Staff

Thomas Hofstetter

PD Dr. Thomas Hofstetter

Senior Scientist

Department Environmental Chemistry

About Me

Thomas B. Hofstetter is a senior scientist at Eawag's Department of Environmental Chemistry and leads the Environmental Chemistry Stable Isotope Lab. His primary interest is to understand how degradation and formation reactions organic pollutants work.


Even in Environmental Chemistry "little things can make a big difference". Our preferred level of study is therefore the molecular scale. The know-how obtained from talking to molecules, atoms, and a few sub-atomic particles enables us assess quantitatively the numerous processes that ultimately determine the fate of organic pollutants behave in aquatic environments. Thomas Hofstetter and his research group apply a variety of approaches to achieve their research goals.

  1. We study of reaction mechanisms in (laboratory) model systems for enzyme- and mineral-catalyzed redox reactions, water disinfection processes, and photochemical transformations.
  2. With compound-specific stable isotope analysis, we have an excellent tool at hand for studying (bio)chemical reactions. Tiny variations of isotope ratios found at natural isotopic abundances reveal, on the one hand, the origin of an element or molecule. On the other hand, the systematic variation of isotope ratios reflect isotope effects of chemical reactions and physical processes and are, therefore powerful proxies for reactive processes on very different time scales.
  3. Finally, we aim at understanding the biogeochemical context, in which reactions of organic and inorganic pollutants happen. To this end, we study the redox properties of iron-bearing minerals, specifically, phyllosilicates and iron oxides from their availability as terminal electron acceptors to the quantification of fundamental redox parameters.
None of these goals would be achieved without the fruitful collaboration with and advice from numerous colleagues and friends of good (environmental and chemical) sciences.

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Projects

N-nitrosamines such as N-nitrosodimethylamine (NDMA) are of public and regulatory concern because these potent carcinogens can be formed as unintented by-products during drinking and waste water disinfection/oxidation.
Nitroaromatic explosives persist in the subsurface in different phases (e.g., bound to soil or sediment matrix or as solid-phase residues) and it is extremely challenging to assess biotic and mineral-catalyzed degradation. With the combined analysis of C, N, and H isotope fractionation, we can quantify transformation, even if it takes place via several potentially competing pathways over time-scales of decades.
A new approach for the CSIA of aquatic micropollutants in the sub-microgram/liter range

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Curriculum Vitae

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Selected publications

Wijker, R. S.; Pati, S. G.; Zeyer, J.; Hofstetter, T. B. (2015) Enzyme kinetics of different types of flavin-dependent monooxygenases determine the observable contaminant stable isotope fractionation, Environmental Science and Technology Letters, 2(11), 329-334, doi:10.1021/acs.estlett.5b00254, Institutional Repository
Ratti, M.; Canonica, S.; McNeill, K.; Bolotin, J.; Hofstetter, T. B. (2015) Isotope fractionation associated with the indirect photolysis of substituted anilines in aqueous solution, Environmental Science and Technology, 49(21), 12766-12773, doi:10.1021/acs.est.5b03119, Institutional Repository
Ratti, M.; Canonica, S.; McNeill, K.; Bolotin, J.; Hofstetter, T. B. (2015) Isotope fractionation associated with the photochemical dechlorination of chloroanilines, Environmental Science and Technology, 49(16), 9797-9806, doi:10.1021/acs.est.5b02602, Institutional Repository
Ratti, M.; Canonica, S.; McNeill, K.; Erickson, P. R.; Bolotin, J.; Hofstetter, T. B. (2015) Isotope fractionation associated with the direct photolysis of 4-chloroaniline, Environmental Science and Technology, 49(7), 4263-4273, doi:10.1021/es505784a, Institutional Repository
Sander, M.; Hofstetter, T. B.; Gorski, C. A. (2015) Electrochemical analyses of redox-active iron minerals: A review of nonmediated and mediated approaches, Environmental Science and Technology, 49(10), 5862-5878, doi:10.1021/acs.est.5b00006, Institutional Repository
Spahr, S.; Bolotin, J.; Schleucher, J.; Ehlers, I.; von Gunten, U.; Hofstetter, T. B. (2015) Compound-specific carbon, nitrogen, and hydrogen isotope analysis of N-nitrosodimethylamine in aqueous solutions, Analytical Chemistry, 87(5), 2916-2924, doi:10.1021/ac5044169, Institutional Repository
Hofstetter, T. B.; Bolotin, J.; Pati, S. G.; Skarpeli-Liati, M.; Spahr, S.; Wijker, R. S. (2014) Isotope effects as new proxies for organic pollutant transformation, Chimia, 68(11), 788-792, doi:10.2533/chimia.2014.788, Institutional Repository
Gorski, C. A.; Klüpfel, L. E.; Voegelin, A.; Sander, M.; Hofstetter, T. B. (2013) Redox properties of structural Fe in clay minerals: 3. Relationships between smectite redox and structural properties, Environmental Science and Technology, 47(23), 13477-13485, doi:10.1021/es403824x, Institutional Repository
Gorski, C. A.; Klüpfel, L.; Voegelin, A.; Sander, M.; Hofstetter, T. B. (2012) Redox properties of structural Fe in clay minerals. 2. Electrochemical and spectroscopic characterization of electron transfer irreversibility in ferruginous smectite, SWa-1, Environmental Science and Technology, 46(17), 9369-9377, doi:10.1021/es302014u, Institutional Repository
Gorski, C. A.; Aeschbacher, M.; Soltermann, D.; Voegelin, A.; Baeyens, B.; Marques Fernandes, M.; Hofstetter, T. B.; Sander, M. (2012) Redox properties of structural Fe in clay minerals. 1. Electrochemical quantification of electron-donating and -accepting capacities of smectites, Environmental Science and Technology, 46(17), 9360-9368, doi:10.1021/es3020138, Institutional Repository
Schwarzenbach, R. P.; Egli, T.; Hofstetter, T. B.; von Gunten, U.; Wehrli, B. (2010) Global water pollution and human health, Annual Review of Environment and Resources, 35, 109-136, doi:10.1146/annurev-environ-100809-125342, Institutional Repository
Elsner, M.; Jochmann, M. A.; Hofstetter, T. B.; Hunkeler, D.; Bernstein, A.; Schmidt, T. C.; Schimmelmann, A. (2012) Current challenges in compound-specific stable isotope analysis of environmental organic contaminants, Analytical and Bioanalytical Chemistry, 403(9), 2471-2491, doi:10.1007/s00216-011-5683-y, Institutional Repository
Hofstetter, T. B.; Berg, M. (2011) Assessing transformation processes of organic contaminants by compound-specific stable isotope analysis, Trends in Analytical Chemistry, 30(4), 618-627, doi:10.1016/j.trac.2010.10.012, Institutional Repository
Elsner, M.; Hofstetter, T. B. (2011) Current perspectives on the mechanisms of chlorohydrocarbon degradation in subsurface environments: Insight from kinetics, product formation, probe molecules, and isotope fractionation, In: Tratnyek, P. G.; Grundl, T.; Haderlein, S. B. (Eds.), Aquatic Redox Chemistry, 407-439, doi:10.1021/bk-2011-1071.ch019, Institutional Repository
Wijker, R. S.; Bolotin, J.; Nishino, S. F.; Spain, J. C.; Hofstetter, T. B. (2013) Using compound-specific isotope analysis to assess biodegradation of nitroaromatic explosives in the subsurface, Environmental Science and Technology, 47(13), 6872-6883, doi:10.1021/es3051845, Institutional Repository
Pati, S. G.; Kohler, H.-P. E.; Bolotin, J.; Parales, R. E.; Hofstetter, T. B. (2014) Isotope effects of enzymatic dioxygenation of nitrobenzene and 2-nitrotoluene by nitrobenzene dioxygenase, Environmental Science and Technology, 48(18), 10750-10759, doi:10.1021/es5028844, Institutional Repository

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Address

E-Mail: thomas.hofstetter@eawag.ch
Phone: +41 58 765 5076
Fax: +41 58 765 5802
Address: Eawag
Überlandstrasse 133
8600 Dübendorf
Office: BU E13

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