ABSTRACT

Tritium, deuterium and chloride concentrations in the Arima hot spring waters were measured as a clue to their origin and subsurface behavior. T-D-Cl^- relationships clearly indicate that the saline brine of deep origin (T = 0 TR, δD = -30‰ and Cl^- = 43 g/l) is mixed with young meteoric water having T = 30 TR, δD = -50 ‰ and Cl^- = 0g/l in varying proportions to form a group of high chloride hot spring waters. The young meteoric water in a shallow aquifer is also mixed with the older meteoric water in a deeper aquifer characterized by high tritium concentration (∼100TR), forming another group of low chloride waters. The mixing ratio of the two meteoric waters varies with season.