Capping is typically used to control contaminant release from the underlying sediments. However, the presence of conventional caps often eliminates or slows natural degradation that might otherwise occur at the surface sediment. This is primarily due to the development of reducing conditions within the sediment that discourage hydrocarbon degradation. The objective of this study was to develop a novel active capping method, an electrode enhanced cap, to manipulate the redox potential to produce conditions more favorable for hydrocarbon degradation and evaluate the approach for the remediation of PAH contaminated sediment. A preliminary study of electrode enhanced biodegradation of PAH in sediment slurries showed that naphthalene and phenanthrene concentration decreased significantly within 4 days, and PAH degrading genes increased by almost 2 orders of magnitude. In a sediment microcosm more representative of expected field conditions, graphite cloth was used to form an anode at the sediment-cap interface and a similar cathode was placed a few centimeters above within a thin sand layer. With the application of 2V voltage, ORP increased and pH dropped around the anode reflecting water electrolysis. Various cap amendments (buffers) were employed to moderate pH changes. Bicarbonate was found to be the most effective in laboratory experiments but a slower dissolving buffer, e.g. siderite, may be more effective under field conditions. Phenanthrene concentration was found to decrease slowly with time in the vicinity of the anode. In the sediment at 0-1 cm below the anode, phenanthrene concentrations decreased to ~70% of initial concentration with no bicarbonate, and to ~50% with bicarbonate over ~70 days, whereas those in the control remained relatively constant. PAH degrading gene increased compared with control, providing microbial evidence of PAH biodegradation. A voltage-current relationship, which incorporated separation distance and the area of the electrodes, was established to predict current. A coupled reactive transport model was developed to simulate pH profiles and model results showed that pH is neutralized at the anode with upflowing groundwater seepage. This study demonstrated that electrode enhanced capping can be used to control redox potential in a sediment cap, provide microbial electron acceptors, and stimulate PAH degradation. / text

A collection of 4,10-chrysene derivatives was prepared via the BHQ (Bull-Hutchings- Quayle) reaction, their electronic and morphological properties analysed and assessed for suitability as organic semiconductor (OSC) materials. Larger polycyclic aromatic hydrocarbons (PAHs) such as benzo[k]tetraphenes and dinaphtho[1,2,-b:1',2'- k]chrysenes were then prepared and similarly characterised. An acene-based OSC material TMTES-pentacene was also prepared. It is proposed that non-linear PAH- based OSC materials may provide an alternative to popular acene-based materials; offering advantages in stability, diversity and handling.

Les hydrocarbures aromatiques polycycliques (HAP) sont des polluants organiques persistants (POP) émis par les activités humaines suite à la combustion incomplète de la matière organique (industrie, chauffage, trafic routier...). En raison de leur faible taux de dégradation, de leur toxicité, de leur capacité à être transportés sur de longues distances et de leur bioaccumulation dans la matière organique, les HAP font l'objet d'une surveillance atmosphérique (directive cadre européenne 96/62/CE du 27 septembre 1996). Les bryophytes, plus communément appelées mousses, sont utilisées depuis une trentaine d'années pour la biosurveillance de la qualité de l'air. Leurs caractéristiques biologiques font de ces plantes terrestres d'excellents bioaccumulateurs des dépôts de polluants atmosphériques. Cependant, elles ont été peu utilisées pour la biosurveillance des HAP et pour des échelles spatiales et temporelles très limitées. Dans ce contexte, la thèse a pour objectif de valider l'utilisation de bryophytes comme outils pour la biosurveillance des retombées atmosphériques de HAP à différentes échelles spatio-temporelles. La première phase de ce travail a consisté en un développement analytique afin de valider l'analyse des HAP par chromatographie liquide associée à une détection par fluorescence (CLHP-FLD), l'extraction liquide-liquide des HAP contenus dans les dépôts totaux et l'extraction par liquide pressurisé (PLE) des HAP contenus dans les mousses. Cette dernière a été optimisée, grâce à la réalisation d'un plan d'expériences, et a été complétée par des tests de purification par extraction sur phase solide (SPE). Des études de terrain ont ensuite été réalisées afin d'évaluer les tendances temporelles à l'échelle saisonnière, annuelle et historique, ainsi que les tendances spatiales à l'échelle locale et régionale, des teneurs en HAP dans les mousses. Une étude menée sur des mousses d'herbier prélevées dans le Parc Naturel de Bertiz (Navarre, Espagne) entre 1879 et 2007 a permis d'identifier les sources historiques d'émission des HAP. Les bryophytes apparaissent comme de bons « témoins » de la contamination atmosphérique du passé. Une étude annuelle (2010-2011) de biosurveillance active menée à Bertiz a permis ensuite d'observer des tendances saisonnières des teneurs en HAP dans les mousses Hylocomium splendens (Hedw.) Schimp., liées aux variations des émissions atmosphériques et des conditions météorologiques, en particulier des précipitations. De plus, l'étude annuelle a révélé un fractionnement lors de l'accumulation par les mousses des HAP contenus dans les dépôts totaux, qui résulte d'une affinité des HAP pour les dépôts liée à leur solubilité et d'une affinité des HAP pour le végétal liée à leur propriété lipophile (KOW). Ainsi, le suivi des flux atmosphériques de HAP dans les dépôts totaux ne permet pas de prévoir a priori les teneurs de HAP dans les écosystèmes. Enfin, une analyse multivariée de la distribution spatiale des teneurs en HAP dans l'espèce Hypnum cupressiforme Hedw. prélevée en Espagne (Navarre), France (Île-de-France) et Suisse (Plateau Suisse et région de Bâle) a permis de caractériser les sources de contamination atmosphériques des régions étudiées et l'influence de paramètres environnementaux tels que l'altitude et la pluviométrie. / Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants (POPs) emitted by human activities during incomplete combustion of organic matter (industry, domestic heating, road traffic…). Due to their low degradation rates, toxicity, long-range transport and bioaccumulation in organic matter, PAHs are monitored in the atmosphere (Council Directive 96/62/EC of 27 September 1996). Bryophytes, more commonly called mosses, have been used during the past three decades for biomonitoring air quality. Because of their biological characteristics, these terrestrial plants are excellent bioaccumulators of airborne pollutants. However, few studies concern PAH biomonitoring and they are usually restricted to studies limited in time and space. In this context, the thesis aims to validate bryophytes as tools for biomonitoring atmospheric deposition of PAHs on various space-time scales. The first step of this work consisted in developing the analytical procedures in order to validate PAH analysis by liquid chromatography associated with fluorescence detection (HPLC-FLD), liquid-liquid extraction of PAHs from bulk deposition and pressurized liquid extraction (PLE) of PAHs from mosses. The latter was optimized with a factorial design and was completed by purification tests with solid phase extraction (SPE). Field studies were then carried out to evaluate temporal trends of PAH levels in mosses at seasonal, annual and historical scales, as well as spatial trends, at local and regional scales. A study undertaken on herbarium mosses sampled in Bertiz Natural Park (Navarra, Spain) between 1879 and 2007 leaded to the identification of PAH historical emission sources. Bryophytes appear as excellent “witnesses” of the past atmospheric contamination. An annual biomonitoring study (2010-2011) at Bertiz showed seasonal trends of PAH content in mosses Hylocomium splendens (Hedw.) Schimp., which are related to variations of PAH emissions and weather conditions, particularly precipitations. Moreover, the annual study revealed a fractionation of PAHs while they are transferred from total deposition to the mosses, as the affinity of PAHs for deposition samples was related with their solubility and their affinity for the plant was related to their lipophilic property (KOW). Thus, monitoring PAH fluxes in total deposition does not give an a priori estimation of PAH contents in the ecosystems. Finally, multivariate analysis of the spatial distribution of PAHs in the species Hypnum cupressiforme Hedw. sampled in Spain (Navarra), France (Île-de-France) and Switzerland (Swiss Plateau and Basel area) leaded to the characterization of the atmospheric contamination sources in the different areas and the influence of environmental parameters such as elevation and pluviometry.

No description available.

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

No description available.