Trent University

Heated leaf extracts of Euphorbia neriifolia (sweet aloes) are used traditionally in Guyana for asthma therapy, but the phytoconstituents have not been studied and phytohormones are generally unexplored in Euphorbia species. Phytoconstituents in asthma-effective traditional heated extracts were analyzed and compared with unheated leaves and latex extracts as screens to identify candidate compounds for asthma treatment. Analysis employed untargeted and targeted mass spectrometry-based metabolomics. The untargeted approach revealed thousands of features in samples with higher abundance in heated extracts and confirmation of 33 metabolite identities (confidence levels 2 and 3) which are known to have antioxidant and anti-inflammatory properties. Highly accumulated and unique features were detected in latex, and those characteristic compounds may reflect the expanded therapeutic uses of E. neriifolia globally. A targeted metabolomic analysis identified and quantified several cytokinins, including aromatic kinetin, and acidic phytohormones. Traditional heating improved the content of several cytokinins with known therapeutic potential, indicating they may be candidates for asthma management.

Author Keywords: asthma, cytokinins, Euphorbia neriifolia, metabolomics, sweet aloes, traditional remedies

Arturo Cruz Jr., born in 1953, was a highly influential and respected figure in Nicaraguan Politics. He was involved in the Contras. Cruz played a crucial role in supporting the Contras, helping to secure U.S. funding for the group which was a rebel group formed by the US against the Sandinista dictatorship in the 1980s. Later, he also served as the Nicaraguan ambassador to the US between 2007 and 2009. His involvement in the Contras was a controversial part of his career, but it did not define his contribution to Nicaraguan Politics. In this role, he worked tirelessly to influence American foreign policy towards his home country, which included advocating for democracy, human rights, and press freedom. Cruz's efforts to promote these values were a testament to his dedication to improving the lives of Nicaraguans. Cruz was deeply involved in various peace agreements in Central and Latin America, working towards resolving conflicts and promoting stability in the region. His contribution to the region went beyond Nicaragua, and he was well-respected for his efforts towards promoting peace and stability. Throughout his career, Cruz was a strong advocate for democracy and human rights. He believed that these values were essential for a country to prosper and develop. Cruz was a vocal advocate for press freedom and recognized the critical role of the media in promoting democracy and holding government officials accountable. This biographical study aims to explore the life and contributions of Arturo Cruz Jr. towards Nicaraguan Politics and the wider Latin American region. Through a detailed analysis of his life, this study seeks to shed light on an important

Migratory fish can influence the rivers where they spawn by depositing nutrients and organic matter which increase primary and secondary production. Past research in the Laurentian Great Lakes has focused on individual tributaries, accordingly, the spatial extent of subsidies and how environmental factors influence subsidies are not clear. To determine which tributaries received subsidies, I compared stable carbon isotope values (δ13C) of resident stream fishes above and below 54 barriers in 37 tributaries. Subsidies were found in found across 43 of the barriers. The subsidy magnitude varied among the lakes, with Lake Superior having significantly larger subsidies. Correspondence analysis of environmental factors showed that large differences in δ13C were associated with steeper river channels on the Canadian Shield with little agricultural land-use. Migratory fish supply resource subsidies to rivers across the Great Lakes basin, though their magnitude is contextually dependent.

Author Keywords: barriers, Great Lakes, migratory fish, resident stream fish, resource subsidies, stable isotopes

Mineral feedstocks, including alkaline mine wastes, can sequester CO2 as a dissolved phase (e.g., HCO3-) or a solid carbonate via enhanced rock weathering (ERW). For this thesis, the release of easily accessible Ca and Mg from non-carbonate sources was determined for kimberlite residues from several diamond mines and commonly proposed ERW rock types, including wollastonite and olivine. Batch leaches determined the CO2 sequestration potentials of kimberlites to be in the range of 3–12 kg CO2/t, which was exceeded by most ERW feedstocks. Leaches also assessed the release of Ni and Cr, elements of concern in ERW settings, and P and K, which benefit agricultural soils. Year-long leaching columns were deployed using kimberlite from the Gahcho Kué and Venetia diamond mines, wollastonite skarn, and olivine sand from the initial assessment. The kimberlite residues sequestered 0.03 kg CO2/t as dissolved inorganic carbon and 0.6 kg CO2/t as solid total inorganic carbon. Weathering of wollastonite skarn resulted in CO2 removal rates via mineral trapping of CO2 of 6.31 kg CO2/t, while the olivine sand yielded rates of 0.5 kg CO2/t via solubility trapping. Both methodologies used in this study demonstrated value in the prediction and monitoring of drainage chemistry as it relates to ERW and CO2 mineralization. Implementation of these strategies can progress ERW efforts by providing confidence in feedstock selection and the verification of carbon offsets.

Author Keywords: CO2 mineralization, Drainage chemistry, Enhanced weathering, Mine wastes, Mineral trapping, Solubility trapping

To examine comorbid pain sensitivity, temporal lobe epilepsy was modeled with a 42-stimulation amygdala kindling paradigm using rats. Sham and kindled rats' mechanical allodynia was not different before the formalin conditioned place aversion (FCPA) test. FCPA behaviour was not different, but twenty-four hours later kindled rats showed mechanical allodynia. Thermal sensitivity 48 hours after FCPA was not different. A second experiment revealed no difference in pre- and interictal mechanical and thermal sensitivity. Kindled rats did display a higher frequency of pain behaviours in the formalin nociceptive test, and greater early growth response 1 expression in the anterior cingulate cortex (ACC). The final experiment examined FCPA behaviour of sham and kindled rats given an ACC infusion of control (EGFP), or inhibitory designer receptor exclusively activated by designer drug (hM4Di). Kindled-EGFP rats did not spend a different amount of time in either compartment but Kindled-hM4Di rats spent more time in the formalin-paired compartment.

Author Keywords: Affective Pain, Amygdala Kindling, Emotion, Epilepsy, Pain

Mining and smelting degraded landscapes are characterised by heavily eroded soils that are acidic, contaminated with toxic metals, and depleted of essential nutrients. Regreening degraded landscapes has been proposed to support global carbon (C) mitigation measures and protect biodiversity. One of the world's largest regreening programs in the City of Greater Sudbury, Canada has been ongoing since 1978 and involves liming and fertilizing selected areas followed by planting primarily jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Ait.) trees. The main objective of this thesis was to improve our understanding of biogeochemistry in the City of Greater Sudbury regreened forests, and to determine how nutrient pools and cycling change as stands age. I established a chronosequence of forested sites between 15–40 years-old and to account for the effects of erosion, each site was categorized as "stable" (<10% bedrock cover) or "eroded" (>30% bedrock cover). Individual tree growth and nutrient accumulation in aboveground biomass (AGB) did not differ between stable and eroded sites and were comparable to rates reported from pine plantations in similar ecozones. Aboveground nitrogen (N) pools were six times larger than N applied in fertilizer, suggesting N limitation is most likely not a concern. Rates of C cycling were generally similar to those measured at unimpacted jack and red pine plantations. The exception being a decrease in mineral soil and aggregate C concentrations. However, at the ecosystem-scale the loss of soil C is trivial in comparison to increases in AGB C pools, leading to an overall increase in total ecosystem C following regreening (550,547 Mg in aboveground C across the 19,649 ha regreening landscape). Litter decomposition rates were higher at the regreening sites using a site-specific litter compared to a general common litter, indicating a home-field advantage for local decomposers. Soil temperature varied at the regreening sites and higher soil temperatures were related to higher rates of soil respiration. The regreening sites are rich in calcium (Ca) and magnesium (Mg); and while soils were generally poor in phosphorous (P) and potassium (K), foliar concentrations of P and K were comparable to those of "healthy" red pines. Overall, the regreening program appears to have increased tree growth and produced jack and red pine plantations that are biogeochemically similar to conifer plantations unimpacted by over a century of mining and smelting impacts.

Author Keywords: biogeochemistry, degraded landscape, forests, nutrient cycling, regreening, soil carbon

Ecological restoration of grassland ecosystems is increasing in scope in Ontario, as a result the demand for genetically appropriate, high-quality seeds of native plants is also increasing. This mixed methods study characterized fitness and seed quality traits using genetic, demographic and growth trial data for a keystone tallgrass prairie species Big bluestem (Andropogon gerardii). To estimate the ploidy levels in Big bluestem, our flow cytometric results indicated an average of 6.32 picograms of nuclear DNA within sixteen populations surveyed showing that hexaploid (6x) cytotypes are dominant in Southern and Central Ontario populations, aside from one 9x occurrence in Norfolk county, ON. Seed quality, measured through germination and viability testing did not change based on whether a population was remnant or restored. Concerningly, our study shows that remnant populations of Big bluestem are at risk of being lost as high quality seed sources likely because of the absence of stewardship and the resulting loss in population fitness. Workshops with prairie restoration practitioners suggest that there is significant vision behind the future of this work in the province, and that an ecosystem wide seed strategy for keystone tallgrass prairie species is a necessary next step to increase the sustainability of seed-based restoration strategies and preserve remnant site genetics.

Author Keywords: Big bluestem (Andropogon gerardii), Ecological Restoration, fitness, polyploidy, practitioner, seed quality

A significant portion (15-20%) of mercury (Hg) in the Arctic Ocean is believed to originate from Arctic rivers, such as the Mackenzie River watershed in the NWT. Recent (2005- 2020) Hg monitoring data of freshwater and fish tissue and environmental model outputs were compiled and used to develop a Bayesian Network Relative Risk model (BN-RRM), a probabilistic model capable of analyzing causal relationships. The objectives of the model were to estimate the risk posed to fish health and the subsequent dietary Hg-exposure to humans; to compare the relative risks between regions of the watershed; and to identify the influential Hg sources. The output of the BN-RRMs differed significantly throughout the watershed, with atmospheric Hg deposition and soil erosion Hg release consistently flagged as important explanatory variables. Analysis of the endpoint uncertainties revealed gaps in knowledge and in Hg datasets, which should be the focus of study for future monitoring programs.

Author Keywords: Aquatic Ecosystems, Arctic, Bayesian Network, Mercury, Risk Assessment, Toxicology

The seed oil of Carapa guianensis, known as Crabwood oil (CWO) and its fractionation was studied, focussing on chemical composition and physicochemical functionality. Compounds never reported before in CWO were identified, including limonoids such as Trichillin, ketostearic and hydroxyoleic acids. Yield of olein and stearin fractions correlated strongly with solvent polarity. Important bioactives were partitioned as a function of solvent polarity in the olein vs. stearin fractions. For example, up to 35% more of Gedunin were present in the liquid fractions. Solid fat content, crystallization and melting temperature and microstructure were significantly affected by fractionation and shown to be strongly correlated with solvent polarity. Fractionation was demonstrated to be a powerful tool to extend the physical functionality of CWO and concentrate its bioactives.

Author Keywords: Carapa guianensis, Chemical characteristics, Crabwood Oil, Dry and Solvent fractionation, Fractionation, Physical characteristics

Local environmental initiatives can create visible and essential changes and inspire greater environmental action. Municipal governments and local environmental non-governmental organizations (ENGOs) are important local actors, but their partnerships and relationships have not received much attention. This thesis examines what activities and relationships have been developed between municipal governments and ENGOs in the Peterborough region, what benefits they gain and what challenges they face during collaboration, and how these partnerships affect public perceptions of the organizations. I conducted 14 interviews with members of local ENGOs and municipalities and received 52 survey responses from residents. The findings indicate groups have unique relationships for planning, programming, and advocacy activities. Relationships were key and challenges included lack of time and prioritization, communication, and public buy-in. Partnerships provide an opportunity to share positive accomplishments and build reputation. This study sheds light on the complex relationships among local organizations and provides recommendations for improving partnerships.

Author Keywords: Community Engagement, Environmental Non-Governmental Organizations, Local Sustainability, Municipal Government, Partnerships, Relationships