Measurement Of 226Ra Research Articles

Gross Alpha-Particle Activity and High 226Ra Concentrations Do Not Correspond with High 210Po in the Atlantic and Gulf Coastal Plain Aquifers of the United States

210Po, which is of human-health concern based on lifetime ingestion cancer risk, is indirectly regulated in drinking water through the U.S. Environmental Protection Agency’s gross alpha-particle activity (GAPA) maximum contaminant level of 15 pCi/L (picocuries per liter). This regulation requires independent measurement of 226Ra for samples exceeding the GAPA screening level of 5 pCi/L. There is no such requirement for 210Po. Co-occurrence of 226Ra and 210Po, alpha-emitting 238U-decay-series progeny, might be helpful in locating high-210Po waters but is unverified. Relations among 210Po, 226Ra, and GAPA evaluated for samples from 257 public-supply wells from Coastal Plain aquifers showed that concentrations of 226Ra correlated with GAPA but neither correlated with 210Po concentrations. The highest concentrations of 226Ra and 210Po were found under differing geochemical conditions. The highest 226Ra occurred in low-pH oxidizing waters and in neutral-pH reducing waters, where geochemical conditions render Fe–Mn-hydroxide sorbents inefficient. 210Po was highest (10.1 pCi/L) in reducing waters with high pH (>7.5, which results from progressive cation exchange), where 226Ra was lowest─exchanged to clay minerals. Because 226Ra and 210Po did not co-occur, the GAPA screening might not be protective for 210Po. Independent 210Po analysis is prudent, especially where groundwater is reducing with high pH and low 226Ra concentrations.

Measurement of 226-Ra, 232-Th, 40-K and 137-Cs concentrations in sediment samples and determination of annual effective dose due to these radionuclides in vicinity of hot springs in Kerman Province

Measurement of 226-Ra, 232-Th, 40-K and 137-Cs concentrations in sediment samples and determination of annual effective dose due to these radionuclides in vicinity of hot springs in Kerman Province

Automated separation and measurement of 226Ra and trace metals in freshwater, seawater and fracking water by online ion exchange chromatography coupled with ICP-MS

An online solid-phase extraction method combined with ICP-MS was developed to separate and quantify low levels of 226Ra and other metals in drinking water, lake, river and sea water, and fracking fluids. A dual-column lab-on-valve and multi-syringe flow injection analysis (LOV-MSFIA) system was developed to provide precise measurement of 226Ra in samples with total dissolved solids (TDS) less than 2%. For samples with higher levels of TDS (up to 20%), a triple-column LOV-MSFIA system was developed, which used AG 50 W-X8 cation exchange, Sr spec andNobias Chelate resins. Compared to earlier automated systems for Ra analysis, the dual and triple column systems described here were optimized to accommodate smaller sample volumes, more precise flow control and lower limits of detection (LOD). The LOV-MSFIA system coupled with ICP-MS is a significant improvement over traditional methods for low level 226Ra measurements, which require extended sample holding and/or analysis time. External calibration and standard addition were used to quantify the concentration of Ra for the LOV-MSFIA system. After method optimization, LODs for 226Ra as low as 4.3 mBq L−1 (1.75 fg L−1) were obtained in different sample matrices. The concentrations of selected metals were also measured on the triple-column system, together with Ra, with a total online processing time of 28.5 min per sample. Thus, the online LOV-MSFIA system is shown to be a powerful tool for the rapid analysis of low levels of 226Ra, as well as other metals, in various types of aqueous samples.

Measurement of 226Ra, 232Th and 40K and the associated radiological hazards in Ponnai river sand, Tamilnadu, India using Gamma ray spectrometry

ABSTRACT River sand is a one of the important and commonly used building material in India and hence in the present study, activity concentration of natural radionuclides such as 226Ra, 232Th and 40 K have been measured in sand samples collected from Ponnai river, Tamilnadu using HPGe detector-based gamma ray spectroscopy. The measured activity concentrations vary from 13.30 to 54.83 Bq kg−1 with a mean value of 31.07 Bq kg−1 for 226Ra, from 26.15 to 245.33 Bq kg−1 with a mean value of 83.61 Bq kg−1 for 232Th, from 218.76 to 581.88 Bq kg−1 with a mean value of 416.36 Bq kg−1 for 40 K. These mean values of activity concentration of radionuclides have been compared with recommended limit and other similar work carried in the world. In order to assess the radiation associated with sands, radiological parameters such as air absorbed dose rate, annual indoor and outdoor effective dose rate, excess lifetime cancer risk, were calculated. The result shows that excess lifetime cancer risk (ELCR) for the indoor exposure varied from 0.775 × 10−3 to 3.216 × 10−3 with an average value of 1.440 × 10−3. An average ELCR for Ponnai river sand samples is slightly higher than the world average value of 1.16 × 10−3 mSv y−1. Finally, to assess the delivery of gamma radiation to organs, effective dose to body organ (Dorgn) was calculated for all river sand samples in the study area.

Determination of radon leakage from sample container for gamma spectrometry measurement of 226Ra

Gamma spectrometry is widely used for radionuclide activity measurement of environmental sample including 226Ra in soil because it is versatile, easy to implement, non-destructive, and relatively cheap compared to other methods. By gamma spectrometry, 226Ra can be determined directly using its energy peak of 186.2 keV or indirectly by its decay products which are in secular equilibrium with 226Ra, i.e. 214Bi and 214Pb. However, both methods have challenges where for direct measurement, interfering from 235U energy peak of 185.7 keV can add significant contribution to the 186.2 keV of 226Ra gamma peak while for indirect measurement using energy peaks of 214Bi and 214Pb, decay products of 222Rn gas, longer time (at least 21 days) for their equilibrium ingrowth is needed and radon tightness of sample container must be ensured. In some measurements, the equilibrium could not be reached due to radon leakage from sample container. Therefore, in this paper, the radon leakage fraction from three different sealing methods of Marinelli beaker used in soil activity measurement were studied using HPGe detector and radon accumulation chamber with RAD7. The three sealing methods were only lid without sealing (MB1), sealed with paraffin film (MB2), sealed with silicone glue and vacuumed plastic bag (MB3) and their leakage fractions were 53%, 30%, and negligible leakage, respectively. Significant radon leakage from MB1 and MB2 have caused underestimation of 226Ra activity concentration measured by indirect gamma spectrometry. The study result recommends using MB3 sealing method for gamma spectrometry measurement because it is simple and cheap and has negligible leakage, moreover, its vacuumed plastic bag facilitates visual inspection to possible radon leakage.

A Study of Chemical, Mineral Compositions (of Some Metals) and Natural Radioactivity in Porcelain and Ceramic Dinner Ware

Fifteen Porcelain and Ceramic Dinner Wares samples (collected from local commercial suppliers—Jeddah Saudi Arabia) were studied applying X-Ray Diffraction and Atomic Absorption techniques were used to study the Chemical, Mineral, Compositions Concentrations (of Some Metals). In addition, the Natural Radioactivity measurements of 226Ra, 232Th and 40K, was used by a high-purity germanium (HPGe) detector. X-ray diffraction results showed that the major mineral constituents of 15 samples were quartz (SiO2) (except one), minor and trace elements vary from sample to sample. Atomic absorption spectroscopy results of the concentrations for (Al, Pb, Bi, U, Th and K) in (ppm) showed that Al2O average was 10.3 (ppm) (10%) less than the acceptable value. PbO, its average was 1.65 ppm which was slightly greater than the allowed value 1.35 ppm. Bi concentrations for all samples were lower than (DL 238U, 232Th and 40 K were (83.83, 91.05 and 751.07) Bq/kg dry. The radium equivalent activity concentration Raeq (Bq/kg) (302.61) was less than recommended value (370), gamma dose rate D (nGy/h) average (140.15) was much higher than the recommended value (60) (UNSCEER). Deff (mSv/year) and Hix were below the published admissible limit ≤ 1 and the risk is negligible. This study offers needed information for consumers at exposure risk and is useful to be found in terms of radiation protection.

Distribution of natural radioactivity around mechanized and non-mechanized mining regions

This study was conducted to assess the radiological impacts of mining activities in mechanized and non-mechanized mining sites in order to build up database records for non-nuclear industries. Measurements of 226Ra, 226Th and 40K in 50 soil samples collected from these sites were carried out using gamma spectrometry system. The investigations showed that the highest concentrations of these radionuclides were 32, 37 and 648 Bq/kg, respectively . The average values in the mechanized region were 16 ± 7, 22 ± 9 and 366 ± 148 Bq/kg, respectively, while in non-mechanized region they were 9 ± 4, 12 ± 6 and 111 ± 68 Bq/kg, respectively. Spearman’s rank correlation test resulted in significant correlations (at 0.01 level) between 226Ra and 232Th (0.6) and 40K (0.8) in the mechanized region, while 232Th correlated with 40K (0.445) in the non-mechanized region. At 0.05 level, only 232Th is correlated with 40K in mechanized area (0.58). Between the two groups, only 40K in the mechanized area showed significant correlation to 232Th in the non-mechanized area (0.497) at 0.05 level. The 226Ra/232Th ratios were 0.88 ± 0.66 and 0.77 ± 0.23 in the two regions, while 226Ra/40K ratios were much lower than natural. This is attributed to weathering and metrological conditions rather than mining activity. Some radiological parameters were assessed displayed in general, significantly low values when compared with average global and recommended values. It can be concluded that both mechanized mining and non-mechanized mining do not significantly alter the levels of natural radioactive elements and do not give rise to a significant radiation exposure for the mining workers or population.

Determination of the thoron emanation coefficient using a powder sandwich technique

Thoron (220 Rn) is a natural radioactive gas, tasteless, odourless, colourless, undetectable without proper equipment. This gas is carcinogenic, just like radon (222 Rn) but due to the short half-life (55.6s) and a small amount in the environment, its share in the absorbed radiation dose is often neglected. However, in areas rich in thorium (232Th), the radiation dose from the thoron can be much larger and quite significant. The problem is to measure the concentration of the thoron due to its short decay time as well as the fact that it is alpha-emitting as radon. An even greater challenge is to determine the emanation coefficient for the thoron.The method used in this experiment was developed by S.D. Kanse based on the work of D.J Greeman and adapted to the equipment used in Laboratory of Radiometric Expertise IFJ PAN. In the technique used to determine the thoron emanation coefficient, a closed loop system is used in which thoron is pushed out by means of a flow system from the sample and measured by a AlphaGuad DF2000 detector that is adapted to determine concentration of this gas. A sample of the material is placed between 2 filters in the geometry of the sandwich. This arrangement ensures that the thickness of the powder sample is significantly less than the length of the thoron diffusion, thus avoiding significant loss of the thoron due to intergranular absorption and facilitates the complete removal of this gas escaping from the powder. Using this technique, it is important to determine the concentration of 226Ra and the 232Th, since for the AlphaGuard detector, the ratio between thoron and radon should not exceed 5:1 for proper determination of the thoron concentration. Measurements of 226Ra and 232Th activity were carried out using gamma spectroscopy (HPGe detector). It was examined how the type of filter and grain size of sample affects the obtained results.

High Throughput, Direct Determination of 226Ra in Water and Digested Geological Samples

A method was developed for direct measurements of 226Ra in water samples with triple quadrupole inductively coupled plasma mass spectrometry (ICP-QQQ). The limit of detection was 0.42 pg L-1226Ra (15 mBq L-1, 0.42 pCi L-1), which is compliant with the specifications for methods used for routine analysis of drinking water quality according to European and U.S. regulations. The use of N2O as reaction gas ensured that no separation before analysis was necessary. Water samples with high total dissolved solids (conductivity >100 mS cm-1) were also successfully analyzed after a simple dilution, yet the associated detection limit was higher (17 pg L-1, 0.61 Bq L-1, 16 pCi L-1). 226Ra content in soil and rock samples was determined with the same method after acid (HNO3 + H3PO4) digestion and dilution, resulting in a limit of detection of 0.75 ng kg-1 (27 Bq kg-1, 0.74 nCi L-1). Analysis of water samples was achieved within 2 min on a running instrument, while the preparation and analysis of 15 geological samples can be completed in 3 h. The key advantages of this direct analysis method are short preparation time, low labor intensity, low sample input (2 mL for water samples, 0.2 g for geological material), high sample throughput (2 min sample to sample, >150 samples measured in 8 h), and use of standard ICP-QQQ hardware. Overall, the proposed method offers a new opportunity for measuring a large number of samples with minimal effort and, in turn, for improving emergency preparedness, environmental monitoring, and data collection for environmental modeling.

Evaluation of different LSC methods for 222Rn determination in waters

Monitoring of 222Rn in drinking or surface waters, as well as in groundwater has been performed regularly in connection with geological, hydrogeological and hydrological surveys and health hazard studies. Liquid scintillation counting (LSC) is often preferred analytical method for 222Rn measurements in waters as it allows multiple-sample automatic analysis. LSC method implies mixing of water samples with organic scintillation cocktail, which triggers radon diffusion from the aqueous into an organic phase for which it has a much greater affinity, eliminating the possibility of radon emanation in that manner.The main aim of this paper is calibration of the liquid scintillation counter Qunatulus 1220™ for measuring of radon in water and evaluation of two different methods (one-phase and two-phase) in order to obtain the most suitable LSC technique for radon in water measurement. In this study four different scintillation cocktails were tested: one miscible (Ultima Gold AB) and three immiscible (High Efficiency Mineral Oil Scintillator, Opti-Fluor O and Ultima Gold F). Evaluation of presented methods was based on obtained detection efficiency and achieved Minimal Detectable Activity (MDA) values. Comparison of presented methods, accuracy and precision, as well as different scintillation cocktail's performance, was considered from results of measurements of 226Ra spiked water samples with known activity and environmental samples. LSC results were compared with the results of radon in water measurement obtained by alpha spectrometer RAD7. Calibration was done as a dependence of calibration factor (CF) from Pulse Shape Analysis (PSA).According to the obtained results, with proper adjustment of calibration parameters, both methods could be used for radon in water measurements. The obtained MDA values for all four scintillation cocktails are very low, less than 0.1 Bq l−1 for measuring time of 300 min.

Ra and Rn isotopes as natural tracers of submarine groundwater discharge in the patagonian coastal zone (Argentina): an initial assessment

Submarine groundwater discharge (SGD) is herein recognized as a significant pathway of material transport from land to the coastal SW Atlantic Ocean and thus, it can be a relevant factor affecting the marine biogeochemical cycles in the region. This paper focuses on the initial measurements of 226Ra, 228Ra and 222Rn made in Patagonia’s coastal zone of Chubut and Santa Cruz provinces (42°S–48°S, Argentina). 226Ra activity ranged from 2.9 to 73.5 dpm 100 L−1, and 228Ra activity ranged from 11.9 to 311.0 dpm 100 L−1 in groundwater wells. The radium activities found in Patagonia’s marine coastal regions and adjacent shelf indicate significant enrichment throughout the coastal waters. Groundwater samples presented the largest 222Rn activity and ranged from 2.66 to 1083 dpm L−1. Conversely, in the coastal marine environment, the 222Rn activity ranged from 1.03 to 6.23 dpm L−1. The Patagonian coastal aquifer showed a larger enrichment in 228Ra than in 226Ra, which is a typical feature for sites where SGD is dominant, probably playing a significant role in the biogeochemistry of these coastal waters.

Rapid method to determine 226Ra in steel samples

The rapid measurement of 226Ra in steel samples is very important in the event of a radiological emergency. 226Ra (T 1/2 = 1600 y) is a natural radionuclide present in the environment and a highly toxic alpha-emitter. Due to its long life and tendency to concentrate in bones, 226Ra ingestion or inhalation can lead to significant committed dose to individuals. A new method for the determination of 226Ra in steel samples has been developed at the Savannah River Environmental Laboratory. The new method employs a rugged acid digestion method that includes hydrofluoric acid, followed by a single precipitation step to rapidly preconcentrate the radium and remove most of the dissolved steel sample matrix. Radium is then separated using a combination of cation exchange and extraction chromatography, and 226Ra is measured by alpha spectrometry. This approach has a sample preparation time of ~ 8 h for steel samples, has a very high tracer yield (> 88%), and removes interferences effectively. A 133Ba yield tracer is used so that samples can be counted immediately following the separation method, avoiding lengthy ingrowth times that are required in other methods.

226Ra, 222Rn AND PERMEABILITY OF BELGIAN SOILS IN RELATION WITH INDOOR RADON RISK.

Knowing the concentration of 226Ra in soil and of 222Rn in soil gas is important for the analysis of indoor radon data and the prediction of radon-prone areas. Except for soil Rn in Ardenne, the data concerning these two radionuclides in Belgian soils are very scarce. In the context of Master theses and international courses, students made 92 measurements of 226Ra in soil samples, 105 of 222Rn in soil gas, and 74 of soil permeability, a significant addition to the existing similar data. The data are analysed in relation with soil texture, geological units and indoor radon risk. There is no clear correlation between radium in soil and indoor radon risk, the most important factor of risk being soil permeability.

Transit time of river water in the Bering and Chukchi Seas estimated from δ18O and radium isotopes

Seawater samples for the measurements of 226Ra, 228Ra and stable oxygen isotope (δ18O) were collected from the Bering and Chukchi Seas in the summer of 2014. The fractions of meteoric water (fMW) and sea-ice melted water (fSIM) were estimated based on the mass balance of salinity and δ18O with a three end-member mixing model. Our results showed that the average fMW increased northward from the Bering Basin to the Canada Basin while the fSIM distributed homogeneously. The lowest fMW and 228Ra/226Ra)A.R. values were found in the upper Bering Basin with little terrestrial input. The highest fMW but low 228Ra/226Ra)A.R. appeared in the northern Chukchi Sea and the Canada Basin, ascribing to the current-driven accumulation of freshwater and its long residence time. More abundant sea-ice melted water was found on the pack-ice edge, indicating the trap of earlier melted waters by the ice pack. Based upon the linear relationships between 228Ra/226Ra)A.R. and fMW in the Bering Shelf and the Chukchi Shelf, the transit time for the Pacific inflow was constrained. The transit time of river water from the Bering Shelf to the Chukchi Shelf was estimated as 0.2–4.4years with an average of 1.6±1.5years, while that from the Chukchi Shelf to the Canada Basin was 10.2–13.2years with an average of 11.8±1.1years. The spatial variation of the transit time was mainly affected by the current intensity. Our study highlights the importance of in-depth evaluation for the subarctic-arctic exchange.

Determination of 226Ra in solid samples of few milligrams after mineralisation and measurement by solid scintillation

A protocol is proposed for the measurement of 226Ra on 150 mg of solid sample without radiochemistry. To evaluate the performance of this method, standard samples were used and the results were in good agreement with reference values. The detection limit obtained is about 130 Bq kg−1 (dry weight) without mineralised solution concentration by evaporation. A concentration of the solution by 4 and/or an increase of sample mass by 4 in the case of microwave digestion system, allows achieving a detection limit of 30 Bq kg−1 (dry weight) and thus measuring 226Ra in most soils. This method could also be used for NORM sites on soil and sediment samples.

The behaviour of 226Ra in high-volume environmental water samples on TK100 resin

Accurate, low-level measurement of 226Ra in high volume water samples requires rapid pre-concentration and robust separation techniques prior to measurement in order to comply with discharge limits and drinking water regulations. This study characterises the behaviour of 226Ra and interfering elements on recently developed TK100 (Triskem International) extraction chromatography resin. Distribution coefficients over a range of acid concentrations are given, along with an optimised procedure that shows rapid pre-concentration and separation of 226Ra on TK100 resin is achievable for high volume (1 L) water samples without the need for sample pre-treatment.

Rapid determination of radium-224/226 in seawater sample by alpha spectrometry

A new radiochemical separation method has been developed for rapid determination of alpha-emitting radium isotopes in seawater samples. This method can be applied for the measurement of 226Ra in seawater samples when 224Ra is used as tracer for chemical recovery correction. Likewise, 226Ra can also be added as tracer for the determination of 224Ra in seawater sample. In the method, radium is first pre-concentrated with hydrous titanium oxide (HTiO) and is purified by combined anion/cation exchange column chromatographic separation. The radium in the eluate is then co-precipitated with HTiO, dissolved in 9 M H2SO4, and followed through a BaSO4 micro-precipitation step to prepare a thin-layer counting source to determine the activities of 224Ra/226Ra by alpha spectrometry. Replicate spike and blank samples were measured to evaluate the performance of the procedure. The minimum detectable activity concentration was determined to be 0.5 mBq·L−1 for 226Ra and 0.4 mBq·L−1 for 224Ra in 1 L of seawater sample with a counting time of 48 h. The method is a promising candidate for rapid measurement for alpha-emitting Ra isotopes in a large population of environment water samples.

Development of a method for rapid analysis of Ra-226 in groundwater and discharge water samples by ICP-QQQ-MS

A novel and rapid method has been developed for pre-concentration and measurement of 226Ra in groundwater and discharge water samples using the latest generation triple quadrupole inductively coupled plasma mass spectrometry (ICP-QQQ-MS). Cation exchange and extraction chromatography are capable of pre-concentration factors of ~200 based on 1L samples. The sensitivity and interference removal capability of ICP-QQQ-MS was assessed from spiked groundwaters, with the introduction of He collision gas required to minimise instrument background in high-matrix samples. The technique developed is potentially capable of detecting 226Ra activities as low as 5mBqL−1 when combined with pre-concentration prior to measurement.

On the direct measurement of 226Ra and 228Ra using 3M Empore™ RAD disk by liquid scintillation spectrometry

A study on the use of 3M Empore™ Radium RAD disk for the rapid and direct determination of 226Ra and 228Ra concentration in drinking water samples by means of liquid scintillation spectrometry is described. Three cocktails and several treatments were tested in order to improve the knowledge on the energy transfer between the alpha or beta—particle emissions of the isotopes fixed in the RAD disk and the cocktail. The sources of variability of this method were compared with the elution method, in which radium is stripped from de RAD disk and measured by liquid scintillation spectrometry using a Quantulus 1220™.

Validation of an efficiency calibration procedure for a coaxial n-type and a well-type HPGe detector used for the measurement of environmental radioactivity

To obtain reliable measurements of the environmental radionuclide activity using HPGe (High Purity Germanium) detectors, the knowledge of the absolute peak efficiency is required. This work presents a practical procedure for efficiency calibration of a coaxial n-type and a well-type HPGe detector using experimental and Monte Carlo simulations methods. The method was performed in an energy range from 40 to 1460keV and it can be used for both, solid and liquid environmental samples. The calibration was initially verified measuring several reference materials provided by the IAEA (International Atomic Energy Agency). Finally, through the participation in two Proficiency Tests organized by IAEA for the members of the ALMERA network (Analytical Laboratories for the Measurement of Environmental Radioactivity) the validity of the developed procedure was confirmed. The validation also showed that measurement of 226Ra should be conducted using coaxial n-type HPGe detector in order to minimize the true coincidence summing effect.