Use as an oceanic transient tracer Aside from chlorofluorocarbons, tritium can act as a transient tracer and can "outline" the biological, chemical, and physical paths throughout the world's oceans because of its evolving distribution. Tritium has thus been used as a tool to examine ocean circulation and ventilation and, for such purposes, is usually measured in tritium units, where 1 TU is defined as 1 tritium atom per 10 hydrogen atoms, equal to about 0.118 Bq/liter. As noted earlier, nuclear tests, mainly in the Northern Hemisphere at high latitudes, throughout the late 1950s and early 1960s introduced lots of tritium into the atmosphere, especially the stratosphere. Before these nuclear tests, there were only about 3-4 kg of tritium on the Earth's surface; but these amounts rose by 2-3 orders of magnitude during the post-test period. Some sources reported natural background levels were exceeded by about 1,000 TU in 1963 and 1964 and the isotope is used in the northern hemisphere to estimate the age of groundwater and construct hydrogeologic simulation models. Estimated atmospheric levels at the height of weapons testing to approach 1,000 TU and pre-fallout levels of rainwater to be between 5 and 10 TU. In 1963 Valentia Island Ireland recorded 2,000 TU in precipitation.Wunsch, Carl. (2015). Modern observational physical oceanography : understanding the global ocean. Princeton : Princeton University Press. p. 44 Figure 2.29. .
Use as an oceanic transient tracer Aside from chlorofluorocarbons tritium can act as a transient tracer and can "outline" the biological chemical and physical paths throughout the world's oceans because of its evolving distribution Tritium has thus been used as a tool to examine ocean circulation and ventilation and for such purposes is usually measured in tritium units where 1 TU is defined as 1 tritium atom per 10 hydrogen atoms equal to about 0118 Bq/liter As noted earlier nuclear tests mainly in the Northern Hemisphere at high latitudes throughout the late 1950s and early 1960s introduced lots of tritium into the atmosphere especially the stratosphere Before these nuclear tests there were only about 3-4 kg of tritium on the Earth's surface; but these amounts rose by 2-3 orders of magnitude during the post-test period Some sources reported natural background levels were exceeded by about 1000 TU in 1963 and 1964 and the isotope is used in the northern hemisphere to estimate the age of groundwater and construct hydrogeologic simulation models Estimated atmospheric levels at the height of weapons testing to approach 1000 TU and pre-fallout levels of rainwater to be between 5 and 10 TU In 1963 Valentia Island Ireland recorded 2000 TU in precipitationWunsch Carl (2015) Modern observational physical oceanography  understanding the global ocean Princeton  Princeton University Press p 44 Figure 229 