Continuous measurement of radon exhalation rate of soil in Beijing.

To understand the level of radon exhalation rate from soil surface and its variation, a continuous measurement system was developed and applied for a field measurement in Beijing from April 2012 to February 2013. For seasonal variation, It was indicated by measurement results that radon exhalation rate was higher in spring (52.9 mBq m s in average) and lower in winter (17.0 mBq m s in average). The precipitation had a strong influence on the radon exhalation rate, usually radon exhalation rate increased quickly after rain. Daily variation of radon exhalation rate was also observed in spring, usually higher at noon and lower at midnight. [ABSTRACT FROM AUTHOR]