Redox Biogeochemistry
Research in this area is directed towards characterizing the redox properties and reactivities of major organic and mineral geochemical phases in the environment. We combine mediated electrochemical analyses, a novel electrochemical approach developed in our research group, with spectroscopy measurements to determine the capacities of geochemical phases to accept and donate electrons, the reversibility of electron transfer to and from geochemical phases, the reduction potentials at which electrons are transferred.
Geochemical phases under investigation include natural organic matter, both in dissolved and particulate forms, biochar, iron-bearing clay minerals, and, most recently, iron (oxyhydr)oxides. In addition, we study electron transfer to and from lake sediments which contain different redox active species and phases.
Selected key publications are:
Description of mediated electrochemical analyses
Sander, M., T.B. Hofstetter, C.A. Gorski. Electrochemical analyses of redox-active iron minerals: A review of non-mediated and mediated approaches. Environ Sci Technol, 2015, 49, 5862-5878. DOI: external page10.1021/acs.est.5b00006call_made
Aeschbacher, M., M. Sander, and R.P. Schwarzenbach. Novel Electrochemical Approach to Assess the Redox Properties of Humic Substances. Environ Sci Technol, 2010, 44, 87–93; DOI: external page10.1021/es902627pcall_made
Natural organic matter
Wallace, G., M. Sander, Y.-P. Chin, and W. A. Arnold. Quantifying the electron donating capacities of sulfide and dissolved organic matter in sediment pore waters of wetlands. Environmental Sciences: Processes & Impacts. 2017, 19, 758-767, DOI: external page10.1039/C7EM00060Jcall_made
Walpen, N., M. Schroth, M. Sander. Quantification of phenolic antioxidant moieties in dissolved organic matter by flow-injection analysis with electrochemical detection. Environ Sci Technol, 2016, 50, 6423-6432; DOI: external page10.1021/acs.est.6b01120call_made
Poggenburg, C., R. Mikutta, M. Sander, A. Schippers, A. Marchanka, R. Dohrmann, G. Guggenberger. Microbial reduction of ferrihydrite-organic matter coprecipitates by Shewanella putrefaciens and Geobacter metallireducens in comparison to mediated electrochemical reduction. Chemical Geology, 2016, 447, 133-147; DOI: external page10.1016/j.chemgeo.2016.09.031call_made
Wenk, J., M. Aeschbacher, M. Sander, U. von Gunten, and S. Canonica. Photosensitizing and inhibitory effects of ozonated dissolved organic matter on triplet-induced contaminant transformation. Environ Sci Technol, 2015, 49, 8541–8549; DOI: external page10.1021/acs.est.5b02221call_made
L.C. Bodhipaksha, C. M. Sharpless, Y.-P. Chin, M. Sander, W.K. Langston, and A. A. MacKay. Triplet photochemistry of effluent and natural organic matter in whole water and isolates from effluent-receiving rivers. Environ Sci Technol, 2015, 49, 3453–3463. DOI: external page10.1021/es505081wcall_made
Klüpfel, L., A. Piepenbrock, A. Kappler, and M. Sander. Humic substances as fully regenerable electron acceptors in recurrently anoxic environments. Nature Geoscience, 2014, 7, 195-200. DOI: external page10.1038/ngeo2069call_made
Page, S.E., G.W. Kling, M. Sander, K.H. Harrold, J.R. Logan, K. McNeill, and R.M. Cory. Dark formation of Hydroxyl radical in Arctic Soils and Surface waters. Environ Sci Technol, 2013, 47, 12860-12867. DOI: external page10.1021/es4033265call_made
Wenk, J., M. Aeschbacher, E. Salhi, S. Canonica, U. von Gunten, and M. Sander. Chemical oxidation of dissolved organic matter by chlorine dioxide, chlorine, and ozone: Effects on its optical and antioxidant properties. Environ Sci Technol, 2013, 47, 11147-11156. DOI: external page10.1021/es402516bcall_made
Aeschbacher, M., C. Graf, R.P. Schwarzenbach, and M. Sander. Antioxidant properties of humic substances. Environ Sci Technol, 2012, 46, 4916-4925. external pageDOI:call_madeexternal page10.1021/es300039hcall_made
Page, S.E., M. Sander, W.A. Arnold, K. McNeill. Hydroxyl radical formation upon oxidation of reduced humic acids by oxygen in the dark. Environ Sci Technol, 2012, 46, 1590-1597. external pageDOI:call_madeexternal page10.1021/es20386fcall_made
Aeschbacher, M., D. Vergari, R.P. Schwarzenbach, and M. Sander. Electrochemical Analysis of Proton and Electron Transfer Equilibria of the Reducible Moieties in Humic Acids. Environ Sci Technol, 2011, 45, 8385–8394. external pageDOI:call_madeexternal page10.1021/es201981gcall_made
Aeschbacher, M., M. Sander, and R.P. Schwarzenbach. Novel Electrochemical Approach to Assess the Redox Properties of Humic Substances. Environ Sci Technol, 2010, 44, 87–93; external pageDOI: 10.1021/es902627pcall_made
Biochar
Klüpfel, L., M. Keiluweit, M. Kleber, and M. Sander. Redox properties of plant biomass-derived carbon black (biochar). Environ Sci Technol, 2014, 48, 5601-5611. external pageDOI: 10.1021/es500906dcall_made
Iron (oxyhydr-)oxides
Aeppli, M., A. Voegelin; C. Gorski, T. Hofstetter, and M. Sander. Mediated electrochemical reduction of iron (oxyhydr-)oxides under defined thermodynamic boundary conditions. Environ Sci Technol. 2017. asap, DOI: external page10.1021/acs.est.7b04483call_made
Hoving, A. L., M. Sander, C. Bruggeman, T. Behrends. Redox properties of clay-rich sediments as assessed by mediated electrochemical analysis: Separating pyrite, siderite and structural Fe in clay minerals. Chemical Geology, 2017, 457, 149-161; external pageDOI:10.1016/j.chemgeo.2017.03.022call_made
Poggenburg, C., R. Mikutta, M. Sander, A. Schippers, A. Marchanka, R. Dohrmann, G. Guggenberger. Microbial reduction of ferrihydrite-organic matter coprecipitates by Shewanella putrefaciens and Geobacter metallireducens in comparison to mediated electrochemical reduction. Chemical Geology, 2016, 447, 133-147; DOI: external page10.1016/j.chemgeo.2016.09.031call_made
Gorski, G., R. Edwards, M. Sander, T.B. Hofstetter, and S. M. Stewart. Thermodynamic Characterization of Iron Oxide-Aqueous Fe2+ Redox Couples. Environ Sci Technol, 2016, asap; external pageDOI:10.1021/acs.est.6b02661call_made
Iron-bearing clay minerals
Hoving, A. L., M. Sander, C. Bruggeman, T. Behrends. Redox properties of clay-rich sediments as assessed by mediated electrochemical analysis: Separating pyrite, siderite and structural Fe in clay minerals. Chemical Geology, 2017, 457, 149-161; external pageDOI:10.1016/j.chemgeo.2017.03.022call_made
Sander, M., T.B. Hofstetter, C.A. Gorski. Electrochemical analyses of redox-active iron minerals: A review of non-mediated and mediated approaches. Environ Sci Technol, 2015, 49, 5862-5878. DOI: external page10.1021/acs.est.5b00006call_made
Gorski, C.A., L. Klüpfel, A. Voegelin, M. Sander, and T.B. Hofstetter. Redox properties of structural Fe in clay minerals: 3. Relationships between smectite redox and structural properties. Environ Sci Technol, 2013, 47, 13477-13485. external pageDOI: 10.1021/es403824xcall_made
Gorski, C., L. Kluepfel, A. Voegelin, M. Sander, T.B. Hofstetter. Redox properties of structural Fe in clay minerals: 2. Electrochemical and spectroscopic characterization of electron transfer irreversibility in ferruginous smectite, SWa-1. Environ Sci Technol, 2012, 46, 9369-9377. external pageDOI: 10.1021/es302014ucall_made
Gorski, C., M. Aeschbacher, D. Soltermann, A. Voegelin, B. Baeyens, M. Marques Fernandes, T.B. Hofstetter, M. Sander. Redox properties of structural Fe in clay minerals: 1. Electrochemical quantification of electron donating and accepting capacities of smectites. Environ Sci Technol, 2012, 46, 9360-9368. external pageDOI: 10.1021/es3020138call_made
Sediments
Hoving, A. L., M. Sander, C. Bruggeman, T. Behrends. Redox properties of clay-rich sediments as assessed by mediated electrochemical analysis: Separating pyrite, siderite and structural Fe in clay minerals. Chemical Geology, 2017, 457, 149-161; external pageDOI:10.1016/j.chemgeo.2017.03.022call_made
Lau, M., M. Sander, J. Gelbrecht, and M. Hupfer. Spatiotemporal redox dynamics in a freshwater lake sediment under alternating oxygen availabilities: combined analyses of dissolved and particulate electron acceptors. Environmental Chemistry, 2016, external pageasapcall_made
Lau, M., M. Sander, J. Gelbrecht, M. Hupfer. Solid phases as important electron acceptors in freshwater organic sediments. Biogeochemistry, 2015, 123, 49-61. external pageDOI: 10.1007/s10533-014-0052-5call_made
Collaborations
Redox properties of iron-bearing clay minerals and iron (oxyhydr)oxides
external pageThomas B. Hofstettercall_made (Eawag, Switzerland), external pageChristopher A. Gorskicall_made (Penn State University, USA), external pageAndreas Vögelincall_made (Eawag, Switzerland), external pageThilo Behrendscall_made (Utrecht University, The Netherlands)
Redox properties of Natural Organic Matter
external pageSilvio Canonicacall_made (Eawag, Switzerland); external pageUrs von Guntencall_made (Eawag & EPFL, Switzerland), external pageJannis Wenkcall_made (University of Bath, Great Britain), external pageCharles Sharplesscall_made (University of Mary Washington, USA), external pageAndreas Kapplercall_made (Eberhard Karls University Tübingen, Germany), external pageKristopher McNeillcall_made (ETHZ, Switzerland), external pageRose Corycall_made (University of Michigan, USA)
Redox properties of biochar
external pageMarco Keiluweitcall_made (University of Massachusetts, USA); external pageMarkus Klebercall_made (Oregon State University, Switzerland)
Redox properties of Lake Sediments
external pageMaximilian Laucall_made, external pageJörg Gelbrechtcall_made, external pageMichael Hupfercall_made (all IGB Berlin, Germany), external pageBeat Müllercall_made (Eawag, Switzerland)