Channel Form and Processes in a Formerly Glaciated Terrain

Despite that many places around the world in general, and North America in particular, were glaciated during the last ice age, relatively little is known about rivers that evolved over these landscapes once they deglaciated. These rivers are commonly categorized as alluvial with a glacial legacy, and often described as plain gravel-bed or sand-bed rivers. Alternatively, they are considered to be bedrock rivers when the glacial deposits were eroded and underlying rock was exposed. However, ignoring the glacial history of these rivers is scientifically wrong and they should be termed semi-alluvial . This work shows that classification is important, not only for scientific accuracy but for river management that must be based on a sound understanding of river form and process. Poor understanding can be costly, leading to wasted resources and inefficient functioning of the river. Two major geomorphologic phases can be discerned in formerly glaciated terrains: 1. Deglaciation which exposed the landscape to erosion when ponded meltwater was abundant and led to outburst flooding. These catastrophic floods cannot occur under the modern climate of southern Ontario. Evidence for glacial lakes is found in lacustrine deposits upstream, and on top of moraines while spillways indicate where glacial lakes drained and carved deep valleys into the subdued terrain. Spillways reveal outburst flooding with boulder lags, terraces, flow scars and possibly mounds and berms away from the modern misfit channel. 2. Postglacial incision and deposition during a single flood event or a single hydrological year. Human disturbance over the past two centuries, includes agriculture, channelization, millponds and weirs. The dissertation has two parallel paradigms in fluvial geomorphology: Which processes are responsible for most geomorphic work that shapes the landscape - catastrophic flood(s) or smallscale erosion and deposition that bit by bit give the channel and valley its present morphology. My work will show that the outburst flooding of Glacial Lake London (paper 1) sets the stage for the postglacial morphology and small-scale processes we see today (paper 2). The third paper attempts to explain these small-scale processes using a 1D hydraulic model that can answer dynamic questions like bankfull discharge, water surface slopes of discharges, and velocity reversal hypothesis

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Accidental Fires and Radiation Heat Transfer: Investigating the Effects of Flame Impingement on Structures

Accidental fires and their effects on the structural integrity of buildings are responsible for significant loss of human lives, economic assets, and environmental resources in the United States and across the globe. One cause of the collapse of the World Trade Center and the collapse of the Deepwater Horizon drilling platform in the Gulf of Mexico was the failure of structural materials under large heat loads from fires. Flame impingement or flame structure interaction studies are essential for understanding the effects of fire on the structural integrity of buildings. Radiation is an important mode of heat transfer to the structural element, and measurements of radiation intensities from the flame are useful for improving the understanding of heat transfer from the flame to the structure. This study investigates the radiation intensities and radiation heat flux from flames with and without impingement on a flat steel plate based on plate location relative to burner, fuel mass flow rate, and fuel type. The quantitative comparison between measured radiation intensities of impinging and non-impinging flames shows significant increases in radiation intensities near the surface of the plate. The radiation heat flux to the environment is lower for impinging flames, indicating high heat transfer to the plate. Quantitative knowledge gained from this study can be used to estimate structural integrity under large heat loads and to manufacture structural elements that are more resistant to fire

Comparison of Novel Biochars and Steam Activated Carbon from Mixed Conifer Mill Residues

There is increasing demand in environmental remediation and other sectors for specialized sorbents made from renewable materials rather than hard coals and minerals. The proliferation of new pyrolysis technologies to produce bio-based energy, fuels, chemicals, and bioproducts from biomass has left significant gaps in our understanding of how the various carbonaceous materials produced by these systems respond to processes intended to improve their adsorption properties and commercial value. This study used conventional steam activation in an industrial rotary calciner to produce activated carbon (AC) from softwood biochars made by three novel pyrolysis systems. Steam was injected across four heating zones ranging from 816 °C to 927 °C during paired trials conducted at calciner retention times of 45 min and 60 min. The surface area of the three biochars increased from 2.0, 177.3, and 289.1 m2 g−1 to 868.4, 1092.9, and 744.8 m2 g−1, respectively. AC iodine number ranged from 951 to 1218 mg g−1, comparing favorably to commercial AC produced from bituminous coal and coconut shell. The results of this study can be used to operationalize steam activation as a post-processing treatment for biochar and to expand markets for biochar as a precursor in the manufacture of specialized industrial sorbents

Sedimentary Characteristics of a Course Gravel-Bed River Choked with Fine Sediment, West Walker River, California

Systematic bed material measurements of 15 macro-bedforms in the West Walker River in eastern California demonstrate that the channel is enriched with fine sediment (\u3c 2 mm). Along 15 km of the stream system, bed material varies from sand to boulders in the upstream canyon exit from the Sierra Nevada, fines downstream in Antelope Valley to cobbles and fines. Fines become the dominant sedimentary fraction downstream to Smith and Mason Valleys. The stream network is heavily impacted by irrigation diversions and off-channel storage into Topaz Lake reservoir, and the manipulated hydrology affects the bed material distribution by reducing the river\u27s competence to transport coarser fractions, especially during high flows. As a result, the intervening agricultural valleys are aggradational. The river bed in Antelope Valley is heavily armored (1 or more orders of magnitude) in the macro-bedforms (bars, riffles and pools), but the abundance of fines does not only appear in the subsurface layers but also in forced and free patches within the surface layer. Furthermore, the New Year\u27s flood of 1997, the largest flood on the modern gauged record that occurred in the basin (estimated RI between 100-400 year) induced large amounts of fine sediment still deposited along the floodplains and large overbank bars. These deposits are only activated during bankfull and overbank flows and contribute additional fines to the stream system. Based on these results, we conclude the river bed is highly unstable and very active. While this is partially a result of a natural sedimentation process, the intensive anthropogenic water allocation does not allow the river to efficiently evacuate and propagate the sediment downstream, recover from the large-scale disturbance, and return to a quasi-equilibrium geomorphic state. Even in the minor human disturbance part of the upper basin, the river\u27s background amounts of fines are very large with repercussions for any decisions about river restoration of the lowland valleys

LIFE-CYCLE ASSESSMENT OF ACTIVATED CARBON FROM WOODY BIOMASS

Activated carbon (AC) developed and marketed for water and gas purification is traditionally made from hard coals (fossil-based materials). However, increasing awareness of environmental impacts caused by fossil fuel consumption and fossil-based products has provided a market opportunity for renewable and low-impact biobased products as alternatives including AC. The huge volumes of woody biomass generated from forest management activities could be used as feedstocks for these new bioproducts. These new bioproducts require evaluation to determine if they are low impact. To aid in quantifying environmental impacts of a new bioproduct (such as AC), this study developed the cradle-to-gate life cycle inventory (LCI) data for the carbon activation of biochar in a rotary calciner by collecting operational and direct emission data while conforming to the internationally accepted life cycle assessmentmethod. The LCI datawere then modeled to develop the life cycle impact assessment profile of biochar-based carbon activation and compared with commercial coal-based carbon activation. The results showed about 35% less cradle-to-product gate cumulative energy demand for the biochar AC system compared with the coal AC system. Consequentially, the greenhouse gas emissions for biochar AC production were less than half that of coal AC production (8.60 kg CO2 eq vs 18.28 kg CO2 eq per kg of AC produced). This was because of both lower energy consumption and the biogenic carbon benefit from using woody biomass for both feedstock and processing. To ensure substitution of the two ACs, the physical properties for the AC from biochar and coal were compared for their Brunauer–Emmett–Teller surface area and iodine number, which showed that both indicators were superior for biochar AC compared with coal AC. Therefore, biochar AC results from this study suggest a potential high-value market for woody biomass derived from forest restoration and wildfire suppression activities.