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Abstract

The closed-system equilibration (CE) model for the description of dissolved noble gas concentrations in groundwater proved to be able to provide good fits to measured concentrations as well as physically reasonable parameter estimates in a variety of studies. Sometimes, however, the CE model yields unrealistically high values of the temperature (T) and “excess air” (A) parameters in combination with high temperature uncertainties. In this thesis the origin of these problems is analyzed as well as possible solutions. It is shown that increased argon concentrations in combination with decreased xenon can cause the observed problems and it is demonstrated how Monte Carlo simulations may be employed to still acquire realistic results. Step-by-step instructions are given for the practical application of this new type of method, indicating when to use Monte Carlo simulations and showing how to carry them out. Taking into account these new insights, a re-evaluation of ten studies from the literature is carried out. The results of most studies were confirmed. For some cases, however, deviations from the original statements were found. The thesis concludes with a description of the software PANGA, which was developed to allow for an easy-to-use application of the described evaluation methods to measured noble gas data sets.