222Rn Activity Research Articles

Radon concentration and radiation hazard of a rare earth waste dump in China

The 222Rn activity concentration and air absorbed dose rate of a rare earth waste slag heap in China were measured by radon and air absorbed dose rate instruments. A total of 34 monitoring points including waste residue heaps were selected. The 222Rn activity concentration and absorbed dose rate measurement ranges are 51.0–246.9 Bq/m3 and 0.071–0.110 ​μGy/h. Other radiation hazard indicators: outdoor annual effective dose (Eout), annual effective dose from radon (Eradon)), excess lifetime cancer risk for outdoor (ELCRout), excess lifetime cancer risk for radon (ELCRradon), and excess lifetime cancer risk for total (ELCRtot) were calculated. They were 0.087–0.135 ​mSv/y, 0.409–1.640 mSv/y, 0.305–0.472 ​× ​10−3, 1.577–6.314 ​× ​10−3, and 1.959–6.787 ​× ​10−3. The results show that the radiation hazard indicators at all monitoring sites were within the international level. The annual effective dose at 33 monitoring sites in the human activity areas was lower than 1 mSv/y recommended by ICRP for public exposure. Data obtained in this study can be used to treat waste residue heaps and develop and utilize surrounding areas.

222Rn and 226Ra concentrations in selected shallow circulation groundwaters from the Fore-Sudetic Monocline area

Natural radioactive isotopes occur in various components of the natural environment, including groundwater. The general population, not always aware of possible threats, can use its resources. The activity concentration of some of the radioactive isotopes should be monitored, especially in those intakes from which it is possible to obtain water for human consumption, e.g. in domestic wells. The conducted research was innovative due to the fact that in many countries, including Poland, there are no regulations on waters exploited from home wells using as a drinking water source. As the groundwaters from this area have not been examined for radon (222Rn) and radium (226Ra) occurrence yet, the goal of this research was to perform screening tests in this part of the Fore-Sudetic Monocline. For this purpose, the authors have measured the concentration of 222Rn and 226Ra activity in groundwater collected from this geological unit located in south-western Poland. 222Rn and 226Ra occurrence was researched, and specific electrolytic conductivity, redox potential, pH and temperature were measured in 52 groundwater samples. 222Rn activity concentration ranged from 0.18 to 19.78 Bq/dm3. Only in three cases, 226Ra activity concentration reached a value above the lower detection limit of the applied method, i.e. 0.05 Bq/dm3 (max. 0.77 Bq/dm3). The authors present completely new data on the occurrence of these radioactive isotopes in the waters of the first aquifer in the Fore-Sudetic Monocline, which is not without significance for the health of consumers of these waters.

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.

Using 222Rn temporal and spatial distributions to estimate the groundwater discharge rate and associated nutrient fluxes into high salinity lakes in Badain Jaran Desert, Northwest China.

Groundwater is the main source of water and salt recharge for to lakes in arid regions. Quantifying the groundwater discharge and its nutrient input is important in the evolution of lake environments in the Badain Jaran Desert (BJD), Northwest China. In this study, ten BJD lakes were sampled for 222Rn in April and September 2021, and the 222Rn mass balance model was used to quantify the groundwater discharge rates and derived nutrient fluxes to these lakes. The results showed that the 222Rn activity and the groundwater recharge rate of lake water both present a positively correlated with lake water depth. The hot points of high 222Rn activity in the lake water were consistent with the locations of groundwater discharge areas. According to the 222Rn temporal and spatial distributions, the mean groundwater recharge rates for the ten lakes in April and September were 5.4 ± 0.6 and 7.7 ± 1 mm/d, respectively, and the annual mean groundwater discharge rates varied between 1.1 ± 0.2 and 14.6 ± 1.6 mm/d, with a mean of 7 ± 0.9 mm/d. Given that all the perennial lakes in the BJD have the same groundwater recharge rate as the mean recharge rate of the ten studied lakes, the annual mean groundwater recharge amount received by the lakes in the entire BJD is (5.6 ± 0.7) × 107 m3/a. According to the groundwater recharge amount, the inputs of dissolved inorganic nitrogen, dissolved inorganic phosphorus, dissolved inorganic silicon, total nitrogen, and total phosphorus to the BJD lakes from groundwater were (4.7 ± 0.6) × 105, (3.8 ± 0.5) × 104, (7.9 ± 1) × 105, (7.2 ± 0.9) × 105, (2.5 ± 0.3) × 104 kg/a, respectively. This study provides a reference for quantifying of groundwater discharge rates into salt lakes in other arid regions.

Correlation between Ground 222Rn and 226Ra and Long-Term Risk Assessment at the at the Bauxite Bearing Area of Fongo-Tongo, Western Cameroon

The aim of the current work was to study natural radioactivity in soil and the correlation between 222Rn and 226Ra in the ground and to assess the onsite and indoor long-term excess cancer risk at the bauxite bearing area of Fongo-Tongo in Western Cameroon. 222Rn was measured in the ground at a depth of one meter, using Markus 10 detector. 226Ra, 232Th, and 40K activity concentrations were measured in soil by two techniques, in situ and laboratory gamma spectrometry. The mean values of 222Rn concentrations in the ground were 69 ± 18 kBqm−3 for Fongo-Tongo and 82 ± 34 kBq m−3 for the locality of Dschang, respectively. The mean values of 226Ra, 232Th, and 40K activity concentrations obtained with in situ gamma spectrometry were 129 ± 22, 205 ± 61, and 224 ± 39 Bq kg−1 for 226Ra, 232Th, and 40K, respectively, and those obtained by laboratory gamma spectrometry were 129 ± 23, 184 ± 54, and 237 ± 44 Bq kg−1, respectively. A strong correlation between 222Rn and 226Ra activity concentrations determined by in situ and laboratory measurements (R2 = 0.86 and 0.88, respectively) was found. In addition, it is shown that the total excess cancer risk has a maximum value of 8.6 × 10−3 at T = 0 year and decreases progressively in the long term. It is also shown that 226Ra makes a major contribution, i.e., above 70%, to the total excess cancer risk.

Time variation of radon in tap water in locations of a Greek area with geological background for elevated radon-in-water concentrations and correlation study between radon, gross alpha, uranium, and radium concentrations

Background: Radon (222Rn), a naturally occurring radioactive gas, dissolves in water, and it can be found in elevated concentrations in public water supplies when water originates from ground sources in areas rich in uranium. An area of great interest for measuring radon-in-water is the Migdonia basin in Northern Greece due to its geological background and because all of its villages are supplied with water from boreholes.
 Objectives: The main aim of this paper was to study the time variation of radon in tap water activity concentration in nine villages of the Migdonia basin supplied with water from boreholes and to determine factors that may affect it. Radon in water correlation between the source (borehole) and the consumption point (tap) was studied for some villages. Also, the correlation among radon, gross alpha, beta, uranium (238U), and radium (226Ra) activity concentration in water was studied.
 Design and methods: Water samples were collected and measured for their radon activity concentration from 66 villages in the Migdonia basin in order to find places with relatively high radon concentrations. The time variation of radon-in-water was studied for villages that showed relatively high radon concentrations for 3–4 years (2018–2022). All samples were measured for their 222Rn activity concentration using gamma-ray spectrometry. Water samples were also analyzed for their gross alpha, beta, and uranium isotopes activity concentration.
 Results and conclusions: Average radon in tap water activity concentrations measured in the area ranged from background concentrations to 185 Bq L-1. The corresponding annual effective doses from waterborne radon inhalation using both UNSCEAR and ICRP dose conversion factors ranged from 0.01 to 0.466 mSv y-1 and from 0.02 to 0.868 mSv y-1, respectively, while radon ingestion annual effective doses varied from 0.007 to 0.324 mSv y-1. Time variation of radon activity concentration in tap water for villages supplied from one borehole or a constant number of boreholes showed relatively low standard deviations (<24%) at a coverage factor of k = 1. Those deviations are probably caused by the time variation of boreholes’ radon concentration and water demand changes. A significant decline in radon concentration from the source (borehole) to the consumption point (tap water) was observed. Therefore, sampling should be performed at the consumption point. However, knowing the supplying borehole concentration is useful as it determines the potential for radon in drinking water. No apparent correlation was found among radon, gross alpha, beta, uranium, and radium concentrations in water. However, in some cases, remedial actions (withdrawal of boreholes) for uranium concentration also decreased radon concentration.

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.

Origins and transformations of terrigenous dissolved organic matter in a transgressive coastal system

Hydrogeological, geochemical, and optical approaches were combined to explore how a transgressive coastal system, where 2-kyr-old organic matter is preserved, contributes to dissolved organic matter (DOM) and dissolved organic carbon (DOC) flux to coastal waters. The sand spit system, located on the St. Lawrence shore (Chaleur Bay, Québec, Canada), was mainly composed of saline groundwater from seawater recirculation, and we estimated submarine groundwater discharge (SGD) velocities fluctuating from 0 during the rising tide to 106 cm d−1 during the ebb tide. The radon-222 (222Rn) activities revealed the presence of two distinct water masses in the spit: a surface recirculated saline groundwater cell with a short residence time and low or no 222Rn activity, and a deeper recirculated saline groundwater with a longer residence time, from a few hours to a few days, and thus exhibited higher 222Rn activities. At the falling tide, the upward flow of this 222Rn-rich groundwater contributes to volumetric discharges ranging from ∼6 to ∼17 m3 d−1, corresponding between 10 and 30% of the total SGD. Both DOC and DOM were produced in the subsurface. However, despite the concentrations being high in the discharge zone, the DOC export remained weak, with mean fluxes of 60.7 (±15.5) and 55.8 (±36.5) mol C yr− 1 in 2018 and 2019, respectively. While surface recirculated saline groundwater dominates the SGD, absorbance and fluorescent indices indicated a strong terrestrial character in the DOM pool likely originated from material sources with a high degree of humification. An EEM-PARAFAC model reveals the dominance of humic-like components of high molecular weights and the occurrence of degraded material, whatever the tidal regime. When the residence time of the groundwater was longer, with higher radon activities, protein-like components with lower molecular weights were microbially produced, probably enhancing the bioavailability of the DOM exported to surrounding seawater. Our results suggest that transgressive coastal systems can be a hot spot for terrigenous DOM transformation which could affect the optical and chemical properties of coastal waters.

Ba/Ca in foraminifera shells as a proxy of submarine groundwater discharge

AbstractSubmarine groundwater discharge (SGD) can have a profound influence on marine environments and elemental biogeochemical cycles in coastal waters. We have explored the feasibility of using Ba/Ca ratios of benthic foraminiferal shells as a proxy of SGD. Dissolved barium (DBa) displayed enrichment behavior in bottom waters indicating that SGD is a major DBa source in the Changjiang (Yangtze) Estuary. Foraminifera that lived in bottom waters with elevated 222Rn activities (high SGD) showed a larger range of Ba/Ca ratios than those that lived under low bottom water 222Rn activities (low SGD). Our findings support the view that benthic foraminiferal Ba/Ca ratios could be treated as a qualitative proxy of SGD. We propose that in areas where SGD is the main source of DBa, foraminiferal Ba/Ca ratios could be applied for long‐term historical SGD records.

Seasonal and geological controls of radon (222Rn) in groundwater of Vamanapuram river basin, SW India

The study investigates the spatio-temporal variability of radon (222Rn) with respect to the geology and hydrogeology of the Vamanapuram River Basin (VRB), SW India. A total of 40 groundwater samples were collected during three seasons of 2019. RAD7, RAD-H2O accessory (Durridge Co. USA) was used to analyse 222Rn, and physico-chemical parameters were measured in situ by Horiba Laqua water quality analyser. The results show that the 222Rn activity was in the range of 640–79,940 Bq/m3 in pre-monsoon, 250–36,950 Bq/m3 in monsoon and 420–59,790 Bq/m3 in post-monsoon season and 18% of samples exceeded the permissible limit of USEPA (11,000 Bq/m3) during all seasons. Remarkably, the samples exceeding the permissible limit of 222Rn were associated with khondalitic rocks with notable amount of uranium-bearing minerals and NW-SE trending lineaments, the most active type of lineament in the study area. The study shows the considerable influence of seasons and the highest activities were found during pre-monsoon compared to the other two seasons.

Radon in groundwater sources of Bosso Community in North Central Nigeria and concomitant doses to the public

Realizing the probable health hazards from radon exposure, potable groundwater samples (hand-dug wells and boreholes) in the Bosso community of North Central Nigeria were collected and assayed for radon concentration. Durridge RAD-7 detector together with RAD-H2O accessories was employed in this study. The committed effective dose to different ICRP age groups was computed using various parameters including the annual water consumption characteristics. The mean 222Rn activity in water samples from hand-dug wells and boreholes were 9.81 ± 1.85 Bq/L and 24.78 ± 2.48 Bq/L respectively. The average whole-body committed effective dose due to ingestion and inhalation of waterborne radon from the two groundwater sources are 0.026 mSv/y and 0.067 mSv/y for hand-dug wells and boreholes respectively, which are below the safety threshold of 0.1 mSv/y recommended by the European Union. The results showed that there is no significant radiation threat to public health from inhalation and ingestion of waterborne radon within the community.

Radon concentration in groundwater of north-eastern Sicily (Italy)

This paper presents analyses of 222Rn activity concentration performed on groundwater samples collected from wells and natural springs in 70 different sites of the crystalline area of north-eastern Sicily (southern Italy), up to now poorly studied. Alpha spectroscopy of the short-lived radon progeny was used to measure the 222Rn activity concentration by means of the Durridge RAD7 + H2O setup. Radon concentrations were derived to be in the range of 1.6–57.5 Bq L-1. The higher values were detected along fluvial valleys and in the crystalline reliefs, whereas aquifers hosted in the alluvial plains show lower radon concentrations. The annual effective dose due to intake of radon by ingestion ranges from 4 to 146.8 μSv y-1. The average value (56.5 μSv y-1) is below the recommended limit of 100 μSv y-1 proposed by the World Health Organization (WHO). In addition, all the measured radon values are lower than the reference level of 100 Bq L-1 set by the Italian legislative decree 28/2016 and by the European Directive 2013/51/Euratom. Therefore, all sampling sites are fully compliant with the legislative requirements in terms of radon levels. Moreover, results show that the radon levels measured in groundwater from north-eastern Sicily are similar to those determined for the adjacent area of southern Calabria, promoting the assumption of a uniform radon signature in the crystalline domain of southern Italy. However, further studies are needed to define better the role of tectonic activity on the content of dissolved radon in groundwater.

Study on Estimation of Inhalation and Ingestion Dose due to <sup>222</sup>Rn Concentration in Different Types of Ground Water of Some Taluks of Uttara Kannada District, Karnataka, India

The primary goal of this study was to determine the risk due to radon concentration in drinking water. Water is essential for most of the life on the Earth, and the quality of drinking water is a key criterion for one's health. Radon (222Rn) and radium (226Ra) are the radioactive elements that can be found in water. Thirty samples of drinking water were collected in Haliyal, Joida, and Mundgod taluks of Uttara Kannada district. Emanometry technique was used to determine the concentration of 222Rn activity. The activity concentration of 222Rn in water varies between 3.78 ± 0.38 Bq l-1. and 135.96 ± 1.72 Bq l-1 with a mean value of 26.23 ± 0.65 Bq l-1. The cumulative average annual effective doses for all of the samples under investigation are well below the safe limit of 100 µSv y-1 suggested by WHO.

Effective coastal Escherichia coli monitoring by unmanned aerial vehicles (UAV) thermal infrared images

Coastal Escherichia coli (E. coli) significantly influence ocean safety and public health, thus requiring an effective E. coli pollution monitoring. However conventional detection relying on manual field sampling is time-consuming. Here, this study established an E. coli estimation model based on thermal remote sensing of unmanned aerial vehicles (UAV). This model was developed against one-year comprehensive field work in a representative sandy beach and further validated against 50 beaches in Hong Kong to evaluate its applicability. The estimated E. coli concentrations were in a reliable agreement with direct measurements. For this model, this study deployed the radon-222 (222Rn) as a bridging tracer to couple UAV thermal images and coastal E. coli concentrations. Coastal 222Rn can be reflected on the UAV thermal images, and there was a good positive correlation between the 222Rn activity and coastal E. coli concentration via one-year field data. Hence, coupling the 222Rn activity estimated from UAV thermal images and the relationship between 222Rn and E. coli, this study can readily monitor coastal E. coli by UAV. These findings highlighted that UAV technology is an effective approach to measure the E. coli concentrations and can further pave the way for an efficient coastal E. coli monitoring and public health risk warning.

Unravelling groundwater and surface water sources in the Esteros del Iberá Wetland Area: An isotopic approach

In the Esteros del Iberá Wetland Area (EIWA, NE Argentina), the southern sector of the transboundary Guarani Aquifer System (SAG) is overlain by the Ramsar listed Iberá Wetlands and several rivers, that combined extend across 37,930 km2 and represent one of the largest freshwater systems on the South American continent. Previous hydrogeological studies encompassing the entire SAG proposed preferential discharge of groundwater of various origins and ages to the EIWA. In this study, a multi-tracer study using major ionic species, δ18O, δ2H and 222Rn was conducted in lagoons, rivers, wells, and boreholes in the EIWA to confirm if discharge from the transboundary SAG is contributing to the surface water system. End-member Mixing Analysis (EMMA) determined the existence of four main end-members: groundwater from the SAG, more saline groundwater from the deeper Pre-SAG, and two poorly mineralised end-members from shallow, Post-SAG. EMMA calculations clearly illustrated complex binary and ternary mixing patterns involving the four end-members and highlighted the role of geological structures, specifically regional steep faults, in controlling the mixing patterns. 222Rn activities allowed in-situ identification of preferential deep groundwater discharge into both surface waters and shallow groundwaters. These findings provide strong evidence for the widespread existence of upward flows along major faults in this sector of the SAG, inducing complex mixing flow patterns and explaining the presence of old groundwater in shallow aquifers. Mapping the sources of water and the hydrological interactions are relevant for improving water balance estimates and develop management policies towards the preservation of these wetlands.

ACTIVITY OF 222Rn IN TAP WATER IN KIELCE COUNTY

Radon is known as a radioactive element that dissolves easily in water. It is worth mentioning that it is available in all possible reservoirs. Its concentration cannot be measured directly but only from the emitted radiation. Investigations of 222Rn activity in water in the Kielce district were subjected to three selected water intakes: Bolechowice, Kołomań and Wola Kopcowa. This type of research was conducted for the first time in the discussed area. The results were analyzed in detail in terms of acceptable concentrations. Next, it was determined whether the geological location of the intakes in question may have an impact on the amount of radon present in water from the water supply network.

Hydrogeochemistry and stable isotopes in radon-rich thermal waters of Belokurikha (Altai, Russia).

The first integrated isotope and chemistry results have been obtained for radon-rich thermal waters from the Belokurikha field which are used at a large spa resort in Altai, Russia. The waters reside in an unconfined aquifer composed of Quaternary soft sediments and in a confined (artesian) aquifer of monolithic to weathered Upper Paleozoic granites. The waters belong to three geochemical groups: low-radon nitrogen-silicic interstitial waters in weathered Paleozoic granites; groundwaters of REE-enriched and background compositions; surface waters of the Belokurikha River. The interstitial waters in granites have HCO3-SO4 Na and SO4-HCO3 Na major-ion chemistry, total salinity from 198 to 257 mg/L, pH = 8.6-9.6, silica contents of 19.8 to 24.6 mg/L, and 222Rn activity from 160 to 360 Bq/L (290 Bq/L on average). Judging by their oxygen and hydrogen (deuterium) isotope compositions (-17.5 to -14.2 ‰ and -126.9 to -102.7 ‰, respectively), the Belokurikha aquifers recharge with infiltrating meteoric water, especially the winter precipitation. The carbon isotope composition of dissolved inorganic carbon (-9.7 to -25.6 ‰ δ13СDIC) corresponds to biogenic origin. Comparison of radon-rich mineral waters from different areas of southern Siberia shows that the change from oxidized to reduced environments leads to 232Th/238U increase from 4.20∙10-5-7.39∙10-2 to 0.0022-26, respectively, with an intermediate range of 2.63∙10-5-0.20 in transitional conditions.

Distribution of 222Rn in Seawater Intrusion Area and Its Implications on Tracing Submarine Groundwater Discharge on the Upper Gulf of Thailand

Abstract Radon (222Rn) has been widely employed as a tracer for estimating submarine groundwater discharge (SGD). However, the uncertainty of the SGD estimation remains significant, due to the spatial variability of radon in groundwater. In this study, we analyzed the hydrochemical proprieties of seawater and coastal groundwater in the Upper Gulf of Thailand and discussed the distribution characteristics of 222Rn in aquifers in terms of aquifer lithology, groundwater system recharge conditions, and water retention time. The results suggested that the residence time of groundwater and the process of groundwater salinization have the greatest impact on the distribution of 222Rn activity. A 222Rn mass balance model, synthesizing the distribution characteristics of 222Rn in groundwater and tidal influences on SGD, was built to estimate the submarine groundwater discharge in the Upper Gulf of Thailand. The result showed that the SGD flux of the Upper Gulf of Thailand was 0.0203 m/d. Moreover, there is a positive correlation between tidal height and the activity of 222Rn in groundwater. The SGD observed during the low tide was about 1.25 times higher than that observed during the high tide. This may influence the marine geochemical cycles of elements and their impact on marine ecosystems.

Thoron activity concentration in Malaysian soil gas: Geogenic impact assessment

Given the rather short half-life of thoron (220Rn), at 56 s, its contribution to radiation exposure is often overlooked. Nevertheless, in a thorium (232Th) rich environment potential hazard does exist, in particular regarding prolonged duration exposures to 220Rn and its short-lived alpha-particle emitting progeny [polonium (216Po)]. Herein, concerning the geology and major soil types in the Malaysian state of Perak, an activity concentration map has been established for 220Rn in soil gas, with the use made of a RAD7 detector and the THORON protocol for in-situ measurements. The detector has been coupled to a soil probe driven to a depth of 0.8 m. The activity concentration of 220Rn in the soil ranged from undetectable to 563 kBq m−3 with a mean value of 38 ± 11 kBq m−3. Granite and Triassic-Jurassic formations in the region showed more elevated 220Rn activity while Quaternary and Silurian formations revealed low 220Rn values. Moreover, while elevated 220Rn activity concentrations were found in peat, riverine, and granite source soils, the activity concentrations in marine and other soils were low. A primary map of 220Rn in the soil gas has been developed based on geogenic impact assessment, with a greater 220Rn activity concentration in the central part of the state.

Radiological Hazard Related with Natural Radioactivity in Natural Gas Transportation—A Case Study from Poland

Activity concentration of 210Pb in black powder and gamma radiation dose rate related to natural gas transportation were discussed. As part of the research, the content of radiolead (210Pb) in black powder, spent filter containers, radon (222Rn) activity concentration in natural gas and gamma radiation dose were measured around selected points of natural gas transportation infrastructure in Poland. The content of some heavy metals was also analyzed. The average concentrations of 222Rn and 210Pb ranged from 30 to 1400 Bq/m3 and from around 450 to 16,000 Bq/kg, respectively. The external exposure to gamma radiation was low; the gamma radiation dose rate was at the level of background radiation or slightly exceeded it. The research demonstrated that the content of 210Pb in black powder is strongly related to radon concentration in natural gas, the volumetric flow rate of the transported natural gas and solid fraction content. Some black powder samples should be classified based on 210Pb content as low-radioactive waste.