一般環境におけるトリチウムの挙動とモニタリングのための予備知識

抄録

An attempt is made to review behavior of tritium released into the environment in order to give preliminary knowledges for monitoring present and future levels of tritium in the environment. A systematic distribution of bomb-produced tritium on a global scale has been recognized from an evaluation of the precipitation data conducted by the IAEA-WMO Precipitation Network Survey. Latitudinal dependence and continental effect of the tritium concentration in precipitation were found pronouncedly. The mean residence times of several compartments of hydrological cycle for tritiumm are discussed topically. Recent tritium concentration in environmental water in Japan are summarized. Organically bound tritium in sediments, aquatic plants, fish, and foodstaffs sometimes showed higher concentration than tritium in ambient water. This is probably explained as memory effect or inheritance effect through eco-systems due to long residence time of organically bound tritium. Instrumentation, detection limit and dose calculation for tritium monitoring are proposed. Tritium surveillance activities conducted by U. S. Government are reviewed also historically with some representative data.