Although environmental monitoring of polycyclic aromatic hydrocarbons (PAH) is an essential step to prevent human exposure to contaminated sites, it provides little information on the actual human uptake and subsequent risks. To this end, urine analysis of short-term biomarkers such as PAH metabolites fill an important niche. The general approach follows the sequence of urine hydrolysis, sample clean-up and pre-concentration, chromatographic separation and determination. Whereas chromatographic methods are based on well established laboratory techniques, the development of easy-to-use, cost-effective and large sample throughput techniques is becoming increasingly relevant to investigate adverse PAH effects on large human populations. This thesis compares the room-temperature, 77K and 4.2K fluorescence properties of 1-naphthol, 2-naphthol, 1-hydroxypyrene, 2-hydroxyfluorene, 3-hydroxybenzopyrene and 9-hydroxyphenanthrene. These metabolites are used as model biomarkers to investigate the analytical potential of a simple method of analysis based on Solid-Phase Extraction and Room-Temperature Fluorimetry. Metabolites are directly determined in the eluting solvent (methanol) without the need of previous separation via multidimensional formats. Metabolite recoveries varied between 87 ± 1.51% (9-hydroxyphenanthrene) and 99 ± 1.05% (3-hydroxybenzopyrene). For 10mL of urine samples, limits of detection varied between 0.01ng.mL-1 (3-hydroxybenzopyrene) and 0.6ng.mL-1 (2-hydroxynaphthalene). These figures of merit demonstrate the potential of this approach for screening purposes

No description available.

<p>Dibenzothiophene (DBT) is a constituent of creosote and petroleum waste contamination, it is a model compound for more complex thiophenes, and its degradation by mixed microbial communities has received little attention. The chemical characteristics, environmental fate and ecotoxicology of DBT degradation products are not well understood. This research investigated DBT degradation in an enrichment culture derived from creosote-contaminated estuarian sediment using a suite of assays to monitor bacterial populations, bacterial growth, degradation products, DBT loss, and toxicity. Ultraviolet (UV) irradiation was evaluated as a sequential treatment following biodegradation. Additionally, to advance SYBR-Green qPCR methodology for characterizing mixed microbial communities, an alternative approach for evaluating qPCR data using a sigmoidal model to fit the amplification curve was compared to the conventional approach in artificial mixed communities. The overall objective of this research was to gain a comprehensive understanding of the degradation of a model heterocyclic PAH, DBT, by a mixed microbial community, particularly within the context of remediation goals.</p><p>DBT biodegradation was evaluated in laboratory scale cultures with and without pH control. The microbial community was monitored with 10 primer sets using SYBR-Green quantitative polymerase chain reaction (qPCR). Twenty-seven degradation products were identified by gas chromatography and mass spectrometry (GC/MS). The diversity of these products indicated that multiple pathways functioned in the community. DBT degradation appeared inhibited under acidic conditions. Toxicity to bioluminescent bacteria <italic>Vibrio fischeri</italic> more than doubled in the first few days of degradation, was never reduced below initial levels, and was attributed in part to one or more degradation products. UV treatment following biodegradation was explored using a monochromatic (254 nm) low-pressure UV lamp. While DBT was not extensively photooxidized, several biodegradation products were susceptible to UV treatment. At higher doses, UV treatment following DBT biodegradation exacerbated cardiac defects in <italic>Fundulus heteroclitus</italic> embryos, but slightly reduced toxicity to <italic>V. fischeri</italic>.</p><p>This research provides a uniquely comprehensive view of the DBT degradation process, identifying bacterial populations previously unassociated with PAH biodegradation, as well as potentially hazardous products that may form during biodegradation. Additionally, this research contributes to development of unconventional remediation strategies combining microbial degradation with subsequent UV treatment.</p> / Dissertation

No description available.

Humans are continuously exposed to mixtures of environmental pollutants. Polycyclic aromatic hydrocarbons (PAHs), such as 2-naphthol, and heavy metals, such as lead, are some of these pollutants. Results from epidemiological studies show associations between exposure to 2-naphthol, exposure to lead, and obesity. However, the individual and combined effects of 2-naphthol and lead on fat cell development (adipogenesis) have not been directly characterized in a biological system. In this study, we evaluated the effects of 2-naphthol and/or lead on adipogenesis using mouse 3T3-L1 cells. Cells were exposed to different doses of 2-naphthol and/or lead. Induced terminal differentiation was evaluated by cell morphology, lipid production, and mRNA expression of marker genes characteristic of either early adipocyte differentiation: CCAAT-enhancer-binding protein β (C/EBPβ), insulin receptor substrate 2 (IRS2), and sterol responsive element binding protein 1 c (SREBP1c); or terminal differentiation: C/EBPα, peroxisome proliferator-activated receptor-γ (PPARγ), and fatty acid binding protein 4 (aP2). Production of antimicrobial peptide cathelicidin (Camp), which is produced by differentiating adipocytes and modulates inflammation and immunity, was also evaluated. Cell morphology changes and increased lipid accumulation indicated that, individually, 2-naphthol and lead induced 3T3-L1 differentiation; however, the highest dose of lead (10 μM) showed the lowest induction level. During terminal differentiation, 2-naphthol and low doses of lead increased C/EBPα, PPARγ, and aP2 expression, whereas 10 μM lead suppressed PPARγ and aP2. During early differentiation, 2-naphthol stimulated C/EBPβ, IRS2, and SREBP1c expression, while lead upregulated C/EBPα and aP2. The 2-naphthol/10 μM lead mixture induced a counterbalancing effect on 3T3-L1 adipogenesis, where 10 μM lead suppressed 2-naphthol-induced adipogenesis. Moreover, 2-naphthol elevated Camp expression in a dose-dependent manner, whereas lead slightly increased Camp at lower doses but suppressed it at 10 μM. The 2-naphthol/10 μM lead mixture showed no effect on Camp expression. In conclusion, 2-naphthol and low lead doses accelerate adipocyte differentiation and Camp production in 3T3-L1 cells; however, high doses of lead attenuate the induction. This effect of lead at high dose counterbalances the upregulation of adipocyte differentiation and Camp production by 2-naphthol. Together, these findings indicate that 2-naphthol and lead play potential roles in the development of inflammation and obesity.

Polycyclic aromatic hydrocarbon (PAH) compounds, which are common to coal tar and coal-tar-based products, are ubiquitous environmental contaminates with carcinogenic effects to human health and aquatic life. Transport of PAHs via solid phase particulate motion, gaseous phase volatilization, and aqueous phase dissolution into urban waterbodies of PAH compounds from coal-tar-based pavement sealant products has been studied. Pavement rejuvenators are products applied to increase the usable life of pavement. Coal-tar-based rejuvenators contain a significantly larger mass fraction of coal-tar with respect to coal-tar-based sealants, but pavement rejuvenators have not been as extensively studied as pavement sealants. Chemical analysis of detached pavement material treated with coal-tar-bases, asphalt-based, and bio-based rejuvenators was conducted with gas chromatography – mass spectrometry (GC/MS) analysis for 16 PAH compounds and two aromatic heterocyclic organic compounds following extraction with methylene chloride. Detached pavement material was collected from 19 simulated asphalt surface abrasion experiments that used a model mobile load simulator (MMLS) test apparatus that replicated surface challenges from vehicular traffic. The MMLS test apparatus configuration allowed asphalt disc samples treated with different rejuvenation products, to be tested and for detached material to be collected and quantified prior to GC/MS analysis. Test cases evaluated the influence of rejuvenation product type and cure time, as well as the effect of sand application (simulating sand application during slippery winter storm conditions) had on detached particulate and ultimate PAH compound loading. The average mass of particulate detachment from samples following a 48 hour cure time, for the asphalt-based and coal-tar-based rejuvenator products were 0.347 g and 0.480 g, respectively. This mass of detached material was lower than that from pavement treated with bio-based rejuvenator and the control (not treated), which had 4.858 g and 2.567 g of detached particulate material, respectively. When the product cure time was increased to three weeks, which was significantly long enough to capture effects of compound volatilization, average particulate detachment increased to 0.882 g for the coal-tar-based rejuvenator and decreased for the bio-based rejuvenator to 2.600 g. Six tests performed with a single application of winter storm sand after a 48 hour product cure time showed an increase in average particulate detachment to 1.450 g and 0.617 g for pavement treated with the asphalt-based and coal-tar-based rejuvenators, respectively. Conversely, under the same conditions, a reduction in average detached particulate to 3.749 g was observed for the bio-based product. Detached particulate material quantities for each test case were used with the respective cumulative concentration of 16 PAH compounds quantified to make an assessment on the potential PAH compound contamination via solid phase particle transport. The average PAH compound concentration in particulate detached from pavement treated with a coal-tar-based rejuvenator was 3062.8 mg PAH per kg of particulate. This was an order of magnitude higher than the average PAH concentration measured in particulate detached from the two control pavement samples and the two asphalt-based samples after a 48 hour cure time, which were 322.1 and 508.1 mg PAH per kg detached particulate, respectively. PAH compound concentrations were also normalized by the surface area of pavement treated with a rejuvenator to determine the potential PAH compound contamination per unit area. Normalized results for each rejuvenator type were averaged to make an overall evaluation of the potential rejuvenator specific PAH compound loading. The coal-tar-based, bio-based, and asphalt-based rejuvenators had a normalized cumulative solid-phase PAH compound release of 2.35, 0.88, and 0.17 mg PAH per square foot of pavement rejuvenated, respectively. In addition, carbazole was quantified in all pavement samples treated with the coal-tar-based rejuvenator at an average concentration of 125.6 mg carbazole per kg detached particulate. Acridine was quantified in detached particulate from five of seven coal-tar-based test performed at an average concentration (excluding non-detection samples) of 42.1 mg acridine per kg detached particulate.

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.

Fireworks on Independence Day have been identified as a nationwide but short-term source of particulate matter in the U.S. No study has specifically examined their impacts on ambient polycyclic aromatic hydrocarbons (PAHs). Based on data between 1990 and 2019 in the Air Quality System, we identified 76 unique events that had PAH measurements on both July 4th days and control days (within 15 days before and after July 4th). We compared concentrations and diagnostic ratios of 16 priority PAHs between event and control days using Wilcoxon signed-rank tests and multivariable regressions. A local PAH monitoring campaign was conducted at eight sites in Memphis, Tennessee, to obtain a close observation of PAH changes. The national geometric mean (GM) concentrations of summed 16 PAHs (ΣPAHs) were similar between event and control days (48.1 ng/m3 vs. 52.8 ng/m3, p = 0.98). About a quarter of events had elevated PAH concentrations compared with control days. Higher diagnostic ratios were found on event days, suggesting more contributions from fireworks sources. PAHs on July 4th were unlikely to cause acute or chronic health effects. While the local monitoring showed a 15% increase of ΣPAHs on July 4th, the difference was not significant (p = 0.62). Elevated PAH concentrations occurred at sites near fireworks sources and without major traffics, but did not occur at those in remote areas or near major interstate highways. In conclusion, this study finds that Independence Day fireworks have negligible impacts on atmospheric PAHs at the national level, and are unlikely to pose significant health risks. The firework effect is localized within a limited geographic scale, suggesting potential needs for local monitoring and control programs.

Polycyclic aromatic hydrocarbons (PAH) are important environmental pollutants generally formed during incomplete combustion of organic matter containing carbon and hydrogen. Introduced into the human body by adsorption through the skin, ingestion or inhalation, the biotransformation processes of PAH lead to the formation of multiple metabolites. Due to the short elimination lifetime from the body, the quantitative determination of monohydroxy-PAH (OH-PAH) in urine samples provides accurate information on recent exposure to environmental PAH. Urine analysis of OH-PAH with established methodology relies on sample clean-up and pre-concentration followed by chromatographic separation and quantification. Although chromatographic techniques provide reliable results in the analysis of OH-PAH, their experimental procedures are time consuming and expensive. Additional problems arise when laboratory procedures are scaled up to handle thousands of samples under mass screening conditions. Under the prospective of a sustainable environment, the large usage of organic solvents is one of the main limitations of current chromatographic methodology. It is within this context that new analytical approaches based on easy-to-use and cost-effective methodology become extremely relevant. This dissertation focuses on the development of screening methodology for the routine analysis of PAH metabolites in numerous samples. It explores the room-temperature fluorescence properties of six metabolites originating from parent PAH included in the Environmental Protection Agency priority pollutants list. 1- hydroxyfluorene, 1-hydroxypyrene, 6-hydroxychrysene, 9-hydroxyphenanthrene, 3- hydroxybenzo[a]pyrene and 4-hydroxybenzo[a]pyrene are used as model biomarkers to investigate the analytical potential of new methods based on solid-phase extraction (SPE) and iii room-temperature fluorescence (RTF) spectroscopy. Quantitative determination of metabolites is carried out either in the eluent extract[1, 2] or on the surface of extraction membranes[3, 4] . The direct determination – i.e., no chromatographic separation - of the six metabolites is based on the collection of excitation-emission matrices and synchronous fluorescence spectra.