222Rn Concentrations In Water Research Articles

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.

Application of a mathematical model to an artificial aquifer under different recharge/discharge conditions using 222Rn as a tracer

Radon (222Rn), a radioactive gas of natural origin, was listed by the World Health Organization in 2009 as the second largest cause of lung cancer (3–14%) after tobacco. Global awareness of the importance of controlling its concentration in water led to the implementation of the European Directive 2013/51/Euratom, which establishes permitted levels in drinking water. This study applies a mathematical model to determine 222Rn concentration in water supplying an artificial aquifer over the full range of recharge/discharge conditions (volumes and times, and therefore flows). This was done by creating an artificial aquifer on a laboratory scale, which reproduces the recharges and discharges experienced by real aquifers through rainwater or groundwater. The equipment used in this study was an RTM 2100 with a specific system for continuous monitoring of 222Rn in water, a high-purity Ge detector for gamma spectrometry, and a portable liquid scintillation counter (LSC) called Triathler for specific measurements of 222Rn in water. The aim of this paper is to show the application of the mathematical model under different recharge/discharge conditions applied to the artificial aquifer. The concentration of 222Rn in water determined by the model can also be used as a tracer to find the origin and volume of water that reaches a real aquifer.

National comparison of methods for determination of radon in water

Abstract The article describes three interlaboratory experiments concerning 222Rn determination in water samples. The first two experiments were carried out with the use of artificial radon waters prepared by the Laboratory of Radiometric Expertise (LER), Institute of Nuclear Physics, Polish Academy of Sciences in Kraków in 2014 and 2018. The third experiment was performed using natural environment waters collected in the vicinity of the former uranium mine in Kowary in 2016. Most of the institutions performing radon in water measurements in Poland were gathered in the Polish Radon Centre Network, and they participated in the experiments. The goal of these exercises was to evaluate different measurement techniques used routinely in Polish laboratories and the laboratories’ proficiency of radon in water measurements. In the experiment performed in 2018, the reference values of 222Rn concentration in water were calculated based on the method developed at LER. The participants’ results appeared to be worse for low radon concentration than for high radon concentrations. The conclusions drawn on that base indicated the weaknesses of the used methods and probably the sampling. The interlaboratory experiments, in term, can help to improve the participants’ skills and reliability of their results.

Hydrogeology and hydrogeochemistry of the Zaeltsovsko-Mochishchensky zone of radon waters in the southern West Siberia

The study aims at solving the fundamental and applied problems of hydrogeology and hydrogeochemistry of the Zaeltsovsko-Mochishchensky zone of radon waters in the northwestern district of the city of Novosibirsk. Novosibirsk is one of the few Russian cities built on granites that emit radon (222Rn). In geological terms, the study area is confined to the NW near-contact zone of the large Novosibirsk granitoid massif. The available data on radon in this area has not been scientifically consolidated yet. We used the methods of S.L. Shvartsev, N.M. Kruglikov, V.V. Nelyubin, O.N. Yakovlev, and V.M. Matusevich and software packages Visual Minteq, PhreeqC, WATEQ4f and HG-32 and obtained physical and chemical calculations for the forms of migration of trace elements in radon waters and estimated the degrees of radon water saturation with rock-forming minerals. The data from hydrogeological profiles and hydrogeochemical sampling (118 samples from 57 water wells and sources) were analyzed. Radon waters are fissure-type, cold (6–10 °С) and occur at a depth of 50–200 m. By their chemical composition (according to the classification proposed by S.А. Shchukarev), the waters are mainly hydro-carbonate calcium and hydro-carbonate calcium-sodium; the total mineralization amounts to 322–895 mg/dm3. All the water wells drilled in granites and near-contact hornfels were tested for radon. It is revealed that the 222Rn concentration in water varies widely, from 11 to 801 Bq/dm3. Therefore, such waters are classified as low-radon and moderate-radon mineral waters (according to the classification proposed by N.I. Tolstikhin). In the wells drilled in hornfels, the 222Rn concentration in water is 37–241 Bq/dm3. The concentrations of 238U and 226Ra do not exceed 0.098 and 1.9∙10–9 mg/dm3, respectively. Physicochemical simulation shows that Ag+, Ba2+, Zn2+, Ni2+, Mn2+, Sr2+, Fe2+ migrate mainly as free ions, while Be2+, Fe3+, Zr4+, Ti4+ migrate as hydroxide complexes. Uranium is mainly present in uranyl-carbonate complexes of calcium: Ca2UO2(CO3)3(aq) (61–75 %) and CaUO2(CO3)32– (25–36 %). Calculations show abundant saturation of the waters with calcite, dolomite, ferrihydrite, greenalite, hausmannite, manganite, quartz, rutile, siderite, lepidocrocite, goethite, and pyrolusite. The mineral phases, such as aragonite, barite, chalcedony, cristobalite, vaterite, and amorphous silicon dioxide are in equilibrium. Several samples show saturation of the waters with relatively rare phosphorus-containing minerals: hydroxyapatite, manganese hydrogen phosphate, cerargyrite, and lead molybdate. The radon waters are not saturated with monohydrocalcite, calcium molybdate, celestite, chrysotile, copper hydroxide, copper molybdate, epsomite, huntite, amorphous and crystalline iron hydroxide (II), gypsum, iron molybdate (II), magnesite, lansfordite, Na-jarosite, nesquehonite, powellite, strontianite, tenorite, witherite, and zirconium dioxide.

Application of the nuclear analytical chemistry (NAC) methods in seismological researches of mud volcanoes and springs in the Black Sea zone

For research of an opportunity forecasting of earthquakes and eruptions of mud volcanoes, monitoring of 222Rn, (and) 226Ra in the springs and gryphones of the mud volcanoes and 222Rn, 220Rn in the soil in the Taman Peninsula occasionally were carried out since 1995. Simultaneous measurements in two springs of the Western Caucasus and in the thermal spring of Southwest Turkey 222Rn were started also. Simultaneous changes of 222Rn concentration in water in Southwest Turkey and South Russia before regional earthquakes were obtained. Reduction of soil 222Rn concentration in territory of mud volcanoes before occurrence of new gryphon was observed.

222Rn and 220Rn levels of Mansa and Muktsar district of Punjab, India

In this study 222Rn (Radon) measurement were performed in water and soil gas and also both 222Rn and 220Rn concentrations were determined in air of Mansa and Muktsar district of Punjab, India. The data then used for calculation of the annual effective dose for health risk assessment of public. Totally 35 locations have been selected for the measurements. All measurements (222Rn and 220Rn) were done with RAD7 detection system. The 222Rn concentration in the water of studied area varies from 0.4 ± 0.2 Bq l-1 to 17 ± 2.8 Bq l-1. The average value of 222Rn concentration in soil, 222Rn and 220Rn concentrations in indoor air are 8 ± 3 kBq m-3, 47 ± 21 Bq m-3 and 39 ± 19 Bq m-3, respectively. The total average annual effective dose for water samples is 13 μSv a- 1 and for indoor air samples is 2.3 mSv a-1. It has been observed that 222Rn concentration in water has increased with depth of groundwater.

Determination of radon activity concentration in drinking water and evaluation of the annual effective dose in Hassan district, Karnataka state, India

The radon concentration has been determined in 27 drinking water samples of Hassan district and was estimated by using emanometry technique and physicochemical parameters were estimated using standard techniques. The 222Rn concentrations in water are varying from 0.85 ± 0.2 to 60.74 ± 2.5 Bq l−1 with an average value of 26.5 ± 1.65 Bq l−1. This study reveals that 66 % of the drinking water samples have radon concentration level in excess of the EPA recommended maximum contamination level of 11.1 Bq l−1. There is no significant correlation noted between radon concentration and physicochemical parameters. The mean annual effective ingestion doses received from all samples are lower than 0.1 mSv y−1.

Identification of latent faults using a radon test

This paper discusses the use of 222Rn concentrations in water of natural springs as a geomorphological method to identify latent faults in low-mid term activity areas. The identification of this type of active fault may be crucial in hazard analysis, structural geomorphology and in landscape evolution analysis. The test used to identify these faults is based on the measuring of 222Rn concentrations in water of springs linked to faults, and comparison with those obtained from springs which, although exactly the same lithological context, are not linked with faults (reference values). If the difference between the measured value and the reference value is positive then an anomaly is identified and that measurement indicates a spring linked to a latent fault. The test was applied and validated in springs linked to faults with a latent behaviour in Cantabria, Northern Spain. These faults have shown an intermittent movement over the last 50,000 years, and have contributed towards landslide processes playing a significant role in landscape evolution of the area.

SPATIAL VARIATION OF WATERBORNE RADON AND TEMPORAL VARIATION OF RADON IN WATER AT NINE MAINE SCHOOLS

Nine elementary schools in Maine were examined to track the release of 222Rn and to determine the transfer coefficient from water into air. Water-use simulations were performed by running sinks and sprayers for 1 h in a kitchen. The 222Rn in air was measured over 24 h throughout the school. The subsequent release of 222Rn into the kitchen air was measured to be greater than the EPA action level of 0.15 Bq L-1 (4 pCi L-1), but negligible concentrations of 222Rn were found in adjacent classrooms. In two schools, more than 10 222Rn-in-air detectors were placed throughout the kitchen and showed a three-fold spatial concentration variation. During the hour-long simulations, the 222Rn in water concentration was measured periodically, and many of the schools showed an increase in the 222Rn concentration in water before remaining constant. These measured variations suggest that multiple detectors are needed to accurately measure waterborne 222Rn in air, and multiple delayed measurements of 222Rn dissolved in water are needed to obtain a representative groundwater sample.

Estimates of the dose due to 222Rn concentrations in water.

About 300 samples of groundwater were collected in the region of Extremadura (Spain) in order to analyse their radon activity concentrations. Correlations with the geological characteristics of the aquifer soil were studied. Internal doses by inhalation due to radon exhalation from the water sample and doses by ingestion were estimated. A model was used to calculate the lung dose due to inhalation of radon exhaled from the water. The estimated lung dose range found for the samples was from 2.1 x 10(-3) to 13 mSv a(-1) (the average contribution to the dose due to radon inhalation in Spain being approximately 1.2 mSv a(-1)). The estimated dose by ingestion ranged from 4.1 x 10(-4) to 3.3 mSv a(-1).

Laboratory scale studies on mitigation of high 222Rn concentrations in air and water

In view of the occasional occurrence of high 222Rn concentrations in air and water under certain circumstances, and in view of the potential health hazards of increased levels of 222Rn in respirable air and in potable water, mitigation of such high 222Rn concentration has become of primary concern. To facilitate the study of the efficiency of the various 222Rn mitigating factors simple laboratory systems were used. Altered alkali granite was used as radon source to enrich air and a piece of pitchblende was used as radon source to enrich water samples. Both enriched media will then be subjected to the mitigation treatments. Charcoal canister technique along with gamma spectrometry were used to measure 222Rn concentrations in air before and after the different mitigating treatments. These were: use of ventilation, radon barriers such as geo-membranes and aluminum sheet, and sealant such as epoxy and vinyl tape. Regarding high levels of 222Rn in air ventilation was the most efficient mitigating factor. Standard liquid scintillation counting was used to measure 222Rn concentrations in water before and after the different mitigation treatments. These were: use of aeration, activated charcoal and heating. Regarding high levels of 222Rn in water, aeration using bubblers and large volume of air was most effective in removing radon from water in a short time. However all the mitigating factors proved effective, in different degrees in decreasing 222Rn concentrations in the respective media. The result from these studies are in general agreement with reports in the literature. It can be concluded then that the different 222Rn mitigating factors can be tested and compared effectively under controlled conditions using simple laboratory scale systems.

Preliminary Report on Radon Concentration in Drinking Water and Indoor Air in Kenya

A screening survey has been carried out to determine activity concentrations of radon (222Rn) in drinking water and indoor air in various locations in Kenya. The concentration of 222Rn in water was measured using a liquid scintillation counter (LSC). Three different passive integrating devices were used in the measurements of 222Rn in air. In the short-term measurements, radon is absorbed in activated charcoal and the analyses were carried out using either LSC or gamma ray spectrometry. The long-term measurements were carried out using solid-state nuclear track detectors (SSNTD). The mean and maximum values of 222Rn concentrations in water are 37 and 410 Bq L−1 and 100 and 1160 Bq m−3, respectively, in air. The highest values were obtained from groundwater sources and in the basements of buildings. When these values are compared with the internationally recommended reference levels, there are indications of existence of radon problems in some of the water sources and the dwellings tested in this survey.

Acute exposure from 222Rn and aerosols in drinking water

Radon-222 in water is released when the water is aerated. As a result, a temporary burst of 222Rn can appear, resulting in an acute exposure. This study looked at homes with 222Rn concentrations in water ranging from 29 600 Bq m −3 to 2 M Bq m −3 to determine the buildup of radon gas in a bathroom during showering. Samples from the tap and drain showed that between 58% and 88% of 222Rn in the water was released. The actual increase in 222Rn in the air was measured and ranged from 74 Bq m −3 to 4200 Bq m −3 in closed bathrooms (10 to 15 min showers, water flow rates from 3 L/min to 6 L/min). Significantly, these radon concentrations stayed approximately the same for up to 20 min after the water flow ceased. Additionally, filter samples of bathroom air were measured and showed an increase in 222Rn progeny, notably polonium-218 ( 218Po) and -214 ( 214Po), in the air after showering. These increases were gradual and were on the order of 18.5 Bq m −3 at the highest level after 10 min. Lastly, the percentage of radiation available in aerosols smaller than 7 μm was measured and showed that up to 85% of the radiation available in the aerosols is contained in these smaller, more respirable particles.

Determination of waterborne 222Rn concentrations using AC canisters.

A method for measuring 222Rn concentration in water using charcoal canisters is presented. 222Rn is transferred within a few minutes from water contained in a 0.720 L bottle to a charcoal canister using a portable degassing unit. In the laboratory, gamma counting is performed at least 10 h after sampling to determine waterborne 222Rn concentration. The results obtained with charcoal canisters are compared to measurements made with Marinelli beakers calibrated in a comparison with liquid scintillation counting. The efficiency of transferring dissolved 222Rn in water to activated charcoal is 99%, based on measurements made using Marinelli beakers. The lower limit of detection at the 95% confidence level is approximately 1 kBq m-3 for a 15 min gamma count. The system was used to measure radon concentration in mineral groundwater near Rome.

Relationships between 222Rn dissolved in ground water supplies and indoor 222Rn concentrations in some Colorado front range houses.

Indoor 222Rn concentrations were measured in 37 houses with alpha track detectors placed in water-use rooms near water sources (bathrooms, laundry rooms, and kitchens) and in non-water-use living rooms, dining rooms, and bedrooms away from water sources. Results show that relative contributions of 222Rn to indoor air from water use are insignificant when soil-gas concentrations are high but become increasingly important as the ratio of 222Rn-in-water: 222Rn-in-soil gas increases. High soil-gas 222Rn concentrations may mask 222Rn contributions from water even when waterborne 222Rn concentrations are as high as 750 kBq m-3. Ground water in Precambrian Pikes Peak granite averages 340 kBq m-3 222Rn, vs. 170 kBq m-3 in Precambrian migmatite, but average 222Rn concentrations in soil gas are also lower in migmatite. Because the ratio of 222Rn-in-water: 222Rn-in-soil gas may be consistently higher for houses in migmatite than in Pikes Peak granite, indoor air in houses built on migmatite may have a greater relative contribution from water use even though average 222Rn concentrations in the water are lower. Continuous monitoring of 222Rn concentrations in air on 15-min intervals also indicates that additions to indoor concentrations from water use are significant and measurable only when soil-gas concentrations are low and concentrations in water are high. When soil-gas concentrations were mitigated to less than 150 Bq m-3 in one house, water contributes 20-40% of the annual indoor 222Rn concentration in the laundry room (222Rn concentration in water of 670 kBq m-3). Conversely, when the mitigation system is inactive, diurnal fluctuations and other variations in the soil-gas 222Rn contribution swamp the variability due to water use in the house. Measurable variations in indoor concentrations from water use were not detected in one house despite a low soil-gas contribution of approximately 150 Bq m-3 because waterborne 222Rn concentrations also are low (80 kBq m-3). This result suggests that 222Rn concentrations in water near the recommended EPA limit in drinking water of 11 kBq m-3 may not contribute measurable amounts of 222Rn to indoor air in most houses.

Contribution of 222Rn in Domestic Water Supplies to 222Rn in Indoor Air in Colorado Homes

The contribution of 222Rn from domestic water wells to indoor air was investigated in a study of 28 houses near Conifer, CO. Air concentrations determined by alpha-track detectors (ATDs) and continuous radon monitors were compared with the predictions of a single-cell model. In many of the houses, the water supply was shown to contribute significantly to levels of indoor 222Rn. The data from the ATD study were augmented with a continuous monitoring study of a house near Lyons, CO. The well water in that house has the highest known concentration of 222Rn in water yet reported (93 MBq m-3). The temporal pattern in the indoor 222Rn concentration corresponds to water-use records. In general, it is difficult to quantify the proportion of indoor radon attributable to water use. Several lines of evidence suggest that the single-cell model underestimates this proportion. Continuous-monitoring data, although useful, are impractical due to the cost of the equipment. We propose a protocol for 222Rn measurement based on three simultaneous integrating radon detectors that may help estimate the proportion of indoor 222Rn derived from the water supply.

Location of groundwater seepage points into a river by measurement of 222Rn concentration in water using activated charcoal passive collectors

A new method to measure 222Rn concentration in water is described. This method is an application of the activated charcoal passive collector method, which is sometimes used for measurement of 222Rn concentration in air. The model and the equation which express the quantity of 222Rn adsorbed in activated charcoal in the collector were constructed, inspected experimentally, and proved to work well enough for the measurement of relative concentration of 222Rn in water. We used this method to measure the 222Rn concentration in water at ∼ 20 points in an actual river. Based on the fact that the concentration of 222Rn in ground water is generally much higher than that of surface water, we found several possible groundwater seepage points along the river. For the absolute measurement of 222Rn concentration in water by this method, it would also be necessary to investigate the effect of temperature on the quantity of 222Rn collected in a collector.

Rapid measurements of 222Rn concentrations in water with a commercial liquid scintillation counter.

Abstract A technique is described by which concentrations of 222Rn in water as low as 10 pCi/l can be determined by a 40-min count of a 10-ml sample. Preparation time is about 1 min/sample, and no special equipment is required other than access to a commercial liquid scintillation system.