| 1. |
- Backe, Cecilia
(författare)
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Persistent organic pollutants in the atmosphere - spatial and temporal variations
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In these thesis I have studied the spatial and temporal variations of PCBs in the atmosphere and in precipitation in southern Sweden. Further, soil-air exchange processes of PCBs were investigated. Finally, the long-range transport of PCBs and DDT was studied in the Baltic Sea region and in a tropical vs. a temporal region. On the regional scale there were significant differences in PCB concentration in the atmosphere, in precipitation and in soil between nearby sampling-areas. Differences in PCB concentrations between areas probably originated from varying geographical and meteorological conditions that affected exchange processes between air and soil/vegetation surfaces. Temporal variations in PCB concentration in atmosphere and precipitation were also found. For PCBs in the air, a systematic pattern in the deviation from the yearly median value for the region was observed. Wind direction played an important role for PCB concentration in precipitation in coastal areas, while at the inland sites this variable seemed to have a minor influence. To examine the intensity of precipitation scavenging, the total washout ratios were calculated and the highest ratios were observed at the two sites where PCB concentration in the air was high. Further, high concentrations of PCB in precipitation correlated with a composition of highly chlorinated PCB congeners, as shown by principal component analysis. For most of the sites there was a significant negative relationship between PCB concentration and rain volume. Soil type and soil organic matter content was found to be important for the variations in PCB concentration between nearby areas. Highest concentrations were found at two sites with sandy soils, one with an extremely high organic carbon content. Soils with similar soil textures (i.e. sandy silt moraine) did not show any significant differences in PCB concentrations. PCB congener composition was shown to differ between sites, with site-specific congener patterns. No significant relationships were found between air and soil concentrations of PCBs, or between deposition and soil concentrations. From fugacity quotient calculations it was shown that the soil- and air compartments for most of the sampling-areas were close to equilibrium. However, for some areas there was an outgassing of PCBs from the soil and at one site a tendency for a transport of PCBs from the air to the soil was observed. Within the Baltic Sea region a latitudinal gradient of PCBs in the atmosphere was revealed, with higher levels in the south. Further evidence of the global distillation theory was shown in a study with higher atmospheric levels of DDT in a tropical region in comparison with DDT levels in a temperate region. In accordance with the theory, DDT levels were high in fish from the temperate region, but low in fish from the tropical region.
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| 2. |
- Barri, Thaer
(författare)
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Miniaturized, Membrane-Based and Environmentally Green Sample Preparation Systems: Applications for Biological and Environmental Aqueous Samples
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Contemporary advancements in miniaturization of analytical systems have advantageously fostered development, automation, and hyphenation of a variety of sample preparation techniques. Among several downscaled extraction designs, porous synthetic polymeric membranes (such as flat sheet (FS) or hollow fiber (HF)) have been utilized for membrane-based extraction, separating two aqueous phases (as in supported liquid membrane (SLM) extraction or one aqueous phase and another organic phase (as in microporous membrane liquid-liquid extraction (MMLLE)). The SLM and MMLLE configurations permit usage of microliter-volumes of extraction solvent, and therefore, are considered to be environmentally friendly. This dissertation addresses miniaturized membrane-based extraction techniques that were operated in automated, flowing, and on-line fashion as well as in nonautomated, nonflowing, and off-line setups. These environmentally green systems based on SLM and MMLLE were appraised for trace extraction of organic compounds (such as basic and acidic pharmaceuticals (by SLM), and PCBs, OCPs, and PBDEs (by MMLLE)) in environmental and biological aqueous samples. Exhaustive extraction and non-depletive equilibrium extraction exhibiting high level of analyte preconcentration were demonstrated. The former was performed for total analyte recovery. The later was pursued so as to quantify free analyte concentration in a sample containing an analyte and a binding phase, such as a protein or humic acids. For instance, by measuring the free drug concentration, the level of drug-protein binding (DPB) was quantitatively estimated as well as the DPB process was characterized and interpreted by obtaining the binding parameters from Scatchard and Bjerrum plots. The results revealed that, although the flowing on-line systems exhibited excellent performance (e.g. the Extracting Syringe device permitting a full automation of a µMMLLE with an on-line hyphenation to gas chromatography in a closed system and limits of detection at very low ng L-1 concentration level), the flowing systems suffered from setup complexity, low extraction efficiency, and problems with analyte carryover and adsorption. By contrast, the nonautomated nonflowing designs allowed simplified and easy-to-use procedures, high analyte extraction efficiency and enrichment, and no carryover and no adsorption problems as the HF-SLM or HF-MMLLE device was employed for only a single use. In conclusion, the HF-based, nonautomated, and nonflowing setups of SLM and MMLLE have been shown to have attractive merits when employed for exhaustive as well as non-depletive equilibrium sampling. The latter design has strong potential applications for speciation of freely dissolved organic compounds, and a promising development is expected in its application for environmental and biological samples.
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| 3. |
- Bergström, Staffan
(författare)
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Strategy for Monitoring Organic Pollutants in Waste Water with Focus on Improved Sample Preparation
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Strategy and methodology is presented for the analysis of organic pollutants, with the purpose of evaluating treatment procedures for landfill leachate. Today, many investigations of treatment procedures are focusing on the measurement of water quality parameters such as chemical and biochemical oxygen demand, (COD and BOD), and total organic carbon, (TOC) when assessing the organic compounds in waste waters. These parameters give an unclear picture of the actual organic constituents. A developed analytical protocol, the Laqua protocol, covers several classes of organic contaminants, including both polar and non-polar markers, as well as inorganic parameters. As markers for polar compounds some phenols are selected and for non-polar markers polychlorinated biphenyls (PCB) and polybrominated diphenylethers (PBDE) are used. Unidentified markers are also followed to back up trends. The monitoring of individual compounds gave valuable information in understanding the processes in the treatment procedures. A toxicity test suitable for leachate water based on the crustacean Artemia Salina was also developed and included in the evaluation protocol. Combined with a simple fractionation of the leachate water, this test gave valuable information about the origin of the toxicity, which mainly originated from ammonium. The protocol was implemented and tested on a pilot plant for different treatment procedures in Kristianstad, Sweden. The bottle neck in the complicated analysis of organic pollutants is the expensive and resource demanding sample preparation step. In this thesis focus has been on developing automated, cost effective analytical procedures with sample preparation based on membrane technology. For PCBs, phthalates and organochlorine pesticides (OCP), automated procedures have been based on membrane-GC methodology, and for phenols an automated system, based on membrane-LC methodology, has been developed. A simple very efficient method based on disposable hollow fibre has been developed for the analysis of PBDE with GC-MS for final determination. All the developed methods dramatically decrease the time and effort spent on sample preparation, and demand only a very small fraction of organic solvents compared to conventional methods. The developed methods have very good performance, and as an example PCB extracted from 1 ml sample in 10 minutes gave detection limits of 2 - 3 ng/l, and relative standard deviations (RSD) at 0.1 µg/l of 1.6 - 5.0 % for all ten PCB congeners investigated.
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| 4. |
- Karlsson, Daniel
(författare)
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Airborne Isocyanates, Aminoisocyanates and Amines
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Isocyanates are used in the production of polyurethane (PUR). Exposure to isocyanates is associated with respiratory disorders and may occur during production or processing of PUR. During thermal degradation of PUR, amines and aminoisocyanates are formed in addition to isocyanates. Some isocyanates and several aromatic amines are sensitizers and listed as carcinogens. A liquid chromatography mass spectrometry (LC-MS) method for simultaneous determination of isocyanates, aminoisocyanates and amines in gas and particle phase was developed. Air samples were collected in midget impinger flasks, containing di-n-butylamine (DBA) in toluene, and glass fibre filters in series to form specific DBA-isocyanate derivatives. Amines were derivatized with ethyl chloroformate. Derivatives were characterized using both LC-MS and LC-chemiluminescent nitrogen detection. Gas chromatography with MS and thermionic specific detection was also used. LC-MS detection resulted in a highly sensitive measurement of isocyanates equivalent to 1/2000 of the Swedish threshold limit value (for TDI in a 5 L air sample). In air samples from spray painting operations, aliphatic isocyanates that have not been reported previously were revealed. In car repair shops, during work operations such as welding in PUR-coated metal sheets, isocyanates, aminoisocyanates and amines were observed at high concentrations in both gas and particle phase. Compounds with high volatility were efficiently collected in the impinger flask, whereas compounds with low volatility were mainly found on the filter. Isocyanic acid (ICA) and methyl isocyanate (MIC) were among the most dominating compounds present. ICA and MIC could also be observed when urea-based resins were thermally degraded.
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| 5. |
- Nammari, Diauddin
(författare)
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Seasonal and Long-Term Storage of Baled Municipal Solid Waste
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Baling of MSW has been extensively used in Sweden and other countries for the storage of energy (biomass for energy) for incineration and production of either and or electricity and heat. Baling is performed in two principally different ways, leading to cylindrical- or rectangular bales. This work has focused on various parameters during the storage of MSW. The first parameters investigated were gaseous emissions CO2, O2, CH4 and volatile organic compounds (VOCs) from cylindrical and rectangular bales wrapped with plastic and unwrapped. A comparison of the two bale types was carried out with regard to VOCs. It was found that cylindrical and rectangular bales differ significantly. The emission of aromatic organic compounds was predominant in rectangular bales, while esters were predominant in cylindrical bales. Temperature was another parameter investigated. Firstly a comparison of three different interpolation methods: IDW, Thessian and ordinary kriging, was carried to enable accurate interpolation of temperature data. It was found that ordinary kriging was the most appropriate. The interpolation allowed for the 3-dimensional visualization of spatial and temporal distribution of temperature in bale storage. The interpolated temperatures were used to calculate material losses due to microbial degradation. It was estimated that between 10-15% of the structure mineralizes into carbon dioxide in 320 days. The analysis of the temperature distribution from seven different structures showed that the temperature does not increase above 70C. It was concluded that the risk of self ignition is minimal. Even though, fires do occur in storage of bale waste and in order to investigate the risk associated with a bale storage fire, a controlled fire experiment was carried out. The smoke was analyzed for various pollutant including polyaromatic hydrocarbons (PAHs) and dioxins. The concentrations measured were 15 ng/g sum of PAHs, 4.15 ng/g of naphthalene and 0.06 ng (ITEF-88)/g, 0.07 ng (ITEF-99)/ng and 0.07 ng (Eadons)/g respectively. The examples from literature and our own experiments show that waste storage areas should be more protected and prepared for fires, since a fire in a bale storage area can have a very high environmental and financial impact. Taking all in consideration, baling is an excellent method for temporary waste storage, especially for incineration. However baling is not advised as method for permanent storage as in landfills.
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| 6. |
- Reichenberg, Fredrik
(författare)
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The accessibility and chemical activity of polycyclic aromatic hydrocarbons in soil
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis proposes the use of two concepts: accessibility and chemical activity. Accessibility describes the mass quantity of PAHs that is or can become available within a given time span and under given conditions. Chemical activity quantifies the energetic state of the PAHs that determines the potential for spontaneous physicochemical processes, such as diffusion and partitioning. Chemical activity is closely related to fugacity and freely dissolved concentrations. Accessibility and chemical activity jointly govern the physicochemical part of what is known as bioavailability. Five (I-V) accompanying papers are discussed and elaborated. Paper I, is a general account of the two concepts as useful and measurable. Paper II describes a method to measure the chemical activity of PAHs in soil. Paper III is a case study; the accessibility and chemical activity of some PAHs found in a former industrial site soil were measured. Paper IV makes progress in the methodology of calibrating equilibrium sampling devices. Paper V is another case study, concerning PAHs in a highway roadside soil.
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| 7. |
- Westbom, Rikard
(författare)
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Development of Fast, Quantitative, Selective and Bioavailability-Predictive Extraction Procedures for Determination of Halogenated POPs in Environmental Matrices
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns the analysis of anthropogenic substances of the compound class known as persistent organic pollutants (POPs). Sample preparation perspectives for the analysis of POPs in the environmental matrices water, soils and sediments are presented. This thesis features reasonably cheap and uncomplicated methodology capable of fast screening of POPs. It displays how quantitative extraction of POPs can be made in a sustainable manner and how selectivity can be increased generating faster and less solvent consuming procedures compared to common practice. Also demonstrated is the potential of how selective SFE can be used in bioavailability-predictive extractions. This fast and uncomplicated methodology is capable of generating information enhancing the quality and credibility of risk assessment procedures at contaminated sites. Furthermore, the possibility of environmental analytical chemistry of POPs becoming green chemistry is been highlighted throughout the text.
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| 8. |
- Rissler, Jenny
(författare)
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Hygroscopic Properties of Aerosols from Open-Air Burning and Controlled Combustion of Biomass
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The major uncertainty in predicting the influence of human activities on global climate change is the effect of aerosols. Two physical properties of aerosols largely controlling their influence on climate are the particle number size distribution and the interaction of the particles with the surrounding water vapor. The work presented in this thesis provides new information on the interaction between atmospheric water vapor and sub-micrometer aerosol particles resulting from the combustion of biomass. The investigations extend from smoldering, slash and burn fires, to almost complete combustion. The ability of particles to interact with water vapor determines the ambient size of the particles and consequently their ability to scatter light, as well as their ability to act as condensation nuclei for cloud droplets. Their interaction with water vapor is also important regarding the influence of aerosols on human health. The dry number size distributions of the aerosols are presented and discussed, as are particle mixing status and morphology. The instruments used include a hygroscopic differential mobility analyzer (H-TDMA) for measuring the particle water uptake at subsaturation and determining mixing status, a differential mobility particle sizer (DMPS) for measuring dry number size distributions, and a cloud condensation nuclei (CCN) counter for measuring CCN concentrations. Several experiments were performed in order to study the physical properties of aerosols resulting from various kinds of biomass combustion. The results from these studies are presented together with some modeling work. Two of the experiments were performed in the Amazon basin in Brazil. In these studies the aerosol properties of the regional haze resulting from slashing and burning were studied ? both the fresh and aged biomass-burning aerosol ? and compared to the wet-season Amazonian background aerosol. The interaction between water vapor and aerosol particles containing inorganic and organic mixtures was studied in the laboratory, and water uptake was linked to chemical composition. Finally, the characteristics of particle emissions from two commercial moving-grate boilers in Sweden, operating on forest residues, were studied. The particles ranged from nearly hydrophobic to very hygroscopic, with hygroscopic diameter growth factors ranging between ~1.1 for the smoldering fires and ~ 1.8 for controlled combustion (at 90% RH). This is explained by the fact that the chemical composition of the aerosol particles is highly dependent on the combustion conditions. The components formed during complete combustion (mainly inorganic salts) and incomplete combustion (dominated by organic compounds) exhibit very different hygroscopic behavior. A model for the prediction of the CCN concentration as a function of water vapor supersaturation was developed using number size distributions and the particle diameter growth at 90% RH as input data. The model proved to reproduce the measured CCN concentrations well. The CCN spectra for the various air masses studied in the Amazon basin were parameterized and can be used for input to, and validation of, models on various temporal and spatial scales, incorporating the description of cloud formation processes. Furthermore, the Zdanovskii-Stokes-Robinson mixing rule was successfully used to predict the hygroscopic diameter growth of mixtures containing inorganic and organic compounds.
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| 9. |
- Sjökvist, Robin
(författare)
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In-situ Study of the Growth, Composition and Morphology of III-V Semiconductor Nanowires
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is widely known that nanoparticle seeded growth of III-V semiconductor nanowires often occurs via the vapor-liquid-solid mechanism. However, conventional growth of nanowires is carried out in closed systems, where mostof the details and dynamics of the growth are impossible to follow. Since all analysis is typically carried out after growth completion and transfer, only the trends in the produced growth series give hints to the processes occurringat the nanoscale.In this thesis, the growth of Au-seeded III-V semiconductor nanowires has been studied in-situ, during growth, by means of environmental transmission electron microscopy. The supply of growth species in the form of precursormolecules directly into the microscope column provides a unique opportunity to follow the nanowire growth while it is occurring, through all techniques commonly available in a transmission electron microscope. This means that nanoscale growth dynamics can be studied in real time under static or changing growth conditions, and changes in crystal structure, composition and morphology can be revealed.The present investigation highlights the relation between the liquid nanoparticle and the solid nanowire. For GaSb nanowires, I show that the nanoparticle can swell by alloying to various extents with Ga, which will influence the formed nanowire diameter. I also investigate the compositional relationship between the Au-based nanoparticles and growing ternary InGaAs nanowires, where it is established that the solidified composition is dependent on both kinetics and thermodynamics. One of the main conclusions is that a high concentration of indium in the nanoparticle is needed in order to form indium rich solid InGaAs. The in-situ investigations reveal that nanowire growth is dynamic, and the layer-by-layer growth process consists of separate steps of material collection (incubation) and solidification (step-flow). I present how the layer-by-layer growth is affected by changes in the precursor flows for GaSb nanowires, and how the formation of defects in GaAs affects growth rate and can influence the growth behavior. Finally, I discuss the multilayer growth phenomenon in InGaAs nanowires, where multiple layers nucleate and grow simultaneously at the liquid-solid interface. In many cases the results are compared to simulations and models, which can be used to provide a more detailed understanding about the factors influencing the growth. The results presented in this thesis provide fundamental insight into the growth of nanostructures and are expected to be useful in the continued pursuit of atomic scale control.
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| 10. |
- Chimuka, Luke
(författare)
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Sample Preparation of Organic Compounds in Environmental Analysis using Liquid Membrane Extraction
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis demonstrates the potential of the liquid membrane extraction technique as an alternative method for the analysis of trace ionisable organic compounds in the environment. Liquid membrane based extraction methods for the analysis of s-triazine herbicides and phenolic compounds were developed. Selectivity of the technique was demonstrated by extraction the above compounds in river water, river water spiked with high amounts of humic substances, wastewater and hydroponic nutrient solution for growing vegetables. Extracts from the various matrices analysed by reverse phase liquid chromatography with UV detection showed that they were free of interfering peaks. This therefore highlighted the liquid membrane technique as capable of selectively discriminating both polar and non-polar matrix components. Basic studies on the important parameters that influence the extraction and selectivity of the liquid membrane extraction technique were also performed. Studies showed that the first condition to achieving any extraction is analyte dissolution into the membrane. This is influenced by the polarity of both the analyte and membrane. With hydrophobic interactions as as the main mechanism of analyte dissolution into the membrane, analytes with octanol-water partition coefficients higher than 100 can be successively extracted in n-undecane or dihexyether as membrane liquids. In order to obtain high enrichment factors, complete trapping of the analytes in the acceptor is necessary. High enrichment factors can further be obtained within a relatively short extraction time by using high donor flow rate for compounds with octanol-water partition coefficients higher than 100 as the amount extracted per unit time increases for compounds with such polarity.
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