Redox procecsses in anaerobic aquifers

Redox processes of Iron, Sulfur, and dissolved organic Carbon in anaerobic aquifers (KN 929/2-1)

  • Background

    The role of redox processes along biogeochemical gradients for matter turnover in anaerobic aquifers is only poorly understood. There exists already a lot of information about the interaction of different redox active species, especially of Fe, S, and Carbon, in such systems, but their contribution to electron transfer processes in aquifers is now yet known.
    Within this project, we thus investigate the interaction of reduced sulfur and iron species with natural organic matter (NOM). The work is based on the hypothesis that the re-oxidation of reduced sulfur and iron species on organic matter significantly increases electron accepting capacities in anaerobic systems. This could then explain why in anaerobic systems the oxidation of organic carbon mostly exceeds the electron transfer capacities of commonly investigated inorganic electron acceptors present.
    In particular, we investigate the oxidation of hydrogen sulfide on NOM, the kinetics of this process and the resulting transformation products. Moreover, we study the role of Iron and its interactions in the ternary system Fe-S-NOM. The results of this project will improve our understanding for the competitiveness of the individual redox processes of iron and sulfate reduction, as well as methanogenesis.

  • Methoden

    Most experimental work within the project is carried out in controlled laboratory experiments, as the project requires advanced analytical techniques that cannot be easily applied in the field. In the second phase of the project, however, we plan to increasingly apply our method spectrum to natural samples and biological incubations.
    The analytical methods comprise several common and advanced techniques: spectroscopic characterization of NOM using UV-VIS and fluorescence spectroscopy with subsequent parallel factor analysis (PARAFAC), FTIR spectroscopy, electrochemical characterization (in cooperation with Dr. Michael Sander, ETH Zürich), HPLC and ion chromatography of sulfur species, as well as stable isotope techniques. Within two successful campaigns we could also apply S-K-edge X-ray Absorption Near Edge Structure (XANES) Spectroscopy to study the speciation of sulfur within organic matter.

  • Students

    Currently, there is a master thesis investigating the electrochemical characterization of natural organic matter and ist relation to redox reactions with sulfur and iron (Cand. MSc. Geoökol. Markus Schmitt).

    In summer 2014 there is the possibility to support the project as a student assistant.
    For further information please contact Dr. Klaus-Holger Knorr or Zhiguo Yu.

  • Info

    Project partners, funding, and contacts

    University of Münster
    Institue for Landscape Ecology, Hydrology Group
    Principal Investigator: Dr. Klaus-Holger Knorr
    PhD candidate:  Zhiguo Yu

    University of Bayreuth
    Department of Hydrology
    Project partner: Prof. Dr. S. Peiffer
    Research Unit FOR 580 „Etrap": Electron transfer processes in anoxic aquifers

    ANKA Synchrotron Radiation Facility, SUL-X Beamline
    Dr. Jörg Göttlicher and Dr. Ralph Steininger
    http://www.anka.kit.edu/28.php

    Project duration and funding

    Duration: 06/2009 - 06/2015
    Funded by the German Research Foundation (Deutsche Forschungsgemeinschaft - DFG).

  • News

    Succesful applications for Beamtime at ANKA Synchrotron Facility (Cooperation with Dr. Jörg Göttlicher and Dr. Ralph Steininger):

    • 10/2013 – 04/2014: ISS Karlsruhe, ANKA Beamline SUL-X, Project No. A2013-022-004203 “Redox-speciation of organic sulphur in dissolved and solid peat organic matter - stability of oxidized organic sulfur compounds and implications for anaerobic electron transfer”, PI: KH. Knorr
    • 10/2012 – 03/2013: ISS Karlsruhe, ANKA Beamline SUL-X:, project No. ENV 236: “Speciation of organic sulfur in humic acids and natural organic matter after reaction with H2S”, PI: KH. Knorr