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Physical Sciences and Mathematics Commons™

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Environmental Sciences

Western University

2019

Articles 1 - 12 of 12

Full-Text Articles in Physical Sciences and Mathematics

The Stability Of Temperate Lakes Under The Changing Climate, Aleksey Paltsev Sep 2019

The Stability Of Temperate Lakes Under The Changing Climate, Aleksey Paltsev

Electronic Thesis and Dissertation Repository

There is a collective prediction among ecologists that climate change will enhance phytoplankton biomass in temperate lakes. Yet there is noteworthy variation in the structure and regulating functions of lakes to make this statement challengeable and, perhaps, inaccurate. To generate a common understanding on the trophic transition of lakes, I examined the interactive effects of climate change and landscape properties on phytoplankton biomass in 12,644 lakes located in relatively intact forested landscapes. Chlorophyll-a (Chl-a) concentration was used as a proxy for phytoplankton biomass. Chl-a concentration was obtained via analyzing Landsat satellite imagery data over a 28-year period (1984-2011) and using …

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Climate Change And Dissolved Organic Matter In Subarctic Lakes: Relevance To Methylmercury Bioavailability, Kyra Lyn Simone Sep 2019

Climate Change And Dissolved Organic Matter In Subarctic Lakes: Relevance To Methylmercury Bioavailability, Kyra Lyn Simone

Electronic Thesis and Dissertation Repository

One of the first steps of methylmercury (MeHg) bioaccumulation, uptake by phytoplankton, is regulated by dissolved organic matter (DOM). Methylmercury binds strongly with DOM, especially high-molecular weight (HMW) compounds containing reduced sulphur; this binding decreases MeHg bioavailability. Climate-induced changes were measured at the landscape level using ArcGIS; land-cover changes between 2005-2010 were assessed around lakes in Mackenzie Valley, NWT. The observed changes, a 10% increase in forest-classified area and up to 15% decrease in wetland area, will likely increase delivery of HMW DOM and MeHg to lakes. Partitioning experiments were conducted to examine effects of DOM ligand quality on MeHg …

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Microgrid Technology And The Arctic: Green Renewable Technology Does Relate To The Land, Gerry Dell Aug 2019

Microgrid Technology And The Arctic: Green Renewable Technology Does Relate To The Land, Gerry Dell

2019 Cohort

Microgrids can take power from other energy sources and share their loads meaning there is a less reliance on diesel power generation. Wind mill power generators, solar power (for the summer) and battery storage are fantastic elements for providing consistent power in the Arctic. These power systems have been tried and proven, in all conditions, over many years. Geothermal is another green efficient way to heat homes and businesses in the Arctic. When I worked for Dome Petroleum in McKinley Bay NWT, I was fortunate to work in the most extreme winter weather the Arctic can produce. With global warming …

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Microgrid Technology And The Arctic: Green Renewable Technology Does Relate To The Land, Gerry Dell Aug 2019

Microgrid Technology And The Arctic: Green Renewable Technology Does Relate To The Land, Gerry Dell

Head and Heart Posters 2019

Microgrids can take power from other energy sources and share their loads meaning there is a less reliance on diesel power generation. Wind mill power generators, solar power (for the summer) and battery storage are fantastic elements for providing consistent power in the Arctic. These power systems have been tried and proven, in all conditions, over many years. Geothermal is another green efficient way to heat homes and businesses in the Arctic. When I worked for Dome Petroleum in McKinley Bay NWT, I was fortunate to work in the most extreme winter weather the Arctic can produce. With global warming …

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Microgrid Technology And The Arctic: Green Renewable Technology Does Relate To The Land, Gerry Dell Aug 2019

Microgrid Technology And The Arctic: Green Renewable Technology Does Relate To The Land, Gerry Dell

Learning with your Head & Heart

Microgrids can take power from other energy sources and share their loads meaning there is a less reliance on diesel power generation. Wind mill power generators, solar power (for the summer) and battery storage are fantastic elements for providing consistent power in the Arctic. These power systems have been tried and proven, in all conditions, over many years. Geothermal is another green efficient way to heat homes and businesses in the Arctic. When I worked for Dome Petroleum in McKinley Bay NWT, I was fortunate to work in the most extreme winter weather the Arctic can produce. With global warming …

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Giant Beaver Palaeoecology Inferred From Stable Isotopes, Tessa Plint, Fred J. Longstaffe, Grant Zazula May 2019

Giant Beaver Palaeoecology Inferred From Stable Isotopes, Tessa Plint, Fred J. Longstaffe, Grant Zazula

Earth Sciences Publications

This is a multi-individual (n = 11), stable carbon and nitrogen isotope study of bone collagen (δ13Ccol and δ15Ncol) from the giant beaver (genus Castoroides). The now-extinct giant beaver was once one of the most widespread Pleistocene megafauna in North America. We confirm that Castoroides consumed a diet of predominantly submerged aquatic macrophytes. These dietary preferences rendered the giant beaver highly dependent on wetland habitat for survival. Castoroides’ δ13Ccol and δ15Ncol do not support the hypothesis that the giant beaver consumed trees or woody …

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Future Changes Of Hydroclimatic Extremes In Western North America Using A Large Ensemble: The Role Of Internal Variability, Mohammad Hasan Mahmoudi Apr 2019

Future Changes Of Hydroclimatic Extremes In Western North America Using A Large Ensemble: The Role Of Internal Variability, Mohammad Hasan Mahmoudi

Electronic Thesis and Dissertation Repository

Increases in the intensity and frequency of extreme events in Western North America (WNA) can cause significant socioeconomic problems and threaten existing infrastructure. In this study we analyze the impacts of climate change on hydroclimatic extremes and assess the role of internal variability over WNA, which collectively drain an area of about 1 million km2. We used gridded observations and downscaled precipitation, maximum and minimum temperature from seven General Circulation Models (GCMs) that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and a large ensemble of CanESM2 model simulations (CanESM2-LE; 50 members) for this analysis. Spatial …

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Evaluating Restoration Success By Tracking The Structural And Functional Recovery Of Restored, Drained, And Intact Wetlands, Renee C. Howard Apr 2019

Evaluating Restoration Success By Tracking The Structural And Functional Recovery Of Restored, Drained, And Intact Wetlands, Renee C. Howard

Electronic Thesis and Dissertation Repository

Wetland restoration efforts have increased on the Canadian prairies to compensate for widespread loss of wetland area, form, and function. Restoration activity presumes a direct replacement for natural wetlands, where restored wetlands provide equivalent ecological functions and services. However, restoration projects often show limited recovery success in biological structure and biogeochemical function. Using plant functional traits is an emerging approach to assessing ecological process and may provide a better indicator of wetland functional recovery than vegetation structural indicators alone. Here, I tracked vegetation structural metrics (i.e., species richness, composition, and cover) and plant functional traits over a chronosequence of restored …

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Optimal Algorithms For Deriving Estimates Of Phytoplankton Biomass In Lakes From Landsat Satellite Imagery, Michael A. Dallosch Apr 2019

Optimal Algorithms For Deriving Estimates Of Phytoplankton Biomass In Lakes From Landsat Satellite Imagery, Michael A. Dallosch

Electronic Thesis and Dissertation Repository

The frequency, intensity, and geographical distribution of harmful phytoplankton blooms are on the rise globally. There is a scientific need for estimates of historical and current phytoplankton data. This research develops mathematical algorithms for accurate assessment of surface chlorophyll-a (chl-a), a proxy for phytoplankton biomass, within freshwater lakes. Landsat satellite images (4-5 TM, 7 ETM and 8 OLI) were used to create predictive models (from 1984 to 2017) for seven ecoregions (ranging from the tropics to arctic). Correlation tests for 82 algorithms were conducted to establish the best fit models (linear, exponential, logarithmic, power) for chl-a …

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Tree-Ring Isotopes Adjacent To Lake Superior Reveal Cold Winter Anomalies For The Great Lakes Region Of North America, Steven L. Voelker, Simon S.-Y Wang, Todd E. Dawson, John S. Roden, Christopher J. Still, Fred J. Longstaffe, Avner Ayalon Mar 2019

Tree-Ring Isotopes Adjacent To Lake Superior Reveal Cold Winter Anomalies For The Great Lakes Region Of North America, Steven L. Voelker, Simon S.-Y Wang, Todd E. Dawson, John S. Roden, Christopher J. Still, Fred J. Longstaffe, Avner Ayalon

Earth Sciences Publications

Tree-ring carbon isotope discrimination (Δ13C) and oxygen isotopes (δ18O) collected from white pine (Pinus strobus) trees adjacent to Lake Superior show potential to produce the first winter-specific paleoclimate reconstruction with inter-annual resolution for this region. Isotopic signatures from 1976 to 2015 were strongly linked to antecedent winter minimum temperatures (Tmin), Lake Superior peak ice cover, and regional to continental-scale atmospheric winter pressure variability including the North American Dipole. The immense thermal inertia of Lake Superior underlies the unique connection between winter conditions and tree-ring Δ13C and δ18O …

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Stable Isotopes Of Clay Minerals From Autoclave Tests Of Oil Sands: Implications For Clay Formation During Steaming Of Alberta Clearwater Oil Sands, Shaoneng He, Fred J. Longstaffe, Zhihong Zhou Jan 2019

Stable Isotopes Of Clay Minerals From Autoclave Tests Of Oil Sands: Implications For Clay Formation During Steaming Of Alberta Clearwater Oil Sands, Shaoneng He, Fred J. Longstaffe, Zhihong Zhou

Earth Sciences Publications

In an effort to evaluate mineral-water isotopic exchange during cyclic steam stimulation (CSS), solutions and<2 μm berthierine-dominated solids from the Clearwater Formation oil sands of Alberta, Canada were analyzed for stable isotope compositions before and after reaction in autoclaves for 1008 h at 250 °C. There was no significant change in solution δ18O and δ2H, which is consistent with the high water/mineral ratio used in the experiments. The solids showed a marked decrease in both δ18O and δ2H following the experiments. Pre-run solids have δ18O of +9.5 to +12.9‰and …

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Reframing The Mammoth Steppe: Insights From Analysis Of Isotopic Niches, Rachel Schwartz-Narbonne, Fred J. Longstaffe, Kevin J. Karydynal, Patrick Druckenmiller, Keith A. Hobson, Christopher N. Jass, Jessica Z. Metcalfe, Grant Zazula Jan 2019

Reframing The Mammoth Steppe: Insights From Analysis Of Isotopic Niches, Rachel Schwartz-Narbonne, Fred J. Longstaffe, Kevin J. Karydynal, Patrick Druckenmiller, Keith A. Hobson, Christopher N. Jass, Jessica Z. Metcalfe, Grant Zazula

Earth Sciences Publications

Woolly mammoth (Mammuthus primigenius), horse (Equus spp.) and bison (Bisonspp.) coexisted with a variety of mammalian megafauna across the Pleistocene mammoth steppe e a megacontinental ecosystem that spanned northern Eurasia and northwestern North America. Previous research has suggested that highly conserved niches with minimal niche overlap allowed high levels of species diversity on the mammoth steppe. Here we evaluate previously published and some new collagen carbon and nitrogen isotope data (delta13C, delta15N) for mammoth steppe megaherbivores using Stable Isotope Bayesian Ellipses in R (SIBER) and linear regression models to determine isotopic …

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