222Rn Measurements Research Articles

International intercomparison and quality assessment of passive and active 222Rn measuring devices in the Asia-Pacific region

Intercomparison exercise is an integral part of the quality assurance programmes in 222Rn measurements using active and passive devices. Ensuring the accuracy of data generated through measurements necessitates periodic performance checks. To achieve harmonization of methods, quantify biases and errors in measurements, and identify the reasons for discrepancies, there is a pressing need for periodic intercomparison exercises. To address this need of numerous laboratories, particularly in the Asia-Pacific region, a calibration facility for 222Rn measuring devices has been established at the Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, India. An international intercomparison exercise for the 222Rn measuring devices was conducted at this facility in the year 2022 with the participation of 10 laboratories from six countries. A total of 354 devices (comprising of both active and passive detectors) were subjected to intercomparison measurements by exposing them to three concentration levels: (5.97 ± 0.29) × 103 Bq m−3, (0.70 ± 0.09) × 103 Bq m−3 and (2.02 ± 0.20) × 103 Bq m−3 in separate experiments and the exposure durations were 7 days, 15 days, and 10 days respectively. The performance of each laboratory was evaluated following the criterion adopted by the International Atomic Energy Agency (IAEA) in its worldwide proficiency test programmes. This exercise brought out the fact that some of the laboratories need to improve their measurement practices to produce reliable data.

Radon and water geochemistry at the active Campi Flegrei volcano (Italy): The role of pore-water phenomena

This study provides new 222Rn measurements performed by RAD7 on 31 thermal waters from the Campi Flegrei caldera, the active volcanic-geothermal field close to Naples (Southern Italy). Waters sampled between 2021 and 2023 are characterized for physical parameters, major ions geochemistry and radium content. Rn contents from Somma-Vesuvius, Ischia and Vulcano volcanoes, together with the river plain north to the Campi Flegrei, were obtained for comparison. The Campi Flegrei caldera reaches the highest Rn concentrations respect to the other sites, varying from 0.03 ± 0.02 to ca. 1887 ± 13 Bq/L, although mostly are below 60 Bq/L. We detect a steady-state condition of constant temperature, facies and radon activity that characterizes most sites, with only minor impacts from seasonalilty and Weigel's effects. Just a small fraction of 222Rn derives from its 226Ra parent in solution, while radon activity in local waters is mainly due to emanation from the radium-containing rock reservoir. Our dataset proofs that radon couples with temperature, sulfate and CO2 in relations to rock-leaching and pore-water phenomena that proceed in the reservoir as it warms up and degasses. Rn and CO2 are decoupled in deeply and timely equilibrated geothermal fluids.Two main end-members, i.e., a low radioactive cold diluted and the Rn-richest hypersaline water from the deep geothermal reservoir are recognized; seawater contamination and heating over 70 °C play a major role in radon decrease.Related radium contents, physical parameters and major ions geochemistry are also presented for a comparison with published data.

Lithological Impact on Radon Levels: A Study of Indoor and Soil Gas Radon in the Centre Region of Cameroon

AbstractThe objectives of the current study are to carry out soil gas radon (Rn) measurements, to evaluate the total inhalation effective dose, to determine risk levels over the lithological formations of the study area. The behavior investigation of Rn activity concentration distributions in dwellings and soils, and soil Rn mapping were also conducted. Soil gas Rn measurements were made at 102 sampling points by Markus 10 instrument. This data was combined with previously reported results from 140 indoor Rn RADTRAK dosimeters to determine the total inhalation effective dose and to conduct a statistical analysis. Overall, the Rn activity concentrations in soil and dwellings range from 4 to 66 kBq m−3 and from 15 to 140 Bq m−3, with averages of 31 ± 15 kBq m−3 and 41 ± 24 Bq m−3 respectively. The corresponding total inhalation effective dose ranges from 0.35 to 3.53 mSv y−1, with a mean value of 1.37 ± 0.58 mSv y−1. For soil gas Rn, the chlorite schist lithology showed the highest average concentration level. Which could be justified by the possible presence, within chlorite minerals, highly emitting zones of alpha particles, leading to the formation of radioactive halos. Normal and high‐risk level of Rn were found for about 82% and 11% of the total area surveyed respectively. These findings highlight the need for preventive measure against Rn exposure in homes within the investigated areas. This study contributes valuable insights into Rn distribution patterns and risk assessment, offering a basis for targeted interventions in the region.

Ambient Radiological Condition around an Operating Uranium Mill Tailings Disposal Facility at Turamdih, India

AbstractLarge quantity of the feed forms part of the solid waste (tailings) slurry in the low grade uranium ore processing plant at Turamdih in Singhbhum region of Jharkhand, India. Coarser size fraction of this waste is used for backfilling of the underground uranium mines and fine fraction is discharged into an engineered impoundment system or tailings pond. Since inception of the discharges, field expeditions have been performed as part of the comprehensive radiological monitoring program for the facility. The monitoring program broadly consists of ambient gamma dose rate, atmospheric 222Rn and long lived alpha activity measurement around the facility and the estimation of radionuclide in diverse environmental matrices collected from the adjoining sites. Findings reflect that the radiological conditions are comparable to the pre-existing background level adjoining the tailings pond impoundment. Further, measurements for more than a decade confirm that the atmospheric radon concentration profile just a few meters beyond the embankment is indistinguishable from the background.

Assessing Light Non-Aqueous Phase Liquids in the Subsurface Using the Soil Gas Rn Deficit Technique: A Literature Overview of Field Studies

222Radon (Rn) was proposed in the late 1990s as a naturally occurring tracer for light non-aqueous phase liquids (LNAPLs) in the subsurface, due to its preferential partitioning behavior in the non-aqueous phase, resulting in a reduction in Rn activities in areas with LNAPLs in the subsurface compared to unimpacted areas (Rn deficit). The Rn deficit technique emerged as a cost-effective, non-invasive, and sustainable method to rapidly identify and quantify LNAPLs, for the characterization and monitoring of contaminated sites. This paper presents an overview of the technique and its field applications, with a specific focus on the use of the method in the vadose zone based on soil gas Rn measurements. Although various configurations have shown favorable outcomes, limitations persist in the application of the soil gas Rn deficit technique. Deep LNAPL contamination, soil matrix heterogeneity, and temporal variations in Rn emissions pose challenges to quantitative evaluations of LNAPL contamination. Recognizing these factors is crucial for site-specific assessments. This review aims to highlight both the strengths and limitations of the method, providing insights into potential areas for future research while acknowledging the positive outcomes achieved in different configurations over the past decades.

Two new 222Rn emanation sources – a comparison study

Abstract. More than 50 % of naturally occurring radiation exposure to the general public is due to the noble gas radon (222Rn) and its progenies, causing considerable health risks. Therefore, the European Union has implemented Council Directive 2013/59/EURATOM to measure 222Rn activity concentrations and to identify radon priority areas (RPAs) to specify areas where countermeasures are most needed. Although 222Rn measurements are far spread across Europe, traceability to the International System of Units (SI) is still lacking for radon activity concentrations below 300 Bq m−3. Consequently, measurement results cannot be reliably compared with each other. The European Metrology Research Programme for Innovation and Research (EMPIR) 19ENV01 traceRadon project aimed to address this issue and has developed two new 222Rn emanation sources, intended to be used as calibration standards for reference instruments. The goal of this paper is to investigate and compare the two sources to ensure their quality by comparing the calibration factors estimated from both sources for the same reference instrument. This was done for three reference instruments in total at two experimental sites. Differences in calibration factors for one reference instrument of up to 0.07 were derived. Despite the small differences between the calibration factors, all uncertainties are well within the intended target uncertainty of 10 % for k = 1.

Identifying 1-rectifiable measures in Carnot groups

Abstract We continue to develop a program in geometric measure theory that seeks to identify how measures in a space interact with canonical families of sets in the space. In particular, extending a theorem of M. Badger and R. Schul in Euclidean space, for an arbitrary locally finite Borel measure in an arbitrary Carnot group, we develop tests that identify the part of the measure that is carried by rectifiable curves and the part of the measure that is singular to rectifiable curves. Our main result is entwined with an extension of analyst’s traveling salesman theorem, which characterizes the subsets of rectifiable curves in R 2 {{\mathbb{R}}}^{2} (P. W. Jones, Rectifiable sets and the traveling salesman problem, Invent. Math. 102 (1990), no. 1, 1–15), in R n {{\mathbb{R}}}^{n} (K. Okikiolu, Characterization of subsets of rectifiable curves in R n {{\bf{R}}}^{n} , J. London Math. Soc. (2) 46 (1992), no. 2, 336–348), or in an arbitrary Carnot group (S. Li) in terms of local geometric least-squares data called Jones’ β \beta -numbers. In a secondary result, we implement the Garnett-Killip-Schul construction of a doubling measure in R n {{\mathbb{R}}}^{n} that charges a rectifiable curve in an arbitrary complete, doubling, locally quasiconvex metric space.

Degassing of soil gas radon and its implication to fault activity in the western margin of the Ordos Block, China

AbstractSoil gas radon (Rn) serves as an effective indicator for assessing fault activity in fault zones. Measurement of Rn degassing at the active faults was conducted twice in 2017 and 2018 to assess fault activity in the western margin of the Ordos block. The concentration and flux values of Rn ranged from 0.41 to 40.93 kBq m−3 and 5.17 to 140.33 mBq m−2 s−1, respectively. The compression of the Tibetan Plateau has led to higher Rn concentration and flux in the southern part compared with the northern part. The fault activity is evaluated by the index of IRn calculated from Rn concentrations. The Haiyuan arcuate tectonic region exhibited the most intensive fault activity, followed by the Yinchuan Basin and Jilantai‐Linhe Basin. These findings enhance our understanding of the relationship between fault activity and Rn emission and provide a significant geochemical reference for the fault activity.

Inter-Comparison of Radon Measurements from a Commercial Beta-Attenuation Monitor and ANSTO Dual Flow Loop Monitor

Radon (Rn) is a radioactive, colourless, odourless, noble gas that decays rapidly. It’s most stable isotope, 222Rn, has a half-life of around 3.8 days. Atmospheric radon measurements play an important role in understanding our atmospheric environments. Naturally occurring radon can be used as an atmospheric tracer for airmass tracking, to assist in modelling boundary layer development, and is important for understanding background radiation levels and personal exposure to natural radiation. The daughter products from radon decay also play an important role when measuring fine particle pollution using beta-attenuation monitors (BAM). Beta radiation from the 222Rn decay chain interferes with BAM measurements of fine particles; thus, some BAMs incorporate radon measurements into their sampling systems. BAMs are ubiquitous in air quality monitoring networks globally and present a hitherto unexplored source of dense, continuous radon measurements. In this paper, we compare in situ real world 222Rn measurements from a high quality ANSTO dual flow loop, dual filter radon detector, and the radon measurements made by a commercial BAM instrument (Thermo 5014i). We find strong correlations between systems for hourly measurements (R2 = 0.91), daily means (R2 = 0.95), hour of day (R2 = 0.72–0.94), and by month (R2 = 0.83–0.94). The BAM underestimates radon by 22–39%; however, the linear response of the BAM measurements implies that they could be corrected to reflect the ANSTO standard measurements. Regardless, the radon measurements from BAMs could be used with correction to estimate local mixed layer development. Though only a 12-month study at a single location, our results suggest that radon measurements from BAMs can complement more robust measurements from standard monitors, augment radon measurements across broad regions of the world, and provide useful information for studies using radon as a tracer, particularly for boundary layer development and airmass identification.

Measurement of 222Rn in ground water and NORMs in top soil in the environs of Rooppur Nuclear Power Plant site and associated health hazard

Measurement of 222Rn in ground water and NORMs in top soil in the environs of Rooppur Nuclear Power Plant site and associated health hazard

The calibration of transfer standards for the measurement of 222Rn at NIM

A high-purity germanium (HPGe) gamma-ray spectrometer and an Alpha-GUARD radon monitor are the activity and activity concentration transfer standards of 222Rn, respectively. The gaseous 222Rn standard source traceable to the NIM's absolute standardization apparatus of 222Rn was developed for calibrating these transfer standards. The calibration results of HPGe detector at three different distances show that the uncertainties of experimental efficiency are less than 0.77% (k = 1). Meanwhile, the Monte Carlo (MC) simulation was carried out at wider distances range for the HPGe calibration as well, and the deviation at same three distances between experiments and simulations results is within ±3.0%. The advantage of calibration using MC simulation and the possible reasons for the deviation were discussed in detail in this article. In addition, a reference activity concentration environment based on the gaseous 222Rn standard source was also developed to calibrate the radon monitor, and the typical uncertainty for calibration factor of Alpha-GUARD radon monitor could be reduced to 1.9% (k = 1).

Influence of humidity on activated carbon fabrics scheduled for use in high sensitivity radon detectors

The dependence of radon adsorption on the content of adsorbed water of activated carbon fabrics of ACC-5092-10 and ACC-5092-20 was studied experimentally. Specimens with different content of adsorbed water (from zero to saturation level) were coupled with alpha-track detector and exposed to reference 222Rn concentration. Both materials demonstrated different properties: Radon adsorption in ACC-5092-10 smoothly and monotonically decreases with the increase of adsorbed water and at saturation level it is lower by a factor of 2.5 as compared to the fully dehydrated material. In ACC-5092-20 clear break point was observed at water content of about 20% where radon adsorption sharply drops by a factor of 15. ACC-5092-10 was identified as a material that keeps its high radon adsorption ability even when saturated with water. Coupled with alpha-track detector it may be used for sensitive long-term measurements 222Rn measurements even at high levels of humidity.

Existence of nonminimal solutions to an inhomogeneous elliptic equation with supercritical nonlinearity

Abstract In our previous paper [K. Ishige, S. Okabe, and T. Sato, A supercritical scalar field equation with a forcing term, J. Math. Pures Appl. 128 (2019), pp. 183–212], we proved the existence of a threshold κ ∗ > 0 {\kappa }^{\ast }\gt 0 such that the elliptic problem for an inhomogeneous elliptic equation − Δ u + u = u p + κ μ -\Delta u+u={u}^{p}+\kappa \mu in R N {{\bf{R}}}^{N} possesses a positive minimal solution decaying at the space infinity if and only if 0 < κ ≤ κ ∗ 0\lt \kappa \le {\kappa }^{\ast } . Here, N ≥ 2 N\ge 2 , μ \mu is a nontrivial nonnegative Radon measure in R N {{\bf{R}}}^{N} with a compact support, and p > 1 p\gt 1 is in the Joseph-Lundgren subcritical case. In this article, we prove the existence of nonminimal positive solutions to the elliptic problem. Our arguments are also applicable to inhomogeneous semilinear elliptic equations with exponential nonlinearity.

Regional groundwater flow system characterization of volcanic aquifers in upper Awash using multiple approaches, central Ethiopia

ABSTRACT Characterization of the groundwater flow systems is important for sustainable water resource management decision-making. We have used vertical profiles of electrical conductivity (EC) and water temperature taken at 2 m intervals during drilling of 109 boreholes, and samples for stable isotope analysis (δ 18O, δ 2H) taken from 47 boreholes to characterize groundwater recharge, flow and discharge. 222Rn measurements and piezometric evidence were used to complement results from the EC and stable isotopes. The converging evidence shows that groundwater in the study area is characterized by a mix of two different groundwater flow systems: i) the deep groundwater systems are connected to the regional groundwater flow originating from the highlands, outside the surface water basin, ii) the shallow groundwater systems get recharge from local rains. The local recharge zones are located in highly urbanized and industrialized zones posing risk to recharge reduction and pollution. Therefore, attention should be given to protect groundwater resources from contamination and increase groundwater resilience to climate change.

Radiotoxicity and health risk assessment of 222Rn in groundwater using statistical and Monte Carlo simulation approaches

Water is an important natural resource to humans, and itsquality has been a big concern from time immemorial. Water is polluted by the increasing activities of man. Pollutants of major concern include naturally occurring radioactive materials (NORM), heavy and potentially toxic metals, which are ubiquitous in the environment. Naturally occurring radionuclides such as 222Rn are the major precursors of lung and other types of cancer in humans. Exposure to radon in drinking water in excess of 300 pCi/L is treated as a radiological risk, while toxic metals in excess of the World Health Organization (WHO) maximum permissible levels in drinking water are considered both environmental and health risks to humans. A total of 34 groundwater samples were collected in the Akoko area of Ondo State, Nigeria for 222Rn activity concentration determination. The water samples were collected using standard techniques. RAD7 solid-state-detector was utilized for the 222Rn measurements. The results show the activity concentration of 222Rn ranging from 76 pCi/L to 3593 pCi/L with a mean value of 705 ± 76 pCi/L. Inhalation and ingestion doses from 222Rn dissolved in groundwater were evaluated for the infants, children, and adult populations in the study area. Radiological risks were evaluated through statistical and Monte Carlos simulation methods. It can be concluded from this study that there exists a likelihood of radiation-induced health risks due to inhalation of 222Rn from the sampled water.

Quantitative description on initial trace for the solvability to heat equation with exponential boundary in unbounded domain

In this paper, we study the solvability of heat equation in R+N with flux ∂∂νu=exp⁡(pu) on ∂R+N for any constant p>0. The initial trace μ(x) is a Radon measure in RN with suppμ⊂R+N‾ or a nonnegative measurable function in R+N. We at first show the necessary conditions on the initial trace for the existence of solutions for every positive p, and then we divide into three cases to give sufficient conditions on the solvability of solutions, where all of the descriptions on the initial trace are determined quantitatively. For some cases, we identify the strongest singularity on the initial trace to guarantee the solvability of this nonlinear parabolic problem.

Effect of the net radiation proxies on maize and soya evapotranspiration estimation using machine learning methods.

Accurate evapotranspiration (ET) estimation is essential for water management in crops, but it is not an easy task. Empirical ET methodologies require precise net radiation (Rn) measurements to obtain accurate results. Nevertheless, Rn measurements are not easy to obtain from meteorological stations. Thus, this study explored the use of machine learning algorithms with two Rn substitutes, to estimate daily ET: the extraterrestrial solar radiation (Ra) and a modelled Rn (RnM). Support Vector Machine (SVM), Kernel Ridge (KR), Decision Tree (DT), Adaptive Boosting (AB), and Multilayer Perceptron (MLP) were applied to model FLUXNET Rn and ET observations. Adaptive Boosting produced the best field Rn measurements (RnO), yielding a Root Mean Square Error of about 16 % of the mean observed Rn. The resulting Rn (AB RnM) was used to model daily crops ET employing the above-mentioned machine learning methods with RnO, AB RnM, and Ra, in conjunction with meteorological variables and the NDVI index. The evaluated methods were suitable to estimate ET, yielding similar errors to those obtained with RnO, when contrasted with ET observations. These results demonstrate that AB and KR are applicable with rutinary meteorological and satellite data to estimate ET.

The 222Rn and CO2 soil gas distribution at Lembang Fault Zone, West Java - Indonesia

Series of 222 Rn measurements had been employed around the Lembang Fault Zone, West Java – Indonesia to investigate its relationship with the fault zone. Furthermore, the mechanism of 222Rn transport is also investigated by performing soil gas CO2 and its δ13C measurements. The evaluation of 222Rn concentration shows that 34% data are within threshold values with an average of 14,117 Bq/m3, with anomalous concentration greater than 20,000 Bq/m3. The concentration of CO2 in soil gas is varied from 72 ppm to 13,241 ppm and consisted of three populations, with 40% of the data above 655 ppm. The spatial distribution pattern shows that most of Lembang Fault Zone segment coincides with high 222Rn concentration indicating high permeability zone. Furthermore, the average 222Rn concentration in western part of the fault is higher than the eastern part and this may be correlated with higher seismic activities. In contrast to 222Rn, CO2 concentration shows less correlation to the fault structure. Based on δ13C values, the source of soil CO2 is dominated by atmospheric CO2, with minor mixing of biogenic origin. Although Lembang Fault Zone is located in the south of an active volcano, there is no indication of magmatic CO2 origin. The lack of correlation between 222Rn and CO2 suggests that there is no indication of 222Rn transport by CO2 as carrier gas.

Radiological risk associated with 222Rn occurrence in groundwater sources of rural communities in the semiarid region of Paraíba, Brazil.

Rural and isolated communities traditionally lack adequate water treatment and distribution systems, and water quality assessment often does not include radioactivity measurement. Here we present, for the first time, the results of Rn measurements and the evaluation of the associated dose in groundwaters of rural communities in a semiarid area in Paraiba State, Brazil. Water samples were analysed using a low-level liquid scintillation spectrometer (LSS). Radon concentrations were higher than EPA and WHO recommended levels in water for most of the wells (range of 5.5-1107.0Bq/L, average 252.8Bq/L). Higher Rn concentration was measured in deeper wells and located in area rich in granite and diorite rocks. The annual effective doses varied between 0.021 and 4.317mSv/y for infants, 0.016-3.182mSv/y for children, and 0.015-3.022mSv/y for adults, exceeding, in some cases, the 1mSv/y reference level recommended by the WHO and UNSCEAR for the public. Thus, water consumption from half of the wells should be avoided unless adequate treatment is provided. Results highlight the need to perform actions to supply water with appropriate quality to the local population.

Nature of radioactivity of quarry drainage waters in the Novosibirsk region

This study is relevant for obtaining the first geochemical data (including information on radionuclides) on the drainage waters of developed and flooded quarries in the eastern areas of the Novosibirsk Region. The objective of the study was to identify the features of the chemical composition of drainage waters (a wide range of chemical elements from Li to U). The study was carried out by titrimetry, ion chromatography and mass spectrometry with inductively coupled plasma in a laboratory setting at the Hydrogeochemical Problem Research Laboratory (PNIL GGH) of the Engineering School of Natural Resources of Tomsk Polytechnic University (IShPR TPU). Measurements of 222Rn in waters were carried out at the Alfarad Plus facility of the Laboratory of Siberian Sedimentary Basins Hydrogeology of the A. A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences (INGG SB RAS). The data were divided into homogeneous geochemical populations using the coefficients Ca / Na, Ca/ Mg, Ca / Si, Mg/ Si, Na / Si. The chemical composition of the studied objects was found to be highly diverse. The dominant waters have the chemical formula SO4-HCO3 / Na-Mg-Ca with a TDS (total dissolved solids) of 400 to 700 mg/dm3. Three geochemical groups of waters were identified. The first is represented by drainage waters of the developed rubble stone quarries, the second includes facilities of the Gorlovka coal basin, and the third refers to abandoned flooded quarries. The first group is characterized by oxidizing conditions with Eh varying over a wide range from +84.6 to +261.0 mV, pH from 6.9 to 8.6, and O2dissoived from 3.43 to 14.39 mg/dm3. The radionuclide concentrations are (mg/dm3): 238U 9.30 • 10-3 - 1,40; 232Th 1,00 • 10-6 - 2,16 • 10-3; 222Rn activity varies from 1 to 572.5 Bq/dm3. The 232Th / 238U ratio ranges from 4.20 • 10-5 to 2.69 • 10-3 with an average of 8.40 • 10-4. The second group has a smaller Eh variation range of +133.2 to +199.6 mV, pH from 7.5 to 8.5, and O2dissolved from 6.81 to 10.43 mg/dm3. The radionuclide concentrations vary in the following ranges (mg/dm3): 238U 2.26 • 10-3 - 2.90 • 10-2; 232Th 7.5 • 10-6 - 5.57 • 10-4. The 232Th / 238U ratio ranges from 8.37 • 10-4 to 4.80 • 10-2 at an average of 9.54 • 10-3. The third group is also characterized by an oxidizingizing geochemical environment with Eh +131.3 - +250.0 mV, pH from 6.9 to 8.8 and O2dissolved from 4.00 to 16.59 mg/dm3. The radionuclide concentrations are (mg/dm3): 238U 3.00 • 10-4 - 2.74 • 10-2; 232Th 1.65 • 10-6 - 1.15 • 10-5; 222Rn activity varies from 2 to 31 Bq/dm3. The 232Th/ 238U ratio ranges from 2.36 • 10-4 to 1.02 • 10-3 at an average of 6.25 • 10-4. Overall, the 232Th / 238U ratio of the studied waters indicates their uranium nature of radioactivity. The data obtained indicate a slight impact of the drainage water discharge from the abandoned quarries on the environment.