Measurement of the Trititium Concentration in Natural Waters

A method of routine monitoring of tritium in natural waters is described. The water sample to be assayed is electrolyzed from 6 liters a final volume of 5 ml. or less in order to enrich the tritium concentration. The radioactivity of the enriched tritium is measured with the liquid scintillation counter. The degree of tritium enrichment is estimated from the degree of deuterium enrichment, taking into consideration of the relative rate of separation facters of tritium and deuterium by electrolysis.The tritium in the rain and tap water in Osaka city in 1957. and that in the water sampled at the Tamagawa river in Tokyo were assayed with this method, and were found to be in the order of 10-1710-16 as expressed in the atom ratio of tritium to protium(T/H). Although the tritium contents in natural waters may be expected to increase with the repeated nuclear tests, it is found that at least 1000 fold enrichment of tritium is needed for measuring the tritium content in natural waters at the present level with the liquid scintillation counter.