HR: 0800h
AN: B31A-0965    [Abstracts]
TI: Mass transfer of electron acceptor aross the capillary fringe
AU: * Liu, S
EM: sanheng.liu@student.uni-tuebingen.de
AF: Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, D-72076, Tuebingen, 72076 Germany
AU: Piepenbrink, M
B31A-0965 AF: Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, D-72076, Tuebingen, 72076 Germany
AU: Grathwohl, P
B31A-0965 AF: Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, D-72076, Tuebingen, 72076 Germany
AB: Transverse dispersion has been identified as a potentially limiting parameter controlling the mixing of electron donors and electron acceptors for natural attenuation of plumes originating from continuously emitting sources, however determining reactive transverse dispersion coefficients is not a simple task. The objective of this work is to elaborate the mass transfer of electron acceptor across the capillary fringe. A two-dimensional numerical reactive transport model and a fully controlled tank experiment are set up to investigate the mass transfer across the capillary and reactive fringe, where the oxygen supply is the limiting factor. The tank (77.9 times 14 times 0.8 cm) is made from acrylic-glass and filled with glass beads (0.5-0.75mm). Sodium dithionite, an easily oxidizable compound, is used as a surrogate for contaminants and is continuously injected from the inlets of the tank and reaches a steady state flow. Air circulates on the top of the glass beads. The oxygen concentrations as well as the reactive products (sulfate) are measured at the outlets of the tank with an oxygen sensor and via IC. In addition to that, resazurine, a redox indicator, is added to visualize the redox zones. These two-dimensional experimental results show quantitatively and qualitatively how the oxygen concentrations decrease at the plume fringe. Two dimensional numerical simulations with Min3P predicted oxygen distributions are compared with the experimental results. Acknowledgements: This work was funded by Helmholtz Association and Helmholtz Research Center UFZ; Project: `Virtual Institute for isotope biogeochemistry-biologically mediated processes at geochemical gradients and interfaces in soil - aquifer systems', Contract VH-VI-155.
DE: 0452 Instruments and techniques
DE: 0466 Modeling
DE: 0471 Oxidation/reduction reactions (4851)
SC: Biogeosciences [B]
MN: Fall Meeting 2005