2005 Volume 54 Issue 12 Pages 593-597
Concentration of 222Rn in well water at Meiji University, Kawasaki, Japan, was observed from 2000 to 2001. The 222Rn concentration in the groundwater ranged from 3 to 5 Bq/L. The variation pattern of monthly averaged concentration of 222Rn in the groundwater was similar to that of precipitation: the monthly averaged concentration in groundwater tended to increase in summer and autumn with large amount of precipitation and to decrease in winter and spring with small amount of precipitation. The variation pattern suggested that the precipitation may give rise to the mixing of groundwaters of different origins.