Applied Geosciences - Geohydromodelling

Reactions in Porous Media

The main aim of the DFG research group "Reactions in Porous Media" is the investigation and analysis of mass transfer limited reactive processes in groundwater at different spatial and temporal scales, such as dissolution of non-aqueous phase liquids (NAPL) across the water-NAPL interface, or microbially mediated degradation of organic contaminant plumes limited by transverse mixing of reaction partners at the plume fringe.

One of the major foci of the CAU Kiel subproject was the numerical evaluation of flow-through tank experiments of conservative and reactive tracer transport in artificial lab-scale sand aquifers aimed at the determination of transverse dispersivities. High-resolution numerical simulations of synthetic tank experiments, where all parameters (porosity, hydraulic conductivity, longitudinal and transverse dispersivities, etc.) are known a priori, were performed with the the OpenGeoSys code (OGS) to assess commonly used parameter estimation approaches. Sensitivity analyses with the numerical model were used to improve the experimental set-up of laboratory tank experiments subsequently performed in collaboration with the Center of Applied Geosciences (University of Tübingen), where conservative tracer transport was studied in homogeneous and heterogeneous porous media and at different flow velocities in order to analyze the tracer mixing behavior.

The second focus of the CAU Kiel subproject was the model based evaluation and interpretation of reactive transport experiments on aromatic hydrocarbon degradation performed at the German Research Center for Environmental Health, Helmholtz Zentrum München. For this purpose, the OGS code was extended by implementation of isotope fractionation as a new reaction process and the MPI-parallelization of the OGS-reaction kernel in order to increase the computational efficiency of the code. Numerical modelling were used as a tool to evaluate a 75 day experiment of transverse dispersion limited aerobic / anaerobic toluene and deuterium labelled ethylbenzene degradation by competitive aerobic and anaerobic (denitrifying) bacterial strains. Reproduction of measured toluene and ethylbenzene concentrations as well as isotope fractionation patterns with the numerical model allowed insight in the spatio-temporal distribution of aerobic and anaerobic biodegradation activity and kinetics of the two competing bacterial strains.

 

Project partners:

  • Kiel University
  • University of Tübingen
  • Helmholtz Centre Munich

Project duration:

July2008 – June 2011

Funding:

This work is a cooperation within the research group ‘‘Reactions in Porous Media’’ (FOR 525/2) funded by the Deutsche Forschungsgemeinschaft.

Project website:

http://gepris.dfg.de/gepris/projekt/5470602

 

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