RADON MIGRATION IN SOIL AND ITS RELATION TO TERRESTRIAL GAMMA RADIATION IN DIFFERENT LOCATIONS OF THE GREEK EARLY WARNING SYSTEM NETWORK.

Radon concentration as function of the soil depth was measured during the years (2011-2015), in a location of the Aristotle University campus. Radium distribution in soil was found constant. On the contrary, as expected, radon concentration increases with soil depth. The experimental distribution was reproduced by solving the general transport equation (diffusion and advection). From the general radon migration (diffusion and advection) equation it was indirectly deduced, from the measured radon profile in the soil, the radon exhalation rate from the soil (26.7 ± 4.5 Bq m-2 h-1). In the same location, during 2010-2015, 113 direct radon exhalation measurements were performed and give an average value for the 6 years of 21.1 ± 3 Bq m-2 h-1. The comparison between the radon exhalation rates deduced by the indirect and direct method indicates the validity of the diffusion advection model predictions concerning the radon exhalation rate from soil. The relation between radon migration in soil and terrestrial gamma radiation was studied. In particular, in the present study was investigated the correlation between gamma radiation 1 m above soil and radon exhalation in six locations of the Greek early warning system network. A positive correlation between gamma dose rate in air and radon exhalation rate from soil was found.