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Characterization and Bioremediation Viability of Polycyclic Aromatic Hydrocarbon Contamination in the Banks of the Mahoning RiverBuffone, Steven A. 16 September 2015 (has links)
No description available.
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Mobile Laboratory Measurement of Black Carbon, Particulate Polycyclic Aromatic Hydrocarbons and Other Exhaust Emissions in Mexico CityJiang, Mei 28 March 2005 (has links)
Black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) are two atmospheric pollutants produced by motor vehicles using carbonaceous fuels. As a part of the Mexico City Project, measurements of BC, PPAHs and many other gas- and particle-phase emissions were measured in Mexico City using a mobile laboratory during the Mexico City Metropolitan Area field campaign in April 2003 (MCMA-2003). The main goal of this research is to estimate emissions of BC and particulate PAHs (PPAHs) for Mexico City's vehicle fleet. The emissions of gas-phase pollutants such as carbon monoxide (CO), total nitrogen oxides (NOy) and volatile organic compounds (VOC) are also estimated. The mobile lab has previously been used to chase vehicles and measure their emissions, but analysis has traditionally focused on determining emission factors of individual vehicles associated with specific chasing events. The laboratory continuously samples ambient air from an inlet at the front of the van, and it is always "seeing" exhaust plumes from the vehicles around it while driving through traffic. We have developed an algorithm that automatically identifies the exhaust plume measurement points, which are then used as the basis for calculation of emission factors. In the nearly 90 hours of on-road sampling during the field campaign, we have identified ~30,000 exhaust measurement points. The large sample size enables us to estimate fleet-average emission factors and thus the emission inventory. Motor vehicles are estimated to emit annually 1,960 tons of BC, 56.2 tons of PPAHs, 1,320,000 tons of CO, 125,000 tons of NOy and 2440 tons of VOCs. The spatial and temporal patterns of BC and PPAHs in different locations with in MCMA are also studied. / Master of Science
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Proximity to Potential Sources and Mountain Cold-trapping of Semi-volatile Organic ContaminantsWestgate, John Norman 13 August 2013 (has links)
If sufficiently persistent, semi-volatile organic contaminants (SVOCs) can travel long distances through the atmosphere from their points of release and become concentrated in cold, remote regions. As air is sampled for SVOCs to establish both their presence and the success of emission reduction efforts, it becomes helpful to determine sampling site proximity to sources and the origin of the sampled air masses. Comparing three increasingly sophisticated methods for quantifying source proximity of sampling locations, it was judged necessary to account for the actual history of the sampled air through construction of an airshed, especially if wind is highly directional and population distribution is very non-uniform. The airshed concept was improved upon by introducing a ‘geodesic’ grid of equally spaced cells, rather than a simple latitude/longitude grid, to avoid distortion near Earth’s poles and to allow for the comparison of airshed shapes. Assuming that a perfectly round airshed reveals no information about sources allows the significance of each cell of an airshed to be judged based on its departure from roundness. Combining air-mass histories with a 2 year-long series of SVOC air concentrations at Little Fox Lake in Canada’s Yukon Territory did not identify distinct source regions for most analytes, although γ-hexachlorocyclohexane appears to originate broadly in north-eastern Russia and/or Alaska. Based on this remoteness from sources, the site is judged to be well suited to monitor changes in the hemispheric background concentrations of SVOCs. A model-based exploration revealed wet-gaseous deposition as the dominant process responsible for cold-trapping SVOCs in mountain soils. Such cold trapping is particularly effective if precipitation rate increases with altitude and if temperature differences along the mountain are large. Considerable sensitivity of the modeled extent of cold-trapping to parameters as diverse as scale, mean temperature, atmospheric particle concentration and time relative to emission maxima is consistent with the wide variety of observed enrichment behaviour. Concentration gradients of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in air and soil measured on four Western Canadian mountains with variable distance from sources revealed source proximity as the main driver of concentrations at both the whole-mountain scale and along individual mountain transects.
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Proximity to Potential Sources and Mountain Cold-trapping of Semi-volatile Organic ContaminantsWestgate, John Norman 13 August 2013 (has links)
If sufficiently persistent, semi-volatile organic contaminants (SVOCs) can travel long distances through the atmosphere from their points of release and become concentrated in cold, remote regions. As air is sampled for SVOCs to establish both their presence and the success of emission reduction efforts, it becomes helpful to determine sampling site proximity to sources and the origin of the sampled air masses. Comparing three increasingly sophisticated methods for quantifying source proximity of sampling locations, it was judged necessary to account for the actual history of the sampled air through construction of an airshed, especially if wind is highly directional and population distribution is very non-uniform. The airshed concept was improved upon by introducing a ‘geodesic’ grid of equally spaced cells, rather than a simple latitude/longitude grid, to avoid distortion near Earth’s poles and to allow for the comparison of airshed shapes. Assuming that a perfectly round airshed reveals no information about sources allows the significance of each cell of an airshed to be judged based on its departure from roundness. Combining air-mass histories with a 2 year-long series of SVOC air concentrations at Little Fox Lake in Canada’s Yukon Territory did not identify distinct source regions for most analytes, although γ-hexachlorocyclohexane appears to originate broadly in north-eastern Russia and/or Alaska. Based on this remoteness from sources, the site is judged to be well suited to monitor changes in the hemispheric background concentrations of SVOCs. A model-based exploration revealed wet-gaseous deposition as the dominant process responsible for cold-trapping SVOCs in mountain soils. Such cold trapping is particularly effective if precipitation rate increases with altitude and if temperature differences along the mountain are large. Considerable sensitivity of the modeled extent of cold-trapping to parameters as diverse as scale, mean temperature, atmospheric particle concentration and time relative to emission maxima is consistent with the wide variety of observed enrichment behaviour. Concentration gradients of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in air and soil measured on four Western Canadian mountains with variable distance from sources revealed source proximity as the main driver of concentrations at both the whole-mountain scale and along individual mountain transects.
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Phytoremediation of soil contaminated with petroleum hydrocarbons and trace elementsMarchand, Charlotte 08 1900 (has links)
The rapid urbanization and industrialization has led to an increase of disposal petroleum hydrocarbons (PHC) and trace elements (TE) into the environment. These pollutants are considered as the most toxic contaminants in the world due to their persistence in the environment, and the long range of toxicological effects for living beings when their concentrations exceed critical thresholds.
Recent concerns regarding the environmental contamination have initiated the development of several remediation technologies, including physico-chemical, biological and Dig and Dump approaches. In my thesis, gentle soil remediation options (GRO) were investigated at different scales for the reclamation of PHC and TE co-contaminated soil.
In the first part of my thesis, laboratory experiments were performed to characterize PHC and TE contaminated soil as well as the indigenous microorganisms (bacteria and fungi) present in these contaminated soils. It was found that the studied aged contaminated soil had a negative effect on earthworm’s development and Lepidium sativum biomass. Moreover, a high respiration of microorganisms attributed to the transformation/ mineralization of organic matter or/and organic pollutants was observed. This presence of viable microorganisms suggested an adaptation of microorganisms to the contaminant. Further results showed that the long-term exposure of soil microorganisms to high PHC concentration and the type of isolation culture media did not influence the ability of isolates to effectively degrade PHC. However, phylogenic affiliation had a strong effect on PHC biodegradation.
In the second part of my thesis, preliminary studies in greenhouse trials were performed to investigate the ability of Medicago sativa assisted by compost in the greenhouse aided-phytoremediation of PHC and TE. The results clearly showed that compost amendment into the soil promoted PHC degradation, M. sativa growth and survival, and phytoextraction of TE. Residual risk assessment after the phytoremediation trial also showed a positive effect of compost amendment on plant growth and earthworm development.
Pilot-scale ecopile experiment carried out in the third part of this thesis allow a reduction of up to 80% of PHC and 20% of metals after 17 months.
My thesis showed that alfalfa (M. sativa) and sunflower (Helianthus annus) plants were suitable for phytodegradation of PHC and phytoextraction of TE. The outcomes of my thesis can be extend to other plants and they bring a new level of understanding that can be helpful for further full-scale phytoremediation studies. / L'urbanisation rapide et les activités industrielles ont abouti à la contamination de l’environnement par les hydrocarbures pétroliers (HP) et les éléments traces (ET). Ces composés sont particulièrement toxiques en raison de leur persistance dans l'environnement, et de leurs effets toxicologiques sur les êtres vivants quand les concentrations de ceux-ci dépassent des seuils critiques.
Les préoccupations de plus en plus croissantes sur la contamination de l'environnement ont favorisé le développement de plusieurs technologies de remédiation des sites contaminés par les approches biologiques, physico-chimiques et par l’excavation et l’entreposage. Dans cette thèse, des options douces d'assainissement des sols (ODA) ont été utilisées à différentes échelles pour la remédiation des sols contaminés par des mélanges des HP et des ET.
Dans la première partie de ma thèse, des expériences en laboratoire ont été effectuées dans le but de caractériser les sols contaminés et les micro-organismes autochtones (bactéries et champignons) qu’ils contiennent. Malgré la contamination ancienne du sol, les résultats obtenus montrent des effets négatifs des contaminants sur le développement des lombrics et la biomasse de Lepidium sativum. En outre, une respiration élevée de microorganismes, attribuée à la transformation / minéralisation de la matière organique et / ou des polluants organiques a été observée. Cette présence de micro-organismes viables dans les sols contaminés suggère leur adaptation aux contaminants. Toutefois, d'autres résultats ont montré que l'exposition à long terme des microorganismes du sol à de fortes concentrations en HP et le type de milieu de culture utilisé pour l'isolation n'influencent pas la capacité des isolats microbiens à dégrader efficacement les HP. Cette capacité de biodégradation des HP est liée à la phylogénie des microorganismes.
Dans la deuxième partie de cette thèse, les études préliminaires en serre ont été réalisées dans le but d’évaluer l’efficacité de phytoremédiation en utilisant Medicago sativa assistée par l’ajout du compost. Les résultats ont montré dans cette expérience que l’ajout du compost dans le sol favorise la dégradation des HP, la croissance et la survie de M. sativa, ainsi que la phytoextraction des ET. L’évaluation des risques résiduels après la phytoremédiation a également montré un effet positif de l'amendement du sol en compost sur la croissance des plantes et le développement des lombrics.
L’expérience pilote réalisée sur le terrain dans la troisième partie de ma thèse a permis une réduction de 80% des HP et de 20% des ET après 17 mois.
Ma thèse a démontré que la luzerne (M. sativa) et le tournesol (Helianthus annus) sont des choix judicieux de plantes pour la phytodégradation des HP et pour la phytoextraction des ET. Les résultats qui en résultent sont utiles pour d’autres études de phytoremédiation à grande échelle. / Den snabba urbaniseringen och industrialiseringen har lett till en ökning av petroleumkolväten (PHC) och olika spårämnen (TE) i miljön. Dessa föroreningar anses vara de mest giftiga föroreningarna i världen på grund av att de stannar kvar i miljön samt att de har toxikologisk påverkan på levande varelser.
På senare tid har oron för dessa miljöföroreningar lett till utvecklingen av flera saneringstekniker, såsom fysiska, kemiska och biologiska metoder. I denna avhandling undersöktes enkla marksaneringsalternativ (GRO) på olika nivåer, för återvinning av PHC och TE från förorenad jord.
I den första delen av denna avhandling, utfördes laboratorieförsök för att karakterisera PHC- och TE-förorenad jord samt av de inhemska mikroorganismerna (bakterier och svampar) som förekommer i dessa förorenade jordar. Det konstaterades att den studerade förorenade jorden hade en negativ inverkan på daggmaskars utveckling och biomassan av L. sativum. Dessutom kunde den höga respirationen bland mikroorganismerna tillskrivas omvandlingen och mineraliseringen av organiskt material och/eller de organiska föroreningar som observerades. Denna närvaro av livsdugliga mikroorganismer antydde att mikroorganismerna anpassat sig till föroreningssituationen på platsen. Ytterligare resultat visade dock att den långvariga exponeringen av höga PHC-koncentrationer i isolerade odlingsmedier, för mikroorganismer i jorden, inte påverkade förmågan för dessa att effektivt bryta ned PHC. Dock hade den fylogenetiska tillhörigheten en stark påverkan på bionedbrytning av PHC.
I den andra delen av denna avhandling genomfördes preliminära studier i växthus där förmågan hos M. sativa undersöktes, med hjälp av kompost, gällande den växthusstödda fytosaneringen av PHC och TE. Resultaten visade att inblanding av kompost i jorden främjade nedbrytningen av PHC, tillväxten och överlevnadsgraden av M. sativa och fytoextraktion av Pb. Återstående riskbedömning efter fytosaneringen visade också en positiv effekt, när komposten användes, på växternas tillväxt och daggmaskarnas utveckling.
Ett experiment med eco-bädd utfördes för den tredje delen av avhandlingen. Denna studie visade på en minskning på upp till 80% av PHC och 20% av metallerna.
Denna avhandling visar att M. sativa och H. annus var lämpliga för nedbrytning av PHC och fytoextraktion av Pb och Cu.
Resultaten från denna avhandling förväntas vara användbara för ytterligare studier av fytoremediering i fullskala.
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Analysis of PAH and PCB Emissions from the Combustion of dRDF and the Nondestructive Analysis of Stamp AdhesivesPoslusny, Matthew 05 1900 (has links)
This work includes two unrelated areas of research. The first portion of this work involved combusting densified refuse derived fuel (dRDF) with coal and studying the effect that Ca(0H)2 binder had on reducing polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) emissions. The second area of work was directed at developing nondestructive infrared techniques in order to aid in the analysis of postage stamp adhesives. With Americans generating 150-200 million tons a year of Municipal Solid Waste (MSW) and disposing of nearly ninety percent of it in landfills, it is easy to understand why American landfills are approaching capacity. One alternative to landfilling is to process the MSW into RDF. There are technical and environmental problems associated with RDF. This work provides some answers concerning the amount of PAH and PCB emissions generated via the combustion of RDF with coal. It was found that the Ca(OH)2 binder greatly reduced both the PAH and the PCB emissions. In fact, PAH emissions at the ten-percent level were reduced more by using the binder than by the pollution control equipment. If the Ca(0H)2 binder can reduce not only PAH and PCB emissions, but also other noxious emissions, such as acid gases or dioxin, RDF technology could soon be the answer to the current landfill problems. The second portion of this work focused on developing a method to analyze stamp adhesives nondestructively. Using this method, it was fairly easy to differentiate among the three different types of adhesives that have been used by the United States Postal Service: gum arabic, dextrin, and polyvinyl alcohol. Differences caused by changes in chemicals added to the adhesives were also detected. Also, forgeries were detected with as much success, if not more, than by conventional methods. This work also led to the construction of equipment that allows large samples to be analyzed by reflectance infrared methods.
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Uticaj fizičko-hemijskih svojstava mikroplastike i odabranih perzistentnih organskih polutanata na interakcije u vodenom matriksu / Impact of physicochemical properties of microplastics and selected persistent organic pollutants on interactions in the aqueous matrixLončarski Maja 20 October 2020 (has links)
<p>Mikroplastika je sveprisutna u vodenom ekosistemu pri čemu se često<br />ističe značaj ispitivanja njihovog uticaja na ponašanje drugih jedinjenja u vodi.<br />Pod pojmom mikroplastika podrazumevaju se plastične čestice manje od 5 mm.<br />Imajući u vidu potrebu za unapređenjem znanja o štetnom uticaju mikroplastike<br />u životnoj sredini u ovom radu sproveden je set eksperimenata u kom je ispitivan<br />mehanizam interakcija koje se uspostavljaju prilikom adsorpcije hlorovanih<br />fenola, derivata benzena i policikličnih aromatičnih ugljovodonika na mikroplastici u vodenom matriksu. Kako bi se što detaljnije razumeo uticaj mikroplastike i osobina vodenog matriksa na ponašanje organskih polutanata, laboratorijska ispitivanja su sprovedena u sintetičkom i realnom vodenommatriksu. Takođe je sprovedena optimizacija izolovanja i karakterizacije mikroplastike iz kozmetičkih sredstava u cilju procene uticaja osobina primarne mikroplastike na uspostavljanje interakcija sa organskim polutantima. Na osnovu dobijenih rezultata istraživanja može se zaključiti da se optimalna metoda izolovanja mikroplastike iz kozmetičkih sredstava zasniva na dodatnom tretiranju osušenog materijala 30% vodonik-peroksidom, nakon ekstrakcije sredstva u destilovanoj vodi, u cilju dobijanja čistijih uzoraka mikroplastike. Promena brzine mešanja ima znčajan uticaj na promenu stepena adsorpcije ispitivanih grupa organskih jedinjenja. Uticaj se ogleda u povećanju stepena adsorpcije sa porastom brzine mešanja, a maksimalni procenat adsorpcije postignut je pri brzini mešanja od 150 o/min. Dodatno, disperzija praškastih materijala u vodi nema značajan uticaj na promenu stepena adsorpcije hlorovanih fenola, derivata benzena i policikličnih aromatičnih ugljovodonika na mikroplastici.Ravnotežno stanje između koncentracije hlorovanih fenola, derivata<br />benzena i policikličnih aromatičnih ugljovodonika u vodi i odabranih predstavnika mikroplastike (PEp, PE_PCPs_1, PE_PCPs_2, PEg, PET, PP i PLA) uspostavlja se nakon 24 i 48 h kontakta u zavisnosti od vrste jedinjenja. Na promenu adsorpcionog afiniteta hlorovanih fenola, derivata benzena i policikličnih aromatičnih ugljovodonika prema mikroplastici utiču kako fizičkohemijske osobine jedinjenja tako i karakteristike mikroplastike. Na osnovu kinetičkih eksperimenata, najveći adsorpcioni afinitet ka mikroplastici ispoljili su derivati benzena (qt=103-350 µg/g), dok je najmanji uočen kod hlorovanih fenola (qt=25-225 µg/g). Dobijeni rezultati adsorpcije derivata benzena na ispitivanim česticama mikroplastike takođe su ukazali na veći afinitet ovih jedinjenja ka mikroplastici, u poređenju sa jedinjenjima iz grupe policikličnih aromatičnih ugljovodonika i hlorovanih fenola sličnih logKow vrednosti. Dodatno, uticaj vodenog matriksa na adsorpciju hlorovanih fenola, derivata benzena i policikličnih aromatičnih ugljovodonika na mikroplastici zavisi od same grupe jedinjenja kao i od vrste mikroplastike pri čemu je najmanje izražen u slučaju ispitivanih policikličnih aromatičnih ugljovodonika, a najviše kod hlorovanih fenola.Visoke vrednosti koeficijenta determinacije kinetičkog modela pseudodrugog reda za adsorpciju hlorovanih fenola, derivata benzena i policikličnih aromatičnih ugljovodonika na čestice mikroplastike ukazjuju da je hemisorpcija mogući mehanizam. Pored visokih vrednosti koeficijenata determinacije u slučaju svih odabranih organskih jedninjenja dobijena konstanta brzine drugog reda bila je manja od po četne brzine adsorpcije što ukazuje na znatno brže odvijanje adsorpcije pri kraćim vremenima kontakta (12-24 h) nakon čega je<br />dolazilo do usporavanja procesa adsorpcije.Mehanizam adsorpcije hlorovanih fenola, derivata benzena i policikličnih aromatičnih ugljovodonika ispitivan je primenom Freundlich-ovog, Langmuirovog, Redlich-Peterson-ovog i Dubinine-Radusckevich-evog adsorpcionog modela. Vrednosti Freundlich-ovog eksponenta za adsorpciju hlorovanih fenola, derivata benzena i policikličnih aromatičnih ugljovodonika bile su manje od 1,<br />što ukazuje na to da je slobodna energije adsorpcije na mikroplastci opadala sa povećanjem inicijalne koncetracije ispitivanih polutanata. Vrednosti maksimalnog adsorpcionog kapaciteta dobijene za adsorpcione procese PAH na česticama mikroplastike bile su u opsegu od 29,7-2596,5 µg/g. Visoke vrednosti maksimalnih adsorpcionih kapaciteta dobijene su takođe za adsorpciju derivata benzena na ispitivanim vrstama mikroplastike 39,3-2010,1 µg/g. S druge strane, uočeno je različito adsorpciono ponšanje hlorovanih fenola u zavisnosti od vodenog metriksa u kom su eksperimenti sprovedeni pri čemu su qmax vrednosti iznosile 20,00-205,6 µg/g. Značajan uticaj pH vrednosti vodenog matriksa utvrđen je za adsorpciju hlorovanih fenola na mikroplastici, dok u slučaju derivata benzena i PAH promena pH vrednosti vodenog matriksa nije pokazala značajan uticaj. Rezultati dobijeni za adsorpciju hlorovanih fenola na mikroplastici ukazuju na nižu tendenciju ka formiranju interakcija hlorovanih fenola sa česticama mikroplastike pri pH 4 i pH 10, pri čemu se stepen adsorpcije kretao u opsegu od 8-35% i 15-35%, respektivno, u odnosu na pH 7 (55-65%). Najniži adsorpcioni afinitet uočava se pri adsorpciji ispitivanih grupa jedinjenja na PLA. Može se pretpostaviti da će se organski polutanti, ukoliko ova vrsta mikroplastike dospe u vodene sisteme, slabo vezivati na ovaj materijal pri čemu će značajno manje uticati na njihov trasport kroz životnu sredinu, u odnosu<br />na druge ispitivane vrste mikroplastike. Na osnovu dobijenih rezultata istraživanja može se zaključiti da na adsorpciju ispitivanih grupa organskih jedinjenja i mikroplastike značajan uticaj imaju fizičko-hemijske osobine ispitivanih jedinjenja kao što su kiselinska konstanta, veličina molekula, hidrofobnost, stukturni raspored i dr. Pored toga, karakteristike vodenog matriksa, među kojima je najvažnija pH vrednost, imaju značajan uticaj na adsorpcioni afinitet jedinjenja ka mikroplastici. Dodatno,<br />struktura i poreklo polimera ima veliki uticaj na formiranje interakcija sa<br />ispitivanim grupama organskih polutanata. Dobijeni rezultati takođe ukazuju na<br />nemogućnost određivanje unifomnog mehanizma adsorpcije organskih<br />jedinjenja na česticama mikroplastike u vodi.</p> / <p>Microplastics are ubiquitous in aquatic ecosystems, so it is essential to study their impact on the behaviour of other compounds which are commonly present in water. The term microplastics refers to all plastic particles smaller than 5 mm. In order to address knowledge gaps relating to the potential harmful effects of microplastics in the environment, the experiments conducted during this thesis were designed to investigate the adsorption mechanism of chlorinated phenols, benzene derivatives, and polycyclic aromatic hydrocarbons on microplastics in water. To provide a more detailed understanding of the influence of different water matrices on adsorption properties of microplastics, experiments were conducted in both synthetic and real water matrices. In the course of this work, methods were optimised for the isolation and characterization of microplastifrom personal care products, in order to allow investigation of the influence of the properties of primary microplastics on their interactions with organic pollutants.Base on the obtained results, it can be concluded that the optimal method of isolating microplastics from personal care products is based on treating already dried material with 30% hydrogen peroxide, after extraction of the agent in distilled water, in order to obtain cleaner microplastic samples. The mixing rate was found to have a significant effect on the degree of adsorption of the investigated organic compounds. Increasing the mixing speed led to a higher<br />degree of adsorption, with the maximum adsorption percentage reached at a<br />mixing speed of 150 rpm. In addition, the dispersion of powdered materials in the water had no significant effect on the degree of adsorption of chlorinated phenols, benzene derivatives, and polycyclic aromatic hydrocarbons on microplastics.<br />The adsorption equilibrium between the concentration of chlorinated phenols, benzene derivatives and polycyclic aromatic hydrocarbons in water and selected types of microplastics (PEp, PE_PCPs_1, PE_PCPs_2, PEg, PET, PP, and PLA) was established after 24 and 48 h of contact time, depending on the selected group of organic pollutants. The adsorption affinity of chlorinated phenols, benzene derivatives, and polycyclic aromatic hydrocarbons towards microplastics was influenced by both the physicochemical properties of the compounds and the characteristics of the microplastics. Based on the kinetic experiments, the highest adsorption affinity for microplastics was shown by benzene derivatives (qt=103-350 µg/g), while the lowest was observed during the adsorption of chlorinated phenols (qt=25-225 µg/g). Benzene derivatives showed higher adsorption affinities for the selected microplastic particles than the polycyclic aromatic hydrocarbons and chlorinated phenols which had similar logKow values. The influence of the water matrix on adsorption of chlorinated phenols, benzene derivatives, and polycyclic aromatic hydrocarbons on microplastics depended on the specific functional groups of the investigated compounds as well as on the type of microplastics. Water matrix had little impact on the adsorption of polycyclic aromatic hydrocarbons on microplastics but greatly impacted the adsorption of chlorinated phenols. Fitting the pseudo-second order kinetic model to the adsorption data of chlorinated phenols, benzene derivatives, and polycyclic aromatic hydrocarbons on microplastic particles resulted in high correlation coefficients, indicating that chemisorption is the likely adsorption mechanism. In addition to the high correlation coefficients obtained for all the organic pollutants investigated, the pseudo-second order rate constants obtained were lower than the initiaadsorption rate, indicating significantly faster adsorption at shorter contact times (12-24 h), with adsorption slowing down as equilibrium was reached.The adsorption mechanism of chlorinated phenols, benzene derivatives,<br />and polycyclic aromatic hydrocarbons was investigated using Freundlich,Langmuir, Redlich-Peterson, Dubinine-Radusckevich, and Temkin adsorption models. The Freundlich exponent values for the adsorption of chlorinated phenols, benzene derivatives, and polycyclic aromatic hydrocarbons were less than 1 which indicates that the free energy of adsorption of these compounds on microplastics decreases as the initial concentration increases. The maximum adsorption capacities of PAHs on microplastic particles were in the range of 29.7-2596.5 µg/g. High maximum adsorption capacities were also obtained for the adsorption of benzene derivatives on the tested types of microplastics: 39.3-2010.1 µg/g. The chlorinated phenols behaved differently, and were more effected by the water matrix, with qmax values in the range 20.00-205.6 µg/g. The pH of the water matrix was found to have a significant effect on the adsorption of chlorinated phenols on microplastics, whereas in the case of benzene derivatives and polycyclic aromatic hydrocarbons, the degree of<br />adsorption was largely independent of the water pH. For the adsorption of chlorinated phenols on microplastics, neutral pH conditions resulted in the greatest degrees of adsorption (55-65% at pH 7), while adsorption was inhibited under acidic (8-35% at pH 4) and basic (15-35% at pH 10) conditions. The microplastic type with the lowest observed adsorption affinities was PLA. It can be thus be assumed that in the event that this type of microplastic enters water systems, organic pollutants will only adsorb weakly to this material, such that it will have significantly less impact on the transport of the se compounds through the environment, than the other tested types of microplastics. The results obtained in this research demonstrate that the adsorption of the selected groups of organic pollutants on the microplastics investigated is significantly controlled by the physicochemical properties of the tested compounds, such as the dissociation constant, molecule size, hydrophobicity,<br />structural properties, etc. In addition, the characteristics of the water matrix play an important role in controlling adsorption of organic pollutants on microplastic, especially the water pH. In addition, the structure and aging of the polymers had a major influence on their interactions with the selected organic pollutants. The obtained results also demonstrate the difficulty in determining a uniform mechanism of adsorption between the various organic compounds and microplastic particles in water.</p>
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Photo-Induced Toxicity and Toxicokinetics of Single Compounds and Mixtures of Polycyclic Aromatic Hydrocarbons in Zebrafish and Sheepshead MinnowWillis, Alison Micha 05 July 2013 (has links)
No description available.
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A modular synthesis of processable and thermally stable semi-fluorinated aryl ether polymers via step-growth polymerization of fluoroalkenesShelar, Ketki Eknath 13 May 2022 (has links)
Tailored fluoropolymers remain the leading choice for a wide variety of advanced high-performance applications, including electronic/optical and energy conversion, owing to their unique blend of complementary high-performance properties. Amorphous semi-fluorinated polymers exhibit improved solubility and melt processability when compared to traditional perfluoropolymers. A leading class of semi-fluorinated aryl ether polymers includes perfluorocyclobutyl (PFCB), perfluorocycloalkenyl (PFCA), and fluoroarylene vinylene ether (FAVE) polymers. Monomers containing aromatic trifluorovinyl ethers (TFVE) are used to synthesize PFCB polymers via radical-mediated [2+2] cyclodimerization. On the other hand, FAVE and PFCA polymers are polymerized via base-mediated nucleophilic addition/elimination of bisphenols with TFVE monomers and decafluorocyclohexene respectively. The use of different monomer cores (aromatic, aliphatic, contorted, and renewable) should help to develop general structure/property relationships for this versatile and expanding approach to semi-fluorinated aryl ether polymers. The enchainment of polycyclic aromatic hydrocarbon (PAH) cores with functional fluorocarbon groups (or segments) recently afforded a new class of semi- fluorinated polymers in the continuing quest for novel organic materials for potential applications in optoelectronic, gas-separation, and advanced composites. Chapter 2 details the incorporation of commercially available acenaphthenequinone was achieved to afford PFCB aryl ether polymers with excellent solubility, high thermal stability, and film-forming capability. Chapter 3 represents base-promoted nucleophilic addition/elimination of commercial bisphenols with TFVE-triphenylene monomers affording FAVE aryl ether polymers possessing excellent solution processability, high thermal stability and photostability. In addition, triphenylene-enchained FAVE polymers exhibit extreme thermal-oxidative photostability and emit blue light after heating in air at 250 °C for 24 h. Further, time-dependent density functional theory (TD-DFT) computations were performed to understand electronic polymer structures. In one case, post-polymerization Scholl coupling converted the central triphenylene core to afford a hexabenzocoronene containing semi-fluorinated polymer with new optoelectronic properties. Chapter 4 demonstrates synthesis and characterization of renewable semi-fluorinated polymers obtained using aliphatic diol isosorbide. This renewable diol readily polymerizes with bis-TFVE derivatives of bisphenol A and 6F to provide high molecular weight thermoplastics exhibiting excellent solubility and tough, transparent film-forming capability. Finally, Chapter 5 presents synthesis of TFVE enchained corannulene which gave blue-light emission and outstanding processability. Synthesis and characterization, including the new materials' optical, thermal, and electronic properties, is presented.
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Selective Retention of β-Carbolines and 7,12-Dimethylbenz[<i>a</i>]anthracene in the Brain : Role of Neuromelanin and Cytochrome P450 for ToxicityÖstergren, Anna January 2005 (has links)
<p>The ß-carbolines norharman and harman structurally resemble the synthetic compound 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) that is known for its ability to damage neuromelanin-containing dopaminergic neurons of the substantia nigra and thereby induce parkinsonism. MPTP is, however, not normally present in the environment whereas the ß-carbolines are present in cooked food and tobacco smoke. </p><p>In this thesis it was demonstrated that norharman and harman had affinity to melanin and were retained in neuromelanin-containing neurons of frogs up to 30 days post-injection (the longest survival time examined). It was also demonstrated that norharman induced neurodegeneration, activation of glia cells and motor impairment in mice. Furthermore, this compound induced ER stress and cell death in PC12 cells. An in vitro model of dopamine melanin-loaded PC12 cells was developed in order to study the effect of melanin on norharman-induced toxicity. In this model, melanin seemed to attenuate toxicity induced by low concentrations of norharman. After exposure to the highest concentration of norharman, melanin clusters were disaggregated and there was an increased expression of stress proteins and caspases-3, known to be involved in apoptosis.</p><p>The polycyclic aromatic hydrocarbon, 7,12-dimethylbenz[<i>a</i>]anthracene was demonstrated to have a CYP1A1-dependent localization in endothelial cells in the choroid plexus, in the veins in the leptomeninges and in the cerebral veins of mice pre-treated with CYP1-inducers. </p><p>These results demonstrate that the distribution of environmental compounds could be influenced by the presence of neuromelanin and expression of CYP enzymes in the brain and that norharman may induce neurotoxic effects in vivo and in vitro.</p>
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