No description available.

The determination of carbon monoxide is also possible by trapping CO on preconditioned molecular sieve and thermal desorption. Analysis in this case is performed by gas chromatography/mass spectroscopy, although the trapping technique is applicable to other suitable GC techniques.

Metabolomics is a powerful science that can be applied for the discovery of disease biomarkers, and investigation of altered metabolomes due to abiotic and biotic perturbations. This dissertation is focused on untargeted metabolomic applications to investigate fungal metabolite alterations associated with pathogenicity, fungal disease propagations, and symbiosis. This dissertation employs qualitative analysis of metabolite mixtures using HS-SPME coupled GC-MS and TMS derivatization followed by GC-MS analytical platforms. In the first study, we discovered a biomarker combination to diagnose fungal soft tissue disease in sweet potato at an early stage of disease propagation. We used an HS-SPME GC-MS untargeted metabolomics workflow to analyze the VOC associated with Rhizopus stolonifer infected and healthy sweet potatoes in situ and simulated warehouse environments. A single combination of 4 biomarkers was able to diagnose R. stolonifer fungal soft tissue disease (AUC = 0.980, 95% C.I. 0.937-1) and the early stage of the fungal soft rot disease (AUC = 0.999, 95% C.I. 0.978-1). We were able to detect the biomarkers: 1- propanol, ethyl alcohol, ethyl propionate and 3-methyl-3- buten-1-ol during disease progression in a simulated warehouse environment. Therefore, this study shows the feasibility of early diagnosis of fungal soft tissue disease by a real-time screening of volatile profiles of sweet potato in post-harvest storage. When considering the study of a particular species metabolome, it is crucial to develop a metabolite extraction protocol. In the second study, the performance of the six different metabolite extraction solvents mixtures was tested with the preferred mix being: butanol:methanol:water (2:1:1, v/v at -20 °C) which was used as a single solvent mix to extract both polar and relatively non-polar metabolites simultaneously in a single extraction step. The Macrophomina phaseolina fungal metabolome was investigated using the solvent mix. Finally, fungal mutualism was studied using untargeted metabolomics. Most often mycorrhizal metabolomics workflows are based on analyzing the Arbuscular Mycorrhizae colonized root metabolome. But here, we used hyphal materials to examine the mutualistic symbiotic association of the AM fungi. All untargeted metabolomic studies included chemometric data analysis and specific biomarkers and or metabolites were determined using multivariate statistics or prediction model building and validating.

<p dir="ltr">In this era of changing global climate and globalization, the intricate relationships between non-native organisms and their impacts on forest health are of paramount concern. Bark and ambrosia beetles are diverse groups of insects that are among the most intercepted insects at international ports of entry. Once established, these insects can vector pathogens and disrupt functional forest dynamics. Bark and ambrosia beetles are known to attack various tree species, including black walnut (<i>Juglans nigra</i>), a valuable timer and nut-producing tree native to Eastern North America. Non-native woodboring beetles provide unique opportunities for ecological studies and pest management. This research investigates the chemical ecology and microbial dynamics in black walnut ecosystems to fill critical knowledge gaps and address the pressing issues surrounding forest health and sustainable management.</p><p dir="ltr">In Chapter 1, I review the current literature describing the use of semiochemicals in bark and ambrosia beetle management, non-native scolytines as vectors of phytopathogens, and the use of nematodes as natural antagonists of fungal pathogens in trees.</p><p dir="ltr">In Chapter 2, I aim to identify attractant and repellent semiochemicals for the ambrosia beetle <i>Anisandrus maiche</i>, which is a first step in developing effective management strategies for this species. I found that conophthorin and verbenone are strong repellents and that this beetle is attracted to ethanol in a dose-dependent manner.</p><p dir="ltr">In Chapter 3, I tested the hypothesis that <i>Anisandrus maiche </i>will be influenced by volatiles of its nutritional fungal symbiont, <i>Ambrosiella cleistominuta,</i> and that these compounds may synergize with ethanol. I identified seven unique compounds from the fungus and two fungal alcohols in the field. I found isobutyl alcohol to repel <i>A. maiche </i>while isoamyl alcohol has seasonal effects on <i>A. maiche </i>capture when paired with ethanol.</p><p dir="ltr">In Chapter 4, I aimed to characterize the assemblage of microorganisms residing on two non-native ambrosia beetles across diverse forest types. I tested the hypothesis that forest stand diversity and management regimes would affect the assemblage of microorganisms of ambrosia beetles. I found forest type influences the abundance of fungi and bacteria on <i>A. maiche </i>and <i>Xylosandrus crassiusculus</i> and that both beetle species transport genera of pathogenic fungi.</p><p dir="ltr">In Chapter 5, I test the hypothesis that inoculation with <i>Geosmithia morbida </i>alters the volatile profile of black walnut. I found one isolate of <i>G. morbida </i>induced changes in the volatile profile of black walnut bark and identified the compounds that changed relative to the control trees.</p><p dir="ltr">In Chapter 6, I tested the hypothesis that free-living fungivorous nematodes can modulate Thousand Cankers Disease severity. I found two genera of nematodes <i>Panagrolaimus </i>and <i>Aphelenchoides </i>to orient towards agents of the TCD system in Y-tube bioassays. <i>Aphelenchoides </i>sp. that were exposed to <i>G. morbida </i>grown on agar media augmented with black walnut bark extract significantly reduced <i>G. morbida </i>cankers in black walnut seedlings. This research has important implications for the management of TCD.</p><p dir="ltr">In Chapter 7, I summarize results from each of research chapter and discuss future research needs and directions to continue development of the knowledge surrounding chemical ecology and microbial dynamics of non-native scolytine beetles.</p>

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Die vorliegende Arbeit ist Teil einer Mutter -Kind -Kohortenstudie LiNA (Lebensstil und Umweltfaktoren und deren Einfluss auf das Neugeborenen-Allergierisiko), deren Ziel es ist, komplexe Expositionen gegenüber verschiedener Umweltbelastungen, insbesondere Chemikalien und deren Auswirkungen auf den Organismus zu betrachten. Viele Forschungsergebnisse lassen vermuten, dass gerade die Schwangerschaft ein sensibles Zeitfenster darstellt, in dem die pränatale Entwicklung des Kindes prädisponierend für das Auftreten bestimmter allergischer Krankheiten sein kann. Die Aufgabe dieser Arbeit bestand in einer epidemiologischen Untersuchung des Einflusses bestimmter Renovierungsmaßnahmen wie Malerarbeiten, Verlegen eines neuen Fußbodens und Aufstellen neuer Möbel während der Schwangerschaft bzw. im 1. Lebensjahr des Kindes auf die Ausbildung respiratorischer Erkrankungen des einjährigen Kindes. • Das Verlegen von Fußboden, sowie Malerarbeiten während der Schwangerschaft zeigten eine Risikoerhöhung an einer obstruktiven Bronchitis im ersten Lebensjahr zu erkranken (OR 4.39, 95% CI 1.01–19.05; OR 5.46, 95% CI 1.09–27.20). • Das Verlegen von neuem Fußboden während der gesamten Schwangerschaft korrelierte als einzige Renovierungsaktivität signifikant positiv mit „behandlungsbedürftigem Giemen“ im ersten Lebensjahr (OR= 5.20, 95% CI 1.8– 15.2). • Insbesondere das Verlegen von Laminatboden (OR= 4.46, 95% CI 1.01–19.63), Teppichboden (OR= 4.57 CI 1.14–18.39) und PVC Boden (OR= 24.7, 95% CI 2.18– 280.39) zeigte eine Risikoerhöhung an „behandlungsbedürftigem Giemen“ zu erkranken. • Das Verlegen neuer Fußböden mit und ohne Gebrauch von Klebstoffen war advers mit dem Auftreten von behandlungsbedürftigem Giemen assoziiert. • Kindern mit atopischer Familienanamnese haben ein fünffaches Risiko an „behandlungspflichtigem Giemen“ zu erkranken (OR= 5.68, 95% CI 1.17–27.53), wenn während der Schwangerschaft neuer Fussboden verlegt wurde. • Interessanterweise gab es keine signifikante Assoziation zwischen dem Verlegen eines neuen Fußbodenbelags im ersten Lebensjahr und dem Entstehen von „behandlungspflichtigem Giemen“. Darüber hinaus verglichen wir die Renovierungsmaßnahmen mit den gemessenen VOC-Werten aus der elterlichen Wohnung, um einen möglichen Zusammenhang zwischen Renovierung und Schadstoffbelastung herstellen zu können. • Die Konzentrationen von 6 VOC (Styrol, Isopropylbenzol, Ethylbenzol, Dekan, Undekan, Tridekan) waren in den Haushalten mit neuem Fußbodenbelag in der Schwangerschaft und im ersten Lebensjahr signifikant höher, als in den Haushalten, in denen nie renoviert wurde. Eine Konzentrationserhöhung ergab sich zudem wenn Kleber beim Verlegen des Fußbodens verwendet wurde. • Wir fanden 14 VOC (Propylbenzol, o- Xylol, m+ p-Xylol, 4-Ethyltoluol, 3-Ethyltoluol, 2- Ethyltoluol, 1,2,3-Trimethylbenzol, 1,2,4-Trimethylbenzol, 1,3,5-Trimethylbenzol, Oktan, Nonan, 3-Heptanon, Tetrahydrofuran, 1-Butanol), deren Konzentrationen nach dem Verkleben des Fußbodens signifikant höher waren. • Als einziges aromatisches VOC blieb Styrol die Verbindung, welche nach dem Verlegen von neuem Fußboden in der Schwangerschaft eine signifikante Konzentrationserhöhung im ersten Lebensjahr aufwies. Schließlich wurde nach einer Korrelation zwischen den gefundenen VOC-Werten und dem Auft reten von respi rator i s chen Er k rankungen innerha l b einer Querschnittspopulation der einjährigen Kinder gesucht. • Für 6 VOC (Styrol, Ethylbenzol, Tridekan, o-Xylol, Oktan, 1-Butanol)c konnten wir eine positive Assoziation mit „behandlungsbedürftigem Giemen“ nachweisen. • Eine Belastung mit Styrol in der Schwangerschaft und im ersten Lebensjahr war mit einem erhöhten Risiko an „behandlungspflichtigem Giemen“ zu erkranken, assoziiert (OR= 1.5, 95% CI 1.07–2.09). Vorangegangene Studien konnten bisher nur zeigen, dass eine Exposition mit VOC zu unmittelbaren Atemwegssymptomen bei Kindern führen kann. Diese Studie belegt den schädigenden Einfluss einer Belastung während der Schwangerschaft auf die respiratorische Gesundheit des Kindes im ersten Lebensjahr. Neuer Fußbodenbelag im Wohnumfeld von Schwangeren erhöht deutlich das Risiko von Kleinkindern an obstruktiven Atemwegssymptomen zu erkranken. Unsere Studie leistet hier einen wichtigen Beitrag zur Prävention umweltassoziierter Erkrankungen. Es ist deshalb von großer Bedeutung, Schwangere über potentielle pränatale Gesundheitsrisiken für ihr Kind aufzuklären. Demnach sollte eine offizielle Empfehlung ausgesprochen werden, auf aufwendige Renovierungsarbeiten während der Schwangerschaft und vor allem auf das Verlegen von neuem Fußboden zu verzichten. Dadurch könnten ca. 20.000 Fälle von behandlungspflichtigem Giemen im Kleinkindalter vermieden werden.:Inhaltsverzeichnis…..…………………………………………………………………………...2 Abkürzungsverzeichnis………………………………………………………………………...3 1.Einleitung……………………………………………………………………………………....4 1.1. Die LiNA-Studie……….…………………………………..…………………………........4 1.2. Der Einfluss der Innenraumluft auf die kindliche Gesundheit…...…………………....6 1.3. Flüchtige organische Verbindungen als Bestandteil der Innenraumluft..……...........7 1.4. Gesundheitliche Effekte durch VOC..………...……………………………………........7 1.5. Innenraumbelastung durch VOC und Auswirkungen auf das Immunsystem…........9 1.6. Relevanz des Expositionszeitpunktes..……………………………………………........9 1.7. Schlussfolgerungen und weiterer Forschungsbedarf….……………………….........10 2. Publikation………………………………………………………………………………......12 3. Zusammenfassung……..………………………...……………………………………......21 4. Literaturverzeichnis…………………………………………………………………….......24 5. Anlagen………………………………….……………………………….....……………….27 Erklärung über eigenständige Abfassung der Arbeit… ………………………………….28 Spezifizierung des eigenen Beitrags………………………………………………………...29 Lebenslauf……………………………………………………………………………………...33 Danksagung……………………………………………………………………………………35

Emissions from natural ecosystems, broadly classified as biogenic volatile organic compounds (BVOCs), contribute 90\% to the VOC budget. Individual BVOCs vary widely in their reaction rates with atmospheric oxidants, making their atmospheric impact highly dependent on VOC composition. Their emissions are also dependent on vegetative make up and a number of meteorological and ecological variables. However, the ecological and physical drivers of their emissions is becoming more variable in a changing climate, leading to greater uncertainties in models. Increasing the monitoring of individual compounds can improve our understanding of the drivers of these emissions and the impact of individual chemical species on atmospheric composition. Improved understanding of BVOC composition can better emission models and, SOA and ozone formation predictions. To study the atmospheric impacts and physical drivers of BVOCs, a GC-FID was adapted for automated hourly sampling and analysis. The details of the hardware and software used for the system are described in detail to enable future long-term BVOC measurements in additional locations. The instrument was deployed at a measurement tower in a forest in central Virginia for year-round collection of BVOC concentrations. Using two years of collected hourly data, this work assesses the chemical impacts of individual BVOCs on time scales ranging from hour to year. This work identifies the importance of both concentration and chemical structure in determining atmospheric impacts. Additionally, seasonality in the concentration of some biogenic species has large implications for atmospheric reactivity in the warmest months of the year, particularly ozone reactivity. Using ecological and meteorological data collected at the site in conjunction with the BVOC data, the drivers of BVOC concentrations and their seasonality are identified. Comparison between this data and current models, reveal important deviations which may lead to large modeled uncertainties. Furthermore, the collected data has been made publicly available to aid in future research regarding BVOCs. / Doctor of Philosophy / The earth hosts a number of sources of atmospheric emissions. These range from human-driven sources such as vehicles and factories, to natural sources such as trees and grass. The content of these emissions, amongst others, become a part of a large reactor (the atmosphere), that interact with each other. The interaction of these emissions with atmospheric oxidants forms a gas (ozone) with implications for human and ecosystem health, and secondary organic aerosol (the leading component to smog). However, the extent to which these emissions react with atmospheric oxidants is largely dependent on the structure of individual compounds. A major focus of this dissertation is to show that compounds with reactive structures can have a large impact on atmospheric composition, and that the quantity of emissions can be as important as compound structure. Understanding the impact of individual compounds in the atmosphere requires improved measurement techniques, capable of detecting the compounds of interest over long time periods. Therefore, another focus of this work was the adaptation and deployment of an instrument capable of detecting some of the most reactive species in the atmosphere, volatile organic compounds emitted from forests. The instrument deployed in this work was a gas chromatography flame ionization detector (GC-FID), which detects compounds largely composed of carbon and hydrogen. The instrument was adapted to run automatically through the development of an electronics box and software program interfaced with the GC-FID. Following development, the instrument was deployed to a remote forest research site for two years. The data collected from this work was used to determine the impact of individual compounds on atmospheric composition. Findings from this work could be used to improve a range of atmospheric models. Small changes in emissions (human or plant) contribute to the total VOC budget which can have large implications for the formation of ozone and SOA. Therefore, increased understanding of the BVOC concentrations and emission driver will aid in predicting these atmospheric components.

Heterogeneous reactions between mineral dust aerosols and gas phase volatile organic compounds have the potential to impact important atmospheric chemical processes. However, little is known about the uptake and reactivity of volatile organic compounds on particulates found in the environment. A Knudsen cell was designed and constructed for providing precise measurement of reaction probabilities within these systems. The instrument was validated through a series of experiments. After validating the Knudsen cell against several key benchmarks, the instrument was used to measure the uptake coefficient for ethanol on particulate silicon dioxide. The uptake coefficient of ethanol on silicon dioxide, a common compound in mineral dust aerosols, was determined to be 7 x 10-7. Therefore, uptake of ethanol on silicon dioxide would be competitive with the loss of other volatile organic compounds on silicon dioxide, which show similar rates of uptake. The Knudsen cell was validated and measured the uptake of ethanol on silicon dioxide, and future work with the Knudsen cell will study the uptake of chemical warfare agent simulants on metal oxides. / Master of Science

Biogenic volatile organic compounds (BVOCs) are naturally occurring organic compounds emitted by plants, trees, and ecosystems, exerting a profound influence on the Earth's atmosphere, air quality, climate, and ecosystem dynamics. This research project aims to advance our understanding of BVOC emissions and their implications through a comprehensive and multi-faceted investigation. We investigate the dynamics of BVOCs in the atmosphere through three key objectives. First, we introduce a novel enriching inlet that uses selective permeation to preconcentrate reactive organic gases in small sample flows for atmospheric gas sampling, enhancing the sensitivity and detection limits of analytical instruments. Enrichments between 4640% and 111% were measured for major reactive atmospheric gases at ultra low flow rates and roughly several hundred percent for ambient samples at moderately low flow rates. Second, we constrain light-dependency in BVOC emissions models by comparing modeled and long-term observed BVOC concentrations measured at a mid-canopy monitoring site in a southeastern US forest. The Model of Emissions of Gases and Aerosols from Nature (MEGAN) and the Framework for 0-D Atmospheric Modeling (F0AM) were utilized to simulate emissions and chemical transformations, respectively to disentangle the time- and species-specificity of light dependency for various BVOC (α-pinene, camphene, and α-fenchene are completely light-independent and limonene, β-thujene, sabinene, and γ-terpinene are seasonally light-dependent). Finally, we examine these models deeper to investigate uncertainties and highlight current limitations due to variability in planetary boundary layer height (PBLH) datasets. We highlight the significance of simultaneous PBLH and BVOC measurements for improving the accuracy of BVOC concentration models. We show that a lack of co-located measurements is a large source of uncertainty in modeling BVOC concentrations. The successful completion of these objectives contributes to a better understanding of the complex interactions between BVOC emissions and atmospheric chemistry. / Doctor of Philosophy / Biogenic volatile organic compounds (BVOCs) are natural chemicals released by plants, trees, and ecosystems. They interact with combustion emissions such as those from vehicles (nitrous oxides or NOX species) in the presence of light to produce secondary pollutants such as ozone and particulate matter which significantly affect human health, Earth's atmosphere, air quality, climate, and ecosystems. This research aims to deepen our understanding of BVOC emissions and their effects through a detailed study of measurement and modeling techniques used to study BVOC. We accomplish this via three main goals. First, we introduce a new method to enhance the detection of reactive gases in small air samples, improving the sensitivity of currently available analytical instruments. This method showed significant improvements in detecting key atmospheric gases. Second, we examine how BVOC emissions depend on light by comparing models with long-term observations from a forest in the southeastern US. We used two models, Model of Emissions of Gases and Aerosols from Nature (MEGAN) and Framework for 0-D Atmospheric Modeling (F0AM), to simulate emissions and chemical changes, revealing that some BVOC emissions are completely light-independent processes, while others depend on the season. Finally, we examine these models deeper to investigate the uncertainties due to variability in planetary boundary layer height (PBLH) datasets (the layer of air closest to the Earth's surface where pollutants are concentrated). We show that a lack of BVOC and PBLH measurements made at the same location is a large source of uncertainty in modeling BVOC concentrations. Achieving these goals will enhance our understanding of the complex interactions between BVOC emissions and atmospheric chemistry.

Yes / A simple method is reported for the estimation of in vivo air-tissue partition coefficients of VOCs and of in vitro blood-tissue partition coefficients for volatile organic compounds and other compounds. Linear free energy relationships for tissues such as brain, muscle, liver, lung, kidney, heart, skin and fat are available and once the Abraham descriptors are known for a compound, no more than simple arithmetic is required to estimate air-tissue and blood-tissue partitions.