Hydrogeology and Biogeochemistry

Our research is related to biogeochemical processes in aquatic ecosystems. Experimental data from laboratory studies as well as detailed observations from natural systems form the basis for interpretation supported and conveyed by application of mathematical modeling.

  • Redox processes within chemical hot spots (Abstract)

Although many studies have investigated the degradation of contaminants in aquatic systems we know only little about the specific process occurring within microbial hot spots. Here we have developed the hypothesis that chemical hot-spots control biogeochemical processes in heterogeneous aquifers (Cooperation with DTU and GEUS, Denmark).

  • Effect of low dissolved organic carbon (DOC) concentrations in shallow and deep groundwater systems (Abstract)

Groundwater systems are generally poor in organic carbon. Therefore it is hard to imagine that the enormous amounts of biomass living in the subsurface depend on the little dissolved DOC. Here we want to study the effect of different electron donor/ acceptor interactions in surface-water and groundwater systems to understand the turnover processes of nitrogen and sulfate in DOC limited aquatic ecosystem. This topic is performed in close cooperation with the Helmholtz Center Munich, Institute of Ecological Chemistry (Dr. Hertkorn, Dr. Schmidt-Kopplin) and the Limnologische Station of TUM (Prof. Geist).

One of our most important tools for the identification and quantification of biogeochemical processes in complex aquifers represents the stable isotope technique. Here we want to investigate the principal mechanism of stable isotope fractionation with focus on the environmental parameters controlling the extent of stable isotope fractionation during denitrification. In cooperation with the Institute of Groundwater Ecology, Helmholtz Center Munich (Dr. Elsner) and international partners we perform laboratory and field experiment to learn more about the use of stable isotopes in biogeochemistry.

  • Modeling of groundwater-plant interactions

 Although plants play an important role in the water cycle and may also significantly impact the fate of substances in the subsurface, feedback mechanisms between plants and hydrological systems have received little attention to date. We therefore aim at coupling dynamic plant uptake models to reactive leaching and groundwater transport simulation (in cooperation with Prof. Mayer, UBC, Canada).

  • Microbial growth and biodegradation coupled to diffusion processes and plant uptake

 Biodegradation of contaminants at the field-scale is often limited. Therefore contaminants present in soil or groundwater may pose considerable threats to ecosystems and human health. Our aim is to investigate contaminant fate in the soil-groundwater-plant systems. Experiments and field observations are analyzed mathematically in order to understand and describe relevant processes and parameters driving and limiting biodegradation. Investigations are performed in cooperation with DTU, Denmark (Prof. Trapp) and UFZ, Leipzig (Prof. Kästner).

Geothermal Energy

The topic „Geothermal Energy" has gain enormous interest during the last decades since it is an attractive resource of energy (see Projects). The use of geothermal energy leads to the substitution of fossil fuels and, accordingly, to the reduction of CO2 emission. Depending on the drilling depth, there are two possibilities to extract geothermal energy:

  • shallow geothermal energy (< 400 m)
  • deep geothermal energy (> 400m)

While installations of shallow geothermal energy systems increase, there are still uncertainties, which prevent the use of geothermal energy to tap its full potential. These uncertainties are due to insufficient accuracy of the subsurface modeling, which determine the performance of a geothermal energy system. Aim of the research is the accurate prediction of the long-term behavior of geothermal potentials.

The research on deep geothermal energy targets to increase the knowledge of flow rates and groundwater temperature in deep aquifers and to improve the methods to assess and predict these parameters. Field works are carried out to collect hydraulic and thermal data. Empirical and statistical analysis, analysis of tectonic processes, 3D-geological modeling and numerical simulations including heat transport processes are performed to achieve profound understanding of thermal behavior of the subsurface.

The research in the field of shallow geothermal energy includes the investigation of heat and fluid transport processes and the assessment of the related principle parameters such as thermal conductivity and thermal capacity of various natural matrices and technique materials. In this context, the research activities involve also the improvement of parameter assessment technique in the field and laboratory. Numerical heat transport models are used to simulate the geothermal installations under different conditions. Following are the main focuses of the research in the field of shallow geothermal energy:

  •  Assessment of the interaction between geothermal installations and the subsurface

  • Effect of geothermal use on groundwater

  • Improvement of the prediction method based on the numerical technique comparing/coupling different softwares
biogeochemistry as an interface of hydrosphere, lithosphere, biosphere and atmosphere