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  • 8651.
    Öberg, Jonas
    University of Kalmar, School of Communication and Design.
    Comparative study of operating system security using SELinux and Systrace2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis makes a comparative study of the security systemsSystrace (used primarily with OpenBSD) and SELinux (usedexclusively with Linux), trying to answer the question as to whichtype of security is offered by each respective system, and wheneach should be used. The key difference between SELinux andSystrace seems to be their mode of operation, where SELinux,built around the LSM framework in the Linux kernel, works withtype enforcement on files, sockets and other objects, whereasSystrace works on a strict system call basis. The two systems areseen to serve two different purposes which sometimes overlap,but in just as many cases provide solutions for entirely differentquality priorities.

  • 8652. Öberg, Karin
    et al.
    Warman, Kristofer
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Distribution and levels of brominated flame retardants in sewage sludge2002In: Chemosphere, ISSN 0045-6535, Vol. 48, no 8, p. 805-809Article in journal (Refereed)
  • 8653.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    A general structure-property relationship to predict the enthalpy of vaporisation at ambient temperatures.2007In: SAR and QSAR in environmental research (Print), ISSN 1062-936X, E-ISSN 1029-046X, Vol. 18, no 1-2, p. 127-139Article in journal (Refereed)
    Abstract [en]

    The vapour pressure is the most important property of an anthropogenic organic compound in determining its partitioning between the atmosphere and the other environmental media. The enthalpy of vaporisation quantifies the temperature dependence of the vapour pressure and its value around 298 K is needed for environmental modelling. The enthalpy of vaporisation can be determined by different experimental methods, but estimation methods are needed to extend the current database and several approaches are available from the literature. However, these methods have limitations, such as a need for other experimental results as input data, a limited applicability domain, a lack of domain definition, and a lack of predictive validation. Here we have attempted to develop a quantitative structure-property relationship (QSPR) that has general applicability and is thoroughly validated. Enthalpies of vaporisation at 298 K were collected from the literature for 1835 pure compounds. The three-dimensional (3D) structures were optimised and each compound was described by a set of computationally derived descriptors. The compounds were randomly assigned into a calibration set and a prediction set. Partial least squares regression (PLSR) was used to estimate a low-dimensional QSPR model with 12 latent variables. The predictive performance of this model, within the domain of application, was estimated at n=560, q2Ext=0.968 and s=0.028 (log transformed values). The QSPR model was subsequently applied to a database of 100,000+ structures, after a similar 3D optimisation and descriptor generation. Reliable predictions can be reported for compounds within the previously defined applicability domain.

  • 8654.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    A QSAR for baseline toxicity: validation, domain of application, and prediction.2004In: Chemical Research in Toxicology, ISSN 0893-228X, E-ISSN 1520-5010, Vol. 17, no 12, p. 1630-1637Article in journal (Refereed)
    Abstract [en]

    The interest in modeling and application of structure-activity relationships has steadily increased in recent decades. It is generally acknowledged that these empirical relationships are valid only within the same domain for which they were developed. However, model validation is sometimes neglected, and the application domain is not always well-defined. The purpose of this paper is to outline how validation and domain definition can facilitate the modeling and prediction of baseline toxicity for a large database. A large number of theoretical descriptors (867) were generated from two-dimensional molecular structures for compounds present in the U.S. EPA's Fathead Minnow Database (611) and the Syracuse Research Corporation's PhysProp Database (25,000+). A quantitative structure-activity relationship model was developed for baseline toxicity (narcosis) toward the fathead minnow (Pimephales promelas) using a projection-based regression technique, PLSR (partial least squares regression). The PLSR model was subsequently validated with an external test set. The main factors of variation were related to size/shape and polar interactions. The prediction error was comparable to, or slightly better than, the ECOSAR procedures. A set of 16,805 compounds, drawn from the PhysProp Database, was projected onto the PLSR model. More than 90% (15,597) of the compounds fall within the valid model domain, defined by the residual standard deviation and the leverage. The predicted baseline toxicity indicates an acute hazard for two-thirds of these compounds, classes I-III in the OECD Globally Harmonized Classification System (LC50 < or = 100 mg L(-1)). Finally, the mode of action assigned in the U.S. EPA Fathead Minnow Database was investigated. Reclassification to narcosis as the mode of action is suggested for 92 compounds, mostly from the groups "unsure" and "mixed". The present classification into specific modes of action seems to be further strengthened by the findings in this investigation.

  • 8655. Öberg, Tomas
    A QSAR for the hydroxyl radical reaction rate constant: Validation, domain of application, and prediction2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 12, p. 2189-2200Article in journal (Refereed)
    Abstract [en]

    A large number of anthropogenic organic chemicals are emitted into the troposphere. Reactions with the hydroxyl radical are a dominant removal pathway for most organic compounds, but experimentally determined gas-phase reaction rate constants are only available for about 750 compounds. The lack of experimental data increases the importance of applying structure-activity relationships (QSAR) to evaluate and predict reactivities. It is generally acknowledged that these empirical relationships are valid only within the same domain for which they were developed. However, model validation is sometimes neglected and the application domain is not always well defined. The purpose of this paper is to outline how validation and domain definition can facilitate the modeling and prediction of the hydroxyl radical reaction rates for a large database. A substantial number of theoretical descriptors (867) were generated from 2D molecular structures for compounds present in the Syracuse Research Corporationメs PhysProp Database. A QSAR model was developed for the hydroxyl radical reaction rate constant using a projection-based regression technique, PLSR (partial least squares regression). The PLSR model was subsequently validated with an external test set. The main factors of variation could be attributed to two reaction pathways, hydrogen atom abstraction and addition to double bonds or aromatic systems. A set of 17 293 compounds, drawn from the PhysProp Database, was projected onto the PLSR model and 74% were inside the applicability domain. The predicted hydroxyl reaction rates for 25% of these compounds were slow or negligible, with atmospheric half-lives in the range from days to years. Finally, the list of persistent organic compounds was matched against the OECD list of High Production Volume Chemicals (HPVC). Together with the experimental data, nearly three hundred compounds were identified as both persistent and in high volume production.

  • 8656.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bilaga till rapport Miljögifter i fisk 2001/2002 - Resultat av analyser av flamskyddsmedel i fisk från Vänern och Vättern2005Report (Other academic)
  • 8657.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bildning av dioxin: litteraturstudie och utvärdering av mätdata1992Report (Other academic)
    Abstract [sv]

    Litteraturuppgifter avseende metallers och avgaskylningens inverkan på dioxinbildning i termiska processer har sammanställts och utvärderats. Likaså har en tidigare utvärdering av svenska stålverksmätningar uppdaterats. (80 referenser). Lågtemperaturbildning bör ses som en logisk fortsättning av de förhållanden som skapas i ugnen, i form av oxidationsnivå och klorlast. Klorgas bildas från HCl genom den metallkatalyserade Deacon-reaktionen och tillgängliga aromatstrukturer (pyrolys-paket från ugnen) direktkloreras. De enkla kloraromater som bildas sammanfogas i likaså metallkatalyserade reaktioner. De mätningar som har genomförts på svenska stålverk kan i huvudsak inordnas i samma förklaringsmodell, men lågtemperaturbildningens kvantitativa betydelse är fortfarande oklar. Mätningarna som har tillkommit visar också på möjligheten att öka kunskapsunderlaget genom att använda enkla kloraromater som indikatorparametrar för dioxiner. För de stålverk som har undersökts torde det samlade dioxin-utsläppet ligga i intervallet några få till 10 gram per år. Dagens stickprovsförfarande kan däremot inte läggas till grund för några meningsfulla beräkningar av årsutsläpp för enskilda stålverk, då den normala processvariationen är alltför stor.

  • 8658.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Boiling points of halogenated aliphatic compounds: a quantitative structure-property relationship for prediction and validation.2004In: Journal of chemical information and computer sciences, ISSN 0095-2338, E-ISSN 1520-5142, Vol. 44, no 1, p. 187-192Article in journal (Refereed)
    Abstract [en]

    Halogenated aliphatic compounds have many technical uses, but substances within this group are also ubiquitous environmental pollutants that can affect the ozone layer and contribute to global warming. The establishment of quantitative structure-property relationships is of interest not only to fill in gaps in the available database but also to validate experimental data already acquired. The three-dimensional structures of 240 compounds were modeled with molecular mechanics prior to the generation of empirical descriptors. Two bilinear projection methods, principal component analysis (PCA) and partial-least-squares regression (PLSR), were used to identify outliers. PLSR was subsequently used to build a multivariate calibration model by extracting the latent variables that describe most of the covariation between the molecular structure and the boiling point. Boiling points were also estimated with an extension of the group contribution method of Stein and Brown.

  • 8659.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Book Review: Risk Management in Post-Trust Societies2006In: Risk Analysis, Vol. 26, p. 859-861Article in journal (Other academic)
  • 8660.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Book Review:: Risks and Decisions for Conservation and Environmental Management2005In: Risk Analysis, ISSN 0272-4332, E-ISSN 1539-6924, Vol. 25, no 6, p. 1685-1687Article, book review (Other academic)
  • 8661.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Brominated aromatics from waste handling and recycling processes: The Flame Retardants Project1994Report (Other academic)
    Abstract [en]

    Emissions of brominated aromatics from waste handling and recycling processes are discussed based on a number of investigations and measurements in waste incineration plants, steel plants and at waste landfills. Bromine in municipal waste at present levels does not seem to cause unacceptable environmental risks when treated in incineration plants with good combustion conditions and efficient flue gas cleaning. A significant increase of the bromine flow with the waste may result in an increased production of brominated aromatics. Flame retardants are important as bromine carriers, but not as specific precursor compounds. Scrap-metal re-melting processes are presently studied in an extensive test programme initiated by the industry, and a report is due in the summer of 1993. Accidental fires in waste landfills are discussed with the background of the high emissions of chlorinated aromatics. Significant emisssions of brominated aromatics can also be expected, irrespective of the bromine carrier. Precursors may play a role in this situation. (21 references).

  • 8662.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Chemicals in Statistics - Method Development2009Report (Other academic)
    Abstract [en]

    Statistics on import, manufacture, and export of chemicals can be an important information source to follow up the results of environmental policy and management decisions. In this pilot study we evaluate the use of the official trade and manufacture statistics for the purpose of screening for bioaccumulating and persistent compounds of a particular environmental relevance. An impact index to measure these properties is applied to chemical groupings in the trade statistics. Furthermore, data from the trade statistics for selected chemicals is compared to corresponding data from the Swedish Products Register, at the Swedish Chemical Agency.

    The results show that the level of detail in the trade statistics does not permit estimation on the impact index using a compound specific index for environmental impact. In the trade statistics, a substantial number of chemicals with different properties are often grouped with the same identifier. However, this study shows that it is possible to use the same index to identify the groups containing the most problematic chemicals.

    The 100 chemicals identified to rank highest with regard to the potential environmental impact index belong to several groups, but 94 of these were halogenated. The two dominating groups in the trade statistics were halogenated aromatics and hydrochlorofluorocarbons (HCFC), with 25 and 20 members, respectively.

    A more detailed study of the trade statistics for these high-impact groups revealed substantial deviations between data from Statistics Sweden and Swedish Chemical Agency. Anomalies and an outlier were also observed and some misclassifications discovered. The self-reported statistics thus seems to need further validation to improve their usability for chemical policy purposes. Suggestions are made for further comparisons of databases, but tracing back to primary sources may also prove necessary to ensure relevance and good quality.

     

  • 8663.
    Öberg, Tomas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Data needs for socio-economic analysis - bridging the gap between safety and impact assessments2012In: Contemporary Concepts in Toxicology, Society for Toxicology , 2012Conference paper (Other academic)
  • 8664.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Förekomst av PCB och PCN i varor och kemiska produkter i Sverige: Kloruppdraget, underlagsrapport 51994Report (Other academic)
    Abstract [sv]

    Tomas Öberg Konsult AB har på uppdrag av Kemikalieinspektionen utrett förekomsten av polyklorerade bifenyler (PCB) och polyklorerade naftalener (PCN) i varor och produkter. Faktaunderlag har samlats in från tidskriftsartiklar, rapporter och genom personliga kontakter (ca 80 referenser). I Sverige förekommer inte längre någon registrerad nyanvändning av PCB eller PCN. Användningen av PCB-fyllda transformatorer och kraftkondensatorer kommer att vara helt avvecklad vid utgången av 1994. Båda ämnesgrupperna kan dock förekomma som föroreningar i andra produkter. Särskilt vad avser PCN är läget oklart då det inte helt kan uteslutas att användning fortfarande förekommer någonstans i världen. Endast ett fåtal analysresultat finns avrapporterade som avser PCB i svenska produkter. Dessa liksom litteraturreferenser visar att något förhöjda halter fortfarande kan förekomma i returpappersprodukter. Vad avser ackumulerade mängder av PCB så återfinns huvuddelen, mellan 150-600 ton, i byggnadsmaterial. Det största massflödet av PCB, 3-30 ton per år, kan förväntas via byggavfall. För PCN saknas i stort sett helt uppgifter om förekomst i produkter, ackumulerade mängder och massflöden. Kontrollerad förbränning är sannolikt en källa av mindre betydelse för utsläpp av både PCB och PCN. Andra termiska industriprocesser har ej värderats. Bränder kan ge upphov till utsläpp med åtminstone lokalt mätbar betydelse.

  • 8665.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Halogenated aromatics from steel production: results of a pilot-scale investigation2004In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 56, no 5, p. 441-448Article in journal (Refereed)
    Abstract [en]

    The potential environmental impact of emissions of halogenated aromatics from the steel industry is of growing concern. It has been suggested that electric arc furnaces are the only industrial source with constant or increasing emissions of dioxins to air. Here the results are reported from a pilot plant study on how scrap composition and various treatment alternatives affect the formation and release of chlorinated and brominated aromatics. The experiments were conducted with a statistical mixture design, and it is shown that scrap composition has a significant impact on the outcome. In contrast, the various treatment schemes examined--shredding, disassembly, and briquetting--did not affect the formation and release of halogenated aromatics. Parallel experiments with injection of adsorbents showed that it is possible to reduce emissions without substantial investments, and this option is recommended as a low-cost solution.

  • 8666.
    Öberg, Tomas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Importance of health and environmental impact assessments for the evaluation of restriction proposals and authorisation applications under REACH2012In: Presentation vid European Environment & Public Health Consultative Conference (3d EPH Annual Meeting) i Krakow, 25-27 oktober, 2012., 2012Conference paper (Other academic)
  • 8667.
    Öberg, Tomas
    Multisimplex, Gullberna Park.
    Importance of the first design matrix in experimental simplex optimization1998In: Chemometrics and Intelligent Laboratory Systems, ISSN 0169-7439, E-ISSN 1873-3239, Vol. 44, no 1-2, p. 147-151Article in journal (Refereed)
    Abstract [en]

    The basic and modified simplex methods are efficient optimization techniques applied in many fields of chemistry and engineering. Various first design matrices were evaluated on polynomial models with added noise. D-optimal linear design matrices performed better than regular or cornered first simplices in the normal experimental situation. These findings have been implemented in a new experimental design an optimization software, the MultiSimplex(R).

  • 8668.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Indicator parameters for PCDD/PCDF from electric arc furnaces2004In: Chemometrics and Intelligent Laboratory Systems, ISSN 0169-7439, E-ISSN 1873-3239, Vol. 73, no 1, p. 29-35Article in journal (Refereed)
    Abstract [en]

    The unintentional formation and release of persistent organic pollutants (POP) from industrial sources is of environmental concern and efforts are now made to reduce these emissions [The Stockholm Convention on persistent organic pollutants; United Nations Environment Programme: Geneva, 2001]. The emissions of chlorinated trace organics from electric arc furnaces (EAF) have been monitored on a regular basis in Sweden since the 1980s. Most analyses have encompassed not only polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF), but also chlorinated benzenes and phenols. Emissions of 2,3,7,8-substituted PCDD/PCDF from municipal solid waste incinerators (MSWI) can be modelled and predicted from analyses of chlorinated benzenes and phenols, which are suspected to be precursors in the formation process. The purpose of this investigation was to extend and update previously reported models with new samples from EAF, to describe the main sources of variation and to compare multivariate calibration with univariate regression. The measurement data consisted of 27 samples collected between 1987 and 2002 and analysed by two different laboratories. A general multivariate calibration model was able to describe 96% of the variation in the toxic equivalent quantity (TEQ) value over five orders of magnitude. Univariate regression models cannot account for changes in the congener pattern and thus gave a poorer performance. In plant-specific applications, the univariate approach did, however, perform equally well. It was therefore concluded that both multivariate and univariate regression models can be used in process optimisation studies, but that multivariate models are better suited for emission monitoring and evaluation of removal efficiencies in the off-gas cleaning systems.

  • 8669.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Introducing chemometrics to graduate students2006In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 83, p. 1178-1181Article in journal (Refereed)
    Abstract [en]

    Chemometric methods enjoy an ever-increasing popularity, and there is a need to introduce more graduate students to these research tools. This article describes an introductory course covering design of experiments, pattern recognition, and multivariate calibration. The course was composed of a series of formal lectures, seminars, and practical computer exercises followed by a project assignment tailored to each participant's own research. The teaching was focused to a few statistical methods, selected for their usefulness in solving chemical research problems. The mathematics was kept to a minimum, practical aspects and conceptual understanding were highlighted, and the exercises confronted the students with a diverse set of applications. The use of a ready-made training package—from one of the developers of chemometrics software—facilitated the course preparations and also provided the senior researchers with an opportunity for self-study. The challenge that now lay ahead at our university is to create an environment that can stimulate and support the future use of these rational methods for chemical research.

  • 8670.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Karakterisering av dioxininnehåll i avfall: en litteratursammanställning2003Report (Other academic)
    Abstract [sv]

    Föreliggande rapport redovisar resultat från en litteraturstudie avseende förekomst av dioxiner i hushållsavfall. Antalet undersökningar med primära data som avser hushållsavfall är dock ytterst begränsat. Inga undersökningar avseende förekomst av dioxiner i svenskt hushållsavfall har påträffats i litteraturen. I Europa har endast två större undersökningar redovisats efter 1995.

    Undersökningar av andra avfallsmaterial visar att den allmänna föroreningsnivån i de skandinaviska länderna är lägre än i en stor del av övriga Europa. Detta torde därför även avspeglas i det svenska hushållsavfallet. Det svenska systemet för källsortering, med olika behandlingsalternativ, gör det ändock svårt att direkt översätta resultat från andra länder och säkert uttala sig om dioxinnivån i svenskt hushållsavfall.

    Litteraturgranskningen utmynnar i slutsatsen att en undersökning av förekomsten av dioxiner i svenskt hushållsavfall skulle ge ett underlag för en fördjupad utvärdering av miljöpåverkan med olika behandlingsmetoder. Det är väsentligt att en sådan undersökning planeras så att resultatet dels kan beskriva den variation som finns inom och mellan olika avfallsfraktioner, dels kan ange mått på osäkerheten i de mätresultat som framkommer. Särskild uppmärksamhet bör ägnas åt planeringen av provtagning, analys och datautvärdering, samt kopplingen däremellan.

    • Provtagning bör utföras enligt en väldokumenterad metod.
    • De kemiska analyserna bör utföras av ett ackrediterat laboratorium.
    • Provtagningsplanering och datautvärdering bör ske med statistisk metodik. 

    Redovisade undersökningar har enbart beaktat dioxinhalten uttryckt som I-TEQ. EU's vetenskapliga livsmedelskommitté har emellertid rekommenderat att även dioxinlika PCB ska ingå i riskbedömningen. En undersökning av dioxinförekomst i svensk hushållsavfall bör därför omfatta även dioxinlika PCB (12 st kongener).

  • 8671.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Low-temperature formation and degradation of chlorinated benzenes, PCDD and PCDF in dust from steel production.2007In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 382, no 1, p. 153-158Article in journal (Refereed)
    Abstract [en]

    Dust from thermal processes may catalytically enhance the formation of chlorinated aromatic compounds under oxygen-rich conditions. The activities of two dust samples from electric arc furnaces and one from iron ore-based steelmaking (oxygen converter) were investigated in a laboratory experiment. The dust samples were heated at 300 degrees C for 2 h in an air atmosphere. The concentrations of chlorinated benzenes did not change greatly upon heating, while the concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans decreased. The addition of copper in parallel runs resulted in a substantial increase in the concentration of chlorinated benzenes, thus indicating that the experimental setup was suitable for the evaluation of low-temperature catalysis. The outcome of the experiment seems to suggest that results cannot easily be extrapolated between different thermal and metallurgical processes. Some measures to reduce emissions, such as inhibition of catalytic activity and rapid cooling, could possibly be counterproductive when applied to off-gases from the steelmaking processes investigated here.

  • 8672.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Luftutsläpp av organiska miljögifter från ljusbågsugnar: Förekomst och möjliga åtgärder för att minska miljöpåverkan2003Report (Other academic)
    Abstract [sv]

    I Sverige har mätningar av organiska miljögifter i rökgaser från ljusbågsugnar utförts sedan mitten av 1980-talet. 1992-1993 genomfördes även en litteraturstudie och en serie smältförsök vid MEFOS. Föreliggande rapport är dels en sammanfattning av mätningar och utredningar fram till början av 1990-talet, dels en uppdatering med tillkommande resultat från svenska mätningar och internationell forskning. Litteraturförteckningen upptar 167 referenser.

    Utvärderingen är till övervägande del fokuserad till de grupper av ämnen som går under beteckningen "dioxiner". Olika schema har använts under tidsperioden för att beräkna mängd toxiska ekvivalenter (TEQ), men i praktiken betyder valet av redovisningsprincip mindre än förändringar i provtagningsförfaranden och de naturliga processvariationerna. Utsläppen av dioxiner från skrotsmältning i de svenska ljusbågsugnarna har minskat med ca 70% sedan 1980-talets slut och är nu nere på nivån 3 g per år. De produktionsökningar som förutses till 2010 kommer inte att leda till ett totalt sett ökat utsläpp då produktionen vid stålverket i Degerfors upphör under 2003.

    Den utsläppsminskning som har uppnåtts beror dels på processteknisk utveckling och förbättrad stoftavskiljning, dels på strukturella förändringar i branschen. En ökad andel av produktionen sker nu vid anläggningar med låga specifika utsläpp. Halterna i rökgaserna är likväl högre än de utsläppsgränser som tillämpas i flera andra europeiska länder. I det korta tidsperspektivet är det svårt att förbättra det inkommande skrotets renhet. Ytterligare processutveckling är möjlig, men investeringskostnaderna för att införa helt nya processkoncept torde vara betydande.

    I många europeiska länder doseras nu adsorbenter, främst aktivt kol, för att förbättra avskiljningen av "dioxiner" och andra föroreningar i slangfiltren. Adsorbentdosering sker också rutinmässigt vid de svenska avfallsvärmeverken.

    De svenska stålverken har under lång tid och i samverkan byggt upp en kunskapsbas när det gäller att hantera frågeställningar kring åtgärder mot utsläpp av föroreningar och oönskad miljöpåverkan. Tidigare branschgemensamma projekt har varit framgångsrika, bl.a. genom en systematisk planering och likartat utförande av mätningar och försök. Rapporten utmynnar i en rekommendation att fortsätta med denna stegvisa strategi, som bygger vidare på tidigare erhållna resultat.

  • 8673.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Miljöriskanalys2009 (ed. 1)Book (Other academic)
    Abstract [sv]

    Miljöriskanalys omfattar, riskbedömning, riskkommunikation och riskhantering.

    I boken introduceras den teori och de metoder som är grundläggande för att hantera risk- och beslutsproblem inom miljöområdet. Olika nyckelbegrepp förklaras ingående och terminologin har anpassats till de senaste harmoniseringsförslagen. Bokens fokus är på praktisk problemlösning och dess struktur följer innehållet i riskanalysprocessen. I separata kapitel avhandlas faroidentifiering, farokarakterisering, exponeringsbedömning och riskkarakterisering. I denna del ingår även ett kapitel om sannolikhet och statistik samt ett kapitel som introducerar de senaste sannolikhetsbaserade metoderna för att beskriva osäkerheter och naturlig variation. Kapitlen därefter behandlar riskkommunikation och riskhantering av miljöproblem. Samtliga av bokens nio ämneskapitel innehåller olika tillämpningsexempel liksom instuderingsfrågor och problem att lösa själv.

    Bokens syfte är att förmedla och utveckla kunskaper om riskanalytiska metoder och dessas tillämpning inom miljöområdet, med en tyngdpunkt på kvantitativ miljöriskbedömning.

    Boken vänder sig både till universitetsstuderande, med en naturvetenskaplig eller teknisk inriktning, och till yrkesverksamma inom områdena miljö och hälsa.

  • 8674.
    Öberg, Tomas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Modeling vapor pressure.2011In: Presentation vid ECO Summer School, Leiden University, 26 september, 2011., 2011Conference paper (Other academic)
  • 8675.
    Öberg, Tomas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Non-testing methods in the safety assessment of chemicals.: Naturvetenskapligt seminarium, Kalmar, 25 november, 2011.2011Other (Other academic)
  • 8676.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Optimering är inget att vara rädd för1998In: Tidningen Automation, ISSN 0345-1011, no 8, p. 33-36Article in journal (Other (popular science, discussion, etc.))
  • 8677.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Optimisation of an industrial afterburner2003In: Journal of Chemometrics, ISSN 0886-9383, Vol. 17, no 1, p. 5-8Article in journal (Refereed)
  • 8678.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Persistent Organic Pollutants and the Environment: A Chemometric Approach to the Study of Halogenated Aromatics2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Concern is growing about the environmental and health effects of persistent organic pollutants (POPs), many of which are halogenated aromatic compunds. The research reported in this thesis focuses on factors determining their behaviour and release into the environment. The aims have been to relate molecular features with physical and chemical properties and to interpret casual relationships, with the common methodological approach of chemometrics.

    Quantitative structure-property relationships (QSPR) were investigated for polychlorinated biphenyls (PCB), polychlorinated diphenyl ethers (PCDE) and polybrominated diphenyl ethers (PBDE). QSPR models were developed from computationally derived descriptors using partial least squares regression (PLSR). The results show that it is possible to model and predict properties such as vapour pressure almost to the limit of the experimental error. The models obtained could be applied both to validate available experimental data and extend the current database of experimental determinations.

    The distribution and levels of brominated flame retardants (BFRs) in sewage sludge were investigated using exploratory data analysis (EDA), analysis of variance (ANOVA) and principal component analysis (PCA). The levels of polybrominated diphenyl ethers (PBDE) and biphenyls (PBB) agreed well with another investigation reported recently, but for tetrabromobisphenol A (TBBPA) there was a divergence, possible due to the analytical methodology. The variation among wastewater treatment plants was statistically significant, and three distinct types of technical products were shown to contribute.

    The formation and release of chlorinated aromatics was investigated in an industrial afterburner with a series of statistically design experiments. Th effect of temperature was studied with some detail and the results indicate different decomposition pathways for hydrocarbons and chlorinated aromatics. Additional factors were studied in a multifactor experiment, with a full factorial design in two blocks. Catalytic lowtemperature formation and chlorine input were both statistically highly significant factors. Polychlorinated dioxins (PCDD) and dibenzofurans (PCDF) showed a statistically significant correlation to chlorinated benzenes, and the results could thus be described and interpreted within a simple conceptual model. The efficiency of the final oxidation, the chlorine input and the presence of a catalyst (e.g. copper) control the thermal formation of the different groups of chlorinated aromatics.

    The reported investigations show that empirical 'soft' models can provide insight and understanding of complex chemical properties and reactions. Latent variable models and Taylor polynomials were able to approximate the behaviour of these systems within the investigated boundaries. The chemometric models and methods are thus likely to find use also in other areas of environmental science where theoretical understanding is still limited.

  • 8679.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Prediction of gas chromatographic separation for PBDE congeners from molecular descriptors2004In: The ESS Bulletin, ISSN 1651-5382, Vol. 2, no 1, p. 74-90Article in journal (Refereed)
    Abstract [en]

    Polybrominated diphenyl ethers (PBDE) have been identified as environmental contaminants with a widespread distribution. The separation properties of PBDEs in high-resolution gas chromatography (HRGC) are important both for environmental analysis and for determining physical properties such as the vapour pressures. This study reports a quantitative structure-property relationship (QSPR), established between relative retention times on capillary HRGC and two constitutional structure descriptors that can perform equally well as more elaborate approaches. The simplified approach is recommended for explanatory models, while a more in-depth multivariate characterisation is suggested to assure similarity in applying prediction models.

  • 8680.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Prediction of physical properties for PCB congeners from molecular descriptors2001In: Internet Journal of Chemistry, Vol. 4, no 11Article in journal (Refereed)
  • 8681.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Prediction of vapour pressures for halogenated diphenyl ether congeners from molecular descriptors2002In: Environmental Science and Pollution Research, ISSN 0944-1344, Vol. 9, no 6, p. 405-411Article in journal (Refereed)
  • 8682.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Probabilistisk riskbedömning fas 1.: Sannolikhetsbaserad uppskattning av miljö- och hälsorisker i förorenade markområden – en litteraturöversikt.2006Report (Other academic)
    Abstract [en]

    Contaminated sites and land result in adverse health effects and environmental risks. This literature review show how the present methodology for quantitative risk assessment can be supported by a probabilistic approach. The probabilistic method involves a characterisation of variability (natural variation) and uncertainty(lack of knowledge). This information can be used to support better decisions andalso provide better insight on how to refine the assessment. The probabilistic methodologyhas become widely used in the United States and is gaining popularity in several European countries.

    Probabilistic risk assessments are generally based on simulations of possible outcomes from a large number of possible settings for input variables and model parameters. The calculations can now be performed on an ordinary PC, but some basic skills are required to fully comprehend both the possibilities and the limitations of the methodology.

    Contaminated land is together with the nuclear industry the most important environmental application for probabilistic risk assessment, and a substantial number of studies have been published for sites in North America, Europe and Asia. Thesestudies include pollution by lead, arsenic, chromium, uranium, PCB, PAH, hexachlorobenzene, pentachlorophenol, dioxins and chlorinated solvents. The probabilistic risk assessments cover different types of exposure in a diverse set of operations, including metallurgical industry (melting and mining operations), manufacturing industry, gas plants, wood impregnation, infrastructure, and waste landfills.

    An increase use of probabilistic risk assessment will require quality assurance procedures and the U. S. EPA has issued a rather detailed guideline document, which also reflects the current scientific consensus. Similar guidelines are needed in Europe.

    The need to characterise variability, uncertainty and sensitivity in risk assessment models in Sweden is not different than the need in North America. In addition, the margins of safety must be clearly defined. Probabilistic methods can easily be incorporated into the present Swedish risk assessment models and the report presents an example calculation for benzo[a]pyrene.

    Probabilistic risk assessments have often been used to establish site-specific remediation goals and this is projected to an important future application in Sweden. The report suggests that there is a need to establish a framework to simplify the evaluation and interpretation, and recommends that a guidance document be compiled. Training and education is also needed. Courses are already part of the curricula at some universities, but there is also a need for further training and education of working professionals, both by distance education and shorter problem based courses.

  • 8683.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Production of halogenated aromatics from waste incineration – indicator parameters and operational control1987In: Proceedings från Swedish Flame Days, Studsvik, 8-9 september, 1987, 1987Conference paper (Other academic)
  • 8684.
    Öberg, Tomas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Read-across and QSARs in the risk assessment of food and feed2010In: Presentation vid Experts Workshop on "Dealing with Uncertainty of Non-Test Methods under REACH" i Helsingfors, 23-24 september, 2010., 2010Conference paper (Other academic)
  • 8685.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Replacement of PCBs (polychlorinated biphenyls) and HCB (hexachlorobenzene): the Swedish experience1996In: Alternatives to persistent organic pollutants: the Swedish input to the IFCS expert meeting on persistent organic pollutants in Manila, the Philippines, 17-19 June 1996, Solna: Kemikalieinspektionen , 1996Chapter in book (Other academic)
    Abstract [en]

    The total import to Sweden of PCB between 1957-1980 has been estimated to 8,000-10,000 metric tonnes. A substantial part of the import, probably more than 50% was re-exported in goods. The use of PCB in Sweden has been restricted since 1972, and in 1978 it was decided that no new permits to use PCB in new products should be issued. Remaining part in the power sector of the industry has also been removed. Transformers or capacitors containing PCB and with a higher rating than two kilovoltamperes (reactive) may not be used after the 31st of December 1994.

    PCB containing transformers were never manufactured in Sweden. The problem with PCB filled transformers and contaminated transformer oils has therefore been less severe, compared to many other industrialized countries. The main chemical alternative to PCB in transformers is mineral oil with different additives.

    PCB was used in the manufacture of capacitors in Sweden before 1978. The use for this purpose accounted for about 80% of the import of PCB. Chemical alternatives for PCB as capacitor fluid include a multitude of chemical compounds. The capacitor fluid most frequently used today in Sweden is a mixture of methyl(phenylmethyl)benzene and methylbis(phenylmethyl)benzene.

    PCB was used in different building materials as a plasticiser. Chemical alternatives include chlorinated paraffins and phthalates. Chlorinated paraffins are however replaced due to environ-mental concerns, and it has also been decided to phase out the phthalates. Substantial amounts of PCB, an estimated 190-650 metric tonnes, still remain in buildings. It is obvious that measures to deal with these problems may cost many times more than the replacement already accomplished.

    Destruction capability and capacity are keys to a successful and final solution to the PCB problem. The destruction cost is also the major cost factor in the replacement. 17,667 metric tonnes of PCB containing waste was received by SAKAB, the Swedish hazardous waste treatment plant, between 1987-1995. This gives an idea of how much PCB wastes that have to be handled.

    Minor amounts of HCB (hexachlorobenzene) has been used in some parts of the Swedish industry. HCB has not been manufactured in Sweden and previous use has been replaced. Estimates of the international production are contradictory. It therefore seems premature to neglect HCB as an organic micro-pollutant of environmental concern.

  • 8686.
    Öberg, Tomas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Socio-economic analysis in the REACH regulation: Impact assessment to support risk management2014Conference paper (Other academic)
  • 8687.
    Öberg, Tomas
    European Chemicals Agency (ECHA), Helsinki, Finland.
    Substitution of chemicals based on assessment of hazard, risk and impact2014In: Journal of Risk Research, ISSN 1366-9877, E-ISSN 1466-4461, Vol. 17, no 5, p. 565-568Article in journal (Other academic)
  • 8688.
    Öberg, Tomas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    The role of EFSA in integrated food-environment risk assessments2010In: Presentation vid ILSI Europe 2010 Annual Symposium i Bryssel, 25-26 mars, 2010., 2010Conference paper (Other academic)
  • 8689.
    Öberg, Tomas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Under strecket: Gruvinspektören som uppfann naturen2016In: Svenska Dagbladet, Kulturdelen, no 18 oktober, p. 24-24Article in journal (Other (popular science, discussion, etc.))
  • 8690.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Validering av prediktionsmodeller för NOx-mätning1996Report (Other academic)
    Abstract [sv]

    Indirekt bestämning NOx-utsläpp med hjälp av prediktionsmodeller kan godtas för bestämning av miljöavgift. Kraven på tillförlitlighet förutsätts bli likartade som för mätutrustningar. Rapporten redovisar hur prediktionsmodeller bör utformas för att motsvara dessa krav.

    Ett stort antal anläggningar i USA använder redan nu prediktionsmodeller för att bestämma utsläppet av kväveoxider. De förslag till valideringskrav som har föreslagits är likartade som för mätutrustningar. Modellen skall upprättas utifrån mätdata från jämförande mätningar där olika driftsinställningar provas. Verifieringen genomförs likartat, med ett specificerat prestandakrav för precision och riktighet.

    I Sverige är detaljerade kvalitetskrav för prediktionsmodeller ännu inte fastställda. Följande punkter måste dock beaktas:

    - Ingångsdata för modelluppbyggnad.

    - Modellverifiering - rekalibrering.

    - Prestanda och definition av kalibreringsområde.

    - Kontroll av giltighet och signalvalidering.

    En genomgång av resultat från två genomförda projekt visar att indirekt bestämning av kväveoxider är tekniskt möjlig.

    Rapporten avslutas med ett förslag till "översättning" av Naturvårdsverkets nuvarande prestandakrav för mätinstrument. Det viktigaste prestandakraven för prediktionsmodellerna vid jämförande mätningar är att den systematiska skillnaden liksom standardavvikelsen högst får uppgå till 10% av kalibreringsområdet och högst 10 ppm tg.

  • 8691.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Varför så tyst om riskerna med nano?2005In: Ny Teknik, Vol. Nr. 20, den 18 majArticle in journal (Other (popular science, discussion, etc.))
  • 8692.
    Öberg, Tomas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Virtual screening for environmental pollutants: structure-activity relationships applied to a database of industrial chemicals2006In: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 25, no 4, p. 1178-1183Article in journal (Refereed)
    Abstract [en]

    The current risk paradigm calls for individual consideration and evaluation of each separate environmental pollutant, but this does not reflect accurately the cumulative impact of anthropogenic chemicals. In the present study, previously validated structure-activity relationships were used to estimate simultaneously the baseline toxicity and atmospheric persistence of approximately 50,000 compounds. The results from this virtual screening indicate fairly stable statistical distributions among small anthropogenic compounds. The baseline toxicity was not changed much by halogen substitution, but a distinct increase seemed to occur in the environmental persistence with increased halogenation. The ratio of the atmospheric half-lives to the median lethal concentrations provides a continuous scale with which to rank and summarize the incremental environmental impacts in a mixture-exposure situation. Halogenated compounds as a group obtained a high ranking in this data set, with well-known pollutants at the very top: DDT metabolites and derivatives, polychlorinated biphenyls, diphenyl ethers and dibenzofurans, chlorinated paraffins, chlorinated benzenes and derivatives, hydrochlorofluorocarbons, and dichlorononylphenol. Environmentally friendly chemicals that obtained the lowest rank are nearly all hydroxylated and water-soluble. Virtual screening can assist with "green chemistry" in designing safe and degradable products and enable assessment of the efficiency in chemicals risk management.

  • 8693.
    Öberg, Tomas
    et al.
    Studsvik AB, Nyköping 61182, Sverige.
    Aittola, Jussi-Pekka
    Bergström, Jan
    Chlorinated aromatics from the combustion of hazardous waste1985In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 14, no 2, p. 215-221Article in journal (Refereed)
    Abstract [en]

    The production and emission of chlorinated aromatics from a hazardous waste incinerator were shown to be influenced by the operating conditions. The emissions of chlorinated benzenes, PCDD and PCDF show statistically significant correlations to the chlorine input. Different substance groups also correlate, and the results presented correspond well with a general formation mechanism of chlorophenols via chlorobenzenes as indicated by others.

  • 8694.
    Öberg, Tomas
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Allhammar, Göran
    Chlorinated aromatics from metallurgical industries: Process factors influencing production and emissions1989In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 19, no 1-6, p. 711-716Article in journal (Refereed)
    Abstract [en]

    The emission and production of chlorinated aromatics from metallurgical industries, e g scrap-metal re-melting, show substantial variations due to a number of process factors. The data evaluated indicates clearly that the production of chlorinated aromatics is combustion controlled.

  • 8695.
    Öberg, Tomas
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bergbäck, Bo
    University of Kalmar, School of Pure and Applied Natural Sciences.
    A review of probabilistic risk assessment of contaminated land2005In: Journal of Soils and Sediments, ISSN 1439-0108, E-ISSN 1614-7480, Vol. 5, no 4, p. 213-224Article in journal (Refereed)
    Abstract [en]

    Background, Aims and Scope. The management and decisions concerning restoration of contaminated land often require in-depth risk analyses. An environmental risk assessment is generally described as proceeding in four separate steps: hazard identification, dose-response assessment, exposure assessment, and risk characterization. The risk assessment should acknowledge and quantify the uncertainty in risk predictions. This can be achieved by applying probabilistic methods which, although they have been available for many years, are still not generally used. Risk assessment of contaminated land is an area where probabilistic methods have proved particularly useful. Many reports have appeared in the literature, mostly by North American researchers. The aim of this review is to summarize the experience gained so far, provide a number of useful examples, and suggest what may be done to promote probabilistic methods in Europe and the rest of the world. Methods. The available literature has been explored through searches in the major scientific and technical databases, WWW resources, textbooks and direct contacts with active researchers. A calculation example was created using standard simulation software. Results and Discussion. Uncertainty and variability are part of every risk assessment. Much work on risks from contaminated soil has focussed on exposure, and choice and structure of the exposure model is then a basic uncertainty factor. Other factors, e.g. parameter uncertainty, are easier to characterize. Variability can be separated into inter-individual, spatial and temporal components. Both uncertainty and variability in the exposure variables can be investigated using Monte Carlo simulation methods. These simulations enable not only the estimation of the probability for a given risk or exposure, but also add information on the sensitivity of the various input variables. This will assist the assessor in further refining the risk analysis. The large number of applications published encompasses soil contamination by lead, arsenic, chromium, uranium, polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), hexachlorobenzene, pentachlorophenol and chlorinated solvents. Probabilistic risk assessments have been used in widely different settings, such as the metallurgical industry (mining and smelting operations), manufacturing, gas plants, wood impregnation, infrastructure, and waste landfills. Site-specific remediation goals can be specified using probabilistic methods, and a guideline document has been issued within the US Superfund programme. The usability of probabilistic risk assessment is illustrated by a calculation example. The current Swedish generic guideline value for benzo[a]pyrene in contaminated soil, with ingestion of vegetables as the major route of exposure, is compared with a probabilistic estimate. The toxicological reference value corresponds well with the upper 95th percentile of the estimated variability in intake, but does not account for uncertainty in the partition coefficients. Conclusions and Outlook. The probabilistic approach to risk assessment has proved its value in characterizing variability and uncertainty, and thereby contributing to a more informed and transparent decision-making process. The management of contaminated land is a major environmental application for probabilistic risk assessments. A substantial number of studies have been published and the method is now well established in the scientific community. This development has progressed further in the United States than elsewhere, but similar applications are now being reported from Europe and Asia. Probabilistic risk assessment is used to derive soil guideline values in the United Kingdom, and other countries may be anticipated to follow. However, efficient use of probabilistic methods for risk assessment of contaminated land requires certain components. There is a requirement for quality assurance and transparency that can be met by guidelines specifying data requirements and which items to report on. Both federal and state governments in the United States have issued such guidelines, and we see a similar need from a European perspective. A second component, necessary for a successful implementation of probabilistic methods, is education. We have ourselves developed undergraduate curricula, but we also see a need for continuous education of risk assessors and decision makers. The third component required is case studies, showing how probabilistic risk assessment can be implemented successfully in the cleanup of contaminated land. Most published studies originate from the United States, so here too there is a need for the rest of the world to catch up. In addition to the three components mentioned, there is an obvious need to develop and improve methods and practice of risk communication.

  • 8696.
    Öberg, Tomas
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bergbäck, Bo
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Probabilistisk riskbedömning. Sannolikhetsbaserad uppskattning av miljö- och hälsorisker i förorenade markområden – en litteraturöversikt2005Report (Other academic)
  • 8697.
    Öberg, Tomas
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bergbäck, Bo
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Filipsson, Monika
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Catalytic effects by metal oxides on the formation and degradation of chlorinated aromatic compounds in fly ash.2008In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 71, no 6, p. 1135-43Article in journal (Refereed)
    Abstract [en]

    Polychlorinated benzenes, dibenzo-p-dioxins (PCDD), and dibenzofurans (PCDF) may be formed below the combustion temperature in fly ash from municipal solid waste incinerators (MSWI). Copper catalyzes this formation, possibly by the Deacon reaction. Many other elements are also Deacon catalysts or promoters, and here we report results from a statistically designed experiment with 15 metal oxides added to fly ash and heated at 300 degrees C for 2h in an air atmosphere. A resolution IV fractional factorial design with four replicates was completed in 36 runs with the oxides of magnesium, yttrium, titanium, vanadium, niobium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, and tin. All samples were analyzed for chlorinated benzenes and the results were evaluated by analysis of variance. The addition of copper significantly increased the amounts of the chlorinated benzenes, while cobalt, chromium and vanadium decreased the net formation. The oxides of zinc and iron seemed to have a slightly positive and negative effect respectively. The findings in this study seem to corroborate our previously reported results regarding the different catalytic effects of copper and chromium, and lack of a significant effect by nickel. Besides chromium, it also identifies cobalt and vanadium as potent catalysts for oxidative degradation of the chlorinated aromatic compounds found in MSWI fly ash.

  • 8698.
    Öberg, Tomas
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bergbäck, Bo
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Öberg, Erik
    Different catalytic effects by copper and chromium on the formation and degradation of chlorinated aromatic compounds in fly ash.2007In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 41, no 10, p. 3741-3746Article in journal (Refereed)
    Abstract [en]

    Fly ash from municipal solid waste incineration may catalytically enhance the formation and degradation of chlorinated aromatic compounds. The activities of three Deacon catalysts in this process were investigated in a statistically designed experiment. Chlorides of copper, chromium, and nickel were added to fly ash samples and the resulting samples heated at 300 degrees C for 2 h in an air atmosphere. The addition of copper increases the formation of all chlorinated aromatic compounds except the low chlorinated congeners of polychlorinated dibenzo-p-dioxins and dibenzofurans. The addition of chromium decreased the formation of most chlorinated aromatic compounds except the highest chlorinated species, where it was without effect. The addition of nickel did not show any significant effect. The outcome of the experiment can be interpreted as two competing processes: the chlorination of aromatic rings and the oxidation of carbon-carbon and carbon-oxygen bonds. The delicate balance between chlorination and oxidation could probably be further exploited to minimize both the emissions and the net production of chlorinated aromatic compounds from combustion.

  • 8699.
    Öberg, Tomas
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bergström, Jan
    Combustion test data from a Swedish hazardous waste incinerator1986In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 15, no 9-12, p. 2045-2048Article in journal (Refereed)
    Abstract [en]

    Here we present results from our tests with PCB-incineration at the SAKAB hazardous waste incinerator in Norrtorp, Sweden. Combustion tests were made with PCB both as a fluid (Arochlor 1242) and as a contaminant of solid waste (Arochlor 1016 in capacitors). A general conclusion was that the incineration of considerable amounts of PCB did not effect the production of PCDD and PCDF in this combustion plant.

  • 8700.
    Öberg, Tomas
    et al.
    STUDSVIK AB, S-61182 NYKOPING, SWEDEN .
    Bergström, Jan
    Dioxins from Scandinavian waste combustion plants1986In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 15, no 9-12, p. 2041-2044Article in journal (Refereed)
    Abstract [en]

    A large quantity of emission data for PCDD and PCDF have been reported to date. Less information is available concerning the controlling parameters for the production of chlorinated aromatics from waste combustion. Here we report results and conclusions from investigations carried out in the Scandinavian countries to date.

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