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Environmental Chemistry
Prof. Kristopher McNeill, Chair
Dr. Michael Sander, Senior Group Leader
The Environmental Chemistry group at ETH studies the fate of organic molecules in aquatic systems, focusing on photochemical transformation reactions, emerging contaminants, and the environmental chemistry of biomacromolecules.
Group NewsYou can also follow Kris McNeill on Twitter |
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June 4, 2013Complete hydrodehalogenation of polyhalogenated benzenes using rhodium-based catalystContinuing work by Rebekka Baumgartner with a rhodium on aluminum oxide catalyst under mild aqueous conditions (see news item dated August 29, 2012) demonstrates the degradation of a number of polyfluorinated and polychlorinated benzenes. As reported in a new article in Environ. Sci. Technol., the catalyst enabled full defluorination of all congeners of fluorinated benzenes, making this method potentially viable for the remediation of groundwater contaminated with halogenated benzenes.
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June 3, 2013Covalent binding of a sulfonamide antibiotic to soil organic matterSulfonamide antimicrobials used in veterinary drugs and animal feeds enter agriculture soils via the application of manure and are retained as non-extractable soil residues. Recently published work by Anna Gulkowska in Environ. Sci. Technol. probes the catalytic role of oxidases in the formation of covalent bonds between sulfamethazine and soil organic matter (SOM). This collaborative work from the Sander, Juliane Hollender (Eawag) and Martin Krauss (Helmhotz Center) groups suggests unreactive hydroquinone moieties in SOM can be oxidized to electrophilic quinones, leading to covalent bond formation via nucleophilic addition reactions.
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April 30, 2013Paul's paper honored as one of ES&T's best in 2012Environmental Science & Technology has announced their editors' choices for best papers in 2012. Paul Erickson's paper was among those listed, tied as 1st runner up in the category Best Science Paper. Congratulations, Paul! Below is a link to the paper itself. |
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January 30, 2013Insights into the involvement of radicals in triclosan phototransformationWork
continues in the group probing the phototransformation reactions of
triclosan, a widely used antibacterial agent. A newly published article
in Environ. Sci. Technol. by Sarah Kliegman and Soren Eustis
focuses on the reaction mechanisms of phototransformation, and both
experimental and computational results indicate that a biradical
intermediate is likely the critical intermediate in dioxin, biphenyl,
and phenoxyphenol product formation. |
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January 29, 2013Research finding triclosan in Minnesotan lake sediment in the mediaAs reported in the news item dated October 9, 2012, collaborative work with the Bill Arnold group found increasing triclosan and triclosan-derived dioxin concentrations in lake sediments from Minnesota. A new paper in Environ. Sci. Technol. that covers more Minnesotan lakes has sparked further interest. News about the work is being highlighted in local newspapers across Minnesota, such as the Pioneer Press and Star Tribune, as well as in national syndicates, such as The New York Times and NSF Science360. Quantification of Triclosan, Chlorinated Triclosan Derivatives, and their Dioxin Photoproducts in Lacustrine Sediment Cores |
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October 19, 2012Congratulations to Dr. Britt Peterson!Congratulations to Dr. Britt Peterson, our newest PhD. Britt is the first ETH graduate from Kris McNeill's group, marking the beginning of a new era. Britt's thesis is entitled "Probing natural organic matter photochemistry" and in it she describes her work on NOM fluorescence, production of singlet oxygen by NOM, and reaction of NOM with singlet oxygen. Below is a link to Britt's most recent paper on the production of singlet oxygen in Lake Superior. |
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October 9, 2012Triclosan transformation products highlighted in The State of the River ReportThe recently published State of the River Report describes the current health status of the Mississippi River. Using 13 key indicators, the Report highlights several issues affecting river health, including triclosan, a contaminant of concern. Featured collaborative work by the McNeill and Bill Arnold groups shows that triclosan-derived dioxins have increased by 200 to 300% in sediments from Lake Pepin, a lake in SE Minnesota. |
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September 3, 2012Fate of transgenic proteins in soilsThe Sander group continues its work towards understanding the mechanisms of adsorption of insecticidal Cry proteins from transgenic crop plants to soil particles. New companion papers by Michael Sander and Jeanne Tomaszewski in Environ. Sci. Technol. show the adsorption of a Cry protein (Cry1Ab) to humic substances with different polarities is driven by electrostatic attraction and the hydrophobic effect. The results highlight the importance of including adsorption to soil organic matter in models assessing the fate of Cry proteins in soils. Adsorption of insecticidal Cry1Ab protein to humic substances. 1. Experimental approach and mechanistic aspects |
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August 29, 2012Hydrodefluorination of fluorobenzene using rhodium-based catalystNew work by Rebekka Baumgartner in Environ. Sci. Tech. explores the degradation of fluorobenzene (a high production volume chemical) by a rhodium on aluminum oxide catalyst (Rh/Al2O3) under mild aqueous conditions (1 atm H2, 20oC). Fluorobenzene rapidly degraded (t1/2 ≈ 0.2 h) to form cyclohexane and fluoride, and further mechanistic investigations established a proposed pathway in which rapid hydrodefluorination to benzene is followed by sequential hydrogenation reactions.
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August 24, 2012Measuring redox properties of structural Fe in clay mineralsAs published in companion papers in Environ. Sci. Technol., joint work with Chris Gorski in the Hofstetter lab at Eawag presents the redox properties of structural Fe in clay minerals. The first study elucidates the electron donating and accepting capacities of four natural Fe-bearing clay minerals using a mediated electrochemical technique (see also February 12, 2012 news item). Further investigation in the second study reveals both reversible and irreversible structural Fe re-arrangements upon reduction and re-oxidation cycling. Redox properties of structural Fe in clay minerals: 1. Electrochemical quantification of electron donating and accepting capacities of smectites |
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August 23, 2012Investigating the composition of an aqueous humic substanceRecent studies indicate dissolved organic matter contains a significant fraction of relatively low molecular weight molecules (MW<500 Da), but the composition of this fraction remains unclear. A new study in Environ. Sci. Technol. by Christy Remucal and Rose Cory combined membrane dialysis and high resolution Orbitrap mass spectroscopy to uncover that Suwannee River fulvic acid contains a distinct fraction of low MW components of an aliphatic nature present individually or in loosely bound assemblies. Low Molecular Weight Components in an Aquatic Humic Substance as Characterized by Membrane Dialysis and Orbitrap Mass Spectrometry |
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July 25, 2012Congratulations to Dr. Sarah PageCongratulations to our newest PhD, Sarah Page. Sarah defended her thesis "Hydroxyl radical formation from dissolved organic matter under photochemical and non-photochemical conditions" on the summer solstice (21 June 2012) at the University of Minnesota. She is currently in Alaska wearing full mosquito netting (see picture at right), conducting research on hydroxyl radical production at the Toolik Field Station with George Kling and Rose Cory. |
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July 25, 2012Photochemical production of brominated dioxinsHydroxylated polybrominated diphenyl ethers (OH-PBDEs) are known endocrine disruptors and have been detected in fresh and marine waters as well as aquatic animals. A new study published in Environ. Sci. Technol. by Paul Erickson looks at the photochemical behavior of these compounds and found that the three studied compounds are capable of photochemically generating compounds of concern including brominated dioxins and phenols and a dibenzofuran. |
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June 21, 2012Singlet oxygen production in waters of Lake SuperiorThe results of a multi-year field study on Lake Superior, described in a new paper in Environ. Sci. Technol., unveil correlations of singlet oxygen (1O2) production rates (Rf) and quantum yields (ΦΔ) with characteristics of chromophoric dissolved organic matter (CDOM) in lake water. Using water samples collected from 2005-2009 at nearly 40 sites, Britt Peterson’s work illustrates that Rf is proportional to parameters describing CDOM concentration while ΦΔ is proportional to CDOM composition.
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April 30, 2012Antioxidant properties of humic substances
What is the quantity and what are the identities of the major electron donating groups in humic substances under oxic conditions, like those found in surface waters? New work by Dr. Michael Aeschbacher of the Sander group using a novel electrochemical approach (see also February 12, 2012 news item) shows a variety of moieties can be irreversibly oxidized, but that phenolic moieties are likely the major electron donating groups in humic substances. The paper currently appears as an ASAP article on the Environ. Sci. Technol. website.
Antioxidant Properties of Humic Substances M. Aeschbacher, C. Graf, R.P. Schwarzenbach, and M. Sander, Env. Sci. Technol. 2012, DOI: 10.1021/es300039h |
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April 27, 2012New review article on ROS detection methods
A new compilation of methods for the detection of reactive oxygen species in aqueous environments has just been published online in Aquatic Sciences. The effort was led by Dr. Justina Burns and features work from twelve co-authors.
Methods for reactive oxygen species (ROS) detection in aqueous environments J.M. Burns, W.J. Cooper, J.L. Ferry, D.W. King, B.P. DiMento, K. McNeill, C.J. Miller, W.L. Miller, b.M. Peake, S.A. Rusak, A.L. Rose, T.D. Waite, Aquat. Sci. 2012, DOI: 10.1007/s00027-012-0251-x |
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March 19, 2012Reduced and oxidized humic substances display similar sorption properties
How well do sorption coefficients determined under oxic conditions in the laboratory correspond to those found under reducing conditions, such as in an anoxic aquifer? The work of Dr. Michael Aeschbacher of the Sander group indicates that they correspond well, and one can therefore use the laboratory coefficients to model anoxic systems. The paper appears today on the Environ. Sci. Technol. website.
Assessing the Effect of Humic Acid Redox State on Organic Pollutant Sorption by Combined Electrochemical Reduction and Sorption Experiments M. Aeschbacher, S. H. Brunner, R. P. Schwarzenbach, M. Sander, Env. Sci. Technol. 2012, DOI: 10.1021/es204496d |
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February 12, 2012Sander Group paper among top cited in Env. Sci. Technol.
We have received word that Michael Aeschbacher's 2010 article in Env. Sci. Technol. has broken into the top 20 most cited papers of the last three years. See the entire list here, and follow the link below for the original paper.
Novel Electrochemical Approach to Assess the Redox Properties of Humic Substances M. Aeschbacher, M. Sander, R. P. Schwarzenbach, Env. Sci. Technol. 2010, 44, 87-93. |
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February 9, 2012Isolable Co(I) complex prepared
Elodie Marlier has a new paper in Inorganic Chemistry
describing the successful culmination of a multi-year effort in our
laboratory to prepare a ligand capable of supporting cobalt in the +1
oxidation state. This oxidation state is the key one responsible for the
reactivity of Vitamin B12 toward chlorinated pollutants, and thus relevant to natural microbial remediation and possibly engineered clean-up schemes.
Synthesis and Reactivity of an Isolable Cobalt(I) Complex Containing a β-Diketiminate-Based Acyclic Tetradentate Ligand E.E. Marlier, B.A. Ulrich, K. McNeill Inorg. Chem. 2012, DOI:10.1021/ic201780c |
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January 21, 2012Dark production of hydroxyl radical
Sarah Page has a new paper in Environmental Science & Technology demonstrating that hydroxyl radical is formed upon O2
oxidation of reduced humic acid isolates. The yields are significant,
ranging from 42 to 160 mmol hydroxyl per
mole of electrons. The formation of hydroxyl radical likely involves
hydrogen
peroxide as reaction intermediate. This
reaction has potential importance to biogeochemical cycles and pollutant
dynamics at oxic/anoxic boundaries where organic matter is present. In
fact, the concentrations of hydroxyl radical formed are substantially
higher than what has normally been observed for photochemical production
of hydroxyl radical from humic substances.
Hydroxyl Radical Formation upon Oxidation of Reduced Humic Acids by Oxygen in the Dark S.E. Page, M. Sander, W. A. Arnold, K. McNeill Environ. Sci. Technol. 2012, DOI:10.1021/es203836f |
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October 10, 2011Dr. Michael Aeschbacher!
Congratulations are in order for our newest PhD, Dr. Michael Aeschbacher. Michi successfully defended his thesis entitled "Electrochemical Redox Characterization of Humic Substances", which was supervised by Dr. Michael Sander and Prof. René Schwarzenbach. Here he is pictured enjoying a well-deserved break in the Valais. Congratulations, Michi! |
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