The behaviour of tritium in the environment

Recent advances and the practical aspects of ³H-utilization and monitoring are discussed. A reasonably complete picture exists of the behaviour of tritiated water (HTO) but information on tritiated gas and methane is less certain. The T/H ratio in water vapour over continental areas is about 3.5 to 4 times that over oceanic areas. ³H can be used for developing chronological information in ice caps at the south pole. Watches with liquid crystal display use ³H. Uncontrolled releases from fuel processing plants could contribute 35-60% of the maximum total ³H body dose (>30mrem/year for a 100m stack). Global models for ³H-concentration are highly dependent on the surface-water depth considered. T/H in the aquatic medium is discussed. In 1972, the oceanic inventory of ³H was approximately 1640MCi (mostly in the Northern Hemisphere), with most of ³H at a depth of less than 1000m. Terrestrially, rapid ³H-loss is mainly due to evapotranspiration. When HTO penetrates more deeply into soil, the residence time increases. ³H-retention in man can be characterized by a summation of 4 exponential terms, with successively increasing half-times.