Tritium 3he dating of shallow groundwater
Significant differences between the apparent tritium/ is mainly determined by the ratio of advection to dispersion in water parcels moving away from the water table.
Bosch, “Helium as a Semi-Quantitative Tool for Groundwater Dating in the Range of 104 to 108 Years,” In: Isotopes of Noble Gases as Tracers in Environmental Studies, International Atomic Energy Agency, Vienna, 1992, pp.
After oxidation to HTO, it takes part in the natural water cycle.
Before the full potential of natural tritium as a tracer for water movement in natural systems could be explored its distribution was masked by addition of large amounts of so-called ‘bomb tritium’ produced during the surface tests of nuclear weapons.
These tests which were mainly performed in the early 1960s, led to an increase of tritium in precipitation over the continents of the northern hemisphere from roughly 5 TU to levels of the order of 1000 TU.
One TU (Tritium Unit) means a tritium to hydrogen ratio of 10.This result may be caused by enrichment of local air in CFC-11 and CFC-12 from urban and industrial sources in the northeastern United States and minor contamination from sampling equipment.