Oxidation of aqueous bromide into reactive, gas-phase bromine species has been of interest since the 1980’s, when the presence of bromine in the Arctic boundary layer was linked to ozone depletion events. We have investigated two different mechanisms for Br2 release from sea ice. We have shown that nitrate in sea ice can photolyze to produce OH, which can go on to form gas-phase Br2. This reaction is analogous to a known reaction that occurs in the aqueous phase. We have also investigated Br2 production from a heterogeneous reaction between gas-phase ozone and sea ice/seawater. We have determined ozone’s reactive uptake coefficient, and have shown how it varies with temperature, bromide concentration, ozone concentration and acidity. We have been able to decouple the bulk aqueous chemistry that occurs from the Langmuir-Hinshelwood surface chemistry, and quantify the relative contribution of each.

Oxidation of aqueous bromide into reactive, gas-phase bromine species has been of interest since the 1980’s, when the presence of bromine in the Arctic boundary layer was linked to ozone depletion events. We have investigated two different mechanisms for Br2 release from sea ice. We have shown that nitrate in sea ice can photolyze to produce OH, which can go on to form gas-phase Br2. This reaction is analogous to a known reaction that occurs in the aqueous phase. We have also investigated Br2 production from a heterogeneous reaction between gas-phase ozone and sea ice/seawater. We have determined ozone’s reactive uptake coefficient, and have shown how it varies with temperature, bromide concentration, ozone concentration and acidity. We have been able to decouple the bulk aqueous chemistry that occurs from the Langmuir-Hinshelwood surface chemistry, and quantify the relative contribution of each.

Water is of interest for understanding the formation history and habitability of past and present solar system environments. It also has potential as a resource - when split to its constituent oxygen and hydrogen - both in space and on the Earth. Determining the sources, evolution, and eventual fate of water on bodies easily reachable from Earth, especially Earth's moon, is thus of high scientific and exploration value to the private sector and government space agencies. Understanding how to efficiently split water with solar energy has potential to launch a hydrogen economy here on Earth and to power spacecraft more sustainably to far away destinations. To address the fundamental interactions of water with important surfaces relevant to space exploration and technology development, temperature programmed desorption (TPD) and water photolysis experiments under well controlled adsorbate coverages have been carried out and are described in detail in this thesis. TPD experiments under ultra-high vacuum (UHV) conditions were conducted on lunar surrogate materials and genuine lunar samples brought to Earth by the Apollo program. The TPD's were conducted to determine the desorption activation energies of water chemisorbed directly to the powder surfaces, knowledge of which can improve existing models of water evolution on Earth's moon and aid in interpreting data collected by spacecraft-based investigations at the Moon. The TPD experiments of molecular water interacting with two lunar surrogates (micronized JSC-1A and albite) in ultra-high vacuum revealed water desorption during initial heating to 750 K under ultra-high vacuum. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) indicated possible water formation during the initial heating via recombinative desorption of native hydroxyls above 425 ± 25K. Dissociative chemisorption of water (i.e., formation of surface hydroxyl sites) was not observed on laboratory time scales after controlled dosing of samples (initially heated above 750 K) with 0.2 - 500 L exposures of water. However, pre-heated samples of both types of surrogates were found to have a distribution of molecular water chemisorption sites, with albite having at least twice as many as the JSC-1A samples by mass. A fit to the TPD data yields a distribution function of desorption activation energies ranging from ~0.45 eV to 1.2 eV. Using the fitted distribution function as an initial condition, the TPD process was simulated on the timescale of a lunation. A preview of these results and their context was published in Icarus (2011) 213, 64, doi: 10.1016/j.icarus.2011.02.015 by lead author Charles Hibbitts and the full treatment of the results from the TPD on lunar surrogates (presented here in Chapter 2) has been published in the Journal of Geophysical Research – Planets (2013) 118, 105, doi: 10.1002/jgre.20025 by lead author Michael J Poston. The desorption activation energies for water molecules chemisorbed to Apollo lunar samples 72501 and 12001 were determined by temperature programmed desorption (TPD) experiments in ultra-high vacuum. A significant difference in both the energies and abundance of chemisorption sites was observed, with 72501 retaining up to 40 times more water (by mass) and with much stronger interactions, possibly approaching 1.5 eV. The dramatic difference between the samples may be due to differences in mineralogy, surface exposure age, and contamination of sample 12001 with oxygen and water vapor before it arrived at the lunar sample storage facility. The distribution function of water desorption activation energies for sample 72501 was used as an initial condition to mathematically simulate a TPD experiment with the temperature program matching the lunar day. The full treatment of the TPD results from these two lunar samples (presented here in Chapter 3) has been submitted with the title "Water chemisorption interactions with Apollo lunar samples 72501 and 12001 by ultra-high vacuum temperature programmed desorption experiments" to Icarus for publication in the special issue on lunar volatiles by lead author Michael J Poston. A new ultra-high vacuum system (described in Chapter 4) was designed and constructed for planned experiments examining the possible formation of hydrated species, including water, from interaction of solar wind hydrogen with oxygen in the lunar regolith and to examine the effects of the active radiation environment on water adsorption and desorption behavior on lunar materials. This system has been designed in close collaboration with Dr. Chris J Bennett. An examination of a unique system for water photolysis - zirconia nanoparticles for hydrogen production from water with ultra-violet photons - was performed to better understand the mechanism and efficiency of water splitting on this catalyst. Specifically, formation of H₂ from photolysis of water adsorbed on zirconia (ZrO₂) nanoparticles using 254 nm (4.9 eV) and 185 nm (6.7 eV) photon irradiation was examined. The H₂ yield was approximately an order of magnitude higher using monoclinic versus cubic phase nanoparticles. For monoclinic particles containing 2 monolayers (ML) of water, the maximum H₂ production rate was ~0.4 µmole hr⁻¹ m⁻² using 185 + 254 nm excitation and a factor of 10 lower using only 254 nm. UV reflectance reveals that monoclinic nanoparticles contain fewer defects than cubic nanoparticles. A H₂O coverage dependence study of the H₂ yield is best fit by a sum of interactions involving at least two types of adsorbate-surface complexes. The first dominates up to ~0.06 ML and is attributed to H₂O chemisorbed at surface defect sites. The second dominates at coverages up to a bilayer. H₂ formation is maximum within this bilayer and likely results from efficient energy transfer from the particle to the interface. Energy transfer is more efficient for the monoclinic ZrO₂ nanoparticles and likely involves mobile excitons. These results (presented in Chapter 5) have been submitted with the title "UV Photon-Induced Water Decomposition on Zirconia Nanoparticles" for publication in the Journal of Physical Chemistry C by lead author Michael J Poston. This paper has been reviewed and will be accepted after minor modification.

Radical chemistry has always been a very active area of research. This is due to the fact that radicals are both very numerous in variety and very reactive. A radical is any chemical species that possesses one or more unpaired electrons. These unpaired electrons usually lead to the extremely reactive characteristics of the chemical species. This reactivity can be beneficial; this is true in the case of polymer chemistry. For instance, some plastics are synthesized through a radical chain reaction. In addition, radicals are used in the synthesis of novel organic compounds with the goal of creating new pharmaceuticals. Radical reactivity can be detrimental as well; radicals have been implicated in a number of ailments including heart disease and cancer. One particular view of cancer cells is that their DNA is somehow mutated; a radical could cause this mutation. In fact, one radical species in particular is known to oxidize DNA, the hydroxyl radical.Unfortunately, the electronic structures of most radicals do not lend themselves to direct study by modem spectroscopic methods. Recently, researchers have discovered that hydroxyl radical, being very reactive in nature, easily complexes with other species. If these complexes are spectrosopically active, then we can study the radical reactivity indirectly through a "reporter" molecule. One such approach uses the transient visible absorbance of the complexes of hydroxyl radical with the thiocyanate anion. In addition, there is other experimental evidence that suggests that thiocyanate anion complexes with other radicals as well. These experiments have been very successful in improving our understanding of radical chemistry, but very little is known about the electronic structure or connectivities of these complexes.Our research is comprised of a systematic theoretical study of the structure, vibrational frequencies, and spectroscopic properties of complexes of hydroxyl radical with thiocyanate anion. In addition, we will investigate the structures, vibrational frequencies, and spectroscopic properties of complexes of thiocyanate anion and other radical species.The ultimate goal of our research is to determine the feasibility of utilizing thiocyanate anion as an LFP reporter for radical species other than hydroxyl radical.Our theoretical approach is based in computerized, mathematical models of the properties of the species being studied, based on quantum mechanics and density functional theory as implemented in the computational chemistry software Gaussian 03. Our study includes calculations that provide the energies, optimized geometry, vibrational frequencies, charge and spin densities, and other properties of the various species. This consists of the various isolated radicals and anions, complexes, transitions states, pre-reactive complexes, and structural isomers. / Department of Chemistry

Persistent organic pollutants (POPs) are organic compounds of anthropogenic origin that have been linked to the development of cancer, neurobehavioural impairment, and immune system biochemical alterations. These chemicals have various industrial applications as well as acting as pesticides. Dioxins and furans are some of these compounds that are unintentionally produced in combustion and industrial processes. By definition these compounds have 4 common qualities: they are highly toxic, they are resistant to environmental degradation, they are introduced into the air and water where they travel long distances, and they accumulate in fatty tissues. Photochemical degradation is a method that has been extensively researched in the last few decades. In the aqueous phase it has already been shown to be able to degrade a number of refractory organics, such as dioxins and furans. The ultimate products of this process tend to be carbon dioxide, water, and mineral anions. Air phase work has been also gaining attention in recent decades as a possible alternative to incineration methods in air pollution control. The advantages of photochemical degradation processes are that they can be initiated at low temperatures, are relatively low cost compared to incineration processes, environmentally benign, and have the potential for quick and complete degradation of organic compounds. The main aim of the research is to investigate the photochemical degradation potential of PCDD/ PCDFs in gaseous air streams as a potential air pollution control technology. In order to do this, the photodegradation reaction kinetics were determined for chlorobenzene as a suitable surrogate for PCDD/PCDFs. Three different photodegradation schemes were employed: direct photolysis, UV/O3, and UV/H2O2. In addition, ozonolysis reaction rates were also determined to evaluate the effects of on the overall photodegradation rates for the UV/O3 process. Factors such as humidity levels and temperature were investigated to determine their effects on degradation rates. Temperature and humidity were not greatly influential on the degradation rates of direct photolysis. The degradation rate of chlorobenzene at a temperature of 100°C and high humidity was noticeably reduced, but unchanged at the 10% RH and 60% RH levels for all temperatures. Ozonolysis of chlorobenzene was negligible at 30°C for all humidity levels. Ozonolysis reactions at the 60°C and 100°C levels were higher than direct photolysis rates and in the 100°C case exceeded the UV/O3 degradation rates. Ozone coupled with UV experiments proved to be the most destructive at the low temperature of 30°C and molar ratio of 10:1 ozone to chlorobenzene. There was a clear and positive relationship between the amount of ozone present in the reactor and the degradation rate. At lower ozone to chlorobenzene molar ratios the degradation rates were not much higher than those for direct photolysis of ozone. The 5:1 molar ratio saw a significant increase in degradation rates over the photolysis rates. The fastest degradation rate was achieved for the 10:1 molar ratio and high humidity, which was over 10 times the rate of direct photolysis. In addition, humidity had a noticeably significant positive effect in these reactions. The effect of temperature on the UV/ozone reaction scheme was determined for the 5:1 ozone to chlorobenzene ratio. Temperature had an interesting effect on the degradation rates at higher temperatures. As the reactor temperature increased, the degradation rates from ozonolysis and UV/O3 began to converge at 60°C, ultimately leading to the ozonolysis reaction being faster than the UV/O3. Exploratory experiments for the H2O2 scheme were performed. H2O2 had a positive influence on the degradation rate of chlorobenzene and was about 26% higher than the direct photolysis rates. However for similar conditions, the UV/O3 process had higher degradation rates as was expected from the difference in absorption values between ozone and hydrogen peroxide.

Sulfite oxidising enzymes are found in all forms of life and play an important role in detoxification of sulfite produced through biochemical processes. All known sulfite oxidising enzymes share a common molybdenum active site. The sulfite dehydrogenase (SDH) from the soil bacterium Starkeya novella differs from the vertebrate sulfite oxidases (SO) in that the heme and Mo subunits are tightly associated rather than connected by a flexible hinge. This structural integrity makes SDH an ideal model enzyme for the study of enzymatic sulfite oxidation without the complications of structural changes underlying catalysis. In human sulfite oxidase (HSO) the substitution of a conserved active site amino acid residue, Arg-160 for Gln, results in a lethal disease. A number of independent studies have been carried out in order to understand the effects of this substitution on catalysis in both human (HSO) and chicken sulfite oxidising enzymes (CSO). The focus of this work is the analogous residue in SDH, Arg 55. A number of active site substitutions have been investigated, including SDHR55Q, an analogous substitution to the lethal mutation identified in humans. In addition, the properties of the Arg residue have also been probed using a substitution to a hydrophobic residue, Met (SDHR55M) and a substitution to the positively charged Lys (SDHR55K). A fourth active site substitution, SDHH57A, was also investigated as the crystal structure of this variant indicated that His-57 plays a role in stabilising the position of Arg-55 in SDH. It was of interest to determine the effect of the instability in the position of Arg-55 on the catalytic parameters of the SDHH57A. The kinetic properties of the substituted enzymes were investigated using steady-state assays with cytochrome c as an electron acceptor. When the positive charge was lost in the case of SDHR55M and SDHR55Q, a dramatic increase in the KM (sulfite - app) of 2 – 3 orders of magnitude resulted. This indicates that the positive charge on Arg-55 is important for substrate binding. All the Arg-55 variants studied were found to have lower turnover numbers than the wild type, in particular, SDHR55Q was found to have a reduced kcat (108 s-1 vs 345 s-1 for SDHWT at pH 8). The changes in the Mo centre underlying the altered kinetic properties were investigated in detail using EPR spectroscopy of the intermediate MoV oxidation state in SDHR55Q and SDHH57A. Similar to what has been noted for HSOR160Q, a sulfate blocked form was observed at pH 6 using pulsed EPR experiments, suggesting that this substitution causes an inhibition of the hydrolysis step required to release the reaction product, sulfate. This could be a further reason for the poor catalytic activity of SDHR55Q, in particular, a reason for the low turnover rate of this variant. Unlike what was noted in HSOR160Q, where the substituted enzyme showed a dramatic decrease in rate of intramolecular transfer by three orders of magnitude compared to HSOWT, the rate of electron transfer was found to be 3 times faster in SDHR55Q relative to the wild type enzyme. These results indicate that Arg-55 is not involved in the pathway of electron transfer between the Mo and heme centres, but rather assists with the the docking of the heme group in HSO. As this process is not required in SDH, our results suggest that intramolecular electron transfer (IET) in HSOR160Q decreases because it is crucial for docking of the heme domain. Through potentiometric redox titrations, the effect of the active site amino acid substitutions on both the Mo and Fe redox potentials was investigated. No significant change was determined for the MoVI/V redox potentials, however, the heme potentials for SDHWT and SDHR55K were 40 mV higher than those of the other variants, with the lowest potentials belonging to SDHR55M and SDHH57A. Of further interest was that the MoVI/V couple is significantly lower than the heme couple (175 mV vs 240 mV respectively) in SDHWT. It appears that the positive charge of the Arg is important in regulating the heme redox potentials and could thereby contribute to modulating enzymatic activity. When SDH was immobilised on a modified pyrolytic graphite electrode, stable and high catalytic currents were observed, indicating facile heterogeneous electron transfer between the enzyme and the electrode. This good electron transfer allowed the catalytic properties of SDH and its substituted enzymes to be investigated as a function of potential. A pH dependence ( 59 mV/pH) in the catalytic operating potential was noted for SDHWT and SDHR55K, which appears to follow the pH dependence of the MoVI/V couple. This catalytic potential is pH-independent in the R55M and H57A variants, where the catalytic operating potentials appeared to follow the FeIII/II redox couple. It is proposed that two distinct pathways of electron transfer from the Mo centre to the electrode are likely to exist. The first is direct transfer from the Mo centre to the electrode at lower potential (~ 175 mV) while the second proceeds via the heme group (320 mV). The pathway followed is determined by the oxidation state of the heme group. A slight difference in the electron transfer rates of these two processes was seen, with direct transfer (from Mo) being the faster, which accounts for the unusual peak shape noted in the voltammogram for SDHWT at high sulfite concentrations, where the rate of catalytic activity slows at a higher potentials despite the greater thermodynamic driving force. This work provides new insights into the mechanism of enzymatic sulfite oxidation. Arg-55 has been shown to play an important role in the catalytic functioning of SDH in both substrate affinity and product release. Unlike what has been previously proposed, Arg-55 does not play a part in the pathway of electron transfer, but is rather involved in the regulation of the redox potentials of the metal centres in the enzyme.

Thesis (M.S.)--University of Alabama at Birmingham, 2010. / Title from PDF t.p. (viewed June 30, 2010). Includes bibliographical references (p. 19-22).

De nos jours, l'émergence de produits pharmaceutiques dans l'environnement aquatique et terrestre a été une préoccupation majeure. Ils ont été détectés dans les stations d'épuration, les sédiments et les sols ainsi qu'à la surface et dans l'eau potable. Jusqu'à présent, il y a peu d'informations dans la littérature sur le devenir de ces composés lorsqu'ils sont exposés à la lumière solaire dans les différents compartiments environnementaux. Dans le cadre de ce travail, notre objectif est l’étude de comportement des antibiotiques de la famille des Sulfonamides : Sulfaméthoxazole (STZ), Sulfathiazole (STL), Sulfamethazine (STN) et Hydrochlorothiazide (HCD) dans des solutions aqueuses lorsqu'ils sont exposés à la lumière solaire. Nous nous sommes principalement intéressés à l’étude cinétique en évaluant le rendement quantique de dégradation ainsi que l'effet de divers paramètres tels que la concentration en oxygène, le pH et la présence d'ions inorganiques. Nous nous sommes également intéressés à l'élucidation des principaux sous-produits intermédiaires. De nombreuses informations sont disponibles sur la stabilité et le devenir des composés d'origine et beaucoup moins sur leurs produits de transformation. Ces derniers peuvent présenter un niveau de toxicité plus élevé que le substrat précurseur et doivent ainsi être identifiés et analysés. L'élucidation de la structure a été obtenue en utilisant les techniques HPLC / ESI / MS et HPLC / ESI / MS2 en modes négatif et positif et par l'étude complète des différentes voies de fragmentation. Les principaux processus photochimiques impliqués sont : i) la scission du pont par photohydrolyse, ii) l'hydroxylation sélective de la partie aromatique iii) le processus de désulfonation et iiii) dans le cas de HCD une réaction de déchloration. Un mécanisme photochimique a été proposé sur la base des études cinétiques et analytiques. / Nowaday the emergence of pharmaceuticals in the aquatic and terrestrial environment have been a major concern. They have been detected in sewage-treatment plants, sediments, and soils as well as at surface and drinking water. So far, there is limited information in the literature on the fate of these compounds once they are exposed to solar light in the various environmental compartments. In the present work we have been interested in studying the behavior of antibiotics from Sulfonamide family: Sulfamethoxazole (STZ), Sulfathiazole (STL), Sulfamethazine (STN) and Hydrochlorothiazide (HCD) in aqueous solutions upon exposure to simulated solar light. We mainly concentrate our effort on the kinetic studies by evaluating the degradation quantum yield as well as the effect of various parameters such as oxygen concentration, pH and the presence of inorganic ions. The main effect was observed by molecular oxygen parameter. We also make an important effort in the elucidation of the main intermediate and stable by-products. A lot of information is available on the stability and fate of parent compounds and not so many on their transformation products. These may present a toxicity level higher than the precursor substrate and should be identified and analysed. The chemical structure elucidation was obtained by using the HPLC/ESI/MS and HPLC/ESI/MS2 techniques in negative as well as positive modes and through the complete study of the various fragmentation pathways. The main involved photochemical processes were identified as i) the scission of the bridge through a photohydrolysis process, ii) selective hydroxylation of the aromatic moiety iii) Desulfonation process and iiii) in the case of HCD to dechloration reaction. A mechanism was then proposed in the light of the kinetics and analytical studies.

Os contaminantes emergentes são considerados compostos onipresentes em águas, portanto investigar a degradação e comportamento dessas substâncias torna-se necessária, pois é reportado que estes compostos causam efeitos adversos em seres vivos. O composto 2-(tiocianometiltio) benzotiazol (TCMTB), considerado um contaminante emergente, é amplamente empregado na indústria do couro como biocida com a finalidade de inibir o desenvolvimento de microrganismos na pele. Sendo assim, o objetivo do presente trabalho foi estudar a degradação do contaminante emergente TCMTB, por meio das técnicas de fotólise direta com radiação UV, radiação solar e oxidação com ozônio. Experimentos de fotólise direta do TCMTB, em soluções aquosas com diferentes concentrações, em efluente do processo de remolho e efluente simulado do remolho, foram conduzidos em reator com lâmpada de vapor de mercúrio (250 W). O teste de hidrólise foi realizado protegido da luz, a temperatura ambiente com diferentes concentrações do TCMTB para observar o comportamento do contaminante na ausência de luz. O maior coeficiente de absorção molar foi medido e identificado em 220 e 280 nm como 20489 e 11317 M-1 cm-1, respectivamente, para pH 5,0. Os resultados experimentais da fotodegradação mostraram que TCMTB foi rapidamente degradado por fotólise direta em soluções aquosas em 30 min de tratamento fotolítico. Os resultados do estudo do pH, demonstraram que pH interfere no processo fotoquímico, uma vez que em condições alcalinas o composto é mais estável e a taxa de fotodegradação diminui. Os ensaios com o efluente do processo de remolho mostraram que a degradação do TCMTB tem comportamento semelhante às soluções aquosas. O efluente simulado do remolho mostrou que uma alta concentração do contaminante leva a um maior tempo de irradiação de luz para a degradação. A aplicação de luz natural evidenciou degradação mais lenta, mas ainda assim, foi possível observar degradação de até 96% para a concentração de 6 mg L-1 em 420 min. A utilização do oxidante ozônio como tratamento, alcançou 40% de remoção do contaminante em 30 min, assinalando a alta estabilidade do composto. Portanto, este trabalho aponta o potencial do uso de fotólise direta (luz v artificial), ou radiação solar (luz natural) para a degradação de contaminantes emergentes como o 2 (tiocianometiltio) benzotiazol (TCMTB). / Emerging contaminants are considered omnipresent compounds in water, thus investigate the degradation and behavior of these substances becomes necessary as it is reported that these compounds cause adverse effects on living beings. The 2- (thiocyanomethylthio) benzothiazole compound (TCMTB), considered an emerging contaminant, is widely used in the leather industry as a microbicide for the purpose of inhibiting the development of microorganisms in the skin and leather. In this context, the purpose of the present work was to study the degradation of the emerging contaminant TCMTB by direct photolysis with UV radiation, solar radiation and ozone. Experiments of direct photolysis of the TCMTB in aqueous solutions with different concentrations, in the effluent from the soaking process were conducted in a reactor with mercury vapor lamp (250 W). The hydrolysis test was performed protected from light at room temperature with different concentrations of TCMTB to observe the behavior of the contaminant in the absence of light. The highest molar absorption coefficient was measured and identified at 220 and 280 nm as 20489 and 11317 M-1 cm -1, respectively, at pH 5.0. The experimental results of photodegradation showed that TCMTB was rapidly degraded by direct photolysis in aqueous solutions in 30 min of photolytic treatment. The results of the pH study showed that pH interfered in the photochemical process, since under alkaline conditions the compound is more stable and the photodegradation rate decreases. Assays of the direct photolysis in effluent from the soaking process have shown that TCMTB degradation behaves similarly to aqueous solutions. The direct photolysis of the the simulated effluent from the soaking showed that a high concentration of the contaminant leads to a longer time of light irradiation for degradation. The application of natural light evidenced slower degradation, however, it was possible to observe degradation of up to 96% for the 6 mg L-1 concentration with 420 min. The use of the ozone oxidant as a treatment, achieved 40% removal of the contaminant for 30 min of treatment, indicating the high stability of the compound. Therefore, this work highlights the potential of the use of direct photolysis (artificial light), or solar radiation (natural light) for the vii degradation of emerging contaminants such as 2 (thiocyanomethylthio) benzothiazole (TCMTB).

abstract: N-Nitrosodimethylamine (NDMA), a probable human carcinogen, has been found in clouds and fogs at concentration up to 500 ng/L and in drinking water as disinfection by-product. NDMA exposure to the general public is not well understood because of knowledge gaps in terms of occurrence, formation and fate both in air and water. The goal of this dissertation was to contribute to closing these knowledge gaps on potential human NDMA exposure through contributions to atmospheric measurements and fate as well as aqueous formation processes. Novel, sensitive methods of measuring NDMA in air were developed based on Solid Phase Extraction (SPE) and Solid Phase Microextraction (SPME) coupled to Gas Chromatography-Mass Spectrometry (GC-MS). The two measuring techniques were evaluated in laboratory experiments. SPE-GC-MS was applicable in ambient air sampling and NDMA in ambient air was found in the 0.1-13.0 ng/m3 range. NDMA photolysis, the main degradation atmospheric pathway, was studied in the atmospheric aqueous phase. Water soluble organic carbon (WSOC) was found to have more impact than inorganic species on NDMA photolysis by competing with NDMA for photons and therefore could substantially increase the NDMA lifetime in the atmosphere. The optical properties of atmospheric WSOC were investigated in aerosol, fog and cloud samples and showed WSOC from atmospheric aerosols has a higher mass absorption efficiency (MAE) than organic matter in fog and cloud water, resulting from a different composition, especially in regards of volatile species, that are not very absorbing but abundant in fogs and clouds. NDMA formation kinetics during chloramination were studied in aqueous samples including wastewater, surface water and ground water, at two monochloramine concentrations. A simple second order NDMA formation model was developed using measured NDMA and monochloramine concentrations at select reaction times. The model fitted the NDMA formation well (R2 >0.88) in all water matrices. The proposed model was then optimized and applied to fit the data of NDMA formation from natural organic matter (NOM) and model precursors in previously studies. By determining the rate constants, the model was able to describe the effect of water conditions such as DOC and pH on NDMA formation. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2016