Studies on radon in soil, its concentration in the atmosphere and gamma exposure rate around Mysore city, India

Concentrations of radon in soil, rate of its exhalation from the ground surface and its concentration in the atmospheric air have been studied in and around Mysore city (12 deg N and 76 deg E). Variation of radon concentration in the soil-gas under dry and wet conditions at different depths was also studied. Radon in soil-gas was found to increase with depth and decrease with increase in moisture content of the soil. Radon in soil varies from 0.11 to 11.85 kBq m-3 with a median of 1.92 kBq m-3. The annual average values of radon and its progeny concentrations in the atmosphere vary from 15.33 to 47.81 Bq m-3 with a median value of 24.36 Bq m-3 and 0.08 to 3.54 mWL with a median value of 0.33 mWL respectively. Good correlations were observed between radon in soil, radon exhalation rate from the ground surface and radon concentration in the atmosphere in these locations. 226Ra in soil at these locations was also estimated using the HPGe detector. The activity of 226Ra varies from 11.3 to 74.2 Bq kg-1. Radon concentration in soil-gas shows good correlation with the activity of 226Ra in soil. The correlation coefficient was 0.76. (author)