Variability of Tritium Deposition in Surface Snow Across Antarctica

Partners: GNS Science New Zealand

Tritium is a radioactive isotope of Hydrogen with a relatively short half-life of 12.5 years. It occurs naturally at extremely low levels and is produced when atmospheric particles interact with cosmic rays. Tritium levels can be used to date water samples up to 150 years old with up to seasonal resolution.

Thermonuclear tests in the early 1960s resulted in a human-caused spike in Tritium levels around the world. In Antarctica, these levels were well-established from snow pits taken in the 1970s. However, it has been more than two decades since the bomb-Tritium has been completely removed from the atmosphere (by wash-out and decay). The deposition of natural (cosmogenic) Tritium is not yet well-studied. This cosmogenic Tritium is an effective tool in studying the dynamics of the global water cycle. Therefore, the deposition of Tritium via snow and rain needs to be understood.

The Expedition will create new snow pits at up to 15 sites across Antarctica, and take samples at close intervals (every 2-10cm, depending on the snow thickness of one annual layer at the site). Snow will be contained in specially sealed glass bottles which will protect the integrity of the sample even as it melts into water in higher temperatures. Up to 400 samples will be collected in total from these snow pits.

This research program is in partnership with GNS Science (a New Zealand Crown Research Institute), which houses the world’s most accurate Tritium analysis platform. The next step after the expedition is for the samples to be sent to New Zealand for analysis.