Tritium from the Molecule to the Biosphere. 1. Patterns of Its Behavior in the Environment

The beta-emitter tritium (3H, the half-life is 12.32 ± 0.02 years) contained in the environment has a natural and technogenic origin. The equilibrium global content of natural tritium is estimated at (1.0–2.6) × 1018 Bq. The total activity of technogenic tritium that was formed as a result of nuclear and thermonuclear weapon tests in 1945–1975 and during the normal and emergency operation of nuclear fuel cycle enterprises reaches 1020 Bq. Anthropogenic tritium serves as a unique marker for generalizing data on the behavior of this radionuclide in different environmental components. This is especially important in view of the intensification of research and development works in the field of controlled thermonuclear fusion in recent years. Promi-sing fusion power reactors, in which it is planned to use a significant amount of 3H as fuel, can become an additional source of impact on the biosphere. Their safety should be assessed, justified, and ultimately ensured based on proper technology and infrastructure. We have analyzed the dynamics of the number of publications on 3H over the period from 1951 to 2021 from the Google Scholar and Clarivate Analytics databases. The main characteristics and chemical forms of tritium are given. The methodology for assessing the content of different forms of 3H in environmental components is given taking into account interlaboratory intercalibration. Pathways of tritium entry into the environment (atmosphere and aquatic and terrestrial ecosystems) as a result of routine and emergency releases and discharges from nuclear industry enterprises are analyzed. Seasonal fluctuations in tritium activity with the maximum level in spring, as well as the effect of climatic factors and distance from the emission source on the spatial distribution of 3H, are shown. The role of soil organic acids in the behavior of tritium in ecosystems is noted. Based on the concept of reference plant and animal species, we have analyzed publications to assess the accumulation of different forms of 3H by biota during laboratory experiments and monitoring studies of natural ecosystems. A number of topical issues that need to be addressed in the near future have been revealed.