Eric Roden

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TEAPREVU: A numerical simulation model of Terminal Electron-Accepting Processes in a Representative Elementary Volume of Uranium-contaminated subsurface sediment. Prepared for U.S. DOE Natural and Accelerated Bioremediation Program. E.E. Roden, Y. Fang, T. D. Scheibe, S. C. Brooks, and W. D. Burgos (January 2005).

Numerical Model of Sediment Diagenesis and Hg Speciation. Prepared for NSF Biocomplexity in the Environmental Proposal “Biocomplexity of mercury methylation: genomic to ecosystem approaches toward a predictive model”. C. Gilmour, PI/PD; A. Heyes, R.P. Mason, M.T. Suzuki, E.E. Roden, G.R. Aiken, R.A. Bodaly, and R.C. Harris, Co-PIs (January 2003).

Reactive Transport Simulation of Microbial Redox Processes and Coupled Fe-S-As Biogeochemistry in Alluvial Aquifer Sediments. Prepared for NSF Biocomplexity in the Environmental Proposal “Environmental implications of the coupled biogeochemical cycles of iron and arsenic”, J. Saunders, PI/PD; M.K. Lee, C. Morton, M.O. Barnett, E.E. Roden, C. Zheng, Co-PIs (March 2001).

Numerical Simulation of U(VI) Reductive Immobilization in Fe(III) Oxide-Reducing Subsurface Sediments. Prepared for U.S. DOE Environmental Management Science Proposal “Reductive immobilization of U(VI) in Fe(III) oxide-reducing subsurface sediments: analysis of coupled microbial-geochemical processes in experimental reactive transport systems”, E.E. Roden, PI/PD; M.M. Urrutia, M.O. Barnett, and C.J. Lange, Co-PIs. (March 2000).

Reactive Transport Simulation of U(VI) Reductive Immobilization in Fe(III) Oxide-Reducing Subsurface Sediments. Prepared for U.S. Department of Energy, NABIR Program, Biogeochemical Dynamics Element Proposal “The Effect of Spatial Variability in the Distributions of Metal Reducing Bacteria and Sediment Properties on Immobilization of Uranium(VI) in Groundwater Plumes”, C.J. Murray, PI/PD; T. Scheibe, E.E. Roden, S. Hubbard, and P. Jaffe, Co-PIs. (February, 2000).

Roden, E.E. Rate-limiting step of dissimilatory microbial iron oxide nanoparticle reduction. American Chemical Society National Meeting, Atlanta, GA, August 2021.

Roden, E.E. Extracellular biological redox transformation of insoluble Fe-bearing minerals in soil and sedimentary environments. Marion L. and Chrystie M. Jackson Mid-Career Clay Scientist Award Lecture, Clay Minerals Society Annual Meeting, Richland WA, June 2020.

“Extracellular electron transfer (EET) in the critical zone: biological redox transformation of insoluble Fe-bearing minerals in soil and sedimentary environments”. Adrian Smith Lecture in Environmental Geochemistry, University of Waterloo, Department of Earth Sciences, Waterloo, Ontario, Canada, April 2020. (postponed due to Covid)

Roden, E.E. Rate-limiting step of dissimilatory microbial iron oxide nanoparticle reduction. American Chemical Society National Meeting, Philadelphia, PA, April 2020.

Yang, Y., D. Adhikari, Zhao, Q., Dunham-Chetham, S., Das, K, Mejia, J., R. Huang, Wang, X., Poulson, S., D. Obrist, E.E. Roden, Y. Yang, Tang, Y, Obrist, D., Roden, E.E.. Biogeochemical stability and reactions of iron-organic carbon complexes. American Geophysical Union Fall Meeting, New Orleans, December 2017.

Roden, E.E. Microbial Iron Redox Metabolism in Circumneutral pH Environments. American Geophysical Union Fall Meeting, December 2016.

Roden, EE. Metagenomic analysis of extracellular electron transfer (EET) mechanisms in novel enrichment cultures. Workshop on U.S.–China Collaborative Research on Microbe–Mineral Interactions: Microbial Extracellular Electron Transfer with Minerals as Electron Sources and Sinks, March 2015.

Roden, EE. Microbial iron redox cycling in circumneutral pH terrestrial environments. American Geophysical Union Fall Meeting, December 2014.

Roden, E.E. Geochemical and microbiological complexity in soil-sediment redox oscillations. Complex Soil Systems Conference, September 2014.

Percak-Dennett, E. Roden, H. Xu, H. Konishi, C. Chan, A. Bhattacharyya and T. Borch. Microbial chemolithoautotrophic oxidation of pyrite at neutral pH. Goldschmidt Conference, June 2014.

Roden, E.E. Microbial iron redox cycling in sedimentary environments. American Chemical Society National Meeting, April 2013.

Roden, E.E. Microbial iron redox cycling in sedimentary environments. International Workshop on Iron Biogeochemistry, Monte Verita (Ascona), Switzerland, March 2013.

Roden, E.E. Microbial oxidation of insoluble Fe(II)-bearing minerals relevant to the Hanford 300 Area and other subsurface environments. U.S. Department of Energy, Subsurface Biogeochemistry Program Annual PI Meeting, April 2012.

Roden, E.E. and E. Shelobolina. Microbial iron redox cycling in subsurface environments. Biochemical Society (UK) Conference on “Electron transfer at the microbe-mineral interface”, Norwich, UK, April 2012.

Roden, E.E. Repeated anaerobic microbial redox cycling of iron. NSF-sponsored workshop on “Iron in Coastal Streams”, June 2011.

Roden, E.E. Physiology-based models of microbial redox metabolism. U.S. Department of Energy, Subsurface Biogeochemistry Program Annual PI Meeting, April 2011.

Roden, E.E. Microbially-mediated anaerobic redox cycling of iron in sediments: pathways and biogeochemical significance. Duquesne University Minisymposium on Metals in Biological Systems, December 2010.

Roden, E. New mechanisms and microorganisms associated with extracellular Fe redox metabolism. University of Wisconsin, Department of Bacteriology Raper Symposium, August 2010.

Roden E., A. Kappler, I. Bauer, J. Jiang. A. Paul, R. Stoesser, H. Konishi, and H. Xu. Microbial reduction of solid-phase humic substances and electron shuttling to Fe(III) oxide. Goldschmidt Conference, June 2010.

Shelbolina E., H. Xu, H. Konishi, R. Kukkadapu, T. Wu, and E. Roden. Microbial oxidation and mineralogical alteration of biotite. Goldschmidt Conference, June 2010.

Wu, T., E. Shelobolina, R. Kukkadapu, and E. Roden. Experimental studies of microbial Fe(III)-phyllosilicate reduction in subsurface sediments. Goldschmidt Conference, June 2010.

Roden, E.E. Microbial Fe(II) oxidation and mineralization in sediments of an acidic, hypersaline lake (Lake Tyrell, Victoria, Australia). Second U.S.-China Geomicrobiology Workshop, May 2010.

Picardal, F., Shelobolina, E., Xu, H., Roden, E. Microbially-mediated anaerobic redox cycling of iron and nitrogen in sediments. Goldschmidt Conference, June 2009.

Roden E., A. Kappler, I. Bauer, J. Jiang. A. Paul, and R. Stoesser. Solid-phase humic material as a microbial electron acceptor and electron shuttle to Fe(III) oxide. Wetland Biogeochemistry Symposium, June 2009.

Shelobolina, E., M. Blöthe, H. Konishi, H. Xu, and E. Roden. Microorganisms involved in iron redox cycling in smectite. American Chemical Society National Meeting, March, 2009.

E.E Roden, M. Blothe, G. Tangalos, E. Freeman, H. Xu, J. Eigenbrode, V. Gillerman. Weathered volcanic tuff in Box Canyon, ID as an analog to ancient weathering environments on Mars. NASA Astrobiology Science Conference (AbSciCon), April 2008.

Roden, E.E. Anaerobic redox cycling of iron in sediments: pathways and biogeochemical significance. American Chemical Society National Meeting, September 2006.

Roden, E.E. Kinetic and thermodynamic controls on microbial Fe(III) oxide reduction. Telluride Research Science Center Workshop on Iron Redox Chemistry at Environmentally Relevant Surfaces, Telluride, CO, July 2006.

Roden, E.E. Microbially-mediated anaerobic redox cycling of iron in sediments and culture. American Society for Microbiology Annual Meeting, Washington, DC, May 2006.

Roden, E.E. Geochemical controls on microbial Fe(III) oxide reduction kinetics. American Chemical Society National Meeting, Atlanta, GA, March 2006.

Roden, E.E. A general rate law for bacterial Fe(III) oxide reduction. 15th Annual Goldschmidt Conference, Moscow, ID, May 2005.

Roden, E.E. Geochemical and microbiological controls on dissimilatory iron reduction. French Academy of Sciences, Colloquium on the Biogeochemistry of the cycle of iron; green rusts and fougerite (Biogéochimie du cycle du fer – Rouilles Vertes et fougérite), Paris, December 2004.

Roden, E.E. 2004. Analysis of FeIII oxide reactivity toward long-term bacterial vs. chemical reduction. 11th International Symposium on Water-Rock Interaction, Saratoga Springs, NY, June 2004.

Roden, E.E. 2004. Surface chemical and thermodynamic controls on bacterial metal reduction in subsurface environments. U.S. Federal Interagency Workshop on Conceptual Model Development for Subsurface Reactive Transport Modeling of Inorganic Contaminants, Radionuclides, and Nutrients, Albuquerque, NM, April 2004.

Roden, E.E. 2004. U(VI) reduction at the solid-water interface. U.S. Department of Energy, Natural and Enhanced Bioremediation Annual PI Meeting, Warrenton, VA, March 2004.

Roden, E.E. 2003. Thermodynamic versus surface area control of microbial Fe(III) oxide reduction kinetics. American Geophysical Union Fall Meeting, San Francisco, CA, December 2003.

Roden, E.E. 2003. Geochemical and microbiological controls on dissimilatory iron reduction. International Workshop on Biogeochemical Processes Involving Iron Minerals in Natural Waters, Monte Verita (Ascona), Switzerland, November 2003.

Roden, E.E. 2003. Coupled microbial Fe(III) oxide reduction and uranium(VI) reduction in subsurface sediments. U.S. Department of Energy, Natural and Enhanced Bioremediation Field Research Center Workshop, Oak Ridge National Laboratory, Oak Ridge, TN, September 2003.

Roden, E.E. 2003. Microbial Fe(III) oxide reduction: an obvious choice for mesoscale experiments and numerical modeling. U.S. Department of Energy, Idaho National Engineering and Environmental Laboratory Workshop on Mesoscale Subsurface Science Research, Salt Lake City, UT, August 2003.

Roden, E.E. 2003. Reactive transport modeling of microbial-geochemical interactions in the subsurface: coupled Fe(III) oxide/uranium(VI) reduction. U.S. Department of Energy, Basic Energy Sciences Workshop on Integrating Numerical Models of Reactive Flow and Transport into Fundamental Geoscience Research, Carmel Valley, CA, June 2003.

Roden, E.E. and K.A. Weber. 2003. Nitrate-dependent Fe(II) oxidation in surface and subsurface sediments. American Society for Microbiology Annual Meeting, Washington, DC, May 2003.

Roden, E.E. and K.A. Weber. 2003. Influence of nitrate on iron redox cycling and mineralogy in freshwater sediments. Clay Society and Mineralogicial Society of America Classic Clays and Minerals Conference, Athens, GA, June 2003.

Roden, E.E. and K.A. Weber. 2002. Microbial nitrate-dependent oxidation of solid-phase Fe(II). American Chemical Society National Meeting, Orlando, FL, April 2002.

Roden, E.E., D. Sobolev, and G.W. Luther III. 2001. Evidence for rapid microscale redox cycling of iron in circumneutral environments. International Sympsosium on Microbial Ecology, Amsterdam, The Netherlands, September 2001.

Warner, K.A., E.E. Roden, and J.C. Bonzongo. 2001. Effects of different electron accepting conditions on net microbial mercury methylation potential in mineral-rich sediments. Workshop on the Fate, Transport, and Transformation of Mercury in Aquatic and Terrestrial Environments. West Palm Beach, FL, May 2001.

Roden, E.E. and D. Sobolev. 2000. Coupled microbial Fe(II) oxidation Fe(III) reduction at redox interfaces: potential for rapid microscale cycling of iron. American Geophysical Union Fall Meeting, San Francisco, FL, December 2000.

Roden, E.E. and F.G. Ferris. 2000. Immobilization of aqueous stronium during carbonate mineral formation coupled to microbial Fe(III) oxide reduction. Symposium on Chemical-Biological Interactions in Contaminant Fate, American Chemical Society National Meeting, Washington, DC, August 2000.

Roden, E.E. 2000. Kinetics of microbial Fe(III) oxide reduction in freshwater wetland sediments. American Society of Limnology and Oceanography Aquatic Sciences Meeting, Copenhagen, Denmark, June 2000.

Warner, K.A., E.E. Roden, and J.C. Bonzongo. 2000. Microbial mercury methylation and demethylation potential rates under different electron accepting conditions in mineral-rich wetland sediments. American Society of Limnology and Oceanography Aquatic Sciences Meeting, Copenhagen, Denmark, June 2000.

Roden, E.E. 1999. Microbial and geochemical controls on bacterial Fe(III) oxide reduction: links between surface chemistry and microbial physiology. Gordon Conference on Applied and Environmental Microbiology, June 1999.

Roden, E.E. 1997. Organic carbon oxidation coupled to microbial Fe(III) oxide reduction in freshwater wetland sediments. American Society for Microbiology Annual Meeting, Miami, FL, May 1997.

Roden, E.E. 1997. Geochemical and microbiological controls on bacterial iron oxide reduction. Geological Society of America Southeastern Region Annual Meeting, Auburn, AL, September 1997.

Roden, E.E. M.M. Urrutia, and J.M. Zachara. 1996. Surface area and microbiological controls on Fe(III) oxide reduction. American Chemical Society, Industrial and Environmental Chemistry Division Special Session on Emerging Technologies in Hazardous Waste Management, Atlanta, GA, October 1996.

Roden, E.E. 1996. Influence of anaerobic microbial metabolism on phosphate mobility in wetland sediments. Annual Meeting of the Soil Science Society of America, Indiapolis, IN, November 1996.

Roden, E.E. 1996. Fe(III) oxide reduction in wetland sediments. Fourth Symposium on Biogeochemistry of Wetlands, New Orleans, LA, March 1996.

Roden, E.E. 1995. Microbial Fe(III) oxide reduction and Fe cycling in iron-rich freshwater wetland sediment. American Chemical Society, Industrial and Environmental Chemistry Division Special Session on Emerging Technologies in Hazardous Waste Management, Atlanta, GA, October 1995.

Roden, E.E. and Y.A. Gorby. 1994. Microbial reduction of crystalline Fe(III) oxides and structural Fe(III) in layered clay minerals. American Chemical Society, Industrial and Environmental Chemistry Division Special Session on Emerging Technologies in Hazardous Waste Management, Atlanta, GA, October 1994.

Roden, E.E. 1990. Carbon cycling in mesohaline Chesapeake Bay sediments. New perspectives in the Chesapeake system 1990: proceedings of a conference. Chesapeake Research Consortium, November 1990.

CONTRIBUTED PRESENTATIONS AT SCIENTIFIC CONFERENCES:

Roden, E.E. and B.H. Jeon. 2004. Biological versus chemical reduction of U(VI) at the solid-water interface. American Society for Microbiology General Meeting, May 2004.

Roden, E.E. and E. Sedo. 2003. Framework for numerical simulation of bacterial Fe(III) oxide reduction in circumneutral soil and sedimentary environments. American Geophysical Union Fall Meeting, December 2003.

Roden, E.E. 2003.  Control of iron redox cycling in freshwater wetland sediments by microscale Fe(II)-O2 reaction dynamics at the sediment-water interface. American Society of Limnology and Oceanography Aquatic Sciences Meeting, February 2003.

B.H. Jeon and E.E. Roden. 2003. Reductive immobilization of U(VI) at the oxide-water interface. American Chemical Society National Meeting, March 2003.

Roden, E.E. and T.D. Scheibe. 2002. Multiple pore region model of uranium(VI) reductive immobilization in structured subsurface media. American Geophysical Union Fall Meeting, December 2002.

Wildung, R.E., S.W.  Li, C.J. Murray, K.M. Krupka, Y. Xie, N.J. Hess, and E.E. Roden. 2002. Technetium reduction in sediments of a shallow aquifer exhibiting dissimilatory iron reduction potential:  influence of sediment physicochemical properties. International Society for Subsurface Microbiology Meeting, August 2002.

Overstreet, K.B., E.E. Roden, and C.J. Murray. 2001. Bacterial Fe(III) oxide reduction in intact coastal plain aquifer sediments. Geological Society of America Annual Meeting, October 2001.

Murray, C.J., Y.L. Xie, E.E. Roden, and K.B. Overstreet. 2001. Microbial reduction potential in coastal plain sediments. Geological Society of America Annual Meeting, October 2001.

Barnett, M.O., E.E. Roden, P.M. Jardine, S.C. Brooks. 2001. Biogeochemical interactions of U and Fe(III) oxides in subsurface environments: modeling and experimental results. American Chemical Society National Meeting, August 2001.

Roden, E.E. and D. Sobolev. 2001. Numerical simulation of bacterial Fe Redox cycling in experimental culture systems.  American Society for Microbiology General Meeting, May 2001.

Sobolev, D. and E.E. Roden. 2001. Phylogenetic and physiological characterization of a neutrophilic lithotrophic Fe(II)-oxidizing bacterium isolated from wetland sediments. American Society for Microbiology General Meeting, May 2001.

Weber, K.A. P.F. Churchill, and E.E. Roden. 2001. Microbial community structure associated with the interaction between nitrogen and iron redox cycles in freshwater sediments. American Society for Microbiology General Meeting, May 2001.

Roden, E.E. and D. Sobolev. 2000. Suboxic deposition of ferric iron by bacteria in opposing gradients of Fe(II) and oxygen at circumneutral pH. American Society of Limnology and Oceanography Aquatic Sciences Meeting, June 2000.

Roden, E.E. 2000. Direct evidence for microbial reduction of solid-phase humic substances in freshwater wetland sediments. American Society for Microbiology Annual Meeting, May 2000.

Sobolev, D. and E.E. Roden. 2000. Interaction between Fe(III)-reducing and Fe(II)-oxidizing bacteria: potential for microscale microbial cycling of iron. American Society for Microbiology Annual Meeting, May 2000.

Weber, K.A., M.R. Leonardo, and E.E. Roden. 2000. Ferrous iron oxidation coupled to nitrate reduction by dissimilatory iron-reducing bacteria. American Society for Microbiology Annual Meeting, May 2000.

Baer, M.L., E.E. Roden, and P.F. Churchill. 2000. Analysis of successional changes within a natural microbial biofilm community using denaturing gradient gel electrophoresis. American Society for Microbiology Annual Meeting, May 2000.
Roden, E.E., M.R. Leonardo, V.K. Keith, and F.G. Ferris. 1999. Immobilization of aqueous strontium during carbonate mineral formation coupled to microbial Fe(III) Oxide Reduction. International Society for Subsurface Microbiology Meeting, August 1999.

Roden, E.E. and F.G. Ferris. 1999. Immobilization of aqueous stronium during carbonate mineral formation coupled to microbial Fe(III) oxide reduction. International Symposium on Environmental Biogeochemistry, October 1999.

Roden, E.E. and R.G. Wetzel. 1999. Humic substances accelerate microbial reduction of amorphous Fe(III) oxide in aquatic sediments. American Society for Microbiology Annual Meeting, May 1999.

Keith, V.K. and E.E. Roden. 1999. Immobilization of aqueous strontium during bacterial reduction of synthetic Fe(III) oxides. American Society for Microbiology Annual Meeting, May 1999.

Jackson, C.R., E.E. Roden, and P.F. Churchill. 1999. Changes in bacterial community structuree during freshwater biofilm development. American Society for Microbiology Annual Meeting, May 1999.

Weber, K.A. and E.E. Roden. 1999. Biologically-catalyzed nitrate-dependent oxidation of microbially-reduced Fe(III) oxides. American Society for Microbiology Annual Meeting, May 1999.

Sobolev, D. and E.E. Roden. 1999. Molecular characterization of microaerophilic autotrophic Fe(II)-oxidizing enrichment cultures growing at circumneutral pH. American Society for Microbiology Annual Meeting, May 1999.

M.R. Leonardo, F.G. Ferris, and E.E. Roden. 1999. Sr2+ immobilization by authigenic carbonate precipitation under iron-reducing conditions. American Society for Microbiology Annual Meeting, May 1999.

Roden, E.E. 1999. Modeling iron cycling and the influence of microbial iron oxide reduction on methane production in freshwater wetland sediments. American Society of Limnology and Oceanography Aquatic Sciences Meeting, February 1999.

Leonardo, M.R. F.G. Ferris, and E.E. Roden.  1998.  Analysis of iron-carbonate mineral formation during microbial reduction of synthetic amorphous iron oxide.  American Society for Microbiology Annual Meeting, May 1998.

May, T.M. and E.E. Roden.  1998.  3H-Leucine incorporation by Fe(III)-reducing bacteria.  American Society for Microbiology Annual Meeting, May 1998.

Roden, E.E. and M.M. Urrutia.  1998.  Microbial Fe(III) oxide reduction in open experimental systems.  American Society for Microbiology Annual Meeting, May 19998.

Sobolev, D. and E.E. Roden.  1998.  Iron-oxidizing bacteria in opposing gradients of ferrous iron and oxygen.  American Society for Microbiology Annual Meeting, May 1998.

Weber, K.A. and E.E. Roden.  1998.  Interaction of nitrate reduction and Fe(III) oxide reduction in freshwater wetland sediments.   Annual Water Resources Conference of the American Water Resources Association, October 1998.

Weber, K.A. and E.E. Roden.  1998.  Interaction of nitrate reduction and Fe(III) oxide reduction in freshwater wetland sediments.   American Society for Microbiology Annual Meeting, May 1998.

May, T.M. and E.E. Roden.  1998. Models of the activity and growth of Fe(III)-reducing bacteria.  Annual Water Resources Conference of the American Water Resources Association., October 1998.

Howell, R., R.J. Donahoe, and E.E. Roden.  1997.  Effects of microbial iron oxide reduction on pH and alkalinity in anaerobic bicarbonate-buffered media.  American Geophysical Union Fall Meeting, December 1997.

Roden, E.E. and M.M. Urrutia.  1997.  Microbial Fe(III) oxide reduction in aquatic sediments: new insights into control and significance in biogeochemical fluxes.  International Symposium on Environmental Biogeochemistry, October 1997.

Warren, L.A., F.G. Ferris, and E.E. Roden.  1997. Strontium reactions at Shewanella and hydrous ferric oxide surfaces.  Geological Society of America Annual Meeting, October 1997.

Roden, E.E. and R.G. Wetzel. 1997.  Iron oxide suppression of methane production in freshwater wetland sediments.  American Society for Limnology and Oceanography Aquatic Sciences Meeting, June 1997.

Urrutia, M.M. and E.E. Roden. 1997.  Growth parameters of Fe(III)-reducing bacteria on soluble and solid-phase Fe(III) oxides. American Society for Microbiology Annual Meeting, May 1997.

Coates, J.D., D.J. Ellis, E.L. Blunt-Harris, C.V. Gaw, E.E. Roden, and D.R. Lovley.  1997.  Recovery of humics-reducing bacteria from a diversity of environments.  American Society for Microbiology Annual Meeting, May 19997.

Urrutia, M.M., J.M. Zachara, and E.E. Roden. 1996.  Influence of Al oxides and clay minerals on bacterial Fe(III) oxide reduction in anaerobic environments.  Soil Science Society of America Annual Meeting, November 1996.

Roden, E.E. 1996. Rapid Fe cycling in freshwater wetland sediments.  American Society for Microbiology Annual Meeting, March 1996.

Urrutia, M.M., E.E. Roden, and J.M. Zachara. 1996.  Mechanisms of chelator stimulation of microbial Fe(III) oxide reduction.  American Society for Microbiology Annual Meeting, May 1996.

May, T. and E.E. Roden. 1996. Microbial iron cycling in freshwater wetland sediments.  Fourth Symposium on Biogeochemistry of Wetlands, March 1996.

Edmonds, J.W. and E.E. Roden. 1996. Relative influence of direct microbial Fe(III) oxide reduction vs. iron-sulfide mineral formation on phosphorus mobilization in freshwater wetland sediments.  Fourth Symposium on Biogeochemistry of Wetlands, March 1996.

Jones, S.C., R. Donahoe, and E.E. Roden. 1996. Iron and iron-reducing bacteria: their distribution within a freshwater riparian wetland system.  Fourth Symposium on Biogeochemistry of Wetlands, May 1996.

Roden, E.E and R.G. Wetzel. 1996. Fe(III) oxide regulation of methane production in freshwater wetland sediments.  Fourth Symposium on Biogeochemistry of Wetlands, March 1996.

Urrutia, M.M. E.E. Roden, and J.M. Zachara. 1995. Microbial and geochemical controls on dissimilatory Fe(III) reduction.  American Chemical Society, Industrial and Environmental Chemistry Division Special Session on Emerging Technologies in Hazardous Waste Management, October 1995.

Roden, E.E. and R.G. Wetzel. 1995. Regulation of methane flux from freshwater wetland sediments by competing anaerobic microbial processes.  International Association of Theoretical and Applied Limnology International Congress, July 1995.

Edmonds, J.W. and E.E. Roden.  1995. Relative influence of direct microbial Fe(III) oxide reduction vs. Fe-S mineral formation on phosphorus mobilization in freshwater wetland sediments.  American Society of Limnology and Oceanography Annual Summer Meeting, June 1995.

Roden, E.E. and R.G. Wetzel. 1995.  Regulation of methane production in freshwater wetland sediments by competing anaerobic microbial processes.  American Society of Limnology and Oceanography Annual Summer Meeting, June 1995.

Wen, M.H., C.R. Lange, F.J. Molz, and E.E. Roden. 1995. Multi-component reactive transport modeling in perched wetland soils.  American Geophysical Union Spring Meeting, April 1995.

Roden, E.E., J.M. Zachara, J.K. Fredrickson, and Y.A. Gorby. 1994. Reduction of synthetic and soil crystalline Fe(III) oxides by a dissimilatory Fe(III)-reducing bacterium.  American Society for Microbiology Annual Meeting, May 1994.

Roden, E.E. and D.R. Lovley. 1991. Iron diagenesis in surficial freshwater Potomac River sediments.  International Estuarine Research Federation Conference, October 1991.

Marvin, M.C., E.E. Roden, and D.G. Capone. 1991. Temporal and spatial variation in benthic microbial respiration in the mainstem of the Chesapeake Bay. American Society of Limnology and Oceanography Annual Meeting, February 1991.

Cornwell, J.C., E.E. Roden, P.A. Sampou, and D.G. Capone. 1990. Formation and distribution of iron sulfide minerals in Chesapeake Bay sediments.  Annual Meeting of the American Chemical Society, August 1990.

Roden, E.E. and J.H. Tuttle. 1990. Rapid turnover of inorganic sulfur in oligohaline Chesapeake Bay sediments.  American Geophysical Union Ocean Sciences Meeting, February 1990.

Tuttle, J.H., E.E. Roden, C.L. Divan, J.T. Bell, D.G. Cargo, and R.B. Jonas. 1988. Bacterial processes leading to the formation and maintenance of anoxia in Chesapeake Bay. American Geophysical Union Ocean Sciences Meeting, February 1988.

Roden, E.E. and J.H. Tuttle. 1988. Regional variation of sulfur cycling in Chesapeake Bay sediments.  American Geophysical Union Ocean Sciences Meeting, February 1988.

Roden, E.E. and J.H. Tuttle. 1987. Microbial sulfate reduction and carbon flow in mesohaline Chesapeake Bay sediments.  Annual Meeting of the American Society for Microbiology, May 1987.

GUEST LECTURES AT ACADEMIC/RESEARCH INSTITUTIONS:

“Linking microbial ecophysiology and phylogenetics: a case study on biogeochemical redox cycling of iron and nitrogen in anoxic sediments”, The University of Alabama, Department of Biological Sciences, October, 2003.

“Microbial nitrate-dependent oxidation of solid-phase Fe(II)”, Argonne National Laboratory, Division of Environmental Research, August 2003.

“Experimental and modeling analysis of Fe redox cycling kinetics and the influence of microbial Fe(III) oxide reduction on methane production in freshwater wetland sediments”, Auburn University, Department Civil Engineering, September 2002.

“Experimental and modeling analysis of Fe redox cycling kinetics and the influence of microbial Fe(III) oxide reduction on methane production in freshwater wetland sediments”, University of Florida, Department of Soil and Water Science, September 2002.

“Microbiological and geochemical controls on bacterial Fe(III) oxide reduction: links between surface chemistry and microbial ecophysiology”, Argonne National Laboratory, Division of Environmental Research, July 2002.

“Immobilization of strontium during iron biomineralization coupled to dissimilatory Fe(III) oxide reduction”, Idaho National Environmental Engineering Laboratory, April 2002.

“Microbiological and geochemical controls on bacterial Fe(III) oxide reduction: links between surface chemistry and microbial ecophysiology”, Department of Biological Sciences, University of Montana, April 2002.

“Mineral breathing microbes: bacterial Fe(III) oxide reduction in ancient and modern sedimentary environments”.  Auburn University, Department of Geology, September 2001.

“Microbiological and geochemical controls on bacterial Fe(III) oxide reduction: links between surface chemistry and microbial (eco)physiology”, Stanford University, Department of Geological and Environmental Sciences, April 2001.

“Microbiological and geochemical controls on bacterial Fe(III) oxide reduction: links between surface chemistry and microbial (eco)physiology”, University of New Mexico, Departments of Biology  and Earth and Planetary Sciences, April 2001.

“Relief for wetland gas production: interactions between Fe(III) oxide reduction and methanogenesis in freshwater wetland sediments”, Southern Illinois University, Department of Microbiology, November 2000.

“Mineral breathing microbes: bacterial Fe(III) oxide reduction in ancient and modern sedimentary environments”.  Summer Research Colloquium Program, Dauphin Island Sea Lab, June 2000.

“Microbial and geochemical controls on bacterial Fe(III) oxide reduction: links between surface chemistry and microbial physiology”.  University of Odense, Denmark, Danish Earth Sciences Center, June 2000.

“Microbial and geochemical controls on bacterial Fe(III) oxide reduction: links between surface chemistry and microbial physiology”.  University of Idaho, Department of Microbiology and Molecular Biology, April 2000.

“Relief for wetland gas production: interactions between Fe(III) oxide reduction and methanogenesis in freshwater wetland sediments”, Mississippi State University, Department of Biology, February 1999.

“Dynamics of Fe cycling in freshwater aquatic sediments: oxidative vs. reductive kinetics”, UFZ Centre for Environmental Research, Department of Inland Water Research Magdeburg, Magdeburg, Germany, June 1998.

“Competitive interactions between Fe(III) oxide reduction and methanogenesis in freshwater wetland sediments”, University of Alabama at Birmingham, Department of Biology, May 1998.

“Microbial and geochemical controls on dissimilatory Fe(III) oxide reduction”, University of Wyoming, Department of Geosciences, April 1998.

“Dynamics of Fe cycling in freshwater aquatic sediments: oxidative vs. reductive kinetics”, Skidaway Institute of Oceanography, February 1998.

“Dynamics of Fe cycling in freshwater aquatic sediments: oxidative vs. reductive kinetics”, Georgia Institute of Technology, School of Earth and Atmospheric Sciences, February 1998.

“Relief for wetland gas production: iron oxide suppression of methane production in freshwater wetland sediments”, Lebanon Valley College, Department of Biology, March 1997.

“Relative influence of direct microbial Fe(III) oxide reduction vs. Fe-S mineral formation on phosphate mobilization in anaerobic sediments”, Allegheny College, Departments of Biology and Environmental Sciences, October 1995.

“Phosphate mobilization in anaerobic wetland sediments: microbial Fe(III) oxide reduction vs. Fe-S mineral formation”, University of Mississippi, Department of Biology, October 1995.

“Microbial Fe(III) oxide reduction in anaerobic sediments and culture”, Tulane University, Department of Ecology, Evolution and Organismal Biology, March 1995.

“Microbial Fe(III) oxide reduction: controls and environmental significance. The University of Alabama, Department of Biological Sciences, February, 1995.

“Microbial Fe(III) oxide reduction in anaerobic sediments and culture”, Dauphin Island Sea Laboratory, April 1994.

“Sulfur cycling in Chesapeake Bay sediments”, Lamar University, Department of Biology, February 1994.

“Sulfur cycling in Chesapeake Bay sediments”, Florida State University, Department of Oceanography, November 1993.

Research Scientists/Postdocs

Stephanie Napieralski

Graduate Students

Lisa Haas, M.S.

Thais Altenberg, M.S.

Marissa Cartwright, M.S.

View a summary of Eric’s Research Funding (Excel)

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Overview

I have a broad range of research and teaching interests in the biogeochemistry and geomicrobiology of soil and sedimentary environments. These interests are interdisciplinary in nature, integrating the fields of low-temperature aqueous geochemistry, microbial ecology and physiology, sediment chemical diagenesis, and ecosystem science. My specific area of expertise is microbial processes in hydromorphic soils and surface/subsurface sediments, and the influence of these processes on the fate of various types of inorganic and organic materials (both natural and contaminant) in sedimentary environments. Much of my work in recent years has been focused on process-level, experimental studies (including the use of pure culture model systems) of the kinetics and mechanistic controls on biogeochemical and geomicrobiological processes in soils and sediments. However, I have a long standing interest in field research dating back to my doctoral work on sulfur biogeochemistry in Chesapeake Bay sediments, and I am currently involved in several major field projects, including a NSF/EPA project on Hg biogeochemistry in Alabama rivers, and two DOE-funded projects pertaining to bacterial metal reduction and biomineralization in shallow subsurface sediments. I also have considerable experience and a burgeoning interest in numerical modeling of biogeochemical processes in surface and subsurface sediments.

Subsurface Biogeochemistry

An important theme of my current research revolves around several DOE (EMSP and NABIR programs) sponsored projects (see the research funding history attached to my list of publications, and the description of these research projects on my web-site) focused on process-level studies of bacterial Fe(III) oxide reduction and Fe redox cycling in relation to trace/contaminant metal biogeochemistry in subsurface sediments. These projects include studies of fundamental geochemical and microbiological controls on Fe(III) oxide reduction; the potential for immobilization of trace metals in carbonate minerals formed during bacterial Fe(III) oxide reduction; the interaction between nitrate and Fe(III) oxide reduction in anaerobic sediments, with specific focus on nitrate-dependent oxidation of solid-phase biogenic Fe(II) compounds; and the dynamics of uranium(VI) in Fe(III) oxide-reducing subsurface sediments. Most of these projects are laboratory-based and directed toward evaluating the potential controls on natural (intrinsic) and accelerated subsurface metal-radionuclide bioremediation. One field-based project is examining the heterogeneity of microbial Fe(III) oxide reduction potential in shallow subsurface sediments in relation to geochemical and geophysical properties. I am also a co-PI on a new DOE-NABIR Field Research Center project examining the potential for in situ immobilization of uranium in fractured subsurface sediments at Oak Ridge National Laboratory in Tennessee. This project provides a vehicle for applying the results of our ongoing mechanistic laboratory research to understanding the dynamics of Fe(III) oxide reduction and associated biogeochemical processes in a real subsurface sedimentary environment.

Other Biogeochemistry Projects

I have conducted (in collaboration with R.G. Wetzel, now at UNC Chapel Hill) a NSF project on organic carbon metabolism in freshwater wetland sediments, and the role of microbial Fe(III) oxide reduction in regulation of methane production and emission to the atmosphere. This is an ongoing project (now funded indirectly through research overhead) which has recently led to the discovery that dissimilatory metal-reducing bacteria (DMRB) can transfer electrons to solid-phase humic substances in soils and sediments. Although the ability of DMRB to reduce soluble humic substances and thereby promote (via electron shuttling mechanisms) the reduction of oxidized metals is well-recognized, our findings represent the first demonstration that solid-phase humics can be enzymatically reduced by bacteria. These findings have important implications for sediment biogeochemistry because solid-phase humics are generally 100 to 1000-fold more abundant (on a bulk sediment basis) than dissolved humics in sediment pore fluids. Our findings indicate that reduction of solid-phase humics has the potential to both accelerate the reduction of oxidized metals (e.g. Fe(III) oxides) as well as influence overall electron balance in organic-rich sediments.

I was a co-PI on a recently completed (June 2003) interdisciplinary NSF/EPA Water and Watersheds project examining the biogeochemistry of mercury in riverine ecosystems in Alabama, for which my laboratory was in charge of sediment biogeochemical characterization and microbial mercury transformation measurements. This work on sediment Hg biogeochemistry has led to participation (as Co-PI) in NSF Biocomplexity (Coupled Biogeochemical Cycles) and Ecosystem Studies proposals, both headed-up by Cindy Gilmour of the Philadelphia Academy of Natural Sciences, to examine mechanisms of net microbial methyl-mercury production in the Experimental Lakes Area in northwest Ontario. These projects are designed to complement the joint U.S./Canadian METAALICUS project, whose goal is explore the connection between atmospheric Hg loading and Hg biogeochemistry and trophodynamics in northern lake ecosystems. Finally, I have conducted studies of the controls on phosphorus mobility in anaerobic sediments, and more recently of aerobic bacterial Fe(II) oxidation and the potential for microscale microbial Fe cycling at redox interfaces (see further descriptions below), both with support from The School of Mines and Energy Development at The University of Alabama.

Fe Biomineralization

I am currently collaborating with several interfacial geochemistry colleagues (e.g. at the Environmental Molecular Sciences Laboratory at PNNL; note collaboration with Y. Gorby on DOE-EMSP U(VI) reductive immobilization project) on developing a more detailed understanding of how dissimilatory metal oxide-reducing microorganisms influence the mineralogy and surface chemical properties of Fe(III) oxide-bearing soils and sedimentary materials, through application of high resolution TEM with lattice-fringe imaging, Mössbauer spectroscopy, and X-ray spectroscopy/microscopy. Of particular interest is the physical and chemical nature of Fe(II)-bearing surface phases formed during bacterial Fe(III) oxide reduction, their metal sorption properties relative to unreduced oxide surfaces, and the potential for such phases to incorporate and immobilize contaminant metals. This is currently a subject of intense interest within the subsurface biogeochemistry community given the profound influence such modifications may have on the fate and transport of metals and radionuclides in the subsurface. I am working with Ravi Kukkadapu and John Zachara at PNNL/EMSL on analysis of Fe(III) oxide mineralogy and bacterial reduction end-products in the coastal plain aquifer sediments which we have been studying through the DOE-NABIR project on the heterogeneity of bacterial Fe(III) oxide reduction potential in subsurface sediments, and such collaborations will be extended through the new NABIR FRC project on which Zachara is a co-PI. In addition, I anticipate development of collaborations with Ken Kemner at Argonne National Laboratory on XAS analysis of Fe, S, and U-bearing minerals generated during experimental studies of the interaction between bacterial Fe(III) oxide reduction, bacterial sulfate reduction, and biotic/abiotic U(VI) reduction in subsurface sediments.

Paleo/Astrobiology: Fe-based microbial life systems

A new area of research, which evolved out of our recent studies on bacterial Fe(II) oxidation and microbial Fe cycling, involves studies of microbially-catalyzed Fe redox cycling in layered microbial communities, with specific goal of studying of natural and experimental systems as analogs to possible Fe-based microbial life on ancient Earth and Mars (note current participation in NASA Astrobiology project led by Jill Banfield at U.C. Berkeley). Such studies include the application of molecular techniques (fluorescence in situ hybridization with 16S rRNA probes) for tracking Fe(III)-reducing and Fe(II)-oxidizing bacteria in mixed culture, utilization of novel voltammetric microsensors for determination of dissolved Fe(II) concentrations at submillimeter resolution (collaboration with G. Luther at the University of Delaware), and determination of Fe stable isotope fractionation during bacterial Fe redox transformations. I participated this spring in the submission of major proposal to the NASA Astrobiology Institute program to develop a virtual research institute focused on Fe- and S-based microbial systems, and we recently received word that this project (entitled Biospheres of Mars: Ancient and Recent Studies) has been selected for funding. In addition, I was a co-PI (with B. Beard and C. Johnson at University of Wisconsin, and S. Benner at Desert Research Institute) on a recent (December 2002) NSF Biogeosciences proposal submission entitled “Biotic and Abiotic Controls on Iron Isotopic Geobiological Signatures in Authigenic Magnetite and Siderite”, which seeks a comprehensive analysis of Fe isotope fractionation during bacterial Fe(III) oxide reductive dissolution and associated Fe biomineralization. This project involves extensive experimental studies, which will be extended through measurement of the Fe isotopic composition of Fe(II)-bearing minerals and (when possible) dissolved Fe(II) in sediment pore fluids in natural Fe(III) oxide-reducing environments, including modern sediments and materials from the rock record in which reductive transformations have produced reduced Fe mineral phases. The fundamental goal of the proposed research is to advance the use of Fe isotopes as a biosignature and as a paleoenvironmental indicator of ancient environments.

Aquatic Ecosystem Science

I recently led a major collaborative effort (with scientists at UA, University of New Mexico, University of Florida, University of Vermont, and the South Florida Water Management District) to develop a project in the new NSF Frontiers in Integrative Biological Research program, which would examine the role of biogeochemical cycling and microbial-detrital food web function in the restoration of the Kissimmee River ecosystem in Florida. The Kissimmee River Restoration represents the largest river ecosystem restoration effort ever attempted, and provides a compelling venue for studying how hydro-biogeochemical processes and their linkage with detrital organic matter and nutrient processing influence aquatic ecosystem restoration. The interdisciplinary research would include monitoring and modeling of hydrological fluxes and their impact on biogeochemical processes in restored vs. impacted zones; molecular genetic analysis of microbial community structure/diversity across spatial and temporal gradients in relation to biogeochemical fluxes and the function of the microbial/detrital food web; and linked hydrological and spatially-explicit systems dynamics modeling of ecosystem function. Although the planning proposal submitted in November 2002 was not selected for funding, my engagement in this project was significant in that it stimulated my long-standing interest in ecosystem science, specifically in relation to the often-neglected role of biogeochemical processes in ecological restoration.

Molecular Microbial Ecology

Embedded in all of the studies described above is the goal of relating the spatial-temporal distribution of key functional groups of microorganisms to observed physiochemical properties and patterns of biogeochemical flux. Recently introduced molecular biological approaches for analysis of microbial communities in natural (and engineered) environments will be applied to achieve this goal. These techniques offer an unprecedented opportunity for rapid and accurate assessment of bacterial communities in virtually all types of environmental (as well as clinical) materials, and for testing hypotheses related to the role which microorganisms (e.g. ones with highly specialized metabolic capabilities) may play in controlling biogeochemical fluxes at environmental interfaces. Such studies initially revolve around the use of 16S rRNA/rDNA, but will eventually include analysis of the expression of specific genes involved in relevant microbial metabolic processes. We have recently used 16S rDNA techniques for analysis of aerobic bacterial diversity and community succession in freshwater wetland biofilms (Jackson et al., 1998; Jackson et al., 2000a; Jackson et al., 2000b), and are currently employing this approach for analysis of sediments undergoing redox shifts between nitrate-reducing, Fe(III)-reducing, and nitrate-dependent Fe(II)-oxidizing conditions (Weber et al., 2002). During a sabbatical leave last spring at Pacific Northwest National Laboratory, I pursued the development of microarray techniques for examination of the diversity and abundance metal-reducing bacterial communities in soil and sedimentary environments. The expertise gained during this sabbatical leave will be expanded through the new field-based subsurface metal reduction project described above. These and other molecular techniques (as well as traditional culture-based methods) will be used in all aspects of my ongoing research program in aquatic biogeochemistry.

Biogeochemical Modeling

Mathematical models provide an important quantitative (and ultimately, predictive) link between field and laboratory studies of chemical cycling and mass flux in aquatic systems. Beginning with my dissertation work on estuarine sediment biogeochemistry, I have directed substantial energy toward development of transport-reaction models of biogeochemical processes in sedimentary environments. I have worked extensively with one-dimensional transport-reaction modeling of aquatic sediments, and am well-accustomed to thinking about how physical transport and microbial metabolic processes interact to control the fate of various kinds of materials in environmental systems. Thus, I am capable of speaking the language of modeling professionals in the geosciences and engineering, and I consider this to be one of my strongest interdisciplinary talents.

Examples of my research which combine modeling with laboratory and/or field studies include: dissolved sulfide diagenesis in estuarine sediments (Roden and Tuttle, 1992); sulfate reduction and S recycling in low-salinity estuarine sediments (Roden and Tuttle, 1993); seasonal patterns of organic carbon metabolism in estuarine sediments, and particulate/dissolved organic carbon diagenesis in relation to decay kinetics and particle/solute transport (Roden and Tuttle, 1996); Fe diagenesis (redox cycling) in freshwater wetland sediments (Roden, 2002); nitrate-dependent ferrous iron oxidation (Weber et al., 2001); and kinetic and equilibrium speciation modeling of controls on microbial Fe(III) oxide reduction (Roden and Urrutia, 1999; Urrutia et al., 1999). I have also developed provisional simulations of parallel Fe(III) oxide and U(VI) reduction in subsurface sediments; subsurface microbial redox zonation and arsenic fate and transport, and sediment organic matter diagenesis/redox zonation and Hg speciation. Each of the latter models were created as contributions to federal (DOE and NSF) research proposals. A listing of VBA code as applied to simulation of parallel Fe(III) oxide and U(VI) reduction in a single Representative Elementary Volume (REV) of subsurface sediment is available on my web site.

I am currently working with a computer science graduate student on development of a biogeochemical modeling software package which employs Excel for data storage and graphical analysis, VBA for graphical user interfacing, and library of compiled Fortran programs for numerical computation. Once completed, the software will be supplemented with a user’s manual and made available to a variety of microbiological, geochemical, biogeochemical, and environmental engineering colleagues. In addition, the package will eventually be partnered with a textbook on biogeochemical modeling which I plan to produce within the next 3-5 years. I anticipate that these products will be of substantial use to biogeoscience researchers and students in need of a convenient, easy-to-use, and inexpensive simulation modeling environment.

Through collaboration with William Burgos at Penn State University and Carl Steefel at Lawrence Livermore National Laboratory, I have recently become involved in the use of more sophisticated reactive transport models (e.g. George Yeh’s HYDROBIOGEOCHEM; Steefel’s OS3D/GIRMT/CRUNCH) of geochemical and microbiological processes associated with metal-radionuclide contaminant fate and transport in subsurface environments. For example, I recently participated a DOE-NABIR sponsored workshop on the use of the BIOGEOCHEM module of Yeh’s HYDROBIOGEOCHEM code, and have interacted several times with Steefel en route to setting-up provisional simulations of subsurface microbial redox zonation. The next step in application of these advanced codes will be toward simulation of laboratory studies of coupled microbial-geochemical processes in anaerobic sediments, including reactive transport studies with experimental columns for which we are currently funded, as well as future experimental manipulation studies with intact subsurface core segments. Ultimately, one or more of these codes will be used in conjunction with field-scale remediation projects, e.g. the new NABIR FRC project on coupled Fe/U reductive biomineralization at ORNL.

Teaching

The focus of my teaching at The University of Alabama has been on the role of microbial processes in biogeochemical cycling and material flux at various levels of organization, including cell-molecular, population-community, and ecosystem-global scales. I have developed an interdisciplinary instructional program consisting of the following four courses: (1) an upper division/graduate lecture course in microbial ecology; (2) an upper division/graduate microbial ecology-biogeochemistry laboratory course, which includes use of molecular techniques for bacterial detection/quantification and community analysis; (3) an upper division/graduate lecture plus computer laboratory course in environmental modeling; and (4) a graduate lecture course in aquatic biogeochemistry. This curriculum is designed to support my research program in microbial ecology and biogeochemistry, and is thus reflective of my general philosophy that an effective advanced undergraduate/graduate-level teaching program should interface as directly as possible with (and be supported intellectually by) an effective research program. I have also coordinated (in collaboration with W.B. Lyons, formerly in the Department of Geology at UA) a graduate seminar course in trace metal biogeochemistry, and participated in a team-taught graduate course in Geomicrobiology offered through a current NSF-IGERT project collaboration with the University of New Mexico. In addition, I have on two occasions taught a 2-week minicourse on ecological modeling in an advanced ecology course offered at UA. Finally, I have recently participated in the development of interdisciplinary, inquiry-based undergraduate course entitled Introduction to Inquiry, which has been supported through grants from the NSF-ILI program, and the Howard Hughes Medical Institute. The goal of the course is to train students in hypothesis-driven research approaches, and to provide them with hand-on experience in state-of-the art molecular biological and experimental ecological techniques.

The advanced undergraduate/graduate curriculum described above could be readily adapted to fit the needs of an environmental science/engineering or geoscience program. For example, various components of the above courses could be folded into a one-semester advanced undergraduate/graduate course in biogeochemical cycling, which would be followed-up by graduate-level courses in geomicrobiology and biogeochemical modeling. The biogeochemical modeling course would emphasize fundamental concepts required to simulate coupled microbial-geochemical processes in natural environments. The Visual Basic, Matlab, and/or Fortran programs which I have developed for research applications are of substantial value for this purpose; other problems taken from texts on environmental [e.g. Brezonik (1994), Schnoor (1996)] and geochemical [e.g. Walker (1991)] and modeling have also been implemented. A salient aspect of my teaching philosophy is that all environmental science/engineering and geoscience students who intend to work on biogeochemical cycling problems need to receive specific training in how to incorporate microbially-catalyzed processes into standard (kinetic plus equilibrium) reaction frameworks for holistic simulation of biogeochemical processes in natural environments.

References

Brezonik, P.L. 1994. Chemical kinetics and process dynamics in aquatic systems, Lewis Publishers.
Jackson, C.R., E.E. Roden, and P.F. Churchill. 1998. Changes in bacterial species composition in enrichment cultures with varying inoculum dilution as monitored by denaturing gradient gel electrophoresis. Appl. Environ. Microbiol. 98:5046-5048.
Jackson, C.R., P.F. Churchill, and E.E. Roden. 2000a. Successional changes in bacterial assemblage structure during epilithic biofilm development. Ecology 82:555-566.
Jackson, C.R., E.E. Roden, and P.F. Churchill. 2000b. Denaturing gradient gel electrophoresis can fail to separate 16S rDNA fragments with multiple base differences. Mol. Biol. Today 1:49-51.
Roden, E.E. 2002. Modeling iron redox cycling and the influence of microbial Fe(III) oxide reduction on methanogenesis in freshwater wetland sediments. Manuscript in preparation.
Roden, E.E., and J.H. Tuttle. 1992. Sulfide release from estuarine sediments underlying anoxic bottom water. Limnol. Oceanogr. 37:725-738.
Roden, E.E., and J.H. Tuttle. 1993. Inorganic sulfur turnover in oligohaline estuarine sediments. Biogeochemistry 22:81-105.
Roden, E.E., and J.H. Tuttle. 1996. Carbon cycling in mesohaline Chesapeake Bay sediments 2: kinetics of particulate and dissolved organic carbon turnover. J. Mar. Sci. 54:343-383.
Roden, E.E., and M.M. Urrutia. 1999. Ferrous iron removal promotes microbial reduction of crystalline iron(III) oxides. Environ. Sci. Technol. 33:1847-1853.
Schnoor, J.L. 1996. Environmental modeling, Wiley Interscience.
Urrutia, M.M., E.E. Roden, and J.M. Zachara. 1999. Influence of aqueous and solid-phase Fe(II) complexants on microbial reduction of crystalline Fe(III) oxides. Environ. Sci. Technol. 33:4022-4028.
Walker, J.C.G. 1991. Numerical adventures with geochemical cycles, Oxford University Press.
Weber, K.A., F.W. Picardal, and E.E. Roden. 2001. Microbially-catalyzed nitrate-dependent oxidation of biogenic solid-phase Fe(II) compounds. Environ. Sci. Technol. 35:1644-1650.
Weber, K.A., P.F. Churchill, and E.E. Roden. 2002. Microbial community structure associated with interaction between nitrogen and iron redox cycles in freshwater sediments. Manuscript in preparation.

Reviewing:

• Member, Editorial Board, Microbial Ecology
• Ad hoc reviewer for:

Applied and Environmental Microbiology
Archiv für Hydrobiologie
Biogeochemistry
Chemical Geology
Chemosphere
Environmental Science & Technology
Estuaries
FEMS Microbiology Ecology
Geochimica Cosmochimica Acta
Limnology and Oceanography
Water, Air, and Soil Pollution
Water Research

Editorial:

Co-Guest (with Yuri A. Gorby, Pacific Northwest National Laboratory) editor for Geomicrobiology Journal Special Issue on Microbial Fe(III) Oxide Reduction, April 2002. Contributors: (1) W.D. Burgos, R.A. Royer, G.T. Yeh, Y.L. Fang, A.S. Fisher, B.H. Jeon, B.A. Dempsey; (2) F. Caccavo and A. Das; (3) K.P. Nevin and D.R. Lovley; (4) E.E. Roden and M.M. Urrutia; (5) J.M. Zachara, R.K. Kakadapu, J.K. Fredrickson, Y.A. Gorby, S.C. Smith.

Roden Geomicrobiology Laboratory

I occupy a 1800 square foot laboratory in a new wing of Weeks Hall that houses the Department of Geology and Geophysics at UW-Madison. The laboratory is specifically equipped for handling anaerobic materials and microorganisms, in particular the culturing and manipulation of anaerobic respiratory and lithotrophic bacteria. The new laboratory also includes a molecular biological facility for nucleic acid extraction (from cultures or soil/sediment samples) and manipulation en route to sequencing and/or quantitative PCR analysis. Through ongoing DOE-funded (EMSP and NABIR programs; see Research Projects) research, a sediment core reactor facility for conducing reactive transport experiments with repacked and intact subsurface sediment cores has been developed. A diverse array of column reactors and associated pumping systems are available to support reactive transport studies involving microbial metabolism.

Major pieces of equipment available in my laboratory are as follows:

• Autoclave (Primus)
• Lyophilizer (Fisher Scientific)
• Analytical balances (Denver Instruments)
• UV/VIS spectrophotometer (Shimadzu)
• Gas chromatograph with FID and TCD detectors (Shimadzu)
• High-pressure liquid chromatograph with UV/VIS and RI detectors (Shimadzu)
• Ion chromatograph (Dionex DX-100)
• BET Surface area analyzer (Micromeritics)
• Anaerobic chambers (Coy and Labconco)
• High speed centrifuge (Sorvall RC5)
• Microcentrifuges (Fisher)
• Thermal cycler (BioRad/MJ DNA Engine)
• Gel documentation system (Biorad)
• DGGE system (BioRad D-Code)
• Real-time PCR detector (BioRad/MJ Chromo 4)
• Compound phase contrast/epifluorescence microscope (Nikon E600)
• Temperature-regulated incubators

Xu Huifang Mineralogy/Nanogeoscience Laboratory

Xu occupies a laboratory adjacent to Roden in the new wing of the Geology and Geophysics. This laboratory is equipped for a variety of microscopic and spectroscopic mineralogical analyses, including:

• X-ray diffraction (XRD): A Sintag Pad V automated powder XRD unit with Jade (Materials Data, Inc.) and Shaddow software for data reduction and analysis.
• Microporosimeter: a new Micromeritics ASAP 2020 porosimeter that can measure BET surface area, nanopore surface area, and nanopore sizes will be installed in spring of 2005.
• Atomic absorption spectrometer (AA): A Perkin-Elmer 5100PC atomic absorption spectrophotometer will be used for the concentration of metal ions in solutions.
• Surface analysis system: A VCA Optima Surface Analysis System from AST Products that can measure static and dynamic contact angle and surface energy will be installed in laboratory in Spring of 2005.
• Optical microscope: Olympus BX51

Instruments at the Materials Science Center

Transmission Electron Microscopes:

• 200 kV high-resolution Phillips CM200 Ultratwin TEM with 0.19 nm point-to-point resolution, Ge light element energy-dispersive X-ray spectroscopy (EDS) system, Gatan multi-scan CCD (charge-coupled device) camera, and full processing and analysis capabilities. NORAN Voyager 127 eV Be thin window EDS
• A 120 kV energy-filtered TEM (LEO EM 912) with integrated omega filter that provides TEM imaging, electron energy-filtering TEM imaging, and electron diffraction from nanometer scale areas.
• Vacuum Generators HB-501 ultra-high vacuum, field-emission gun STEM (for Z-contrast imaging) with light element EDS and parallel electron energy loss spectroscopy (PEELS)

Scanning Electron Microscopes

• A fully digital LEO GEMINI 1530 SEM with field emission electron gun, full orientation imaging based on backscattered electron Kikuchi patterns, and full EDS and control
• A JSM-6100 is a modern Scanning Electron Microscope (SEM) that uses a tungsten thermionic electron source. It is an excellent general purpose SEM. The SEM is equipped with an onboard image averaging and acquisition system that greatly improves operation under difficult imaging conditions. In addition, there is a PC based active image acquisition system that allows the capture, processing, and electronic storage of high-resolution images. Other accessories include a Backscattered Electron Detector (BSE), and a full-featured PC based X-ray Energy-dispersive Analysis System (EDS).
• A NORAN Instruments ADEM 30kV SEM with light element EDS and sophisticated image processing and feature analysis capabilities. The instrument has a 6-axis stage that can handle unusually large samples up to 8-inch diameter.
• Focused Ion Beam (FIB): A newly installed Zeiss 1540 XBeam FESEM/FIB with in-lens secondary and backscattered detectors, gas injectors for deposition and etching, and micromanipulators for TEM sample lift-out.
• XRD: Stoe X-ray diffractometer. The Stoe Instrument is a High Resolution X-ray Diffractometer. 2-theta range: 0.15 degrees to 140 degrees.
• PANalytical X’Pert PRO MRD system: (high-resolution X-ray diffraction) can be configured with a hybrid monochromator or a high-resolution monochromator to fulfill high-resolution X-ray diffraction requirements. With PANalytical’s X’Pert PRO Extended MRD system, an X-ray mirror and a high-resolution monochromator can be placed in line to deliver an incident X-ray beam that is not only highly monochromatic with a low divergence, but also has a high intensity. This high intensity is used to uncover the weakest details in a diffraction experiment. X’Pert Epitaxy and Smoothfit provides functionality to analyze rocking curves, reciprocal space maps and wafer maps. Rocking curves can be simulated and fitted using patented algorithms

Other instrumentation in geology & geophysics

MC-ICP-MS: The GV Instruments IsoProbe installed at UW-Madison is a next-generation multi-collector inductively-coupled plasma mass spectrometer (MC-ICP-MS) that was installed in 2000. The IsoProbe is capable of very high-precision isotopic analysis and trace metal analysis of a variety of geologically important elements including Li, B, Mg, S, Cl, Ca, Cr, Fe, Ni, Cu, Zn, Se, Sr, Nd, Hf, Os, Hg, Pb, Th, and U.

Microprobe: A Cameca SX-50/51 electron microprobe that was installed in 1993 is capable in-situ chemical composition, X-ray maps from micro-scale areas, back-scattering imaging, and X-ray EDS analysis and mapping. The lab is managed by a full-time 100% university-supported research scientist, Dr. John Fournelle.

Ion probe: A new multicollector Cameca large radius ion microprobe (funded by NSF) was installed in the Department of Geology and Geophysics, UW-Madison in early 2005 as a national facility for stable isotope studies (WiscSIMS). The ion probe can also provide spatial-resolved trace element analysis. The lab is managed by a full-time research scientist, Dr. Noriko Kita.

Thin section shop: A ¾-time thin section preparatory, Brian Hess, maintains a complete facility in the department for variety of thin and polished sections.

Machine shop: A well-equipped shop is managed by a half-time machinist, Lee Putman, who has made components used in many designed instruments in the department.

Electronics shop: Located in the department, used primary for geological instrumentation, development and repair. It is staffed by full-time electronics engineers Lee Powell and Neal Lord.

Instrumentation available in the Environmental Chemistry and Technology Program:

• Inductively Coupled Plasma Optical Emission
• Spectrometer (PE Optima 4300 DV)
• Electrophoresis system (PenKem 3000)
• Particle counter/sizers (Brinkman time of transition analyzer and Brookhaven BI-2030-AT)
• Inductively Coupled Plasma Mass Spectrometer (VG PlasmaQuad II+)
• Voltammetry System (Radiometer Trace Lab 50 /HDME/SMDE/DME and 6mm RDE)
• High Performance Liquid Chromatography System (Waters 600 with 991 diode array); Fourier Transform Infrared Spectrometer (Nicolet 60SX with 680DSP)
• Carbon analyzers (Shimadzu TOC-5000 with SSM)
• Trace Sulfur analyzer (APS instruments)

Instrumentation available in the Environmental Chemistry & Technology program

• Inductively Coupled Plasma Optical Emission Spectrometer (PE Optima 4300 DV)
• Electrophoresis system (PenKem 3000)
• Particle counter/sizers (Brinkman time of transition analyzer and Brookhaven BI-2030-AT)
• Inductively Coupled Plasma Mass Spectrometer (VG PlasmaQuad II+)
• Voltammetry System (Radiometer Trace Lab 50 /HDME/SMDE/DME and 6mm RDE)
• High Performance Liquid Chromatography System (Waters 600 with 991 diode array); Fourier Transform Infrared Spectrometer (Nicolet 60SX with 680DSP)
• Carbon analyzers (Shimadzu TOC-5000 with SSM)
• Trace Sulfur analyzer (APS instruments)

Regulation of methane flux from freshwater wetland sediments by competing anaerobic microbial processes (NSF)