<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>

Large and ever-increasing numbers of chemicals, including large quantities of a broad spectrum of organic compounds are used in modern society. More than 30 000 of the more than 100 000 chemical substances registered in the EU are estimated to be daily used, of which many will be discharged into the waste-streams handled by municipal sewage treatment plants (STPs). The main objective of the work underlying this thesis was to improve understanding of the relationships between the characteristics of sewage contaminants and their sewage treatment efficiency. Further objectives were to examine the relationships between socio-economic uses of chemicals and sludge quality, and the effects of regulatory actions on sludge quality. The quality of the sewage sludge and the levels and distribution patterns of the sludge contaminants, both within and between the STPs, seem to remain quite constant over time. The overall findings indicate that the levels of contaminants in sewage sludge seem to be largely independent of the location, size and treatment techniques applied at the STPs, and generally, of the types of human activity connected to them. The total and relative concentrations of the sludge contaminants were found to be fairly constant on a dry weight basis, with some exceptions, indicating that the pollutants originate from broad usage and diffuse dispersion rather than (industrial) point sources. The proportion of cyclic methylsiloxanes recovered in sludge seems to strongly depend on their vapour pressure, which decreases with the number of siloxane units. The higher water solubility and biodegradability of organophosphorus flame retardants and plasticizers than polybrominated diphenyl ethers (PBDEs) were also reflected in lower percentages (relative to their national use) found in sludge. Significant time-trends in levels of a-third of the sludge contaminants included in the annual national measurement program were detected over a period of seven years. The levels of compounds displaying significant time-trends generally decreased following declines in the quantities used nationally. However, a quarter of these compounds showed increasing trends, of which the linear methylsiloxanes followed the same trend as used quantities. The decaBDE was also found to be increasing in sludge, probably as a result of the phase-out of pentaBDE and octaBDE. The results indicate that the STP removal efficiency of anthropogenic substances, in Sweden, is generally good and that STPs, at least those in cold climates, do not efficiently remove certain polar contaminants. A non-targeted screening (by use of environmetrics and GCxGC-TOFMS) was performed and found to fulfil the objective to assess the STP removal efficiency, with emphasis to systematically analyse which compound classes that are not efficiently removed using the current STP technology. Many polar aromatic compounds were identified to be poorly removed. The acquired data on levels, profiles and variations in sludge contaminants (sludge quality) extend both the available information and understanding of the degree and nature of sludge contamination, which should help attempts to track changes in its contaminants and revisions, if necessary, of guideline values. This thesis also contributes to improve the knowledge base for the development of future STP technologies, and that archived sewage sludge can be used in retrospective analysis of new and emerging pollutants.

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

The efficiency of wastewater treatment systems is commonly measured by the reductions of parameters such as biological oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS) and/or reductions in levels of selected macro compounds (e.g. long-chained hydrocarbons and inorganic compounds). Less attention has generally been paid to micropollutants with high potential toxic effects, such as polycyclic aromatic compounds (PACs), including unsubstituted and alkylated polycyclic aromatic hydrocarbons (PAHs) and dibenzothiophenes, polychlorinated biphenyls (PCBs), human pharmaceuticals and by-products formed during the treatment process. These organic micropollutants occur in wastewaters at trace and ultra-trace levels, therefore their detection requires advanced, costly analyses and large sample volumes. Furthermore, concentrations of micropollutants can fluctuate widely both diurnally and between days. Thus, in order to understand the fate of micropollutants in wastewaters there is a need to develop sampling techniques that allow representative samples to be readily collected. In the work underlying this thesis two types of diffusive passive samplers, semipermeable membrane devices (SPMDs) and polar organic chemical integrative samplers (POCISs), were used to monitor non-polar and polar organic micropollutants in wastewaters subjected to various treatment processes. The pollutants sequestered in these samplers represent micropollutants in the dissolved phase that are available for aquatic organisms. Further, since they collect pollutants in an integrative manner, i.e. they sample continuously during the selected exposure time (usually approx. one to ca. three weeks), the results provide time-weighted average (TWA) concentrations. In addition, the effects of various environmental factors on the uptake of analyzed micropollutants in POCISs and SPMDs were investigated using laboratory calibration and in situ calibration with performance reference compounds (PRCs). The results confirm that SPMDs are good sampling tools for investigating the efficacy of wastewater treatment processes for removing non-polar PACs and PCBs, and the effects of varying the process settings. In addition, analyses of process streams in municipal sewage treatment plants demonstrated that conventional sewage treatment processes are not optimized for removing dissolved four-ringed PAHs, some of the five-ringed PAHs, and tri- to hexa-chlorinated biphenyls. The removal of bioavailable PACs was enhanced by adding sorbents with high sorption capacities to the sludge used in the activated sludge treatment step, and a biologically activated carbon system was designed that robustly removed bioavailable PACs, with removal efficiencies of 96.9-99.7 percent across the tested ranges of five varied process parameters. In situ SPMD calibration data acquired show that uptake of PACs, described by SPMD sampling rates (Rs), were four to eight times higher than published laboratory calibrated Rs values, mainly due to strong (bio)fouling and turbulence effects. In addition, the laboratory calibration study demonstrated that temperature affects the POCIS uptake of pharmaceuticals. The uptake of four pharmaceuticals was higher, by 10-56 percent, at 18 °C compared to 5 °C. For two of the pharmaceuticals our data indicate that the uptake was lower by 18-25 percent at 18 °C. Our results also indicate that uptake of the studied pharmaceuticals was in the linear phase throughout the 35 day exposure period at both temperatures. Finally, calibration studies enabled aqueous concentrations of micropollutants to be more accurately estimated from amounts collected in the passive samplers.

Mixtures of chlorinated organic pollutants can be found in the soils at chlorophenol-contaminated sawmill, including (inter alia) polychlorinated phenols (CPs), phenoxyphenols (PCPPs), diphenyl ethers (PCDEs), dibenzofurans (PCDFs) and dioxins (PCDDs). These hydrophobic compounds have low water solubility and hence low mobility as truly dissolved compounds. However, they may migrate through the soil at significant rates via co-transport with dissolved organic matter (DOM) and colloids of fine, waterborne particulate matter. In the work underlying this thesis the distribution of chlorinated hydrophobic pollutants between these two mobile fractions in soil samples from five sawmill sites was studied Soils at five sites at which CPs were formerly used were characterized, and found to have complex profiles of chlorinated hydrophobic pollutants. CPs, PCPPs, PCDEs and PCDD/Fs were present at up to ppm-levels. Furthermore, the relative proportions of the pollutants differed from their relative proportions in the preservatives used at the sites, indicating that they have been transported from, and/or degraded in, the soil at different rates. These organic pollutants have low water solubility and strong affinity for soil organic matter (SOM). The importance of SOM for the fate of CPs, PCPPs, PCDEs, PCDFs and PCDDs in soil was investigated by examining the distribution of compounds between the mobile DOM and the immobile particulate organic matter (POM). The partitioning of CPs between DOM and POM was found to be approximately equal. However, the relative strength of association with POM of groups of chlorinated organic pollutants was positively correlated with their hydrophobicity, and thus increased in the order CP &lt; PCPP &lt; PCDE &lt; PCDF &lt; PCDD. Despite the weak association of PCDD/Fs with DOM our investigations found that considerable concentrations of these pollutants were bound to mobile fractions (DOM and colloids, &gt;0.2 µm) in both a groundwater analysis and a leaching test. CPs and PCPP were present at up to ppm- and ppb-levels, respectively, and PCDEs and PCDD/Fs at up to ppt-levels. The importance of transport in association with the mobile fraction (DOM and colloids) increased with increasing hydrophobicity e.g. PCDDs were almost entirely associated with fine particulate matter, while CPs were largely found in the water phase and only minor proportions were associated with colloids.

Large numbers of samples often need to be prepared and analysed in surveys of organic pollutants in the environment, but while the methods commonly used in such surveys can provide abundant detail they are generally costly, time-consuming and require large amounts of resources, so there is a need for simpler techniques. The work underlying this thesis assessed the potential utility of more convenient sample preparation and bioanalytical techniques for rapidly screening various environmental matrices that could be useful complements to higher resolution methods. Initially, the utility of a simplified extraction technique followed by an enzyme-linked immunosorbent assay (ELISA) for detecting polycyclic aromatic hydrocarbons (PAHs) in authentic (i.e. unspiked) contaminated soils was explored. The results showed that there are relationships between the structure and cross-reactivity among compounds that often co-occur with target PAHs. However, their potential contribution to deviations between estimates of total PAH contents of soils obtained using ELISA and gas chromatography-mass spectrometry (GC-MS) based reference methods were limited. Instead, the cross-reactivity of target PAHs and the failure to extract all of the PAHs prior to the ELISA determinations were the main reasons for these deviations. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were detected in food and feed matrices, as well as in authentic contaminated soils using different bioanalytical techniques – ELISA and two cell-based bioassays: CAFLUX and CALUX (chemically activated fluorescent/luciferase gene expression) assays. In addition, enhanced sample preparation techniques based on accelerated solvent extraction (ASE) were developed. ASE with integrated carbon fractionation (ASE-C) in combination with CAFLUX produced estimates of PCDD and PCDF contents in fish oil and fish meal that agreed well with results obtained using reference methods. Furthermore, results from ELISA and GC-high resolution MS analyses of extracts of PCDD- and PCDF-contaminated soil samples obtained using an adjusted ASE-C technique were strongly correlated. Finally, the thesis reports the first experiments in which the results of CAFLUX, CALUX, and ELISA determinations of PCDDs and PCDFs in extracts of authentic contaminated soil samples were evaluated and compared to those obtained using a reference method. All of the bioanalytical techniques were found to be sufficiently sensitive, selective, and accurate for use in screening in compliance with soil quality assessment criteria. Overall, the improved sample preparation and bioanalytical techniques examined proved to be useful potential complements to conventional methods, enhancing the analytical framework for PAHs, PCDDs, and PCDFs. However, further validation has to be undertaken before they are applied on a large-scale.

Polar organic compounds (POCs) are chemicals with polar functional groups in their structure. The functional groups make the compounds hydrophilic and less prone to partition with biota. However, the knowledge of their fate is limited due to difficulties associated with their measurements. Although, the persistence of POCs in the environment is generally low, they are considered to be semi-persistent compounds due to their continuous introduction to the environment via wastewater. Studies have shown that complex mixtures of POCs of different classes may have synergistic toxic effects on biota at environmental concentration levels. Therefore, it is important to develop analytical methods in order to establish the occurrence and fate of POCs in aquatic environments. In Study I, a positive correlation between the sorption of a novel poly(ethylene-co-vinyl acetate-co-carbon monoxide) (PEVAC) material and the theoretical logarithmic dissociation partition coefficient (Log D) for seven POCs was observed. The PEVAC material showed an enhanced sorption of the POCs compared to the silicone material. Study II, demonstrated that the PEVAC sampler assess the freely dissolved concentration of POCs in aquatic environments. The results showed that the PEVAC polymer is an attractive alternative to silicone for mimicing the biological uptake of POCs in aquatic environments. Additionally, Study II showed that total extraction is appropriate for determination of the freely dissolved concentration of uncharged POCs with Log KOW &lt; 2.67 in natural water. In study III, a novel bag-solid phase extraction (bag-SPE) technique was compared to a conventional SPE-technique. Despite that the extraction efficiencies for POCs in wastewater were lower using the bag-SPE method, the two methods showed similar detection limits due to the lower ion-suppression experienced with the bag-SPE. In study IV the bag-SPE method was further developed with the aim of lowering the detection limits for POCs. Detection limits (LOD) below 13 ng/L showed that the bag-SPE method was suitable for determination of POCs in surface sea water. / This research was financially supported by European Union (European Commission, FP6 Contract No. 003956) “Novel Methods for Integrated Risk Assessment of Cumulative Stressors in the Environment” (NoMiracle) and by the Swedish research council Formas.

Brominated flame retardants (BFRs) are chemicals used in e.g. electronic equipment, textiles and plastics for the prevention of fire. Over recent decades, concern has been raised regarding some heavily used BFRs, since the levels in the environment have been increasing. In the present thesis, persistent, bioaccumulative, and toxic (PBT) properties were studied for a structurally varied set of BFRs selected to represent more than 60 organic BFRs. The studied BFRs include: 2,4,4'-tribromodiphenyl ether (BDE 28), 2,2',3,4,4',5',6-heptabromodiphenyl ether (BDE  183), decabromodiphenyl ether (BDE 209), hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA), tetrabromobisphenol A 2-hydroxyethyl ether (TBBPA OHEE), 2,4,6-tribromophenol (246BrPh), 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), and hexabromobenzene (HxBrBz). It is likely that soil will act as a sink for BFRs. Therefore, studies of BFRs were performed on persistence in soil, and on bioaccumulation from soil in the earthworm Eisenia fetida. Large variation in the biodegradability in soil among the tested BFRs was observed. The studied brominated diphenyl ethers (BDE 28 and BDE 209) were very persistent under both aerobic and anaerobic conditions, while 246BrPh and TBECH degraded quickly in both aerobic and anaerobic soil. The bioaccumulation in earthworm from soil was high for HxBrBz, TBECH and for tested brominated diphenyl ethers with 4-6 bromine atoms (BDE 47, BDE 99, and BDE 153). Bioaccumulation was also studied in zebrafish after dietary exposure to a mixture of BFRs. It was shown that several metabolites were formed and retained in zebrafish, which highlights the importance of also searching for and identifying persistent degradation products. Maternal transfer was shown for all BFRs present in the female zebrafish. This shows that zebrafish young (fry) are exposed to these BFRs at approximately the same concentrations as female zebrafish during the early-life stages, when fish are usually most sensitive to organic contaminants. Toxicity of individual BFRs and a BFR mixture was studied in Nitocra spinipes using a silica gel-based system. Highest toxicities were observed for BDE 28, TBBPA, and TBBPA OHEE. In the mixture toxicity study, simultaneous exposure to low concentrations (individually causing no significant effect) of six BFRs significantly affected the survival of Nitocra spinipes. The results from the PBT studies presented in the thesis and literature data were compared with the criteria for PBT classification, as set in the European REACH legislation. Further, some BFRs with physico-chemical properties similar to those of identified PBTs were suggested to be prioritized for future PBT testing.

Due to their relative chemical stability and ubiquity in the environment, chlorinated organic contaminants such as polychlorinated biphenyls (PCBs) pose significant health risks and enduring remediation challenges. Engineered nanoparticles (NPs) provide a novel platform for sensing/remediation of these toxicants, in addition to the growing use of NPs in many industrial and biomedical applications, but there remains concern for their potential long-term health effects. Research highlighted herein also represents a transdisciplinary approach to address human health challenges associated with exposure to PCBs and NPs. The objectives of this dissertation research are two-fold, 1) to develop effective methods for capture/sensing and remediation of environmental toxicants, and 2) to better understand associated risks and to elucidate relevant protective mechanisms, such as lifestyle-related modulators of environmental disease. Prevalent engineered nanoparticles, including aluminum oxide and titanium dioxide, have been studied to better understand effective nanoparticle dispersion methods for in vitro nanotoxicology studies. This work has served both to effectively stabilize these nanoparticles under physiological conditions and to better understand the associated mechanisms of toxicity, which links these metal nanoparticles to endothelial oxidative stress and inflammation through phosphorylation of key cellular signaling molecules and increased DNA binding of pro-inflammatory NFκB. Surface functionalization, though, is being found to limit potential toxicity and has been utilized in subsequent research. A novel polyphenol-functionalized, NP-based system has been developed which combines the biomimetic binding capabilities of nutrient polyphenols with the separation and heating capabilities of superparamagnetic iron oxide NPs for the capture/sensing of organic contaminants in polluted water sources. Magnetic nanocomposite microparticles (MNMs) incorporating the fluorescent polyphenols quercetin and curcumin exhibit high affinity for model organic pollutants followed by rapid magnetic separation, addressing the need for sustainable pollutant remediation. Further work has been performed to both better understand health concerns associated with environmental toxicants such as PCBs and to determine effective methods for modulating their toxicity. This research has shown that PCB remediation through dechlorination is a viable technique for decreasing endothelial inflammation, although complete dechlorination to biphenyl is necessary to effectively eliminate superoxide production, NFκB activation, and induction of inflammatory markers. Additionally, the nutrient polyphenol EGCG, found in green tea, has been shown to serve as a biomedical modulator of in vivo PCB toxicity by up-regulating a battery of antioxidant enzymes transcriptionally controlled by AhR and Nrf2 proteins.

Climate change is one of the largest problems facing this generation. Anthropogenically caused increases of greenhouse gas emissions is a significant culprit to this problem. Although the obvious problems such as cars, industry, and urbanism garnish a significant amount of the criticism, natural sources such as wetlands are also beginning to contribute to this issue. This is becoming increasingly significant as wetlands shift from being sinks of greenhouse gases to becoming sources as various anthropogenic impacts, including global warming itself, begin to affect the health of the wetlands. The aim of this project is to look at four common types of wetlands, being tropical mangroves, temperate coastal marshes, inland meadows, and subarctic peatlands, all located in different climactic areas of the world, and by doing a meta-analysis of available data of greenhouse gas production for each wetland type, observe how differences in their greenhouse gas production may contribute or be affected by climate change and global warming. Results of the meta-analysis revealed that the most significant production of the potent greenhouse gas nitrous oxide occurs in coastal wetlands such as tropical mangroves and coastal marshes, while the greenhouse gas methane is seen to be produced most in subarctic peatlands. These contributions of wetlands to global greenhouse gas production are not as significant as other anthropogenic contributions. However, subarctic wetlands contribute to more than half of the global methane emissions, and the most important aspect of wetland greenhouse gas production is that they are producing more greenhouse gases than they would normally be sequestering, contributing more than the basic greenhouse gas production data can display. Global climate changes such as temperature increase and sea level rise could also make these levels of greenhouse gas production become worse, although measures to decrease the effects of this such as regulations on anthropogenic nitrogen input, macrophyte presence, and prevention of peat burning.