Iron (Fe) speciation is important for many biogeochemical processes. The high abundance and limited solubility of Fe(III) are responsible for the widespread occurrence of Fe(III) minerals in the environment. Co-precipitation and adsorption onto mineral surfaces limits the free concentrations of compounds such as arsenate (As(V)), Fe(III) and, phosphate (P(V)). Mineral dissolution, on the other hand, might lead to elevated concentrations of these compounds. Fe speciation is strongly affected by natural organic matter (NOM), which suppresses hydrolysis of Fe(III) via complexation. It limits the formation of Fe(III) minerals and Fe(III) co-precipitation. This thesis is focused on interactions between Fe(III) and NOM as well as their impact on other elements (i.e. As(V) and P(V)). X-ray absorption spectroscopy (XAS) was used to obtain molecular scale information on Fe and As speciation. This was complemented with infrared spectroscopy, as well as traditional wet-chemical analysis, such as pH and total concentration determinations. Natural stream waters, soil solutions, ground water and soil samples from the Krycklan Catchment, in northern Sweden, were analyzed together with model compounds with different types of NOM. A protocol based on ion exchange resins was developed to concentrate Fe from dilute natural waters prior to XAS measurements. Iron speciation varied between the stream waters and was strongly affected by the surrounding landscape. Stream waters originating from forested or mixed sites contained both Fe(II, III)-NOM complexes and precipitated Fe(III) (hydr)oxides. The distribution between these two pools was influenced by pH, total concentrations and, properties of NOM. In contrast, stream waters from wetland sites and soil solutions from a forested site only contained organically complexed Fe. Furthermore, the soil solutions contained a significant fraction Fe(II)-NOM complexes. The soil samples were dominated by organically complexed Fe and a biotite-like phase. Two pools of Fe were also identified in the ternary systems with As(V) or P(V) mixed with Fe(III) and NOM: all Fe(III) was complexed with NOM at low total concentrations of Fe(III), As(V) and/or P(V). Hence, Fe(III) complexation by NOM reduced Fe(III)-As(V)/P(V) interactions at low Fe(III) concentrations, which led to higher bioavailability. Exceeding the Fe(III)-NOM complex equilibrium resulted in the occurrence of Fe(III)-As(V)/P(V) (co-)-precipitates.

Climate change is predicted to be the most pronounced in high latitude ecosystems, however very little is known about their vulnerability to the projected warmer temperatures. In particular, natural organic matter (NOM) in the high latitude cryosphere which includes dissolved organic matter (DOM) and cryoconite organic matter (COM) from glaciers and soil organic matter (SOM) in permafrost, is highly susceptible to climate change which may lead to severe consequences on both local and global carbon biogeochemical cycles. Examination of DOM in glacier ice by a novel 1H nuclear magnetic resonance (NMR) water suppression pulse sequence at its natural abundance revealed and quantified the composition and the organic constituents in ice samples from Antarctica. 1H NMR spectra of samples from several glaciers were acquired and compared to the dominant fluorescent DOM fraction. This comprehensive approach showed that glacier ice DOM was mainly composed of small, labile biomolecules associated with microbes. Examination of the organic debris found on glacier surfaces (COM) from both Arctic and Antarctic glaciers were determined to be derived from microbes. Samples from Arctic glaciers were more chemically heterogeneous with small inputs of plant-derived material detected after targeted extractions. Therefore the COM carbon composition was determined to be dependent on the local glacier environment, suggesting a site specific contribution to the carbon cycle. Finally, the distribution of extracted branched glycerol dialkyl glycerol tetraether (GDGT)microbial membrane lipids and the deuterium incorporation of plant-wax n-alkane biomarkers extracted from dated permafrost SOM (paleosols) were independently applied for Canadian Arctic climate reconstruction during the last glacial maximum. Overall, the branched GDGT based temperature reconstructions from the Arctic paleosols reconstruct higher temperatures, likely when bacterial activity was optimal. The deuterium composition of the C29 n-alkane plant lipids appears to integrate an average annual signal. Further analysis by both non-selective NMR spectroscopic and targeted biomarker techniques on these paleosol samples revealed that the major vegetative sources from this paleoecosystem originated from woody and non-woody angiosperms. This thesis demonstrates several novel analytical characterization techniques, along with the major sources and composition of NOM in the cryosphere while demonstrating its use in paleoclimate applications.

In order to properly evaluate the ecological and human health risks of ZnO Manufactured nanomaterials (MNMs) released to the environment, it is critical to understand the likely transformation products in the wastewater treatment process and in soils receiving biosolids. To address this critical knowledge gap, we examined the transformation reactions of 30 nm ZnO MNMs in single component and multi-component systems, with phosphate and natural organic matter (NOM). We also assessed the influence of nano ZnO transformation on the bioavailability, and toxicity of ZnO transformation products to Triticum aestivum. The data revealed that ZnO MNMs react with phosphate at concentrations expected in wastewater and transform into two distinct morphological/structural phases. A micron scale crystalline zinc phosphate phase (hopeite), and a nano-sized phase that likely consists of a ZnO core with a Zn3(PO4)2 rich shell. Presence of NOM reduces particle aggregation and enhances stability, regardless of the sequence of ligands addition in the aging scenarios. The presence of phosphate and NOM also altered the bioavailability and reduced the toxicity of the ZnO MNMs to Triticum aestivum.

Environmental impact of fullerenes such as C60 and carbon nanotubes is of great concern due to the projection for widespread application and mass production in near future. Understanding their fate in the aqueous phase is prerequisite for accurate assessment of their ecotoxicological and human health effects upon unintended release to environment. This research addresses outstanding questions related to the behavior of fullerenes in natural and engineered water environments. Specifically, this research focuses on investigating: 1) the stability of fullerenes in the natural water, 2) interaction between fullerenes and natural organic matter (NOM), and 3) treatability of water stable fullerenes by conventional water treatment process. The experimental results suggested that NOM readily interacts with fullerenes leading to the formation of water stable fullerene suspensions. The adsorptive interaction between NOM and fullerenes was largely affected by NOM characteristics as well as water quality parameters. The fate of fullerenes in water environments was also greatly influenced by the types of fullerenes (e.g., single walled carbon nanotubes, multi-walled carbon nanotubes, and C60) and the pathway they are introduced into the aqueous phase. These water stable fullerene suspensions were found to be relatively well removed by conventional water treatment processes while the presence of NOM could negatively impact the removal efficiency. The outcomes of this study collectively imply that the dispersion of fullerenes in the natural water can occur beyond the level predicted only based on their extreme hydrophobicity and NOM plays a critical role on the fate of fullerenes both in natural and engineered water environments.

La contamination du milieu naturel, notamment des aquifères, par des hydrocarbures lourds de type HAP (Hydrocarbure Aromatique Polycyclique) se révèle être une pollution pérenne très difficile à traiter. La dépollution de ces sous-sols par un traitement in situ efficace et peu coûteux constitue encore aujourd’hui un challenge. Cette étude cible une technique de co-injection air-vapeur en zone saturée comme alternative aux techniques thermiques et chimiques en vigueur pour le traitement de cette catégorie d’hydrocarbures. Une première partie expérimentale introductive estime l’influence d’un simple traitement vapeur sur la libération de HAPs par les matrices de sol au sein de l’aquifère, montrant la nécessité de coupler à ce procédé une technique d’oxydation chimique. Si le front de vapeur permet de mobiliser totalement les composés légers, les concentrations des composés les plus lourds augmentent en phase dissoute (augmentation des fractions molaires des composés résiduels). Réalisées en milieu fermé, dans des conditions de température dictées par l’injection de vapeur (120 ̊C), des expériences en laboratoire ont permis de caractériser et de quantifier les réactions d’oxydation chimique mises en jeu. Les résultats démontrent une efficacité modérée de l’oxydation à moyenne température. Des sous-produits de réaction sont identifiables et quantifiables à compter de plusieurs semaines de réaction. A l’inverse l’étude met en évidence l’absence totale de minéralisation, démontrant que l’ana- lyse du CO2 ne peut renseigner sur l’évaluation du phénomène d’oxydation. Hormis la réactivité par oxydation, les conclusions de l’étude montrent que la technique favorise la sorption irréversible des composés organiques en surface des matrices de sol. Ces phénomènes de sorption sont très marqués en présence d’argile ou de matière organique naturelle dans le milieu et augmentent au cours du temps. La technique HPO se pose donc en traitement de soutien à l’injection de vapeur par oxydation mais surtout par stabilisation de la zone de contamination. Enfin nous nous sommes intéressés aux problématiques liées à l’injection d’eau chaude et de vapeur dans un sous-sol au travers d’expériences sur site. La technique d’injection de vapeur étant financièrement et énergétiquement coûteuse, des solutions techniques ont été proposées, appliquées et modélisées. Il en ressort une comparaison en bilans énergétiques pour différents modes d’injection, permettant de mieux appréhender les véritables besoins d’une telle technique. Parmi les paramètres influents, le rayon d’influence est un paramètre essentiel qui conditionne la distance entre chaque puits pour une efficacité optimale. Les résultats de l’étude démontrent que dans certains scénarios d’injection (injection à grande profondeur) le préchauffage de la zone d’étude par injection d’eau chaude couplé à un pompage en profondeur permettra d’accroître significativement le rayon d’influence et d’améliorer le bilan énergétique du traitement global. Les principaux résultats de la thèse sont comparés aux autres études sur l’injection de vapeur pour dégager les meilleures conditions d’application de cette technique, et mettre en évidence les verrous techniques ayant pu être levés au cours de la thèse. / PAHs are the largest, ubiquitous and carcinogenic environmental chemical groups. In a context of polluted soil remediation, today it is still a challenge to reach an effective in situ treatment. This study aims to evaluate as an alternative way the potential of a technology combining a thermal process (injection of steam) and a chemical process (co-injection of air) in the saturated zone. A first introductory experimental section considers the influence of a single steam treatment on the release of PAHs from soil matrices within the aquifer. Results prove the necessity of coupling a chemical oxidation technique with this process. If the steam front allows to recover light com- pounds, concentrations of heavier compounds in the dissolved phase are more important after the steam treatment (molar fractions of residual compounds increase). In order to study the fate of PAHs in polluted soils under medium temperature oxidation, numerous experiments in presence of soil spiked matrices were carried out in closed reactors. The catalytic potential of different mineral surfaces was investigated by studying reactivity of different PAHs. Results demonstrate that the efficiency of oxidation remains moderate. They suggest a lack of mineralization and reactions producing partly polycyclic aromatic compounds (PACs) with equivalent molecular weight as the initial contaminants. Along short term experiments (9 days), the major effect of heating is an increase in irreversible sorption of original compounds. Interestingly, this sorption mostly occurs in presence of natural organic matter and oxygen in the gas phase, suggesting a specific reactivity of the natural organic matter. In long term experiments (6 months), new oxygenated PACs were formed and remained fixed on the solid phase. Consequently, air oxidation catalyzed by minerals and natural organic matter may be a new pathway concerning PAH stabilization in soils. The steam injection technique is still considered as a costly technique. In this last part some technical solutions have been proposed, implemented and modelized. The economic aspect of some injection cases are compared, based on the results of a real field application and some general calculations regarding the costs of wells and energy. Among influential parameters, the radius of influence is a key parameter that determines the distance between each well for an optimum efficiency. The results of this study show that in some scenarios of injection (when the injection takes place in a deeper zone), a preheating phase can be an interesting option to reduce the financial costs of the technique. The main results of the thesis are compared with other steam injection studies to identify the best conditions for the technique application.

This diploma thesis is focused on coagulation of humic substances (HS) and BSA (Bovine Serum Albumin) protein which was chosen as a representative of proteins contained in AOM (Algal Organic Matter). Additionally, possible interactions between these compounds were also investigated. It was found that the optimal dosage of coagulant is much higher for HS compared to BSA. The best removal of both HS and BSA was reached in slightly acidic pH range and it is attributed mainly to charge neutralization and adsorption mechanisms. The maximum removal rate was 70 % for humic substances and 80 % for BSA. The results show that BSA has a positive effect on coagulation of HS (resulting in a lower coagulant demand) and vice versa while BSA was removed more efficiently than HS. The existence of interactions between BSA and humic substantces during coagulation was demonstrated in certain pH ranges and it can occur even without the presence of coagulant. These interactions are highly dependent on pH that determines charge properties (and hence reactivity) of organic matters. Finally, the comparison of BSA and cyanobacterial proteins shows that their behavior during coagulation is similar. Consequently, BSA can be used as a model compound representing AOM proteins, especially their high molecular weight fraction....

Radionuclides, 129I and 239,240Pu, are major products or by-products of nuclear fission and among the top risk drivers for waste disposal at the Savannah River Sites (SRS) and Rocky Flats Environmental Technology Sites (RFETS), respectively, due to their perceived mobility in the environment, excessive inventory, toxicity, and long half-life. The objective of this study is to investigate the role of natural organic matter in retarding or facilitating the migration of 129I and 239,240Pu in the Department of Energy (DOE) sites. Measurements of 127I and 129I in humic acids (HAs) and fulvic acids (FAs) obtained by five successive alkaline, two glycerol and one citric acid-alkaline extractions, demonstrated that these extractable humic substances (HS) together account for 54-56 percent and 46 percent of the total 127I and 129I in the soil, respectively. The variations among 127I and 129I concentrations, isotopic ratios (129I/127I), chemical properties of all these humic substances indicated iodine was bound to a small-size aromatic subunit (~10 kDa), while the large-size subunit (~90 kDa), which likely linked the small-size unit through some weak chemical forces, determined the relative mobility of iodine bound to organic matter. Soil resuspension experiments simulating surface runoff or stormflow and erosion events were conducted with soils collected from SRS. Results showed that 72-77 percent of the newly-introduced I- or IO3- were irreversibly sequestered into the organic-rich soil, while the rest was transformed into colloidal and dissolved organo-iodine by the soil. The resulting iodine remobilization contradicts the conventional view that considers only I- or IO3- as the mobile forms. Quantitative structure analysis by 13C DPMAS NMR and solution state 1H NMR on these humic substances indicate that iodine is closely related to the aromatic regions containing esterified products of phenolic and fomic acid or other aliphatic carboxylic acids, amide functionalities, quinone-like structure activated by electron-donating groups (e.g., NH2) or hemicelluloses-lignin-like complex with phenyl-glycosidic linkage. The micro-molecular environment, such as the hydrophobic aliphatic periphery hindering the active aromatic cores and the hydrophilic polysaccharides favoring its accessibility towards hydrophilic iodine species, play another key role in the interactions between iodine and SOM. NMR spectra of the colloidal organic Pu carrier which can potentially be released from the soil during the surface runoff or stormflow showed Pu was transported, at sub-pM concentrations, by a cutin-derived soil degradation products containing siderophore-like moieties and virtually all mobile Pu.

The fast growing production of carbon based nanomaterials (CNMs) and their potential widespread use in consumer products raise concerns regarding their potential risks to human health and ecosystems. The present study investigated the role of photochemical transformation and natural organic matter (NOM) in the fate, transport, and toxicity of fullerenes and carbon nanotubes (CNTs) in natural aquatic systems, providing fundamental information for risk assessment and management. Photochemical transformation of aqueous fullerene nanoparticles (nC60) and CNTs occurs at significant rates under UVA irradiation at intensity similar to that in sunlight. The transformation processes are mediated by self-generated ROS, resulting in changes of surface structure depending on the initial surface oxidation state of CNMs. UVA irradiation leads to oxygenation of nC60 surface and decarboxylation of carboxylated multi-walled carbon nanotubes (COOH-MWNTs). The environmental transport of CNMs is significantly affected by their surface chemistry, concentration and species of electrolytes, and concentration and properties of co-existing NOM. In electrolyte solutions without NOM, the mobility of CNMs is largely decided by their surface chemistry, primarily the oxygen-containing functional groups. In NaCl solutions, UVA irradiation remarkably enhanced the mobility of nC60; conversely, it reduced nC60 stability in CaCl2 solutions. The mobility of COOH-MWNTs in NaCl solutions correlated well with the abundance of surface carboxyl groups. Humic acid, once adsorbed on the nC60 surface, can significantly enhance its stability through steric hindrance. The extent of stabilization depends on the amount and properties of humic acid adsorbed. Humic acid has limited adsorption on UVA-irradiated nC60. Soil humic acid is more efficient in stabilizing nC60 than aquatic humic acid due to its higher molecular weight. Humic acid immobilized onto the silica surface can potential enhance or hinder nC60 deposition, depending on the complex interplay of attractive and repulsive forces. MWNTs are more toxicity to bacteria, Escherichia coli, than COOH-MWNTs due to their higher bioavailability and oxidative capacity. Surface oxidation induced by •OH reduced the toxicity of MWNT while reactions with •OH have little effect on the COOH-MWNT toxicity. Antioxidants such as glutathione can effectively inhibit the antibacterial activity of MWNTs.

The Suwannee River natural organic matter (SRNOM) was fractionated by preparative size-exclusion chromatography (SEC) into seven molecular weight (MW) fractions. The SRNOM and its MW fractions were subsequently analyzed for their concentrations of acidic functional groups by direct titrations, average MWs and MW distributions by semi-analytical SEC, and charge-to-MW distributions by capillary electrophoresis. Carboxyl concentrations in the MW fractions were inversely proportional to their average MWs. Conversely, the phenolic concentrations, though smaller than the carboxyl concentrations, were proportional to average MWs. Hysteresisthe non-overlap between sequential forward and reverse titrationswas observed for the SRNOM and its MW fractions, where the reverse titrations predicted a greater concentration of carboxylic acid groups than the forward titration. Because hysteresis is thought to be caused by the base-catalyzed hydrolysis of esters, this suggests that ester groups in the SRNOM are distributed over all MWs. Data for direct titrations, MW distributions, and capillary electrophoresis were evaluated by a computational scheme that solves for the most probable distribution of acidic functional groups and charges on solutes in the SRNOM and the MW fractions as a function of pH. Depending on the MW ranges of the samples, solutes in the SRNOM and the MW fractions are predicted to have from one to a maximum of 25 carboxyl groups per solute. Most phenolic groups are predicted to be on solutes that have a minimum of two carboxyl groups. At low pH, all samples have high relative abundances of solutes with the lowest charges. The charges of solutes are predicted to increase with increasing pH due to the sequential ionization of acidic functional groups. Depending on the MW ranges of the samples, the maximum probable charges of solutes in the SRNOM and the fractions at high pH are -12 to -30. By knowing the most probable distribution of charge and abundances of acidic functional groups, researchers will make better estimates of thermodynamic parameters and models that describe equilibria between metals and natural organic matter in the environment.

The objective of this research was to develop fluorescence-based tools that are suitable for performing rapid, accurate and direct characterization of natural organic matter (NOM) and colloidal/particulate substances present in natural water. Most available characterization methods are neither suitable for characterizing all the major NOM fractions such as protein-, humic acid-, fulvic acid- and polysaccharide-like substances as well as colloidal/particulate matter present in natural water nor are they suitable for rapid analyses. The individual and combined contributions of these NOM fractions and colloidal/particulate matter present in natural water contribute to membrane fouling, disinfection by-products formation and undesirable biological growth in drinking water treatment processes and distribution systems. The novel techniques developed in this research therefore, provide an avenue for improved understanding of these negative effects and proactive implementation of control and/or optimization strategies. The fluorescence excitation-emission matrix (EEM) method was used for characterization of NOM and colloidal/particulate matter present in water. Unlike most NOM and colloidal/particulate matter characterization techniques, this method can provide fast and consistent analyses with high instrumental sensitivity. The feasibility of using this method for monitoring NOM at very low concentration levels was also demonstrated with an emphasis on optimizing the instrument parameters necessary to obtain reproducible fluorescence signals. Partial least squares regression (PLS) was used to develop calibration models by correlating the fluorescence EEM intensities of water samples that contained surrogate NOM fractions with their corresponding dissolved organic carbon (DOC) concentrations. These fluorescence-based calibration models were found to be suitable for identifying/monitoring the extent of the relative changes that occur in different NOM fractions and the interactions between polysaccharide- and protein-like NOM in water treatment processes and distribution systems. Principal component analysis (PCA) of fluorescence EEMs was identified as a viable tool for monitoring the performance of biological filtration as a pre-treatment step, as well as ultrafiltration (UF) and nanofiltration (NF) membrane systems. The principal components (PCs) extracted in this approach were related to the major membrane foulant groups such as humic substances (HS), protein-like and colloidal/particulate matter in natural water. The PC score plots generated using the fluorescence EEMs obtained after just one hour of UF or NF operation could be related to high fouling events likely caused by elevated levels of colloidal/particulate-like material in the biofilter effluents. This fluorescence EEM-based PCA approach was sensitive enough to be used at low organic carbon levels present in NF permeate and has potential as an early detection method to identify high fouling events, allowing appropriate operational countermeasures to be taken. This fluorescence EEM-based PCA approach was also used to extract information relevant to reversible and irreversible membrane fouling behaviour in a bench-scale flat sheet cross flow UF process consisting of cycles of permeation and back-washing. PC score-based analysis revealed that colloidal/particulate matter mostly contributed to reversible fouling, while HS and protein-like matter were largely responsible for irreversible fouling. This method therefore has potential for monitoring modes of membrane fouling in drinking water treatment applications. The above approach was further improved by utilizing the evolution of the PC scores over the filtration time and relating these to membrane fouling by the use of PC scores??? balanced-based differential equations. Using these equations the proposed fluorescence-based modeling approach was capable of forecasting UF fouling behaviours with good accuracy based solely on fluorescence data obtained at time = 15 min from the initiation of the filtration process. In addition, this approach was tested experimentally as a basis for optimization by modifying the UF back-washing times with the objective of minimizing energy consumption and maximizing water production. Preliminary optimization results demonstrated the potential of this approach to reduce power consumption by significant percentages. This approach was also useful for identifying the fouling components of the NOM that were contributing to reversible and irreversible membrane fouling. Grand River water (Southwestern Ontario, Canada) was used as the natural water source for developing the techniques presented in this thesis. Future research focusing on testing these methods for monitoring of membrane fouling and treatment processes in large-scale drinking water treatment facilities that experience different sources of raw water would be useful for identifying the limitation of these techniques and areas for improvements.