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Environmental Chemistry

Senior Scientific Staff

Prof. Kristopher McNeill, Chair, Environmental photochemistry and reaction mechanisms
Dr. Michael Sander, Redox properties and reactivities of geochemical phases
Prof. Martin Schroth, Subsurface biogeochemistry

Group News

You can also follow Kris McNeill on Twitter

 
Danny_Rachel_Paul


Left to Right: Danny, Rachel, Paul

October 24, 2014

Congratulations to three recent PhDs!

Belated congratulations are in order for three recent PhD students. Paul Erickson defended his PhD (ETH Zurich) On March 14.  Rachel Lundeen defended her PhD (ETH Zurich) on June 12. Danny Sadowsky defended his PhD (Univ. of Minnesota) on August 12.  It marks the end of an era as Danny, Rachel and Paul were the last of Kris McNeill's PhD students who started at the University of Minnesota.  Danny, Rachel and Paul are all working as postdoctoral researchers at EPFL, Univ. of Washington and ETH Zurich, respectively.

TOC_Tony
July 15, 2014

DOM adlayers at the nanoscale: properties and dynamics

Tony published his first Environ. Sci. Technol. paper on the properties and dynamics of dissolved organic matter adlayers on model surfaces. Using a combination of quartz crystal microbalance, ellipsometry, and contact angle measurements, Tony could show that DOM adlayers on positively charged model surfaces are very thin (nm range), relatively rigid, dynamic upon changes in solution ionic strength, and have relatively high surface polarities. Tony further showed how the DOM adlayers can be used to systematically study the interactions of biomacromolecules with DOM.

Dissolved organic matter adsorption to model surfaces: adlayer formation, properties and dynamics at the nanoscale. Armanious, A., Aeppli, M. and M. SanderEnviron Sci Technol, 2014, ja. 10.1021/es5026917

Klupel_Prize
July 15, 2014

Laura awarded SCNAT/SCS 2014 Chemistry Travel Award

The Swiss Academy of Sciences (SCNAT) and the Swiss Chemical Society (SCS) award travel scholarships to selected PhD students presenting at international conferences. As published recently in Chimia, Laura Klüpfel received an award to present at the Gordon Research Conference in Environmental Sciences: Water in Holderness, NH, USA. 

es-2014-00906d_0006
May 6, 2014

Characterizing the redox properties of biochar

In collaboration with Marco Keiluweit (Stanford) and Markus Kleber (Oregon State University), we published a new paper in Environ. Sci. Technol. on the redox properties and reactivities of biochars. By combining mediated electrochemical reduction and oxidation with spectroscopic and elemental analyses of two char thermosequences we provide evidence that the redox properties of low temperature chars are dominated by electron donating phenolic moieties and of high temperature chars by electron accepting quinone moieties. 

Redox properties of plant biomass-derived black carbon (biochar)
L. Klüpfel, M. Keiluweit, M. Kleber, M. Sander. Environ. Sci. Technol. 2014
DOI: 10.1021/es500906d
http://pubs.acs.org/doi/abs/10.1021/es500906d

es-2014-00535a_0007
April 22, 2014 - Earth Day!

Dissolved organic matter as a quencher and promoter of phototransformation


Lilli Janssen has a new paper in Environ. Sci. Technol. on the environmental photochemistry of tryptophan. In this study, dissolved organic matter was found to play a critical role, both in promoting and quenching the photooxidation of tryptophan. Through kinetic studies, experiments with model antioxidants, laser spectroscopy and kinetic modeling, a comprehensive picture of the different channels of reactivity of tryptophan were elucidated.

Dual Roles of Dissolved Organic Matter as Sensitizer and Quencher in the Photooxidation of Tryptophan
E. M.-L. Janssen, P. R. Erickson and K. McNeill
Environ. Sci. Technol. 2014
DOI: 10.1021/es500535a
http://pubs.acs.org/doi/abs/10.1021/es500535a

Kluepfel_TOC
February 27, 2014

Assessing electron transfer reversibility to humics over microbial reduction and O2 oxidation cycles

Laura Klüpfel and Michael Sander, in collaboration with Annette Piepenbrock and Andreas Kappler from the University of Tübingen, published their new work on the cyclic reduction and re-oxidation of humic substances in Nature Geoscience. The work shows that humic substances serve as fully regenerable and sustainable terminal electron acceptors for anaerobic microbial respiration in temporarily anoxic systems. Cyclic reduction and re-oxidation of HS is estimated to suppress the formation of significant amounts of methane in wetlands, including northern peatlands.

Humic substances as fully regenerable electron acceptors in recurrently anoxic environments.
L. Klüpfel, A. Piepenbrock, A. Kappler, M. Sander
Nature Geoscience 2014
DOI: 10.1038/ngeo2084
http://www.nature.com/ngeo/journal/v7/n3/full/ngeo2084.html

Press releases:
ETH Zurich; Uni Tübingen; European Association of Geochemistry

Lundeen_TOC
December 19, 2013

Assessing the photochemical reactivity of free and combined amino acids

In new work published in Environ. Sci. Technol., Rachel Lundeen investigates the photochemical reactivity differences between free and combined amino acids. The singlet oxygen (1O2) reaction kinetics of individual photooxidizable residues in the protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were measured; the results show that photodegradation kinetics of amino acid residues in an intact protein differ from those of free amino acids and that the 1O2 accessibility of a residue is actually predictive of the variation in 1O2 reactivities.

Reactivity Differences of Combined and Free Amino Acids: Quantifying the Relationship between Three-Dimensional Protein Structure and Singlet Oxygen Reaction Rates
R. Lundeen and K. McNeill
Environ. Sci. Technol. 2013
DOI: 10.1021/es404236c
http://pubs.acs.org/doi/abs/10.1021/es404236c

Sadowsky_TOC
December 17, 2013

Calculating the thermochemical properties of halogenated aromatics

The group’s work with halogenated organics continues with a new paper published in Environ. Sci. Technol. investigating the thermochemical properties of these important environmental contaminants. Research by Daniel Sadowsky, co-advised by Chris Cramer, uses a validated density functional protocol to calculate various thermochemical properties, such as bond dissociation enthalpies. The results highlight that fluorinated aromatics stand distinct from their chloro- and bromo- counterparts in terms of both their relative thermodynamic stability toward dehalogenation and how different substitution patterns give rise to relevant properties.

Thermochemical Factors Affecting the Dehalogenation of Aromatics
D. Sadowsky, K. McNeill, and C. Cramer
Environ. Sci. Technol. 2013
DOI: 10.1021/es404033y
http://pubs.acs.org/doi/abs/10.1021/es404033y

Gorski3_TOC
December 13, 2013

Further insights into the redox properties of structural Fe in clay minerals

In the third paper in a series published in Environ. Sci. Technol., collaborative work with Chris Gorski, previously from the Hofstetter lab at Eawag, further probes the redox properties of structural Fe in clay minerals and relates the structural Fe2+/
Fetotal fractions to fundamental redox properties (see also news item dated August 24, 2012). The collective data indicates that structural Fe in smectites is redox-active over wide reduction potential ranges and reduction potential relationships correlate well with both bulk and molecular-scale properties, including Fetotal content, layer charge, and quadrupole splitting values.


Redox Properties of Structural Fe in Clay Minerals: 3. Relationships between Smectite Redox and Structural Properties
C. Gorski, L. Klüpfel, A. Voegelin, M. Sander, and T. Hofstetter
Environ. Sci. Technol. 2013
DOI: 10.1021/es403824x
http://pubs.acs.org/doi/abs/10.1021/es403824x

Zukunftstag_Pic
November 26, 2013

Group hosts students for Swiss Future Day (Zukunftstag)

In mid-November, young students from across Switzerland are encouraged to accompany an adult to work to get ideas for future careers. This past Future Day, the group hosted a morning session for 14 students entitled “A Look into the Day of a Researcher.” After an introduction by Jeanne, Sandra, Sarah K., Rebekka, and Michael Z. all introduced the students to different aspects of their research projects in the lab. In the afternoon, two more groups of students from the ETH Equal Opportunity Program visited the lab, with Jeanne and Sarah K. acting as role models of women in science careers. All in all, the day was another successful and fun outreach event for the group.

Ratti_Award
November 22, 2013

Marco receives the IAGC Faure Presentation Award

At the recent International Symposium on Applied Isotope Geochemistry, Marco, co-advised by T. Hofstetter and S. Canonica at Eawag, was awarded the Faure Award for his excellent presentation entitled "Tracking photochemical transformation of chloroanilines in aquatic environments by compound-specific isotope analysis.” Congratulations to Marco for earning this prize, awarded for best student research presentation at each International Association of GeoChemistry (IAGC) conference.

Aeschbacher2013_TOC
November 21, 2013

Measuring dissolved organic matter redox state during water treatment

In collaboration with researchers from Eawag (Canonica and von Gunten groups), the Sander group applied their mediated electrochemical oxidation technique to successfully quantify the change in redox state of dissolved organic matter (DOM) during oxidation processes typically used in water treatment. The investigation, published in Environ. Sci. Technol. and co-authored by former group member Michael Aeschbacher, may have important applications in water treatment, as this technique can provide real-time information on the concentration and reactivity of the DOM in the water.


Chemical Oxidation of Dissolved Organic Matter by Chlorine Dioxide, Chlorine, And Ozone: Effects on Its Optical and Antioxidant Properties
J. Wenk, M. Aeschbacher, E. Salhi, S. Canonica, U. von Gunten and M. Sander
Environ. Sci. Technol. 2013
DOI: 10.1021/es402516b
http://pubs.acs.org/doi/abs/10.1021/es402516b

Sander_ReviewAward
November 5, 2013

Michael Sander receives ES&T 2013 Excellence in Review Award

Every year Environ. Sci. Technol. recognizes selected reviewers for their significant contributions to the journal over the past year. Based on his scholarly and timely reviews of submitted manuscripts, Michael Sander is among those recognized this year. Also among the winners is McNeill group alumnae Laura MacManus-Spencer. Congratulations and keep up with the great reviews!

ES&T 2013 Excellence in Review Award
DOI: 10.1021/es404543z
http://pubs.acs.org/doi/full/10.1021/es404543z

Eustis_TOC2013
November 4, 2013

Probing the quenching of excited triplet states by DOM

A new study in collaboration with the Canonica group at Eawag, published in Environ. Sci. Technol., probes the question of a possible interaction between the excited triplet states of organic contaminants and dissolved organic matter (DOM) from natural waters. Co-author and former group member Soren Eustis helped discover that dynamic quenching of excited triplet states does not occur significantly at DOM concentrations of a few milligrams carbon per liter. 

Quenching of Excited Triplet States by Dissolved Natural Organic Matter
J. Wenk, S. Eustis, S. Canonica and K. McNeill
Environ. Sci. Technol. 2013
DOI: 10.1021/es402668h
http://pubs.acs.org/doi/full/10.1021/es402668h

TOCforweb
October 31, 2013

Field demonstration of dark formation of hydroxyl radical

In previous work, Sarah Page reported a non-photochemical pathway for hydroxyl radical (•OH) formation during oxidation of reduced aquatic dissolved organic matter (DOM) and iron (see news item dated January 21, 2012). In a follow-up field study, recently published in Environ. Sci. Technol., Sarah demonstrated the formation pathway in natural aquatic environments. Estimates based on Sarah’s data suggests that at landscape scales, abiotic DOM oxidation by this dark •OH pathway may be as important to carbon cycling as bacterial oxidation of DOM in surface waters.


Dark formation of hydroxyl radical in arctic soil and surface waters
S. Page, G. Kling, M. Sander, K. Harrold, J. Logan, K. McNeill, and R. Cory
Environ. Sci. Technol. 2013
DOI: 10.1021/es4033265
http://pubs.acs.org/doi/abs/10.1021/es4033265

emily
September 19, 2013

Congratulations Dr. Emily Pelton!

Emily Pelton, a joint McNeill-Blank PhD student, successfully defended her PhD thesis on August 16 at the University of Minnesota.  Emily is now on the other side of the lectern as an instructor in the Minnesota Department of Chemistry.  She is pictured here on a visit to Switzerland in September 2009.  Congratulations, Emily!

Klupel_Prize
September 11, 2013

Laura awarded the Bernd Rendel Prize

The German Research Foundation (DFG) awards the Bernd Rendel Prize yearly to young scientists who make important and original contributions to fundamental geoscience research. This year, Laura Klüpfel was one of four recipients awarded for her research focusing on natural organic matter from soil, sediment and bogs. Under anoxic conditions, organic matter accepts electrons from anaerobic microbial respiration and upon subsequent re-aeration, transfers them to oxygen.

Scientifica_2013
September 4, 2013

Group participates in Zürich Science Day (Scientifica)

Over the past weekend, members of our EnvChem group, along with the Uchem group at Eawag, participated in Scientifica, the Zürich Science Day put on by ETH-Zürich and the University of Zürich. Our exhibition stand, developed by Jeanne Tomaszewski, displayed how chemicals from household products are degraded, or not, in a wastewater treatment plant and via photolysis in natural waters. Hundreds of visitors of all ages visited the stand, making this a successful outreach event for the group.

Rachel_Travel_Award
July 23, 2013

Rachel awarded the SCNAT/SCS Chemistry Travel Award

The Swiss Academy of Sciences (SCNAT) and the Swiss Chemical Society (SCS) award travel scholarships to selected PhD students presenting at international conferences. As published recently in Chimia, Rachel Lundeen received an award to present at the 245th ACS Meeting, Chemistry of Energy & Food, in New Orleans, USA. As there were a record number of applicants this year, congrats to Rachel!

ReneTribute
July 10, 2013

This month’s ES&T pays tribute to the research and education legacy of Prof. em. René Schwarzenbach


The latest issue of Environ. Sci. Technol. contains several touching commentaries by colleagues focusing on the René’s influence on The Book, Eawag, the Competence Center Environment and Sustainability (CCES), and the environmental science curriculum at ETH, now ranked the highest in Europe. The 36 included research articles highlight an ethos of Schwarzenbach, that a fundamental understanding of intermolecular interactions and chemical reactions is key to understand organic pollutants.


The issue has also been highlighted in ETH-Life and by an interview with Eawag.

Environ. Sci. Technol. 47(13) 2013
http://pubs.acs.org/toc/esthag/47/13

Baumgartner2013
 June 4, 2013

Complete hydrodehalogenation of polyhalogenated benzenes using rhodium-based catalyst

Continuing 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.


Complete Hydrodehalogenation of Polyfluorinated and Other Polyhalogenated Benzenes under Mild Catalytic Conditions
R. Baumgartner, G. Stieger, and K. McNeill
Environ. Sci. Technol. 2013
DOI: 10.1021/es401183v
http://pubs.acs.org/doi/abs/10.1021/es401183v

Gulkowska
 June 3, 2013

Covalent binding of a sulfonamide antibiotic to soil organic matter

Sulfonamide 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. 


Covalent Binding of Sulfamethazine to Natural and Synthetic Humic Acids: Assessing Laccase Catalysis and Covalent Bond Stability
A. Gulkowska, M. Sander. J. Hollender, and M. Krauss
Environ. Sci. Technol. 2013
DOI: 10.1021/es3044592
http://pubs.acs.org/doi/full/10.1021/es3044592

TOC_EST_award
April 30, 2013

Paul's paper honored as one of ES&T's best in 2012

Environmental 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.

Photochemical formation of brominated dioxins and other products of concern from hydroxlated polybrominated diphenyl ethers (OH-PBDEs)
P.R. Erickson, M. Grandbois, W.A. Arnold and K. McNeill
Environ. Sci. Technol. 2012
DOI: 10.1021/es3016183
http://pubs.acs.org/doi/abs/10.1021/es3016183

KliegmanGraphic
January 30, 2013

Insights into the involvement of radicals in triclosan phototransformation

Work 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.

Experimental and Theoretical Insights into the Involvement of Radicals in Triclosan Phototransformation
S. Kliegman, S.N. Eustis, W.A. Arnold, K. McNeill
Environ. Sci. Technol. 2013 DOI: 10.1021/es3041797
http://pubs.acs.org/doi/abs/10.1021/es3041797

core_toc
January 29, 2013

Research finding triclosan in Minnesotan lake sediment in the media

As 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.
Check out the video of Bill Arnold explaining the research: http://z.umn.edu/arnold 

Quantification of Triclosan, Chlorinated Triclosan Derivatives, and their Dioxin Photoproducts in Lacustrine Sediment Cores
C.T. Anger, C. Sueper, D.J. Blumentritt, K. McNeill, D.R. Engstrom, W.A. Arnold
Environ. Sci. Technol. 2013
DOI: 10.1021/es3045289
http://pubs.acs.org/doi/abs/10.1021/es3045289

BMP_PhD
October 19, 2012

Congratulations 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.

Spatial and Temporal Distribution of Singlet Oxygen in Lake Superior
B.M. Peterson, A.M. McNally, R.M. Cory, J.D. Thoemke, J.B. Cotner, and K. McNeill, Environ. Sci. Technol.2012, DOI: 10.1021/es301105e
http://pubs.acs.org/doi/abs/10.1021/es301105e

StateRiver_Graphic
October 9, 2012

Triclosan transformation products highlighted in The State of the River Report

The 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.
State of the River Report
Water Quality and River Health in the Metro Mississippi River
2012

Friends of the Mississippi River and U.S. National park Service
http://stateoftheriver.com/state-of-the-river-report/
Featured data from: Dioxin photoproducts of triclosan and its chlorinated derivatives in sediment cores. J. Buth, P. Steen, C. Sueper, D. Blumentritt, P. Vokelans, W. Arnold, and K. McNeill.  Environ. Sci. Technol. 2010
DOI:  10.1021/es1001105
http://pubs.acs.org/doi/full/10.1021/es1001105

Tomaszewski_graphic
September 3, 2012

Fate of transgenic proteins in soils

The 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
M. Sander, J.E. Tomaszewski, M. Madliger, and R.P. Schwarzenbach
Adsorption of insecticidal Cry1Ab protein to humic substances. 2. Influence of humic and fulvic acid charge and polarity characteristics
J.E. Tomaszewski, M. Madliger, J.A. Pedersen, R. P. Schwarzenbach, and M. Sander
Environ. Sci. Technol. 2012
DOI: 10.1021/es3022478 & 10.1021/es302248u
http://pubs.acs.org/doi/abs/10.1021/es3022478
http://pubs.acs.org/doi/abs/10.1021/es302248u

Baumgartner_graphic
August 29, 2012

Hydrodefluorination of fluorobenzene using rhodium-based catalyst

New 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.


Hydrodefluorination and Hydrogenation of Fluorobenzene under Mild Aqueous Conditions
R. Baumgartner and K. McNeill
Environ. Sci. Technol. 2012
DOI: 10.1021/es302188f
http://pubs.acs.org/doi/abs/10.1021/es302188f

Gorski_Graphic
August 24, 2012

Measuring redox properties of structural Fe in clay minerals

As 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
C. Gorski, M. Aeschbacher, D. Soltermann, A. Voegelin, B. Baeyens, M.M. Fernandes, T. Hofstetter, and M. Sander
Redox properties of structural Fe in clay minerals: 2. Electrochemical and spectroscopic characterization of electron transfer irreversibility in ferruginous smectite, SWa-1
C. Gorski, L. Klüpfel, A. Voegelin, M. Sander, and T. Hofstetter
Environ. Sci. Technol. 2012
DOI: 10.1021/es3020138 & 10.1021/es302014u
http://pubs.acs.org/doi/abs/10.1021/es3020138
http://pubs.acs.org/doi/abs/10.1021/es302014u

remucal_graphic
August 23, 2012

Investigating the composition of an aqueous humic substance

Recent 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
C.K. Remucal, R. Cory, M. Sander, and K. McNeill
Environ. Sci. Technol. 2012
DOI: 10.1021/es302468q
http://pubs.acs.org/doi/abs/10.1021/es302468q

SEP_VS_AK
July 25, 2012

Congratulations to Dr. Sarah Page

Congratulations 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.

erickson_graphic
July 25, 2012

Photochemical production of brominated dioxins

Hydroxylated 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.

Photochemical formation of brominated dioxins and other products of concern from hydroxlated polybrominated diphenyl ethers (OH-PBDEs)
P.R. Erickson, M. Grandbois, W.A. Arnold and K. McNeill
Environ. Sci. Technol. 2012
DOI: 10.1021/es3016183
http://pubs.acs.org/doi/abs/10.1021/es3016183

PetersonGraphic
June 21, 2012

Singlet oxygen production in waters of Lake Superior

The 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.

Spatial and Temporal Distribution of Singlet Oxygen in Lake Superior
B.M. Peterson, A.M. McNally, R.M. Cory, J.D. Thoemke, J.B. Cotner, and K. McNeill, Environ. Sci. Technol.2012, DOI: 10.1021/es301105e
http://pubs.acs.org/doi/abs/10.1021/es301105e

Aeschbacher_Figure
April 30, 2012

Antioxidant 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
http://dx.doi.org/10.1021/es300039h

ROS_review
April 27, 2012

New 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
http://dx.doi.org/10.1007/s00027-012-0251-x

es-2011-04496d_0001
March 19, 2012

Reduced 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
http://dx.doi.org/10.1021/es204496d

Aeschbacher1
February 12, 2012

Sander 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.
http://dx.doi.org/10.1021/es902627p

Co_I_TOC
February 9, 2012

Isolable 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
http://dx.doi.org/10.1021/ic201780c

dark_OH
January 21, 2012

Dark 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
http://dx.doi.org/10.1021/es203836f

Michi_Ae_Wallis
October 10, 2011

Dr. 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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