Reduced organic sulfur (ROS) compounds are environmentally ubiquitous and play an important role in sulfur cycling as well as in biogeochemical cycles of toxic metals, in particular mercury. Development of effective methods for analysis of ROS in environmental samples and investigations on the interactions of ROS with mercury are critical for understanding the role of ROS in mercury cycling, yet both of which are poorly studied. Covalent affinity chromatography-based methods were attempted for analysis of ROS in environmental water samples. A method was developed for analysis of environmental thiols, by preconcentration using affinity covalent chromatographic column or solid phase extraction, followed by releasing of thiols from the thiopropyl sepharose gel using TCEP and analysis using HPLC-UV or HPLC-FL. Under the optimized conditions, the detection limits of the method using HPLC-FL detection were 0.45 and 0.36 nM for Cys and GSH, respectively. Our results suggest that covalent affinity methods are efficient for thiol enrichment and interference elimination, demonstrating their promising applications in developing a sensitive, reliable, and useful technique for thiol analysis in environmental water samples. The dissolution of mercury sulfide (HgS) in the presence of ROS and dissolved organic matter (DOM) was investigated, by quantifying the effects of ROS on HgS dissolution and determining the speciation of the mercury released from ROS-induced HgS dissolution. It was observed that the presence of small ROS (e.g., Cys and GSH) and large molecule DOM, in particular at high concentrations, could significantly enhance the dissolution of HgS. The dissolved Hg during HgS dissolution determined using the conventional 0.22 µm cutoff method could include colloidal Hg (e.g., HgS colloids) and truly dissolved Hg (e.g., Hg-ROS complexes). A centrifugal filtration method (with 3 kDa MWCO) was employed to characterize the speciation and reactivity of the Hg released during ROS-enhanced HgS dissolution. The presence of small ROS could produce a considerable fraction (about 40% of total mercury in the solution) of truly dissolved mercury (< 3 kDa), probably due to the formation of Hg-Cys or Hg-GSH complexes. The truly dissolved Hg formed during GSH- or Cys-enhanced HgS dissolution was directly reducible (100% for GSH and 40% for Cys) by stannous chloride, demonstrating its potential role in Hg transformation and bioaccumulation.

Dissimilatory metal-reducing bacteria (DMRB) play an important role in the biogeochemical cycling of metals. DMRB are unique in that they possess the ability to couple metal reduction with their metabolism. Microbial Fe(III) respiration is a central component of a variety of environmentally important processes, including the biogeochemical cycling of iron and carbon in redox stratified water and sediments, the bioremediation of radionuclide-contaminated water, the degradation of toxic hazardous pollutants, and the generation of electricity in microbial fuel cells. Despite this environmental and evolutionary importance, the molecular mechanism of microbial Fe(III) respiration is poorly understood. Current models of the molecular mechanism of microbial metal respiration are based on direct enzymatic, Fe(III) solubilization, and electron shuttling pathways. Fe(III) oxides are solid at circumneutral pH and therefore unable to come into direct contact with the microbial inner membrane, these bacteria must utilize an alternative strategy for iron reduction. Reduced organic compounds such as thiols are prominent in natural environments where DMRB are found. These thiol compounds are redox reactive and are capable of abiotically reducing Fe(III) oxides at high rates S. oneidensis wild-type and ΔluxS anaerobic biofilm formation phenotypes were examined under a variety of electron donor-electron acceptor pairs, including lactate or formate as the electron donor and fumarate, thiosulfate, or Fe(III) oxide-coated silica surfaces as the terminal electron acceptor. The rates of biofilm formation under the aforementioned growth conditions as well as in the presence of exogenous thiol compounds indicate that ∆luxS formed biofilms at rates only 5-10% of the wild-type strain and ∆luxS biofilm formation rates were restored to wild-type levels by addition of a variety of exogenous compounds including cysteine, glutathione, homocysteine, methionine, serine, and homoserine. Cell adsorption isotherm analyses results indicate that wild-type is can attach to the surface of hematite particles attachment , but ΔluxS is unable to attach the hematite surfaces. These results indicate that biofilm formation is not required for Fe(III) oxide reduction by S. oneidensis ∆luxS anaerobic biofilm formation rates were restored to wild-type levels by addition of exogenous auntoinducer-2 (AI-2), a by-product of homocysteine production in the Activated Methyl Cycle. This discovery led to subsequent experiments performed to detect the production and utilization of AI-2 by wild-type and ∆luxS strains under aerobic and anaerobic conditions. AI-2 production experiments showed wild-type, but not ΔluxS, was capable of producing AI-2. The addition of exogenous S. oneidensis and Vibrio harveyi-produced AI-2 to wild-type and ∆luxS resulted in the swift depletion of AI-2 from the media. These results provide evidence that S. oneidensis can produce AI-2 and subsequently utilize its’ own AI-2 as well as AI-2 produced by other bacteria as a carbon and electron source in the absence of preferred carbon sources. S. oneidensis produces and secretes a suite of extracellular thiols under anaerobic Fe(III)-reducing and Mn(III) and Mn(IV)-reducing conditions including cysteine, homocysteine, glutathione, and cyteamine. Exogenous thiols produced by S. oneidensis are intermediates of the Activated Methyl Cycle (AMC) and Transulfurylation Pathway (TSP). Reduced and oxidized thiols were detected, indicating that the thiols are in a constant state of flux between the reduced and oxidized forms and that the concentration of reduced thiols to its’ oxidized counterpart is indicative of the state of metal reduction by the microorganisms. Respiratory phenotypes Based on Fe(III) and Mn(IV) respiratory phenotypes observed in the AMC and TSP pathway mutants (∆luxS, ∆metB, ∆metC and ∆metY) we can infer that cysteine, glutathione, and cysteamine contribute to metal reduction by serving as efficient electron shuttling molecules, while homocysteine is critical for maintenance of the AMC, propagation of thiol biosynthesis, and maintenance of cellular metabolism via the AMC intermediate SAM. Furthermore, these findings suggest that all metal-reducing bacteria require thiol formation to reduce solid metal oxides. Direct contact mechanism is not the dominant means through electrons are transferred and metals are reduced, instead electron shuttles are the maid reduction mechanism.

Land application of anaerobically stabilized biosolids is a beneficial method of handling the solid residuals from a wastewater treatment plant. One of the main issues that restrict land application of biosolids is nuisance odors associated with biosolids. Despite its importance, few studies have been done to enhance our knowledge of odor causing processes. This study was conducted to evaluate the effects of some factors that have been thought to be linked to odor generation from biosolids. The first part of this study has looked at the role of metals, iron and aluminum in particular, in determining the odor causing processes. The results showed that iron correlated well with headspace organic sulfur odor. In general, as the iron content of sludge increased greater amounts of odorous sulfur gases were produced from dewatered biosolids cakes. Aluminum did not show any relationship with organic sulfur odors. Parameters commonly used for assessing the performance of anaerobic digesters (volatile solids reduction (VSR), residual biological activity (RBA) and effluent volatile fatty acid (VFA) content) also showed no correlation with odors. The second part of the study focused on determining the impact of anaerobic digester solids retention time (SRT) on the odor generation from dewatered biosolids cakes and also on elucidating the nature and impact of the various Extracellular Polymeric Substances (EPS) fractions on odors. The results showed that odors decreased with an increase in the anaerobic digester SRT. VSR and RBA correlated with odors; however, as only one type of sludge was assessed, the conclusions about any relationship may not be universal. The results also showed that sulfur gas generation was a function of EPS material bound to iron, again showing that iron plays an important role in odor generation from dewatered sludge cakes. The third part of the study looked at the effects of advanced digestion processes on odor generation. Digested sludge from acid/gas and temperature phased anaerobic digestion systems were analyzed in the lab. The results show that both acid/gas system and temperature phased digestion had a positive impact on odor generation from dewatered biosolids cake. Comparison of sludge from pancake shaped and egg shaped digesters showed that egg shaped digester was more efficient with regard to odor reduction. / Master of Science

<p></p><p><a>COS and CS₂ are sulfur compounds that are formed in natural waters. These compounds are also volatile, which leads them move into the atmosphere and serve as critical precursors to sulfate aerosols. Sulfate aerosols are known to counteract global warming by reflecting solar radiation. One major source of COS and CS₂ stems from the ocean. While previous studies have linked COS and CS₂ formation in these waters to the indirect photolysis of organic sulfur compounds, much of the chemistry behind how this occurs remains unclear. This study examined this chemistry by evaluating how different organic sulfur precursors, water quality constituents, and temperature affected COS and CS₂ formation in natural waters.</a></p> <p>In the first part of this thesis (chapters 2 and 3), nine natural waters ranging in salinity were spiked with various organic sulfur precursors (e.g. cysteine, cystine, dimethylsulfide (DMS) and methionine) exposed to simulated sunlight over varying exposures. Other water quality conditions including the presence of O₂, CO and temperature were also varied. Results indicated that COS and CS₂ formation increased up to 11× and 4×, respectively, after 12 h of sunlight while diurnal cycling exhibited varied effects. COS and CS₂ formation were also strongly affected by the DOC concentration, organic sulfur precursor type, O₂ concentration, and temperature while salinity differences and CO addition did not play a significant role.</p> <p>To then specifically evaluate the role of DOM in cleaner matrices, COS and CS₂ formation was examined in synthetic waters (see chapters 4 and 5). In this case, synthetic waters were spiked with different types of DOM isolates ranging from freshwater to ocean water along with either cysteine or DMS and exposed to simulated sunlight for up to 4 h. Surprisingly, CS₂ was not formed under any of the tested conditions, indicating that other water quality constituents, aside from DOM, were responsible for its formation. However, COS formation was observed. Interestingly, COS formation with cysteine was fairly similar for all DOM types, but increasing DOM concentration actually decreased formation. This is likely due to the dual role of DOM on simultaneously forming and quenching the reactive intermediates (RIs). Additional experiments with quenching agents to RIs (e.g. ³DOM* and ·OH) further indicated that ·OH was not involved in COS formation with cysteine but ³DOM* was involved. This result differed with DMS in that ·OH and ³DOM* were both found to be involved. In addition, treating DOM isolates with sodium borohydride (NaBH₄) to reduce ketone/aldehydes to their corresponding alcohols increased COS formation, which implied that the RIs formed by these functional groups in DOM were not involved. The alcohols formed by this process were not likely to act as quenching agents since they have been shown to low in reactivity. Since ketones are known to form high-energy-triplet-states of DOM while quinones are known to form low-energy-triplet-states of DOM, removing ketones from the system further supported the role of low-energy-triplet-states on COS formation. This was initially hypothesized by findings from the testes on DOM types. In the end there are several major research contributions from this thesis. First, cysteine and DMS have different mechanisms for forming COS. Second, adding O₂ decreased COS formation, but it did not stop it completely, which suggests that further research is required to evaluate the role of RI in the presence of O₂. Lastly, considering the low formation yields of COS and CS₂ formation from the organic sulfur precursors tested in this study, it is believed that some other organic sulfur precursors are missing which are likely to generate these compounds to higher levels and this needs to be investigated in future research. </p><br><p></p>

Dimethyl Sulfide (CH3SCH3, DMS) is the most important natural sulfur compound emitted from the ocean and its oxidation in the atmosphere has been proposed to play an important role in climate modification because some products from DMS oxidation become non-volatile and could participate in particle formation and growth processes. Although it has been demonstrated that aqueous phase reactions are potentially important for understanding DMS oxidation, the kinetics database for aqueous phase transformations is rather limited. In this work, a laser flash photolysis (LFP) ??ng path UV-visible absorption (LPA) technique was employed to investigate the kinetics of the aqueous phase reactions of four organic sulfur compounds produced from DMS oxidation, i.e., dimethylsulfoxide (DMSO), dimethyl-sulfone (DMSO2), methanesulfinate (MSI) and methanesulfonate (MS), with four important aqueous phase radicals, OH, SO4 and #8722;, Cl and Cl2 and #8722;. The temperature-dependent kinetics of the OH and SO4 and #8722; reactions with DMSO, DMSO2 and MS were studied for the first time. OH is found to be the most reactive, while Cl2 and #8722; is the least reactive toward all the sulfur species studied. The less oxidized DMSO and MSI are found to be more reactive than the more oxidized DMSO2 and MS for each radical. The kinetic data have been employed in a Trajectory Ensemble Model to simulate DMS oxidation in the marine atmosphere as a means of assessing the contribution of aqueous phase reactions to the growth of particulate matter. For the first time, oxidation of organic sulfur compounds by SO4 and #8722;, Cl and Cl2 and #8722; are included in the model to simulate DMS chemistry. Our simulations suggest that aqueous phase reactions contribute >97% of MS and ~90% of NSS (Non-Seasalt Sulfate) production, and aqueous phase reactions of the organic sulfur compounds contribute 30% of total particle mass growth. When our kinetic data for the MS + OH reaction were used in the model, it was found that MS + OH could consume ~20% of MS and produce ~8% of NSS, within 3 days under typical marine atmospheric conditions.

Die Aufgabenstellung der vorliegenden Arbeit ergab sich aus der Notwendigkeit organische Schwefelverbindungen in stark belasteten wäßrigen Proben zu identifizieren, um das toxische Potential dieser Wässer abschätzen zu können. Bei der chromatographischen Trennung und Identifizierung der einzelnen Komponenten traten insbesondere dann Probleme auf, wenn die einzelnen Komponenten in Konzentrationsbereichen auftraten die um Größenordnungen differierten. Da auch durch selektive Detektion unbekannte Komponenten nicht direkt identifiziert werden können, wurde angestrebt durch geeignete Probenvorbereitungsschritte einerseits die gesuchten Zielsubstanzen anzureichern und andererseits störende Matrixbestandteile abzutrennen. Ziel der vorliegenden Arbeit war es effektive und möglichst selektive Verfahren zu entwickeln, um organische Schwefelverbindungen aus wäßrigen Proben anzureichern. Im Rahmen dieser Arbeit wurden zwei Möglichkeiten erarbeitet. Für die Anreicherung von leicht- bis mittelflüchtigen Substanzen erwies sich die Adsorption an Ag2S aus der Gasphase als geeignet. Zur Extraktion mittel- bis schwerflüchtiger Verbindungen wurde eine Festphasenextraktionstechnik an einem mit Blei(II)ionen modifizierten Kationenaustauschermaterial entwickelt. Ein Vergleich beider Techniken erfolgte mit dem Verfahren der Festphasenmikroextraktion (SPME). Die adsorptive Anreicherung an Ag2S wurde mit einem Membranextraktionsschritt (ME) , Thermodesorption (TD) und GC/MS gekoppelt. Wie die SPME kann sie für den Nachweis leicht- bis mittelflüchtiger Verbindungen aus flüssigen, festen und gasförmigen Proben eingesetzt werden. Gegenüber der Festphasenmikroextraktion ermöglicht sie den Einsatz größerer Probemengen, was in niedrigeren Nachweisgrenzen (oberer bis mittlerer ng/l-Bereich) resultiert. Nachteile der entwickelten Technik bilden der höhere experimentelle Aufwand und die längeren Analysenzeiten. Das Festphasenextraktionsverfahren an dem mit Pb(II)ionen beladenen Kationenaustauschermaterial erlaubt gegenüber der SPME ebenfalls die Anwendung größerer Probenmengen und höherer Konzentrationen. Beide Verfahren zeigen vergleichbare Nachweisgrenzen (unterer µg/l - bis oberer ng/l-Bereich) für die verwendeten Modellsubstanzen. Sowohl durch die adsorptive Anreicherung an Silbersulfid als auch durch die Festphasenextraktion an Pb(II)-modifizierten Ionenaustauschmaterialien wird die Identifizierung unbekannter organischer Schwefelverbindungen in stark belasteten Proben erheblich erleichtert. Beide Methoden bilden als einfache und leistungsfähige Techniken wirkungsvolle Ergänzungen zu bereits etablierten Anreicherungsverfahren. Neben der Identifizierung und Analyse können die Techniken ebenfalls zur Entfernung von schwefelhaltigen Substanzen aus verschiedenen Matrizes dienen. Anwendungsmöglichkeiten der entwickelten Methoden bestehen neben der Umweltanalytik auch in der Lebensmittelchemie.

Le soufre est présent dans les systèmes pétroliers à la fois sous forme organique et minérale. Il est impliqué dans de nombreuses réactions d'oxydoréduction qui affectent la qualité des huiles (par des réactions de sulfuration ou de désulfuration) et du gaz naturel (par la génération de H2S en contexte de réduction thermochimique des sulfates), ainsi que la porosité des roches réservoirs (par la dissolution de l'anhydrite ou la précipitation de soufre élémentaire ou de pyrobitume). Ces réactions sont gouvernées par la température (et dans une moindre mesure la pression), les conditions d'oxydoréduction et la composition chimique globale du système. La thèse comporte trois parties : (1) une étude thermodynamique des réactions chimiques impliquant le soufre dans les bassins sédimentaires ; (2) une étude expérimentale des réactions de sulfuration et de désulfuration des composés organiques ainsi que de la réduction thermochimique des sulfates; (3) une étude pétrographique et d'inclusions fluides sur des échantillons d'un réservoir carbonaté du bassin Pré-Caspien / Sulfur occurs in petroleum systems as both organic compounds and minerals as well as under different oxidation states. It is involved in a number of redox reactions which may impact the quality of crude oils (through sulfurization or desulfurization reactions) and natural gas (through the generation of H2S during thermochemical sulfate reduction), as well as the petrophysical properties of reservoir rocks (through the dissolution of anhydrite and the precipitation of elemental sulfur and pyrobitumen). These reactions are controlled by temperature (and to a lesser extent pressure), the redox conditions, and the overall chemical composition of the system representing the petroleum reservoir. The thesis consists of three parts: (1) a thermodynamic study of chemical reactions involving sulfur which occur in sedimentary basins; (2) an experimental simulation of sulfurization and desulfurization reactions of organic compounds, as well as of thermochemical sulfate reduction; and (3) a petrographic and fluid inclusion study of carbonate rock samples from a sulfur-rich hydrocarbon reservoir of the northern Caspian Sea

Die Aufgabenstellung der vorliegenden Arbeit ergab sich aus der Notwendigkeit organische Schwefelverbindungen in stark belasteten wäßrigen Proben zu identifizieren, um das toxische Potential dieser Wässer abschätzen zu können. Bei der chromatographischen Trennung und Identifizierung der einzelnen Komponenten traten insbesondere dann Probleme auf, wenn die einzelnen Komponenten in Konzentrationsbereichen auftraten die um Größenordnungen differierten. Da auch durch selektive Detektion unbekannte Komponenten nicht direkt identifiziert werden können, wurde angestrebt durch geeignete Probenvorbereitungsschritte einerseits die gesuchten Zielsubstanzen anzureichern und andererseits störende Matrixbestandteile abzutrennen. Ziel der vorliegenden Arbeit war es effektive und möglichst selektive Verfahren zu entwickeln, um organische Schwefelverbindungen aus wäßrigen Proben anzureichern. Im Rahmen dieser Arbeit wurden zwei Möglichkeiten erarbeitet. Für die Anreicherung von leicht- bis mittelflüchtigen Substanzen erwies sich die Adsorption an Ag2S aus der Gasphase als geeignet. Zur Extraktion mittel- bis schwerflüchtiger Verbindungen wurde eine Festphasenextraktionstechnik an einem mit Blei(II)ionen modifizierten Kationenaustauschermaterial entwickelt. Ein Vergleich beider Techniken erfolgte mit dem Verfahren der Festphasenmikroextraktion (SPME). Die adsorptive Anreicherung an Ag2S wurde mit einem Membranextraktionsschritt (ME) , Thermodesorption (TD) und GC/MS gekoppelt. Wie die SPME kann sie für den Nachweis leicht- bis mittelflüchtiger Verbindungen aus flüssigen, festen und gasförmigen Proben eingesetzt werden. Gegenüber der Festphasenmikroextraktion ermöglicht sie den Einsatz größerer Probemengen, was in niedrigeren Nachweisgrenzen (oberer bis mittlerer ng/l-Bereich) resultiert. Nachteile der entwickelten Technik bilden der höhere experimentelle Aufwand und die längeren Analysenzeiten. Das Festphasenextraktionsverfahren an dem mit Pb(II)ionen beladenen Kationenaustauschermaterial erlaubt gegenüber der SPME ebenfalls die Anwendung größerer Probenmengen und höherer Konzentrationen. Beide Verfahren zeigen vergleichbare Nachweisgrenzen (unterer µg/l - bis oberer ng/l-Bereich) für die verwendeten Modellsubstanzen. Sowohl durch die adsorptive Anreicherung an Silbersulfid als auch durch die Festphasenextraktion an Pb(II)-modifizierten Ionenaustauschmaterialien wird die Identifizierung unbekannter organischer Schwefelverbindungen in stark belasteten Proben erheblich erleichtert. Beide Methoden bilden als einfache und leistungsfähige Techniken wirkungsvolle Ergänzungen zu bereits etablierten Anreicherungsverfahren. Neben der Identifizierung und Analyse können die Techniken ebenfalls zur Entfernung von schwefelhaltigen Substanzen aus verschiedenen Matrizes dienen. Anwendungsmöglichkeiten der entwickelten Methoden bestehen neben der Umweltanalytik auch in der Lebensmittelchemie.