Tritium, helium isotope and neon data from a multi-level sampling well (DFG 7) at Liedern/Bocholt (West Germany) are presented and discussed. The presence of a radiogenic helium component leads to 3He 4He ratios below that of atmospheric helium (minimum δ3He values ≈ -60%) below about 20 m depth. The 3He profile can be corrected for the nucleogenic 3He component using the neon measurements. Based on the "Vogel" model of a shallow aquifer the tritium/3He distributions are simulated for the years 1987, 2000 and 2025. The model results show that under favourable conditions the tritiogenic 3He peak will be detectable in shallow aquifers for at least the next 4 decades. The influence of the vertical flow velocity and the transversal dispersion coefficient on simulated distributions are estimated. 3He confinement is calculated as a function of the vertical flow velocity and the transversal dispersion coefficient. There is a critical value of the vertical flow velocity (about 0.25-0.5 m/year) below which the 3He loss increases rapidly to high values.
ASJC Scopus subject areas
- Geochemistry and Petrology
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science