴U only in the surface organic matter. The activity ratios of²³⁴U/²³⁸U and²³⁵U/²³⁸U have also been determined in some seawater samples from the Arabian Sea.     

Determination of234U/238U and235U/238U ratios from commercially available uranium compounds by α-spectrometry

The²³⁴U/²³⁸U and²³⁵U/²³⁸U ratios from uranium compounds by -spectrometry technique have been obtained. Ten commercially available uranium reagents were analyzed. The well-separated peaks corresponding to uranium isotopes are evident, providing an energy spectrum of the -particles of uranium isotopes. It was found that some commerical uranium salts were depleted in²³⁴U and²³⁵U.     

Determination of uranium isotopes in environmental samples

The determination of isotopes of uranium by alpha spectrometry in different environmental components (sediments, soil, water, plants and phosphogypsum) is presented and discussed in this paper. The alpha spectrometry is a very convenient and good technique for activity concentration of natural uranium isotopes (²³⁴U, ²³⁵U, ²³⁸U) in environmental samples and provides the most accurate determination of isotopic activity ratios between ²³⁴U and ²³⁸U. The analysis were provided information about possible sources of high concentrations of uranium in the examined sites determined by anthropogenic sources. The calculation of values ²³⁴U/²³⁸U in all analyzed samples was applied to identifying natural or anthropogenic uranium origin. Activity concentration of uranium isotopes in analyzed environmental samples shows that measurement of uranium levels is of great importance for environmental and safety assessment especially in contaminated areas (phosphogypsum waste heap).     

Concentration, distribution and characteristics of depleted uranium (DU) in the Kosovo ecosystem: A comparison with the uranium behavior in the environment uncontaminated by DU

The smear samples of the penetrator were analyzed for the determination of the uranium composition. The obtained relative composition (m/m) of uranium isotopes in all the smear samples is in the range of 99.76-99.78% for ²³⁸U, 0.000659-0.000696% for ²³⁴U, 0.213-0.234% for ²³⁵U, and 0.00274-0.00328% for ²³⁶U, showing characteristics of depleted uranium (DU). The uranium concentrations in Kosovo soil and water samples as well as biological samples were investigated. It was found that the uranium concentrations in the Kosovo soil samples are in the range of 11.3-2.26·10⁵ Bq·kg^-1 for ²³⁸U, 10.3-3.01·10⁴ Bq·kg^-1 for ²³⁴U, 0.60-3251 Bq·kg^-1 for ²³⁵U, and ￡0.019-1309 Bq·kg^-1 for ²³⁶U. The obtained activity ratios are in the range of 0.112-1.086 for ²³⁴U/²³⁸U, 0.0123-0.1144 for ²³⁵U/²³⁸U, and 0-0.0078 for ²³⁶U/²³⁸U, indicating the presence of DU in about 77% of the surface soil samples. At a specific site, the DU inventory in the surface soil is about 140 mg·cm^-2, which is 1.68·10⁶ times higher as the estimated mean DU dispersion rate in the region. The uranium concentrations in Kosovo lichen, mushroom, bark, etc., are in the range of 1.97-4.06·10⁴ Bq·kg^-1 for ²³⁸U, 0.48-5158 Bq·kg^-1 for ²³⁴U, 0.032-617 Bq·kg^-1 for ²³⁵U, and ￡0.019-235 Bq·kg^-1 for ²³⁶U with mean activity ratios of 0.325±0.0223 for ²³⁴U/²³⁸U, of 0.0238±0.0122 for ²³⁵U/²³⁸U, and 0.0034±0.0028 for +U/²³⁸U, indicating the presence of DU in the entire sample. On the contrary, the uranium concentrations in Kosovo water samples are low, compared with the water samples collected in central Italy, indicating the presence of negligible amount of DU. The uranium isotopes in Kosovo waters do not constitute a risk of health at the present time. This revised version was published online in July 2006 with corrections to the Cover Date.     

Recovery and pre-concentration of americium (III) from dilute acid solutions using an emulsion liquid membrane containing di-2-ethylhexyl phosphoric acid (D2EHPA) as extractant

Radiochemical results of U isotopes (²³⁴U, ²³⁵U and ²³⁸U) and their activity ratios are reported for well waters as local sources of drinking waters collected from the ten settlements around the Semipalatinsk Nuclear Test Site (SNTS), Kazakhstan. The results show that ²³⁸U varies widely from 3.6 to 356 mBq/L (0.3–28.7 μg/L), with a factor of about 100. The ²³⁸U concentrations in some water samples from Dolon, Tailan, Sarzhal and Karaul settlements are comparable to or higher than the World Health Organization’s restrictive proposed guideline of 15 μg (U)/L. The ²³⁴U/²³⁸U activity ratios in the measured water samples are higher than 1, and vary between 1.1 and 7.9, being mostly from 1.5 to 3. The measured ²³⁵U/²³⁸U activity ratios are around 0.046, indicating that U in these well waters is of natural origin. It is probable that the elevated concentration of ²³⁸U found in some settlements around the SNTS is not due to the close-in fallout from nuclear explosions at the SNTS, but rather to the intensive weathering of rocks including U there. The calculated effective doses to adults resulting from consumption of the investigated waters are in the range 1.0–18.7 μSv/y. Those doses are lower than WHO and IAEA reference value (100 μSv/y) for drinking water.     

Uranium isotopes in carbonate aquifers of arid region setting

Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of ²³⁸U and ²³⁵U in groundwater of four selected locations in the southern Arabian peninsula, namely at two locations within the United Arab Emirates (UAE) and two locations in Oman are discussed. The analyses of the uranium isotopes were performed using ICP-MS and the results indicated a range of concentrations for ²³⁵U and ²³⁸ U at 3–39 ng L^?1 (average: 18 ng L^?1) and 429–5,293 ng L^?1 (average: 2,508 ng L^?1) respectively. These uranium concentrations are below the higher permissible WHO limit for drinking water and also comparable to averages found in groundwater from similar aquifers in Florida and Tunisia. Negative correlation between rainfall and uranium concentrations suggests that in lithologically comparable aquifers, climate may influence the concentration of uranium in subtropical to arid regions.     

238U, 234U and 226Ra concentrations in mineral waters and their contribution to the annual committed effective dose in Turkey

Activity concentrations of ²³⁴U, ²³⁸U and ²²⁶Ra in mineral waters were determined on the basis of nine water bottling facilities using alpha particle spectrometry. The mineral water samples were collected from three geographic regions of Turkey. The radiochemical separation used in the uranium analysis is based on the isolation of uranium radioisotopes from other radionuclides such as Th, Am, Pu and Np using UTEVA resin. Alpha sources were prepared using electrodeposition method. The activity concentration of ²²⁶Ra was determined after deposition on a membrane using BaSO₄ co-precipitation method. The activity concentrations (mBq L^?1) of ²²⁶Ra, ²³⁸U and ²³⁴U ranged from <0.56 to 165, from <0.42 to 439 and from <0.42 to 464, respectively. The measured activity concentrations were used for the calculation of the average total annual effective ingestion doses for children and adults. The committed effective doses were calculated for three different scenarios according to mineral water consumption rate. In the most extreme scenario (for age group 12–17), all water samples except MW1 and MW2 cause annual committed effective doses below the reference level (0.1 mSv year^?1) recommended by World Health Organization (WHO).     

Activity disequilibrium between 234U and 238U isotopes in natural environment

The aim of this work was to calculate the values of the ²³⁴U/²³⁸U activity ratio in natural environment (water, sediments, Baltic organisms and marine birds from various regions of the southern Baltic Sea; river waters (the Vistula and the Oder River); plants and soils collected near phosphogypsum waste heap in Wi?linka (Northern Poland) and deer-like animals from Northern Poland. On the basis of the studies it was found that the most important processes of uranium geochemical migration in the southern Baltic Sea ecosystem are the sedimentation of suspended material and the vertical diffusion from the sediments into the bottom water. Considerable values of the ²³⁴U/²³⁸U are characterized for the Vistula and Oder Rivers and its tributaries. The values of the ²³⁴U/²³⁸U activity ratio in different tissues and organs of the Baltic organisms, sea birds and wild deer are varied. Such a large variation value of obtained activity ratios indicates different behavior of uranium isotopes in the tissues and organisms of sea birds and wild animals. This value shows that uranium isotopes can be disposed at a slower or faster rate. The values of the ²³⁴U/²³⁸U activity ratio in the analyzed plants, soils and mosses collected in the vicinity of phosphogypsum dumps in Wi?linka are close to one and indicate the phosphogypsum origin of the analyzed nuclides. Uranium isotopes ²³⁴U and ²³⁸U are not present in radioactive equilibrium in the aquatic environment, which indicates that their activities are not equal. The inverse relationship is observed in the terrestrial environment, where the value of the of the ²³⁴U/²³⁸U activity ratio really oscillates around unity.     

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.     

Investigation of radioactive lead,uranium, and thorium in environmental waters by extraction chromatography resins

A time-saving and sensitive method for monitoring low concentration (activities) of ²¹⁰Pb, ²³²Th, and ²³⁰Th and ²³⁸U, ²³⁴U, and ²³⁵U in water samples has been developed. Through the combination of co-precipitation and extraction chromatography by 3M RAD disks and UTEVA (Eichrom) columns effective radiochemical separation of the analytes was carried out. Thorium and uranium activities were determined by alpha spectrometry and lead activity by LSC, respectively. The minimal detectable activities obtained were 0.6?Bq?m^?3 for uranium, 0.29?Bq?m^?3 for thorium, and 2.5?Bq?m^?3 for ²¹⁰Pb. More than 150 different waters were analysed for uranium content and only 30 for lead and thorium. The investigations are still in progress.     

<Superscript>234</Superscript>U/<Superscript>238</Superscript>U and <Superscript>235</Superscript>U/<Superscript>238</Superscript>U ratios in domestic water from the environs of Obuasi mine in Ghana

Activity concentrations of ²³⁸U, ²³⁵U and ²³⁴U were determined in different sources of drinking water at the Obuasi gold mines and its surrounding areas in Ghana. Water samples collected from the mines and its surrounding areas were analyzed using direct gamma-ray spectrometry and neutron activation analysis. The ²³⁴U/²³⁸U and ²³⁵U/²³⁸U ratios were calculated and the mean values range from 1.27 to 1.38 and from 0.044 to 0.045 respectively. The average ²³⁴U/²³⁸U ratio was from 1.27 for groundwater to 1.38 for treated water, demonstrating the lack of equilibrium. The average ²³⁵U/²³⁸U activity ratio is 0.045, indicating that only natural uranium was detected in the samples investigated.     

The transfer of uranium from sediment to water along Jucar River, Spain

The effect of sediment size, pH, temperature and conductivity on the transfer of uranium from sediment to water has been studied. The uranium concentration and the²³⁴U/²³⁸U,²³⁵U/²³⁸U activity ratios were measured in water, sediments and suspended matter sampled from Jucar River, using low level alpha-spectrometry. Distribution factors were obtained from these measurements. A more detailed sampling was done in the neighbourhood of the Cofrentes Nuclear Plant (Valencia, Spain). Total uranium activity,²³⁴U/²³⁸U activity ratio and distribution factors for²³⁴U and²³⁸U were found to vary with pH. Leaching and dilution, which depend on pH and salinity, are the probable mechanisms for these changes.     

Radiochemical determination of uranium and radium isotope in natural water using liquid scintillation counter

²³⁴U, ²³⁸U, ²²⁶Ra, and ²²⁸Ra were analyzed in 14 Korean hot spring waters. Uranium was extracted with mixture of extractive scintillation cocktail containing HDEHP and ²³⁴U, ²³⁸U were analyzed with LSC. Radium isotopes were separated using Ba coprecipitation method and counted with LSC and ²²⁸Ra was also analyzed its daughter ²²⁸Ac with HPGe γ-detector. Among them ²²⁶Ra was ranged <0.01–0.155 Bq/L and ²²⁸Ra is below detection limit <0.1 Bq/L. And also, uranium content was ranged <0.01–49.7 μg/L and ²³⁴U/²³⁸U ratio was ranged 0.69–1.17.     

Natural radioactivity in bottled natural spring,mineral and therapeutic waters in Poland

Activities of ²³⁸U, ²³⁴U, ²²⁸Ra, ²²⁶Ra, and ²²⁴Ra as well as total α- and β-activities of 23 bottled spring, mineral and therapeutic waters produced and distributed in southern and central Poland are presented. The activities vary from a few tenth to a few mBq·L⁻¹ for uranium and to several hundred mBq·L⁻¹ for radium isotopes. The activities of ⁴⁰K were calculated from chemical analyses of potassium and checked for several mineral waters by gamma-spectrometer coupled with an HPGe detector. Positive correlation between water mineralization and activities of ⁴⁰K, ²²⁶Ra, as well as total alpha- and total beta-activities were observed. The radiological annual doses were calculated for all investigated waters and for different human age groups assuming the consumption of 1 liter of water per day. The calculated committed effective dose rate from uranium and radium isotopes resulting from consumption of the investigated waters exceeds the recommended value of 0.1 mSv per year in seventeen cases for infants and in one case for adults.     

Isotopic analysis of uranium in NIST SRM glass by femtosecond laser ablation MC-ICPMS

We employed femtosecond Laser Ablation Multicollector Inductively Coupled Mass Spectrometry for the determination of uranium isotope ratios in a series of standard reference material glasses (NIST 610, 612, 614, and 616). The uranium in this series of SRM glasses is a combination of isotopically natural uranium in the materials used to make the glass matrix and isotopically depleted uranium added to increase the uranium elemental concentration across the series. Results for NIST 610 are in excellent agreement with literature values. However, other than atom percent ²³⁵U, little information is available for the remaining glasses. We present atom percent and isotope ratios for ²³⁴U, ²³⁵U, ²³⁶U, and ²³⁸U for all four glasses. Our results show deviations from the certificate values for the atom percent ²³⁵U, indicating the need for further examination of the uranium isotopes in NIST 610-616.     

<Superscript>234</Superscript>U/<Superscript>235</Superscript>U activity ratios as a probe for the <Superscript>238</Superscript>U/<Superscript>235</Superscript>U half-life ratio

High-resolution alpha-particle spectrometry was performed on three uranium materials enriched in ²³⁵U. Besides the ²³⁵U peaks, separate peaks belonging to impurity traces of ²³⁴U could be quantified. Relying on the isotopic composition of the uranium, as determined by mass spectrometry, the ratio of the half-lives of ²³⁸U and ²³⁵U was determined via the activity ratio of ²³⁴U and ²³⁵U in the materials. As an intermediate link, the ²³⁴U/²³⁸U half-life ratio was taken from published mass spectrometric analyses of ‘secular equilibrium’ uranium material. The resulting half-life ratio T _1/2(²³⁸U)/T _1/2(²³⁵U) = 6.351±0.031 is in agreement with the commonly adopted half-life values determined by Jaffey et al.     

Radioactive series disequilibria in underground uranium deposits of the Singhbhum Shear Zone, Eastern India

Radionuclides of the ²³⁸U series (²²⁶Ra, ²¹⁰Pb, ²³⁴Th and ²³⁴U), ²³⁵U series (²²⁷Ac and ²³¹Pa) and ²³²Th series (²²⁸Th and ²²⁸Ra) series were measured by High Resolution Gamma Spectrometry system in twenty-five uranium ore samples from underground uranium deposits in the Singhbhum Shear Zone of Eastern India. The activity concentrations were observed to vary within a wide range in most of the deposits, as is the case in most rocks of crustal origin. The uranium ore from these deposits were not of high ore grade (U concentrations ranged from 0.015 to 0.082%). Activity ratios of key daughter–parent pairs from the decay chains, viz. ²²⁶Ra/²³⁸U, ²²⁶Ra/²¹⁰Pb, ²³¹Pa/²³⁵U, ²²⁷Ac/²³⁵U, ²³⁰Th/²³⁸U, ²³⁴U/²³⁸U, ²²⁶Ra/²³⁰Th and ²²⁸Th/²²⁸Ra indicated migration/accumulation of uranium and radium in some samples. The ²²⁶Ra/²³⁰Th ARs suggested that the deposits were not closed to groundwater movement for a maximum time period of 8ky. Thiel plot of the ²³⁴U/²³⁸U vs. ²³⁰Th/²³⁸U activity ratios indicated uranium accumulation and complex processes of uranium redistribution.     

Anomalous behaviour of uranium isotopes in backwater sediments of Zuari river

The surface leaching of the labile component of uranium has been carried out in estuarine sediments of Zuari river in Goa. The measurements of alpha activities of²³⁸U,²³⁵U and²³⁴U in the leachates indicated a remarkable anomaly between the activities of²³⁸U and²³⁴U. The activity ratios of²³⁴U/²³⁸U in these leachates have been found to be in the range of 1.10 to 1.14. However, the activity ratios of²³⁵U/²³⁸U have been found to be 0.045 which is close to that in natural uranium. It has also been observed that the anomaly between²³⁸U and²³⁴U exists only on the surface organic layers of the backwater sediments of the Zuari river.