Natural hydrogen is an environmentally friendly energy carrier and source that can play a major role in the energy transition. It can be produced by various subsurface geological processes. These include degassing of primordial hydrogen, fluid-rock interactions (e.g. serpentinization) or radiolysis of water. Hydrogen from microbial production probably plays a minor role only. Biological processes are rather involved in the metabolization and thus oxidation of hydrogen in soil.
The aim of this master´s thesis is to investigate the occurrence of natural hydrogen along the southeastern edge of the Bohemian Massif. The study area has been chosen, because it includes two favourable factors for the occurrence of natural hydrogen. Firstly, the Bohemian Massif is made up of the root zone of the Variscan orogen comprised of lithologies with considerable radioactive content. Secondly, the old but still tectonically active, Diendorf fault may provide pathways for fluid migration. Two areas were studied along the Diendorf fault. The Dunkelsteiner Wald area was studied more closely because this section of the Diendorf fault has the highest frequency of recorded earthquakes. The area of Maissau was selected, because of the prominent fault scarp of the Maissauer Berg due to the Diendorf fault.

As part of the study, soil gas measurements were carried out at 763 measurement locations and were subjected to a statistical analysis. The hydrogen concentrations observed in the Dunkelsteiner Wald were higher overall than in Maissau. The statistical analysis was carried out using a Quantile-Quantile (Q-Q) plot to differentiate the nature of the hydrogen concentration signal in the soil. It is possible to distinguish a background signal (H2 ≤ 9 ppm) and a geological signal (H2 > 48 ppm). The transitional interval (10 - 48 ppm H2) in the Q-Q plot is interpreted as a natural influx that is exceeding the hydrogen uptake capacity of the soil. The result of the statistical analysis is then illustrated with spatial referencing.
In the Dunkelsteiner Wald, the background signal is observed directly in the fault zone, while increased (“geologic”) signal values occur in the vicinity of the fault zone. This is probably related to mylonitization in the core of the fault zone, which reduces permeabilities. In contrast, the brittle deformation of the adjacent crystalline rock resulted in the opening of fractures and the creation of pathways. In the Maissau area, this effect is observed in a similar way, but is less pronounced due to the lower overall hydrogen concentrations in the soil.
It was possible to exclude exogenous addition of carbon dioxide, as oxygen and carbon dioxide concentrations indicate biological respiration. As a conclusion, the work conducted in this thesis is not of sufficient extent to derive information about the actual origin of the hydrogen observed by the soil gas measurements, but highlights that natural hydrogen exists along the Diendorf fault and probably migrates to the surface along the zone of brittle deformation.