Students

The Arctic contains huge quantities of soil carbon, yet most of this carbon is unavailable for microbial degradation because it is frozen in permafrost. Permafrost is thawing with increasing temperatures, and warming in the Arctic has now been confirmed to be twice the magnitude of global warming. If this soil carbon thaws and is mineralized, the impact on the climate system could be significant. However, little is known about variability in the quality of soil organic matter (SOM) across the landscape. Variation in SOM quality is an important link between permafrost thaw, global climate change, and other important environmental quality measures. SOM is both a source and sink of CO2 and CH4, which are major greenhouses. SOM quality can also impact the mobility and fate of contaminants, as well as nutrient transport within a watershed. Finally, SOM is capable of redistributing itself during permafrost disturbances, potentially stimulating soil degradation rates in affected areas and adding sediment to streams. Julianah is examining key factors that control variability in SOM quality and microbial community structure at a range of scales and how these might influences the decomposability of SOM and subsequent impacts on water quality.

Emily’s project is helping to develop a new method of detection and quantitation of microplastics in aquatic samples using fluorescence spectroscopy. Her role in this project is to set up models that will allow us to estimate the plastic-water binding coefficients for different compounds. In the lab, she tests the model predictions using preferred labelling candidates and observes the behaviours of microplastics moving through a system.

The Cornwall waterfront is contaminated with mercury and other legacy pollutants as a result of industrial activity over the last century. While industrial improvements and the closure of point-source polluters have decreased contaminant concentrations, sedimentary mercury remains at severely elevated levels. In aquatic environments, mercury can be converted to neurtoxic methylmercury and biomagnify through the food chain, causing impairments to ecological structure and function and impacts to human health. Effective mercury management relies on a comprehensive understanding of toxic ecosystem impacts, including long-term knowledge to understand baseline conditions, natural variability, and temporal history of contaminant impacts. Management also requires understanding how contaminants interact with other stressors to affect aquatic ecosystems. However, ecological monitoring in the Cornwall waterfront only began post-disturbance, and current toxicology tests do not consider environmental variability and other stressors. This study will employ a paleo-ecotoxicological framework to examine the influence of historic mercury and metal contamination on Cornwall waterfront ecology using chironomids as paleoindicators. The objectives are to assess the long-term ecological impacts of mercury and contaminant loading on chironomids from sediment cores and understand modern-day ecological impacts of mercury and other contaminants in the context of multiple stressors and environmental heterogeneity. 

There is a need to increase current capability of quantifying indicator organisms being monitored at wastewater treatment plants (WWTPs) in near real-time. Near real-time quantification of bacteria has the potential to improve WWTPs and watershed protection by allowing for the modification of treatment systems. This can prevent elevated pathogenic discharges and enable the use of naturalised treatment systems, which are highly effective for remote and rural communities. Better treatment control is made possible by rapid test results, completed before the residence time of the treatment or spread of pathogenic contamination. This project assessed test reliability with source water samples of high organic content, like that found in bogs, wetlands, and watersheds.  Developing an improved bacteria detection method advances the understanding of the watershed processes. Given that bacteriological composition is important for both discharge limits and determining the efficiency of water treatment within WWTPs, the project is looking to broaden bacterial quantifiability on a range of bacteria specific to wastewater quality. This research assesses the feasibility of quantifying wastewater E. coli and fecal coliforms composition, in comparison to reference methods, using rapid enzyme-substrate analysis with the wide-range of water quality found in wastewater and watersheds.

Understanding how our lakes respond to human stressors is critical to both fundamental biology and to enable evidence-based environmental policies. Oil spills are one such stressor but, while public concern over the environmental impacts of oil spills to ecosystems is growing, we still lack a complete understanding of how aquatic food webs will respond following spills, partially in freshwater. To address this gap, the BOREAL (Boreal lake Oil Release Experiment by Additions to Limnocorrals) project is working to give a comprehensive picture of the fate and effects of diluted bitumen (dilbit) on a natural food web in a temperate oligotrophic lake. We simulated dilbit spills in limnocorrals—large, 10-m diameter enclosures installed into a lake—at the IISD-Experimental lakes, monitoring both the short and long-term responses. Within this collaborative project, my research is focused on the lower food, assessing diluted bitumen’s effects on the structure and function of phytoplankton and microbial communities. Preliminary analysis suggests that diluted bitumen stimulated both phytoplankton and microbial communities with responses dependant on the spill size— a larger effect when more oil was spilled. We hope to provide useful algal bioindicators of oil pollution to track ecosystem recovery and determine the extent of microbial biodegradation of diluted bitumen in freshwater environments.

The design of waste stabilization ponds (WSP) can make use of four different types of models: Rules of thumb, Regression equations, First order kinetic models and Mechanistic models. Out of the four, only the last two are able to adapt to local climatic conditions and therefore produce the smallest variability in pond sizing estimates. The first order kinetic model can be used with a probabilistic approach to design which quantifies uncertainties in both the inputs and the model’s estimator to offer an associated uncertainty with the model’s output. A review of WSP design methods concluded that probabilistic designs offer a more accurate method of design by capturing local climate variability and should be further developed in the future. The only probabilistic WSP design method which appears in literature and makes use of first order kinetic models is the use of Monte Carlo Simulations. This approach requires a probability density function for the mean daily pond temperature (MDPT) which was identified as a critical variable in these types of simulations. In practice this variable can be estimated by using an empirical equation to get the mean monthly pond temperature and associating to it an uncertainty to capture daily variations (ex:+-10%) which produces a uniform distribution for the MDPT.  Alternatively, an appropriate transient heat flux model could be used to estimate a time series of daily mean pond temperatures from which statistical properties could be extracted. This second method would not only provide an a more accurate estimate for MDPTs but would also provide information regarding their autocorrelation. The autocorrelation between MDPTs is of importance in these simulations because retention times of these systems are longer than a day, meaning they require multiple MDPTs to be sampled per Monte Carlo iteration. 

Bacteria are detected by monitoring a fluorophore product from an indicator enzyme reaction where the enzyme should only be present in target bacteria (e.g. E.coli, fecal coliforms, or enterococci) in a test culture. Detection uses a polymer extraction step and a fibre-optic coupled fluorescence sensor. A matrix component like humic acid can interfere by inhibiting bacteria growth, by inhibiting the enzyme production of the fluorophore, or by affecting the extraction of the fluorophore into the polymer. The proposed research will entail controlled experiments isolating each of these steps to characterize the interference. We propose that signal reduction from interference with extraction can be used to estimate humic acid levels, and then to adjust for inhibition of growth to correct the results from the method. This will be tested with local surface water samples known to have various humic acid levels. 

In recent decades, with the expanding development of industry, large amounts of nitrogen-containing compounds (e.g. ammonium, nitrate) and organosulfur compounds (e.g. sulfolane) are being released into the environment. While processes are available for the ex-situ treatment of contaminated soils and groundwater, in situ treatment approaches such as bioremediation represents an effective, economical and less invasive alternative. For example, the Grand River discharging into the Canadian side of Lake Erie has presented elevated concentrations of NO3- and NH4+ and other nutrients; this is related to the agricultural activity and small Wastewater Treatment Plants in the watershed. The problems related to nitrogen-based compounds presence in soil and water are a concern and it is estimated that in Canada the site clean-up has a cost of $500,000 in five years and relies typically on mitigation of nitrate/nitrite byproducts rather than the ammonium source directly. Sulfolane due to its physical and chemical properties, has also been used as a solvent in a variety of applications. Sulfolane mobility in soil is very high but it does not interact significantly with soil organic matter or with the clay mineral portion of the soil, and is relatively inert; thus, it can not be retained on soil particles via sorption mechanisms, degradation seems to be the best option to reduce its presence in soil and water. While the bioremediation of NH4+ and sulfolane could be achieved in situ using individual treatment systems, a recommended approach would be an integrated bioremediation strategy. The importance of Nitrogen (added as NH4Cl and KNO3) and Phosphorus (added as KH2PO4 and K2HPO4) on sulfolane and diisopropanolamine degradation in soil sediments has been studied. NH4+ (and NO3-) present at a site could provide the Nitrogen source for sulfolane degradation and these could be co bioremediated at the site. The aim of the project is to: evaluate the integrated NH4+ (and NO3-) and Sulfolane bioremediation at bench-scale and investigate at mesocosm level the integrated biorremediaion of NH4+ (and NO3-) and Sulfolane under conditions previously established.

Cultural eutrophication, the excess input of nutrients by humans to waterbodies, is one of the biggest global threats to aquatic ecosystem health. The principal nutrients causing eutrophication are phosphorus (P) and nitrogen (N). Many human activities contribute N and P and effective management of eutrophication requires the identification of nutrient sources and their relative contributions to overall loading. This is difficult, because there can be several point and non-point sources in a single watershed. Thus, there is great interest in delineating relative sources of nutrients to improve management efforts. The first objective of this project is to test the effectiveness of novel stable isotopic tracers for identifying point and non-point sources of P and N. In this study, I will determine the relationship between nutrient inputs from non-point sources along a gradient of land use/land cover and δ18O-p, δ18O-n, and δ15N-n signatures in surface water to determine if these isotope tracers can predict anthropogenic sources of phosphate and nitrate. I will also determine the isotope signatures at known point sources to characterize these potential sources of N and P to the watershed. The second objective of this project is to establish a link between specific nutrient sources and harmful algal bloom (HAB) occurrence that will ultimately be used to inform the management of N and P inputs in the river. I will accomplish this objective by consolidating existing water quality data to understand spatial trends in nutrient dynamics and occurrence of HABs (measured as cyanobacterial toxins) within this watershed.

Wetlands are defined as areas of land that are flooded during part or all of the year, characterized by the development of plants that can grow in saturated soils. These ecosystems are among the most biologically productive; hosting a diverse number of wildlife and fauna. Wetlands are key in watershed management providing a transitional area between terrestrial and aquatic zones. In Canada, they account for 14% of the country's total land area and are known as "nature's kidney's" due to their innate capability to transform a wide range of pollutants into harmless by-products via their diverse microbial communities.

Engineered nanomaterials are increasingly used in a variety of industrial and consumer products, which, due to their abundance, creates a high probability for their introduction into a variety of ecosystems, at potentially harmful levels. Due to their antimicrobial properties, silver nanomaterials are one of the most frequently employed nanomaterials and, as such, are predicted to be released into the aquatic environment via treated wastewater effluent at concentrations which may cause potentially toxic effects. The wetland's microbial communities could be impaired by the release of these nanomaterials however the current research is limited. The objective of this project is to examine the effects of both pristine and weathered AG nanonmaterials through separate in-situ exposures in subsurface flow wetland mesocosms and examine the fate of Ag nanomaterials through destructive sampling of the wetland mesocosms.   

Matthew is focused on the applications of microalgae towards municipal wastewater remediation and biomass utilization. He is culturing monocultures and native polycultures of microalgae under different growth conditions to assess their ability to remove nutrients from wastewater while simultaneously producing viable by-products like biofuels precursors or nutritional supplements. Complementing this work, he is performing bench-scale experiments to screen different species for their ability to remove emerging contaminants (pharmaceuticals, personal care products, etc.) from Kingston, ON wastewater. In the future he hopes to study how microalgae can be used to remediate other forms of wastewater and use mixotrophic growth strategies to amplify the lipid yield of algal crops.   

If wastewater is not managed appropriately there are detrimental effects on the entire ecosystem. Wastewater is a complex mixture of human biological waste. When this complex mixture is improperly treated there is a potential high risk of toxins leaching into both drinking and recreational water in all water sources. Consequently, human health is negatively affected by the widespread increase in diseases and illnesses. Additionally, wastewater causes environmental degradation and inadvertently inflicts harm on the plant and animal biodiversity. An example of a water treatment system are Wastewater Stabilization Ponds (WSP). It is a significant and innovative approach in order to utilize natural decompositional wastewater treatment systems to breakdown and treat wastewater in an economically feasible way for small scale communities. A demand for WSP research is a critical reveal of the emerging climate changes which is a major stressor, particularly in small-scale communities. The goal of Lauren's work is to demonstrate the efficacy of wastewater stabilization ponds and to disseminate knowledge of this form of treatment for wastewater in this community and widespread throughout other communities. The intention is to demonstrate the efficacy of the water quality of WSP’s through numerical modelling and to build confidence in safeguarding human health and the environment from wastewater. Further research would need to be done to determine the effectiveness of WSP’s water quality parameters in other different climatic communities in Canada.   

Both the potent liver toxins microcystins (MC) and microplastics (MPs) are emerging environmental contaminants now recognized as being widely distributed across the globe. MCs are a diverse group of monocyclic heptapeptide hepatotoxins produced by several genera of freshwater cyanobacteria. MPs are defined as small particles of plastic less than 5 mm in diameter made from a variety of organic synthetic polymers. They may differ in product and polymer type, size, morphology, colour, and chemical additives. MPs are often categorized by primary and secondary sources. They may emerge from plastics intentionally manufactured to have a size less than 5 mm found in textiles, medicines, and personal care products and fragmentation and/or degradation of larger plastic objects, primarily from uncontrolled waste or litter. MPs may impact ecosystems by adhering to and/or being ingested by organisms, which may cause harmful physical effects. Additionally, MPs may be a source of hazardous chemicals via their additive ingredients and/or sorption of environmental contaminants. Recent studies have demonstrated the ability of MPs to act as a medium to concentrate hydrophobic (non-polar) organic contaminants in marine environments, driven by their characteristic surface hydrophobicity. This research has not been extended to MCs, which are relatively hydrophilic (polar) molecules implying that their affinity for MPs is negligible. However, many MC variants contain rare hydrophobic amino acid residues. Inherent in this lies the question: can MPs act as a medium to concentrate waterborne MC? If so, how does this alter the fate of MCs in freshwater ecosystems, and the toxic effects of MCs to freshwater organisms?

Groundwater is a vital source of drinking water globally, however most groundwater sources remain largely unregulated by the government. The lack if regulation and monitoring of groundwater leaves it susceptible to contamination. UN Sustainable Development Goal number 6 is to ensure access to clean water and sanitation for all. However, in order to improve water quality, water-related human health risks must first be identified and investigated. Bacterial contamination of groundwater may represent a hidden risk of antimicrobial resistance (AMR). AMR has been declared one of the top 10 threats to global health in 2019 by the World Health Organization. It is an ever-growing threat and the role of water as a source and dissemination route of antimicrobial resistant organisms (ARO) and antibiotic resistance genes (ARG) needs to be investigated. The objective of my research is to elucidate the potential roles of natural and anthropogenic drivers in AMR E. coli isolates from private well water sourced from wells in southeastern Ontario. 

Ontario has one of the largest groundwater-reliant populations in Canada, with approximately 1.6 million households utilising private wells. Unlike municipal drinking water systems, private drinking water wells are not required to meet the regulatory standards under the Ontario Safe Drinking Water Act (2002) and the Ontario Clean Water Act (2006) and well owners are the primary agents responsible for managing their drinking water. Well water testing, has previously been examined as an important indicator of stewardship behaviour. However, a previous Ontarian study found that just 11-12% of well owners complied with provincial water testing guidance (three tests per annum) during any year between 2008 and 2012 (Maier et al., 2014) suggesting  the presence of significant gaps in knowledge and/or tools for stewardship. In Canada, it is estimated that approximately 80,000 AGI cases per year were due to the presence of microbial pathogens in untreated private drinking water wells. Thus, it is critical to acknowledge the human-water system as coupled allowing for the integration of not only physical, but social pathways that can contribute to contamination. 

The social pathways and the extent to which a well owner’s knowledge, attitude and practices (KAP) contribute to the likelihood of contamination has yet to be appropriately addressed in exposure risk assessments for drinking water wells. The aim of my research is to identify and assess the gaps associated with current private well water stewardship; namely, KAP, in order to contribute to the development of a knowledge tool that will enable and support positive stewardship behaviours and ultimately minimize potential adverse health impacts. This project will focus on understanding and assessing water issues in two rural communities in southeastern Ontario by conducting community-based research methods including an online survey, focus groups, and semi-structured interviews.

Private groundwater sources supply drinking water to an estimated 1.5 million individuals in Ontario. Unlike public water supplies, private well water quality in Ontario is unregulated, with well owners responsible for testing, treating and maintaining their own drinking water sources. Domestic wells are susceptible to bacterial and chemical contamination due to a multitude including climate, improper land application/disposal of manure. As well as human mediated factors such as poorly located and/or malfunctioning septic systems, inappropriate land application/disposal of manure and an absence of water treatment. As a result, private drinking water systems serve as a potential source of waterborne pathogens, including shiga-toxin producing Escherichia coli (STEC). Given the potential for adverse human health effect such as acute gastrointestinal illness (AGI) it is pertinent to manage and maintain the integrity of private drinking water systems for sustainable water management by providing risk assessments (e.g. quantitative microbial risk assessment)that address the full scope of well water susceptibility and human illness. The overall aim of this study is to provide an accurate assessment of the human health burden associated with unregulated private drinking water in Ontario by examining the social and physical factors that influence community water security. This research project is a major component of a larger international collaborative project entitled The WELLness Project, that seeks to develop a risk assessment tool for private well owners and public health professionals.

My research focuses on recent changes to the structure of communities of algae and cyanobacteria on the St. Lawrence River. High nutrient loads emanating from local, agriculturally intensive watersheds have historically driven shifts to assemblages of algae in lakes and rivers worldwide. However, climate-change impacts are being increasingly recognised as important drivers of algal community structure, particularly favouring the growth of cyanobacteria in temperate lakes. Recent work suggests that there has been an increase in the relative abundance of cyanobacteria in the St. Lawrence River over the past 10-15 years, yet it remains unclear whether climate change, nutrients, or other local stressors such as legacy metal contamination are driving this assemblage shift. My project uses paleolimnological methods to disentangle these stressors; responses of algae and cyanobacteria to changes in their environments are preserved in aquatic sediments, which can be examined for changes to community assemblages over time through the analysis of dated sediment cores. Determining the roles of these different stressors in structuring algal community composition on the St. Lawrence River will help inform remediation efforts, and will enhance our understanding of climate-change impacts on large river ecosystems.

Emerging contaminants (EC) are compounds found in the environment that are growing as a source of possible concern due to increases in concentration, unknown impact to human/environmental health, and complexities surrounding their transport potential. As commercial manufacturers incorporate new materials into their products there exists the potential for the release of EC through mechanisms of use and weathering of the products. Current methods often analyze bulk concentrations of a species present in the commercial product with little focus on the mechanisms of release common in active use scenarios. Understanding the mechanism of release is important because these mechanisms are often responsible for transformations to the contaminant, altering its transport and toxicity potential. 

The emerging EC of concern for this project are silver nanoparticles. Ionic silver has been studied in the past for their release directly into the environment (from photographic waste) but the unique properties of nanoparticles and their incorporation into commercial products represents an area of concern due to potential for direct exposure to humans, release into the water cycle, and potential for transformation into other species. Silver nanoparticles have been found in common commercial products including clothing, food packaging, medical devices, sprays, and manufacturing materials and is often incorporated to inhibit bacterial growth. There currently exists no methodology to release and characterize silver nanomaterials being released from commercial products during active use scenarios. This research is to develop weathering methods capable of simulating physical and chemical conditions that silver-coated clothing undergo during their active use, which in turn will release silver nanomaterials characteristically similar to those released by human use. These released materials will then be examined the toxicity of these particles in wetland mesocosm systems.

Samira’s research aims to reduce fugitive dust emissions from tailings by cyanobacterial inoculation-based crust formation and MICP-derived crust formation methods. She will first investigate the formation of cyanobacterial crust in tailings by inoculation of two nitrogen-fixing species (Anabaena sp. and Nostoc muscorum). Following this she will evaluate MICP-assisted cyanobacterial crust formation by inoculating cyanobacteria in combination with essential substrates for biocement formation. The aim is to assess whether the proposed strategy can promote the formation of a more resistant crust to wind erosion. As cyanobacteria are photosynthetic organisms, crust formation is expected to be primarily within the uppermost millimeters of the surface layer (0-7 mm). For biostabilization of the subsurface layers of tailings, MICP via a denitrification pathway will be examined in the third phase of the study by using nitrate-reducing bacteria (Dechloromonas aromatica). Ultimately, the goal is to examine whether the inoculation of cyanobacteria on the tailings surface and nitrate-reducing bacteria in the subsurface layers will improve longevity and resistance to wind erosion of tailings material.

My research will be carried out on the Salmon River at Queen’s Kennedy Field Station. Land use near the river includes agriculture and residential cottages, which raises issues such as agricultural runoff and effluent from septic tanks. The reach of the stream that will be examined is a mixed primarily gravel-cobble stream, starting below the Laraby Rapids Dam. Gravel-cobble streams are common in areas that are moderately steep, as opposed to sand-bed streams with low gradients. These gravel-cobble beds are studied in laboratories extensively, however, in contrast to the case of sand streams, only a few isolated field studies aimed at understanding their hydrodynamics and sediment transport mechanics have been carried out to date. This research project is a great opportunity to considerably advance our understanding of such streams. The first part of this project will focus on the flow hydrodynamics and the coupling of flow to sediment transport and the second part will look at the growth and decay of biofilms within the stream. Biofilms are clusters of microorganisms that attach to non-biological surfaces, such as cobbles. They are important when considering the health of a stream because of their ability to recycle organic material and play a vital role in the ecosystem, however, their formation and fate are not completely understood.

The disposal and management of mine tailings remains a significant environmental challenge for the mining industry. Tailings can be subject to sulfide mineral oxidation, resulting in the formation of acidic, metal-rich drainage that can seep from tailings deposits and contaminate local waterways. Subaqueous storage has been commonly used to limit the formation of acid rock drainage (ARD) within a tailings deposit, however this requires a significant dedication of water resources and can cause geotechnical instability within the dams used for containment. The Victoria Junction Tailings Basin is a subaqueous tailings storage facility for a decommissioned coal mine in Cape Breton, Nova Scotia. The site represents a significant long-term liability, and it is in the interest of the agencies maintaining the site to determine a safe long-term storage solution that does not require the use of a water cover. Biogeocementation, or microbial-induced calcite precipitation (MICP) is a process by which microorganisms are able to facilitate the formation of calcium carbonate crystals by catalyzing the hydrolysis of urea. This process has several potential benefits with respect to environmental management. The objectives Sarah’s research is to assess the use of biogeocementation for the stabilization of coal tailings from the Victoria Junction Tailings Basin, determine the appropriate scale-up procedure for preparing bacteria and substrates, and determine the optimal method of distributing treatment solutions to the tailings.

Groundwater wells are the major source of drinking water for rural Canadians, including in Ontario. Previous studies have shown that these wells are susceptible to microbial contamination, putting public health at risk. My project will examine the impacts of various environmental and anthropogenic drivers on groundwater quality in the  context of both public and watershed health.  Unlike surface water, which flows through a region or area, groundwater persists 'locally' for extended periods and thus may serve as a better indicator of  overall watershed health for a given region.

In Ontario, private well waters are tested for both E. coli and total coliforms in order to provide some indication of water potability.  Using a dataset which combines microbial water quality data with well characteristic data (e.g. age, depth, construction, location, geology), the relationship of TC to E.coli, as well as to the various potential drivers of contamination, such as climate, well characteristics, land use, geology and other, will be explored.  My overall aims are to further define and better understand the role of TC as a microbial water quality indicator for water potability determinations, as well as determine what drives TC contamination and what this means in the context of overall watershed health.

The watershed of Lake Ontario is home to 10.1 million people and flows northeast into the St. Lawrence River, which is a a major transportation route for shipping, features a set of damns and lock systems, and is a changing complex ecosystem. As populations continue to grow and natural disturbance increases it is likely that human ad climate influences on the St. Lawrence River Watershed will change the landscape, if it already has not been. Water temperature is one of the most important factors influencing the biology and distribution of freshwater fish which are a central part of the rivers ecosystem. Land use change in watersheds is a common altering force, however change can come in various forms such as urban expansion, agriculture, forest harvesting, natural disturbances, hydrological alterations, and cumulative impacts. It is important to investigate the impact of these land alterations because they will not only effect the area around them but also the land surrounding them and whatever may lie downstream. By understanding changes in surface water temperature of the St. Lawrence River and how changes in water temperature can relate to land use changes, we can better understand the health of the ecosystem and future management of the watershed. My objective is to determine the St. Lawrence River's Watershed's overall health by using water temperature changes as an indicator of the impact of land use change or climate change, and how changing land use nearby crucial habitat impacts local biodiversity. 

My research focuses on the implications of agricultural run-off on amphibians. Retention ponds are becoming more frequently implemented in the agroecosystem as a means to attenuate the impacts of agricultural run-off directly entering surface waters. However, one of the consequences of using retention ponds is the attraction of wildlife to these constructed wetlands (e.g., as breeding grounds for amphibians). The main objective of this project is to investigate the effects of chronic exposure of the American toad (Anaxyrus (Bufo) americanus) to water from an agricultural retention pond. Preliminary results indicate that American toad tadpoles exposed to the pesticide mixture were significantly smaller and completed metamorphosis an average of 2 days earlier compared to control animals. These morphological and developmental disruptions corresponded to an alteration of hepatic gene expression of genes related to thyroid hormone signalling. This ongoing work will provide environmentally realistic information on the potential effects of agricultural activities and pesticide mixtures on a Canadian amphibian species. As well, it may provide insight on the efficacy and ecological impacts of retention ponds as mediators of agricultural releases.

Headwater streams can compose up to 80% of the total stream length within a watershed but remain most susceptible to stream burial during land-use change. Stream burial within agricultural landscapes involves rerouting streams into tile drains, culverts, and non-perforated pipes in order to increase crop production area and manage irrigation. Stream burial alters the stream’s physical, chemical and biological processes resulting from land-use change. My research models the impact of headwater stream burial within an agricultural landscape, to quantify the impacts of headwater stream burial at a subwatershed scale. I am using the Soil and Water Assessment Tool (SWAT) to model the impacts of headwater stream burial on downstream processes in the Kemptville Creek subwateshed of the Rideau River Watershed in Kemptville and surrounding area, Ontario, Canada. Results from this work will highlight the importance of headwater streams to subwatershed dynamics, including subwatershed hydrologic dynamics and biological productivity following headwater stream burial.

Arctic air temperatures are increasing at more than double the global rates with warming occurring predominantly in the winter months. Precipitation in the Arctic is expected to increase throughout the century causing enhanced snow deposition that can act as a soil insulator during the cold winter months. The combined effect of both these factors can influence soil microbial communities, biogeochemical cycles, and potentially surface water quality. Microbial activity during the winter can play a crucial role in ecosystem dynamics in the High Arctic. During the winter, fungal dominated microbial communities can access multiple mircosites through their mycelia and thereby mineralize greater amounts of nitrogen (N). This is a key process since Arctic ecosystems are N deficient which causes a limit to both vegetation and soil microbiome productivity during the growing season. Changes in the N cycle can also impact surface waters. Warmer winters can increase microbial productivity causing higher N mineralization rates, thereby, decrease N deficiency in the growing season which can trigger feedback mechanisms that could wither induce or dampen further warming. Baris' goal is to understand the effect of winter temperatures on nitrogen transformation rates in the Cape Bounty Arctic Watershed Observatory by conducting an incubation study using soil samples taken from a wet sedge tundra ecosystem.

Within Canada there is over 840,000 km of oil and gas pipelines which are critical to the Canadian economy, and whose failure can have significant economic and environmental impacts. It is essential to ensure the integrity of these systems. Many pipelines cross rivers, with river scour being a significant hazard for pipelines in Canada. This scour often results in the exposure of a buried pipeline, and if it leads to a free spanning pipeline, then this may fail due to fatigue caused by vortex induced vibration (VIV). At present there is a lack of procedures to assess the risk of VIV induced by river scour. Hudson’s project addresses this need and its primary objective is to develop physically based formulations to predict if the pipelines are at risk of becoming exposed and if VIV failure is likely to occur. The research involves novel laboratory experiments and numerical tests. The experiments will enable the observation of the process of exposure of buried pipelines, and constitute benchmark cases for the validation of FLOW-3D. The results will be used to develop an updated procedure for determining the depth of scour beneath a pipeline, ultimate free-span length and propagation rate for different flow conditions.