| Dr. Shira Jouda | Spectroscopic advances in liana detection in tropical forests and future perspectives | 12:00 October 30th, 2024 | Zoom Link |
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Abstract
Lianas, woody vines that climb and intertwine with trees, play a crucial role in tropical forest ecosystems. They compete with trees for light, water, and nutrients. This competition often results in increased tree mortality and altered forest dynamics, affecting forest structure, carbon storage, and biodiversity. Given their significant impact, understanding lianas is essential to understand how tropical forests respond to climate change. Tropical forests exhibit varied responses to climate change, including increased tree mortality, faster turnover rates, and a rise in liana abundance. Lianas are among the ten most significant indicators of climate change in these environments. Consequently, detecting and monitoring lianas through remote sensing is one of the most complex challenges in tropical forest research. Over the past twenty-five years, field spectrometry research has developed techniques to identify lianas, albeit with limited success. Early studies examining liana spectral properties across dry and rainforest environments (400–1100 nm) revealed that lianas in dry forests are more distinguishable from their host trees than those in rainforests because of their distinct spectral, biophysical, and biochemical traits. This led to the discovery of a spectral/biophysical vegetation syndrome, which states that liana leaves can be separated from their host trees in dry forests but not rainforests. More recent research in the longwave infrared range (8000–14000 nm) utilizing machine learning approaches suggests that lianas can be differentiated independently of rainfall gradients. In this presentation, I summarize 25 years of research on liana spectroscopy and discuss the future potential of airborne and spaceborne hyperspectral sensors for liana identification.
| Dr. Shira Joudan | Trifluoroacetic acid in the environment: complexities of the smallest ‘forever chemical’ | 12:00 October 25th, 2024 | Access Recording | Passcode 8S2j*Ay@ |
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Abstract
There are growing concerns about the increasing concentrations of the trifluoroacetic acid (TFA) in the environment. TFA is the smallest in the class of per- and polyfluoroalkyl substances (PFAS), which are sometimes called ‘forever chemicals’ due to their extreme persistence. Some TFA is emitted directly into the environment, but most is formed from reactions of precursors including refrigerants and anaesthetics, and can be formed from fluoropolymers and other PFAS. An understudied source is pesticides and pharmaceuticals containing aromatic groups with CF3 substitutions (aryl-CF3). The amount of TFA in the environment is greater than what is expected based on known sources, and therefore, our research aims to understand the sources of TFA to the environment. In this talk, I will present results from two projects that study TFA in the atmosphere and in sunlit waters. Real-time (1 Hz) gas-phase measurements of TFA were made in Toronto in the winter and summer of 2022 using a chemical ionization mass spectrometer, reporting higher concentrations in the summer compared to winter. Correlations with solar irradiance and known photochemically produced pollutants suggest that the majority of the TFA measured in Toronto originates from volatile fluorinated chemicals that undergo photochemical reactions to form TFA, and that it is not emitted directly into the atmosphere. In sunlit waters, pesticides and pharmaceuticals containing aryl-CF3 have the potential to form TFA. We found that certain structures can yield up to 9% TFA, and that this value varies based on the pH of the solution. We also use a 13C-labelled isotopologue and high-resolution mass spectrometry to track how aryl-CF3 forms TFA by identifying key intermediates in the reaction.
| Dr. Karlis Muehlenbachs | Oxygen Isotope Composition of the Seas Through the Ages | 12:00 October 18th, 2024 | Access Recording | Passcode 9?!6jE0Y |
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Abstract
Discussions about seawater changed with acceptance of plate tectonics. Former paradigm that seawater composition reflected accumulation of salt followed by reverse weathering had to be modified to include seawater interactions with the seafloor, subduction and its participation in the growth of continents. I demonstrated (1971) that such processes set and buffer δ18O of seawater to its current value. Low temperature weathering on land and shallow parts of the ocean crust that enrich the products in 18O but strip it from the hydrosphere are balanced by addition of 18O by high temperature alteration at mid-ocean ridges where 18O is removed from the altered crust but added to seawater. “Black Smokers” show high temperature alteration of the ocean crust is prevalent at about 350 C. At that temperature the δ18O partitioning of the ensemble of alteration minerals in the altered basalt and water is approximately 6‰, setting a “buffer” on the δ18O of seawater itself to 0+/- 2 ‰ for all times plate tectonics operated. This appears incompatible with secular trend of decreasing δ18O in sediments with age. However, no secular δ18O trend is seen in ophiolites nor VMS ore deposits. If at least part of the sediment and fossil δ18O records are real, then the debate remains if the δ18O of seawater was not “buffered” or environmental temperatures were unexpectedly higher in the past? Recent, very detailed, as well as averaged, examination of δ18O carbonates and phosphates in the sedimentary record both show for the whole of Phanerozoic and late Proterozoic a constant δ18O of seawater near 0 ‰. Clumped isotope studies on carbonates and “triple oxygen” all indicate a δ18O Phanerozoic ocean near 0 ‰. The debate on the δ18O of Phanerozoic seawater is over, we have to accept and explain surprises in the climate record. The δ18O of the Archean ocean is not as certain. Recent studies give contradictory deductions of either a higher or lower δ18O than in the Phanerozoic. Resolution is needed to better understand the Earth’s earliest environment and life, the onset of modern plate tectonics, growth and emergence of continents and perhaps the Hadean ocean.
| Dr. Heather Graham | Life Detection and the Limits of Analog | 12:00 October 11th, 2024 | Access Recording | Passcode yhE6+0=7 |
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Abstract
A key goal in astrobiology is to search for life and signs of life (biosignatures) beyond our own planet, yet we are confronted with this challenge - how do we search for signs of life that may use an unknowable, unfamiliar biochemistry? Current strategies for biosignature detection rely mainly on identification of well-established and widely accepted features associated with contemporary life, such as particular classes of molecules and isotopic signatures, enantiomeric excesses, and patterns within the molecular weights of fatty acids or other lipids. While this may be a practical strategy it does represent a pronounced blind spot that may limit our ability to recognize biochemistry sufficiently different than our own, a potentially unfortunate assumption. Further, as we begin to explore farther out in the Solar System, where a common heritage with Earth is less likely, it becomes even more necessary to design generalized life detection approaches. It also becomes much more important to incorporate knowledge of the abiotic chemical, physical and geologic processes that provide environmental context for our observations. For example, the diverse organic chemistry of extraterrestrial materials could be interpreted as false positives for biomolecules on other planets. In this talk we will explore the fundamental features and mechanistic models of biological systems that focus on the unique way in which life rearranges matter and utilizes energetic inputs. Where definitions of life are lacking, descriptions of life that can be used to broaden our search patterns.
| Dr. Christopher Spencer | Biogeodynamics: the next step in crystal evolution | 12:00 October 4th, 2024 | Access Recording | Passcode 505163 |
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Abstract
There is a growing consensus that the evolution of tectonomagmatic processes played a central role in the evolution of life and the atmosphere. These processes supply bioessential nutrients to the hydrosphere and atmosphere which in turn facilitate radiation and proliferation of Earth’s biota. The emerging field of biogeodynamics examines the interactions between Earth's interior, surface, atmosphere, ocean, climate, and life. In this seminar, I will explore the variety of ways we can trace the influence of the lithosphere on the biosphere and atmosphere, but also how the latter actors influence the former. There is a strong correlation between the rise of continental freeboard and the flux of phosphorus to the oceans. This is directly followed by the oxygenation of the atmosphere which is traced by sulfur isotopes in sedimentary rocks which are in turn recycled in sediment-derived melts. Furthermore, evidence is mounting that the evolution of the biosphere on land is directly changing sedimentation patterns which also influence the composition of magmatic rocks. The next steps in testing these hypothesis will require synthesizing wide arrays of data that span numerous disparate disciplines and methodologies. This will include continued exploration in novel isotopic proxies that hold significant promise in testing biogeodynamic hypotheses.
| Dr. Kyle Whitfield | Community Deployment Planning Initiative Adresses Needs of Rural Men | 12:00 September 27th, 2024 | Access Recording |
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Abstract
Rural regions across North America continue to suffer from a lack of community-level mental health supports. This exploratory study explores whether Men’s Sheds, bottom-up, community-driven groups designed to support retired and older men’s mental health by mimicking the social and collaborative aspects of “work-life” by creating opportunities to engage in project-based woodworking, metalworking or mechanics, are generating positive mental health outcomes for their members in rural communities in Alberta, Canada. Relying on a set of semi-structured interviews with participants across two rural Alberta Men’s Sheds, in addition to a sociodemographic and self-rating questionnaire, we demonstrate that the participants in these Sheds enjoy clear and significant mental health benefits by generating opportunities for camaraderie, a sense of purpose and a sense of inclusion. Although not an appropriate substitute for more formal mental health supports in certain situations, we conclude that planning for the formation of new Men’s Sheds throughout rural areas represents a worthwhile investment in the mental health of a group of vulnerable citizens.
| Dr. Maya Rousteai | Advancing Soil and Rock Core Analysis: High-Resolution X-ray CT Scanning for Climate-Resilient Geotechnical Data | 12:00 September 20th, 2024 | Access Recording |
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Abstract
High-resolution X-ray Computed Tomography (CT) is a reliable, non-destructive technique for characterizing soil and rock cores. This presentation summarizes several years of research conducted at the Permafrost Archive Laboratory (PACs) at the University of Alberta, where frozen and unfrozen samples were scanned to reveal key physical properties such as density, volumetric/excess ice content, porosity distribution, thaw settlement, permeability, and thermal conductivity. The development of standardized and interoperable methods for soil characterization will enable more robust geotechnical datasets and support efforts to understand soil changes under expected climate conditions.
| Dr. Chris Herd | The Source Craters of the Martian Meteorites | 12:00 September 13th, 2024 | Access Recording |
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Abstract
There are currently approximately 200 distinct rocks from Mars in the form of martian meteorites. These samples are delivered to Earth through impact ejection from the martian surface. Where these rocks come from has been a question ever since they were recognized as being from Mars. In our recently-published study (Herd et al. 2024, Sci. Adv. 10, eadn2378) we combine the results of diverse sets of observations and modeling to constrain the source craters for five groups of the martian meteorites. We conclude that martian meteorites were derived from lava flows within the top 26 m of the surface, and we link the five groups - ejected at the same time from the same crater - to five specific source craters and geologic units.The study has implications for testing remote sensing-based volcanic models, for calibrating the chronology of Mars, and for linking other groups of meteorites - and meteorites yet to be discovered - to specific locations on Mars. In this way, we provide important context for the only samples of Mars available until robotically-collected samples are returned from the Red Planet.