Rhamnolipids are surface-active molecules produced by Pseudomonas aeruginosa as congener mixtures. They are considered “green” alternatives to synthetic surfactants used in many applications. Optimizing yield and controlling congener distribution are necessary steps for successful commercialization. Studies have noted that vegetable oils, composed of a mixture of fatty acids, increase rhamnolipid yield. The physiological explanation for this is not yet understood. Furthermore the exact effects of various fatty acid components in the oils on rhamnolipid production have not been reported. The first part of the dissertation was to investigate rhamnolipid biosynthesis when fatty acid substrates are present. A combination of stable isotope tracing and gene expression assays were used to identify rhamnolipid lipid precursors and potential lipid metabolic pathways used in rhamnolipid synthesis. Result suggests that an octanoyl-CoA intermediate of β-oxidation is diverted from β-oxidation to de novo fatty acid synthesis via a “bypass route”, and is incorporated into either a 2-carbon or a 4 carbon β-ketoacyl- ACP, which can then be recognized by the RhlA enzyme for the biosynthesis of rhamnolipid lipid moiety. The second part of the dissertation focuses on studying how fatty acid substrates of different chain length (C₁₂ to C₂₂) and saturation (C(18:1) and C(18:2)) affect rhamnolipid yield, carbon conversion rate, and congener distribution. Results showed that stearic acid significantly increased rhamnolipid yield. A positive linear correlation between the mass percent of stearic acid used and the carbon conversion rate was observed. For all treatments, the RhaC₁₀C₁₀ was the most abundant and RhaC₁₀C(12:1) was the least abundant of the major congeners produced. However, the relative amounts of RhaC₁₀C₈ and RhaC₁₀C₁₂ congeners were dependent on several factors. In general, fatty acid substrates with relatively short chain length (C₁₂ and C₁₄), the unsaturated fatty acid C(18:2), and longer cultivation times resulted in a higher RhaC₁₀C₈/ RhaC₁₀C₁₂ ratio. The studies presented here demonstrate that the medium composition, in particular the organic substrate component, can affect rhamnolipid biosynthesis, yield, and congener distribution. Furthermore, this work presents evidence that C₁₈ fatty acids as co-substrates increase rhamnolipid yield by draining rhamnolipid intermediates directly from the β-oxidation pathway.

Polychlorinated biphenyls (PCBs) are a group of 209 persistent organic pollutants, whose documented carcinogenic, neurological and respiratory toxicities are expansive and growing. Existing inhalation estimates demonstrate ubiquitous exposure to World Health Organization (WHO) indicator PCBs and limited other PCB congeners in North America and Europe. However, inhalation exposure estimates of most lower-chlorinated congeners are lacking, and continuing release of PCBs from urban areas demands location-specific assessments of PCB exposure in ambient air and contaminated environments. Using paired indoor and outdoor airborne PCB measurements and activity questionnaires from the AESOP Study, we assess congener-specific exposure rates for adolescent children and their mothers in East Chicago, Indiana and Columbus Junction, Iowa. Our cohorts of 129 (EC) and 135 (CJ) and our detection of 202 individual congeners and coelutions allows unprecedented quantification of congener-specific inhalation exposure, which we compare to dietary exposure using Total Diet Survey PCB concentrations. ∑PCB inhalation is greater for children than for their mothers in both locations, and is greater for East Chicago mothers and children than for Columbus Junction mothers and children, respectively. Schools attended by AESOP Study children have higher indoor PCB concentrations than do homes, and contribute to more than half of children's inhalation PCB exposure. Inhalation of the potentially neurotoxic congeners PCB 11, 40/41/71, and 51 was apparent among individuals at each location. Additional, congener-specific and biological inferences are possible via comparison with sera-based PCB concentrations for these cohorts.

This work investigated the characteristics of polychlorinated dibenzo-p-dioxins anddibenzofurans (PCDD/F) in stack-flue gases from six stationary emission sources in five types ofincinerators: industrial waste incinerator (IWI), small-scale municipal solid waste incinerator(MSWI), medical waste incinerator (MWI), cement kilns (CK), and crematories (CR). These characteristics were further investigated using factor analysis and cluster analysis. Experimental results reveal that PCDDs dominate MSWI and CR, and PCDFs dominate IWIa, IWIb, CK and MWIs. The factor analysis results showed that CR and MSWI have similar fingerprints, as do IWIb and MWI3. The cluster analysis showed that if a vertical line is cut at a rescaled distance of four, then the PCDD/F congener profiles fall into four groups. The indicators of PCDD/Fs are OCDD, 1,2,3,4,6,7,8-HpCDF, 2,3,4,7,8-PeCDF, and 1,2,3,4,6,7,8-HpCDD. The emission factors of PCDD/Fs herein were from 0.0433

This study determined the polychlorinated dibenzo-p-dioxins/ dibenzo- furans (PCDD/Fs) and 22 metals contents in ash in the super heater (SH), economizer (EC), semi-dryer absorber (SDA), fabric filter (FF), fly ash pit (FAP) and bottom residue (BR) in a municipal solid waste incinerator (KTMSWI). Experimental results showed that average PCDD/FS contents in ash samples from the SH, EC, SDA, FF, FAP and BR were 0.102, 0.788, 0.210, 1.95, 2.04 and 0.0218 ng I-TEQ /g, respectively. PCDD/Fs content was very low in the SH and BR due to high temperatures (around 461¢XC in the SH and 914¢XC in combustion chamber). Conversely, total PCDD/Fs content was significantly high in ash samples from the EC (around 340¢XC), mainly because the temperature is within the favorable range of 250-400¢XC for PCDD/FS formation due to de nova reformation mechanisms. Although the SDA operated at 245¢XC, the PCDD/FS content decreased very significantly, mainly because the temperature was relatively low and because calcium carbonate was introduced into flue gases to dechlorinate and dilute chlorine-containing species. PCDD/Fs were captured by the active carbon in the FF. Furthermore, the duration that fly ash remained in the FF was longer than that for other incinerator units, and thus causing an increasing trend of PCDD/Fs level downstream (except the SDA). Total PCDD/Fs emission factors (£gg /ton-waste; £gg I-TEQ /ton-waste) in ash samples from different units were: SH (42.3; 0.846), EC (326; 6.12 ), SDA (58.1; 1.10), FF (1540; 61.3), FAP (2950; 107) and BR (537; 4.31). Most PCDD/Fs in ash were contributed by the FF (about 56%), and the generation of PCDD/Fs in ash was significant (about 35%) during the transfer process from different units to the FAP. A strong and positive correlation in a logarithmic form existed between PCDD/Fs and chlorine (Cl-) contents in ash. The results showed that principal metals in the incinerator ash were Al, Fe, Zn, Ba, Pb and Cu. On average, these six metals accounted for 96.6%, 96.8%, 97.0%, 94.2% and 96.7% of the total metals in SH, EC, SDA, FF and BR ash, respectively. The emission factors of individual metals from different units were obtained. Volatile metals, such as Cd, Sn, Sb, Hg and Pb, were mostly in fly ash, while lithophilic metals, such as Al, Fe, Ti, V, Cu, Mn, Fe, Co, Ni, Cu, Sr, Mo, Ag, Ba and Cr+6 were mainly in bottom ash. Distribution ratios for total metals in SH, EC, SDA, FF and BR ash were 4.87%, 4.26%, 2.89%, 8.17% and 79.81%, respectively. That is, about 20.2% of total metals were in fly ash and most metals (about 79.8%) were in bottom ash. The Pb content in EC ash and Hg content in FF ash were between alarm contents and maximum legal limits, while Cd and Pb contents in FF ash exceeded the maximum legal limits. The existing transportation system for transferring fly ash from different units to a fly ash pit should be modified for recycling the valuable metals. Ash with less than the alarm content for metals content, such as ash from the SH, SDA and BR, can be reused. Ash with metals exceeding the alarm contents, such as ash from the EC and FF, should be collected and transferred to a different fly ash pit for further treatment, such as metal recycling.

Bifenilas policloradas (PCBs) são componentes de óleo ascarel, usado extensamente (no Brasil até os anos 80) como isolante em transformadores de energia devido às suas propriedades físico-químicas como estabilidade térmica e alta constante dielétrica. Apesar de ter sido proibido em todo o mundo devido à alta toxicidade dos PCBs presentes em sua composição, ainda resta grande quantidade de ascarel em circulação como resíduo \"passivo\" e resultante de contaminação em trocas dos fluidos dos transformadores, além de vazamentos. A principal forma de eliminação é por incineração, que, além de ser um processo caro, pode provocar a formação de compostos mais tóxicos, as dioxinas. Por isso é importante o monitoramento da concentração dessas substâncias, a fim de evitar maiores impactos ambientais na sua disposição, bem como em estudos de biodegradação. Esta matriz é extremamente complexa, o que torna a extração e determinação desses analitos um processo trabalhoso e difícil. Neste trabalho avaliaram-se métodos de extração e determinação de PCBs presentes na solução padrão comercial PCB Congener MIX 1, SUPELCO (PCBs 10, 28, 52, 138, 153 e 180). O desenvolvimento de métodos de extração (cromatografia em coluna, extração líquido-líquido (L-L), extração em fase sólida (SPE) e micro-extração em fase sólida - SPME) dos PCBs foi seguido da determinação, por cromatografia gasosa com detector por captura de elétrons (CG/DCE), em três matrizes diferentes: óleo ascarel, amostras provenientes de reatores anaeróbios em batelada e solo. Os métodos cuja purificação e extração diminuíram o efeito dos interferentes da matriz, como SPE - Sulfoxide, cromatografia em coluna de sílica e extração L-L com n-hexano foram validados pela avaliação dos seguintes parâmetros: linearidade e faixa de aplicação; precisão instrumental; limite de detecção, limite de quantificação e recuperação absoluta. O critério de escolha entre os métodos para extração dos PCBs do óleo que forneceram maior eficiência (cartucho SPE Sulfoxide e coluna de sílica gel, após lavagem ácida; método da adição de padrão, entre 1,0 e 4,0 mg L-1) deve considerar a disponibilidade de recursos, pois a sílica gel é mais viável economicamente do que o cartucho SPE. Os valores de R2 > 0,99 para o método de extração com sílica, mesmo tendo sido considerados apenas três pontos para a curva de calibração, atestam maior linearidade do que o método com SPE Sulfoxide (R2 entre 0,97 e 0,99). A extração L-L e determinação por CG/DCE dos PCBs (padronização interna) de amostras provenientes de reatores anaeróbios em batelada (aquosas, em matriz extremamente complexa com biomassa e espuma de poliuretano para imobilização de microrganismos) foram eficientes na faixa de concentração entre 0,05 e 0,5 mg L-1. Esse método foi adequado para monitorar PCBs em estudo de degradação anaeróbia e teste de adsorção dos PCBs em espuma; forneceu linearidade com R2 entre 0,93 e 0,96 e limites de detecção de 0,048 a 0,298 mg L-1, além de recuperação absoluta entre 14,1% e 110,7%. As condições testadas por SPME não permitiram a extração dos PCBs de óleo e de solo, principalmente devido à dessorção incompleta dos PCBs da fibra de polidimetil-siloxano, de 100 μm. / Polychlorinated biphenyls (PCBs) are components of ascarel, oil widely used as insulation (until the \'80s in Brazil) due to its physicochemical properties such as thermal stability and high dielectric constant. Despite having been banned worldwide due to the high toxicity of PCBs present in its composition, there are still lots of outstanding ascarel as \"passive\" residue and resulting contamination of fluids in transformers exchanges, plus leaks. The main form of disposal is incineration, which, besides being costly, can cause the formation of more toxic compounds, that is, dioxins. It is therefore important to monitor the concentration of these substances in order to prevent further environmental impacts in their disposal, as well as in studies of biodegradation. This is an extremely complex matrix, which makes the extraction and determination of this analytes very difficult and labor intensive. In this work we have evaluated methods of extraction and determination of the PCBs present in the standard solution Congener MIX 1, SUPELCO (PCBs 10, 28, 52, 138, 153 e 180). The extraction and cleanup developed methods which reduced the effects of interfering matrix as solid phase extraction (SPE) - Sulfoxide, column chromatography on silica and liquid-liquid (L-L) extraction with n-hexane, and solid phase microextraction (SPME) after determination of the PCBs by gas chromatography with electron capture detector (GC/ECD) were validated by assessing the following parameters: linearity and range of application; instrumental precision; detection limit; limit of quantification and absolute recovery. The criterion for choosing between the methods for extraction of PCBs from the oil with a higher efficiency (SPE cartridge Sulfoxide and silica gel column, after acid washing; using the standard addition method, between 1.0 and 4.0 mg L-1) must evaluate the availability resources, since the silica gel is more economically viable than the SPE cartridge. The R2 values > 0.99 for silica extraction method, even though it was considered only three points for the calibration curve, attested higher linearity than the method with SPE Sulfoxide (R2 between 0.97 and 0.99). The L-L extraction and determination by GC/ECD of the PCBs (internal standardization) of samples from batch anaerobic reactors (aqueous, in a very complex matrix with biomass and polyurethane foam for the immobilization of microorganisms) were efficient in the concentration range between 0.05 and 0.5 mg L-1. This method was suitable to monitor PCBs in anaerobic degradation studies and its adsorption on foam; provided R2 linearity between 0.93 and 0.96 and detection limits from 0.048 to 0.298 mg L-1, as well as absolute recovery between 14.1% and 110.7%. The conditions tested for SPME technique did not allow the extraction of the PCBs from the oil and soil, mainly due to the \"incomplete dessorption\" of PCBs from the polydimethylsiloxane fiber of 100 micron.

Bifenilas policloradas (PCBs) são componentes de óleo ascarel, usado extensamente (no Brasil até os anos 80) como isolante em transformadores de energia devido às suas propriedades físico-químicas como estabilidade térmica e alta constante dielétrica. Apesar de ter sido proibido em todo o mundo devido à alta toxicidade dos PCBs presentes em sua composição, ainda resta grande quantidade de ascarel em circulação como resíduo \"passivo\" e resultante de contaminação em trocas dos fluidos dos transformadores, além de vazamentos. A principal forma de eliminação é por incineração, que, além de ser um processo caro, pode provocar a formação de compostos mais tóxicos, as dioxinas. Por isso é importante o monitoramento da concentração dessas substâncias, a fim de evitar maiores impactos ambientais na sua disposição, bem como em estudos de biodegradação. Esta matriz é extremamente complexa, o que torna a extração e determinação desses analitos um processo trabalhoso e difícil. Neste trabalho avaliaram-se métodos de extração e determinação de PCBs presentes na solução padrão comercial PCB Congener MIX 1, SUPELCO (PCBs 10, 28, 52, 138, 153 e 180). O desenvolvimento de métodos de extração (cromatografia em coluna, extração líquido-líquido (L-L), extração em fase sólida (SPE) e micro-extração em fase sólida - SPME) dos PCBs foi seguido da determinação, por cromatografia gasosa com detector por captura de elétrons (CG/DCE), em três matrizes diferentes: óleo ascarel, amostras provenientes de reatores anaeróbios em batelada e solo. Os métodos cuja purificação e extração diminuíram o efeito dos interferentes da matriz, como SPE - Sulfoxide, cromatografia em coluna de sílica e extração L-L com n-hexano foram validados pela avaliação dos seguintes parâmetros: linearidade e faixa de aplicação; precisão instrumental; limite de detecção, limite de quantificação e recuperação absoluta. O critério de escolha entre os métodos para extração dos PCBs do óleo que forneceram maior eficiência (cartucho SPE Sulfoxide e coluna de sílica gel, após lavagem ácida; método da adição de padrão, entre 1,0 e 4,0 mg L-1) deve considerar a disponibilidade de recursos, pois a sílica gel é mais viável economicamente do que o cartucho SPE. Os valores de R2 > 0,99 para o método de extração com sílica, mesmo tendo sido considerados apenas três pontos para a curva de calibração, atestam maior linearidade do que o método com SPE Sulfoxide (R2 entre 0,97 e 0,99). A extração L-L e determinação por CG/DCE dos PCBs (padronização interna) de amostras provenientes de reatores anaeróbios em batelada (aquosas, em matriz extremamente complexa com biomassa e espuma de poliuretano para imobilização de microrganismos) foram eficientes na faixa de concentração entre 0,05 e 0,5 mg L-1. Esse método foi adequado para monitorar PCBs em estudo de degradação anaeróbia e teste de adsorção dos PCBs em espuma; forneceu linearidade com R2 entre 0,93 e 0,96 e limites de detecção de 0,048 a 0,298 mg L-1, além de recuperação absoluta entre 14,1% e 110,7%. As condições testadas por SPME não permitiram a extração dos PCBs de óleo e de solo, principalmente devido à dessorção incompleta dos PCBs da fibra de polidimetil-siloxano, de 100 μm. / Polychlorinated biphenyls (PCBs) are components of ascarel, oil widely used as insulation (until the \'80s in Brazil) due to its physicochemical properties such as thermal stability and high dielectric constant. Despite having been banned worldwide due to the high toxicity of PCBs present in its composition, there are still lots of outstanding ascarel as \"passive\" residue and resulting contamination of fluids in transformers exchanges, plus leaks. The main form of disposal is incineration, which, besides being costly, can cause the formation of more toxic compounds, that is, dioxins. It is therefore important to monitor the concentration of these substances in order to prevent further environmental impacts in their disposal, as well as in studies of biodegradation. This is an extremely complex matrix, which makes the extraction and determination of this analytes very difficult and labor intensive. In this work we have evaluated methods of extraction and determination of the PCBs present in the standard solution Congener MIX 1, SUPELCO (PCBs 10, 28, 52, 138, 153 e 180). The extraction and cleanup developed methods which reduced the effects of interfering matrix as solid phase extraction (SPE) - Sulfoxide, column chromatography on silica and liquid-liquid (L-L) extraction with n-hexane, and solid phase microextraction (SPME) after determination of the PCBs by gas chromatography with electron capture detector (GC/ECD) were validated by assessing the following parameters: linearity and range of application; instrumental precision; detection limit; limit of quantification and absolute recovery. The criterion for choosing between the methods for extraction of PCBs from the oil with a higher efficiency (SPE cartridge Sulfoxide and silica gel column, after acid washing; using the standard addition method, between 1.0 and 4.0 mg L-1) must evaluate the availability resources, since the silica gel is more economically viable than the SPE cartridge. The R2 values > 0.99 for silica extraction method, even though it was considered only three points for the calibration curve, attested higher linearity than the method with SPE Sulfoxide (R2 between 0.97 and 0.99). The L-L extraction and determination by GC/ECD of the PCBs (internal standardization) of samples from batch anaerobic reactors (aqueous, in a very complex matrix with biomass and polyurethane foam for the immobilization of microorganisms) were efficient in the concentration range between 0.05 and 0.5 mg L-1. This method was suitable to monitor PCBs in anaerobic degradation studies and its adsorption on foam; provided R2 linearity between 0.93 and 0.96 and detection limits from 0.048 to 0.298 mg L-1, as well as absolute recovery between 14.1% and 110.7%. The conditions tested for SPME technique did not allow the extraction of the PCBs from the oil and soil, mainly due to the \"incomplete dessorption\" of PCBs from the polydimethylsiloxane fiber of 100 micron.

This study extends the work we have previously done by reporting on both gas-phase and particulate phase PCB concentrations in Chicago air as well as giving a first report on airborne OH-PCBs in Chicago. Gas phase PCB concentrations ranged from 43.1 pg/m³ to 2250 pg/m³, with an average concentration of 594 pg/m³ ± 445 pg/m³, and exhibited strong temporal trends. Particulate phase PCBs accounted on average for 4.3% of total PCBs in a sample. OH-PCBs were detected in both the gas and particulate phase and exhibit characteristics of either emission sources or atmospheric reactions depending on the congener.

This study focuses on a secondary contact zone between two sister species of woodrat, Neotoma fuscipes (dusky-footed woodrat) and N. macrotis (big-eared woodrat). Along the Nacimiento River, on the border of southern Monterey and northern San Luis Obispo counties, the ranges of these sister species of woodrats meet and overlap forming a secondary contact zone. The zone of secondary contact is estimated to include a 500-meter (~1,650 linear feet) portion of the Nacimiento River riparian corridor. This research examines quantifiable morphological change that is likely associated with heightened inter-specific competition within the contact zone. When in sympatry the sister species may compete for resources indirectly through exploitative competition, or directly through contest competition, or through a combination of these two processes. The prediction that heightened competition has resulted in distinctive morphological character shifts between allopatric and sympatric populations was tested my examining size and shape of adult woodrats along a 20-kilometer transect. It was confirmed that adults woodrats of the two sister taxa are morphologically distinct (N = 602) and that the phallus morphology was indeed a reliable means to identify adult male woodrats as to species (p < 0.0001, N = 331). A two model approach was used to examine convergence and divergence in size and shape of woodrats across the transect. Neotoma fuscipes exhibited a statistically significant divergerence from N. macrotis with regard to breadth of rostrum (p < 0.0001, N = 414) in a region of sympatry along the Nacimiento River. Based on the results on one statistical model, N. macrotis exhibited a statistically significant convergence with regard to body-size (p = 0.0240, N = 587) and length of hind foot (p < 0.0001, N = 563) towards those of N. fuscipes between zones of sympatry and allopatry. Alternatively, based on the results of a second statistical model that accounted for environmental variation within the system both species exhibited a statistically significant divergence with regard to body-size (p = 0.0054, N = 587) and towards that of N. fuscipes between zones of sympatry and allopatry. Also, N. macrotis exhibited a statistically significant convergence with regard to length of ear (p = 0.0022, N = 563) towards that of N. fuscipes. Based on the results of both models, detectable re-patterning of size-independent traits was observed to varying degrees. The morphological character shifts between sympatric populations and allopatric populations of woodrats suggest that ecological interactions between the species are occuring. Specifically, across the contact zone, patterns of variation in body-size and other morphological character traits are consistent with expectations of a combination of contest and exploitative competition.

In the studies underlying this thesis, various source tracing techniques were applied to environmental samples from the Baltic region. Comprehensive sampling and analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in surface sediments in Swedish coastal and offshore areas resulted in a unique data set for this region. Nearly 150 samples of surface sediments were analyzed for all tetra- to octa-chlorinated PCDD/Fs. The levels showed large spatial variability with hotspots in several coastal regions. Neither Sweden nor the EU has introduced guideline values for PCDD/Fs in sediment, but comparisons to available guidelines and quality standards from other countries indicate that large areas of primarily coastal sediments may constitute a risk to marine organisms. Multivariate pattern analysis techniques and receptor models, such as Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF), were used to trace sources. These analyses suggested that three to six source types can explain most of the observed pattern variations found in the sediment samples. Atmospheric deposition was suggested as the most important source to offshore areas, thus confirming earlier estimates. However, spatial differences indicated a larger fraction of local/regional atmospheric sources, characterized by PCDFs, in the south. This was indicated by the identification of several patterns of atmospheric origin. In coastal areas, the influence of direct emission sources was larger, and among these, chlorophenol used for wood preservation and emissions from pulp/paper production and other wood related industry appeared to be most important. The historic emissions connected to processes involving chemical reactions with chlorine (e.g. pulp bleaching) were found to be of less importance except at some coastal sites. The analysis of PCDD/Fs in Baltic herring also revealed spatial variations in the levels and pollution patterns along the coast. The geographical match against areas with elevated sediment levels indicated that transfer from sediments via water to organisms was one possible explanation. Fugacity, a concept used to predict the net transport direction between environmental matrices, was used to explore the gas exchange of hexachlorocyclohexanes (HCHs) and polychlorinated biphenyls (PCBs) between air and water. These estimates suggested that, in the Kattegat Sea, the gaseous exchange of HCHs primarily resulted in net deposition while PCBs were net volatilized under certain environmental conditions. The study also indicated that, while the air concentrations of both PCBs and γ-HCH are mostly dependent upon the origin of the air mass, the fluctuations in α-HCH were primarily influenced by seasonal changes.

Polyklorerade bifeneyler (PCB) är en problematisk organisk förorening och består av 209 olikakongener, som sorteras beroende på antal kloratomer och dess position i bifenylmolekylen. Syftet idetta arbete har varit att utveckla studier kring de förhöjda halterna av PCB i två områden med hjälpav kongenmönster för sju av kongenerna - indikatorkongenerna (∑PCB7) - som används som enindikation av totalhalten PCB. Med hjälp av kongenmönster med de olika halterna från dataunderlaggjordes statistiska analyser med PCA och MFA i Rstudio för Oxundaområdet och Stockholmsområdet,och den statistiska analysen PMF i EPA PMF 5.0 samt en undersökning av gradienter för PCB iOxundaområdet. Ett av områdena som studeras är kring Oxundasjön, en sjö norr om Upplands Väsby som sedan år2013, efter miljöövervakning, kunnat konstateras vara ett av de mest förorenade områdena när detkommer till PCB i Sverige. Oxundaområdet har sedan dess haft ett aktivt arbete av provtagningar,undersökningar och analyser kring den troliga geografiska källan men även vad det kan tänkas varaför ursprungliga produkter och är därför ett av områdena som undersöks i detta arbete. Närmareundersökningar har visat att källan med största sannolikhet är ett före detta industriområde iUpplands Väsby, så kallade Messingen, men frågetecken finns fortfarande kring när, hur och vilkaprodukter av PCB som använts i detta område. Det andra området som undersökts ärStockholmsområdet (inklusive dess skärgård, Mälaren och närliggande insjöar), där förhöjda halter avPCB framför allt påvisats i områdena närmast Stockholms stad. Resultat visar en tydlig gradient i Oxundaområdet, med höga PCB-halter i olika undersökta matriser(sediment, biota, ytvatten) i Oxundasjön, Marängsån och Rosersbergviken, som gradvis klingar avnedströms i Mälaren. PCB-halterna uppströms Oxundasjön är betydligt lägre och en tydlig ökning avhalterna syns i Väsbyån i höjd med Upplands Väsby tätort. Därtill visades att EU:s gränsvärden försaluförd fisk överstegs i Oxundasjön, Rosersbergviken och i ett fall även Borgudden. Med hjälp av PCA kunde konstateras de ytliga sedimentproverna främst hade korrelation med delägre kongenerna (PCB28 och PCB52) men även att högklorerade PCB:er (PCB138, PCB153 ochPCB180) hade högre relativ andel i vissa djupare sediment, dessa har dock med stor sannolikhetmycket låga halter. För vattenprover visade platser också nära Messingen (Väsbyån, Ladbrodammen)mer korrelation till högklorerade PCB:er. Platser längre nedströms (Marängsån, Oxundasjön och Rosersbergviken) hade mer korrelation med lägre kongenerna för vatten, likt matrisen biota, somhade en stor majoritetkorrelation med lägre kongenerna. En trolig anledning till detta är läckage frånsediment i Oxundasjöomtrådet. I Stockholmsområdet visade biota (abborre, gädda och strömming) istället en stor blandning av kongenerna, men alla platser visade korrelation högklorerade PCB:ermedan främst platser i centrala Stockholm, innerskärgård och enstaka insjöar visade flerakorrelationer till lägre kongener. För sediment visades främst korrelation med lägre kongener i Stockholmsområdet. PMF (positiv matrisfaktorisering) användes för att närmare se korrelationer med matriserna vattenoch sediment i Oxundaområdet till sju kongensammansättningar av Aroclor. För vatten visades starkkorrelation till Aroclor 1242 (och 1016) medan flertalet sediment (uppströms och i Oxundasjön)visade störst korrelation till Aroclor1260. Aroclor1242 och 1016 är de vanligaste Aroclor (64% av allproduktion av Aroclor) medan Aroclor1260 i tidigare har setts vara en av den mest persistentaAroclor i naturen, vilket kan vara förklaring till dessa resultat i Oxundaområdet. Vidare efterforskningar behöver göras för att säkerhetsställa vilka produkter som utgör källor till PCB-kontamineringen av Oxundaområdet, med fler produkter att jämföra med samt med fler kongenerän indikatorkongenerna, framför allt i vidare studier med PMF. För Stockholmsområdet behövs flerstudier där områdena delas upp, och jämföra potentiella geografiska källor till olika kongenmönster.För bättre förståelse av PCB och dess kongenmönster hade PMF för båda områdena varit lämpligmed ett större kongenuppsättning, speciellt för biota som är en av de mesta komplexa matriserna förföroreningar på grund olika faktorer av den här typen av analyser.