iSPEAC (invited Speakers in Physics, Environmental science, And Chemistry) is the Department of Physical and Environmental Science’s invited speaker series, which covers topics and is delivered by external experts and academics in physics, environmental science, and chemistry. Speakers from near and far are invited to share their cutting-edge research with an interdisciplinary audience of students, faculty and staff. The series is co-sponsored by the Department of Physical and Environmental Science, and the Office of the Vice-Principal Research at UTSC.
September 23, 2021 1:00 to 2:30pm via Zoom
Title: Opportunities for diversification and carbon storage within riparian agroecosystems: an overview of field – laboratory studies
Abstract: Riparian agroecosystems are becoming a more popular site across North American agricultural landscapes as they can provide a host of ecosystem services including nutrient and soil retention to improve water quality, carbon storage through increased biomass production and increased diversification within homogenous ecosystems. The delivery of these services is inherently tied to the plant communities within them; however, these systems are highly diverse, ranging from natural grasslands – old growth forests. In addition, there is very little information regarding riparian plant communities and their role in soil C storage. We show that by using plant functional traits to characterize plant community structure, we can more accurately understand the underlying mechanisms involved in carbon cycling. This presentation will examine work from all four of my PhD studies which have assessed plant trait diversity and carbon cycling within field sites as well as controlled incubation experiments.
Biography: Serra-Willow is completing the final year of her PhD (fingers crossed) in the department of physical and environmental science, supervised by Dr. Marney Isaac. Her work broadly looks at riparian agricultural systems and the role that plant functional trait diversity and community characteristics plays in carbon and nitrogen cycling, with the hopes of helping to design and manage agricultural systems that are more biodiverse, sustainable and profitable for farmers.
Title: Biofilm growth leads to buoyancy changes of microplastics in a freshwater environment
Abstract: Microplastic pollution has opened a Pandora’s box of issues, one of which is microplastic buoyancy change. Microplastic dispersal in the Great Lakes is heavily dependent on the physical properties of microplastic particle density and shape, but these can change due to surface growth of microbial communities (biofilms). Biofilm-induced changes of microplastic rising and sinking rates were investigated and quantified through laboratory experiments. It was observed that initially buoyant plastics can become negatively buoyant and quickly sink within a summer season. The smallest (125-212 microns) microplastics sank within 18 days of entering our freshwater system while the largest (1000-2000 microns) microplastics began sinking after 50 days. Because of the size-dependence of settling onset times, it is expected that a size-fractionation of microplastics deposition would occur where smaller particles are deposited closer to their sources relative to larger particles.
Biography: Patricia Semcesen is currently doing her Ph.D. research under the supervision of Dr. Mathew Wells at DPES. Her research focuses on the transport of plastic pollution in the Great Lakes. Through her research, she explored the effects of particle shape and biofilm formation on microplastic particle terminal velocity and the implications for microplastic transport and deposition. Currently, she is researching the transport of plastic debris in Toronto Harbour using GPS-tracked plastic bottles, in partnership with the UofT Trash Team (https://uofttrashteam.ca/taggingtrash/).
Title: Detection and description of spatiotemporal patterns in multi-day extreme weather events across Canada
Abstract: As the global climate continues to warm, changes in the characteristics of prolonged “blocking” weather events (periods of days or weeks with similar weather conditions) have been observed. This work-in-progress study examines the incidence of hot, cold, or mild days across Canada, to detect multi-day cold snaps, heat waves, and wintertime “warm spells” using novel station-specific thresholds for local extreme temperatures. We show that–over the period from 1986 to 2020–stations across Canada experienced multi-day (2+) periods with temperatures above their local relative extreme temperature thresholds, with apparent regional correlation among the events. We did not identify obvious temporal or spatial patterns in heat waves or wintertime warm spells. However, our Mann—Kendall analysis shows cold snaps to be shorter, fewer, and warmer, particularity in Atlantic Canada. We believe that the local relative extreme temperature mechanism represents an interesting metric for further study and refinement.
Biography: Conor Anderson is a climate scientist and PhD Candidate in the Gough lab. Conor's doctoral research has focused on quantitative analyses in climatology in Peru and across Canada.
Title: Assessment of temperature impacts on natural organic matter composition in bentonite for used nuclear fuel storage
Abstract: Bentonite clay (MX-80; Wyoming, USA) is proposed as a buffer layer within the engineered barrier systems for the long-term storage of used nuclear fuels in a deep geologic repository. The natural organic matter (NOM) is present in the mined bentonite may serve as microbial substrates and promote corrosion of the used fuel container. The NOM found in MX-80 is diagenetically altered, however, there is limited knowledge about how NOM in bentonite may change with temperature when exposed to used nuclear fuels. In this presentation, I used molecular-level techniques to analyze the NOM compositional differences in MX-80 with different temperatures (30-105 ℃) and times (90 ℃ for 3-42 days). Total organic carbon (TOC) and water-extractable organic carbon (WEOC) concentration, targeted NOM compound analysis and nuclear magnetic resonance (NMR) spectroscopy were used to determine if NOM composition was altered with incubation.
Biography: Phoebe Tong is currently doing her Ph.D. study under the supervision of Dr. Myrna Simpson at the Department of Physical and Environmental Sciences since 2018. Her thesis title is the investigation of anthropogenic progress on the molecular composition and stability of NOM in agroecosystems and a deep geologic repository setting. Her first two projects were focusing on the changes in soil organic matter biogeochemistry and stability in response to land-use change and agricultural management. The current and upcoming projects are investigating if NOM biogeochemistry in MX-80 bentonite clay will be altered when exposed to used nuclear fuels (i.e., temperature and radiation) which may decrease the reliability of the long-term storage.
Title: Following the path of seed microbiota in the Romaine lettuce microbiome
Abstract: The seed is a significant contributor of the Lactuca sativa plant’s core microbiota. A comparison of the 16S and 18S gene composition of Lactuca sativa seeds, seedlings, and leaves, as well as randomly sampled commercial leaves was performed in order to determine if a seed derived and shared core microbiome exists. Core seed microbiota appear to be shared across species, between plant compartments, and abundances vary according to stage of plant growth. Organic and Conventional cultivars were chosen to determine if there is a difference in core microbiota between farming methods or cultivar. Two cultured bacteria were found across most samples and network analysis shows key associations in balancing the microbiome.
Biography: I am a PhD candidate entering my 6th year of a direct-entry PhD in Environmental Sciences. I am supervised by Dr. Roberta Fulthorpe and our work is primarily in the field of Microbial Ecology. I currently study plant microbiota (endophytes), which play an important role in plant growth promotion and overall plant health. It is a newer area of study and my research focuses on seed endophytes and the pathway they take during the plant life cycle. Seed endophytes are a neglected topic but research suggests that they are a primary source of plant-associated bacteria in the plant microbiome. Plant’s vertically transmit these microbes via seeds from one generation to the next. My studies look at the path they take from seed to plant, which key microbes are seed derived, where they travel in the plant, their changing abundance and potential role in various plant compartments including the rhizosphere.
Title: Development of a Bayesian modelling framework to study the effects of hydrological extremes under present and future climate condition
Abstract: There is compelling evidence from many recent modelling studies that global warming will likely amplify the hydrological cycle. The intensification of hydrological extremes can alter the water availability and quality and make it more challenging for human societies and natural ecosystems to adapt. My thesis aims to develop an ensemble of modelling tools to address critical questions targeting the eutrophication issues in the Bay of Quinte, a system that has undergone a multitude of anthropogenic stressors (urbanization, agriculture) in its watersheds. Here, I will first introduce the work from my first chapter, which involves the application of the widely employed watershed model: the Soil and Water Assessment Tool (SWAT). I will then capitalize upon the Bayesian hierarchical modelling framework to test for thresholds in the behaviour of the Bay of Quinte watersheds. My research plan will then involve the characterization of biogeochemical processes and evaluation of multiple climate change and urbanization scenarios.
Biography: Aisha Javed is a third year doctoral student under the supervision of Dr. George Arhonditsis in the Department of Physical and Environmental Sciences at the University of Toronto Scarborough. Her thesis work focuses on watershed modelling, particularly in areas of concern that drain into Lake Ontario, such as the Bay of Quinte. Aisha’s work from the Ecological Modelling lab attempts to provide scientifically robust projections of the effects of management alternatives to Provincial and Federal Agencies for decision making purposes.
Title: Development of Low-Magnetic Susceptibility Micro-coils via 5-axis Machining for Analysis of Biological Samples
Abstract: Microcoils produced from materials with near-zero magnetic susceptibility showed improved lineshape in NMR Spectroscopy. This is important when developing prototype microcoils for intact mass-limited biological samples, where 2D NMR is required to increase spectral dispersion and reduce signal overlap (allowing for proper identification of metabolites). It was demonstrated that a 1H-13C tuned bronze Slotted-Tube Resonator (produced using 5-axis CNC machining) provided better lineshape compared to one machined from pure copper. This is due to the aluminum within the bronze offsetting the magnetic susceptibility of the copper. In this presentation, multiple methods will be employed to reduce the impact of magnetic susceptibility on lineshape. The resonators with the best lineshape will be used to analyze a variety of mass-limited biological samples.
Biography: As a 4th year PhD candidate at the University of Toronto Scarborough Campus (within Professor Andre Simpson's Research Group), my graduate work involves the application of CNC micromachining in the creation of microcoils/microsensors to enhance the mass-sensitivity of NMR Spectroscopy. These microcoils (miniaturized versions of the main "sensor" of the NMR Spectrometer) will eventually be used to analyze the metabolic profile of a wide variety of mass-limited biological samples (including eggs of small aquatic organisms, whole Daphnia manga organisms, etc.) to better understand their response to sub-lethal concentrations of environmental contaminants. The enhanced versatility of CNC micromachining allows for these microcoils to not only be produced in-house but also tailored to intended mass-limited biological samples to maximize signal from the sample. My undergraduate research experience (completed Spring 2016) also involved investigating the role of TRPM7 in B lymphocyte development, the production of recombinant HIV envelope proteins for use in HIV research, and optimizing an ELISA protocol for detecting HIV-reactive antibodies.
Title: Long-term litter manipulation alters soil carbon molecular biogeochemistry in an old-growth coniferous forest
Abstract: Global environmental change is altering the quality and quantity of plant inputs into soil. However, it is unclear how these long-term changes may fundamentally shift the biogeochemistry of soil carbon in forests. To better understand how varied detrital inputs alter soil organic matter (OM) molecular biogeochemistry, soil samples were collected from a 20 year detrital manipulation experiment in an old-growth coniferous rainforest in Western Oregon. The experiment includes ambient (control) plots and 5 treatments: Double Litter, Double Wood, No Roots, No Litter and No Inputs. Soil carbon and nitrogen, molecular-level OM composition using solid-state 13C nuclear magnetic resonance (NMR), and targeted analysis of plant- and microbial-derived compounds were measured. I will present how litter additions and exclusions altered soil OM composition and cycling in the long-term, particularly the key control of above-ground litter in changing soil carbon biogeochemistry trajectories.
Biography: Meiling Man is currently doing her PhD study under the supervision of Dr. Myrna Simpson at the Department of Physical and Environmental Sciences since 2017. Her PhD research focuses on the changes in soil organic matter biogeochemistry and cycling in managed ecosystems. Specifically, her studies investigated soil organic matter compositional change and degradation in response to different agricultural managements (i.e., crop rotation, tillage, N fertilization) and how detrital manipulation alters soil carbon dynamics in forest ecosystems.
Title: Greenhouse gas measurements in the Greater Toronto Area
Abstract: The Greater Toronto Area is the most populated city in Canada, thus accurately quantifying GHG emissions from the GTA is an important step towards meeting Canada's commitments to reduce its Greenhouse gas emissions. Mitigation of methane (CH4) emissions is of particular importance when setting the country's policy measures to meet the GHG reduction goal since it can be economically advantageous. In this study, a methane emission inventory with a high spatial resolution was prepared using individual facility reports gathered for each municipality in the GTA. In-situ measurements using stationary and portable instruments and total column measurements using Fourier Transform Spectrometers (FTS), are then used to monitor GHG levels in the GTA. The measurement results are then used to evaluate and improve the existing emission inventory.
Bio: Nasrin obtained her BSc in Physics from Sharif University of Technology, Iran and her MSc in Physics from the University of Calgary. Her Master's thesis was on atmospheric CO2 leak detection from Carbon Capture and Storage sites. Her research involved laboratory experiments, instrument design, field experiments and air dispersion modelling. After working for two years as an air quality scientist in a consulting firm, she decided to return to academia as a PhD student by joining Dr. Debra Wunch group. The focus of her research is on development of a methane emission inventory for the Greater Toronto Area (GTA). The research involves total column measurements as well as in-situ measurements of methane in GTA.
Title: Ecology of the aquatic sedimentary carbon cycle
Abstract: Aquatic sediments represent the biggest active sink of organic carbon on Earth. The fate of this organic carbon is largely determined by the ability or microorganisms to break down organic carbon into more mobile CO2 and methane, which can then return to the hydro- and atmosphere. The ability of microorganisms to break down sedimentary organic carbon is controlled by environmental parameters, the chemical form in which the organic carbon is present, and the community structure of microorganisms. Here, I will present novel insights into the controls of the organic carbon cycle in sediments, including the role of adsorption, chemical reactivity, and physical shielding in long-term organic carbon preservation. In addition, I will show how interactions between redox conditions, organic carbon chemical composition, in many cases mediated by macrofaunal activity, determine the community structure of carbon-cycling sediment microorganisms. In this context, the influence of human behavior on the current and future size of the sedimentary organic carbon sink will be discussed, and key questions and areas of future research on the sedimentary carbon cycle proposed.
Title: Breaking through the barries: A multi-pronged strategy towards targeting biofilms
Abstract: Research in our group combines quantitative biofilm study with nanotechnology-based approaches to mitigate biofilm-related problems. In the first part of my talk, I will focus on our recent progress in engineering smart nanomaterial-based therapeutics (nanotherapeutics) that target bacteria via multiple killing mechanisms. Concurrent with our effort in designing effective nanotherapeutics, we are also developing nanoscale analytical tools to elucidate the mechanism of action of our engineered nanomaterial-based antimicrobials. In the second part of my talk, I will highlight the quantitative platform we developed that allows us to measure the mechanical properties of biofilms with nanometer resolution, without destroying them. I will end my talk with our exciting discovery that bacteria continue to feel the surface long after initial attachment. Overall, research efforts in our group are driven by the need to engineer new classes of materials and therapeutics that can inhibit bacterial fouling on surfaces.
Dr. Artur Izmaylov
Title: Quantum Computing for Chemistry
Abstract: The electronic structure problem is at the heart of our understanding of atomic and molecular electronic properties, which are so crucial for the rational molecular design of new chemical compounds and materials. Unfortunately, the computational cost of this problem scales exponentially with the system size and presents a great challenge for a classical computer. Recently, few methods have been developed to solve this problem on a quantum computer that promises chemical accuracy and better scaling with the system size. However, these methods are either too demanding to be implemented on currently available hardware or insufficiently accurate. In this lecture, I will discuss how my group addresses these shortcomings and provide the outlook for using quantum computers in predictive electronic structure calculations.
Title : "From bench to communities: participatory research on environmental factors and health"
Élyse Caron-Beaudoin is a new Assistant Professor in environmental health at the Department of Health and Society. She holds a graduate appointment at the Department of Physical and Environmental Sciences. During this seminar, Elyse will briefly present her research program entitled from bench to communities. Élyse uses toxicology, molecular biology, community-based research, environmental epidemiology and public health to investigate the associations between environmental factors and health. As part of her talk, Elyse will present her research regarding gestational exposure to contaminants associated with oil and gas extraction and birth outcomes in Northeastern British Columbia.
Dr. Mathew Wells
Title: "How does water circulate under the ice in the many frozen lakes of Canada?"
Abstract: Almost all lakes in Canada freeze, often for a substantial portion of the year. Despite the ubiquity of these iconic frozen lakes in the northern landscape, the extreme logistical challenges mean that winter physical and biological processes are far less studied that summer conditions. In this talk I will discuss the physical processes that drive circulation under lake ice, and how these influence important biological processes such as algal blooms and production of dissolved oxygen. I will speculate on how this influences fish habitat and describe a new field program that seeks to link lake physics and fish biology.
Bio: Mathew Wells is an associate professor, who joined the department of Physical and Environmental Sciences in March 2006. He undertook his PhD studies at the Australian National University, and held post-doctoral positions at the Eindhoven Technical University in the Netherlands and at Yale University in the USA before moving to Canada. His research group studies environmental fluid dynamics with a focus on how thermal stratification in lakes control mixing and dispersion rates. He works closely with numerous government agencies to better understanding how lake circulation influences fish habitat and water quality.
Dr. Alex Voznyy
How can machine learning help address climate change?
Solving the climate change crisis requires dramatic changes that can be achieved by policy, technology, or personal behavior. Significant improvements in the cost of technological solutions for renewable energy are still required to make them economically competitive with fossil fuels. This, in turn, requires modifications to the device design and materials employed. Parameter space for the discovery of new materials is vast and impossible to explore with conventional brute-force sampling, neither computationally nor experimentally. Machine learning is a new tool that allows us to learn the empirical rules connecting disparate experimental observations. Such interpolation allows us to explore the parameter space more efficiently and even employ the inverse design, i.e. predicting new materials with desired properties.
I will highlight how we use machine learning in our group for predicting and synthesizing new materials for solar cells, Li-ion batteries, and various catalysts
Alex earned his Ph.D. in physics of semiconductors from Chernivtsi National University, Ukraine for his work on electronic properties of nitride semiconductor alloys.
In 2004 he joined the Quantum Semiconductors and Bionanophotonics lab at University of Sherbrooke as a postdoc, working on theoretical modeling of laser-assisted quantum well intermixing and self-assembly processes of organic monolayers on metal and semiconductor surfaces for applications in bio-sensing.
In 2008 he moved to Quantum Theory Group at National Research Council of Canada in Ottawa, where he worked on many-body problems in epitaxial and colloidal semiconductor and graphene quantum dots; in particular, simulations of multi-exciton generation, Auger processes and optical properties of nanocrystals used in hybrid polymer-semiconductor solar cells.
Alex joined Ted Sargent’s Nanomaterials for Energy Group in 2011 and worked on characterization and modeling of the semiconductor nanocrystal surfaces and developing the synthesis methods for nanomaterials with improved optical and transport properties for photovoltaics.
In 2018, Alex joined the Department of Physical and Environmental Sciences at the University of Toronto, Scarborough as an Assistant Professor in Clean Energy. His topics of interest are materials for energy storage and novel materials discovery using high-throughput experiments and machine learning.
Dr. Marney Isaac
Title: The diversification of agroecosystems: uncovering indicators and outcomes
Abstract: Around the world, food production systems that rely on intensively managed single crops have tended to disrupt local and global biogeochemical cycles, reduce biodiversity, and make farming risky for ecosystems and for people. Simple strategies such as increasing biodiversity in the agricultural landscape can curb many of the negative impacts associated with current food production systems. I will present my research groups diagnostic approaches to assessing agroecosystem function, productivity and social-ecological outcomes in biologically complex agroecosystems.
Bio: Dr. Marney Isaac is a Professor in the Department of Physical and Environmental Sciences and the Centre for Critical Development Studies at the University of Toronto Scarborough, and the Department of Geography at the University of Toronto. Dr. Isaac holds the Canada Research Chair in Agroecosystems & Development. She serves as an Associate Editor for the Journal of Applied Ecology and the journal Agronomy for Sustainable Development. Dr. Isaac leads the Integrative Agroecology Lab, an interdisciplinary lab that addresses fundamental questions on the role of biodiversity in agroecosystems. Dr. Isaac is a specialist in the field of agroecology, with particular expertise in agroforestry systems. Her research provides insights into the plant-soil interactions that govern the structure and function of biologically complex agricultural landscapes. She also supervises an international research program investigating the role of agrarian networks in the adoption of agrobiodiversity.