TRITIUM IN THE GLOBAL ATMOSPHERE - DISTRIBUTION PATTERNS AND RECENT TRENDS

Temporal and spatial variations of tritium in the global atmosphere during the past three decades are discussed, with emphasis on the tritium content of monthly precipitation, as derived from the database of the IAEA/WMO global network "Isotopes in Precipitation". Whereas the tritium levels in precipitation have, in recent years, returned close to natural, pre-bomb values in most parts of the world, the technogenic emissions of tritium are becoming more and more visible. The most important sources of technogenic tritium are nuclear facilities as well as manufacturing and disposal of luminous consumer products. Examples of local and regional scale contamination of the lower troposphere due to ground-level tritium releases are presented.