Radium Content Research Articles

Measurement of Radium Concentration and Radon Exhalation Rates of Soil Samples Collected From Selected Area of Basrah Governorate, Iraq Using Plastic Track Detectors

Measurement of Radium Concentration and Radon Exhalation Rates of Soil Samples Collected From Selected Area of Basrah Governorate, Iraq Using Plastic Track Detectors

Natural Radionuclides and Radon Exhalation Rate in the Soils of Cauvery River Basin

In this study, systematic measurement of activity concentrations of 40K, 226Ra, and 232Th and radon exhalation rate has been done in soil samples of Cauvery River environment. The activity was measured using HPGe gamma-ray spectrometer, and the mean values of 40K, 226Ra, and 232Th in the soil samples were found to be 182 ± 4, 34 ± 2, and 19 ± 1 Bq kg−1, respectively. The radon exhalation rate was measured by “Can technique” using SSNTD (LR-115) films. The mean values of radium concentration, surface exhalation, and mass exhalation rate were found to be 118.95, 293.61, and 108.53 mBq kg−1 h−1, respectively. The radiological hazard indices due to natural radioactivity were calculated and compared with international recommended values, which are lower than the recommended level. The radon exhalation rate is lower than the recommended level.

Radon-222 and radium-226 occurrence in water: a review

Abstract A total of 2143 dissolved radon-222 and radium-226 activity concentrations measured together in water samples was compiled from the literature. To date, the use of such a large database is the first attempt to establish a relationship for the 226 Ra– 222 Rn couple. Over the whole dataset, radon and radium concentrations range over more than nine and six orders of magnitude, respectively. Geometric means yield 9.82±0.73 Bq l −1 for radon and 54.6±2.7 mBq l −1 for radium. Only a few waters are in 226 Ra– 222 Rn radioactive equilibrium, with most of them being far from equilibrium; the geometric mean of the radium concentration in water/radon concentration in water ( C Ra / C Rn ) ratio is estimated to be 0.0056±0.0004. Significant differences in radon and radium concentrations are observed between groundwaters and surface waters, on the one hand, and between hot springs and cold springs, on the other. Within water types, typical ranges of radon and radium concentrations can be associated with subgroups of waters. While the radium concentration characterizes the geochemistry of the groundwater–rock interaction, the radon concentration, in most cases, is a signal of non-mobile radium embedded in the encasing rocks. Thus, the 226 Ra– 222 Rn couple can be a useful tool for the characterization of water and for the identification of water source rocks, shedding light on the various water–rock interaction processes taking place in the environment.

Natural Radioactivity at the Sin Quyen Iron-Oxide-Copper-Gold Deposit in North Vietnam

The field radiometric and laboratory measurements were performed at the Sin Quyen copper deposit in North Vietnam. The field gamma-ray spectrometry indicated the concentration of uranium ranging from 5.5 to 87 ppm, thorium from 5.6 to 33.2 ppm, and potassium from 0.3 to 4.7%. The measured dose rates ranged from 115 to 582 nGy/h, the highest doses being at the copper ore. Concentrations in the solid samples were in the range of 20–1700 Bq/kg for uranium, 20–92.7 Bq/kg for thorium, and 7–1345 Bq/kg for potassium. The calculated doses were from 22 to 896 nGy/h; both measured and calculated dose rates are mostly related to uranium. Concentrations of radium in water samples were below 0.17 Bq/L. Uranium in water samples was significantly higher than the hydrogeological background; the maximum of 13 Bq/L was at the waste zone pool, but neither radium nor uranium were present in tap water. Radon concentration in the dwelling air was from 42 to 278 Bq/m3 for 222Rn and from 8 to 193 Bq/m3 for 220Rn. The estimated committed dose rates were principally related to 222Rn concentration and ranged from 1.1 to 8.1 mSv/y.

Effective radium-226 concentration in rocks, soils, plants and bones

Abstract Effective radium-226 concentration, EC Ra , is the product of radium activity concentration, C Ra , multiplied by the emanation coefficient, E , which is probability of producing a radon-222 atom in the pore spaces. It is measured by accumulation experiments in the laboratory, achieved routinely for a sample mass >50 g using scintillation flasks to measure the radon concentration. We report on 3370 EC Ra values obtained from more than 11 800 such experiments. Rocks ( n =1351) have a mean EC Ra value of 1.9±0.1 Bq kg −1 (90% of data in the range 0.11–35 Bq kg −1 ), while soils ( n =1524) have a mean EC Ra value of 7.5±0.2 Bq kg −1 (90% of data between 1.4 and 28 Bq kg −1 ). Using this large dataset, we establish that the spatial structure of EC Ra is meaningful in geology or sedimentology. For plants ( n =85), EC Ra is generally <1 Bq kg −1 , but values of larger than 10 Bq kg −1 are also observed. Dedicated experiments were performed to measure emanation, E , in plants, and we obtained values of 0.86±0.04 compared with 0.24±0.04 for sands, which leads to estimates of the radium-226 soil-to-plant transfer ratio. For most measured animal bones ( n =26), EC Ra is >1 Bq kg −1 . Therefore, EC Ra appears essential for radon modelling, health hazard assessment and also in evaluating the transfer of radium-226 to the biosphere.

Microbially mediated barite dissolution in anoxic brines

Fluids injected into shale formations during hydraulic fracturing of black shale return with extraordinarily high total-dissolved-solids (TDS) and high concentrations of barium (Ba) and radium (Ra). Barite, BaSO4, has been implicated as a possible source of Ba as well as a problematic mineral scale that forms on internal well surfaces, often in close association with radiobarite, (Ba,Ra)SO4. The dissolution of barite by abiotic processes is well quantified. However, the identification of microbial communities in flowback and produced water necessitates the need to understand barite dissolution in the presence of bacteria. Therefore, we evaluated the rates and mechanisms of abiotic and microbially-mediated barite dissolution under anoxic and hypersaline conditions in the laboratory. Barite dissolution experiments were conducted with bacterial enrichment cultures established from produced water from Marcellus Shale wells located in northcentral Pennsylvania. These cultures were dominated by anaerobic halophilic bacteria from the genus Halanaerobium. Dissolved Ba was determined by ICP-OES and barite surfaces were investigated by SEM and AFM. Our results reveal that: 1) higher amounts of barium (up to ∼5 × ) are released from barite in the presence of Halanaerobium cultures compared to brine controls after 30 days of reaction, 2) etch pits that develop on the barite (001) surface in the presence of Halanaerobium exhibit a morphology that is distinct from those that form during control experiments without bacteria, 3) etch pits that develop in the presence of Halanaerobium exhibit a morphology that is similar to the morphology of etch pits formed in the presence of strong organic chelators, EDTA and DTPA, and 4) experiments using dialysis membranes to separate barite from bacteria suggest that direct contact between the two is not required in order to promote dissolution. These results suggest that Halanaerobium increase the rate of barite dissolution in anoxic and high ionic strength solutions. Additionally, the increase in rate occurs without direct microbe-mineral contact suggesting that metabolites secreted by the bacteria may be responsible for promotion of dissolution. The findings of this study have implications for understanding barium cycling in marine/hypersaline environments, release of barium (and associated radium) from waste solids generated from energy and mining industries, as well as potential for developing new anti-scaling chemicals.

Radon exhalation from granite countertops and expected indoor radon levels

Radon (222Rn) exhalation rates from granite countertops were measured using a continuous radon monitor. The countertops could be separated in three groups according to radon their exhalation rates. However, even for a worst-case scenario (e.g. E ~ 1.10 Bq m−2 h−1, no air circulation and full tile home) the contribution to indoor radon concentration is estimated to be [Rn] < 100 Bq m−3. In addition, despite the uneven radium distribution in the granite slabs, there is significant correlation (r 2 = 0.50) between the measured radon levels and the radium content of the granites.

Influence of soil structure on the “Fv approach” applied to 238U and 226Ra

The soil-to-plant transfer factors were determined in a granitic area for the two long-lived uranium series radionuclides 238U and 226Ra. With the aim to identify a physical fraction of soil whose concentration correlates linearly with the plant concentration, the soil compartment was analyzed in various stages. An initial study identified the soil compartments as being either bulk soil or its labile fraction. The bulk soil was subsequently divided into three granulometric fractions consisting of: coarse sand, fine sand, and silt and clay. The soil-to-plant transfer of radionuclides for each of these three texture fractions was analyzed. Lastly, the labile fraction was extracted from each textural part, and the activity concentration of the radionuclides 238U and 226Ra was measured. In order to assess the influence of soil texture on the soil-to-plant transfer process, we sought to identify possible correlations between the activity concentration in the plant compartment and those found in the different fractions within each soil compartment. The results showed that the soil-to-plant transfer process for uranium and radium depends on soil grain size, where the results for uranium showed a linear relationship between the activity concentration of uranium in the plant and the fine soil fraction. In contrast, a linear relation between the activity concentration of radium in the plant and the soil coarse-sand fraction was observed. Additionally, the presence of phosphate and calcium in the soil of all of the compartments studied affected the soil-to-plant transfer of uranium and radium, respectively.

Measurement of the radon exhalation rate and effective radium concentration in soil samples of southern Sakarya, Turkey

In the present study, radon exhalation rates in terms of mass and area, as well as the effective radium concentration in soil samples collected simultaneously from different districts of southern Sakarya have been measured by Sealed Can technique using LR-115 type-II detectors. Mass and areal radon exhalation rates in soil samples vary from 35.76 ± 1.5 to 253.15 ± 3.8 mBqkg−1h−1with an average value of 112.53 ± 2.7 mBqkg−1h−1and 0.73 ± 0.2 to 5.18 ± 0.6 Bqm−2h−1with an average value of 2.30 ± 0.6 Bqm−2h−1, respectively. The effective radium content was found to vary in the range 3.77 ± 0.5 to 26.69 ± 1.3 Bqkg−1with an average value of 11.86 ± 0.9 Bqkg−1. The area exhalation rate was also used to calculate indoor radon concentration contributed by radon exhalation from soil, and to estimate annual effective dose equivalent. While the indoor radon concentration contributed by radon exhalation from soil varies from 2.93 ± 0.9 to 20.73 ± 2.3 Bqm−3with an average value of 9.22 ± 1.5 Bqm−3, the estimated effective dose equivalent varies from 0.09 to 0.61 mSvy−1with an average value of 0.27 mSvy−1.

Removal of Radium from Synthetic Shale Gas Brines by Ion Exchange Resin

Abstract Rapid development of hydraulic fracturing for natural gas production from shale reservoirs presents a significant challenge related to the management of the high-salinity wastewaters that return to the surface. In addition to high total dissolved solids (TDS), shale gas-produced brines typically contain elevated concentrations of radium (Ra), which must be treated properly to prevent contamination of surface waters and allow for safe disposal or reuse of produced water. Treatment strategies that isolate radium in the lowest volume waste streams would be desirable to reduce disposal cost and generate useful treatment by-products. The present study evaluates the potential of a commercial strong acid cation exchange resin for removing Ra2+ from high-TDS brines using fixed-bed column reactors. Column reactors were operated with varying brine chemistries and salinities in an effort to find optimal conditions for Ra2+ removal through ion exchange. To overcome competing divalent cations present in the b...

Measurement of radium-226 concentration and dose calculation of drinking water samples in Guilan province of Iran

Measurement of radium-226 concentration and dose calculation of drinking water samples in Guilan province of Iran

Preliminary assessment of uranium mining legacy and environmental radioactivity levels in Sabugal region, Portugal

An environmental radioactivity survey carried out in the Sabugal region, Portugal, showed enhanced radioactivity levels in surface water streams related to water discharges from old uranium mines. Water from irrigation wells in this region displayed variable radionuclide levels due to natural occurrence of radionuclides and to contamination by mine water drainage. Horticulture products grown near the uranium mine sites contained elevated radium (226Ra) concentrations, but lower concentrations of uranium and other radionuclides. Despite the relatively high radioactivity in irrigation water, the absorption and accumulation of radionuclides in agriculture products were limited. Nevertheless, taking into consideration the volume of uranium waste piles, it is considered as necessary to improving the management of mine wastes and mine drainage to prevent further increase of environmental radioactivity in the area. The assessment of environmental impact and radiation issues lasting from the past uranium mining shall be used as lessons to improving future mining activities.

Correlation analysis of the natural radionuclides in soil and indoor radon in Vojvodina, Province of Serbia

The most dominant source of indoor radon is the underlying soil, so the enhanced levels of radon are usually expected in mountain regions and geology units with high radium and uranium content in surface soils. Laboratory for radioactivity and dose measurement, Faculty of Sciences, University of Novi Sad has rich databases of natural radionuclides concentrations in Vojvodina soil and also of indoor radon concentrations for the region of Vojvodina, Northern Province of Serbia. In this paper we present the results of correlative and multivariate analysis of these results and soil characteristics in order to estimate the geogenic radon potential. The correlative and multivariate analysis were done using Toolkit for Multivariate Analysis software package TMVA package, within ROOT analysis framework, which uses several comparable multivariate methods for our analysis. The evaluation ranking results based on the best signal efficiency and purity, show that the Boosted Decision Trees (BDT) and Multi Layer Preceptor (MLP), based on Artificial Neural Network (ANN), are multivariate methods which give the best results in the analysis. The BDTG multivariate method shows that variables with the highest importance are radio-nuclides activity on 30 cm depth. Moreover, the multivariate regression methods give a good approximation of indoor radon activity using full set of input variables. On several locations in the city of Novi Sad the results of indoor radon concentrations, radon emanation from soil, gamma spectrometry measurements of underlying soil and geology characteristics of soil were analyzed in detail in order to verify previously obtained correlations for Vojvodina soil.

Assessment of radiation hazards due to exposure to radionuclides in marble and ceramic commonly used as decorative building materials in Egypt

The concentrations of 238 U (226Ra), 232Th, and 40K for the commonly used decorative building materials (15 marble and 15 ceramic) in Egypt were measured using gamma spectroscopy system. Radionuclides concentrations in marble samples were ranged from: ND to 49.92 ± 7.74 Bq kg−1 for 226Ra, 8.30 ± 1.70 to 119.52 ± 16.00 Bq kg−1 for 232Th, and 32.60 ± 4.25 to 2238.33 ± 242.66 Bq kg−1 for 40K while in ceramic samples the concentration ranged from: 28.42 ± 5.41 to 118.70 ± 20.34 Bq kg−1 for 226Ra, 30.65 ± 5.49 to 114.15 ± 18.78 Bq kg−1 for 232Th, and 389.54 ± 49.57 to 1069.83 ± 124.50 Bq kg−1 for 40K, respectively. These results imply that radium and thorium concentrations were below the worldwide recommended values but potassium was above the standard guideline. Radiological hazards indices of radium equivalent activity (Raeq), external and internal hazard indices: Hex and Hin, respectively, and annual effective doses of the investigated materials due to the presence of those radionuclides were calculated and had values less than the worldwide recommended values of 370 Bq kg−1, unity and 1 mSv y−1, respectively. Therefore, the studied types of marble and ceramic can be safely used as decorative building materials.

The detailed analysis of natural radionuclides dissolved in spa waters of the Kłodzko Valley, Sudety Mountains, Poland

A survey was conducted to measure natural radioactivity in spa waters from the Kłodzko Valley. The main goal of this study was to determine the activity concentration of uranium, radium and radon isotopes in the investigated groundwaters. Samples were collected several times from 35 water intakes from 5 spas and 2 mineral water bottling plants. The authors examined whether the increased gamma radiation background, as well as the elevated values of radium and uranium content in reservoir rocks, have a significant impact on the natural radioactivity of these waters.The second objective of this research was to provide information about geochemistry of U, Ra, Rn radionuclides and the radiological and chemical risks incurred by ingestion of isotopes with drinking water. On the basis of results obtained, it is feasible to assess the health hazard posed by ingestion of natural radioactivity with drinking waters. Moreover, the data yielded by this research may be helpful in the process of verification of the application of these waters in balneotherapy.In addition, annual effective radiation doses resulting from the isotopes consumption were calculated on the basis of the evaluated activity concentrations. In dose assessment for uranium and radium isotopes, the authors provided values for different human age groups. The obtained uranium content in the investigated waters was compared with the currently valid regulations concerning the quality of drinking water. Based on the activity concentrations data, the activity isotopic ratios 234U/238U, 226Ra/238U, 222Rn/238U, 222Rn/226Ra and the correlations between radionuclides content were then examined. In brief, it may be concluded on the basis of the obtained results that radon solubility is inversely proportional to radium and uranium dissolution in environmental water circulation. The presented study allows conclusions to be drawn on the radionuclide circulation among different environmental biota: from lithosphere through hydrosphere to biosphere.

Radiotoxicity risks of radium-226 (226Ra) on groundwater-based drinking at Dawaki, Kuje, Giri and Sabon-Lugbe area of Abuja, North Central Nigeria

In this study, 226Ra and heavy metal concentrations were studied to represent the radiotoxicity risk of groundwater of Abuja, North Central Nigeria. Groundwater samples were collected from five areas in Abuja, and measurements were taken by using inductively coupled plasma mass spectrometer. Radium (226Ra) concentrations were determined from 0.067 to 0.216 µg/L. The mean annual effective dose from the natural radionuclide of 226Ra for the inhabitants was estimated to be 2.2 × 10−5 mSv. In addition, life average daily dose and cancer mortality risk were calculated. As a result, radiological risks of 226Ra in groundwater are quite low, typically in the magnitude of 10−7 when compared with the international reference dose level.

Effective radium concentration in topsoils contaminated by lead and zinc smelters

Trace elements (TE) are indicative of industrial pollution in soils, but geochemical methods are difficult to implement in contaminated sites with large numbers of samples. Therefore, measurement of soil magnetic susceptibility (MS) has been used to map TE pollutions, albeit with contrasted results in some cases. Effective radium concentration (ECRa), product of radium concentration by the emanation factor, can be measured in a cost-effective manner in the laboratory, and could then provide a useful addition. We evaluate this possibility using 186 topsoils sampled over about 783km2 around two former lead and zinc smelters in Northern France. The ECRa values, obtained from 319 measurements, range from 0.70±0.06 to 12.53±0.49Bq·kg−1, and are remarkably organized spatially, away from the smelters, in domains corresponding to geographical units. Lead-contaminated soils, with lead concentrations above 100mg·kg−1 <3km from the smelters, are characterized on average by larger peak ECRa values and larger dispersion. At large scales, away from the smelters, spatial variations of ECRa correlate well with spatial variations of MS, thus suggesting that, at distance larger than 5km, variability of MS contains a significant natural component. Larger ECRa values are correlated with larger fine fraction and, possibly, mercury concentration. While MS is enhanced in the vicinity of the smelters and is associated with the presence of soft ferrimagnetic minerals such as magnetite, it does not correlate systematically with metal concentrations. When multiple industrial and urban sources are present, ECRa mapping, thus, can help in identifying at least part of the natural spatial variability of MS. More generally, this study shows that ECRa mapping provides an independent and reliable assessment of the background spatial structure which underlies the structure of a given contamination. Furthermore, ECRa may provide a novel index to identify soils potentially able to fix leached components.

Geographically weighted regression and geostatistical techniques to construct the geogenic radon potential map of the Lazio region: A methodological proposal for the European Atlas of Natural Radiation

In many countries, assessment programmes are carried out to identify areas where people may be exposed to high radon levels. These programmes often involve detailed mapping, followed by spatial interpolation and extrapolation of the results based on the correlation of indoor radon values with other parameters (e.g., lithology, permeability and airborne total gamma radiation) to optimise the radon hazard maps at the municipal and/or regional scale. In the present work, Geographical Weighted Regression and geostatistics are used to estimate the Geogenic Radon Potential (GRP) of the Lazio Region, assuming that the radon risk only depends on the geological and environmental characteristics of the study area. A wide geodatabase has been organised including about 8000 samples of soil-gas radon, as well as other proxy variables, such as radium and uranium content of homogeneous geological units, rock permeability, and faults and topography often associated with radon production/migration in the shallow environment. All these data have been processed in a Geographic Information System (GIS) using geospatial analysis and geostatistics to produce base thematic maps in a 1000 m × 1000 m grid format. Global Ordinary Least Squared (OLS) regression and local Geographical Weighted Regression (GWR) have been applied and compared assuming that the relationships between radon activities and the environmental variables are not spatially stationary, but vary locally according to the GRP. The spatial regression model has been elaborated considering soil-gas radon concentrations as the response variable and developing proxy variables as predictors through the use of a training dataset. Then a validation procedure was used to predict soil-gas radon values using a test dataset. Finally, the predicted values were interpolated using the kriging algorithm to obtain the GRP map of the Lazio region. The map shows some high GRP areas corresponding to the volcanic terrains (central-northern sector of Lazio region) and to faulted and fractured carbonate rocks (central-southern and eastern sectors of the Lazio region). This typical local variability of autocorrelated phenomena can only be taken into account by using local methods for spatial data analysis. The constructed GRP map can be a useful tool to implement radon policies at both the national and local levels, providing critical data for land use and planning purposes.

Artificial water sediment regulation scheme influences morphology, hydrodynamics and nutrient behavior in the Yellow River estuary

Summary Anthropogenic controls on water and sediment may play important roles in river system transformations and morphological evolution, which could further affect coastal hydrodynamics and nutrient behavior. We used geochemical tracers to evaluate the influence of an intentional large release of water and sediment during the so-called “Water Sediment Regulation Scheme” (WSRS) on estuarine morphology, hydrodynamics and nutrients in the Yellow River estuary, China. We discovered that there was a newly formed small delta in the river mouth after the 2013 WSRS. This new morphologic feature altered terrestrial material distribution patterns from a single plume to a two-plume pattern within the estuary. Our results show that the WSRS significantly influenced the study area in the following ways: (1) Radium and nutrient concentrations were significantly elevated (two to four times), especially along the two river outlets. (2) Estuarine mixing was about two times stronger during WSRS than before. Average aerial mixing rates before and during WSRS were 50 ± 26 km2 d−1 and 89 ± 51 km2 d−1, respectively. (3) Our data is consistent with P limitation and suggest that stoichiometrically based P limitation was even more severe during WSRS. (4) All river-derived nutrients were thoroughly consumed within one to two weeks after entry to near-shore waters. (5) The extent of the area influenced by terrestrial nutrients was two to three times greater during WSRS. Human influence, such as triggered by WSRS regulations, should thus be considered when studying biogeochemical processes and nutrient budgets in situations like the Yellow River estuary.

Effective radium concentration in agricultural versus forest topsoils

Effective radium-226 activity concentration (ECRa), the radon-222 source term, was measured in the laboratory with 724 topsoil samples collected over a ∼110 km2 area located ∼20 km south of Paris, France. More than 2100 radon accumulation experiments were performed, with radon concentration measured using scintillation flasks, leading to relative uncertainties on ECRa varying from 10% for ECRa = 2 Bq⋅kg−1 to less than 6% for ECRa > 5 Bq⋅kg−1. Small-scale dispersion, studied at one location with 12 samples, and systematically at 100 locations with three topsoils separated by 1 m, was of the order of 7%, demonstrating that a single soil sample is reasonably representative. Agricultural topsoils (n = 540) had an average (arithmetic) ECRa of 8.09 ± 0.11 Bq⋅kg−1, and a range from 2.80 ± 0.22 to 19.5 ± 1.1 Bq⋅kg−1, while forest topsoils (n = 184), with an average of 3.21 ± 0.14 Bq⋅kg−1 and a range from 0.45 ± 0.12 to 9.09 ± 0.55 Bq⋅kg−1, showed a clear systematic reduction of ECRa when compared with the closest agricultural soil sample. Large-scale organization of ECRa was impressive for agricultural topsoils, with homogeneous domains of several kilometers size, characterized by smooth variations smaller than 10%. These patches emerged despite heavy human remodeling; they are controlled by the main geographical units, but do not necessarily coincide with them. Valleys were characterized by larger dispersion and less organization. This study illustrates how biosphere and anthroposphere modify the soil distribution inherited from geological processes, an important baseline needed for the study of contaminated sites. Furthermore, the observed depletion of forest topsoils suggests an atmospheric radon signature of deforestation.