Essen, Universiẗat, Diss., 1999. / Dateiformat: zip, Dateien im PDF-Format.

Duisburg, Essen, Universiẗat Diss., 2003.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 153-168).

Traditional assessments of contaminated sites require the collection and analysis of field media. Specifically, sediment analysis is used to determine type of contaminant as well as total contaminant concentrations (TCC). Although TCC can be used to determine if a site is contaminated, it is unable to adequately predict exposure and bioaccumulation in organisms. Biota-sediment accumulation factors were originally introduced to calculate and predict expected exposure to organisms based on sediment TCC. As they have been shown to be unreliable with field sediments, their use is limited. Alternatively, Tenax has been examined as a tool for measuring exposure to hydrophobic organic contaminants, where the Tenax extractable concentration is related to the bioaccumulated organism concentration. Although this relationship has been demonstrated in multiple studies, few have actually related the data from multiple sites to develop a standard model of Tenax accumulation. This research had two specific goals: Develop a literature based model of Tenax accumulation of polychlorinated biphenyl congeners (PCBs) and test it's applicability to field collected sediments from the Ottawa River (OR, Toledo OH, Chapter 2) and verify the use of the model in a highly-disturbed, post-dredge system, as well as the use of Tenax as an indicator of changes in bioavailability after dredging (Chapter 3). The literature-based complete Tenax model (TM) provided a strong model for the prediction of bioaccumulation in Lumbriculus variegatus (r2=0.91). When compared to the pre-dredge data from the OR, 95% of the data were encompassed by the CTM. No bias of the model was observed across homologue groups. Subsequently, the model was used with sediments collected after remediation via dredging from the OR. In this study, the CTM encompassed 73% of the data. Although all sites along the river were considered disturbed by the dredging, resuspension, and drift of sediments, data from sites that were less disturbed were better described by the model (86% versus 64% of dredged data). Overall, the CTM is recommended for use in the prediction of exposure and accumulation of PCBs in field sediments.

Museum textiles provide priceless documentation of the activities of people throughout time. They record human interests and serve as resources for students of many disciplines. In New Zealand there are artefacts made from Phormium tenax which are extremely important in terms of providing a record of early New Zealand life and links to our past as both artistic and cultural symbols: they present an insight into the many faceted nature of early Maori culture. However there are some which are clearly in need of preservative treatment. Others may need care in the future for inevitably they are, or will be, subject to degradation during storage, when on display and during cleaning and refurbishing. Conservators, who embark occasionally on restorative treatments designed to reverse or arrest the symptoms of degradation, have begun to address the causes and future fundamental affects of their procedures. However there have been few scientific studies of the properties of the fibres and, therefore, there is little information to help the conservators in their tasks. This study has a twofold purpose. The first aim is to provide a short survey of the literature on Phormium and relate it to other lignocellulosic fibres. The emphasis in the survey is to put the conservation problem in context and to point to those technical articles which may be relevant to someone dealing with ancient materials. Secondly there is a practical study of the impact of heating the fibres in the absence and presence of oxygen and in water. These two agencies are ones which are directly relevant to the conservator.

Utsläpp av lättflyktiga organiska föreningar (VOC) är ett växande mijlöproblem. Biofiltrering är ett relativt billigt sätt att rena luft förorenad med VOC. Biofiltrering har också en fördel i att föroreningen helt bryts ned och inte endast övergår i en annan form. Rapporten beskriver arbetet kring två biofilter av kolonntyp. Mikroberna som användes kom från främst träflis och jord. Som förorening användes limonen och α-pinen. Analys skedde med gaskromatografi. Vidare undersöktes om närvaro av silikonolja i filterbädden påverkade resultatet Reningskapaciteten uppgick i filtret utan olja till ca 10 - 12 g/m3.h under de första 25 dagarna i drift och ökade därefter till ca 15 - 20 g/m3.h. Motsvarande data för det oljeberikade filtret är ca 15 - 20 g/m3.h i båda fallen / Emissions of volatile organic compounds are a growing environmental problem. Biofiltration is a relatively cost efficient method to purify air polluted with VOC:s. Biofiltraion also has the benefit of completely degrading the pollutants rather than just transferring them into another phase/form. This report describes the work on two biofilters of column type. The microbes used were extracted from wood chips and soil. As pollutants limonene and α–pinene were used. Furthermore, it was investigated how the presence of silicone oil in the filter bed affected the filtering results. The filtering capacity in the non oil enriched filter was during the first 25days 10-12 g/m3h and thereafter some 15-20 g/m3h. The efficiency of the oil enriched filter was stable at 15-20 g/m3h.

<p>Utsläpp av lättflyktiga organiska föreningar (VOC) är ett växande mijlöproblem. Biofiltrering är ett relativt billigt sätt att rena luft förorenad med VOC. Biofiltrering har också en fördel i att föroreningen helt bryts ned och inte endast övergår i en annan form. Rapporten beskriver arbetet kring två biofilter av kolonntyp. Mikroberna som användes kom från främst träflis och jord. Som förorening användes limonen och α-pinen. Analys skedde med gaskromatografi.</p><p>Vidare undersöktes om närvaro av silikonolja i filterbädden påverkade resultatet Reningskapaciteten uppgick i filtret utan olja till ca 10 - 12 g/m3.h under de första 25 dagarna i drift och ökade därefter till ca 15 - 20 g/m3.h. Motsvarande data för det oljeberikade filtret är ca 15 - 20 g/m3.h i båda fallen</p> / <p>Emissions of volatile organic compounds are a growing environmental problem. Biofiltration is a relatively cost efficient method to purify air polluted with VOC:s. Biofiltraion also has the benefit of completely degrading the pollutants rather than just transferring them into another phase/form. This report describes the work on two biofilters of column type. The microbes used were extracted from wood chips and soil. As pollutants limonene and α–pinene were used.</p><p>Furthermore, it was investigated how the presence of silicone oil in the filter bed affected the filtering results. The filtering capacity in the non oil enriched filter was during the first 25days 10-12 g/m3h and thereafter some 15-20 g/m3h. The efficiency of the oil enriched filter was stable at 15-20 g/m3h.</p>

The traditional approach for predicting the risk of hydrophobic organic contaminants in sediment is to relate organic carbon normalized sediment concentrations to body residues or toxic effects in organisms. This method is limited, however due to the plethora of variables that can influence bioavailability. Therefore, a matrix independent method of predicting bioavailability needs to be developed in order to be universally applicable. Solid phase microextraction (SPME) and Tenax are two commonly used bioavailability-based methods. While both SPME fiber and Tenax extractable concentrations can be correlated to tissue residues of aquatic species, the majority of this research (with a few exceptions) focuses on compounds that are not acutely toxic or biotransformed. Less is known about the potential applicability of these methods to predict bioaccumulation, and ultimately toxicity, for highly toxic, rapidly biotransformed compounds, such as pyrethroid insecticides. This class of compounds is of particular concern due to frequent environmental detection in sediments at concentrations lethal to benthic species. This research has four specific goals: Determining exposure conditions that may change the concentration on the SPME fibers at equilibrium (Chapter 2); Comparing the ability of SPME fibers and Tenax to predict the bioavailability of two pyrethroids (permethrin and bifenthrin) (Chapter 3); Developing bioavailability-based toxicity endpoints for bifenthrin using two aquatic species (Chapter 4); and, Validating these techniques using sediments from known contaminated field sites (Chapter 5). Overall this research was focused on comparing and contrasting the ability and applicability of SPME fibers and Tenax to adequately predict the exposure of pyrethroids under varying conditions. While comparing these two methods, they were optimized to better provide accurate predictions of bioavailability and toxicity for pyrethroids from sediments. Regardless of the fiber or animal density examined, the SPME fibers exposure did not significantly affect fiber concentrations for permethrin or DDE. Additionally, bioaccumulation of parent permethrin and bifenthrin was predicted using both SPME fibers and Tenax using 6 or 24 h extraction times. Further, a single regression model predicted bioaccumulation across compounds and species using Tenax extractable concentrations. Once demonstrated that these techniques could predict bioaccumulation, median lethal and effect levels were examined for bifenthrin and as expected the bioavailability-based endpoints were more uniform across sediments than use of whole sediment concentrations. Additionally, the relationships among the two methods were compared across multiple sediments. Despite the SPME fiber's ability to determine toxicity in laboratory sediments, the field validation study determined that lethal levels were often too low to detect on the SPME fibers using current methodologies, but Tenax extractable concentrations correlated to toxicity. Overall, while both methods could predict bioavailability, the limitations of SPME fibers including lower sensitivity, inability to function across compounds, and long equilibration time, made Tenax extraction a preferable method.

Estimating the risk of polychlorinated biphenyls (PCBs) in aquatic systems requires evaluation of exposure, usually based on exhaustive chemical extraction of sediment and potentially exposed organisms and an assessment of toxicity. Remediation can then focus on areas where the exposure leads to the highest risk. Although effective, an approach that estimates exposure, which accounts for bioavailabilty, bioaccumulation, trophic transfer potential, and transport of materials within and out of the waterway, should serve as a more comprehensive environmental assessment. The current study examined exposure of PCBs in several different trophic levels within the Campus Lake ecosystem, Carbondale, Illinois. The source of contamination and the distribution of PCBs among ecosystem components demonstrated contamination within the aquatic portion of Campus Lake and transport out of the aquatic environment to the riparian area. Several media were collected including sediment, emergent insects, spiders, and three species of fish. Sediment extractions demonstrated that PCBs were localized to one small cove and this area served as the source for transfer of PCBs to both aquatic and terrestrial organisms. Single-point 24-h Tenax extractions formed the basis for evaluating the bioavailable component of the sediment-associated PCBs with strong correlations to laboratory-based bioaccumulation assays for oligochaetes and chironomid larvae. Stable isotope data suggested that the source of carbon to the food web was relatively constant. Food web samples of emerging insects, fish, and spiders revealed that the PCBs in Campus Lake were bioavailable and the pattern of the PCB signature among food web components followed typical food web processes. The PCB congener pattern was consistent between emergent midges and spiders demonstrating the transfer of PCBs from aquatic to terrestrial species. The PCB concentrations detected in emerging insects from the contaminated area were on average 25 times greater than those detected in emerging insects from reference sites outside the area of greatest sediment contamination. High PCB concentrations found in several species of fish suggested that despite the localized sediment contamination, fish throughout the lake were exposed. These levels also exceeded the fish consumption advisory criteria. The PCB pattern comparisons suggested that the contaminated sediment was the source of exposure throughout the food web. This approach identified the scope of exposure to organisms, demonstrated bioavailability, and provided a basis for future PCB remediation and subsequent monitoring of Campus Lake. In comparison to studies focused solely on limited sampling of fish for consumption advisory purposes, this approach demonstrated the importance of more comprehensive studies to examine the range of ecosystem exposure even from very limited contamination sources.

Determining accurate exposure estimates and subsequent risk of hydrophobic organic contaminants (HOCs) in aquatic sediments requires measuring the bioavailable and/or bioaccessible concentration in sediment; as total extractable concentrations have not been found to produce accurate results. Organic carbon normalization was originally proposed as a means of accounting for the bioavailable concentration by estimating the chemical activity of the contaminant expressed as the freely dissolved chemical concentration in the interstitial water, thus correcting exhaustive extractable concentrations for the sorbing phase of sediments. Organic carbon normalization often fails, however, to accurately reflect exposure as other environmental variables (i.e. organic carbon composition, aging time of contaminants in the environment) alter desorption, such that changes in chemical activity as represented by the interstitial water concentrations are not controlled by organic carbon alone. Desorption-based samplers, such as single-point Tenax extractions (SPTE), provide a clearer estimate of bioaccessibility than organic carbon normalization by serving as a sink for desorbing compound for the length of the extraction. In this way, SPTEs account for all the factors affecting desorption and the resulting interstitial water concentrations, providing estimates of the chemical concentration that will become available for exposure in a given time frame. The utility of SPTEs as an exposure metric has been demonstrated many times in the literature through estimates of bioaccumulation and development of toxicity benchmarks. The simplicity, accuracy, and robust nature of this technique suggests this tool could serve as an ideal means of evaluating exposure and risk of HOCs, and more specifically acutely toxic compounds, such as pyrethroids, during environmental sampling and risk assessments of aquatic sediments. However, the use of this method is limited within the scientific literature and absent from most risk assessment protocols. The reasons for its limited use are linked to poor methodological standardization, an absence of understanding of environmental and methodological variation on estimates of bioaccessibility provided by SPTEs, and only a vague idea of how Tenax extractions relate to other exposure metrics, such as passive samplers. Therefore, the dissertation goals were to: evaluate the effects of variation in the SPTE, specifically the Tenax mass to organic carbon mass (Tenax:OC) ratio, on exposure estimates of pyrethroids (Chapter Two); understand how methodological and environmental variation affect the relation of SPTEs to bioaccessibility represented by desorption of pyrethroids from the labile desorbing fraction (Frap) (Chapter Three); and, determine how bioavailability and bioaccessibility are linked through evaluation of chemical activity expressed as the freely dissolved chemical concentrations provided by SPTEs, passive sampler concentrations, and Frap (Chapter Four). The most variable aspect of the SPTE within the Tenax literature is the Tenax:OC ratio used during 24 h SPTEs. Yet, no study has evaluated how altering this ratio may affect 24 h SPTE concentrations and thus, biological exposure estimates provided by Tenax extractions. Manipulating the Tenax:OC ratio used during 24 h SPTEs of pyrethroids from laboratory-spiked and field-contaminated sediments revealed the effect of this variation was such that Tenax extractable pyrethroid concentrations varied between 0.85 to 3.91-fold between the highest and lowest ratios examined. The results of this experiment suggest most of the variation in toxicological endpoints derived using Tenax extractable concentrations is due to toxicokinetic and toxicodynamic variation in biological responses across sediments and not due to methodological variation of the Tenax extraction (Chapter Two). The utility of the SPTEs as an estimate of exposure is linked to the ability of SPTEs to reflect the chemical concentration that desorbs from sediment. As many factors, such as the organic carbon content, aging time of sediments, and hydrophobicity of the compounds, can impact desorption, understanding how these factors affect the relationship of SPTEs to biological exposure is needed to evaluate the consistency of the Tenax extraction. The relation of SPTE concentrations to Frap was proportional despite changes in organic carbon content of the sediment being extracted, the hydrophobicity of the pyrethroids, or the Tenax mass used during the extraction, such that the SPTE concentration was equal to 1.46 ± 0.03 times the pyrethroid concentration in Frap (Chapter Three). Only the aging time of the pyrethroids in the sediment significantly affected this relationship, as desorption from longer aged sediments slowed, reducing the 24 h SPTE concentration to Frap ratio by -0.0027/d (Chapter Three). The results of Chapters Two and Three demonstrate the consistency of the Tenax extraction as a representation of biological exposure of pyrethroids in sediment. However, other aspects limit the widespread use of the Tenax method, particularly the relation of this technique to more widely accepted bioavailability-based metrics, such as passives samplers. Tenax extractions are often disregarded in favor of passive samplers as the link between bioavailability-based metrics, chemical activity, and exposure is well understood. However, as SPTEs and passive samplers both demonstrate a clear relation to bioaccessibility through estimates of Frap, it was hypothesized that both exposure metrics represent the same chemical fraction of sediment, and as such could be considered complementary tools for evaluating biological exposure through estimates of the freely dissolved interstitial water concentration. This was confirmed when comparisons of the chemical activity expressed as the interstitial water concentration at equilibrium were done using the chemical concentration estimated by Frap, a passive sampler, and SPTEs. Strong linear relationships (p<0.0001) were found among all three metrics, such that Frap, passive sampler, or 24 h SPTE concentrations of pyrethroids from sediment provide comparable estimates of the freely dissolved interstitial water concentration in sediment. Thus, Tenax extractions and passive samplers, which describe the bioaccessible and bioavailable concentrations, respectively, describe the same chemical fraction in sediment; the labile desorbing fraction. This dissertation provides further concrete evidence that the SPTE offers a robust, rapid, and cost-effective means of evaluating exposure of acutely toxic compounds in sediment. With data that link this exposure metric to more widely accepted methods, such as passive samplers, and demonstrate the robust character of the SPTE, the research presented here should further the use of the SPTE within the scientific and risk assessment communities.