Determination Of 226Ra Research Articles

Determination of 226Ra in urine and water samples and sequential separation of 228Ra and 90Sr in drinking water

Determination of 226Ra in urine and water samples and sequential separation of 228Ra and 90Sr in drinking water

Simultaneous determination of 226Ra and 228Ra in food samples using liquid scintillation counting

The 228Ra and 226Ra isotopes of radium are significant contaminants in food, raising public concern because of their radiotoxicity. Several methods are available for determining 228Ra and 226Ra. However, the application of these procedures is not focused on food but only on water and environmental matrices. In this study, a cost-effective method for the simultaneous determination of 226Ra and 228Ra radioactivity in food samples using liquid scintillation counting was developed. The overall efficiencies of 226Ra and 228Ra in the food samples are 69.4–78.4% and 30.1–35.8%, respectively. The minimum detectable activities of 226Ra and 228Ra are 11.3 mBq/g and 33.4 mBq/g, respectively, in our food sample, obtained using a 1.0 g ash sample and 60 min of counting time. The method was validated using IAEA-certified reference materials and compared with data obtained using gamma spectrometry in tea, kelp, and oyster samples.

Validation of a newly adopted chemical method for determination of 226Ra and 228Ra activities in water and shrimp samples

Validation of a newly adopted chemical method for determination of 226Ra and 228Ra activities in water and shrimp samples

Fly ash sorbent modified with KMnO4 for the separation of important radionuclides

AbstractThe main aim of this work was to develop a suitable sorbent for the separation and determination of 226Ra through 133Ba (radio tracer) in water samples using fly ash sorbent. After the modification with KMnO4 the effects of pH, competing ions, the possibility of elution, and the effect of water volume were tested. As a suitable eluent 6 mol/L HCl was chosen, while the sorbent worked best at pH 6–8. The developed method is advantageous for minimizing the time required for separation, the volume of chemicals used, and the waste generated after separation.

Determination of 226Ra in environmental samples by alpha spectrometry: a new separation method based on the rapid co-precipitation of 226Ra with PbSO4

Determination of 226Ra in environmental samples by alpha spectrometry: a new separation method based on the rapid co-precipitation of 226Ra with PbSO4

Mobility, activity ratio significance and risk assessment of radionuclides in sandstone of Magharet El Miah, Southwestern Sinai, Egypt

Sedimentary rocks of Magharet El Miah were radiometrically analyzed for determination of radionuclides 238U, 232Th, 226Ra and 40K activity concentrations. The U-content and Th/U ratio in these rocks illustrated poor weathering and rapid deposition of rock detritus. Preferential dissolution of 234U due to α-decay related processes and its re-adsorption and precipitation are responsible for the observed radioactive disequilibrium in 234U/238U of Magharet El Miah sandstone. 234U mobilization could be related to the effect of surficial or underground water. 226Ra/238U disequilibrium could be revised to the difference in the geochemical characteristics of the two isotopes. 230Th/238U activity ratios were lower than unity in all samples (10 samples) except sample number 1, suggesting selective uranium accumulation in most samples or 230Th leaching by acidified water where the rocks contain high sulpher contents. Many of the 238U/235U activity ratios were shifted from the natural ratio due to the changes in redox conditions that leads to fractionation of higher isotope from lighter one. The plotted value of 234U/238U and 230Th/238U illustrated that the U-accumulation occurred in the period from <6 × 104–105 years. The studied sandstone had higher values for uranium (95.4 ± 7.1 to 130.3 ± 12.3 Bq.kg−1), thorium (65.8 ± 4.2 and 78.4 ± 6.7 Bq.kg−1) and radium (68.2 ± 4.4 and 80.3 ± 9.1 Bq.kg−1) but lower for potassium (38.4 ± 1.2 and 54.2 ± 2.3 Bq.kg−1) in comparison with international permissible levels. All the estimated environmental hazard indices illustrated that most samples lied in the permissible level ranges. Cluster analyses indicated that the main environmental health hazard parameters exist due to the activity concentrations of 238U and 226Ra.

Natural radionuclides in thermal mineral springs in Edipsos Greece.

Natural thermal and mineral therapeutic springs exist all over Greece. A radiological survey has been carried out in the municipality of Edipsos to study the naturally occurring alpha emitter radionuclides, 226Ra and the uranium isotopes. Thirteen thermal spring water samples and six tap water samples which were collected from five locations in the municipality of Edipsos, were analysed and measured by a-spectrometry. The obtained results show that 238U activity varies between 2.8±0.3 and 65.0±5.3 mBq/L in hot springs and between 2.70±0.35 and 10.6±0.9 mBq/L in tap water samples. The 234U/238U activity ratio lying between 1.12±0.17 and 2.12±0.30 indicates enrichment in the 234U concentration that can be explained through its ability to be easily leached from mineral surfaces. The 226Ra activity concentration varies between 3.5±0.4 and 1470±127 mBq/L in hot springs and between 6.5±0.9 and 28.2±2.8 mBq/L in tap water samples. Based on these results the estimated doses in this study are below the recommended dose of 1mSv/y. Highlights A radiological survey was carried out in the thermal springs of Edipsos, one of the most popular spa towns in Greece. Determination of uranium isotopes and 226Ra via a-spectrometry was performed. Low uranium content was a common characteristic for all the samples.

Radiological and environmental hazards of granitic rocks in Wadi Faliq El Sahl and El Waar area, North Eastern Desert, Egypt

Chronologically, the main exposures in the study area include; tonalite, granodiorite, adamellite, Hammamat Sediments, monzogranite, syenogranite, rapakivi syenogranite, alkali feldspar granite and dykes. This work aims to determine the suitability of the granitic rocks for using as ornamental stones through detecting their radiological and ecological impacts. The studied samples were measured radiometrically by using Na-I detector for determination of 226Ra, 232Th and 40K concentrations. External hazard indices (Hex) in some samples are more than unity, also, the (Raeq) are higher than the exemption limits (370 Bq.kg−1) exceeds the upper limit of exposure. The hierarchical cluster analysis (HCA) was applied to investigate the correlation between the radionuclides and the corresponding radiological hazard variables. Based on the statistical analysis, 232Th and 226Ra mainly contribute to the radioactive risk of the studied rocks. Regarding ecological indices, 42.1% of younger granite samples have Pollution load index values greater than 1, indicating deterioration, while the majority of older granite samples are lower than 1 suggesting perfection samples. Where, some sample from the older granitoids and younger granites have many radiological and ecological parameters greater than the recommended international limits, so, these samples should not be used in construction for safety reasons.

Precise measurement of 226Ra/230Th disequilibria in deep-sea sediments by high-sensitivity ICP-MS

We describe a new method suitable for the precise and accurate determination of 226Ra in porewater and sediment samples using a single-collector sector field ICP-MS (ThermoFisher Element XR) equipped with an Apex-Q desolvation device and a high-sensitivity Jet-X interface. In combination with 230Th measurements in parallel sediment samples, this method allows precise and accurate quantification of the 226Ra/230Th disequilibria in surface sediment cores, thereby enabling the use of this isotope pair as a tracer of solute transfer across the sediment-water interface in the deep ocean. The method integrates a step of isotope dilution with 228Ra as an internal spike, a pre-concentration of Ra and Ba by MnO2 precipitation, and an efficient separation of Ra from other undesirable elements using a cation exchange resin and a Triskem Sr-spec resin. With the inclusion of one or two additional cation resin columns and the use of up to 16 bed-volumes of a lower molarity (1.7 M) HCl eluent, our procedure eliminates the complicated matrix effects persistently encountered in previous studies, and provides a highly purified solution suitable for 226Ra measurement using an Element XR ICP-MS apparatus. Consequently, we are able to determine the activity of 226Ra in ∼20–50 ml of porewater or 100 mg of sediment with an internal precision of ∼1.0% and an accuracy of ∼99.2%. The precise measurements of porewater and solid phase 226Ra in a sediment core from the North Pacific Ocean allowed the distribution coefficient (Kd) of 226Ra to be constrained tightly within a range of 4700–11,600 ml g−1. Moreover, with the aid of a one-dimensional exchange model, the combination of the 226Ra and 230Th measurements allowed us to estimate a 226Ra flux of 1140 ± 20 dpm m−2 y−1 from the sediment core.

Determination of Natural Radionuclides (Ra-226, Po-210, Ra-228 and K-40) and Cs-137 in Fish Consumed in the City of São Paulo

The aim of the study was to determine the activity concentration of the natural radionuclides (226Ra, 210Po, 228Ra and 40K) and artificial radionuclide 137Cs in the muscle of the marine fish species most consumed in the city of São Paulo and to evaluate the annual effective dose due to the consumption of the fish. Samples were collected in the supermarket chain Extra and Carrefour and in the distribution center CEAGESP. Six fish species were selected among the most available and consumed in São Paulo city: anchovy, tuna, dogfish, croaker, hake and sardine. After the sample preparation procedures, the determination of 226Ra, 228Ra, 40K and 137Cs was carried out by gamma spectrometry and the determination of 210Po by alpha spectrometry. The results obtained for all the species studied are below the limits adopted by the Brazilian Standards for 137Cs and, therefore, their consumption offers no risk due to the ingestion of this radionuclide. The concentration obtained for the radionuclides 226Ra, 210Po, 228Ra and 137Cs in the fish samples analized are low and of the same order of magnitude as data from literature. The results obtained for the doses, for all the species studied, showed that their consumption offers no risk of exposure due to the ingestion of the analyzed radionuclides.

The dynamics of the detection of 226Ra in water by scintillation counting in nonequilibrium conditions

The conventional methods for the 226Ra determination by liquid scintillation counting require to attain secular equilibrium between 226Ra and 222Rn prior to the counting. This study describes a method that allows the immediate counting of a sample after the dissolution of Ba(Ra)SO4 in EDTA. This results from a detailed modelling of the activity of the parent 226Ra and its daughters in both the aqueous and organic scintillator phases. This methodology was tested on standard solutions of 226Ra showing promising results.

Improvements in the radiochemical method for separating 226Ra in solid samples through coprecipitation with BaSO4

The aim of this work was to improve the commonly used method for 226Ra determination in water and to establish its application in solid samples. This method is based on the coprecipitation of Ra with BaSO4 and gross alpha counting of the precipitate. An exhaustive study of the coprecipitation behaviour of the most abundant cations present in solid samples was performed to avoid incorrect radiochemical yields. As a result, it was considered necessary to introduce two new purification steps into the conventional method. Likewise, two nuclides, 241Am and 226Ra, were compared to obtain the mass efficiency curve given their different behaviour in the coprecipitation process. While Ra behaves similarly to Ba, Am coprecipitates, forming mixed crystals that may behave differently in the self-absorption process. The influence of the cations on the chemical yield with no precipitate purification was: Sr2+≫Fe3+>Mg2+≈Ca2+>K+≈Na+. The method was successfully applied to soil, sediment, and plant ash samples.

Radiation exposure in a region with natural high background radiation originated from rare earth element deposits at Bat Xat district, Vietnam.

Surface deposits of rare earth element (REE) were identified in the Bat Xat district, Northern Vietnam. As the area is inhabited, an in-depth investigation was carried out to assess the radioactivity levels and to evaluate the radiation exposure and radiological risks for the population. Samples of REE ore, soils, water and several foods locally produced were collected and analyzed by gamma spectrometry for determination of 232Th, 226Ra, and 40K. Radon (222Rn and 220Rn) measurements were carried out in dwellings at the villages located near by the REE deposit area, and in Hanoi for comparison. Based on the measured radionuclide concentrations, several radiological parameters were calculated to evaluate the radiological risks for the population and to compare with worldwide values. Results indicate that the representative person of the most exposed group living near the REE deposits may receive a total annual effective dose as high as 37.9 ± 10.6mSv, i.e., approximately 16 times the world average dose of 2.4mSv y-1. Consequently, this area should be considered a high background radiation area. Exposure to external radiation and internal radiation from ingestion and inhalation of radionuclides were assessed separately. Radon inhalation contributed to approximately 70% of the total annual effective dose, with both radon isotopes contributing significantly, while the ingestion of local foods and water gave minor contributions to the total effective dose. Several measures were considered to improve the radiation safety and recommendations are given to relocate the most exposed members of the population.

Rapid sequential determination of 222Rn and 226Ra in drinking water by liquid scintillation counting

Since daily drinking water is one of the major source for the ingestion of radiotoxic 222Rn and 226Ra, the demand for a simple method to determine these two radionuclides has significantly increased. In the present study, a rapid, simple sequential analysis method for determining 222Rn and 226Ra in drinking water using a liquid scintillation counter was developed. The method employs solvent extraction and correction equations for the effect of native 222Rn for 226Ra analysis. Validation and examination of applicability for drinking water analysis were conducted using 222Rn-injected water and 226Ra standard source. Minimum required counting times for examining drinking water on Quantulus 1220 and Hidex 300SL were estimated via minimum detectable activity depending on the counting time. In addition, the correction method, including an equation for reducing analysis time by more than 10 days, was suggested based on the analytical results for different elapsed times between sampling and measurement.

Cherenkov Radiation Detection on a LS Counter for 226Ra Determination in Water and Its Comparison with Other Common Methods.

Reliable determination of 226Ra content in drinking water, surface water and groundwater is required for radiological health-risk assessment of populations and radiation-dose calculations after ingestion and inhalation. This study aimed to determine 226Ra presence in the untreated water samples on a liquid scintillation counter via Cherenkov radiation detection. Cherenkov counting is a faster, simpler, less expensive technique than other commonly used methods for 226Ra determination. Step-by-step optimization of this technique on the Quantulus detector is presented in this paper. Improvement of detection limit/efficiency in the presence of sodium salicylate was investigated in this study. The main parameters of the method obtained were detection efficiency 15.87 (24)% and detection limit 0.415 Bq/L achieved for 1000 min of counting in 20 mL of sample volume. When 1 g of sodium salicylate was added, efficiency increased to 38.1 (5)%, with a reduction in the detection limit to 0.248 Bq/L for 500 min of counting. A satisfactory precision level of Cherenkov counting was obtained, the results deviating between 5% and 20% from reference values. The precision and accuracy of the Cherenkov counting technique were compared to liquid scintillation counting (EPA Method 913.0 for radon determination) and gamma spectrometry (the direct method for the untreated water samples on HPGe spectrometer). An overview of the advantages/disadvantages of each technique is elaborated in this paper.

Determination of 40K, 226Ra and 228Ra concentrations with dose rates in crayfish from Ode Omi River and radiological implications to the consumers

Natural radionuclides such as 40K, 226Ra and 228Ra are found naturally in water and sediments of rivers, likewise in soils. They are transferred to aquatic animals through ingestion. Radioactivity concentrations and dose rates of 40K, 226Ra and 228Ra in crayfish species from Ode Omi River in coastal region, Ogun State Southwest of Nigeria were determined by gamma spectrometry using NaI (TI) detector coupled with a pre-amplifier base to a multiple channel analyzer (MCA). 15 samples of crayfish were collected. Cherax tenuimanus had the highest mean concentration and dose rate of values 106.87 ± 9.11 Bq kg–1 and 0.00960 mGy hr–1 respectively for 40K. Moreso, for 226Ra, Cherax quadricarinatus had the highest mean concentration and dose rate of values 2.57 ± 0.82 Bq kg–1 and 4.50 x 10–7 mGy hr–1 respectively. Concerning228Ra, Astacopsis gouldi had the highest mean concentration and dose rate of values 5.23 ± 0.46 Bq kg–1 and 5.86 x 10–13 mGy hr–1, respectively. The average dose rate of the radionuclides in all the crayfish was calculated to be 4.62 x 10 ̶ 3 mGy hr–1 which was below the 0.4 mGy hr–1 limit recommended. The average annual committed effective dose and average excess lifetime cancer risk of all the radionuclides to the consumers were 0.0807 mSv yr–1 and 0.589 x 10–4, respectively, which were below global limits of 1.0 mSv yr–1 and 0.29 x 10–3, respectively, therefore, the ingestion of these natural radionuclides could not pose any radiological health hazards to the aquatic animals, likewise man the consumers.&#x0D; Keywords: Radionuclide concentration, Dose rate, Cancer Risk.

The analysis of 226Ra in 1‐liter seawater by isotope dilution via single‐collector sector‐field ICP‐MS

AbstractThe precise determination of radium‐226 (226Ra) in environmental samples is challenging due to its low concentration. Seawater typically contains between 0.03 and 0.1 fg g−1 226Ra. Thus, this work addresses the need for an easy and precise methodology for 226Ra determination in seawater that may be applied routinely to a large number of samples. For this reason, a new analytical approach has been developed for the quantification of 226Ra in seawater via inductively coupled plasma mass spectrometry (ICP‐MS). Analysis by single collector sector‐field ICP‐MS was shown to be convenient and reliable for this purpose once potential molecular interferences were excluded by a combination of chemical separation and intermediate mass resolution analysis. The proposed method allows purification of Ra from the sample matrix based on preconcentration by MnO2 precipitation, followed by two‐column separation using a cation exchange resin and an extraction chromatographic resin. The method can be applied to acidified and unacidified seawater samples. The recovery efficiency for Ra ranged between 90% and 99.8%, with precision of 5%, accuracy of 95.7% to 99.9%, and a detection limit of 0.033 fg g−1 (referring to the original concentration of seawater). The method has been applied to measure 226Ra concentrations from the North Sea and validated by analyzing samples from the central Arctic (GEOTRACES GN04). Samples from a crossover station (from GEOTRACES GN04 and GEOTRACES GN01 research cruises) were analyzed using alternative methods, and our results are in good agreement with published values.

Occurrence of 222Rn and 226,228Ra in underground water and 222Rn in soil and their mutual correlations for underground water supplies in southern Greater Poland

European Union Council Directive 2013/51/EURATOM recently sets out so-called indicator parameters for: radon, tritium and indicative dose of water intended for human consumption. The aim of this research was to elaborate an effective procedure for determination of radon and radium 226,228Ra isotopes (which are potentially the main contributors to the internal dose from drinking and cooking water) and to find the possible relationships between these radionuclides in underground water reservoirs and 222Rn concentration in the soil gas in their vicinity. The research was performed by applying a non-volatile and water-immiscible scintillation cocktail based on a pure diisopropylnaphthalene (Ultima Gold F: UGF), which allow for efficient radon extraction from 0.5 dm3 of water samples to 20 cm3 of scintillation phase and its direct determination with a detection limit of 5 × 10–3 Bq dm−3. The further preliminary concentration of 3 dm3 of crude water samples by evaporation to 0.5 dm3 samples led to the removal of all unsupported 222Rn activity and allowed the 226Ra determination via equivalent 222Rn detection after one-month samples storage using a low-background Triathler liquid scintillation counter in the α/β separation counting mode. Together with determination of 226Ra isotope in water samples, the simultaneous measurements of 228Ra and 222Rn radionuclides concentrations in water as well as 222Rn activity in the soil gas around the water supply sites were performed. The achieved limit of 226Ra detection was at a very low level of 10–3 Bq dm−3. The measured values of 226Ra concentration in 50 public underground water supply units for the Kalisz district of Poland were relatively low and ranged from below detection limit to 28.5 × 10–3 Bq dm−3 with arithmetic mean and median values of 12.9 and 12.2 × 10–3 Bq dm−3, respectively. Weak correlations were observed between activity concentrations of 226Ra and 222Rn in the crude water samples (R2 = 0.31) and 222Rn in water and its concentration in the nearby soil gas (R2 = 0.48).

Determining the Solubility of RaF2 in Water

The solubility of radium fluoride in water was determined. Radium was purified by the chromatographic method with a BioRad AG-50×8 (NH4+) sorbent (200–400 mesh). The precipitation was performed by addition to an aqueous solution of purified Ra(NO3)2 an alcoholic solution of NH4F. The resulting precipitate was washed with ethanol and dried in air. To a dry RaF2 was added twice-distilled water, and the mixture was kept for 24 h under thermostating and agitation until a precipitate–solution equilibrium was attained. Aliquots were taken from the mother liquor for an alpha-spectrometric determination of 226Ra. The solubility in water was 0.763 ± 0.153 g per 100 g of the solution. Additionally, the solubility of radium fluoride in ethanol was found to be ~7.4 ×10–5 g per 100 g of solution.

Physico-chemical conditions controlling the radionuclides mobilisation in various granitic environments

ABSTRACT Nine samples were chemically characterized and radiometrically analyzed for determination of 234U, 238U, 235U, 230Th, 232Th, 226Ra and 40K by γ-ray spectrometer Hyper Purity Germanium (HPGe detector). 238U activity concentrations reach up to 79.78 Bq Kg-1in the altered granites, 1714.11 and 2223.48 Bq Kg-1in the episyenite and pegmatite. Average 234U activity concentrations in the altered granite is 59.26 Bq Kg-1, between 175.88-543.47 Bq Kg-1and 48.19-1102.88 Bq Kg-1in the episyenite and pegmatite, respectively. 232Th activity concentrations vary between 14.16-1024.8 Bq Kg-1in the episyenite, 11.46-240.27 in the pegmatite and reach up to 201.45 Bq Kg-1in the altered granites. 40K activity concentrations range between 4.42-9.15, 2.76-7.34 and 2.68-9.94 Bq Kg-1in the altered granite, episyenite and pegmatite, respectively. 235U activity concentration ranges between 3.74–2.56, 12.45-78.86 and 0.58-102.34 Bq Kg-1 in the altered granite, episyenite and pegmatite, respectively. The studied altered granite, episyenite and pegmatite samples have relatively higher values than recorded in the international standards with the exception of potassium which has lesser amounts. It is demonstrated that pH changes, oxidation-reduction conditions, mineralogical constituents, in addition to alteration processes in these variable granitic environments were the main factors controlling uranium mobilization according to valid processes. The difference in alteration processes and La/Y ratio clarified the presence of more than one event of uranium accumulation and/or leaching in these rocks as confirmed by the presence of uranium accumulation and uranium vacant occurrences. Also, the isotopic ratios of uranium as 238U/235U,234U/235U, 234U/ 238U, 226Ra/ 238U,226Ra/ 230Th, 210Pb/ 226Ra, 230Th/ 238U, 230Th/ 234U with major, trace and rare earth elements were also affected by physico-chemical conditions changes. The present study shows that the samples of episyenite and pegmatite have been affected by leaching-accumulation events in the period from (1 × 105 to ˃2 × 105years).