Determination of low HTO content in various water samples by liquid scintillation technique with electrical condensation procedure

Abstract

Tritium (T) is one of the hydrogen isotopes, composing water molecules designated HTO, and is useful as a tracer of water origin and circulation. T has been produced as fission debris, and is also produced naturally in the stratosphere by the interaction of cosmic radiation with air atoms. HTO is introduced into the water circulation process in the earth, where T is diminished by nuclear decay. Higher HTO content in the water occurs in the direct deposition from the atmosphere. Lower HTO content occurs in the water reservoirs where the residence time of water is longer such as ocean. The deposition, consist of the water vapor from the oceanic origin, has also lower HTO content. The content in sea ice depends on the origin of water, oceanic or atmospheric. This paper discusses the method for the HTO measurement of natural water with lower HTO content, including the procedure of the condensation and distillation. The water samples in the polar region have various HTO content and the analytical time, ranged from several days to several months, depends mainly on HTO content. The proposal on the procedure of the measurement, depending on the samples in various water reservoirs in the polar region, is available for conducting the analytical plan for water samples in the natural environments with the various residence times, especially for the samples under low HTO content.