A novel route for the synthesis of the polycyclic aromatic hydrocarbon peropyrene (Pp) is reported along with the efforts to synthesize derivatives of Pp, 2,2′- and 5,5′-linked tetracene dimers as candidates for study as singlet fission materials in photovoltaic devices. Peropyrene was synthesized by the McMurry coupling conditions from phenalenone and low-valent titanium species. The crystal structure of Pp is formed by π-stacked molecular pairs in a herringbone arrangement. The direct functionalization of Pp was studied, and several indirect methods for the functionalization of Pp via phenalenone derivatives are reported. Nucleophilicly dependent, regioselective Michael addition pathways for phenalenone are described. Phenalenone forms a nucleophilic complex with bispinacolatodiboron and yields chiral 3,3′-linked phenalenone dimers and a bicyclo[3.2.1]octane derivative product of an unusual 3,4 addition. An active complex product of phenalenone and (dimethylphenylsilyl)boronic acid pinacolic ester forms Pp directly. The synthesis of 2,2′- and 5,5′-linked tetracene dimers led to the study of the reduction of 1-arylprop-2-yn-1-ol derivatives via TFA-catalyzed hydride transfer from triethylsilane. Substrates with terminal and TMS-protected alkynes showed silane exchange upon reduction. A TMS-protected, terminal alkyne became triethylsilyl-protected by about 50% whereas only triethylsilyl-protected, terminal alkyne was observed from the reduction of an unprotected, terminal alkyne. A new conformational polymorph of 1,4-bis(triisopropylsilyl)buta-1,3-diyne is reported. Five other rotamers are studied by density functional theory as possible candidates of conformational polymorphism by the analysis of torsional strain energies. The relative stabilities and interconversion equilibria of the seven conformational isomers are studied.

Nonbenzenoid carbocyclic rings are postulated to serve as important structural elements toward tuning the chemical and electronic properties of extended polycyclic aromatic hydrocarbons (PAHs, or namely nanographenes), necessitating a rational and atomically precise synthetic approach toward their fabrication. Here, using a combined bottom-up in-solution and on-surface synthetic approach, we report the synthesis of nonbenzenoid open-shell nanographenes containing two pairs of embedded pentagonal and heptagonal rings. Extensive characterization of the resultant nanographene in solution shows a low optical gap, and an open-shell singlet ground state with a low singlet–triplet gap. Employing ultra-high-resolution scanning tunneling microscopy and spectroscopy, we conduct atomic-scale structural and electronic studies on a cyclopenta-fused derivative on a Au(111) surface. The resultant five to seven rings embedded nanographene displays an extremely narrow energy gap of 0.27 eV and exhibits a pronounced open-shell biradical character close to 1 (y0 = 0.92). Our experimental results are supported by mean-field and multiconfigurational quantum chemical calculations. Access to large nanographenes with a combination of nonbenzenoid topologies and open-shell character should have wide implications in harnessing new functionalities toward the realization of future organic electronic and spintronic devices.

This dissertation summarizes my research in the Nuckolls group on two projects, with a central theme of achieving control of electronic coupling in various nanoscale systems. The two studies of interest aim at the study of emerging properties from alkali-doping of polyaromatic hydrocarbons (PAH), and the synthesis of novel metal chalcogen molecular clusters. Chapter 1 is divided into two parts. Part one provides a brief history of the forces we associate with bond formation. We will learn that although defining a “chemical bond” is helpful, it is limited to our incomplete understanding of what forces contribute to its existence. The behavior of an electron in externally applied magnetic fields will be discussed, where the collective behavior of electrons in a material can be measured, showing a myriad of emerging properties. The known superconducting alkali-doped PAHs are introduced, followed by the unresolved problems of reproducibility and lack of structural data to accompany superconducting samples. Finally, the proximity of AFM to superconductivity is discussed, which could give us insights on further exploration of hight temperature organic superconductors. Part two introduces atomically precise clusters of atoms, also knows as superatoms. Various synthetic approaches to create metal chalcogenide superatoms are introduced. Next, a closer look into the cobalt selenide core, [Co6Se8], is presented. The ability to selectively substitute the ligands on this superatom, achieves dimensional control. The subunit can be seen as a 0-dimensional subunit, where it readily gives away its electrons. Furthermore, assembly of the clusters into 1-, 2-, and 3-dimensional structures is described. Chapter 2 introduces a novel approach to acquire phase pure alkali-doped PAHs, p-terphenyl specifically. Previous reports of solution-processed doping of PAH have inspired highly reliable synthesis of these salts, by employing a chelating agent to stabilize the alkali metal. The first half of chapter 2 analyzes one such crystal in detail, describing emerging AFM fluctuations. The AFM coupling between nearest neighboring p-terphenyls occurs in all three crystallographic directions. Interestingly, this coupling can be seen as an unconventional bond between two terphenyl units along the hard axis, and resembles resonance structures seen in polyacetylene. The second half of the chapter further investigates the novel method, obtaining a library of alkali-doped p-terphenyls. This approach allows for selective variation of either the alkali-metal, the chelating agent, or the electronic structure of p-terphenyl. Obtaining nearly a dozen structures allows for a study of trends of doping level and accompanied magnetic properties. Lastly, Chapter 3 proves a new mechanism for ligand substitution of cobalt selenide superatomic clusters, using an easily removable carbene as the ligand. This approach grants access to new surface ligands and core shapes to expand the properties of these superatoms. Through this approach, larger atomically precise materials can be targeted, giving rise to new types of electronic properties.

In this work a new simplified procedure for isolation and determination of PAH in smoked meat products was developed. This procedure is using ASE as selective extraction technique. Its principle is addition of silicagel activated during 18 hours at 140 °C directly to the extraction cell in ratio 10 g to 1 g of homogenized sample. In the next step the sample is extracted by n-hexane at 100 °C and 10 MPa for three 10 minutes static extraction cycles. The flush volume is 60 % and the purge time 120 sec. During the extraction silicagel adsorb koextracted lipids and thus the obtained extract is suitable for immediate HPLC-FLD analysis. On the contrary, the classical extraction procedures with nonpolar solvent require difficult purification of extract for removal of unwanted lipids. Mostly applied techniques here are GPC and SPE. The new procedure was validated for determination of B[a]P as well as for determination of 4 PAH (B[a]A, CHR, B[b]F, B[a]P) in smoked sausages. It meets all requirements to be set by Regulation (EC) No 333/2007, respective by new Regulation (EC) No 836/2011. After the method validation, the content of 4 PAH was investigated in twelve samples of various smoked sausages manufactured in Slovakia. Two analyzed products showed high PAH levels exceeding maximum legislation limits set for B[a]P as well as for sum of 4 PAH by Regulation (EC) No 835/2011.

<p>U okviru ovog istraživanja ispitani su: 1. Optimalni uslovi&nbsp; za<br />eksperimente biodegradacije policikličnih aromatičnih ugljovodonika sa istim i<br />različitim brojem prstenova; 2. Uticaj struture&nbsp; i matriksa na biodegradaciju<br />policikličnih aromatičnih ugljovodonika sa istim brojem prstenova; 3.<br />Fitotoksičnost biljaka&nbsp; (testovi klijavosti i usvajanje policikličnih aromatičnih<br />ugljovodonika); 4. Procena&nbsp; potencijalne&nbsp; biodostupne frakcije primenom<br />različitih hemijskih sorbenata (HPCD, &beta;CD&nbsp; i&nbsp; MCD, XAD4 i TenaxTA)&nbsp; i 5.<br />Korelacija dobijenih rezultata&nbsp; testovima biodegradacije, testovima klijavosti,<br />testovima fitotoksičnosti i rezultata dobijenih iz eksperimenta procene<br />biodostupnosti hemijskim testovima.&nbsp; Rezultati su pokazali da se&nbsp; optimalni<br />uslovi za biodegradaciju&nbsp; postižu dodatkom mineralnih medijuma, inokuluma i<br />surfaktanata.&nbsp; Posmatrajući uticaj sadržaja gline i organske materije i strukture<br />molekula,&nbsp; najveći stepen biorazgradnje ima fluoranten, &scaron;to je u skladu sa<br />njegovim fizičko-hemijskim osobinama, dok se sadržaj pirena i krizena nije<br />mogao jasno korelirati sa sadržajem organske materije i gline.&nbsp; &Scaron;to se tiče<br />testova fitotoksičnosti,&nbsp; sva semena su proklijala, &scaron;to govori u prilog tome&nbsp; da<br />me&scaron;avina ovih kontaminanata&nbsp; pri ispitivanim koncentracijama&nbsp; nije inhibirala<br />klijanje biljaka.&nbsp; Testovi usvojivosti ispitivanih PAH-ova su pokazali da je<br />najmanji procenat usvojivosti semenom dobijen za benzo(a)piren, &scaron;to se može<br />objasniti njegovom kompleksnijom strukturom. Hemijskim testovima za<br />procenu biodostupnosti je sa druge strane pokazano da se desorpcija u prisustvu<br />MCD, XAD4 smole i Tenaxa može koristiti kao jednostavna metoda za procenu<br />potencijalne biodostupne&nbsp; frakcije organskih jedinjenja u sistemima sediment&nbsp; -voda.</p> / <p>The aim of this study was to investigate: 1. The optimal conditions for&nbsp;the biodegradation of polycyclic aromatic hydrocarbons with the same and&nbsp;different numbers of rings; 2. The impact of structure and matrix&nbsp;biodegradation of polycyclic aromatic hydrocarbons with the same number of&nbsp;rings; 3. Phytotoxicity (germination tests and polycyclic aromatic hydrocarbon&nbsp;uptake); 4. The means for assessing the bioavailable fractions using various&nbsp;chemical sorbents (HPCD, &beta;CD, MCD, XAD4 and &nbsp;TenaxTA) and 5. The&nbsp;correlation between the results of the biodegradation tests, germination tests,&nbsp;phytotoxicity tests and the results obtained from the experiments in the&nbsp;assessment of bioavailability and chemical tests. The results showed that the&nbsp;optimal conditions for biodegradation are achieved by the addition of mineral&nbsp;media, inoculum and surfactants. When considering the effect of the contents of&nbsp;clay and organic matter and the structure of the molecules, the highest degree of&nbsp;biodegradation was observed with fluoranthene,&nbsp; which is in line with its&nbsp;physico-chemical properties. The concentrations of pyrene and chrysene were&nbsp;not clearly correlated with the organic matter and clay contents. During thephytotoxicity tests, all seeds sprouted, which speaks in favor of a mixture of&nbsp;these contaminants not inhibiting the germination of the plants. Tests for the&nbsp;uptake of the investigated PAHs showed that the lowest percentage seed uptake&nbsp;was for benzo(a)pyrene, which is explained by its more complex structure.&nbsp;Chemical tests for evaluating bioavailability have shown that desorption in the&nbsp;presence of MCD, XAD4 and Tenax resins can be used as a simple method for&nbsp;the evaluation of a potential bioavailable fraction of organic compounds in&nbsp;water-sediment systems.</p>

<p>Zadatak ove doktorske disertacije je bio da se utvrdi uticaj različitih tehnolo&scaron;kih parametara na formiranje boje Petrovačke kobasice, kao i da se modelovanjem tradicionalne tehnologije utvrdi zavisnost između brojnih tehnolo&scaron;kih parametara i optimalnog kvaliteta boje ovog tradicionalnog proizvoda, radi standardizacije kvaliteta i bezbednosti, a u cilju dobijanja prepoznatljivog proizvoda vrhunskog kvaliteta koji bi se kontinuirano proizvodio.<br />U cilju realizacije postavljenih zadataka tokom tri proizvodne sezone je izrađeno 13 modela Petrovačke kobasice kako bi se ispitao uticaj sledećih varijabilnih tehnolo&scaron;kih parametara: proizvodne sezone, vremena otko&scaron;tavanja mesa post mortem, vrste upotrebljenog omotača (prirodni i ve&scaron;tački), ručnog i ma&scaron;inskog me&scaron;anja, dimljenja u tradicionalnim i kontrolisanim uslovima, su&scaron;enja i zrenja u tradicionalnim i kontrolisanim uslovima, dodatka izolovane autohtone starter kulture, vremena skladi&scaron;tenja i načina pakovanja (neupakovane, pakovane u vakuumu i modifikovanoj atmosferi) na proces formiranja boje.<br />Formiranje boje Petrovačke kobasice tokom procesa dimljenja, su&scaron;enja i skladi&scaron;tenja praćeno je određivanjem instrumentalnih pokazatelja boje (L*, a*, b*, h, C*, R, BI i &Delta;E) na povr&scaron;ini i preseku Petrovačkih kobasica. Utvrđeni su brojni tehnolo&scaron;ki parametri (vrednost pH, sadržaj vlage, sadržaj ukupnih masti, sadržaj ukupnog pepela i sadržaj hlorida), pokazatelji senzornog kvaliteta (spolja&scaron;nji izgled i stanje omotača, boja i održivost boje na preseku, ukupan senzorni kvalitet) i kvalitet ljute začinske paprike.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Analizom rezultata dobijenih u ovim ispitivanjima zaključeno je da su kobasice izrađene od ohlađenog mesa dimljene i su&scaron;ene u tradicionalnim uslovima (B1 i B2 grupe) imale optimalan kvalitet boje i bile vrhunskog (za&scaron;tićenog) senzornog kvaliteta. Niže temperature (8,30&deg;C-10,7&deg;C) tokom procesa dimljenja i su&scaron;enja, sporiji pad vrednosti pH, od 5,69 (nadev) do ~5,4 (na kraju procesa fermentacije) i sadržaj hlorida ~ 3% u gotovom proizvodu, uz dodatak kvalitetne ljute začinske paprike omogućili su formiranje optimalne boje ove grupe kobasica. Optimalnu boju preseka kobasica karakteri&scaron;u numerički manje vrednosti instrumentalnih pokazatelja boje (L*, a*, b*, h, C* i BI) u odnosu na kobasice sa nižim senzornim ocenama za boju. Tokom skladi&scaron;tenja (od kraja su&scaron;enja do 270. dana proizvodnje) utvrđene su manje promene instrumentalnih pokazatelja boje na povr&scaron;ini i preseku Petrovačkih kobasica kada su skladi&scaron;tene upakovane (vakuum i modifikovana atmosfera) u poređenju sa neupakovanim. Pakovanje u vakuumu i modifikovanoj atmosferi je dobro re&scaron;enje za očuvanje optimalnih karakteristika boje kobasica, jer su upakovane kobasice B1 i B2 grupe skladi&scaron;tene 4 meseca od zavr&scaron;etka procesa su&scaron;enja (od 90. do 210. dana od dana proizvodnje) bez promena senzornog kvaliteta boje, a zatim su do kraja perioda skladi&scaron;tenja (270. dana proizvodnje) promene bile neznatne.<br />Uzimajuću u obzir da su ova istraživanja deo &scaron;ire koncipitranih istraživanja razvoja tradicionalne tehnologije proizvodnje Petrovačke kobasice i standardizacije kvaliteta i bezbednosti, ispitan je uticaj varijabilnih tehnolo&scaron;kih parametara i na formiranje policikličnih aromatičnih ugljovodonika u Petrovačkoj kobasici, kao veoma važnih pokazatelja zdravstvene bezbednosti kobasica.<br />Jedan od najznačajnijih rezultata u ovim istraživanjima je da benzo[a]piren nije detektovan ni u jednom uzorku Petrovačke kobasice. Takođe je zaključeno da je Petrovačka kobasica dimljena na tradicionalan način, kao i u industrijskim uslovima bezbedna za potro&scaron;ače sa aspekta sadržaja policikličnih aromatičnih ugljovodonika, jer su svi ispitani uzorci kobasica ispunjavali uslove propisane domaćim i evropskim propisima.</p> / <p>The aim of this Ph.D. dissertation was to determine the influence of various technological parameters on the colour formation of Petrovačka kobasica, as well as to define correlation between number of technological parameters and optimal colour quality of traditional product (by modelling traditional technology), in order to standardize quality and safety, and consequently with the main goal to obtain a recognizable high quality product that could be continuously produced throughout the whole year period.<br />To achieve the defined tasks in three production season 13 models of Petrovačka kobasica were produced in order to examine the effect of the following variable technological parameters: production season, post mortem time of meat deboning, type of the casing (natural and artificial), manual or mechanical mixing, smoking in traditional and controlled conditions, drying and ripening in traditional and controlled conditions, the addition of isolated indigenous starter culture, and storage time and packaging (unwrapped, packed in vacuum and modified atmosphere) in the process of colour formation.<br />Colour formation of Petrovačka kobasica during smoking and drying processes and storage was followed by determination of instrumental colour parameters (L*, a*, b*, h, C*, R, BI and &Delta;E) on the surface and cut cross section of Petrovačka kobasica. The number of technological parameters (pH, content of moisture, total fat, total ash and chloride), indicators of sensory quality (sausage appearance and condition of casing, colour and colour stability at the cut cross section, the overall sensory quality) and quality of red hot paprika powder were determined.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Analysing the results obtained in these studies it was concluded that sausages produced from chilled meat and smoked in traditional conditions (sausages of B1 and B2 groups) had the optimal colour quality and superior (protected) sensory quality. Lower temperatures (8.30&deg;C-10.7&deg;C) during smoking and drying processes, slower decrease of pH value from 5.69 (raw sausage after stuffing) to ~ 5.4 (at the end of the fermentation process) and the chloride content ~ 3% in the final product, with the addition of high quality red hot paprika powder enable the formation of the optimal colour of these groups of sausages. Optimal colour of cut cross section of sausages was characterized with numerically smaller values of instrumental colour parameters (L*, a*, b*, h, C* and BI) in relation to sausages with lower scores for sensory evaluated colour. During storage (from the end of drying process up to 270 days of production), minor changes of instrumental colour characteristics on the surface and cut cross section of Petrovačka kobasica were noted when sausages were stored packed in vacuum or modified atmosphere, compared with unpackaged ones. Packing in vacuum and modified atmosphere is a good solution for the preservation of optimal colour characteristics, as packaged sausages of B1 and B2 groups stored for 4 months from the end of the drying process (from 90 to 210 days from the date of production) had no changes in sensory evaluated colour quality. Further, until the end of storage (270 days of production) just minor changes of this sensory parameter were noticed.<br />Considering that these investigations are a part of wider conceived researches of development of traditional technology of Petrovačka kobasica and standardization of quality and safety, the influence of variable technological parameters on the formation of polycyclic aromatic hydrocarbons in Petrovačka kobasica, as a very important indicator of health safety of sausage, were also studied.<br />One of the most important results of these researches is that benzo[a]pyrene was not detected in any sample of Petrovačka kobasica. It was also concluded that Petrovačka kobasica smoked in traditional way, as well as in industrial conditions was safe for consumers in the terms of the content of polycyclic aromatic hydrocarbons, as all samples of analysed sausages meet the requirements defined by national and European regulations.</p>

Polyaromatic hydrocarbons (PAHs) are contaminants synthesized through incomplete combustion of carbon based substances. PAHs are known to be photodynamic and toxicity increases exponentially when in contact with ultraviolet radiation (UV). The effect of UV absent recovery periods and potential for latent toxicity during photo-induced toxicity are previously unknown and are not included within the toxicity model. Results of equal interval tests further support the current reciprocity model as a good indicator of PAH photo-induced toxicity. Interval test results also indicate a possible presence of time-dependent toxicity and recovery thresholds and should be included into toxicity risk assessments. Moreover, results of latent effects assays show that latent mortality is a significant response to PAH photo-induced toxicity and should be included into toxicity risk assessments. The present research demonstrates that UV exposure time rate is a significant driving force of PAH photo-induced toxicity.

The former military air-base Hradcany is among the most contaminated with organic pollutants localities in Czech Republic. Main cleanup strategy in the area is the bioremediation taking advantage on the natural potential of the autochthonous soil microorganisms to evolve catabolic pathways for in situ degradation of the pollutant. The diversity and abundance of the pathways, as well as the specificity and activity of the encoded enzymes are priority biotic factors determining the bioremediation efficiency. Main task of this work was to analyze the bacterial diversity in jet fuel contaminated soils based on key catabolic genes encoding the Rieske non-haem iron dioxygenases of the toluene/ biphenyl oxygenase branch. High molecular soil DNA was extracted and the sequences encoding catabolic genes were selectively enriched by hybridization to biotinylated oligonucleotides on magnetic microbeads with covalently bound streptavidin. Fragments of the genes for the -subunits of Rieske non-haem iron oxygenases were amplified and analyzed by restriction analysis, cloning and sequencing. Their evolutionary histories were inferred using the Neighbour-Joining and the maximum likelihood methods. The catabolic genes diversity in the actively bioremediated and highly polluted soil HRB was compared with the diversity in the...

The effect of ultra-high temperature (UHT) on production of polycyclic aromatic hydrocarbons (PAHs) on the surface of beef steaks was determined. Beef steaks were treated with five treatments, raw, UHT, UHT/grill marks, UHT/grill marks/microwave, and charcoal grilled. Four PAHs, benzo[a]pyrene, benz[a]anthracene, benzo[b]fluoranthene, and benzo[k]fluoranthene, were quantified. High performance liquid chromatography (HPLC) and gas chromatography (GC) were used to purify and analyze the PAH extracts, respectively. Levels of PAH found on charcoal-grilled steaks were higher than those observed in the literature. A balanced incomplete block design was used to analyze the data. There were no significant differences among the treatments in the production of the benzofluoranthenes. There were significant increases in production of benzo[a]pyrene and benz[a]anthracene when grill marks were applied to the UHT steak. Microwaving significantly decreased the levels of benzo[a]pyrene and benz[a]anthracene. The production of these PAHs on UHT/grill mark/microwave steak did not differ significantly from the charcoal-grilled steak in the levels of PAH quantified.

The overall goal of this work was to investigate microbial activity leading to the anaerobic degradation of polycyclic aromatic hydrocarbons and an organophilic clay sediment cap used at a creosote-contaminated Superfund site. To determine whether or not PAHs were being degraded under anaerobic conditions in situ, groundwater and sediment porewater samples were analyzed for metabolic biomarkers, or metabolites, formed in the anaerobic degradation of naphthalene (a low-molecular weight PAH). In addition, a groundwater push-pull method was developed to evaluate whether the transformation of deuterated naphthalene to a deuterated metabolite could be monitored in situ and if conservative rates of transformation can be defined using this method. Metabolites of anaerobic naphthalene degradation were detected in all samples that also contained significant levels of naphthalene. Anaerobic degradation of naphthalene appears to be widespread in the upland contaminated aquifer, as well as within the adjacent river sediments. A zero-order rate of transformation of naphthalene-D₈ to naphthoic acid-D₇was calculated as 31 nM·d-¹. This study is the first reported use of deuterated naphthalene to provide both conclusive evidence of the in situ production of breakdown metabolites and an in situ rate of transformation. Methane ebullition was observed in areas of the sediment cap footprint associated with organophilic clay that was used a reactive capping material to sequester mobile non-aqueous phase liquid (NAPL) at the site. Anaerobic slurry incubations were constructed using sediment core samples to quantify the contribution of the native sediment and the different layers of capping material (sand and organophilic clay) to the overall methane production. Substrate addition experiments using fresh, unused organophilic clay, as well as measured changes in total carbon in organophilic clay over time supported the hypothesis that microbes can use organophilic clay as a carbon source. Quantitative PCR (qPCR) directed at the mcrA gene enumerated methanogens in field samples and incubations of native sediment and capping materials. Denaturing gradient gel electrophoresis (DGGE) was also performed on DNA extracted from these samples to identify some of the predominant microorganisms within the sediment cap footprint. The organophilic clay incubations produced up to 1500 times more methane than the native sediment and sand cap incubations. The organophilic clay field sample contained the greatest number of methanogens and the native sediment contained the least. However, the native sediment incubations had greater numbers of methanogens compared to their respective field sample and comparable numbers to the organophilic clay incubation. An increase in methane production was observed with the addition of fresh, unused organophilic clay to the already active organophilic clay incubations indicating that organophilic clay stimulates methanogenesis. In addition, organophilic clay retrieved from the field lost about 10% of its total carbon over a 300-day incubation period suggesting that some component of organophilic clay may be converted to methane. DGGE results revealed that some of the predominant groups within the native sediment and sediment cap were Bacteriodetes, Firmicutes, Chloroflexi, and Deltaproteobacteria. An organism 98% similar to Syntrophus sp. was identified in the organophilic clay suggesting this organism may be working in concert with methanogens to convert the organic component of organophilic clay ultimately to methane. The capacity of organophilic clay to sequester organic contaminants will likely change over time as the organic component is removed from the clay. This, in turn, affects the use of this material as a long-term remedial strategy in reduced, contaminated environments.