Diss. (sammanfattning) Örebro : Örebro universitet, 2007. / Härtill 5 uppsatser.

Diss. (sammanfattning) Umeå : Umeå universitet, 2007. / Härtill 6 uppsatser.

Diss. (sammanfattning) Örebro : Univ., 2005. / Härtill 5 uppsatser.

Under en rutinmätning av emissioner 2019 överskred SCA Munksund AB gränsvärdetför dioxiner vid samförbränning. Som en direkt åtgärd minskades andelen avfallsklassatbränsle i bränsleblandningen. För att skaffa sig en bättre bild av hur olika avfalls-andelar påverkar dioxinbildningen, med säkrade förbrännigsbetingelser, utfördes testermed avfallsandelar som varierades. Vid sidan av det gjordes en teknisk samt ekonomiskanalys av anläggningens SNCR-system. Vid anläggningen finns en fastbränslepanna av typen CFB där internt och externt bio-bränsle samt avfallsklassat bränsle energiåtervinns. Till avfallsklassat bränsle räknas re-turträ (RT-flis) och wellrejekt (plastrejekt från returfiberavdelningen). Vid förbrännings-försöken varierades mängden RT-flis mellan 0 och 10 % medan wellrejektet varieradesmellan 0 och 4 % där kravet om förbränning över 850 °C i två sekunder skulle uppnås.Andelerna är angivna med avseende på energitillförseln. Totalt testades fyra punktermellan 0 och 14 %. För framtida bruk byggdes en modell för att räkna ut uppehållstidöver 850 °C. Denna modell skulle använda sig av befintliga givare. Denna hann dock intetestas under projektets gång. SNCR-systemets styrning undersöktes och det jämfördes med befintliga licensavtal. Förden ekonomiska analysen jämfördes kostnaden för reduceringskemikalien och kväveoxid-avgiften. Resultatet visade att alla tester klarade dagens och framtidens krav om emissioner avdioxiner. Nivåerna varierade mellan 0.004-0.014 ng/m3ntg. Halterna av dioxinerna kanhärledas till hur last och temperatur i förbränningskammaren var under testerna. Högstahalten uppkom när olja stödeldades på grund av låg temperatur medan lägst halt komvid hög temperatur samt förbränning av enbart biobränsle. SNCR-systemet styrs inte enligt befintligt licensavtall samt att systemets totalekonomialltid gått med förlust. Den ekonomiska förlusten har dock ökat de senaste åren. SNCR-systemets försämrade ekonomi kommer från en högre kväveoxidavgift som resultat avhögre halter per producerad energienhet. Lägre effektivitet hos den åldrande fastbränsle-pannan och en minskad dosering av reduceringskemikalie kan tänkas vara bakomliggandeorsaken. Slutsatsen är att fastbränslepannan klarar av en andel avfallsklassat bränsle om 14 %under liknande förhållanden. SNCR-systemet styrs inte enligt licensavtalet och det finnsen möjlighet att dosera mer av reduceringskemikalien vilket kan förbättra totalekonominför systemet.i

This study has examined how cooking affects the levels of the toxicantsaflatoxin, arsenic, lead, dioxins, cadmium, mercury, perfluorinatedcompounds and polybrominated diphenyl ethers in rice, potatoes and fish.Not every toxicant was examined for all three types of food, they were onlyexamined for those types of food where current levels of the toxicant in thattype of food are relevant from a risk assessment perspective. To determineif there is a danger of negative effects due to the exposure of thesetoxicants from food, articles from the Swedish National Food Agency andother scientific articles have been compiled. A minor experimentalsubstudy was also performed where rice bought in Uppsala was rinsed andboiled in different ways to see if that affected the residue levels of arsenic.The results of this study indicate that the levels of some toxic substancescan be lowered on a dry weight basis by cooking, and that this reduction isdependent on the cooking method used, the properties of the food andtoxin. The levels of cadmium and mercury were generally unchanged bycooking whereas the results for lead and perfluorinated compounds wereconflicting. Cooking can lover the levels of aflatoxin, arsenic, dioxins andpolybrominated diphenyl ethers on a dry weight basis. The effects ofcooking on toxicant levels should be considered when performing riskassessments, but further studies are needed to achieve a better basis for decision-making.

This thesis aims to explore students’ argumentation and decision-making relating to authentic socioscientific issues (SSI). The ability to make informed decisions about socio scientific issues has been recognized to be an important element in science education to achieve the goal of scientific literacy. However, deliberation on SSIs deals with the fact-value intertwinement and has proven to be a tricky affair, both for students and teachers. In paper I, the focus is on upper secondary students’ use of different reasons in arguing about the existence of wolfs in Sweden. To investigate the students’ ability to find supporting reasons from different subject areas in their informal argumentation, the SEE-SEP model was used as an analytical framework. The results showed that the value aspect dominates students’ informal argumentation on the SSI of wolves in Sweden. In paper II a six-step SSI instructional model is presented, designed to develop students’ ability to argue about complex multi-disciplinary issues. This six-step SSI instructional model aims to create a forum that encourages students to interact with one-another and discuss their arguments dynamically. In paper III students’ argumentation and decision-making upon an authentic SSI relating to environmental toxins in fish from the Baltic Sea, was studied. The students’ argumentation and decision making processes were followed closely and data were collected during multiple stages of the SSI-instructional model. The analysis focused on students’ skills of evaluation and the relationships between the values, knowledge and experiences that they used in their argumentation. The results showed that even though all of the students had access to the same information and agreed on the factual aspects of the issue, they came to different decisions, depending on their background values, knowledge and experiences (i.e. their intellectual baggage). Implications for teaching and research are discussed. / Förmågan att fatta välgrundade beslut i sociovetenskapliga dilemman (SSI) har lyfts fram som ett viktigt inslag i naturvetenskaplig undervisning för att förbereda eleverna på ett liv som medborgare i ett samhälle där kontroversiella frågor med naturvetenskaplig koppling förekommer i allt högre grad. Att hantera SSI-frågor i undervisningen och handskas med sammanflätningen av vetenskapliga fakta, värderingar och etiska perspektiv innebär dock stora utmaningar för både elever och lärare. Fokus i denna avhandling är inriktat mot att ytterligare synliggöra de ingående komponenterna och processerna som sker i arbetet med SSI-frågor, och därmed belysa viktiga aspekter som bör iakttas vid implementering av SSI-frågor i undervisningen. Genom studie I detekteras olika argument baserade på kunskaper, värderingar respektive erfarenheter kopplat till olika ämnesområden, och i studie II förs resonemang att det s.k. intellektuella baggaget, bestående av personliga värderingar, kunskaper och erfarenheter, styr viktning och värdering av olika argument och därmed vilket beslut som slutligen tas. En given slutsats är att SSI-baserad undervisning i det naturvetenskapliga klassrummet alltid måste bygga på en tolerans för en sammanflätning av vetenskapliga fakta, värderingar och etiska perspektiv.

<p>Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzo-furans (PCDFs) belong to the most toxic compounds known to science and they are defined as Persistent Organic Pollutants (POPs) under the Stock-holm Convention. The general human exposure to PCDD/Fs is primarily through dietary intake. The importance of contaminated sites as secondary PCDD/F sources (i.e. sources that once received its contamination from a primary source) are getting increased attention. To be able to assess the risks for human exposure at PCDD/F contaminated sites, the environmen-tal distribution of PCDD/Fs and the potential mobilization between dif-ferent environmental media (e.g. food chain transfer) must be known. The primary aim of the work presented in this thesis was to investigate human exposure pathways associated with PCDD/F contaminated sites by combining field measurements and modeling. Site specific field measurements were made at a PCDD/F contaminated site in Sweden and multimedia modeling scenarios were evaluated against site specific data and national reference data.</p><p>The results show that the congener distributions in exposure media affected by contaminated soil may differ significantly from the distribu-tions found in media from reference locations. Higher chlorinated PCDD/Fs may be transferred into food chains where they contribute to a large fraction of the toxic equivalent concentration (TEQ). Ingestion of locally produced animal food may be an important exposure pathway al-ready at low or moderate PCDD/F soil concentrations. However, the con-gener composition of the source is critical for the exposure. The signifi-cance of the individual exposure routes varies depending on e.g. the spatial distribution and magnitude of the soil contamination, the pro-perties of the exposure media and the human behavior. Multimedia mo-deling can be used in risk assessments as long as model algorithms and model parameters are representative for the superhydrophobic properties of PCDD/Fs. However, selection of physical-chemical PCDD/F properties is a challenge due to large variation in reported values. For some proper-ties, data is scattered or completely lacking</p>

Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzo-furans (PCDFs) belong to the most toxic compounds known to science and they are defined as Persistent Organic Pollutants (POPs) under the Stock-holm Convention. The general human exposure to PCDD/Fs is primarily through dietary intake. The importance of contaminated sites as secondary PCDD/F sources (i.e. sources that once received its contamination from a primary source) are getting increased attention. To be able to assess the risks for human exposure at PCDD/F contaminated sites, the environmen-tal distribution of PCDD/Fs and the potential mobilization between dif-ferent environmental media (e.g. food chain transfer) must be known. The primary aim of the work presented in this thesis was to investigate human exposure pathways associated with PCDD/F contaminated sites by combining field measurements and modeling. Site specific field measurements were made at a PCDD/F contaminated site in Sweden and multimedia modeling scenarios were evaluated against site specific data and national reference data. The results show that the congener distributions in exposure media affected by contaminated soil may differ significantly from the distribu-tions found in media from reference locations. Higher chlorinated PCDD/Fs may be transferred into food chains where they contribute to a large fraction of the toxic equivalent concentration (TEQ). Ingestion of locally produced animal food may be an important exposure pathway al-ready at low or moderate PCDD/F soil concentrations. However, the con-gener composition of the source is critical for the exposure. The signifi-cance of the individual exposure routes varies depending on e.g. the spatial distribution and magnitude of the soil contamination, the pro-perties of the exposure media and the human behavior. Multimedia mo-deling can be used in risk assessments as long as model algorithms and model parameters are representative for the superhydrophobic properties of PCDD/Fs. However, selection of physical-chemical PCDD/F properties is a challenge due to large variation in reported values. For some proper-ties, data is scattered or completely lacking

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.