Measurement of the radon and thoron exhalation rates from the water surface of Yixin lake

The importance of determining the radon exhalation rate from water surface is emphasized by the increased use of radon and its daughter products as tracers in large-scale circulation studies of the atmosphere. There were many methods to measure radon exhalation from water surface. With the development of radon exhalation rate measurement methods and instruments on the surface of the soil, the rock and building materials, so the radon exhalation rate from water surface can be more accurately measured by applying these improved methods and instruments. In this paper, a cuboid accumulation chamber surrounded by foam boards and a RAD7 were used to measure the radon exhalation rate on the water surface at three different positions by Yixin lake. Each measurement was performed 2 h. The radon exhalation rate from the water surface was about 6 x 10(-3) Bq m(-2) s(-1). The thoron exhalation rate from the water surface also can be estimated, it is about 0.16 Bq m(-2) s(-1). These results hint that the radon transmission from the lake bottom soil to water and then into the atmosphere.