Theoretical studies of pi-pi interactions on several dimers of curved polycyclic aromatic systems have been carried out. In the first part, dispersion corrected density functional theory methods (DC-DFT) were used to evaluate the basis set superposition errors (BSSE) in dispersion interactions of the corannulene dimer, and the accuracy of the calculations using DC-DFT methods was compared with high level benchmark calculations. In these calculations, Grimme’s B97D DC-DFT method provided reasonably accurate results with the benchmark calculations. In addition, BSSE obtained with the B97D method along with cc-pVQZ basis set was negligible. Furthermore, a series of calculations were carried out to obtain the pi-pi interaction energy and most stable conformation for the sumanene dimer system. In these calculations, Grimme’s B97D method was used. The potential energy minimum of the sumanene dimer was determined as the concave-convex stacked arrangement with one monomer unit rotated to 60°. The binding energy of the dimer was found to be 19.34 kcal/mol with a 3.72 angstrom distance between two monomer units. Dimers of three different heterosumanenes along with the parent sumanene were also studied. In this set of calculations, two different concave-convex dimer motifs were chosen, eclipsed and staggered (60° rotated). For all the heterosumanenes, as well as the parent sumanene, the staggered conformation is the most stable geometry. The parent sumanene had the highest binding energy. The –NH substituted sumanene produced the second highest binding energy, while the –O analog was the weakest bonded dimer. Finally, dispersion calculations were carried out for the planar aromatic compound of triphenylene. The pi-system of the dimer was distorted by rotating one monomer unit around the principle axis and parallel displacing one monomer unit relative to the other one. Among the rotational dimers, the 39° rotated dimer was the minimum energy conformation. Interaction energy of that dimer was 14.42 kcal/mol with 3.40 angstrom separation between monomers at the B97D/cc-pVQZ level. The parallel displaced minimum energy dimer has a binding energy about 1.0 kcal/mol smaller than the rotational minimum energy geometry.

No description available.

No description available.

No description available.

Los ambientes costeros mundiales están experimentando un incremento de presión antrópica, que incluye el vertido de desechos industriales y urbanos (muchos de ellos sin ningún tratamiento previo), el aumento de concentraciones de sustancias perjudiciales, los dragados periódicos en los puertos, la ocupación de terrenos intermareales y submareales, entre otros. Entre los compuestos potencialmente contaminantes se encuentran los Hidrocarburos Aromáticos Policíclicos (PAHs, del inglés, Polycyclic aromatic hydrocarbons). Se conocen más de 1000 PAHs, pero a nivel ambiental, sólo un pequeño grupo de estos compuestos adquiere importancia. Los PAHs son tóxicos, persistentes, bioacumulables y tienen la capacidad de ser transportados a través del aire y depositados a largas distancias, causando efectos negativos sobre la salud y el medio ambiente tanto cerca como lejos de su fuente emisora; por esto, comúnmente son incluidos dentro de la categoría de compuestos orgánicos persistentes (COPs). A pesar de que pueden tener origen natural, se considera que la principal fuente de liberación de los PAHs en el medio ambiente son las actividades antropogénicas. Frente a este problema, el objetivo general del presente trabajo de tesis doctoral es estudiar, monitorear e integrar el conocimiento del estado de impacto, flujo y transferencia de PAHs a los compartimentos bióticos. Para ello se obtuvieron muestras de sedimentos superficiales y moluscos bivalvos autóctonos (mejillín, Brachidontes rodriguezii) en diversos sitios de muestreo del Estuario de Bahía Blanca, en las cuales se analizó la presencia de 17 PAHs de interés toxicológico-ambiental. Los resultados obtenidos mostraron que los PAHs se acumulan tanto en sedimentos como en bivalvos para el área de estudio. Las concentraciones halladas permitieron clasificar la zona con niveles moderados de contaminación en relación a otros sitios costeros similares alrededor del mundo. Los máximos valores de PAHs para ambas matrices fueron registrados en inmediaciones del área portuaria industrial, mostrando una tendencia general decreciente a medida que aumentó la distancia a los sitios industriales o más densamente poblados. Por último, se identificaron orígenes mixtos de PAHs para ambas matrices, destacándose los procesos pirolíticos por sobre los petrógenicos. / Global coastal environments are supporting an increased human pressure, including industrial and urban discharges (many of them without adequate treatment), increased concentrations of hazardous substances, periodic dredging in ports, and occupation of intertidal and subtidal lands, among others. Polycyclic Aromatic Hydrocarbons (PAHs) are a large group of compounds (more than 1000), but only a small group of these compounds are of environmental importance. PAHs are a unique class of persistent organic pollutants (POPs) due to their persistence, toxicity, ability to bioaccumulate, long-range transport properties, and adverse effects on environmental and human health. Anthropogenic activities are generally considered the major source of PAHs release into the environment, even though they may have natural origins. In view of this, the main objective of this Ph. D. Thesis is to study, monitor and integrate knowledge of the state of impact, flow and transfer of PAHs to biotic compartments. Following the mentioned objective, surface sediment samples and native bivalves (Mussel, Brachidontes rodriguezii) were collected from the Bahía Blanca Estuary and the presences of 17 PAHs were analyzed. The results showed that PAHs accumulates in both sediments and bivalves within the study area. The concentrations found allowed to classify the area as with moderate levels of contamination in relation to other similar coastal sites around the world. The maximum levels of PAHs were found in the vicinity of the port-industrial area and concentrations of PAHs appeared to decrease as the distance from the urban/industrial core increased. Finally, in both sediment and mussel, mixed PAHs sources were identified, with a slight imposition of pyrolytic over the petrogenic inputs.

Sample preparation via supercritical fluid extraction (SFE) has been increasingly used to determine polynuclear aromatic hydrocarbons (P AHs) in environmental samples. As an alternative sample preparation technique, SFE offers the distinct advantages of greatly reduced sample preparation time, concentrated analyte ready for assay, and comparable extraction efficiency to conventional liquid extraction. Supercritical carbon dioxide is the most widely used SFE fluid. Compared to the other supercritical fluids, carbon dioxide has several advantages: non-flammable, low cost, low toxicity, and low critical parameters. Sixteen P AHs were extracted from dry Chesapeake bay marine sediment using two-step experimental conditions where step 1 was designed to extract the more volatile P AHs and used 100% CO2 and step 2 incorporated parameters for the removal and trapping of the less volatile P AHs with 10% acetone modified supercritical CO2. The final two-step extraction method arrived at exhibited no statistical difference from a previous interlaboratory round robin Soxhlet method on the same matrix in terms of P AH recovery. Recovery from dry marine sediment was compared with the recovery from wet marine sediment. The wet marine sediment was made from existing dry marine sediment by the addition of distilled water. Two methods were used to produce the wet matrix: (1) water added directly to the matrix in the extraction vessel and (2) water added to the matrix and mechanically homogenized. The presence of drying agent and the degree of water homogeneity in the wet matrix influenced the P AH recovery. Statistical analysis indicated that the level of water in the matrix had a significant effect on the recoveries of 13 out of 16 PAHs. In addition, one-step extraction conditions were studied employing the same marine sediment on two different supercritical fluid extractors. However, one-step extraction conditions did not yield comparable results to those of the two-step procedure. The final developed two-step extraction conditions were applied to the southern branch of the Elizabeth river sediment which had a high content of incurred elementary sulfur. / Master of Science

In 1990, creosote contamination was discovered at the location of a railroad tie treatment facility active in the 1950s until 1973. In 1997, a phytoremediation field study was implemented with the planting of 1,026 hybrid poplar trees and 36 cells of vegetated and unvegetated grass and legume treatments. The hybrid poplar tree phytoremediation system was designed to control infiltration and groundwater flow and enhance subsurface remediation. The grass phytoremediation system was designed to control erosion and enhance surface soil remediation. The overall objectives of this study were to: (1) assess the extent of subsurface remediation, (2) determine the mechanisms of remediation attributable to the hybrid poplar tree phytoremediation system and microbial degradation, (3) assess the effects of the grass phytoremediation system on surface soil remediation, and (4) determine the mechanisms of surface soil remediation resulting from the grass phytoremediation system. / Master of Science

Em regiões altamente contaminadas como a região da Baixada Santista, é importante estabelecer metas para a recuperação do ambiente. Apesar da ausência da contaminação ser a meta ideal, as implicações e os custos associados a esse objetivo, demanda o estabelecimento de metas de recuperação realistas em relação aos contaminantes presentes na região. Com o objetivo de caracterizar valores de referência de qualidade de sedimentos para compostos orgânicos na região da Baixada Santista, o Canal de Bertioga foi escolhido como local de referência por ser uma região sem fontes industrais ou outras fontes pontuais relativas aos compostos analisados. Amostras de água, sedimento e ostras foram coletadas e os hidrocarbonetos policíclicos aromáticos (PAHs), bifenilos policlorados (PCBs) e pesticidas organoclorados (OCPs) foram determinados por técnicas cromatográficas. A avaliação dos resultados de análises de PAHs, permite afirmar com alguma segurança, que os valores da somatória de PAHs das amostras sedimentos são, na sua grande maioria, inferiores a 1.000 µg/kg, não superando 1.600 µg/kg, concentrações abaixo dos limites estabelecidos na Resolução CONAMA 344/04 e abaixo dos valores que possam causar algum efeito adverso à biota, conforme valores descritos na literatura. Resultados de análise de PCBs, OCPs, compostos fenólicos e compostos orgânicos voláteis (VOCs) em amostras de sedimento, indicaram concentrações destes compostos abaixo dos limites de quantificação, exceto DDE (5,30 g/kg) e HCB (2,34 g/kg), que foram detectados em apenas um ii sítio de amostragem. Não houve evidências de possíveis fontes de emissão próximas à região de referência para PCBs, OCPs, compostos fenólicos e VOCs. Finalizando, espera-se que os resultados obtidos neste estudo possam fornecer subsídios para futuramente estabelecer uma área de referência para qualidade de sedimento na região da Baixada Santista, ou ainda serem utilizados em conjunto com as avaliações de contaminantes inorgânicos, testes ecotoxicológicos e indicadores biológicos, como ferramenta para avaliação da qualidade de sedimento e/ou para a classificação de material a ser dragado na região da Baixada Santista. / In highly contaminated places like Baixada Santista region, it is important to establish goals for cleaning the environment. Although the absence of contamination would be the ideal goal, the implications and costs related to this goal, demand the establishment of realistic recovery goals for the contaminants presents in the region. Aiming to characterize sediment quality reference values for organic compounds in Baixada Santista region, Bertioga´s Channel was chosen as reference site because there is no direct industrial sources related to the compounds of interest in that region. Water, sediment and oister samples were collected and polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorinated pesticides (OCPs) were determined by chromatographic techniques. From the PAHs results evaluation, is possible to conclude with some degree of confidence, that the sum of PAHs of sediment samples are in the majority lower than 1,000 µg/kg and not higher than 1,600 µg/kg, and these values are below the regulated value (CONAMA 344/04) and lower than those values that may cause any adverse effects for the biota as indicated in the literature. Results of PCBs, OCPs, phenols and VOCs analysis in sediment samples, were below the quantitation limits of the specific methods, except for DDE (5.30 µg/kg) and HCB (2.34 µg/kg) each, detected only in one sampling site. There was no evidence of possible emission source near the reference site for PCBs, OCPs, phenolic compounds and VOCs. Finally, the results obtained in this study may be used as subsidy for the establishment of a reference area for sediment quality in the Baixada Santista region, or still be used together with inorganic contamints, ecotoxicological and biological indicators evaluations as tool for the sediment quality evaluation and/or for dredged material classification in the Baixada Santista region. For the compounds not detected, the suggestion is to use the quantitation limits as the reference value.

Em regiões altamente contaminadas como a região da Baixada Santista, é importante estabelecer metas para a recuperação do ambiente. Apesar da ausência da contaminação ser a meta ideal, as implicações e os custos associados a esse objetivo, demanda o estabelecimento de metas de recuperação realistas em relação aos contaminantes presentes na região. Com o objetivo de caracterizar valores de referência de qualidade de sedimentos para compostos orgânicos na região da Baixada Santista, o Canal de Bertioga foi escolhido como local de referência por ser uma região sem fontes industrais ou outras fontes pontuais relativas aos compostos analisados. Amostras de água, sedimento e ostras foram coletadas e os hidrocarbonetos policíclicos aromáticos (PAHs), bifenilos policlorados (PCBs) e pesticidas organoclorados (OCPs) foram determinados por técnicas cromatográficas. A avaliação dos resultados de análises de PAHs, permite afirmar com alguma segurança, que os valores da somatória de PAHs das amostras sedimentos são, na sua grande maioria, inferiores a 1.000 µg/kg, não superando 1.600 µg/kg, concentrações abaixo dos limites estabelecidos na Resolução CONAMA 344/04 e abaixo dos valores que possam causar algum efeito adverso à biota, conforme valores descritos na literatura. Resultados de análise de PCBs, OCPs, compostos fenólicos e compostos orgânicos voláteis (VOCs) em amostras de sedimento, indicaram concentrações destes compostos abaixo dos limites de quantificação, exceto DDE (5,30 g/kg) e HCB (2,34 g/kg), que foram detectados em apenas um ii sítio de amostragem. Não houve evidências de possíveis fontes de emissão próximas à região de referência para PCBs, OCPs, compostos fenólicos e VOCs. Finalizando, espera-se que os resultados obtidos neste estudo possam fornecer subsídios para futuramente estabelecer uma área de referência para qualidade de sedimento na região da Baixada Santista, ou ainda serem utilizados em conjunto com as avaliações de contaminantes inorgânicos, testes ecotoxicológicos e indicadores biológicos, como ferramenta para avaliação da qualidade de sedimento e/ou para a classificação de material a ser dragado na região da Baixada Santista. / In highly contaminated places like Baixada Santista region, it is important to establish goals for cleaning the environment. Although the absence of contamination would be the ideal goal, the implications and costs related to this goal, demand the establishment of realistic recovery goals for the contaminants presents in the region. Aiming to characterize sediment quality reference values for organic compounds in Baixada Santista region, Bertioga´s Channel was chosen as reference site because there is no direct industrial sources related to the compounds of interest in that region. Water, sediment and oister samples were collected and polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorinated pesticides (OCPs) were determined by chromatographic techniques. From the PAHs results evaluation, is possible to conclude with some degree of confidence, that the sum of PAHs of sediment samples are in the majority lower than 1,000 µg/kg and not higher than 1,600 µg/kg, and these values are below the regulated value (CONAMA 344/04) and lower than those values that may cause any adverse effects for the biota as indicated in the literature. Results of PCBs, OCPs, phenols and VOCs analysis in sediment samples, were below the quantitation limits of the specific methods, except for DDE (5.30 µg/kg) and HCB (2.34 µg/kg) each, detected only in one sampling site. There was no evidence of possible emission source near the reference site for PCBs, OCPs, phenolic compounds and VOCs. Finally, the results obtained in this study may be used as subsidy for the establishment of a reference area for sediment quality in the Baixada Santista region, or still be used together with inorganic contamints, ecotoxicological and biological indicators evaluations as tool for the sediment quality evaluation and/or for dredged material classification in the Baixada Santista region. For the compounds not detected, the suggestion is to use the quantitation limits as the reference value.

La pollution de l'eau est l'une des menaces écologiques les plus sérieuses au niveau des pays industrialisés et des pays en cours de développement. Les polluants sont rejetés directement ou indirectement dans les ressources en eau telles que les rivières, les lacs, les aquifères et les eaux côtières sans prétraitement approprié ; transformant ainsi nos systèmes aquatiques en un dépotoir fortement pollué par des contaminants toxiques et persistants tels que les contaminants organiques. Les hydrocarbures Aromatiques Polycycliques (HAPs) et les pesticides sont parmi les polluants organiques les plus périlleux que l'on retrouve à l’état de traces dans les milieux aquatiques. Pour cette raison, leur analyse nécessite une procédure d'extraction suivie de méthodes analytiques très sensibles et spécifiques. Dans ce contexte, le travail de cette thèse a porté en premier lieu sur le développement de deux méthodes analytiques distinctes. La première a été consacrée à l'extraction et à l'analyse des 16 HAPs prioritaires classés par l’agence de protection de l’environnement (EPA) dans. Dans cette méthode, nous nous sommes concentrés sur l'optimisation et la validation des paramètres de la spectrométrie de masse en tandem (MS / MS) afin de réduire le bruit de fond. La deuxième méthode était dédiée à l'analyse de quarante-huit pesticides dans l'eau. Dans cette méthode, les paramètres de la micro-extraction sur phase solide (SPME) et de la chromatographie en phase gazeuse couplée à la spectrométrie de masse en tandem GC-MS / MS ont été optimisés et validés. Les deux méthodes se sont révélées très sensibles, précises et sélectives pour l'analyse de ces deux familles de contaminants organiques. La deuxième partie de cette thèse était dirigée sur l'évaluation de la qualité de l'eau le long du bassin versant de la rivière Abou Ali en termes de contamination par les HAPs et les pesticides. Pour ce faire, les méthodes précédemment développées et optimisées ont été utilisées pour l'analyse. Les résultats obtenus pour les échantillons d'eau de surface ont révélés une contamination considérable par les HAPs et les pesticides à différents endroits le long du bassin versant. Cependant, pour les échantillons d'eau souterraine, aucune ou très faible concentration de HAPs et de pesticides n'a été détectée. Cette étude est la première de son genre concernant l'analyse des HAPs et des pesticides dans la zone étudiée. Elle donne un aperçu global de la qualité de l'eau le long du bassin versant et insiste sur l'importance de réaliser des mesures continues afin d'avoir une base de données complète non seulement pour la zone d'étude ou le Liban nord mais pour toutes les régions du territoire libanais. / Water pollution is one of the most thoughtful ecological threat imperiling the industrial and developing countries. Pollutants are released directly or indirectly into water resources such as rivers, lakes, aquifers and coastline waters without any suitable pre-treatment; thus transforming our aquatic systems into a dumpsite heavily polluted with toxic and persistent contaminants such as organic contaminants. Polycyclic Aromatics Hydrocarbons (PAHs) and pesticides are among the most perilous organic pollutants that are found in trace levels in aquatic environments. For this reason, their analysis requires an extraction procedure followed by highly sensitive and specific analytical methods. In this context, this work has focused, as a first step, on the development of two separate analytical methods. The first one was dedicated to the extraction and analysis of the 16 priority PAHs in water, listed by the environmental protection agency (EPA). In this method, we have focused on the optimization and validation of tandem mass spectrometry (MS/MS) parameters in order to reduce background noise. The second method was for the analysis of 48 pesticides in water where the solid-phase micro-extraction (SPME) and gas chromatography tandem mass-spectrometry GC-MS/MS parameters were optimized and validated. Both methods were found to be highly sensitive, precise and selective for the analysis of these two families of organic contaminants. As for the second part of this work, the assessment of the water quality along the watershed of Abou Ali River, in terms of its contamination by PAHs and pesticides, was performed. For this aim, the previously developed and optimized methods were used for the analysis. The results obtained for surface water samples revealed a considerable contamination by PAHs and pesticides in different locations along the watershed. However, for groundwater samples no or very low concentrations of PAHs and pesticides were detected. This study is the first of its kind concerning the analysis of PAHs and pesticides in the studied area. It provided an overview of the water quality along the watershed and stressed on the importance to do ongoing measurements in order to have a complete database not only for the studied area or the North of Lebanon, but for all the regions in the Lebanese territory.