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Wang Y, Luo W, Zeng G, Wang Y, Yang H, Wang M, Zhang L, Cai X, Chen J, Cheng A, Wang S. High 222Rn concentrations and dynamics in Shawan Cave, southwest China. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 199-200:16-24. [PMID: 30641397 DOI: 10.1016/j.jenvrad.2018.12.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 09/23/2018] [Accepted: 12/27/2018] [Indexed: 05/22/2023]
Abstract
Cave 222Rn has been a major health issue and subject of scientific debate for decades. While the basics of natural ventilation physics are well understood, it is difficult to make blind predictions of 222Rn concentrations in a given cave due to the complexity of cave systems. In-situ continuous observation is necessary to improve our ability to quantify radiation dose exposure and reduce radiation hazard to cave users, and trace the air exchange patterns occurring in caves. In this study, continuous monitoring using a RAD7 radon detector revealed high 222Rn concentrations and large fluctuations in 222Rn concentration in a small karst cave in southwest China, Shawan Cave. From August 2016 to July 2017, the average annual concentration was 47,419 Bqm-3 and ranged between 3720 and 123,000 Bqm-3, with lower values during summer than other seasons. Taking Shawan Cave as a case study, we suggest a framework to evaluate the potential dose exposure, allowing cave users to minimize risk of exposure to hazardous levels of 222Rn. Furthermore, we comparing results from this study with other studies in 35 caves worldwide, and conclude that there are three patterns of seasonal 222Rn variation. They were classified into five types of ventilation mode based on diversity of cave locations, geometry and connectivity of bed rock fracture networks, together with temperature differences between outside atmosphere and cave air.
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Affiliation(s)
- Yanwei Wang
- University of Chinese Academy of Sciences, Beijing, 100049, China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang, 550081, China
| | - Weijun Luo
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang, 550081, China; Puding Karst Ecosystem Research Station, CAS, Puding, 562100, China.
| | - Guangneng Zeng
- School of Chemistry and Eco-Environmental Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Yang Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang, 550081, China
| | - Hanling Yang
- University of Chinese Academy of Sciences, Beijing, 100049, China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang, 550081, China
| | - Meifang Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang, 550081, China; School of Geography and Environmental Sciences, Guizhou Normal University, Guiyang, 550025, China
| | - Lin Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang, 550081, China; Puding Karst Ecosystem Research Station, CAS, Puding, 562100, China
| | - Xianli Cai
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang, 550081, China; Puding Karst Ecosystem Research Station, CAS, Puding, 562100, China
| | - Jia Chen
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang, 550081, China; Puding Karst Ecosystem Research Station, CAS, Puding, 562100, China
| | - Anyun Cheng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang, 550081, China; Puding Karst Ecosystem Research Station, CAS, Puding, 562100, China
| | - Shijie Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang, 550081, China; Puding Karst Ecosystem Research Station, CAS, Puding, 562100, China
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Akbulut Özen S, Çevik U, Taşkın H. Comparison of active and passive radon survey in cave atmosphere, and estimation of the radon exposed dose equivalents and gamma absorbed dose rates. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2019; 55:92-109. [PMID: 30582824 DOI: 10.1080/10256016.2018.1557163] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 10/31/2018] [Indexed: 05/26/2023]
Abstract
Radon (222Rn) measurements were conducted in the Pileki Cave with Radim 3A Active Radon Monitor equipment. Measurements were also done with the passive sampling method with CR-39 nuclear track detectors by exposing them for three months in the cave. Radon concentrations obtained from the active and passive sampling methods showed that, firstly, the concentrations inside the cave measured by the latter method differed greatly due to high humidity levels up to 88%. The total inside radon exposure dose equivalent people were subjected to was estimated to be 19 µSv a-1 for visitors and 24,065 µSv a-1 for guides. The gamma absorbed dose rates were determined for inside and outside the cave. The dose rates were calculated by means of using the 226Ra, 232Th and 40K activity concentrations and by means of real-time measurements. The gamma absorbed dose rates were found to be much higher than the value of 55 nGy h-1 given by UNSCEAR. In addition, the mineralogical compositions and elemental analyses of samples taken from the cave were determined by XRD and WD-XRF methods.
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Affiliation(s)
| | - Uğur Çevik
- b Department of Physics , Karadeniz Technical University , Trabzon , Turkey
| | - Halim Taşkın
- c Cekmece Nuclear Research and Training Center , Istanbul , Turkey
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Szabó Z, Jordan G, Szabó C, Horváth Á, Holm Ó, Kocsy G, Csige I, Szabó P, Homoki Z. Radon and thoron levels, their spatial and seasonal variations in adobe dwellings - a case study at the great Hungarian plain. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2014; 50:211-225. [PMID: 24437932 DOI: 10.1080/10256016.2014.862533] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 09/04/2013] [Indexed: 06/03/2023]
Abstract
Radon and thoron isotopes are responsible for approximately half of the average annual effective dose to humans. Although the half-life of thoron is short, it can potentially enter indoor air from adobe walls. Adobe was a traditional construction material in the Great Hungarian Plain. Its major raw materials are the alluvial sediments of the area. Here, seasonal radon and thoron activity concentrations were measured in 53 adobe dwellings in 7 settlements by pairs of etched track detectors. The results show that the annual average radon and thoron activity concentrations are elevated in these dwellings and that the proportions with values higher than 300 Bq m(-3) are 14-17 and 29-32% for radon and thoron, respectively. The calculated radon inhalation dose is significantly higher than the world average value, exceeding 10 mSv y(-1) in 7% of the dwellings of this study. Thoron also can be a significant contributor to the inhalation dose with about 30% in the total inhalation dose. The changes of weather conditions seem to be more relevant in the variation of measurement results than the differences in the local sedimentary geology. Still, the highest values were detected on clay. Through the year, radon follows the average temperature changes and is affected by the ventilation, whereas thoron rather seems to follow the amount of precipitation.
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Affiliation(s)
- Zsuzsanna Szabó
- a Lithosphere Fluid Research Lab, Department of Petrology and Geochemistry
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Szabó KZ, Jordan G, Horváth Á, Szabó C. Dynamics of soil gas radon concentration in a highly permeable soil based on a long-term high temporal resolution observation series. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2013; 124:74-83. [PMID: 23669415 DOI: 10.1016/j.jenvrad.2013.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 04/11/2013] [Accepted: 04/12/2013] [Indexed: 06/02/2023]
Abstract
This paper studies the temporal variation of soil gas radon activity concentration in a highly permeable (k = 2.0E-11 m(2)) sandy-gravelly soil in order to understand if temporal variation of soil gas radon activity concentration can affect geogenic radon potential determination. Geogenic radon potential provides information about the potential risk from radon. Its calculation takes into account the equilibrium, saturated at infinite depth, soil gas radon activity concentration (c∞). This concentration may vary at annual time scale due to the environmental conditions. A long-term (yearly) and high temporal resolution (15 min) observation, applied in this study, reveal various temporal features such as long-term trend, seasonality, daily periodicity and sudden events in soil gas radon time series. Results show seasonal and daily periodical variation of the measured soil gas radon activity concentration (csoilRn) in a highly permeable sandy-gravelly soil with definite seasons without obvious long transitional periods. The winter (from October 2010 to April 2011) is characterized by 2.5 times higher average soil gas radon activity concentration (median is 7.0 kBq m(-3)) than the summer (August, September 2010 and May, June, July 2011) (median is 2.8 kBq m(-3)). Daily periodicity, which is much less than the seasonal one, controls the soil gas radon activity concentration mainly in the summer season. Average (AM) value of csoilRn is higher at night than in the daytime with about 18% and 3.8% in summer and in winter, respectively. As a conclusion, in case of single csoilRn measurement on a highly permeable (k ≥ 2.0E-11 m(2)) soil, similar to our test site, csoilRn should be corrected according to the seasons for calculating the equilibrium activity concentration c∞ value.
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Affiliation(s)
- Katalin Zsuzsanna Szabó
- Lithosphere Fluid Research Laboratory, Department of Petrology and Geochemistry, Eötvös University, Pázmány Péter sétány 1/C, 1117 Budapest, Hungary.
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