<sup>3</sup>H/ <sup>3</sup>He-based groundwater ages for springs located at the foot of Mt. Fuji

Information of groundwater age is important for understanding circulation rate and resource of groundwater flow system.In this study, dating method using 3 H/ 3 He was applied to 5 springs located at the foot of Mt.Fuji. 3 H/ 3 He-based groundwater ages were determined successfully for 4 springs, ranging from 18 to 39 years.This 3 H/ 3 He ages is consistent with hydrogeological setting of Mt.Fuji and with reported ages estimated by 36 Cl, CFCs and SF 6 , suggested that 3 H/ 3 He method becomes a powerful tool in dating groundwater around Mt. Fuji area.