Determination of HTO content in polar ice/snow samples by low background liquid scintillation technique

Abstract

Tritium (T) is a radio isotope of hydrogen element, which is produced, on the earth, by atomic reactions in artificial atomic reactors as well as in the upper atmosphere. T occurs in natural water mainly as HTO and the concentration in precipitation shows local and seasonal fluctuations depending upon the production and migration processes in the hydrosphere as well as in the atmosphere. The ratio in water vapor (HTO/H_2O) in the atmosphere is not uniform; it is higher in the stratosphere than in the troposphere and also in the northern hemisphere than in the southern hemisphere. A temporal increase was observed in the atmosphere in the 1960's and recorded on the earth in snow layers, stagnant water basins and ground water. The liquid scintillation method has been useful for the determination of tritium content in the liquid phase. The paper discusses the method for the determination of HTO content with the liquid scintillation system LSC-LB3 and significance of the values obtained. The discussion is useful for making the sampling plans in the field and also for detailed interpretation based on the values obtained. HTO content in various water samples in polar regions was introduced; this information is available to investigate snow sedimentary environments in polar regions as well as the water circulation process on the earth.