Experimental Sensitivity Analysis of Oxygen Transfer in the Capillary Fringe

Research output: Contribution to journalJournal article – Annual report year: 2014Researchpeer-review

Without internal affiliation

  • Author: Haberer, Christina M.

    University of Tübingen

  • Author: Cirpka, Olaf A.

    University of Tübingen

  • Author: Rolle, Massimo

    University of Tübingen, Denmark

  • Author: Grathwohl, Peter

    University of Tübingen

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Oxygen transfer in the capillary fringe (CF) is of primary importance for a wide variety of biogeochemical processes occurring in shallow groundwater systems. In case of a fluctuating groundwater table two distinct mechanisms of oxygen transfer within the capillary zone can be identified: vertical predominantly diffusive mass flux of oxygen, and mass transfer between entrapped gas and groundwater. In this study, we perform a systematic experimental sensitivity analysis in order to assess the influence of different parameters on oxygen transfer from entrapped air within the CF to underlying anoxic groundwater. We carry out quasi two-dimensional flow-through experiments focusing on the transient phase following imbibition to investigate the influence of the horizontal flow velocity, the average grain diameter of the porous medium, as well as the magnitude and the speed of the water table rise. We present a numerical flow and transport model that quantitatively represents the main mechanisms governing oxygen transfer. Assuming local equilibrium between the aqueous and the gaseous phase, the partitioning process from entrapped air can be satisfactorily simulated. The different experiments are monitored by measuring vertical oxygen concentration profiles at high spatial resolution with a noninvasive optode technique as well as by determining oxygen fluxes at the outlet of the flow-through chamber. The results show that all parameters investigated have a significant effect and determine different amounts of oxygen transferred to the oxygen-depleted groundwater. Particularly relevant are the magnitude of the water table rise and the grain size of the porous medium.
Original languageEnglish
JournalGround Water
Volume52
Issue number1
Pages (from-to)37-49
Number of pages13
ISSN0017-467X
DOIs
Publication statusPublished - 2014
Externally publishedYes
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Water Science and Technology, Computers in Earth Sciences, Anoxic groundwater, Average grain diameter, Biogeochemical process, Flow-through experiments, Ground water table, High spatial resolution, Oxygen concentrations, Shallow groundwater, Experiments, Groundwater, Porous materials, Sensitivity analysis, Oxygen, capillarity, capillary fringe, experimental study, flow velocity, grain size, numerical model, oxygen, porous medium, sensitivity analysis, spatial resolution, water table, ground water, article, chemistry, computer simulation, gas, hydrology, methodology, theoretical model, water flow, Computer Simulation, Gases, Hydrology, Models, Theoretical, Water Movements, GEOSCIENCES, WATER, FLUCTUATING WATER-TABLE, TRAPPED GAS-PHASE, SATURATED POROUS-MEDIA, KINETIC-MODEL, VADOSE ZONE, SAND COLUMN, EXCESS AIR, TRANSPORT, FLOW, GROUNDWATER, S88TT14065 Oxygen, SENSITIVITY analysis

ID: 107288501