97 results on '"Norbert V. Heeb"'
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2. Brominated Flame Retardants – Endocrine-Disrupting Chemicals in the Swiss Environment
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Andreas C. Gereckea, Peter Schmid, Christian Bogdal, Martin Kohler, Markus Zennegg, and Norbert V. Heeb
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Brominated flame retardants ,Emerging contaminants ,Endocrine disruptors ,Persistent organic pollutants ,Chemistry ,QD1-999 - Abstract
Brominated flame retardants (BFR) are additives used to protect plastic materials and textiles against ignition. As some widely used BFR have chemical structures similar to well known endocrine disruptors such as polychlorinated biphenyls (PCB) or bisphenol A, adverse effects were also presumed for BFR. When the NRP50 programme started in 2001, the sparse knowledge on environmental behavior and toxicology of BFR did not allow a proper assessment of the risks associated with the widespread use of these chemicals. Therefore, we proposed to address questions such as the exposure of animals and humans, temporal trends in the environment as well as transformation and transport processes of BFR. Concentrations of BFR in wildlife and humans in Switzerland today pose no serious concerns for negative health effects according to the current knowledge on the toxicity of BFR. However, negative health effects cannot be ruled out in the future, since some BFR persist in the environment and their concentrations in freshwater lake sediments are increasing rapidly. The development of environmentally safe alternatives to these chemicals will be an important issue for the future.
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- 2008
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3. Environmental impact of rejuvenators in asphalt mixtures containing high reclaimed asphalt content
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Regula Haag, María Isabel Vera Muñoz, Lily D. Poulikakos, R. Figi, Martins Zaumanis, Norbert V. Heeb, Maria Chiara Cavalli, and C. Schreiner
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050210 logistics & transportation ,Asphalt pavement ,Waste management ,Asphalt ,021105 building & construction ,0502 economics and business ,05 social sciences ,0211 other engineering and technologies ,Environmental science ,Environmental impact assessment ,02 engineering and technology ,Leaching (metallurgy) ,Civil and Structural Engineering - Abstract
The use of reclaimed asphalt pavement (RAP) is of increasing importance due to fast-growing amounts of demolished road materials. However, reclaimed asphalt can contain relevant amounts of pollutan...
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- 2021
4. Enzymatic synthesis and formation kinetics of mono- and di-hydroxylated chlorinated paraffins with the bacterial dehalogenase LinB from Sphingobium indicum
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Norbert V. Heeb, Davide Bleiner, Hans-Peter E. Kohler, Susanne Kern, Flurin Mathis, Marco C. Knobloch, and Thomas Fleischmann
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Environmental Engineering ,Halogenation ,Dihydroxylated chloroparaffins (CP-diols) ,Health, Toxicology and Mutagenesis ,Kinetics ,In-vitro CP transformation ,Hydroxylated chloroparaffins (CP-ols) ,Hydroxylation ,chemistry.chemical_compound ,Reaction rate constant ,Chlorinated paraffins ,Hydrocarbons, Chlorinated ,polycyclic compounds ,Humans ,Environmental Chemistry ,Organic chemistry ,Persistent organic pollutants (POPs) ,Dehalogenase ,chemistry.chemical_classification ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,Pollution ,540: Chemie ,Sphingomonadaceae ,Transformation (genetics) ,Enzyme ,chemistry ,Paraffin ,Enzymatic dehalohydroxylation ,Environmental Monitoring ,Sphingobium indicum - Abstract
Transformation studies of chlorinated paraffins (CPs) and the effects of CP transformation products on humans, biota and environment are rare. The focus here is on hydroxylation reactions. As for polyhalogenated persistent organic pollutants (POPs) in general, hydroxylation reactions convert lipophilic material to more polar compounds with increased mobility. We investigated the in-vitro transformation of single-chain CP-mixtures to hydroxylated products with the dehalogenase LinB from Sphingobium indicum. C11-, C12- and C13-single-chain CP-homologues were exposed to LinB and mono-hydroxylated (CP-ols) and di-hydroxylated (CP-diols) transformation products were formed. Liquid-chromatography coupled to mass-spectrometry (LC-MS) was used to detect hydroxylated products and separate them from the starting material. The presented data can be used to identify these CP-ol and CP-diol homologues in other samples. Hydroxylated products had lower chlorination degrees (nCl) than respective CP-starting-materials. Reactive and persistent CP-material was found in each homologue group. Reactive material is converted within hours by LinB, while more persistent CPs are transformed within days. Homologue-specific kinetic models were established to simulate the stepwise hydroxylation of persistent CPs to mono- and di-hydroxylated products. First-order rate constants for the formation of CP-ols (k1) and CP-diols (k2) were deduced for different homologues. Lower-chlorinated CP-ols did not accumulate to large extent and were transformed quickly to CP-diols, while higher-chlorinated CP-ols and -diols both accumulated. By enzymatic transformation of single-chain CPs with LinB, we synthesized unique sets of mono- and di-hydroxylated materials, which can be used as analytical standards and as starting materials for metabolic, toxicity and environmental fate studies.
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- 2021
5. Chemical synthesis and characterization of single-chain C18-chloroparaffin materials with defined degrees of chlorination
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Susanne Kern, Davide Bleiner, Norbert V. Heeb, Jannik Sprengel, Regula Haag, Flurin Mathis, Walter Vetter, and Marco C. Knobloch
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chemistry.chemical_classification ,Environmental Engineering ,Chemistry ,Health, Toxicology and Mutagenesis ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,Sulfuryl chloride ,Fractionation ,Pollution ,Chemical synthesis ,Long-chain chlorinated paraffins (LCCPs) ,540: Chemie ,Standard material ,chemistry.chemical_compound ,Hydrocarbon ,Chlorinated paraffins ,Sulfite ,Chlorinated paraffins (CPs) ,Mass spectrum ,Proton NMR ,Environmental Chemistry ,Organic chemistry ,Single-chain CPs ,Chlorinated olefins (COs) - Abstract
Technical chlorinated paraffins (CPs) are produced via radical chlorination of n-alkane feedstocks with different carbon chain-lengths (∼C10–C30). Short-chain CPs (SCCPs, C10–C13) are classified as persistent organic pollutants (POPs) under the Stockholm Convention. This regulation has induced a shift to use longer-chain CPs as substitutes. Consequently, medium-chain (MCCPs, C14–C17) and long-chain (LCCPs, C > 17) CPs have become dominant homologues in recent environmental samples. However, no suitable LCCP-standard materials are available. Herein, we report on the chemical synthesis of single-chain C18-CP materials, starting with pure n-alkane and sulfuryl chloride (SO2Cl2). Fractionation of the crude product by normal-phase liquid-chromatography and pooling of suitable fractions yielded in four C18-CP-materials with different chlorination degrees (mCl,EA = 39–52%). In addition, polar side-products, tentatively identified as sulfite-, sulfate- and bis-sulfate-diesters, were separated from CPs. The new single-chain materials were characterized by LC-MS, 1H NMR and EA. LC-MS provided Relative retention times for different C18-CP homologues and side-products. Mathematical deconvolution of full-scan mass spectra revealed the presence of chloroparaffins (57–93%) and chloroolefins (COs, 7–26%) in the four single-chain C18-CP-materials. Homologue distributions and chlorination degrees were deduced for CPs and COs. 1H NMR revealed chemical shift ranges of mono-chlorinated (δ = 3.2–5.3 ppm) and non-chlorinated (δ = 1.0–3.2 ppm) hydrocarbon moieties. The synthesized C18 single-chain standard materials and respective spectroscopic data are useful to identify and quantify LCCPs in various materials and environmental samples. CP- and CO-distributions resemble the ones of existing SCCP and MCCP reference materials and technical mixtures. Furthermore, these materials now allow specific studies on the environmental fate and the transformation of long-chain chloroparaffins and chloroolefins.
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- 2021
6. Chemical synthesis and characterization of single-chain C
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Marco C, Knobloch, Jannik, Sprengel, Flurin, Mathis, Regula, Haag, Susanne, Kern, Davide, Bleiner, Walter, Vetter, and Norbert V, Heeb
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China ,Halogenation ,Paraffin ,Hydrocarbons, Chlorinated ,Mass Spectrometry ,Environmental Monitoring - Abstract
Technical chlorinated paraffins (CPs) are produced via radical chlorination of n-alkane feedstocks with different carbon chain-lengths (∼C
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- 2021
7. Transformation of short-chain chlorinated paraffins and olefins with the bacterial dehalogenase LinB from Sphingobium Indicum - Kinetic models for the homologue-specific conversion of reactive and persistent material
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Susanne Kern, Flurin Mathis, Lena Schinkel, Marco C. Knobloch, Davide Bleiner, Norbert V. Heeb, and Hans-Peter E. Kohler
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Environmental Engineering ,Health, Toxicology and Mutagenesis ,0208 environmental biotechnology ,02 engineering and technology ,010501 environmental sciences ,Alkenes ,01 natural sciences ,Catalysis ,Chlorinated paraffins ,polycyclic compounds ,Hydrocarbons, Chlorinated ,Environmental Chemistry ,Organic chemistry ,Reactivity (chemistry) ,Persistent organic pollutants (POPs) ,Chlorinated olefins (COs) ,0105 earth and related environmental sciences ,Dehalogenase ,Chemistry ,Public Health, Environmental and Occupational Health ,Halogenation ,General Medicine ,General Chemistry ,Pollution ,First-order kinetic model ,660: Technische Chemie ,020801 environmental engineering ,Sphingomonadaceae ,Kinetics ,Paraffin ,Chlorinated paraffins (CPs) ,Enzymatic dechlorination ,Reactive material ,Haloalkane dehalogenase ,Sphingobium indicum ,Environmental Monitoring - Abstract
Structure, reactivity and physico-chemical properties of polyhalogenated compounds determine their up-take, transport, bio-accumulation, transformation and toxicity and their environmental fate. In technical mixtures of chlorinated paraffins (CPs), these properties are distributed due to the presence of thousands of homologues. We hypothesized that roles of CP dehalogenation reactions, catalyzed by the haloalkane dehalogenase LinB, depend on structural properties of the substrates, e.g. chlorination degree and carbon-chain length. We exposed mixtures of chlorinated undecanes, dodecanes and tridecanes in-vitro to LinB from Sphingobium Indicum bacteria. These single-chain CP-materials also contain small amounts of chlorinated olefins (COs), which can be distinct by mathematical deconvolution of respective mass-spectra. With this procedure, we obtained homologue-specific transformation kinetics of substrates differing in saturation degree, chlorination degree and carbon chain-length. For all homologues, two-stage first-order kinetic models were established, which described the faster conversion of reactive material and the slower transformation of more persistent material. Half-lifes of 0.5–3.2 h and 56–162 h were determined for more reactive and more persistent CP-material. Proportions of persistent material increased steadily from 18 to 67% for lower (Cl6) to higher (Cl11) chlorinated paraffins and olefins. Conversion efficiencies decreased with increasing chlorination degree from 97 to 70%. Carbon-chain length had only minor effects on transformation rates. Hence, the conversion was faster and more efficient for lower-chlorinated material, and slower for higher-chlorinated and longer-chained CPs and COs. Current legislation has banned short-chain chlorinated paraffins (SCCPs) and forced a transition to longer-chain CPs. This may be counterproductive with regard to enzymatic transformation with LinB.
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- 2021
8. Transformation of short-chain chlorinated paraffins by the bacterial haloalkane dehalogenase LinB : Formation of mono- and di-hydroxylated metabolites
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Marco C. Knobloch, Peter Lienemann, Norbert V. Heeb, Iris Schilling, Hans-Peter E. Kohler, Davide Bleiner, and Lena Schinkel
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Environmental Engineering ,Hydroxylated chlorinated paraffins ,Halogenation ,Hydrolases ,Health, Toxicology and Mutagenesis ,0208 environmental biotechnology ,02 engineering and technology ,010501 environmental sciences ,medicine.disease_cause ,Hydroxylation ,01 natural sciences ,Chloride ,Adduct ,Chlorinated paraffins ,Liquid chromatography–mass spectrometry ,medicine ,Escherichia coli ,Hydrocarbons, Chlorinated ,Environmental Chemistry ,Organic chemistry ,Persistent organic pollutants (POPs) ,Haloalkane dehalogenase LinB ,Chlorinated olefins (COs) ,0105 earth and related environmental sciences ,Chemistry ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,Pollution ,660: Technische Chemie ,020801 environmental engineering ,Hydrocarbons, Brominated ,Sphingomonadaceae ,Paraffin ,Chlorinated paraffins (CPs) ,Mass spectrum ,Biocatalysis ,Environmental Pollutants ,Heterologous expression ,Hexachlorocyclohexane ,Haloalkane dehalogenase ,medicine.drug ,Environmental Monitoring - Abstract
Short-chain chlorinated paraffins (SCCPs) are listed as persistent organic pollutants (POPs) under the Stockholm Convention. Such substances are toxic, bioaccumulating, transported over long distances and degrade slowly in the environment. Certain bacterial strains of the Sphingomonadacea family are able to degrade POPs, such as hexachlorocyclohexanes (HCHs) and hexabromocyclododecanes (HBCDs). The haloalkane dehalogenase LinB, expressed in certain Sphingomonadacea, is able to catalyze the transformation of haloalkanes to hydroxylated compounds. Therefore, LinB is a promising candidate for conversion of SCCPs. Hence, a mixture of chlorinated tridecanes was exposed in vitro to LinB, which was obtained through heterologous expression in Escherichia coli. Liquid chromatography mass spectrometry (LC-MS) was used to analyze chlorinated tridecanes and their transformation products. A chloride-enhanced soft ionization method, which favors the formation of chloride adducts [M+Cl]- without fragmentation, was applied. Mathematical deconvolution was used to distinguish interfering mass spectra of paraffinic, mono-olefinic and di-olefinic compounds. Several mono- and di-hydroxylated products including paraffinic, mono-olefinic and di-olefinic compounds were found after LinB exposure. Mono- (rt = 5.9-6.9 min) and di-hydroxylated (rt = 3.2-4.5 min) compounds were separated from starting material (rt = 7.7-8.5 min) by reversed phase LC. Chlorination degrees of chlorinated tridecanes increased during LinB-exposure from nCl = 8.80 to 9.07, indicating a preferential transformation of lower chlorinated (Cl
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- 2021
9. Determination of chlorinated paraffins (CPs): Analytical conundrums and the pressing need for reliable and relevant standards
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Ronan Cariou, Anouk Lentjes, Kerstin Krätschmer, Norbert V. Heeb, Louise M. van Mourik, Jannik Sprengel, Alwyn R. Fernandes, Caroline Dirks, Walter Vetter, E&H: Environmental Bioanalytical Chemistry, and AIMMS
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Configurationally defined standards ,China ,Environmental Engineering ,Health, Toxicology and Mutagenesis ,Mass Spectrometry ,Chlorinated paraffins ,Hydrocarbons, Chlorinated ,Humans ,Environmental Chemistry ,Instrumentation (computer programming) ,SCCP/MCCP/LCCP ,Single-chain CP mixtures ,Team Organic Contaminants ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,Pollution ,Mass spectrometric ,Relevant chlorine substitution ,Paraffin ,Labelled CP standards ,Environmental science ,Biochemical engineering ,Chlorine ,Environmental Monitoring - Abstract
The determination of chlorinated paraffins (CPs) has posed an intractable challenge in analytical chemistry for over three decades. The combination of an as yet unspecifiable number (tens - hundreds of thousands) of individual congeners in mass produced commercial CP mixtures and the steric interactions between them, contrive to defy efforts to characterise their residual occurrences in environmental compartments, food and human tissues. However, recent advances in instrumentation (mass spectrometric detectors and nuclear magnetic resonance), combined with interlaboratory studies, have allowed a better insight into the nature of the conundrums. These include the variability of results, even between experienced laboratories when there is insufficient matching between analytical standards and occurrence profiles, the poor (or no) response of some instrumentation to some CP congener configurations (multiple terminal chlorines or < four chlorines) and the occurrence of chlorinated olefins in commercial mixtures. The findings illustrate some limitations in the existing set of commercially available standards. These include cross-contamination of some standards (complex CP mixtures), an insufficient number of single chain standards (existing ones do not fully reflect food/biota occurrences), lack of homologue group standards and unsuitability of some configurationally defined CP congeners/labelled standards (poor instrument response and a smaller likelihood of occurrence in commercial mixtures). They also indicate an underestimation in reported occurrences arising from those CPs that are unresponsive during measurement. A more extensive set of standards is suggested and while this might not be a panacea for accurate CP determination, it would reduce the layers of complexity inherent in the analysis.
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- 2022
10. Kinetics and stereochemistry of LinB-catalyzed δ-HBCD transformation: Comparison of in vitro and in silico results
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Hans-Peter E. Kohler, Norbert V. Heeb, Manuel Mazenauer, Simon Wyss, Birgit Geueke, and Peter Lienemann
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0301 basic medicine ,Environmental Engineering ,Stereochemistry ,Health, Toxicology and Mutagenesis ,Kinetics ,010501 environmental sciences ,01 natural sciences ,Michaelis–Menten kinetics ,Catalysis ,03 medical and health sciences ,chemistry.chemical_compound ,Bromide ,Environmental Chemistry ,Computer Simulation ,Enzyme kinetics ,0105 earth and related environmental sciences ,Chemistry ,Public Health, Environmental and Occupational Health ,Stereoisomerism ,General Medicine ,General Chemistry ,Pollution ,Hydrocarbons, Brominated ,Enzyme binding ,030104 developmental biology ,Docking (molecular) ,Enantiomer ,Haloalkane dehalogenase - Abstract
LinB is a haloalkane dehalogenase found in Sphingobium indicum B90A, an aerobic bacterium isolated from contaminated soils of hexachlorocyclohexane (HCH) dumpsites. We showed that this enzyme also converts hexabromocyclododecanes (HBCDs). Here we give new insights in the kinetics and stereochemistry of the enzymatic transformation of δ-HBCD, which resulted in the formation of two pentabromocyclododecanols (PBCDols) as first- (P1δ, P2δ) and two tetrabromocyclododecadiols (TBCDdiols) as second-generation products (T1δ, T2δ). Enzymatic transformations of δ-HBCD, α1-PBCDol, one of the transformation products, and α2-PBCDol, its enantiomer, were studied and modeled with Michaelis-Menten (MM) kinetics. Respective MM-parameters KM, vmax, kcat/KM indicated that δ-HBCD is the best LinB substrate followed by α2- and α1-PBCDol. The stereochemistry of these transformations was modeled in silico, investigating respective enzyme-substrate (ES) and enzyme-product (EP) complexes. One of the four predicted ES-complexes led to the PBCDol product P1δ, identical to α2-PBCDol with the 1R,2R,5S,6R,9R,10S-configuration. An SN2-like substitution of bromine at C6 of δ-HBCD by Asp-108 of LinB and subsequent hydrolysis of the alkyl-enzyme led to α2-PBCDol. Modeling results further indicate that backside attacks at C1, C9 and C10 are reasonable too, selectively binding leaving bromide ions in a halide pocket found in LinB. Docking with α2-PBCDol, also allowed productive enzyme binding. A TBCD-1,5-diol with the 1S,2S,5R,6R,9S,10R-configuration is the predicted second-generation product T1δ. In conclusion, in vitro- and in silico findings now allow a detailed description of step-wise enzymatic dehalohydroxylation reactions of δ-HBCD to specific PBCDols and TBCDdiols at A-resolution and predictions of their stereochemistry.
- Published
- 2018
11. Gas-phase composition and secondary organic aerosol formation from standard and particle filter-retrofitted gasoline direct injection vehicles investigated in a batch and flow reactor
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Urs Baltensperger, Pierre Comte, André S. H. Prévôt, Felix Klein, Emily A. Bruns, Imad El Haddad, Jay G. Slowik, Josef Dommen, Nivedita K. Kumar, Jan Czerwinski, Simone M. Pieber, Alejandro Keller, Deepika Bhattu, Doǧuşhan Kılıç, and Norbert V. Heeb
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Atmospheric Science ,Diesel particulate filter ,010504 meteorology & atmospheric sciences ,Chemistry ,Xylene ,Analytical chemistry ,010501 environmental sciences ,Particulates ,01 natural sciences ,Ethylbenzene ,Toluene ,lcsh:QC1-999 ,Aerosol ,lcsh:Chemistry ,chemistry.chemical_compound ,lcsh:QD1-999 ,Aerosol mass spectrometry ,Gasoline ,lcsh:Physics ,0105 earth and related environmental sciences - Abstract
Gasoline direct injection (GDI) vehicles have recently been identified as a significant source of carbonaceous aerosol, of both primary and secondary origin. Here we investigated primary emissions and secondary organic aerosol (SOA) from four GDI vehicles, two of which were also retrofitted with a prototype gasoline particulate filter (GPF). We studied two driving test cycles under cold- and hot-engine conditions. Emissions were characterized by proton transfer reaction time-of-flight mass spectrometry (gaseous non-methane organic compounds, NMOCs), aerosol mass spectrometry (sub-micron non-refractory particles) and light attenuation measurements (equivalent black carbon (eBC) determination using Aethalometers) together with supporting instrumentation. Atmospheric processing was simulated using the PSI mobile smog chamber (SC) and the potential aerosol mass oxidation flow reactor (OFR). Overall, primary and secondary particulate matter (PM) and NMOC emissions were dominated by the engine cold start, i.e., before thermal activation of the catalytic after-treatment system. Trends in the SOA oxygen to carbon ratio (O : C) for OFR and SC were related to different OH exposures, but divergences in the H : C remained unexplained. SOA yields agreed within experimental variability between the two systems, with a tendency for higher values in the OFR than in the SC (or, vice versa, lower values in the SC). A few aromatic compounds dominated the NMOC emissions, primarily benzene, toluene, xylene isomers/ethylbenzene and C3-benzene. A significant fraction of the SOA was explained by those compounds, based on comparison of effective SOA yield curves with those of toluene, o-xylene and 1,2,4-trimethylbenzene determined in our OFR, as well as others from literature. Remaining discrepancies, which were smaller in the SC and larger in the OFR, were up to a factor of 2 and may have resulted from diverse reasons including unaccounted precursors and matrix effects. GPF retrofitting significantly reduced primary PM through removal of refractory eBC and partially removed the minor POA fraction. At cold-started conditions it did not affect hydrocarbon emission factors, relative chemical composition of NMOCs or SOA formation, and likewise SOA yields and bulk composition remained unaffected. GPF-induced effects at hot-engine conditions deserve attention in further studies.
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- 2018
12. Co-formation and co-release of genotoxic PAHs, alkyl-PAHs and soot nanoparticles from gasoline direct injection vehicles
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Joachim Mohn, Peter Honegger, Pierre Comte, Norbert V. Heeb, Regula Haag, Jan Czerwinski, Kerstin Zeyer, and María Isabel Vera Muñoz
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Atmospheric Science ,Diesel exhaust ,010504 meteorology & atmospheric sciences ,010501 environmental sciences ,medicine.disease_cause ,Combustion ,01 natural sciences ,Soot ,Diesel fuel ,Environmental chemistry ,medicine ,Environmental science ,Particle ,Air quality index ,Gasoline direct injection ,Driving cycle ,0105 earth and related environmental sciences ,General Environmental Science - Abstract
Gasoline direct injection (GDI) vehicles quickly replace traditional port-fuel injection (PFI) vehicles in Europe reaching about 50 million vehicles on roads in 2020. GDI vehicles release large numbers of soot nanoparticles similar to conventional diesel vehicles without particle filters. These exhausts will increasingly affect air quality in European cities. We hypothesized that such particles are released together with polycyclic aromatic hydrocarbons (PAHs) formed under the same combustion conditions. Emission data of a fleet of 7 GDI vehicles (1.2–1.8 L) including Euro-3,-4,-5 and -6 technologies revealed substantial particle emissions on average of 2.5 × 1012 particles km−1 in the cold worldwide harmonized light vehicle test cycle (cWLTC), the future European legislative driving cycle. Particle emissions increased 2–3 orders of magnitude during acceleration like CO, indicating that transient driving produces fuel-rich conditions with intense particle formation. For comparison, an Euro-5 diesel vehicle (1.6 L) equipped with a particle filter released 3.9 × 1010 particles km−1 (cWLTC), clearly within the Euro-5/6 limit value of 6.0 × 1011 particles km−1 and 64-fold below the GDI fleet average. PAH and alkyl-PAH emissions of the GDI vehicles also exceeded those of the diesel vehicle. Mean GDI emissions of 2-, 3-, 4-, 5- and 6-ring PAHs in the cWLTC were 240, 44, 5.8, 0.5 and 0.4 μg km−1, those of the diesel vehicle were only 8.8, 7.1, 8.6, 0.02 and 0.02 μg km−1, respectively. Thus mean PAH emissions of the GDI fleet were 2 orders of magnitude higher than the bench mark diesel vehicle. A comparison of the toxicity equivalent concentrations (TEQ) in the cWLTC of the GDI fleet and the diesel vehicle revealed that GDI vehicles released 200–1700 ng TEQ m−3 genotoxic PAHs, being 6–40 times higher than the diesel vehicle with 45 ng TEQ km−1. The co-release of genotoxic PAHs adsorbed on numerous soot nanoparticles is critical due to the Trojan horse effect describing the property of sub-200 nm particles being deposited in the alveoli transporting genotoxic compounds into the lung. These nanoparticles are persistent and may eventually penetrate the alveolar membrane reaching the blood circulation system. We showed that all GDI vehicles tested released large numbers of nanoparticles carrying substantial loads of genotoxic PAHs. If non-treated diesel exhaust is considered as class-1 carcinogen by the WHO inducing lung cancer in humans, these GDI vehicle exhausts may be a major health risk too for those exposed to them corroborating the progress achieved with current diesel vehicles, now equipped with efficient particle filters.
- Published
- 2018
13. Carboxylate Functional Groups Mediate Interaction with Silver Nanoparticles in Biofilm Matrix
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Davide Bleiner, Norbert V. Heeb, Olga Sambalova, Yucheng Zhang, Kerstin Thorwarth, Alexandra Kroll, and Andreas Borgschulte
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Reducing agent ,General Chemical Engineering ,Biofilm ,Nucleation ,Biofilm matrix ,02 engineering and technology ,General Chemistry ,010501 environmental sciences ,engineering.material ,021001 nanoscience & nanotechnology ,01 natural sciences ,Article ,Silver nanoparticle ,lcsh:Chemistry ,Silver nitrate ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,lcsh:QD1-999 ,engineering ,Biopolymer ,Carboxylate ,0210 nano-technology ,0105 earth and related environmental sciences - Abstract
Biofilms causing medical conditions or interfering with technical applications can prove undesirably resistant to silver nanoparticle (AgNP)-based antimicrobial treatment, whereas beneficial biofilms may be adversely affected by the released silver nanoparticles. Isolated biofilm matrices can induce reduction of silver ions and stabilization of the formed nanosilver, thus altering the exposure conditions. We thus study the reduction of silver nitrate solution in model experiments under chemically defined conditions as well as in stream biofilms. Formed silver nanoparticles are characterized by state-of-the art methods. We find that isolated biopolymer fractions of biofilm organic matrix are capable of reducing ionic Ag, whereas other isolated fractions are not, meaning that biopolymer fractions contain both reducing agent and nucleation seed sites. In all of the investigated systems, we find that silver nanoparticle–biopolymer interface is dominated by carboxylate functional groups. This suggests that the mechanism of nanoparticle formation is of general nature. Moreover, we find that glucose concentration within the biofilm organic matrix correlates strongly with the nanoparticle formation rate. We propose a simple mechanistic explanation based on earlier literature and the experimental findings. The observed generality of the extracellular polymeric substance/AgNP system could be used to improve the understanding of impact of Ag+ on aqueous ecosystems, and consequently, to develop biofilm-specific medicines and bio-inspired water decontaminants.
- Published
- 2018
14. Deconvolution of Mass Spectral Interferences of Chlorinated Alkanes and Their Thermal Degradation Products: Chlorinated Alkenes
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Kristopher McNeill, Christian Bogdal, Norbert V. Heeb, Peter Lienemann, Lena Schinkel, and Sandro Lehner
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Isotope ,Chemistry ,010401 analytical chemistry ,Analytical chemistry ,Atmospheric-pressure chemical ionization ,010501 environmental sciences ,Contamination ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Chlorinated paraffins ,Quadrupole ,Thermal ,Degradation (geology) ,Deconvolution ,0105 earth and related environmental sciences - Abstract
Chlorinated paraffins (CPs) are high production volume chemicals and ubiquitous environmental contaminants. CPs are produced and used as complex mixtures of polychlorinated n-alkanes containing thousands of isomers, leading to demanding analytical challenges. Due to their high degree of chlorination, CPs have highly complex isotopic mass patterns that often overlap, even when applying high resolution mass spectrometry. This is further complicated in the presence of degradation products such as chlorinated alkenes (CP-enes). CP-enes are formed by dehydrochlorination of CPs and are expected thermal degradation products in some applications of CPs, for example, as metal working fluids. A mathematical method is presented that allows deconvolution of the strongly interfered measured isotope clusters into linear combinations of isotope clusters of CPs and CP-enes. The analytical method applied was direct liquid injection into an atmospheric pressure chemical ionization source, followed by quadrupole time-of-flight mass spectrometry (APCI-qTOF-MS), operated in full scan negative ion mode. The mathematical deconvolution method was successfully applied to a thermally aged polychlorinated tridecane formulation (Cl
- Published
- 2017
15. Hazard identification of exhausts from gasoline-ethanol fuel blends using a multi-cellular human lung model
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Christoph Bisig, Pierre Comte, Norbert V. Heeb, Alke Petri-Fink, Loretta Müller, Andreas Mayer, Michèle Roth, Barbara Rothen-Rutishauser, and Jan Czerwinski
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Diesel exhaust ,010504 meteorology & atmospheric sciences ,Cell Survival ,Gene Expression ,Gasoline exhaust ,010501 environmental sciences ,medicine.disease_cause ,Models, Biological ,01 natural sciences ,Biochemistry ,Gasoline-ethanol blends ,Hazardous Substances ,DNA Adducts ,Diesel fuel ,chemistry.chemical_compound ,In vitro ,Environmental Science(all) ,medicine ,Humans ,Ethanol fuel ,Multi-cellular lung model ,Food science ,Gasoline ,Lung ,Cells, Cultured ,NOx ,Vehicle Emissions ,0105 earth and related environmental sciences ,General Environmental Science ,Microscopy, Confocal ,Ethanol ,E10, E85 ,Chemistry ,Macrophages ,Epithelial Cells ,Dendritic Cells ,Glutathione ,Coculture Techniques ,E85 ,Oxidative stress - Abstract
Ethanol can be produced from biomass and as such is renewable, unlike petroleum-based fuel. Almost all gasoline cars can drive with fuel containing 10% ethanol (E10), flex-fuel cars can even use 85% ethanol (E85). Brazil and the USA already include 10–27% ethanol in their standard fuel by law. Most health effect studies on car emissions are however performed with diesel exhausts, and only few data exists for other fuels. In this work we investigated possible toxic effects of exhaust aerosols from ethanol-gasoline blends using a multi-cellular model of the human lung. A flex-fuel passenger car was driven on a chassis dynamometer and fueled with E10, E85, or pure gasoline (E0). Exhausts obtained from a steady state cycle were directly applied for 6 h at a dilution of 1:10 onto a multi-cellular human lung model mimicking the bronchial compartment composed of human bronchial cells (16HBE14o-), supplemented with human monocyte-derived dendritic cells and monocyte-derived macrophages, cultured at the air-liquid interface. Biological endpoints were assessed after 6 h post incubation and included cytotoxicity, pro-inflammation, oxidative stress, and DNA damage. Filtered air was applied to control cells in parallel to the different exhausts; for comparison an exposure to diesel exhaust was also included in the study. No differences were measured for the volatile compounds, i.e. CO, NOx, and T.HC for the different ethanol supplemented exhausts. Average particle number were 6×102 #/cm3 (E0), 1×105 #/cm3 (E10), 3×103 #/cm3 (E85), and 2.8×106 #/cm3 (diesel). In ethanol-gasoline exposure conditions no cytotoxicity and no morphological changes were observed in the lung cell cultures, in addition no oxidative stress - as analyzed with the glutathione assay - was measured. Gene expression analysis also shows no induction in any of the tested genes, including mRNA levels of genes related to oxidative stress and pro-inflammation, as well as indoleamine 2,3-dioxygenase 1 (IDO-1), transcription factor NFE2-related factor 2 (NFE2L2), and NAD(P)H dehydrogenase [quinone] 1 (NQO1). Finally, no DNA damage was observed with the OxyDNA assay. On the other hand, cell death, oxidative stress, as well as an increase in pro-inflammatory cytokines was observed for cells exposed to diesel exhaust, confirming the results of other studies and the applicability of our exposure system. In conclusion, the tested exhausts from a flex-fuel gasoline vehicle using different ethanol-gasoline blends did not induce adverse cell responses in this acute exposure. So far ethanol-gasoline blends can promptly be used, though further studies, e.g. chronic and in vivo studies, are needed.
- Published
- 2016
- Full Text
- View/download PDF
16. Transformation of ε-HBCD with the Sphingobium Indicum enzymes LinA1, LinA2 and LinATM, a triple mutant of LinA2
- Author
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Rup Lal, Norbert V. Heeb, Thomas Fleischmann, Jasmin Hubeli, Peter Lienemann, Hans-Peter E. Kohler, and Namita Nayyar
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Environmental Engineering ,Stereochemistry ,Health, Toxicology and Mutagenesis ,0208 environmental biotechnology ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,chemistry.chemical_compound ,Biotransformation ,Escherichia coli ,Environmental Chemistry ,Enzyme kinetics ,Flame Retardants ,0105 earth and related environmental sciences ,chemistry.chemical_classification ,Public Health, Environmental and Occupational Health ,Substrate (chemistry) ,Stereoisomerism ,General Medicine ,General Chemistry ,Pollution ,Hydrocarbons, Brominated ,020801 environmental engineering ,Amino acid ,Sphingomonadaceae ,Enzyme ,chemistry ,Enantiomer ,Lindane ,Hexachlorocyclohexane ,Sphingobium indicum - Abstract
Hexabromocyclododecanes (HBCDs) were used as flame-retardants until their ban in 2013. Among the 16 stereoisomers known, e-HBCD has the highest symmetry. This makes e-HBCD an interesting substrate to study the selectivity of biotransformations. We expressed three LinA dehydrohalogenase enzymes in E. coli bacteria, two wild-type, originating from Sphingobium indicum B90A bacteria and LinATM, a triple mutant of LinA2, with mutations of L96C, F113Y and T133 M. These enzymes are involved in the hexachlorocyclohexane (HCH) metabolism, specifically of the insecticide γ-HCH (Lindane). We studied the reactivity of those eight HBCD stereoisomers found in technical HBCD. Furthermore, we compared kinetics and selectivity of these LinA variants with respect to e-HBCD. LC-MS data indicate that all enzymes converted e-HBCD to pentabromocyclododecenes (PBCDens). Transformations followed Michaelis-Menten kinetics. Rate constants kcat and enzyme specificities kcat/KM indicate that e-HBCD conversion was fastest and most specific with LinA2. Only one PBCDen stereoisomer was formed by LinA2, while LinA1 and LinATM produced mixtures of two PBCDE enantiomers at three times lower rates than LinA2. In analogy to the biotransformation of (−)β-HBCD, with selective conversion of dibromides in R-S-configuration, we assume that 1E,5S,6R,9S,10R-PBCDen is the e-HBCD transformation product from LinA2. Implementing three amino acids of the LinA1 substrate-binding site into LinA2 resulted in a triple mutant with similar kinetics and product specificity like LinA1. Thus, point-directed mutagenesis is an interesting tool to modify the substrate- and product-specificity of LinA enzymes and enlarge their scope to metabolize other halogenated persistent organic pollutants regulated under the Stockholm Convention.
- Published
- 2021
17. Bioethanol Blending Reduces Nanoparticle, PAH, and Alkyl- and Nitro-PAH Emissions and the Genotoxic Potential of Exhaust from a Gasoline Direct Injection Flex-Fuel Vehicle
- Author
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Jan Czerwinski, María Isabel Vera Muñoz, Pierre Comte, Peter Honegger, Kerstin Zeyer, Regula Haag, Norbert V. Heeb, and Joachim Mohn
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Engine power ,Particle number ,Waste management ,020209 energy ,02 engineering and technology ,General Chemistry ,010501 environmental sciences ,01 natural sciences ,Soot ,Biofuel ,E85 ,0202 electrical engineering, electronic engineering, information engineering ,Flexible-fuel vehicle ,Fuel efficiency ,Nanoparticles ,Environmental Chemistry ,Environmental science ,Polycyclic Aromatic Hydrocarbons ,Gasoline ,Gasoline direct injection ,Vehicle Emissions ,0105 earth and related environmental sciences - Abstract
Bioethanol as an alternative fuel is widely used as a substitute for gasoline and also in gasoline direct injection (GDI) vehicles, which are quickly replacing traditional port-fuel injection (PFI) vehicles. Better fuel efficiency and increased engine power are reported advantages of GDI vehicles. However, increased emissions of soot-like nanoparticles are also associated with GDI technology with yet unknown health impacts. In this study, we compare emissions of a flex-fuel Euro-5 GDI vehicle operated with gasoline (E0) and two ethanol/gasoline blends (E10 and E85) under transient and steady driving conditions and report effects on particle, polycyclic aromatic hydrocarbon (PAH), and alkyl- and nitro-PAH emissions and assess their genotoxic potential. Particle number emissions when operating the vehicle in the hWLTC (hot started worldwide harmonized light-duty vehicle test cycle) with E10 and E85 were lowered by 97 and 96% compared with that of E0. CO emissions dropped by 81 and 87%, while CO2 emissions w...
- Published
- 2016
18. Characterization of synthetic single-chain CP standard materials – Removal of interfering side products
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Marco Knobloch, Norbert V. Heeb, Walter Vetter, Peter Lienemann, Silvan Iten, Davide Bleiner, Jannik Sprengel, and Lena Schinkel
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Environmental Engineering ,Halogenation ,Health, Toxicology and Mutagenesis ,0208 environmental biotechnology ,02 engineering and technology ,Alkenes ,010501 environmental sciences ,01 natural sciences ,Gas Chromatography-Mass Spectrometry ,Mass Spectrometry ,Ion ,chemistry.chemical_compound ,Sulfite ,Impurity ,Alkanes ,Hydrocarbons, Chlorinated ,polycyclic compounds ,Environmental Chemistry ,0105 earth and related environmental sciences ,Chemical ionization ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,Sulfuryl chloride ,Pollution ,020801 environmental engineering ,Characterization (materials science) ,chemistry ,Paraffin ,Elemental analysis ,Mass spectrum ,Chlorine ,Nuclear chemistry - Abstract
The photolytic chlorination of n-alkanes in presence of sulfuryl chloride (SO2Cl2) was explored to produce new standard materials. Five mixtures of chlorinated tetradecanes were synthesized with chlorination degrees (mCl,EA) varying from 43.7% to 59.4% (m/m) based on elemental analysis. Chlorine-enhanced negative chemical ionization mass spectrometry (CE–NCI–MS) forcing the formation of chloride-adduct ions [M+Cl]- was applied to characterize these materials which all contained tetra-to deca-chlorinated paraffins. Deconvolution of respective mass spectra revealed the presence of chlorinated olefins (COs). CO levels were highest in materials, which were exposed longest. All synthesized materials also contained two classes of polar impurities, tentatively assigned as sulfite- and sulfate-diesters with molecular formulas of C14H28-xO3SClx (x = 1–4) and C14H28-xO4SClx (x = 3–6), respectively. MS data were in accordance with the proposed structures but further work is needed to deduce their constitutions. These compounds are thermolabile and were not detected with GC-MS methods. We could remove these sulfur-containing impurities from the CPs with normal-phase liquid chromatography. In conclusion, single-chain CP materials were synthesized via chlorination of n-alkanes with sulfuryl chloride, but these materials contained reactive side products which should be removed to gain non-reactive and stable CP materials suitable as standards and for fate and toxicity studies.
- Published
- 2020
19. Effects of Four Prototype Gasoline Particle Filters (GPFs) on Nanoparticle and Genotoxic PAH Emissions of a Gasoline Direct Injection (GDI) Vehicle
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Norbert V. Heeb, Pierre Comte, Joachim Mohn, Jan Czerwinski, María Isabel Vera Muñoz, Kerstin Zeyer, and Regula Haag
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020209 energy ,Nanoparticle ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,law.invention ,law ,0202 electrical engineering, electronic engineering, information engineering ,Environmental Chemistry ,Gasoline ,Gasoline direct injection ,Air quality index ,Filtration ,0105 earth and related environmental sciences ,Vehicle Emissions ,Air Pollutants ,General Chemistry ,Particulates ,Environmental chemistry ,Equivalent concentration ,Particle ,Environmental science ,Nanoparticles ,Particulate Matter ,DNA Damage - Abstract
The fast replacement of traditional gasoline port-fuel injection technology with gasoline direct-injection (GDI) vehicles is expected to have a substantial impact on urban air quality. Herein we report on effects of four prototype gasoline particle filters (GPFs) on exhausts of a 1.6 L Euro-5 GDI vehicle. Two noncoated and two filters with catalytic coatings were investigated. These filters, on average, lowered PN emissions 4–7-fold to 4.0–6.8 × 1011 particles/km. Genotoxic PAHs were lowered 2–5-fold too with GPF-1–3, with GPF-1 having the highest efficiency, 79% and resulting in 45 ng toxic equivalent concentration (TEQ)/km. Thus, particle filtration efficiencies and reduction of the genotoxic potentials are correlated. GPF-4 showing the poorest particle filtration efficiency (66–78%) also released exhausts with highest genotoxic potential of 240–530 ng TEQ/km. We recently reported particle-number (PN) emissions of four generations of GDI vehicles (Euro-3 to Euro-6) which released, on average, 2.5 × 1012...
- Published
- 2018
20. Catalytic diesel particulate filters reduce the in vitro estrogenic activity of diesel exhaust
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Renato Zenobi, Norbert V. Heeb, Andreas C. Gerecke, Hanspeter Naegeli, Daniela Wenger, and University of Zurich
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Diesel particulate filter ,Diesel exhaust ,1303 Biochemistry ,Gene Expression ,Estrogen receptor ,Estrogenic activity ,Diesel engine ,Biochemistry ,complex mixtures ,Catalysis ,Analytical Chemistry ,Genes, Reporter ,Cell Line, Tumor ,Humans ,CALUX ,In vitro reporter gene assay ,Vehicle Emissions ,Reporter gene ,1602 Analytical Chemistry ,Chromatography ,Dose-Response Relationship, Drug ,Chemistry ,Estrogen Antagonists ,Reproducibility of Results ,Estrogens ,10079 Institute of Veterinary Pharmacology and Toxicology ,In vitro ,Diesel particles ,Receptors, Estrogen ,570 Life sciences ,biology ,Biological Assay ,Particulate Matter ,human activities ,Filtration - Abstract
Analytical and Bioanalytical Chemistry, 390 (8), ISSN:1618-2650, ISSN:1618-2642
- Published
- 2018
21. PN-Emissions of Gasoline Cars MPI and Potentials of GPF
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Peter Bonsack, Danilo Engelmann, Norbert V. Heeb, Pierre Comte, María Isabel Vera Muñoz, Volker Hensel, Jan Czerwinski, and Andreas Mayer
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020303 mechanical engineering & transports ,0203 mechanical engineering ,020209 energy ,0202 electrical engineering, electronic engineering, information engineering ,Environmental science ,02 engineering and technology ,Gasoline ,Automotive engineering - Published
- 2018
22. Analysis of medium-chain and long-chain chlorinated paraffins: the urgent need for more specific analytical standards
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Davide Bleiner, Lena Schinkel, Kristopher McNeill, Norbert V. Heeb, Christian Bogdal, Ronan Cariou, Elia Canonica, Swiss Federal Laboratories for Materials Science and Technology (EMPA), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Zürich University of Applied Sciences (ZHAW), Laboratoire d'étude des Résidus et Contaminants dans les Aliments (LABERCA), Ecole Nationale Vétérinaire, Agroalimentaire et de l'alimentation Nantes-Atlantique (ONIRIS)-Institut National de la Recherche Agronomique (INRA), and Swiss Federal Office for the Environment (BAFU, Switzerland)
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High production volume chemicals ,endocrine system ,resolution mass-spectrometry ,Health, Toxicology and Mutagenesis ,[SDV]Life Sciences [q-bio] ,010501 environmental sciences ,deconvolution ,01 natural sciences ,environmental matrices ,temporal trends ,Chlorinated paraffins ,Chain (algebraic topology) ,polycyclic compounds ,Environmental Chemistry ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Water Science and Technology ,Pollutant ,Ecology ,transformation ,010401 analytical chemistry ,toxicity ,Pollution ,quantification ,0104 chemical sciences ,mixtures ,13. Climate action ,Environmental chemistry ,interferences ,Environmental science ,lipids (amino acids, peptides, and proteins) ,n-alkanes ,Long chain - Abstract
International audience; Chlorinated paraffins (CPs) are high production volume chemicals and ubiquitous environmental pollutants. In particular, data about the environmental fate of medium-chain (MCCPs, C14-C17) and long-chain (LCCPs, C->= 18) CPs are urgently needed. Their analysis requires elaborate analytical methods and representative analytical standards. Complex mixtures that contain CPs of different carbon chain lengths and degrees of chlorination are currently used for quantification but are impractical when chain length distributions substantially differ between samples and standards. Single-chain CP mixtures of only one carbon chain length but varying degrees of chlorination are more suitable for accurate quantification but are not available for MCCPs and LCCPs. Such standards are useful for homologue pattern deconvolution and response factor calculations. Toxicity and transformation studies on MCCPs and LCCPs are scarce. Respective studies would also benefit from less complex CP standards, e.g., single-chain mixtures or even constitutionally defined CPs. Currently available analytical standards are inadequate for the demanding task of quantifying MCCPs and LCCPs. Improved standards are required. This review provides an overview of the available analytical CP materials, discusses their advantages and disadvantages for accurate CP analysis, and gives a recommendation for improvements. Recommendations for improved analytical standards include (A) complex CP mixtures that better resemble technical CP mixtures, (B) single-chain CP mixtures of different carbon chain lengths (C-10-C-30) and varying degrees of chlorination (40-70 wt%Cl), (C) constitutionally defined CPs with representative chlorination patterns, and (D) isotopically labeled CP isomers that represent a broad range of CPs.
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- 2018
23. Dealing with strong mass interferences of chlorinated paraffins and their transformation products: An analytical guide
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Christian Bogdal, Ronan Cariou, Sandro Lehner, Kristopher McNeill, Philippe Marchand, Norbert V. Heeb, Lena Schinkel, Eidgenössische Materialprüfungs und Forschungsanstalt - Swiss Federal Laboratories for Materials Science and Technology, Partenaires INRAE, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Zürich University of Applied Sciences (ZHAW), Laboratoire d'étude des Résidus et Contaminants dans les Aliments (LABERCA), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Vétérinaire, Agroalimentaire et de l'alimentation Nantes-Atlantique (ONIRIS), and Swiss Federal Office for the Environment (BAFU) [15.0021.PJ/O113-2203 V]
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Degradation kinetics ,[SDV]Life Sciences [q-bio] ,010501 environmental sciences ,Mass spectrometry ,01 natural sciences ,Analytical Chemistry ,Transformation ,Degradation ,Chlorinated paraffins ,Computational chemistry ,Selected ion monitoring ,In-source fragmentation ,Persistent organic pollutants (POPs) ,Spectroscopy ,Chlorinated olefins (COs) ,0105 earth and related environmental sciences ,Alternative methods ,Chemistry ,010401 analytical chemistry ,Mass interferences ,0104 chemical sciences ,Transformation (function) ,Chlorinated paraffins (CPs) ,Gas chromatography ,Soft ionisation - Abstract
International audience; Chlorinated paraffins (CPs) are high production volume chemicals. Their analysis is demanding and becomes even more challenging in presence of CP transformation products. Chlorinated olefins (COs) are expected thermal CP transformation products that are present in technical CP products and in the environment. Thus, a specific analysis of CPs and COs is important. Commonly, CPs are analysed by gas chromatography electron capture negative ionisation mass spectrometry (GC-ECNI-MS). It was shown that GC-ECNI-MS suffers from in-source formation of COs. Further, selected ion monitoring can lead to false quantification of COs as CPs. Alternative methods based on liquid chromatography and soft ionisation techniques can solve the CP/CO problem. Non-interfered CP data is inevitable for CP transformation studies and non-biased degradation kinetics. Data about CP transformation is urgently needed, but respective studies are challenging. In here, we provided an analytical guide to deal with severe mass interferences of CPs and their transformation products. (C) 2018 Elsevier B.V. All rights reserved.
- Published
- 2018
24. Stereochemistry of enzymatic transformations of (+)β- and (−)β-HBCD with LinA2 – A HCH-degrading bacterial enzyme of Sphingobium indicum B90A
- Author
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Birgit Geueke, Peter Lienemann, Heidi Moor, Thomas Fleischmann, W. Bernd Schweizer, Simon A. Wyss, Hans-Peter E. Kohler, and Norbert V. Heeb
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Environmental Engineering ,Stereochemistry ,Health, Toxicology and Mutagenesis ,Metabolite ,Molecular Conformation ,Stereoisomerism ,Catalysis ,chemistry.chemical_compound ,Bacterial Proteins ,Environmental Chemistry ,biology ,Public Health, Environmental and Occupational Health ,Cationic polymerization ,General Medicine ,General Chemistry ,biology.organism_classification ,Pollution ,Hydrocarbons, Brominated ,Sphingomonadaceae ,chemistry ,Docking (molecular) ,Enantiomer ,Hexachlorocyclohexane ,Sphingobium indicum - Abstract
LinA2, a bacterial enzyme expressed in various Sphingomonadaceae, catalyzes the elimination of HCl from hexachlorocyclohexanes (HCHs) and, as discussed here, the release of HBr from certain hexabromocyclododecanes (HBCDs). Both classes of compounds are persistent organic pollutants now regulated under the Stockholm Convention. LinA2 selectively catalyzes the transformation of β-HBCDs; other stereoisomers like α-, γ-, and δ-HBCDs are not converted. The transformation of (-)β-HBCD is considerably faster than that of its enantiomer. Here, we present the XRD crystal structure of 1E,5S,6S,9R,10S-pentabromocyclododecene (PBCDE) and demonstrate that its enantiomer with the 1E,5R,6R,9S,10R-configuration is the only metabolite formed during LinA2-catalyzed dehydrobromination of (-)β-HBCD. Formation of this product can be rationalized by HBr elimination at C5 and C6. A reasonable enzyme-substrate complex with the catalytic dyad His-73 and Asp-25 approaching the hydrogen at C6 and a cationic pocket of Lys-20, Try-42 and Arg-129 binding the leaving bromine at C5 was found from in silico docking experiments. A second PBCDE of yet unknown configuration was obtained from (+)β-HBCD. We predicted its stereochemistry to be 1E,5S,6S,9S,10R-PBCDE from docking experiments. The enzyme-substrate complex obtained from LinA2 and an activated conformation of (+)β-HBCD allows the HBr elimination at C9 and C10 leading to the predicted product. Both modeled enzyme-substrate complexes are in line with 1,2-diaxial HBr eliminations. In conclusion, LinA2, a bacterial enzyme of the HCH-degrading strain Sphingobium indicum B90A was able to stereoselectively convert β-HBCDs. Configurations of both PBCDE metabolites were predicted by molecular docking experiments and confirmed in one case by XRD data.
- Published
- 2015
25. Gas phase composition and secondary organic aerosol formation from gasoline direct injection vehicles investigated in batch and flow reactors: effects of prototype gasoline particle filters
- Author
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Jay G. Slowik, Urs Baltensperger, Josef Dommen, Emily A. Bruns, Nivedita K. Kumar, Jan Czerwinski, André S. H. Prévôt, Deepika Bhattu, Norbert V. Heeb, Simone M. Pieber, Imad El Haddad, Pierre Comte, Dogushan Kilic, Felix Klein, and Alejandro Keller
- Subjects
Cold start (automotive) ,010504 meteorology & atmospheric sciences ,Chemistry ,Xylene ,Particulates ,01 natural sciences ,Toluene ,Aerosol ,chemistry.chemical_compound ,Environmental chemistry ,Aerosol mass spectrometry ,Gasoline ,Gasoline direct injection ,0105 earth and related environmental sciences - Abstract
Gasoline direct injection (GDI) vehicles have recently been identified as a significant source of carbonaceous aerosol, of both primary and secondary origin. Here we investigated primary emissions and secondary organic aerosol (SOA) formation from GDI vehicle exhaust for multiple vehicles and driving test cycles, and novel GDI after-treatment systems. Emissions were characterized by proton transfer reaction time-of-flight mass spectrometry (gaseous non-methane organic compounds, NMOCs), aerosol mass spectrometry (sub-micron non-refractory particles), and light attenuation measurements (equivalent black carbon (eBC) determination using Aethalometer measurements) together with supporting instrumentation. We evaluated the effect of retrofitted prototype gasoline particle filters (GPFs) on primary eBC, organic aerosol (OA), NMOCs, as well as SOA formation. Two regulatory driving test cycles were investigated, and the importance of distinct phases within these cycles (e.g. cold engine start, hot engine start, high speed driving) to primary emissions and secondary products was evaluated. Atmospheric processing was simulated using both the PSI mobile smog chamber (SC) and the potential aerosol mass oxidation flow reactor (OFR). GPF retrofitting was found to greatly decrease primary particulate matter (PM) through removal of eBC, but showed limited partial removal of the minor POA fraction, and had no detectable effect on either NMOC emissions (absolute emission factors or relative composition) or SOA production. In all tests, overall primary and secondary PM and NMOC emissions were dominated by the engine cold start, i.e. before thermal activation of the catalytic after-treatment system. Differences were found in the bulk compositional properties of SOA produced by the OFR and the SC (O : C and H : C ratios), while the SOA yields agree within our uncertainties, with a tendency for lower SOA yields in SC experiments. A few aromatic compounds are found to dominate the NMOC emissions (primarily benzene, toluene, xylene isomers and C3-benzenes). A large fraction (> 0.5) of the SOA production was explained by those compounds, based on investigation of reacted NMOC mass and comparison with SOA yield curves of toluene, o-xylene and 1,2,4-trimethylbenzene determined in our OFR within this study. Remaining differences in the obtained SOA yields may result from diverse reasons including aging conditions, unaccounted-for precursors and differences in SOA yields of aromatic hydrocarbons with different degrees of substitution, as well as experimental uncertainties in the assessment of particle and vapor wall losses.
- Published
- 2017
26. Transformation of chlorinated paraffins to olefins during metal work and thermal exposure - Deconvolution of mass spectra and kinetics
- Author
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Marco Knobloch, Norbert V. Heeb, Sandro Lehner, Peter Lienemann, Lena Schinkel, Kristopher McNeill, and Christian Bogdal
- Subjects
Environmental Engineering ,Hot Temperature ,Health, Toxicology and Mutagenesis ,Kinetics ,Inorganic chemistry ,Hydrochloric acid ,010501 environmental sciences ,Alkenes ,Mass spectrometry ,complex mixtures ,01 natural sciences ,Mass Spectrometry ,Metal ,chemistry.chemical_compound ,stomatognathic system ,Chlorinated paraffins ,Hydrocarbons, Chlorinated ,Environmental Chemistry ,Selected ion monitoring ,0105 earth and related environmental sciences ,010401 analytical chemistry ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,Pollution ,0104 chemical sciences ,carbohydrates (lipids) ,stomatognathic diseases ,chemistry ,Paraffin ,visual_art ,Metallurgy ,Mass spectrum ,visual_art.visual_art_medium ,Degradation (geology) ,Environmental Monitoring - Abstract
Chlorinated paraffins (CPs) are high production volume chemicals widely used as additives in metal working fluids. Thereby, CPs are exposed to hot metal surfaces which may induce degradation processes. We hypothesized that the elimination of hydrochloric acid would transform CPs into chlorinated olefins (COs). Mass spectrometry is widely used to detect CPs, mostly in the selected ion monitoring mode (SIM) evaluating 2-3 ions at mass resolutions R 20'000. This approach is not suited to detected COs, because their mass spectra strongly overlap with CPs. We applied a mathematical deconvolution method based on full-scan MS data to separate interfered CP/CO spectra. Metal drilling indeed induced HCl-losses. CO proportions in exposed mixtures of chlorotridecanes increased. Thermal exposure of chlorotridecanes at 160, 180, 200 and 220 °C also induced dehydrohalogenation reactions and CO proportions also increased. Deconvolution of respective mass spectra is needed to study the CP transformation kinetics without bias from CO interferences. Apparent first-order rate constants (k
- Published
- 2017
27. Nanoparticle Emissions of DI Gasoline Cars with/without GPF
- Author
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Jan Czerwinski, Norbert V. Heeb, Volker Hensel, Pierre Comte, and Andreas Mayer
- Subjects
020303 mechanical engineering & transports ,0203 mechanical engineering ,Chemical engineering ,Nanoparticle ,Environmental science ,02 engineering and technology ,010501 environmental sciences ,Gasoline ,01 natural sciences ,0105 earth and related environmental sciences - Published
- 2017
28. Optimising ‘Moments of Pauses’ – A Reflections from COVID-19 Pandemic
- Author
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Jan Czerwinski, Norbert V. Heeb, and Andreas Mayer
- Subjects
History ,Coronavirus disease 2019 (COVID-19) ,Development economics ,Pandemic - Published
- 2014
29. LinA2, a HCH-converting bacterial enzyme that dehydrohalogenates HBCDs
- Author
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Birgit Geueke, Thomas Fleischmann, Peter Lienemann, Hans-Peter E. Kohler, Norbert V. Heeb, and Simon A. Wyss
- Subjects
HCH-converting bacterial enzyme ,Environmental Engineering ,Halogenation ,Hydrolases ,Stereochemistry ,Health, Toxicology and Mutagenesis ,Stereoisomerism ,HBCD biotransformation ,Brominated flame retardants ,Environmental Chemistry ,Enantiomeric excess ,Biotransformation ,LinA2 metabolites ,Dehalogenase ,572: Biochemie ,Meso compound ,Chemistry ,Persistent organic pollutants ,Public Health, Environmental and Occupational Health ,Substrate (chemistry) ,Lindane ,Soil pollutants ,General Medicine ,General Chemistry ,Brominated hydrocarbons ,Pollution ,Hydrocarbons, Brominated ,Sphingomonadaceae ,Kinetics ,Biocatalysis ,Polystyrenes ,Hexachlorocyclohexane ,Haloalkane dehalogenase ,Sphingobium indicum - Abstract
Hexabromocyclododecanes (HBCDs) and hexachlorocyclohexanes (HCHs) are lipophilic, polyhalogenated hydrocarbons with comparable stereochemistry. Bacterial evolution in HCH-contaminated soils resulted in the development of several Spingomonadaceae which express a series of HCH-converting enzymes. We showed that LinB, a haloalkane dehalogenase from Sphingobium indicum B90A, also transforms various HBCDs besides HCHs. Here we present evidence that LinA2, another dehalogenase from S. indicum also converts certain HBCDs to pentabromocyclododecenes (PBCDEs). Racemic mixtures of α-, β-, γ-HBCDs, a mixture of them, and δ-HBCD, a meso form, were exposed to LinA2. Substantial conversion of (-)β-HBCD was observed, but all other stereoisomers were not transformed significantly. The enantiomeric excess (EE) of β-HBCDs increased up to 60% in 32 h, whereas EE values of α- and γ-HBCDs were not affected. Substrate conversion and product formation were described with second-order kinetic models. One major (P1β) and possibly two minor (P2β, P3β) metabolites were detected. Respective mass spectra showed the characteristic isotope pattern of PBCDEs, the HBr elimination products of HBCDs. Michaelis-Menten parameters KM=0.47 ± 0.07 μM and vmax=0.17 ± 0.01 μmoll(-1)h(-1) were deduced from exposure data with varying enzyme/substrate ratios. LinA2 is more substrate specific than LinB, the latter converted all tested HBCDs, LinA2 only one. The widespread HCH pollution favored the selection and evolution of bacteria converting these compounds. We found that LinA2 and LinB, two of these HCH-converting enzymes expressed in S. indicum B90A, also dehalogenate HBCDs to lower brominated compounds, indicating that structural similarities of both classes of compounds are recognized at the level of substrate-protein interactions.
- Published
- 2014
30. Effects of an iron-based fuel-borne catalyst and a diesel particle filter on exhaust toxicity in lung cells in vitro
- Author
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Barbara Rothen-Rutishauser, Alke Petri-Fink, Andreas Mayer, Norbert V. Heeb, Pierre Comte, Sandro Steiner, and Jan Czerwinski
- Subjects
Diesel exhaust ,Cell Survival ,Iron ,medicine.disease_cause ,Combustion ,complex mixtures ,Biochemistry ,Catalysis ,Cell Line ,Analytical Chemistry ,Diesel fuel ,medicine ,Humans ,Diesel exhaust fluid ,Lung ,Vehicle Emissions ,Air filter ,Inflammation ,Mutagenicity Tests ,Chemistry ,Environmental Exposure ,Pulp and paper industry ,Soot ,Oxidative Stress ,Air Filters ,Toxicity ,human activities ,Sulfur ,Mutagens - Abstract
Metal-containing fuel additives catalyzing soot combustion in diesel particle filters are used in a widespread manner, and with the growing popularity of diesel vehicles, their application is expected to increase in the near future. Detailed investigation into how such additives affect exhaust toxicity is therefore necessary and has to be performed before epidemiological evidence points towards adverse effects of their application. The present study investigates how the addition of an iron-based fuel additive (Satacen®3, 40 ppm Fe) to low-sulfur diesel affects the in vitro cytotoxic, oxidative, (pro-)inflammatory, and mutagenic activity of the exhaust of a passenger car operated under constant, low-load conditions by exposing a three-dimensional model of the human airway epithelium to complete exhaust at the air-liquid interface. We could show that the use of the iron catalyst without and with filter technology has positive as well as negative effects on exhaust toxicity compared to exhaust with no additives: it decreases the oxidative and, compared to a non-catalyzed diesel particle filter, the mutagenic potential of diesel exhaust, but increases (pro-)inflammatory effects. The presence of a diesel particle filter also influences the impact of Satacen®3 on exhaust toxicity, and the proper choice of the filter type to be used is of importance with regards to exhaust toxicity. Figure ᅟ.
- Published
- 2014
31. Biotransformation of hexabromocyclododecanes with hexachlorocyclohexane-transforming Sphingobium chinhatense strain IP26
- Author
-
Peter Lienemann, Andreas Grubelnik, Birgit Geueke, Norbert V. Heeb, and Hans-Peter E. Kohler
- Subjects
0301 basic medicine ,Environmental Engineering ,Halogenation ,Health, Toxicology and Mutagenesis ,Hexachlorocyclohexane ,010501 environmental sciences ,01 natural sciences ,03 medical and health sciences ,chemistry.chemical_compound ,Bioremediation ,Biotransformation ,Environmental Chemistry ,Enantiomeric excess ,0105 earth and related environmental sciences ,Flame Retardants ,biology ,Public Health, Environmental and Occupational Health ,Stereoisomerism ,General Medicine ,General Chemistry ,Pesticide ,biology.organism_classification ,Pollution ,Hydrocarbons, Brominated ,Sphingomonadaceae ,Transformation (genetics) ,030104 developmental biology ,Biodegradation, Environmental ,chemistry ,Environmental chemistry ,Environmental Pollutants ,Enantiomer ,Bacteria - Abstract
Bacterial evolution has resulted in the appearance of several Sphingomonadacea strains that gained the ability to metabolize hexachlorocyclohexanes (HCHs). HCHs have been widely used as pesticides but were banned under the Stockholm Convention on persistent organic pollutants (POPs) in 2009. Here we present evidence for bacterial transformation reactions of hexabromocyclododecanes (HBCDs), which are structurally related to HCHs. HBCDs were used as flame retardants. They are now also considered as POPs and their production and use is restricted since 2013. Racemic α-, β-, and γ-HBCDs and their mixture were exposed to Sphingobium chinhatense IP26 in resting cell assays in parallel to β-HCH. All HBCD stereoisomers were converted with (−)β-HBCD being the best and both α-HBCD enantiomers the poorest substrates. HBCD conversion rates were 27–430 times slower than that of β-HCH. Three generations of hydroxylated transformation products were observed, 7 pentabromocyclododecanol isomers (PeBCD-ols), 11 tetrabromocyclododecadiols (TeBCD-diols) and 3 tribromocyclododecatriols (TrBCD-triols). The conversion of (+)α-, (−)β- and (−)γ-HBCD was faster than those of their enantiomers. Therefore the respective enantiomeric excess increased to 3 ± 1%, 36 ± 1% and 6 ± 2% during 48 h of bacterial exposure. PeBCD-ols appeared first, followed by TeBCD-diols and TrBCD-triols indicating stepwise hydrolytic dehalogenation reactions. In conclusion, severe HCH pollution at geographically distinct dumpsites triggered bacterial evolution to express enzymes transforming such compounds. We used S. chinhatense IP26 bacteria to transform structurally related HBCDs, also regulated under the Stockholm Convention. Such bacteria might be useful for bioremediation but the toxicity of the numerous transformation products observed must be assessed in advance.
- Published
- 2016
32. Mass Spectrometric Analysis of Short-chain Chlorinated Paraffins in Plastic Consumer Products
- Author
-
Lena Schinkel, Norbert V. Heeb, Davide Bleiner, Peter Lienemann, and Elia Canonica
- Subjects
Chromatography ,Chlorinated paraffins ,Chain (algebraic topology) ,Chemistry ,General Medicine ,General Chemistry ,Mass spectrometric - Published
- 2019
33. Crystal structure of δ-isobutoxypentabromo-cyclododecanes, kinetics and selectivity of their isomerization during thermal treatment of flame-proofed polystyrenes
- Author
-
Peter Lienemann, Norbert V. Heeb, Meret Heeb, W. Bernd Schweizer, and Heidi Graf
- Subjects
Environmental Engineering ,Health, Toxicology and Mutagenesis ,Crystal structure ,Thermal treatment ,Heating ,chemistry.chemical_compound ,Reaction rate constant ,Isomerism ,Environmental Chemistry ,Organic chemistry ,Flame Retardants ,Hexabromocyclododecane ,Public Health, Environmental and Occupational Health ,Diastereomer ,General Medicine ,General Chemistry ,Pollution ,Hydrocarbons, Brominated ,Kinetics ,Crystallography ,chemistry ,Polystyrenes ,Enantiomer ,Crystallization ,Selectivity ,Isomerization - Abstract
Hexabromocyclododecanes (HBCDs) are persistent organic pollutants now ubiquitous in the environment. Technical HBCD mixtures and with it flame-proofed polystyrenes (FP-PS) also contain isobutoxypentabromocyclododecanes (iBPBCDs) as minor constituents, which are possibly released together with HBCDs. So far, eight diastereomeric pairs of enantiomers named as alpha-, beta-, gamma-, delta-, epsilon-, xi-, eta-, and theta-iBPBCDs with proportions of 10%, 5%, 2%, 21%, 11%, 11%, 12% and 28% were found in technical HBCD. Herein the crystal structure of racemic delta-iBPBCD, the second most prominent diastereomer, is presented and assigned to (1S)-1-isobutoxy-(2R,5R,6S,9S,10S)-2,5,6,9,10-pentabromocyclododecane and its enantiomer. During thermal treatment of FP-PS, e.g. the production of extruded polystyrenes (XPS), proportions of delta-iBPBCDs decrease and those of other stereoisomers increase. Evidence was found that delta-iBPBCDs isomerize stereo- and regioselectively to beta-iBPBCDs. Based on structural and kinetic data, a transformation mechanism was proposed. Apparent first-order rate constants (k(iso)) of 0.0019, 0.0050, and 0.012 min(-1) are found for the delta- to beta-iBPBCD isomerization at 120, 130, and 140 degrees C, respectively, corresponding to half-lives of 360, 140, and 56 min. These transformations also occur during the production of XPS, which predominantly contain beta-iBPBCDs, whereas delta-iBPBCDs dominate in materials experiencing lower thermal stress, e.g. expanded polystyrenes (EPS). The relative configurations of delta- and theta-iBPBCDs are TtCtCt, like the one of gamma-HBCDs. gamma-HBCDs are the kinetically and alpha-HBCDs with a TcCtCc configuration the thermodynamically favored products. In analogy, beta-iBPBCDs are assumed to have a TcCtCc configuration like alpha-HBCDs because they are formed from delta-iBPBCDs under thermodynamic control. In conclusion, HBCD- and iBPBCD-patterns in flame-proofed polystyrenes vary substantially, reflecting the thermal stress these materials have experienced. When released to the environment, these patterns might further change, as observed for HBCDs.
- Published
- 2011
34. Reactive nitrogen compounds (RNCs) in exhaust of advanced PM–NOx abatement technologies for future diesel applications
- Author
-
Peter Schmid, Yan Zimmerli, Adrian Wichser, Norbert V. Heeb, Markus Zennegg, Andreas Mayer, Lukas Emmenegger, Cornelia Seiler, Markus Kasper, Kerstin Zeyer, Peter Honegger, Andrea Ulrich, Thomas Mosimann, Regula Haag, and Jan Czerwinski
- Subjects
Atmospheric Science ,Diesel particulate filter ,Waste management ,Selective catalytic reduction ,Isocyanic acid ,Diesel engine ,chemistry.chemical_compound ,Diesel fuel ,Ammonia ,chemistry ,Environmental chemistry ,Nitrogen dioxide ,NOx ,General Environmental Science - Abstract
Long-term exposure to increased levels of reactive nitrogen compounds (RNCs) and particulate matter (PM) affect human health. Many cities are currently not able to fulfill European air quality standards for these critical pollutants. Meanwhile, promising new abatement technologies such as diesel particle filters (DPFs) and selective catalytic reduction (SCR) catalysts are developed to reduce PM and RNC emissions. Herein, effects of a urea-based SCR system on RNC emissions are discussed and we quantified the highly reactive intermediates isocyanic acid (HNCO) and ammonia (NH 3 ), both potential secondary pollutants of the urea-based SCR chemistry. A diesel engine (3.0 L, 100 kW), operated in the ISO 8178/4 C1, cycle was used as test platform. A V 2 O 5 -based SCR catalyst was either applied as such or down-stream of a high oxidation potential-DPF (hox-DPF). With active SCR, nitric oxide (NO) and nitrogen dioxide (NO 2 ) conversion efficiencies of 0.86–0.94 and 0.86–0.99 were obtained. On the other hand, mean HNCO and NH 3 emissions increased to 240–280 and 1800–1900 mg h −1 . On a molar basis, HNCO accounted for 0.8–1.4% and NH 3 for 14–25% of the emitted RNCs. On roads, SCR systems will partly be inactive when exhaust temperatures drop below 220 °C. The system was active only during 75% of the test cycle, and urea dosing was stopped and restarted several times. Consequently, NO conversion stopped but interestingly, NO 2 was still converted. Such light-off and shutdown events are frequent in urban driving, compromising the overall deNO x efficiency. Another important effect of the SCR technology is illustrated by the NH 3 /NO 2 ratio, which was >1 with active SCR, indicating that exhaust is basic rather than acidic after the SCR catalyst. Under these conditions, isocyanic acid is stable. The widespread use of various converter technologies already affected RNC release. Diesel oxidation catalysts (DOCs) and hox-DPFs increased NO 2 emissions, three-way catalysts (TWCs) those of NH 3 . The investigated SCR technology substantially lowered NO and NO 2 emissions, while NH 3 levels were comparable to those of TWC vehicles (300–1500 mg h −1 ). If applied in the future, the combined DPF/SCR technology will change ambient RNC levels, PM compositions and atmospheric redox- and acid/base-chemistry in traffic-affected areas.
- Published
- 2011
35. Unregulated Emissions with TWC, Gasoline & amp; CNG
- Author
-
Yan Zimmerli, Norbert V. Heeb, Thomas Hilfiker, Christian Bach, Jan Czerwinski, and Anna-Maria Forss
- Subjects
Waste management ,Environmental science ,General Medicine ,Gasoline - Published
- 2010
36. Aryl hydrocarbon receptor-mediated activity of atmospheric particulate matter from an urban and a rural site in Switzerland
- Author
-
Cornelia Seiler, Regula Haag, Daniela Wenger, Andreas C. Gerecke, Hanspeter Naegeli, Renato Zenobi, Norbert V. Heeb, and Christoph Hueglin
- Subjects
Fluoranthene ,chemistry.chemical_classification ,Atmospheric Science ,Persistent organic pollutant ,biology ,Chemistry ,Context (language use) ,Particulates ,Aryl hydrocarbon receptor ,chemistry.chemical_compound ,Hydrocarbon ,Environmental chemistry ,biology.protein ,CALUX ,Carcinogen ,General Environmental Science - Abstract
Atmospheric particulate matter (PM) is an air-suspended mixture of solid and liquid particles that vary in size, shape, and chemical composition. Long-term exposure to elevated concentrations of fine atmospheric particles is considered to pose a health threat to humans and animals. In this context, it has been hypothesized that toxic chemicals such as polycyclic aromatic hydrocarbons (PAHs) play an important role. Some PAHs are known to be carcinogenic and it has been shown that carcinogenic effects of PAHs are mediated by the aryl hydrocarbon receptor (AhR). In this study, PM1 was collected at a rural and an urban traffic site during an intense winter smog period, in which concentration of PM1 often exceeded 50 μg m−3. We applied an in vitro reporter gene assay (DR-CALUX) to detect and quantify PM1-associated chemicals that induce AhR-mediated gene expression. This activity was expressed as CALUX equivalents of 2,3,7,8-tetrachlorodibenzodioxin (PM-TCDD-CEQs). In addition, concentrations of PAHs in the PM1 extracts were determined using gas chromatography/high-resolution mass spectrometry. Concentrations of PM-TCDD-CEQs ranged from 10 to 85 pg m−3 and from 19 to 87 pg m−3 at the urban and rural site, respectively. By the use of known relative potency factors, the measured concentration of a PAH was converted into a PAH-TCDD-CEQ concentration. ΣPAH-TCDD-CEQ and PM-TCDD-CEQ were highly correlated at both sites (r2 = 0.90 and 0.69). The calculated ΣPAH-TCDD-CEQs explain between 2% and 20% of the measured PM-TCDD-CEQs. Benzo[k]fluoranthene was the most important PAH causing approximately 60% of the total ΣPAH-TCDD-CEQ activity. In contrast to NO, CO, PM10, and PM1, the concentration of PM-TCDD-CEQs showed no significant difference between the two sites. No indications were found that road traffic emissions caused elevated concentrations of PM-TCDD-CEQs at the urban traffic site.
- Published
- 2009
37. In vitroestrogenicity of ambient particulate matter: contribution of hydroxylated polycyclic aromatic hydrocarbons
- Author
-
Peter Schmid, Norbert V. Heeb, Andreas C. Gerecke, Daniela Wenger, Renato Zenobi, Christoph Hueglin, and Hanspeter Naegeli
- Subjects
Rural Population ,Urban Population ,Air pollution ,Estrogen receptor ,Breast Neoplasms ,Hydroxylation ,Toxicology ,medicine.disease_cause ,Air pollution episode ,Genes, Reporter ,Cell Line, Tumor ,medicine ,Humans ,CALUX ,Particle Size ,Polycyclic Aromatic Hydrocarbons ,Luciferases ,Carcinogen ,Retrospective Studies ,Air Pollutants ,Dose-Response Relationship, Drug ,Molecular Structure ,Chemistry ,Estrogen Antagonists ,Estrogens ,Biological activity ,Particulates ,Receptors, Estrogen ,Endocrine disruptor ,Environmental chemistry ,Female ,Particulate Matter ,Switzerland ,Environmental Monitoring - Abstract
Atmospheric particulate matter (PM1) was collected at an urban and a rural site in Switzerland during a hibernal high air pollution episode and was investigated for estrogenicity using an estrogen-sensitive reporter gene assay (ER-CALUX). All samples that were tested induced estrogen receptor-mediated gene expression in T47D human breast adenocarcinoma cells. Observed estrogenic activities corresponded to 17beta-estradiol (E2) CALUX equivalent concentrations ranging from 2 to 23 ng E2-CEQ per gram of PM1 (particulate matter ofor = 1 microm aerodynamic diameter) and from 0.07 to 1.25 pg E2-CEQ per m(3) of sampled air. There was a strong correlation between the PM1 estrogenicity of the urban and rural sites (r = 0.92). Five hydroxylated polycyclic aromatic hydrocarbons (hydroxy-PAHs), which show structural similarities to E2, were assessed for their estrogenic activity. The following order of estrogenic potency was found: 2-hydroxychrysene2-hydroxyphenanthrene1-hydroxypyrene2-hydroxynaphthalene1-hydroxynaphthalene. Three of these hydroxy-PAHs, namely 2-hydroxyphenanthrene, 2-hydroxynaphthalene and 1-hydroxynaphthalene, were detected in all PM1 extracts. However, they contributed only 0.01-0.2% to the overall estrogenic activity. Hence, mainly other estrogenic compounds not yet identified by chemical analysis must be responsible for the observed activity. The temporal trend of PM1 estrogenicity at the urban and rural site, respectively, was compared with the time course of several air pollutants (NO2, NO, SO2, O3, CO) and meteorological parameters (temperature, humidity, air pressure, solar irradiation, wind velocity). However, specific emission sources and formation processes of atmospheric xenoestrogens could not be elucidated. This study showed that ambient particulate matter contains compounds that are able to interact with estrogen receptors in vitro and potentially also interfere with estrogen-regulated pathways in vivo.
- Published
- 2009
38. Quality Standards and Test Procedures for Particle Filters to Retrofit Utility Vehicles
- Author
-
Gerhard Leutert, Andreas Mayer, Francois Jaussi, Markus Kasper, Andrea Ulrich, Norbert V. Heeb, and Jan Czerwinski
- Subjects
Scheme (programming language) ,Engineering ,business.industry ,media_common.quotation_subject ,General Medicine ,Reliability engineering ,Test (assessment) ,Diesel fuel ,Software deployment ,Retrofitting ,Quality (business) ,Test particle ,business ,Particle filter ,computer ,computer.programming_language ,media_common - Abstract
A new approach is needed to test particle filters for retrofitting Diesel engines. Considering the toxicity of the particles as also the physical and chemical attributes of particle filters, the optimal scheme is to test the components themselves independent of the deployment. That scheme ensures the highest effectiveness with least effort. It also enables evaluation of worst-case situations and assesses the hazards of secondary emissions. The Swiss standard SNR 277 205, which mandates the VERT test procedure, is a first step in that direction.
- Published
- 2009
39. Qualitätsstandards und Prüfverfahren für Partikelfilter zur Nachrüstung von Nutzfahrzeugen
- Author
-
Andrea Ulrich, Gerhard Leutert, Norbert V. Heeb, Francois Jaussi, Andreas Mayer, Markus Kasper, and Jan Czerwinski
- Subjects
Physics ,Automotive Engineering ,Humanities - Abstract
Zur Prufung von Partikelfiltern fur die Nachrustung von Dieselmotoren mussen neue Wege beschritten werden. Unter Berucksichtigung der gesundheitlichen Wirkungen der Partikel sowie der physikalischen und chemischen Eigenschaften von Partikelfiltern ergibt sich als optimale Losung die Prufung der Komponente selbst, getrennt von der Anwendung. Das gewahrleistet hochste Effizienz bei geringstem Aufwand und gestattet, Worst-case-Situationen und die Bildung von Sekundaremissionen mit zu berucksichtigen. Mit der Schweizerischen Norm SNR 277 205, die das VERT-Prufprotokoll festschreibt, wurde ein erster Schritt in dieser Richtung unternommen, wie der gemeinschaftliche Beitrag von TTM, AFHB, Matter Engineering, AirConsult, EMPA und Tecmot zeigt.
- Published
- 2009
40. Regio- and stereoselective isomerization of hexabromocyclododecanes (HBCDs): Kinetics and mechanism of γ- to α-HBCD isomerization
- Author
-
W. Bernd Schweizer, Heinz Vonmont, Peter Schmid, Andreas C. Gerecke, Markus Zennegg, Norbert V. Heeb, Peter Mattrel, and Regula Haag
- Subjects
Reaction mechanism ,Environmental Engineering ,Stereochemistry ,Chemistry ,Health, Toxicology and Mutagenesis ,Temperature ,Public Health, Environmental and Occupational Health ,Stereoisomerism ,General Medicine ,General Chemistry ,Pollution ,Medicinal chemistry ,Hydrocarbons, Brominated ,Substrate Specificity ,Kinetics ,Reaction rate constant ,Environmental Chemistry ,Stereoselectivity ,Enantiomer ,Isomerization ,Racemization ,Vicinal - Abstract
Hexabromocyclododecanes (HBCDs) are high production volume chemicals currently produced in quantities exceeding 20000ty(-1). They are used as flame retardants for plastics and textiles. HBCDs are thermally labile compounds, rapidly decomposing at temperatures above 250 degrees C to form bromine radicals, which scavenge other radicals formed during pyrolysis. But certain HBCD stereoisomers must reach the environment without decomposition, because their levels in soils, sediments, and biota are increasing worldwide. The fate of individual HBCD stereoisomers during production, product use, disposal, and transformation in the environment remains unclear. Herein we report on the thermally induced, highly selective isomerization of (+) and (-)beta-HBCD. Regio- and stereoselective migration of only two of the six bromine atoms resulted in the racemization of both beta-HBCDs. First order rate constants (k(rac)) increased from 0.005, 0.011, 0.021, to 0.055min(-1) at 130, 140, 150, and 160 degrees C, corresponding to half life times tau(1/2) of 143, 63, 29, and 14min, respectively. From the deduced kinetic model, we conclude that any thermal treatment of enantiomerically enriched beta-HBCDs in the range of 100-160 degrees C will result in a loss of most optical activity within few hours. The simultaneous inversion of two asymmetric centers occurred with perfect stereocontrol. Selectively, vicinal dibromides with the RR- and the SS-configurations migrated at these temperatures. An intramolecular reaction mechanism with a four-center transition state is postulated, based on the obtained stereoisomer pattern and the observed reaction kinetics. Crystal structure analysis revealed that all vicinal dibromides in beta-HBCDs prefer synclinal (gauche) conformations. However, an antiperiplanar (staggered) conformation is assumed to facilitate the concerted 1.2-shifts of both bromine atoms, resulting in an inversion of both neighboring carbon atoms. First experiments with other HBCD stereoisomers suggest that the presented isomerization mechanism is of relevance for those stereoisomers as well.
- Published
- 2008
41. Trends of NO-, NO2-, and NH3-emissions from gasoline-fueled Euro-3- to Euro-4-passenger cars
- Author
-
Anna-Maria Forss, Stefan Brühlmann, Christian J. Saxer, and Norbert V. Heeb
- Subjects
Atmospheric Science ,Cold start (automotive) ,Ozone ,Waste management ,Reactive nitrogen ,Exhaust gas ,Combustion ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Environmental chemistry ,Catalytic converter ,Nitrogen dioxide ,Nitrogen oxide ,General Environmental Science - Abstract
Vehicular emissions of reactive nitrogen compounds (RNCs) such as nitric oxide (NO), nitrogen dioxide (NO 2 ), and ammonia (NH 3 ) have a substantial impact on urban air quality. NO and NO 2 support the photochemical formation of ozone, and NH 3 is involved in the atmospheric formation of secondary aerosols. Vehicular NO is mainly formed during combustion, whereas NO 2 and NH 3 are both secondary pollutants of the catalytic converter systems. Herein we report on tail-pipe RNC emissions of gasoline-fueled Euro-3- and Euro-4-passenger cars at transient driving from 0 to 150 km h −1 . Two sets of 10 in-use vehicles with comparable engine size and mileage were studied with time-resolved chemical ionization-mass spectrometry (CI-MS). Each vehicle was tested in 7 different driving cycles including the legislative European (EDC) and the US FTP-75 driving cycles. Mean emission factors (EFs) for different traffic situations are reported and effects of cold start, velocity, acceleration, and deceleration are discussed. Furthermore, critical operating conditions supporting the de novo formation of NH 3 have been identified. In the EDC, mean NO- and NH 3 -EFs of 57±26 and 16±12 mg km −1 were obtained for Euro-3-vehicles; those of the Euro-4-technology were lower by about 25% and 33% at the levels of 43±46 and 10±7 mg km −1 , respectively. NO 2 emissions of the investigated three-way catalyst (TWC) vehicles accounted for 3 was found to be the dominant RNC for most vehicle conditions. Molar NH 3 proportions varied from about 0.4–0.8, as soon as catalyst light-off occurred. NO was found in large excess only during the cold-start period. Catalyst light-off is indicated by a fast transition from NO- to NH 3 -rich exhaust. Velocity and acceleration had pronounced effects on the RNC emission characteristics. Mean velocity-dependent EFs for NO and NH 3 varied by about one order of magnitude from 10 to 74 and 15 to 161 mg km −1 for Euro-3-vehicles and from 12 to 44 and 7 to 144 mg km −1 for the Euro-4 fleet. We conclude that the investigated Euro-3- and Euro-4-vehicles are mainly operated under slightly reducing conditions, where the NH 3 emissions dominate over those of the NO. Under these conditions, both vehicle fleets on an average fulfilled the valid Euro-3 and Euro-4 limits for nitrogen oxides (NO x ) of 150 and 80 mg km −1 , respectively (as NO 2 equivalents).
- Published
- 2008
42. Solid-state conformations and absolute configurations of (+) and (−) α-, β-, and γ-hexabromocyclododecanes (HBCDs)
- Author
-
Peter Schmid, W. Bernd Schweizer, Martin Kohler, Regula Haag, Peter Mattrel, Markus Zennegg, Andreas C. Gerecke, Max Wolfensberger, and Norbert V. Heeb
- Subjects
Models, Molecular ,Environmental Engineering ,Stereochemistry ,Health, Toxicology and Mutagenesis ,Molecular Conformation ,Stereoisomerism ,Crystal structure ,Crystallography, X-Ray ,Mass Spectrometry ,Stereocenter ,chemistry.chemical_compound ,Alkane stereochemistry ,Environmental Chemistry ,Molecule ,Flame Retardants ,Molecular Structure ,Public Health, Environmental and Occupational Health ,Absolute configuration ,General Medicine ,General Chemistry ,Pollution ,Hydrocarbons, Brominated ,Cycloalkane ,chemistry ,Enantiomer ,Chromatography, Liquid - Abstract
Hexabromocyclododecanes (HBCDs) are high production volume chemicals used as flame retardants for plastics and textiles. They are currently produced in quantities exceeding 20,000 t/y. Despite this fact, the correct stereochemistry of most HBCDs is still not known. Six stereocenters are formed during bromination of cyclododecatrienes, resulting in mixtures of different stereoisomers. Considering all elements of symmetry, 16 different stereoisomers including six pairs of enantiomers as well as 4 meso forms are possible theoretically. Recently, we isolated 8 of the 16 possible stereoisomers from a technical HBCD mixture and assigned their relative configurations. Herein, we report on the isolation of 6 enantiomerically pure alpha-, beta-, and gamma-HBCDs, obtained from preparative chiral-phase liquid chromatography, and we present their absolute configurations, which were determined from X-ray diffraction analysis. The absolute configuration of (-) alpha-HBCD was found to be (1R,2R,5S,6R,9R,10S), while the one of (+) beta-HBCD is assigned to (1S,2S,5S,6R,9S,10R), whereas the one of (-) gamma-HBCD corresponds to (1S,2S,5S,6R,9R,10S). The given structural information allows the unambiguous identification of the six most important HBCD stereoisomers, which typically account for more than 95% of technical HBCDs. In addition, we compared the solid-state conformations of racemic and enantiomerically pure alpha-, beta-, and gamma-HBCDs. In all cases, vicinal dibromides adopted a synclinal (sc) conformation with torsion angles of 69+/-6 degrees. A unique structural motive was common to all examined HBCD solid-state conformations. This conserved structure was described as an extended triple turn consisting of an arrangement of three pairs of synclinal and two antiperiplanar torsion angles.
- Published
- 2007
43. Three-way-catalyst induced benzene formation: A precursor study
- Author
-
Christoph N. Zwicky, Norbert V. Heeb, Philippe Novak, Max Wolfensberger, Peter Lienemann, Matthias Trottmann, Urs Gfeller, Bastian Bommer, Hugo Huber, and Stefan Bruehlmann
- Subjects
Hydrodealkylation ,Process Chemistry and Technology ,Aromatization ,Photochemistry ,Toluene ,Catalysis ,Steam reforming ,chemistry.chemical_compound ,chemistry ,Organic chemistry ,Alkylbenzenes ,Gasoline ,Benzene ,General Environmental Science - Abstract
The implementation of the three-way-catalyst technology was the major step for pollutant abatement of gasoline vehicles. There are, however, situations, where the engine has to be operated at sub-stoichiometric combustion. At such fuel-rich conditions, an intense formation of benzene was observed over a Pd/Rh-based three-way-catalyst (TWC), when operating the catalyst in a critical temperature window of 600–730 °C. At least four different reaction pathways can lead to benzene formation on the catalyst, viz. (i) dealkylation of alkylbenzenes under steam reforming conditions, (ii) hydrodealkylation, (iii) aromatization of cyclohexanes, and (iv) cyclotrimerization of ethyne. Based on the engine-out exhaust composition only routes (i) and (ii) seem to be reasonable. The pre-catalyst application of 12 different alkylbenzenes indeed revealed that benzene formation is possible from all these precursors. At most up to 60% of the spiked precursors were converted to benzene. For meta- and para-substituted alkylbenzenes, a multi-step mechanism is proposed because partial dealkylation products such as toluene were formed as well. But a different, one-step mechanism is assumed for ortho-substituted alkylbenzenes, since no intermediates could be detected. No C–C-bond cleavage was observed within alkyl side chains. It is concluded that dealkylation reactions of alkylbenzenes are the major pathways leading to benzene formation in the TWC. Because fuel-rich combustion conditions have to be applied for the regeneration of deNOX traps or certain particulate traps as well, this chemistry might also be of relevance for these exhaust gas treatment systems.
- Published
- 2007
44. Biofuel-Promoted Polychlorinated Dibenzodioxin/furan Formation in an Iron-Catalyzed Diesel Particle Filter
- Author
-
Peter Honegger, Andreas Mayer, Jan Czerwinski, Maria Rey, Kerstin Zeyer, Yan Zimmerli, Peter Schmid, Regula Haag, Norbert V. Heeb, Joachim Mohn, Markus Zennegg, Cornelia Seiler, Adrian Wichser, and Samuel Bürki
- Subjects
Polychlorinated Dibenzodioxins ,Iron ,Polychlorinated dibenzodioxins ,Iron oxide ,Environment ,medicine.disease_cause ,Combustion ,Catalysis ,chemistry.chemical_compound ,Diesel fuel ,medicine ,Environmental Chemistry ,Organic chemistry ,Furans ,Vehicle Emissions ,Air Pollutants ,Diesel particulate filter ,General Chemistry ,Soot ,chemistry ,Biofuel ,Environmental chemistry ,Biofuels ,Chlorine ,Oxidation-Reduction ,Filtration ,Gasoline - Abstract
Iron-catalyzed diesel particle filters (DPFs) are widely used for particle abatement. Active catalyst particles, so-called fuel-borne catalysts (FBCs), are formed in situ, in the engine, when combusting precursors, which were premixed with the fuel. The obtained iron oxide particles catalyze soot oxidation in filters. Iron-catalyzed DPFs are considered as safe with respect to their potential to form polychlorinated dibenzodioxins/furans (PCDD/Fs). We reported that a bimetallic potassium/iron FBC supported an intense PCDD/F formation in a DPF. Here, we discuss the impact of fatty acid methyl ester (FAME) biofuel on PCDD/F emissions. The iron-catalyzed DPF indeed supported a PCDD/F formation with biofuel but remained inactive with petroleum-derived diesel fuel. PCDD/F emissions (I-TEQ) increased 23-fold when comparing biofuel and diesel data. Emissions of 2,3,7,8-TCDD, the most toxic congener [toxicity equivalence factor (TEF) = 1.0], increased 90-fold, and those of 2,3,7,8-TCDF (TEF = 0.1) increased 170-fold. Congener patterns also changed, indicating a preferential formation of tetra- and penta-chlorodibenzofurans. Thus, an inactive iron-catalyzed DPF becomes active, supporting a PCDD/F formation, when operated with biofuel containing impurities of potassium. Alkali metals are inherent constituents of biofuels. According to the current European Union (EU) legislation, levels of 5 μg/g are accepted. We conclude that risks for a secondary PCDD/F formation in iron-catalyzed DPFs increase when combusting potassium-containing biofuels.
- Published
- 2015
45. Benzene, toluene and C2-benzene emissions of 4-stroke motorbikes: Benefits and risks of the current TWC technology
- Author
-
Christian J. Saxer, Anna-Maria Forss, Norbert V. Heeb, and Claudio Rudy
- Subjects
chemistry.chemical_classification ,Atmospheric Science ,Cold start (automotive) ,Analytical chemistry ,Environmental engineering ,Exhaust gas ,Toluene ,law.invention ,chemistry.chemical_compound ,Hydrocarbon ,chemistry ,law ,Catalytic converter ,Alkylbenzenes ,Aromatic hydrocarbon ,Benzene ,General Environmental Science - Abstract
Chemical ionization mass spectrometry has been applied to determine benzene, toluene and C 2 -benzene emission rates of 4-stroke motorbikes. Extra emissions and duration of the cold start were deduced from the legislative urban driving cycle. The Common Artemis driving cycle was investigated to study the emission characteristics at transient driving from 0 to 135 km h −1 . In addition, the benefits and risks of the currently available 3-way catalyst technology (TWC) are explored. Benzene, toluene and C 2 -benzene cold start emissions of 230–290, 920–980 and 950–1270 mg start −1 were obtained for the TWC motorbikes, exceeding those without catalyst by more than a factor of 3. At hot engine/catalyst, benzene, toluene and C 2 -benzene emission factors in the range of 10–140, 10–160 and 10–170 mg km −1 were found for the TWC motorbikes. Without catalyst, the corresponding emission factors were higher, varying from 40 to 260, 100 to 500 and 110 to 480 mg km −1 , respectively. A comparison with the latest passenger car technology, with reported aromatic hydrocarbon (HC) emission factors of 0.2–3.0 mg km −1 , revealed that the investigated 4-stroke motorbikes, indeed, are an important source of air pollution. Furthermore, cold start duration, driving distance under cold start influence and velocity dependence of aromatic HC emissions were deduced from time-resolved data. In addition, variations of aromatic HC mixing ratios were studied. Narrow and unimodal distributions of, e.g. benzene/C 2 -benzene mixing ratios with median values of 0.46–0.73 were found for all motorbikes but one. This motorcycle, equipped with a TWC, showed a broad and bimodal distribution with a median mixing ratio of 1.47. Catalyst-induced formation of benzene from alkylbenzenes is the assumed process, leading to increased benzene/alkylbenzene mixing ratios.
- Published
- 2006
46. Three-way catalyst-induced formation of ammonia—velocity- and acceleration-dependent emission factors
- Author
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Anna-Maria Forss, Stefan Brühlmann, Norbert V. Heeb, Paul Hug, Christian J. Saxer, and Roland Luscher
- Subjects
Atmospheric Science ,Environmental engineering ,Analytical chemistry ,Exhaust gas ,Selective catalytic reduction ,Combustion ,law.invention ,Catalysis ,Ammonia ,chemistry.chemical_compound ,chemistry ,law ,Catalytic converter ,Mixing ratio ,Nitrogen oxide ,General Environmental Science - Abstract
Ammonia (NH 3 ) is classified as a toxic air pollutant but its release from vehicles is not regulated. Herein we report on the efficiency of the catalytic reduction of nitrogen monoxide (NO) and the selectivity towards NH 3 . Chemical ionization mass spectrometry (CIMS) has been applied to monitor NH 3 and NO emissions at a time resolution of 2 s. At real world driving, intense, catalyst-induced NH 3 formation was detected for a gasoline-fueled passenger car equipped with a Pd/Rh-based three-way-catalyst (TWC). Post-catalyst NH 3 emissions strongly depend on velocity and acceleration and varied by two orders of magnitude from 1 to 170 mg km −1 . For most vehicle conditions, tail-pipe NH 3 emissions exceeded those of NO. Excellent NO conversion above 95% was noticed as soon as catalyst light-off occurred. Post-catalyst NO emissions were lowest when NH 3 formation was most intense and vice versa. This complementary behavior indicates that a TWC can be operated in a way that either NH 3 or NO emissions dominate. The NH 3 /NO mixing ratio was mainly influenced by the air-to-fuel ratio. At fuel-rich combustion ( λ 3 /NO mixing ratios clearly above one were observed, whereas ratios at or below one were found at lean conditions ( λ > 1 ). Catalyst temperature effected the selectivity of the DeNOx process. Highest NH 3 selectivity up to 0.45 was found when operating the catalyst below 280 °C. Above this temperature, the selectivity was reduced to 0.02–0.05. The obtained results highlight those parameters, influencing the NH 3 output of a TWC vehicle at real world driving.
- Published
- 2006
47. Correlation of hydrogen, ammonia and nitrogen monoxide (nitric oxide) emissions of gasoline-fueled Euro-3 passenger cars at transient driving
- Author
-
Stefan Brühlmann, Norbert V. Heeb, Anna-Maria Forss, and Christian J. Saxer
- Subjects
Pollutant ,Pollution ,Atmospheric Science ,Cold start (automotive) ,Hydrogen ,media_common.quotation_subject ,Exhaust gas ,chemistry.chemical_element ,chemistry ,Atmospheric chemistry ,Environmental chemistry ,Gasoline ,NOx ,General Environmental Science ,media_common - Abstract
Ammonia (NH3) emissions from gasoline-fueled vehicles have become an important source of pollution affecting urban air chemistry. NH3 influences the acidity of atmospheric depositions and it is involved in secondary aerosol formation. NH3 has to be considered as a secondary pollutant of the three-way-catalyst (TWC), since it is formed de novo during the DeNOx process. The extent of traffic-related hydrogen (H2) emissions and its impact on atmospheric redox chemistry is not well understood but is of increasing importance when we develop towards a hydrogen-based society. Herein we report on tail-pipe H2, NH3, and NO emissions of gasoline-fueled Euro-3 passenger cars at transient driving from 0 to 150 km h−1. The effects of velocity, acceleration, deceleration, and cold start were deduced from time-resolved EI- and CI-MS data. On a molar basis, H2 emissions were always higher than those of NH3 and NO by about an order of magnitude. H2 and NH3 emissions are correlated to some degree, as soon as catalyst light-off occurred. NH3 emissions exceeded those of NO for most vehicle conditions. Mean NH3/NO mixing ratios around two were observed with the exception of the cold start, where NO was present in large excess. Catalyst light-off is indicated by a fast transition from a NO- to a NH3-rich exhaust gas. All emissions clearly depend on speed and acceleration. Mean velocity-dependent emission factors varied by about one order of magnitude from 17 to 720, 8 to 170, and 7 to 80 mg km−1 for H2, NH3, and NO, respectively, with emission minima for all three pollutants when driving 70–90 km h−1. We conclude that the investigated Euro-3 vehicles are mainly operated under slightly reducing conditions, where NH3 and H2 emissions dominate over those of NO. Under these conditions, all vehicles fulfill the valid emission limit for NOx.
- Published
- 2006
48. Regulated and nonregulated diesel and gasoline cold start emissions at different temperatures
- Author
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Christian J. Saxer, Anna-Maria Forss, Martin Weilenmann, Patrik Soltic, and Norbert V. Heeb
- Subjects
Pollutant ,chemistry.chemical_classification ,Atmospheric Science ,Cold start (automotive) ,Engineering ,Chassis dynamometer ,Waste management ,business.industry ,Environmental engineering ,Air pollution ,medicine.disease_cause ,Methane ,Diesel fuel ,chemistry.chemical_compound ,chemistry ,medicine ,Volatile organic compound ,Gasoline ,business ,General Environmental Science - Abstract
The emissions of modern cars are usually reduced in warm engine conditions by catalysts. Consequently emissions are significantly higher during the cold start, i.e. the warm-up phase of the car. The duration of this period and the emissions produced during it depend on the ambient temperature as well as on the initial temperature of the car's systems. The cold start emissions of Euro-3 gasoline cars, Euro-2 diesel cars and old pre-Euro-1 gasoline cars were investigated at cold ambient temperatures. Since the goal was to get real-world emissions, the measurements were done with cars belonging to private owners taken straight from the road with no maintenance. The chassis dynamometer tests were carried out at +23, −7 and −20 °C. The test cycle employed is a representative urban ride from a real-world driving behaviour study. Besides the regulated pollutants, methane, benzene and toluene were also measured online by chemical ionisation mass spectrometry.
- Published
- 2005
49. Anaerobic Degradation of Decabromodiphenyl Ether
- Author
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Markus Zennegg, Norbert V. Heeb, Peter Schmid, Paul C. Hartmann, Andreas C. Gerecke, Martin Kohler, Walter Giger, and Hans-Peter E. Kohler
- Subjects
Time Factors ,Polybrominated Biphenyls ,Ether ,Decabromodiphenyl ether ,Bacteria, Anaerobic ,chemistry.chemical_compound ,Octabromodiphenyl ether ,Halogenated Diphenyl Ethers ,Animals ,Environmental Chemistry ,Organic chemistry ,Flame Retardants ,Chromatography ,Sewage ,Phenyl Ethers ,Diphenyl ether ,Extraction (chemistry) ,General Chemistry ,Biodegradation ,Bromine ,Biodegradation, Environmental ,chemistry ,Water Pollutants, Chemical ,Sludge ,Environmental Monitoring - Abstract
The environmental safety of decabromodiphenyl ether (BDE-209), a widely used flame retardant, has been the topic of controversial discussions during the past several years. Degradation of BDE-209 into lower brominated diphenyl ether congeners, exhibiting a higher bioaccumulation potential, has been a critical issue. Here, we report on the degradation of BDE-209 and the formation of octa- and nonabromodiphenyl ether congeners under anaerobic conditions. Sewage sludge collected from a mesophilic digester was used as the inoculum and incubated up to 238 days with and without a set of five primers. Following Soxhlet extraction and a liquid chromatography cleanup procedure, parent compounds and debromination products were analyzed by GC/HRMS. In experiments with primers, concentrations of BDE-209 decreased by 30% within 238 days. This corresponds to a pseudo-first-order degradation rate constant of 1 x 10(-3) d(-1). Without primers, the degradation rate constant was 50% lower. Formation of two nonabromodiphenyl ether and six octabromodiphenyl ether congeners proved that BDE-209 underwent reductive debromination in these experiments. Debromination occurred at the para and the meta positions, whereas debromination at the ortho position was not statistically significant. All three nonabromodiphenyl ether congeners (BDE-206, BDE-207, and BDE-208) were found to undergo reductive debromination as well. No significant change of the BDE-209 concentration and no formation of lower brominated congeners was observed in sterile control experiments. To our knowledge, this is the first report demonstrating microbially mediated reductive debromination of BDE-209 under anaerobic conditions.
- Published
- 2005
50. Benzene: A Secondary Pollutant Formed in the Three-Way Catalyst
- Author
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Norbert V. Heeb, Stefan Bruehlmann, Anna-Maria Forss, and Dominik Steffen
- Subjects
chemistry.chemical_classification ,Air Pollutants ,Chemical ionization ,Chemistry ,Environmental engineering ,Analytical chemistry ,Exhaust gas ,Benzene ,General Chemistry ,Hydrocarbons, Aromatic ,Toluene ,Catalysis ,Mass Spectrometry ,law.invention ,chemistry.chemical_compound ,Hydrocarbon ,Orders of magnitude (specific energy) ,law ,Catalytic converter ,Environmental Chemistry ,Environmental Monitoring ,Vehicle Emissions - Abstract
Benzene emissions from a relevant proportion of today's gasoline-driven passenger cars and light-duty vehicles can increase by up to 2 orders of magnitude when driving at high engine load (e.g., on highways). Under such conditions, post-catalyst benzene levels exceeded those found pre-catalyst. As a consequence, formation of benzene in the catalyst was postulated. To further reduce ambient air concentrations of benzene, these critical operating conditions must be carefully avoided. Here, we report in detail to what extent and at what operating conditions catalyst-induced benzene and toluene formation can occur. For that purpose, a EURO-1 passenger car (1.8 L, model year 1995) fulfilling the valid regulations, equipped with a new, two-layered, Pd-CeO2-AI2O3/Rh-ZrO2-AI2O3 three-way catalyst was operated at steady state on a chassis dynamometer at 100, 125, and 150 km/h at variable air to fuel ratios. Pre- and post-catalyst exhaust gas concentrations of benzene, toluene, C2-, and C3-benzenes were monitored at a time resolution of 0.5 Hz by means of chemical ionization mass spectrometry. A net benzene formation window, ranging from pre-catalyst exhaust gas temperatures of 600- 730 degrees C and l-values of 0.83-0.95, with a pronounced minimum at 0.87, was observed. Dealkylation reactions of aromatic hydrocarbons are assumed to be the major pathway leading to benzene. (A)
- Published
- 2004
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