Sources of He isotopes in groundwaters

Torgersen et al. (1989) further conducted a Ar isotope study on the GAB waters and proposed that radiogenic °Ar could not be entirely sourced from the aquifer rocks and required, as in the case of He, a source external to the aquifer characterized by a 

Assuming that the flux out of the aquifer is null, the general solution is in the form 

Zuber et al. (1997) studied saline waters in Busko Spa (Southern Poland) and argued from stable isotope and NGT data that the shallow water system was recharged during the Quaternary but that waters from the deep system (typically 300-m depth) were recharged in much warmer period, up to 24°C and were pre-Quaternary, implying long residence time ( 5 Ma) for the latter. From the concentration gradient of He between the 

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