Historical lead in tap water data from the City of London and the City of Ottawa were examined for trends and correlations over time. Factors such as the sampling protocol, temperature, and pH were analyzed to determine their specific impacts on lead. Linear and logistic regression models were also developed to predict lead concentrations in tap water based on different water quality parameters. Finally, a physical mass transfer and flow model (zonal model) was validated with the lead data from the two municipalities. Results indicate the potential use of the regression and zonal models to predict a range of lead concentrations for a number of homes in a Canadian city based on the field data. These methods may allow municipalities to determine the impact of a corrosion control strategy such as a pH increase without having to sample for lead in people's homes.

Historical lead in tap water data from the City of London and the City of Ottawa were examined for trends and correlations over time. Factors such as the sampling protocol, temperature, and pH were analyzed to determine their specific impacts on lead. Linear and logistic regression models were also developed to predict lead concentrations in tap water based on different water quality parameters. Finally, a physical mass transfer and flow model (zonal model) was validated with the lead data from the two municipalities. Results indicate the potential use of the regression and zonal models to predict a range of lead concentrations for a number of homes in a Canadian city based on the field data. These methods may allow municipalities to determine the impact of a corrosion control strategy such as a pH increase without having to sample for lead in people's homes.

Bioaugmentation with Dehalococcoides-containing cultures is a successful technology for the remediation of chlorinated ethene-contaminated roundwater. The overall goal of this research was to identify and characterize genes that are used by a Dehalococcoides-containing culture, KB-1, during degradation of Trichloroethene (TCE) to ethene, via cis-Dichloroethene (cDCE) and vinyl chloride. Firstly, the diversity and dynamics of the microbial populations within KB1 was assessed using 16S rRNA clone libraries and quantitative PCR analyses. Secondly, reductive-dehalogenase-homologous- (RDH) genes in KB1 were identified, sequenced and their transcription compared through RNA-generated RDH cDNA clone libraries. Finally, to elucidate functionally important genes within the community, Shotgun metagenome microarrays were constructed and used to investigate transcription during dechlorination. Results of the phylogenetic analyses indicated that KB1 is a diverse community of microorganisms whose stability is enhanced by functional redundancy within the culture. To fully understand this diverse community of uncultivated microorganisms a metatranscriptome approach was used. Experiments with shotgun metagenome microarrays identified spots which were statistically significantly differentially expressed during dechlorination. These spots were then sequenced, revealing Dehalococcoides and non-Dehalococcoides-genes which are important during dechlorination. These results demonstrated that shotgun microarrays can be constructed without prior sequence knowledge and used to effectively examine differential transcription within an uncultivated community. Subsequently, all of the spots of the array were sequenced, and additional array experiments were conducted. Sequencing identified 24 reductive dehalogenase genes in the culture, and analysis of the microarray results indicated that many of these RDH genes were differentially expressed in response to certain chlorinated compounds. Interspecies interactions were also highlighted as results suggested that non- Dehalococcoides microorganisms provide partial corrinoids which Dehalococcoides salvages to synthesize cobalamin which is essential for reductive dehalogenation. Transcription of CRISPR-associated genes also indicated interaction between phage and other microorganism in the KB1 community. Overall these results provided sequence and transcription information about possible biomarkers for reductive dechlorination by KB1 and can be used for more effective design and monitoring of bioremediation technologies.

Thermal remediation is an efficient and cost effective method for the removal of organic compounds from the subsurface. However, complete removal of these compounds cannot be achieved by this technology alone. It is generally assumed that bioremediation will provide the polishing steps at thermally treated sites. In this study, soil was collected from a hydrocarbon contaminated site that previously underwent thermal remediation. A microcosm batch study was conducted to determine the impacts of thermal remediation on indigenous microorganisms and their ability to degrade naphthalene. Soils that reached varying peak temperatures were set up in microcosms at temperatures experienced along their respective cooling profiles. Naphthalene degradation was not detected within any of the unamended microcosms within a 6 month time frame, although, archaea growth was detected in the microcosms after 2 months of acclimation, accompanied by iron reduction and significant methane production assumed to have arisen from degradation of methanol.

This thesis examined the influence of relative permeability, constant concentration contaminant sources, multi-component gases, and latent heat effects on electrical resistance heating (ERH). An existing electro-thermal model coupled to a macroscopic invasion percolation model (ETM-MIP) was modified for the study. Simulations results showed that ERH may generate enough gas to significantly reduce aqueous phase relative permeability, thereby significantly reducing aqueous phase velocity and mass transport. When a constant concentration source zone is simulated, gas generation persists and gas bubbles travel much further with greater redistribution of contaminant. By including dissolved nitrogen and oxygen as background components, multi-component partitioning increases, resulting in more gas bubble generation. Finally, by taking into account latent heat, the model is able to simulate energy associated with vaporization, and constant co-boiling temperature plateaus are predicted in contaminant source zones.

Thermal remediation is an efficient and cost effective method for the removal of organic compounds from the subsurface. However, complete removal of these compounds cannot be achieved by this technology alone. It is generally assumed that bioremediation will provide the polishing steps at thermally treated sites. In this study, soil was collected from a hydrocarbon contaminated site that previously underwent thermal remediation. A microcosm batch study was conducted to determine the impacts of thermal remediation on indigenous microorganisms and their ability to degrade naphthalene. Soils that reached varying peak temperatures were set up in microcosms at temperatures experienced along their respective cooling profiles. Naphthalene degradation was not detected within any of the unamended microcosms within a 6 month time frame, although, archaea growth was detected in the microcosms after 2 months of acclimation, accompanied by iron reduction and significant methane production assumed to have arisen from degradation of methanol.

This thesis examined the influence of relative permeability, constant concentration contaminant sources, multi-component gases, and latent heat effects on electrical resistance heating (ERH). An existing electro-thermal model coupled to a macroscopic invasion percolation model (ETM-MIP) was modified for the study. Simulations results showed that ERH may generate enough gas to significantly reduce aqueous phase relative permeability, thereby significantly reducing aqueous phase velocity and mass transport. When a constant concentration source zone is simulated, gas generation persists and gas bubbles travel much further with greater redistribution of contaminant. By including dissolved nitrogen and oxygen as background components, multi-component partitioning increases, resulting in more gas bubble generation. Finally, by taking into account latent heat, the model is able to simulate energy associated with vaporization, and constant co-boiling temperature plateaus are predicted in contaminant source zones.

Fresh and aged iron particle attachment onto model mineral surfaces was studied using atomic force microscopy based – force spectroscopy (AFM) in different water chemistries as well as in the presence of surface modifiers for the particles (carboxymethyl cellulose polymer). The forces of interactions measured with AFM were explained in terms of classical DLVO forces (electrostatic, Born and van der Waals forces) as well as hydration, steric and magnetic forces, which are not accounted for by classical models. Theoretical interpretation of the results was thus performed using extended models, in which such interactions were considered. In the absence of surface modifiers, iron particle attachment onto silicates and iron oxides appeared favorable in pure water and salt solutions at pH 4 and 5.5, but was hindered in water amended with humic acids. Attachment of bare CIP was also unfavourable at pH 8, except in the presence of CaCl2 salt at 100 mM concentrations. Attachment between iron particles and iron oxides was favorable even in the presence of polymeric coatings. Conversely, in all solutions such coatings contributed to electro-steric repulsion between particles and silicates, which dominated over attractive van der Waals forces, albeit to a lesser extent in the presence of salts. To best assess the role of polymeric coatings in particle attachment, polymer sorption onto the model mineral surfaces considered was investigated using a Quartz Crystal Microbalance with Dissipation Monitoring. The results obtained confirmed the AFM findings, and furnished insights regarding the role of salts on polymer sorption onto substrates. Finally, the effect of aging on attachment was probed both by AFM and by analyzing cementation phenomena of iron aggregates using scanning electron microscopy, as well as by probing changes in particle compositional properties with various spectroscopy tools. The major effect of aging was to promote the formation of large cemented aggregates, which did not appear prone to disruption or remobilization.

Fresh and aged iron particle attachment onto model mineral surfaces was studied using atomic force microscopy based – force spectroscopy (AFM) in different water chemistries as well as in the presence of surface modifiers for the particles (carboxymethyl cellulose polymer). The forces of interactions measured with AFM were explained in terms of classical DLVO forces (electrostatic, Born and van der Waals forces) as well as hydration, steric and magnetic forces, which are not accounted for by classical models. Theoretical interpretation of the results was thus performed using extended models, in which such interactions were considered. In the absence of surface modifiers, iron particle attachment onto silicates and iron oxides appeared favorable in pure water and salt solutions at pH 4 and 5.5, but was hindered in water amended with humic acids. Attachment of bare CIP was also unfavourable at pH 8, except in the presence of CaCl2 salt at 100 mM concentrations. Attachment between iron particles and iron oxides was favorable even in the presence of polymeric coatings. Conversely, in all solutions such coatings contributed to electro-steric repulsion between particles and silicates, which dominated over attractive van der Waals forces, albeit to a lesser extent in the presence of salts. To best assess the role of polymeric coatings in particle attachment, polymer sorption onto the model mineral surfaces considered was investigated using a Quartz Crystal Microbalance with Dissipation Monitoring. The results obtained confirmed the AFM findings, and furnished insights regarding the role of salts on polymer sorption onto substrates. Finally, the effect of aging on attachment was probed both by AFM and by analyzing cementation phenomena of iron aggregates using scanning electron microscopy, as well as by probing changes in particle compositional properties with various spectroscopy tools. The major effect of aging was to promote the formation of large cemented aggregates, which did not appear prone to disruption or remobilization.

Bioaugmentation with Dehalococcoides-containing cultures is a successful technology for the remediation of chlorinated ethene-contaminated roundwater. The overall goal of this research was to identify and characterize genes that are used by a Dehalococcoides-containing culture, KB-1, during degradation of Trichloroethene (TCE) to ethene, via cis-Dichloroethene (cDCE) and vinyl chloride. Firstly, the diversity and dynamics of the microbial populations within KB1 was assessed using 16S rRNA clone libraries and quantitative PCR analyses. Secondly, reductive-dehalogenase-homologous- (RDH) genes in KB1 were identified, sequenced and their transcription compared through RNA-generated RDH cDNA clone libraries. Finally, to elucidate functionally important genes within the community, Shotgun metagenome microarrays were constructed and used to investigate transcription during dechlorination. Results of the phylogenetic analyses indicated that KB1 is a diverse community of microorganisms whose stability is enhanced by functional redundancy within the culture. To fully understand this diverse community of uncultivated microorganisms a metatranscriptome approach was used. Experiments with shotgun metagenome microarrays identified spots which were statistically significantly differentially expressed during dechlorination. These spots were then sequenced, revealing Dehalococcoides and non-Dehalococcoides-genes which are important during dechlorination. These results demonstrated that shotgun microarrays can be constructed without prior sequence knowledge and used to effectively examine differential transcription within an uncultivated community. Subsequently, all of the spots of the array were sequenced, and additional array experiments were conducted. Sequencing identified 24 reductive dehalogenase genes in the culture, and analysis of the microarray results indicated that many of these RDH genes were differentially expressed in response to certain chlorinated compounds. Interspecies interactions were also highlighted as results suggested that non- Dehalococcoides microorganisms provide partial corrinoids which Dehalococcoides salvages to synthesize cobalamin which is essential for reductive dehalogenation. Transcription of CRISPR-associated genes also indicated interaction between phage and other microorganism in the KB1 community. Overall these results provided sequence and transcription information about possible biomarkers for reductive dechlorination by KB1 and can be used for more effective design and monitoring of bioremediation technologies.