Understanding the spatial and temporal dynamics of catchment systems is crucial to understanding how hydrological behaviour may change over time and how this impacts on crucial aspects of catchment management such as flood generation, water resource management and the sources and fluxes of sediment, nutrients and contaminants. A combined statistical analysis was undertaken to assess whether similar catchment groupings respond to changing climatic drivers in the same way. A k-means cluster and PCA analysis grouped catchments in four clusters, which were differentiated by their topographical differences between lowland and upland catchments. Lowland catchments exhibited similar behaviours to changing trends of key hydroclimatic variables whereas more upland catchments showed diverse responses. We assessed the behaviour of 8 mesoscale catchments with increasing lowland areas for spatial and temporal runoff dynamics via the application of environmental tracers (stable isotopes and Gran alkalinity). Mean transit times were estimated using a lumped convolution integral model and lowland catchments with greater coverage of sedimentary bedrock exhibited longer turnover for water and solute fluxes. Tracer data was then implemented into a conceptual rainfall-runoff model to develop a model, which could represent both spatial and temporal dynamics rather than simply recreating the observed stream hydrograph. Finally, we assessed the role of dominant landscape characteristics (urban environments and grazing pastures) on the sources and fluxes of microbial contaminant risk to water quality. Catchments which had larger urban coverage and higher portion of grazing pastures yielded higher concentration fluxes of faecal coliforms which provided a first-order approximation of water quality risk at the catchment scale.

In Ghana, wastewater is frequently used as a source of irrigation water for crops in urban areas, due to water scarcity and an increasing population growth. The water contains high amounts of nutrients, but also other unwanted constituents such as heavy metals, pathogens and pharmaceutical residues and is a potential health risk for the consumers. This study aimed to determine the status of pharmaceutical pollution in irrigation water used in Chirapatre Estates, a suburb to Kumasi, Ghana. Chirapatre Estates is located on a hill sloping towards a stream, with a network of sewer lines connected to a Waste Stabilization Pond (WSP). Problems regarding disposal of pharmaceutical waste, frequently used medications in the area and water quality of irrigation water was analyzed through interviews and water analysis. The interviews were made with households, farmers and pharmacies and the water samples were collected at farms and the maturation pond, the final treatment in the WSP. The analysis focused on the water quality parameters; pH, Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), total phosphorus, phosphate, total nitrogen and nitrate. The empirical study showed high use of malaria treatment medication and paracetamol for adults as well as children. No instructions of disposal of unused medications were expressed through the pharmacy or by the government, causing the majority of the inhabitants to dispose their leftovers in the trash. One can speculate that there might be a possible risk of finding some pharmaceutical residues in the aquatic environment, especially for the types of pharmaceuticals that can be persistent. The results indicated that the water quality from the WSP and at the farming sites was acceptable when compared to the Ghana Environmental Protection Agency (EPA) guidelines, except for TSS and total phosphorus. Further treatment of the water is still suggested, since adjacent farms use the water frequently and the EPA guidelines are not fulfilled. Future studies are recommended to establish the pharmaceutical residues present in the stream water.

published_or_final_version / Chemistry / Master / Master of Philosophy

Cast iron pipes were installed broadly in North American water utilities. Many of these cast iron pipes are corroded and are continuous sources of Fe(II) ions in drinking water distribution systems. Recent studies have reported that soluble or particulate iron decreases water quality in distribution systems. In this study, an array of bench scale experiments were conducted to evaluate the impact of most common water parameters (e.g., pH, PO4, Cl2, and DOM) on the oxidation rate of Fe(II) ions, and on the formation of iron suspense in synthetic water samples. This was accomplished using a 24 full factorial design approach at a 95% confidence level. This study demonstrated that a lower content of iron suspension color, turbidity, and smaller particle size would appear to be obtained in presence of a phosphate based corrosion inhibitor at a pH value of 6.5 compared to a pH value of 8.5. To investigate the impact of Fe(II) ions, phosphate, pH and reaction time, and their interaction on DBPs formation in water samples, this study was conducted following an experimental design approach. Considering all the significant (α = 0.05, p < 0.05) factors, mathematical models for HAAs and THMs prediction were developed using 80 experiments. The models’ adequacy was checked thorough the statistical and graphical diagnostics. Different sources of natural water samples collected from three main water treatment plants in Halifax, Canada, were used to validate the models. This study suggested that the models’ performance were found to be excellent under a wide range of studied variables. Consequently, the most predominant iron oxides (goethite and magnetite) were used to investigate their impact on chlorine decay and DBPs formation study. Goethite and magnetite were also used for the adsorption of DBPs precursor (DOM). The DOM adsorption data illustrated to fit well with the Langmuir adsorption isotherm, indicating monolayer coverage. Molecular weight (MW) distributions of DBPs precursor (DOM) revealed that the higher molecular weight fractions adsorbed preferentially onto goethite followed by magnetite surface. The change of MW distribution of DOM was found to be in reasonable agreement with the change of DBPs formation in iron-water systems.

The focus of this study is the hydrochemical variability of runoff events in two nested alpine/sub-alpine basins. More specifically, the aim is to link hydrograph interpretations to results of hydrochemistry during rain storms in order to understand better short term hydrochemical fluxes and variability in solute sources. Hydrograph separation was undertaken by using four hydrological tracers; electrical conductivity, concentration of silica, and the stable environmental isotopes oxygen-18 and deuterium. The different methods predicted consistent high pre-storm water contribution for the lower station at peak flow (60%-90%) but less consistent results were found at the upper basin outlet (25%-90%). The chemical characteristics of the stream water have been analyzed using three different approaches, namely; statistical, mass balance, and thermodynamic. Linear correlation was used to investigate the statistical association between discharge and the individual chemical species. The mass balance approach was used to correlate stoichiometry of the bedrock mineralogy to dissolved constituents in the stream water. Finally, a thermodynamic technique was used to evaluate to what extent the stream water could be represented as an equilibrium system and how this changed over the course of the storm. The results from these methods showed that the stream water variability was caused almost entirely by dilution from rain water input.

Municipal Source Water Protection Plans (SWPPs) are instituted in efforts to maintain and protect water quantity and quality. An integral part of a SWPP is the Source Water Monitoring Plan (SWMP). Without well defined metrics it is impossible to determine if a SWPP is effective and meeting its general goals of maintaining water quantity and quality. A 16 month intensive monitoring plan was implemented to examine how a SWMP should be structured and how acquired data needs to be analyzed in order to answer specific water quality questions that may be posed. This thesis demonstrates the temporal and spatial variability of water quality data and discusses the utilization of common water quality metrics. The importance of developing goals for SWMP is stressed as, due to the range of information that can be acquired from different sampling strategies, SWMPs need to be tailored to meet the goals of a monitoring program.

This thesis summarizes the efforts of two years of field investigation and water quality data analysis. With a focus on construction sites, background monitoring was carried out at two sites and data from a third, active site was also included for analysis. The water quality data was used to estimate event-based sediment yield from each location, and continuously-collected rainfall, water level and turbidity data was used to calibrate an event-based hydrologic model (SEDCAD). Based on the results of this research and the outputs of the calibrated model, an event-based sediment yield equation calibrated for Southern Ontario conditions is presented in conjunction with an IDF design tool. The IDF design tool can be used to effectively size and site construction-phase erosion and sediment controls before shovels break ground. The regulatory framework by which such controls are assessed is also discussed, and improvements to existing stormwater management guidelines are proposed.

In a series of field and watershed scale studies, the genetic diversity of Escherichia coli in secondary habitats (e.g. soils and sediments) of an agricultural watershed was assessed in order to examine the dynamics of E. coli inhabiting these matrices and to determine their contribution to waterborne populations. Using replicated field plots, persistent subpopulations of E. coli were observed to be significantly affected by hillslope position due to inherent differences in soil texture and moisture content. The dynamics of E. coli populating tile drainage effluent in a working cultivated field were monitored and it was observed that putatively naturalized E. coli dominated the effluent after approximately 55 days following manure amendments. The contribution of tile drainage effluents to the waterborne E. coli population in an adjacent stream was exponentially related to tile discharge rates, regardless of whether the effluent was populated by manure-associated or naturalized E. coli strains. Streambed E. coli populations differed according to stream geomorphological features, with strains responding to sediment texture and water velocity distributions among the features. In a temporal study of sediment E. coli, population turnover was observed to be affected by sediment redistribution in highenergy stream reaches and was stabilized by immigration from adjacent catchment sources in low-energy stream reaches. Reach-specific connectivity between sediment and waterborne E. coli populations was observed in this watershed. Reach- and catchmentscale hyporheic processes are speculated to be occurring, which may be in part influenced by strain-dependent attachment behaviour of E. coli strains in disjoint stream reaches influenced by different catchment sources of E. coli. The attachment of waterborne E. coli to suspended particles was observed to be associated with land use, water quality and suspended particle variables. The relationship of land use type to particle attachment reinforces the hypothesis that strain-specificity in attachment behaviour can affect the transport of E. coli in fluvial systems. This work provides evidence that putatively naturalized strains in cultivated fields can contribute a large part to waterborne E. coli, and that reach-specific hydrological factors need to be considered when relating sediment- to waterborne E. coli in fluvial systems.

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No description available.