High 222Rn concentrations and dynamics in Shawan Cave, southwest China. (April 2019)

• Record Type: Journal Article
• Authors: Wang, Yanwei; Luo, Weijun; Zeng, Guangneng; Wang, Yang; Yang, Hanling; Wang, Meifang; Zhang, Lin; Cai, Xianli; Chen, Jia; Cheng, Anyun; Wang, Shijie
• Is Part Of: Journal of environmental radioactivity. Volume 199/200(2019)
• Page Start: 16
• Page End: 24
• Publication Date: 2019-04
• Subjects: 222Rn -- Cave ventilation -- Dose exposure -- Chimney effect -- Karst; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2018.12.029
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: Cave 222 Rn 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 222 Rn 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 222 Rn concentrations and large fluctuations in 222 Rn 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 222 Rn. Furthermore, we comparing results from this study with other studies in 35 caves worldwide, and conclude that there are three patterns of seasonal 222 Rn 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. Highlights: Monitored cave 222 Rn concentrations as high as 123000 Bqm −3 . Dose exposure and advices were given according to ICRP recommendations. Seasonal variations of 222 Rn concentration of 35 caves were summarized.