Tritium measurements in water on Mt. Etna by liquid scintillation counting

Tritium exists rather uniformly in the environment as a result of both natural production by cosmic-ray interaction with the upper layers of the atmosphere and residual fallout from nuclear-weapons tests carried out from 1952 till 1980. Naturally occurring tritium mainly reaches the Earth's surface in the form of precipitation, becoming part of the hydrological cycle. Nowadays, the possibility of measuring the low level of tritium radioactivity gives a chance to use tritium as a natural tracer in water systems. This paper presents results from a first survey carried out in the north-west flank of Mt. Etna and in the southern side of Nebrodi, in order to validate a procedure developed for the determination of tritium activity concentrations in water samples by liquid scintillation counting. The investigated areas show low tritium concentrations, much below the Italian limit of 100 Bq/l for drinking water and even comparable with the minimum detectable activity value. The effective dose due to tritium consumption is also calculated.