Abstract
The 222Rn concentrations in soil and 222Rn flux were measured in the campus of Nagoya University. The measurements were carried out discontinuously between December 1999 and March 2002 at depths of 15, 30, 50, 80, 120, and 200cm. The 222Rn concentrations in soil were analyzed for seasonal-, day-to-day-, and diurnal variations. The average values of 222Rn concentrations in soil were 1.6, 6.9, 13.6, 24.2, 27.7, and 34.3kBq·m-3 for soil depths of 15, 30, 50, 80, 120, and 200cm, respectively. The 222Rn flux ranged from 2.5 to 14mBq·m-2·s-1 with the average 7.2mBq·m-2·s-1. The variations of 222Rn concentrations in soil were larger in shallow depths. It seems that the 222Rn concentration in soil during night-time was slight lower than day-time especially at depth 15cm. The precipitation may have affected the 222Rn concentration in soil differently depending on its amounts. The large decrease of air pressure during one day increased the 222Rn concentration in soil at the depth 15, 30, and 50cm. The effect of soil water content on 222Rn concentration in soil was also observed.
