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Tritium in a firn core from the coastal zone of Adelie Coast, Antarctica, has been determined by gas-counting after samples were enriched by thermal diffusion. Measurements have been made down to a depth of 10 meters, which corresponds to a water equivalent of 5.35 meters. Each sample represents about 15 cm of water equivalent. Mean annual snow accumlation has been determined by tritium fallout from nuclear tests of 1954 and by radioactive decay of natural tritium. The values found by fallout and by radioactive decay are, respectively, 21 and 20 g cm−2 yr−1. The agreement with data obtained by other methods is very good. Mean natural tritium content at the time of precipitation is 11.3 tritium units (TU), which corresponds to a rate of precipitation of natural tritium of 0.5 tritium atom cm−2 sec−1. Important fluctuations arise in the natural tritium content of precipitation. An attempt to correlate tritium precipitation and solar activity is made difficult by the irregularity of snow accumulation at the site of the core.

Deuterium and tritium measurements were made on firn samples taken along a central axis across Greenland. Accumulation values determined from tritium profiles decrease regularly from 54.7 cm of water per year on the west coast to 18.1 cm of water per year on the east coast. A correlation is demonstrated between the tritium deposition rate and the altitude of the precipitation collection site.