• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • 2
  • Tagged with
  • 5
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Investigating the Mutagenicity of Polycyclic Aromatic Compounds from the Athabasca Oil Sands Region in River Otters and a Mammalian Cell Line

Gyasi, Helina 27 May 2022 (has links)
Mining operations have led to an increase in polycyclic aromatic compound (PAC) concentrations in the Alberta oil sands area. However, the toxicity of most PACs and PAC mixtures is not well characterized. Some PACs and PAC mixtures are known to be mutagenic, though there is limited research on the genotoxicity of PACs from the Alberta oil sands to wildlife. This thesis tested the hypothesis that anthropogenic sources of PACs from the Alberta oil sands are mutagenic to wildlife. The objectives were: 1) to determine whether wildlife with increased exposure to PACs had increased mutations, and 2) to determine whether an anthropogenic source of PACs is mutagenic in a controlled lab setting. For the first objective, we used a single-molecule polymerase chain reaction (SM-PCR) assay to detect microsatellite mutations in river otters with differing liver tissue PAC concentrations in the Athabasca oil sand region (AOSR; Alberta, Canada). For objective two, an in vitro mammalian mutagenicity assay with the FE1 MutaMouse epithelial cell line (FE1) was used to determine the mutagenic potential of a bitumen extraction by-product, tailings pond bitumen. We found that PAC exposure in the AOSR was positively correlated with elevated microsatellite mutations in river otters. From the in vitro study, tailings pond bitumen extracts did not induce lacZ mutations in the FE1 cells. Differences in detection methods between the two assays and PAC profiles between the otter tissue and tailings pond bitumen are suspected reasons for contradictory results. Further investigation of the different sources and PAC profiles within the AOSR environment and wildlife food web will provide insights on what types of PACs are mutagenic. Cytotoxicity, observed following exposure to tailings pond bitumen extracts, also suggests other toxicity pathways should be considered when investigating the toxicity of bitumen from the AOSR. Overall, this thesis provided data on the potential mutagenicity of PACs in the AOSR, which can be used to elucidate potential molecular mechanisms of toxicity in wildlife exposed to oil processing contaminants.
2

Polycyclic Aromatic Hydrocarbon Characterization in Otter Creek, Northwest Ohio

Bobak, Deanna M. 14 June 2010 (has links)
No description available.
3

Hidrocarbonetos polic?clicos arom?ticos em sedimentos de fundo do estu?rio do rio Potengi, regi?o da grande Natal (RN): implica??es ambientais

Queiroz, Maria Sara Maia de 07 February 2011 (has links)
Made available in DSpace on 2014-12-17T14:08:43Z (GMT). No. of bitstreams: 1 MariaSMQ_DISSERT_1-36.pdf: 5283210 bytes, checksum: e75f1aa1d6f8e40607338226667f1b0d (MD5) Previous issue date: 2011-02-07 / Estuaries are environments prone to the input of chemical pollutants of various kinds and origins, including polycyclic aromatic hydrocarbons (PAHs). Anthropogenic PAHs may have two possible sources: pyrolytic (with four or more aromatic rings and low degree of alkylation) and petrogenic (with two and three aromatic rings and high degree of alkylation). This study aimed to evaluate the levels, distribution and possible sources of polycyclic aromatic hydrocarbons in the estuary of the Potengi river, Natal, Brazil. Samples of bottom sediments were collected in the final 12 km of the estuary until its mouth to the sea, where the urbanization of the Great Natal is more concentrated. Sampling was performed on 12 cross sections, with three stations each, totaling 36 samples, identified as T1 to T36. The non alkylated and alkylated PAHs were analyzed by gas chromatography coupled to mass spectrometry (GC / MS). PAHs were detected in all 36 stations with total concentration on each varying 174-109407 ng g-1. These values are comparable to those of several estuarine regions worldwide with high anthropogenic influence, suggesting the record of diffuse contamination installed in the estuary. PAHs profiles were similar for most stations. In 32 of the 36 stations, low molecular weight PAHs (with 2 and 3 ring: naphthalene, phenanthrene and their alkylated homologues) prevailed, which ranged from 54% to 100% of the total PAH, indicating that leaks, spills and combustion fuels are the dominant source of PAH pollution in the estuary. The level of contamination by PAHs in most stations suggests that there is potential risk of occasional adverse biological effects, but in some stations adverse impacts on the biota may occur frequently. The diagnostic ratios could differentiate sources of PAHs in sediments of the estuary, which were divided into three groups: petrogenic, pyrolytic and mixing of sources. The urban concentration of the Great Natal and the various industrial activities associated with it can be blamed as potential sources of PAHs in bottom sediments of the estuary studied. The data presented highlight the need to control the causes of existing pollution in the estuary / Os estu?rios s?o ambientes prop?cios ao aporte de poluentes qu?micos de diversas naturezas e origens, incluindo Hidrocarbonetos Polic?clicos Arom?ticos (HPA). Os HPA antr?picos s?o de duas fontes poss?veis: pirol?tica (com quatro ou mais an?is arom?ticos e baixo grau de alquila??o) e petrog?nica (com dois e tr?s an?is arom?ticos e alto grau de alquila??o). O presente trabalho teve como objetivo avaliar os n?veis, distribui??o e poss?veis fontes de Hidrocarbonetos Polic?clicos Arom?ticos no estu?rio do rio Potengi, Natal-RN. Amostras de sedimentos de fundo foram coletadas nos 12 km finais do estu?rio at? a sua foz, onde a urbaniza??o da Grande Natal ? mais concentrada. A amostragem foi realizada em 12 se??es transversais, com tr?s esta??es em cada uma, totalizando 36 amostras, identificadas de T1 a T36. Os HPA alquilados e n?o alquilados foram analisados por cromatografia gasosa acoplada a um detector seletivo de massas (CG/EM). Foram detectados HPA em todas as 36 esta??es, com concentra??o total em cada uma variando de 174 a 109407 ng g-1. Esses valores s?o compar?veis aos de v?rias regi?es estuarinas mundiais com grande influ?ncia antr?pica, o que sugere o registro de contamina??es difusas instaladas no estu?rio. O perfil de HPA foi similar para a maioria das esta??es. Em 32 das 36 esta??es predominaram HPA de baixo peso molecular (com 2 e 3 an?is: naftaleno, fenantreno e seus hom?logos alquilados), que variaram de 54% a 100% em rela??o ao total de HPA, indicando que vazamentos, derramamentos e queima de combust?veis s?o a fonte dominante de polui??o por HPA no estu?rio. O n?vel de contamina??o por HPA na maioria das esta??es sugere que h? risco potencial de ocasionais efeitos biol?gicos adversos serem observados, por?m em algumas esta??es se confirmam que impactos adversos sobre a biota ocorrem com freq??ncia. As raz?es diagn?sticas permitiram diferenciar as fontes de HPA nos sedimentos do estu?rio, que foram divididos em tr?s grupos: sedimentos com padr?es de introdu??o de hidrocarbonetos petrog?nicos, pirol?ticos e de mistura de fontes. A concentra??o urbana da Grande Natal e as atividades industriais diversas a ela associadas podem ser responsabilizadas como fontes potenciais dos HPA nos sedimentos de fundo do estu?rio estudado. Os dados apresentados evidenciam a necessidade de se controlar as causas da polui??o existente no estu?rio
4

Caracteriza??o geol?gica, geoqu?mica e geocronol?gica da su?te plut?nica enoproteroz?ica da regi?o de Serrinha, por??o centro-leste do maci?o S?o Jos? de Campestre, sudeste do RN

Dias, Luiz Gustavo da Silveira 31 August 2006 (has links)
Made available in DSpace on 2015-03-13T17:08:39Z (GMT). No. of bitstreams: 1 LuizGSD_ate_cap6.pdf: 3498562 bytes, checksum: 2d2d95d878c0320cd578c1fd98d02cfe (MD5) Previous issue date: 2006-08-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The of Serrinha plutonic suite, northeastern portion of the Borborema Province (NE Brazil), is characterized by a voluminous and diversified magmatism of Neoproterozoic age, intrusive in the Archean to Paleoproterozoic gneissic-migmatitic basement of the S?o Jos? de Campestre massif. Field relations and petrographic and geochemical data allowed us to individualize different lithologic types among this plutonic suite, which is represented by intermediate to mafic enclaves, porphyritic diorites, porphyritic granitoids, porphyritic granodiorites, microporphyritic granites and dykes/sheets of microgranite. The intermediate-to-mafic enclaves occur associated with porphyritic granitoids, showing mixture textures. The porphyrytic diorites occur as isolated bodies, generally associated with intermediate-to-mafic enclaves and locally as enclaves within porphyritic granites. The granodiorites represent mixing between an intermediate to mafic magma with an acidic one. The micropophyritic granites occur as isolated small bodies, generally deformed, while the microgranite dykes/sheets crosscut all the previous granitoids. A U-Pb zircon age of 576 + 3 Ma was obtained for the Serrinha granite. This age is interpreted as age of the peak of the regional ductile deformational event (D3) and of the associated the E-W Rio Jacu shear zone, which control the emplacement of the Neoproterozoic syntectonic plutons. The porphyrytic granitoids show monzogranitic composition, transitional between peraluminous and metaluminous types, typically of the high potassium subalkaline-calc-alkaline series. The intermediate-to-mafic enclaves present vary from quartz diorite to tonalite/granodiorite, with metaluminous, shoshonitic affinity. The diorites are generally quartz-monzodiorite in composition, with metaluminous, subalkaline affinity. They display coarse-grained, inequigranular, porphyrytic texture, with predominance of plagioclase phenocrystals immersed in a matrix composed of biotite and pyroxenes. The microporphyrytic granites are essentially monzogranites of fine- to medium-grained texture, whereas microgranite dikes/sheets varying from monzogranites to syenogranites, with fine to media texture, equigranular. The diversified magmatism occurring at a relatively small surface associated with shear zones, suggests lithospheric dimensions for such structures, with magma extractions from different depths within the lower crust and upper mantle. The geological, geochemical and geochronological characteristics of the Serrinha plutonic suite suggest a pos-collisional geodynamic context for the Neoproterozoic magmatism. Thermobarometric data show emplacement conditions in the range 5-6 kbar (AlTamphibole) and 730-740?C (plagioclase-amphibole) for the porphyrytic granitoids (Serrinha body) and the intermediate-to-mafic enclaves / A su?te plut?nica da regi?o de Serrinha, localizada no extremo nordeste da Prov?ncia Borborema (NE do Brasil), caracteriza-se por um volumoso e diversificado magmatismo de idade neoproteroz?ica, intrusivo no substrato gn?issico-migmat?tico, de idade arqueana a paleoproteroz?ica, do Maci?o S?o Jos? de Campestre. Rela??es de campo, dados petrogr?ficos e geoqu?micos permitiram individualizar os diferentes tipos litol?gicos desta su?te plut?nica, que s?o representados por encraves intermedi?rios a m?ficos, rochas dior?ticas porfir?ticas, granit?ides porfir?ticos, granodioritos porfir?ticos, granitos microporfir?ticos e diques/sheets microgran?ticos. Os encraves intermedi?rios a m?ficos ocorrem, principalmente, associados aos granit?ides porfir?ticos, exibindo fei??es de mistura. Os dioritos porfir?ticos ocorrem como corpos isolados, associados com encraves intermedi?rios a m?ficos, e localmente como encraves nos granitos porfir?ticos. Os granodioritos representam um f?cies t?pico de mistura entre um magma intermedi?rio a m?fico, dior?tico, e outro ?cido, granitico. Os granitos microporfir?ticos apresentam-se como pequenos corpos isolados, geralmente deformados. Os diques e sheets microgran?ticos s?o tardios na seq??ncia magm?tica da ?rea estudada, com rela??es intrusivas nas demais unidades magm?ticas. Uma idada U-Pb em zirc?o de 576 + 3 Ma foi obtida para o Granito Serrinha, que ocorre controlado por uma zona de cisalhamento de dire??o geral E-W (Zona de Cisalhamento Rio Jacu). Tendo em vista o car?ter sintect?nico desse pl?ton, essa idade marca a sua coloca??o e o pico da deforma??o D3 associada. Este evento ? respons?vel pela atual arquitetura estrutural da ?rea mapeada, com gera??o da tect?nica ranscorrente/distensional impressa nas zonas de cisalhamento que controlam o alojamento dos pl?tons neoproteroz?icos. Os granit?ides porfir?ticos apresentam composi??o predominantemente monzogran?tica, apresentando caracter?sticas transicionais entre peraluminosos e metaluminosos, tipicamente de afinidade subalcalina - c?lcio-alcalina de alto K. Os encraves intermedi?rios a m?ficos variam de quartzo dioritos a tonalitos/granodioritos, com textura faner?tica fina a m?dia. S?o rochas metaluminosas de afinidade shoshon?tica. As rochas dior?ticas porfir?ticas s?o principalmente quartzo monzodioritos, com textura inequigranular porfir?tica, com predom?nio de fenocristais de plagiocl?sio imersos numa matriz composta por biotita e pirox?nios. S?o rochas metaluminosas, de afinidade subalcalina m?fica. Os granitos microporfir?ticos s?o essencialmente monzogranitos de textura fina a m?dia, inequigranular, e os diques e sheetsmicrogran?ticos apresentam composi??o variando de monzogranitos a sienogranitos, com textura fina, equigranular. Apesar da pouca quantidade de dados, essas rochas apresentam caracter?sticas de afinidade geoqu?mica com a s?rie c?lcio-alcalina de alto K. O diversificado magmatismo ocorrendo em uma superf?cie relativamente pequena, associado a zonas de cisalhamento, apontam dimens?es litosf?ricas para essas estruturas, com extra??o de magmas a partir de diferentes n?veis da crosta e do manto superior. As caracter?sticas geol?gicas, geoqu?micas e geocronol?gicas da su?te plut?nica Neoproteroz?ica da regi?o de Serrinha sugerem um contexto geodin?mico p?s-colisional para a coloca??o dos corpos estudados ao final da orog?nese Neoproteroz?ica. Dados termobarom?tricos apontam condi??es P-T da ordem de 5-6 kbar (AlT-anfib?lio) e 730-740?C (plagiocl?sio-anfib?lio) para a coloca??o dos granit?ides porfir?ticos e encraves intermedi?rios a m?ficos associados
5

Hidrocarbonetos polic?clicos arom?ticos no meio ambiente: diferencia??o de fontes em sedimentos e metab?litos em bile de peixes

Meniconi, Maria de F?tima Guadalupe 30 March 2007 (has links)
Made available in DSpace on 2014-12-17T15:42:31Z (GMT). No. of bitstreams: 1 MariaFGM.pdf: 2684798 bytes, checksum: 4d672e17bab00bdd5d88eb70b9c57edf (MD5) Previous issue date: 2007-03-30 / Petr?leo Brasileiro SA - PETROBRAS / Many studies on environmental ecosystems quality related to polycyclic aromatic hydrocarbons (PAH) have been carried out routinely due to their ubiquotus presence worldwide and to their potential toxicity after its biotransformation. PAH may be introduced into the environmet by natural and anthropogenic processes from direct runoff and discharges and indirect atmospheric deposition. Sources of naturally occurring PAHs include natural fires, natural oil seepage and recent biological or diagenetic processes. Anthropogenic sources of PAHs, acute or chronic, are combustion of organic matter (petroleum, coal, wood), waste and releases/spills of petroleum and derivatives (river runoff, sewage outfalls, maritime transport, pipelines). Besides the co-existence of multiples sources of PAH in the environmental samples, these compounds are subject to many processes that lead to geochemical fates (physical-chemical transformation, biodegradation and photo-oxidation), which leads to an alteration of their composition. All these facts make the identification of the hydrocarbons sources, if petrogenic, pyrolytic or natural, a challenge. One of the objectives of this study is to establish tools to identify the origin of hydrocarbons in environmental samples. PAH diagnostic ratios and PAH principal component analysis were tested on a critical area: Guanabara Bay sediments. Guanabara Bay is located in a complex urban area of Rio de Janeiro with a high anthropogenic influence, being an endpoint of chronic pollution from the Greater Rio and it was the scenario of an acute event of oil release in January 2000. It were quantified 38 compounds, parental and alkylated PAH, in 21 sediment samples collected in two surveys: 2000 and 2003. The PAH levels varied from 400 to 58439 ng g-1. Both tested techniques for origin identification of hydrocarbons have shown their applicability, being able to discriminate the PAH sources for the majority of the samples analysed. The bay sediments were separated into two big clusters: sediments with a clear pattern of petrogenic introduction of hydrocarbons (from intertidal area) and sediments with combustion characteristics (from subtidal region). Only a minority of the samples could not display a clear contribution of petrogenic or pyrolytic input. The diagnostic ratios that have exhibited high ability to distinguish combustion- and petroleum-derived PAH inputs for Guanabara Bay sediments were Phenanthrene+Anthracene/(Phenanthrene+Anthracene+C1Phenanthrene); Fluorantene/(Fluorantene+Pyrene); Σ (other 3-6 ring PAHs)/ Σ (5 alkylated PAH series). The PCA results prooved to be a useful tool for PAH source identification in the environment, corroborating the diagnostic indexes. In relation to the temporal evaluation carried out in this study, it was not verified significant changes on the class of predominant source of the samples. This result indicates that the hydrocarbons present in the Guanabara Bay sediments are mainly related to the long-term anthropogenic input and not directly related to acute events such as the oil spill of January 2000. This findings were similar to various international estuarine sites. Finally, this work had a complementary objective of evaluating the level of hydrocarbons exposure of the aquatic organisms of Guanabara Bay. It was a preliminary study in which a quantification of 12 individual biliar metabolites of PAH was performed in four demersal fish representing three different families. The analysed metabolites were 1-hydroxynaphtalene, 2-hidroxinaphtalene, 1hydroxyphenanthrene, 9-hydroxyphenanthrene, 2-hydroxyphenanthrene, 1hydroxypyrene, 3-hidroxibiphenil, 3- hydroxyphenanthrene, 1-hydroxychrysene, 9hydroxyfluorene, 4-hydroxyphenanthrene, 3-hydroxybenz(a)pyrene. The metabolites concentrations were found to be high, ranging from 13 to 177 ?g g-1, however they were similar to worldwide regions under high anthropogenic input. Besides the metabolites established by the used protocol, it was possible to verified high concentrations of three other compounds not yet reported in the literature. They were related to pyrolytic PAH contribution to Guanabara Bay aquatic biota: 1-hydroxypyrine and 3-hydroxybenz(a)pyrine isomers / In?meros estudos da qualidade de ecossistemas naturais em rela??o a contamina??o de hidrocarbonetos polic?ciclos arom?ticos (HPA) t?m sido desenvolvidos continuadamente face a sua presen?a ub?quoa em todo o planeta e ao seu potencial t?xico ap?s a biotransforma??o. A introdu??o dos HPA no meio ambiente pode ocorrer atrav?s de processos naturais e antropog?nicos, atrav?s de despejos e/ou drenagens e deposi??o atmosf?rica indireta. Fontes naturais de HPA incluem queimadas naturais, exsuda??es de ?leo e processos biog?nicos recentes. Fontes antropog?nicas de HPA, advindas de eventos cr?nicos ou agudos, s?o a combust?o incompleta de ?leo combust?vel automotivo e industrial, a queima intencional de madeira e planta??es, os despejos dom?sticos e industriais, as drenagens pluviais urbanas, os efluentes da ind?stria petrol?fera, os derrames acidentais de ?leo e derivados. Al?m da coexist?ncia de m?ltiplas fontes destes hidrocarbonetos nas amostras ambientais, os HPA est?o sujeitos a v?rios processos geoqu?micos que conduzem ? altera??o de sua composi??o qu?mica ao longo do tempo, tornando a identifica??o das fontes contaminantes, se petrog?nica, pirol?tica ou natural, um verdadeiro desafio. Desta forma, um dos objetivos deste estudo foi estabelecer ferramentas que possibilitem a determina??o das fontes de hidrocarbonetos no meio ambiente. Foram utilizadas raz?es diagn?sticas e an?lise de componentes principais de HPA, tendo sido quantificados 38 compostos, incluindo os HPA parentais e alquilados, em 21 amostras de sedimento da Ba?a de Guanabara, coletadas nos anos de 2000 e 2003. A Ba?a de Guanabara ? um ecossistema estuarino com elevada influ?ncia antropog?nica, que recebe polui??o cr?nica da regi?o metropolitana do Rio de Janeiro e que foi cen?rio de um derrame de ?leo em janeiro de 2000. As concentra??es de HPA nos sedimentos estudados apresentaram-se na faixa de 400 a 58439 ng g-1. Ambas as t?cnicas de diferencia??o de fontes de HPA testadas, raz?es diagn?sticas e an?lise de componentes principais, demonstraram sua aplicabilidade, permitindo a diferencia??o das fontes de HPA para a maioria dos sedimentos da ba?a, que foram divididos em dois grandes grupos: sedimentos com padr?es de introdu??o de hidrocarbonetos predominantemente petrog?nicos e sedimentos com caracter?sticas de combust?o. Apenas uma minoria de amostras n?o apresentou com nitidez a natureza de sua contamina??o. As raz?es que apresentaram maior capacidade em diferenciar as fontes de HPA foram Fluoranteno / (Fluoranteno + Pireno), (Fenantreno + Antraceno) / (Fenantreno + Antraceno + C1Fenantreno) e o ?ndice pirol?tico, Σ (HPA parentais de 3-6 an?is) /Σ (5 s?ries de HPA alquilados). Na avalia??o temporal realizada neste estudo n?o foram verificadas varia??es significativas na natureza das fontes contaminantes predominantes na ba?a, revelando que os hidrocarbonetos presentes est?o correlacionados principalmente com os aportes cr?nicos e n?o diretamente com eventos agudos como o derrame de ?leo ocorrido em janeiro de 2000. Este estudo teve como segundo objetivo a avalia??o preliminar do n?vel de exposi??o a que os organismos aqu?ticos da Ba?a de Guanabara est?o submetidos, atrav?s da quantifica??o de 12 metab?litos individuais de HPA presentes em bile de peixe de quatro esp?cies demersais representativas de tr?s fam?lias diferentes. Os metab?litos analisados foram 1-hidroxinaftaleno, 1-hidroxifenantreno, 9hidroxifenantreno, 2-hidroxinaftaleno, 2-hidroxifenantreno, 1-hidroxipireno, 3hidroxibifenila, 3-hidroxifenantreno, 1-hidroxicriseno, 9-hidroxifluoreno, 4hidroxifenantreno, 3-hidroxibenzo(a)pireno. As concentra??es encontradas nas esp?cies de peixes analisadas mostraram-se elevadas, na faixa de 13 a 177 ?g g1, por?m similares ?s encontradas em algumas regi?es de grande influ?ncia antropog?nica, tanto no Brasil quanto no exterior. Al?m dos metab?litos estabelecidos pela metodologia utilizada, foi poss?vel quantificar tr?s compostos, ainda n?o reportados na literatura, em concentra??es relevantes. Estes metab?litos, relacionados a contribui??o pirol?tica de HPA aos organismos aqu?ticos da Ba?a de Guanabara, s?o is?meros de 1-hidroxipireno e de 3-hidroxibenzo(a)pireno

Page generated in 0.0526 seconds