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INTEGRATED SYNCHROTRON APPROACHES TO CHARACTERISE ORGANIC MATTER-IRON PHASES RELEVANT TO PASSIVE MINE WASTE REMEDIATION SYSTEMS
No full textThe work presented in this thesis used synchrotron X-ray scattering and X-ray absorption spectroscopy (XAS) techniques to characterize samples relevant to mine waste systems. Passive remediation systems such as permeable reactive barriers and constructed wetlands aim for long-term contaminant immobilization. Contaminant removal is achieved through mechanisms such as precipitation in sulfide phases and/or sorption onto iron oxyhydroxides. These processes occur in the presence of various dissolved organic compounds such as tannins that are released in natural environments through organic matter degradation. Research on tannin influences on mineral precipitation is necessary to better understand contaminant immobilization processes. This thesis aims to examine the role tannins (using tannic acid as the model compound) play during iron oxyhydroxide and iron sulfide precipitation. Tannic acid was found to favour formation of crystalline phases when present during ferrihydrite and mackinawite precipitation. The presence of tannic acid during ferrihydrite synthesis favoured the formation of lepidocrocite and goethite as tannic acid concentration increased. The presence of tannic acid during mackinawite synthesis favoured formation of greigite, however increasing tannic acid concentration also led to ferrihydrite precipitation . Tannic acid is redox sensitive and in the presence of redox sensitive metals such as Fe, it can change the system’s chemistry. During ferrihydrite synthesis, tannic acid reduced Fe(III) to Fe(II) even under aerobic conditions. The tannic-acid generated Fe(II) might have catalyzed the transformation of early formed ferrihydrite to lepidocrocite and goethite or they might have formed through oxidation of the produced Fe(II). During mackinawite synthesis, tannic acid catalyzed oxidation of Fe(II) to Fe(III) and S(-II) and S0; changing the system’s chemical conditions to favour greigite and ferrihydrite precipitation. This project suggests that the presence of tannic acid as well other redox sensitive tannin compounds may be important in passive remediation systems since they influence redox conditions and promote the formation of a mixture of crystalline and poorly crystalline phases at initial stages of iron oxyhydroxide and iron sulfide precipitation
ECONOMIC EVALUATION OF SELECTED POLICIES TO ENCOURAGE ADOPTION OF FIELD SHELTERBELTS IN SASKATCHEWAN
No full textHistorically, farmers on the Canadian Prairies have planted field shelterbelts on their farms to reduce the damage done by wind erosion due to extreme climatic conditions. However, incidence of such damages has been reduced with improvements in agricultural production methods and cultural practices (such as zero-till, and reduced summer fallowing, among others). Some farmers now regard these field shelterbelts as an economic nuisance. Although many of the barriers to the adoption and retention of shelterbelts by farmers are mostly related to their economic costs, a poor understanding of their environmental benefits may also have played an important role.
In response to the future changing climate, reducing greenhouse gas emissions has become a major objective of various national governments, including the Canadian government. Shelterbelts can play an important role in mitigating greenhouse gases through sequestration of carbon. This requires farmers to plant more shelterbelts. To this effect, an understanding of the factors that influence farmers’ decision regarding field shelterbelt adoption, as well as measures to encourage their adoption to increase the environmental benefits of field shelterbelts is relevant. Using a combination of a binary logistic regression model, combined with a spreadsheet-based farm-level net revenue simulation model and other numerical estimation approaches, in this study, the factors that may influence farmers’ decisions to adopt field shelterbelts were empirically estimated. In addition, the study estimated the potential impacts of selected policy instruments in encouraging the adoption of field shelterbelts in Saskatchewan. For this purpose, two policy instruments were selected – distribution of free shelterbelt seedlings to farmers, and negative carbon tax for carbon sequestration through shelterbelts. The value of negative carbon tax was determined by the price of carbon. This study considered four different carbon price scenarios – 110.49/tCO2(eq), 10/tCO2(eq) in 2018, with 15/tCO2(eq) yearly increment from 2023 to 2030). The two selected policy instruments were evaluated based on four policy evaluation criteria; (1) Farm-level net revenue, (2) Probability of increasing field shelterbelt adoption, (3) Amount of carbon sequestered, and (4) Fiscal cost per tonne of carbon sequestration.
The study results indicated that factors such as farmers’ education level, farm income, and their perceptions about the environmental benefits of field shelterbelts had a positive and significant effect on farmers’ decisions to adopt field shelterbelts. Moreover, between the two selected policy instruments, results showed that the negative carbon tax policy instrument performed better based on most of the policy evaluation criteria (3 out of 4 – impact on farm-level net revenue, probability of increasing field shelterbelt adoption, and total amount of carbon sequestered) in all the soil zones of Saskatchewan. Among the four different rates of the negative carbon tax (only on the carbon sequestered through shelterbelts), study results indicated that negative carbon tax set at a carbon price of $ 574.13/tCO2(eq) was the more effective policy instrument in encouraging the adoption of field shelterbelts in Saskatchewan since it provided the higher rate of adoption than the distribution of free seedlings to farmers. The study’s findings suggest that policy designed to increase the adoption of field shelterbelts should clearly define the policymaker’s objective of whether to maximize policy benefits or minimize policy costs since the choice of an appropriate policy or set of policies may differ under these policy objectives. Particularly, it is recommended that providing free shelterbelt seedlings should be considered if the objective of the policy design is to minimize policy costs, while the negative carbon tax instrument could be considered if the objective of the policy design is to maximize the potential benefits of the policy. In general, the study’s findings suggest that governments’ policy intervention to encourage adoption of field shelterbelts by farmers in Saskatchewan through financial rewards can encourage farmers to plant and maintain field shelterbelts on their farms
Level Up: Supporting In-Game Skill Development
Get PDFVideo games are challenging and complex. They require players to master a diverse set of skills to succeed. Through play, players acquire and eventually master these skills, transitioning from novice to expert through skill development. Making progress and performing well in a game is directly tied to a player's ability to master in-game skills, so players are strongly motivated to get better at the games they play. Games can do a good job of supporting a new player's learning, but too often they leave a player to work out for themselves how to improve and get better at the game. The problem is that game designers do not always know how to support skill development in their games. To solve this problem, we need to better understand how skill learning occurs in games, as well as explore specific new approaches for supporting skill learning in games. Games are not the only context in which skill development and high performance is important --- the field of human performance already explores this in detail and provides many theories to apply to this new domain. Inspired by these theories I explore different ways of supporting players’ learning at two different stages of skill development. First, I explore how early learning can be supported through the use of guidance and explore how later learning can be supported by modifying practice. Testing out the effects of guidance by providing new players with different levels of navigation guidance and evaluating how well they were able to learn the environment, I found that guidance improved a player's immediate performance and allowed them to complete tasks within the game more effectively. I evaluated the idea of modifying practice by applying spaced practice (having players take breaks when playing) in two different games, as well as by adding checkpoints to a side-scrolling platform game. I found that having players take breaks improved players' immediate performance and allowed them to make more progress within the game and that a variety of break lengths were effective. I found that checkpoints allowed players to make progress in the game and learn the game just as effectively as when checkpoints were not present. Overall, this research adds to our understanding of how skill development occurs in games and provides some concrete examples of how support methods used in other contexts (such as in sports) can be applied to digital gaming
Nobody’s job : attending the birth of a new small- scale water tool for the Prairies
Get PDFCanada First Research Excellence Fund, CFREF 2015-00010First person account of interactions involved in developing a hydrological planning tool to support small infrastructure planning in the Canadian prairie region
Development, Evaluation, and Implementation of a Standardized Fish Community-Based Index of Biotic Integrity for Evaluating the Ecological Health of Boreal Plains Streams and Rivers in Saskatchewan, Canada
Get PDFFreshwater ecosystems face increasing threats from anthropogenic influences and multiple stressors, necessitating effective management techniques to assess, conserve, and restore aquatic health. Fish-based Index of Biotic Integrity (IBI) tools play a crucial role in assessing and monitoring the health of freshwater ecosystems. Despite a prosperous, significant fishery and ample aquatic habitats, Saskatchewan (SK), and much of Canada’s boreal region, currently lack a fish-based IBI framework, and the development and evaluation of such a tool could complement existing monitoring programs and provide a novel approach to fisheries and aquatic resource management within SK, and more broadly, northern Canada. This study developed and evaluated a fish-based IBI framework for streams and rivers of the Beaver River watershed in the Boreal Plain ecozone of SK. This watershed exhibits a gradient of human disturbance, ranging from agriculture in the south to relatively unimpacted forest landscapes in the north, making it an ideal location to study the potential effects of human stressors on fish and aquatic ecosystems and evaluate the IBI in a relatively homogenous area with multiple land-use stressors.
By assessing various measures of land use and fish habitat, I classified minimally disturbed (or low-stress) conditions, established a gradient of stream and river health throughout the Beaver River watershed at 18 sites, and then determined fish community response to known stressors. A potential limitation of fish-biomonitoring studies is the effect of seasonality and timing of sampling on the interpretation of results, especially in northern regions where temperature extremes likely influence fish reproduction and mobility. Therefore, I revisited five of the sites annually over a three-year period to test the sensitivity of the IBI to interannual variability. I identified nine metrics, selected across the major metric categories, that showed the highest responsiveness to human disturbance. As expected, IBI scores decreased with increasing stress, but a depauperate and tolerant fish community, confounded by high interannual variability in environmental conditions and the fish community, created difficulties in developing the IBI and limited my ability to attribute variations to natural trends through time or anthropogenic influence. My results reinforce the importance of long-term monitoring to decipher trends in natural variation of fish communities from variation created by anthropological stressors and can inform fisheries and aquatic ecosystem health management and decision making in SK as well as other Boreal Plains’ watersheds throughout Canada
The Virtual Water Gallery: Changing Attitudes through Art
Get PDFEGU23-8658, updated on 26 Feb 2023
https://doi.org/10.5194/egusphere-egu23-8658
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under the Creative Commons Attribution 4.0 License.Peer ReviewedWater is life. Water-related challenges, such as droughts, floods, wildfires, water quality degradation, permafrost thaw and glacier melt, exacerbated by climate change, affect everyone. Yet, it is challenging to communicate science on difficult, highly volatile topics such as water and climate change. Conceptualizing water-related environmental and social issues in novel ways, with engagement between diverse audiences may lead to comprehensive solutions to these complex challenges. Art can be a catalyst in the co-creation of new knowledge for the benefit of society.
The Virtual Water Gallery (VWG) is a transdisciplinary science and art project of the Global Water Futures (GWF) program. Launched in 2020, the VWG aims to provide a collaborative space for dialogues between water experts, artists, and the wider public, to explore water challenges. As part of this project, 13 artists representing women’s, men’s and Indigenous voices across Canada were paired with teams of GWF scientists to co-explore specific water challenges in various Canadian ecoregions and communities. These collaborations led to the co-creation of artworks exhibited online on the VWG (www.virtualwatergallery.ca) in 2021.
The VWG recently came to life in 2022 with an in-person exhibition in Canmore, Alberta, Canada. Surveys were developed to capture changes in perspectives regarding climate change and water challenges through this art-science exhibit. Participants of the VWG (artists and scientists), visitors to the online gallery, and visitors to the in-person exhibition in Canmore were all invited to take part in those surveys. The preliminary results from the surveys suggest that participants experienced changes in behaviour regarding water-related climate change mitigation, and that the degree of change depends on factors such as age, income and lived experience (i.e., floods and droughts). The results help elucidate how art viewers engage with art based on science and how science messages can be more effectively communicated through art
Repeatability of Ovarian Antral Follicular Wave Dynamics during the Human Menstrual Cycle
Get PDFContext: Ovarian follicles are fluid-filled sacs which contain oocytes (‘egg’ cells). The number of ovarian follicles depletes with age and thus, is indicative of reproductive potential. Two or three waves of follicular development have been identified in the human menstrual cycle, consistent with domestic farm animals. In the bovine species, the number of follicular waves has been documented to be repeatable in 70% of estrous cycles. However, repeatability of the numbers and patterns of follicular waves have not been evaluated in humans.
Overall Objective: To test the hypotheses that the numbers and patterns of follicular waves are repeatable across multiple menstrual cycles.
Materials and Methods: Transvaginal ultrasonography (TVUS) was conducted every 1-3 days over 2 Inter Ovulatory Intervals (IOIs) for 22 ovulatory participants. Participants of reproductive age (RA, age 18-35, n=14) and advanced reproductive age (ARA, age 36-55, n=8) were evaluated. The number of follicles on each day across the IOI were tabulated for the following diameter categories: 2-5 mm, 2-10 mm, ≥5 mm, ≥4 mm and 4-6 mm. The size and location of follicles ≥4 mm within each ovary were sketched each day during the IOI. The growth profiles of individually identified follicles that attained a diameter of ≥6 mm were retrospectively determined and graphed. A wave was defined as an increase and subsequent decrease in the number of follicles ≥5 mm, associated with the growth of 1 or more follicles to ≥6 mm.
Results: Across 2 IOIs, the mean number of waves was 2.1 for both the RA and ARA groups (p=0.16). In the RA group, 27/28 (96%) of cycles were comprised of 2 waves while 1/28 (4%) had 3 waves. Similarly, 15/16 (94%) of cycles in ARA participants had 2 waves while only 1/16 (6%) had 3 waves. The patterns of waves documented included 1) minor-major, 2) major-major, 3) major- minor-major and 4) minor-minor-major. The majority of RA (21/28; 75%) and ARA (12/16; 75%) participants developed a minor-major pattern of development. Furthermore, 6/28 (21%) and 3/16 (19%) of cycles from the RA and ARA groups, respectively revealed a major-major pattern. One RA participant (1/28; 4%) demonstrated a major-minor-major pattern, and one ARA participant (1/16; 6%) demonstrated a minor-minor-major pattern. The number of waves (2 or 3) across 2 IOIs was repeatable in 20/22 (91%) of participants. Similarly, the pattern of waves across 2 IOIs was repeatable in 13/22 (59%) of participants. No differences in the numbers or patterns of waves were detected among age groups nor continuous versus discontinuous cycles (p>0.1).
Conclusions: The numbers and patterns of ovarian follicular wave dynamics were repeatable across 2 cycles in the majority of participants. Elucidating the repeatability of antral follicular wave dynamics may enable the individualization of hormonal contraceptive and ovarian stimulation protocols
Global Water Futures (GWF) holds Its Final Annual Open Science Meeting, announces an Extension to 2025 and launches the Global Water Futures Observatories Project
Get PDFNewsletter articleCanada First Research Excellence FundNon-Peer Reviewe
Self-Supervised Learning for Semantic Segmentation of Images
Get PDFArtificial Neural Networks (ANN) are powerful Machine Learning (ML) models that can help solve problems that are hard or even impossible to design solutions for by hand. These models learn to exploit
information present in their target datasets to solve various problems. However, labelling data can be quite
expensive, time-consuming and often requires a domain expert. Therefore it would be quite beneficial if one
could train a model in such a way that exploits unlabeled data. Fortunately, Self-Supervised Learning (SSL)
methods are a family of learning algorithms that attempt to do just that. Many SSL methods exist, but in
this thesis, we explore Barlow Twins (BT) — a siamese network based on redundancy reduction, and Image
Reconstruction (IR) — a method proposed in Karnam’s thesis. In addition, we extend the Image Reconstruction method with both Coarse Cutout and Hide-and-Seek augmentations as they have been applied in similar
supervised and weakly-supervised segmentation task scenarios. We apply these methods and investigate the
results with the PASCAL VOC dataset