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You searched for +publisher:"Duke University" +contributor:("Pratson, Lincoln F"). Showing records 1 – 3 of 3 total matches.

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Duke University

1. Worman, Stacey Lynn. Global Rates of Free Hydrogen (H2) Production by Serpentinization and other Abiogenic Processes within Young Ocean Crust .

Degree: 2015, Duke University

The main conclusion of this dissertation is that global H2 production within young ocean crust (<10 Mya) is higher than currently recognized, in part because current estimates of H2 production accompanying the serpentinization of peridotite may be too low (Chapter 2) and in part because a number of abiogenic H2-producing processes have heretofore gone unquantified (Chapter 3). The importance of free H2 to a range of geochemical processes makes the quantitative understanding of H2 production advanced in this dissertation pertinent to an array of open research questions across the geosciences (e.g. the origin and evolution of life and the oxidation of the Earth’s atmosphere and oceans). The first component of this dissertation (Chapter 2) examines H2 produced within young ocean crust [e.g. near the mid-ocean ridge (MOR)] by serpentinization. In the presence of water, olivine-rich rocks (peridotites) undergo serpentinization (hydration) at temperatures of up to ~500°C but only produce H2 at temperatures up to ~350°C. A simple analytical model is presented that mechanistically ties the process to seafloor spreading and explicitly accounts for the importance of temperature in H2 formation. The model suggests that H2 production increases with the rate of seafloor spreading and the net thickness of serpentinized peridotite (S-P) in a column of lithosphere. The model is applied globally to the MOR using conservative estimates for the net thickness of lithospheric S-P, our least certain model input. Despite the large uncertainties surrounding the amount of serpentinized peridotite within oceanic crust, conservative model parameters suggest a magnitude of H2 production (~1012 moles H2/y) that is larger than the most widely cited previous estimates (~1011 although previous estimates range from 1010-1012 moles H2/y). Certain model relationships are also consistent with what has been established through field studies, for example that the highest H2 fluxes (moles H2/km2 seafloor) are produced near slower-spreading ridges (<20 mm/y). Other modeled relationships are new and represent testable predictions. Principal among these is that about half of the H2 produced globally is produced off-axis beneath faster-spreading seafloor (>20 mm/y), a region where only one measurement of H2 has been made thus far and is ripe for future investigation. In the second part of this dissertation (Chapter 3), I construct the first budget for free H2 in young ocean crust that quantifies and compares all currently recognized H2 sources and H2 sinks. First global estimates of budget components are proposed in instances where previous estimate(s) could not be located provided that the literature on that specific budget component was not too sparse to do so. Results suggest that the nine known H2 sources, listed in order of quantitative importance, are: Crystallization (6x1012 moles H2/y or 61% of total H2 production), serpentinization (2x1012 moles H2/y or 21%), magmatic degassing (7x1011 moles H2/y or 7%), lava-seawater… Advisors/Committee Members: Pratson, Lincoln F (advisor).

Subjects/Keywords: Geology; Biogeochemistry; Geomorphology; Barchan Sand Dunes; Free Hydrogen Production; Global Estimates; Reduced Gases; Serpentinization; Sub-seafloor Microbes

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Worman, S. L. (2015). Global Rates of Free Hydrogen (H2) Production by Serpentinization and other Abiogenic Processes within Young Ocean Crust . (Thesis). Duke University. Retrieved from http://hdl.handle.net/10161/10490

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Worman, Stacey Lynn. “Global Rates of Free Hydrogen (H2) Production by Serpentinization and other Abiogenic Processes within Young Ocean Crust .” 2015. Thesis, Duke University. Accessed August 08, 2020. http://hdl.handle.net/10161/10490.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Worman, Stacey Lynn. “Global Rates of Free Hydrogen (H2) Production by Serpentinization and other Abiogenic Processes within Young Ocean Crust .” 2015. Web. 08 Aug 2020.

Vancouver:

Worman SL. Global Rates of Free Hydrogen (H2) Production by Serpentinization and other Abiogenic Processes within Young Ocean Crust . [Internet] [Thesis]. Duke University; 2015. [cited 2020 Aug 08]. Available from: http://hdl.handle.net/10161/10490.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Worman SL. Global Rates of Free Hydrogen (H2) Production by Serpentinization and other Abiogenic Processes within Young Ocean Crust . [Thesis]. Duke University; 2015. Available from: http://hdl.handle.net/10161/10490

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Duke University

2. Henry, Candise. Vulnerability of Coal- and Natural Gas-Fired Power Plants to Climate Change .

Degree: 2018, Duke University

Modeling studies predict that droughts and hotter water and air temperatures caused by climate warming will reduce the efficiency (η) of thermoelectric plants by 0.12-0.45% for each 1°C of warming. In Chapter 2, we evaluate these predictions using historical performance data for 39 open- and closed-loop, coal and natural gas plants from across the U.S., which operated under daily and seasonal temperature fluctuations multiples greater than future average warming projections. Seven to fourteen years of hourly water (Tw), dry-bulb air (Ta) and wet-bulb air (Twb) temperature recordings collected near each plant are regressed against efficiency to attain estimates of ∆η per 1°C increase. We find reductions in η with increased Tw (for open-loop plants) up to an order of magnitude less than previous estimates. We also find that changes in η associated with changes in Ta (open-loop plants) or Twb (closed-loop plants) are not only smaller than previous estimates but also variable, i.e. η rises with Ta or Twb for some plants and falls for others. Our findings suggest that thermoelectric plants, particularly closed-loop plants, should be more resilient to climate warming than previously expected. Moreover, our results raise questions regarding the relative impacts of climate change-induced drops in water availability versus increases in ambient temperatures on the ability of thermoelectric power plants to generate power. In Chapter 3, we explore and compare the effects of decreased water availability and increased water temperature on once-through power plants, which are expected to suffer more of the impacts of climate change than recirculating plants. Currently, little is known about which of the constraints, water temperature or availability, has a greater impact on power generation, and how these impacts and trends may vary with plant age, nameplate capacity, fuel type, generator technology, and location. We apply seven years of historical data from 20 once-through coal and natural gas plants into a thermoelectric power generation model to simulate how changes in various external parameters (water temperature, temperature regulations, and water availability) can affect the usable capacity of these plants. We find that depending on the plant, streamflow can contribute to 0-35% of the capacity reduction, while temperature can contribute 0-17% and regulations 48-100%. We also observe that power plants located on smaller water bodies (i.e., <3000 m3/s in this study) are more likely to be severely impacted in future climate extreme events than plants located in other areas, regardless of power plant technology. The fourth and final chapter of this dissertation diverges from the previous chapters and examines the processes that influence the evolution of fluvio-deltaic systems at passive continental margins. Depositional and erosional patterns that were previously believed to be entirely produced by externally-derived (allogenic) processes are now being recognized as patterns that can develop from autogenic… Advisors/Committee Members: Pratson, Lincoln F (advisor).

Subjects/Keywords: Energy; Water resources management; Geomorphology; Basin dynamics; Climate change adaptation; Fluvio-deltaic systems; Passive margin morphology; Power plant engineering; Thermoelectric power plants

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Henry, C. (2018). Vulnerability of Coal- and Natural Gas-Fired Power Plants to Climate Change . (Thesis). Duke University. Retrieved from http://hdl.handle.net/10161/16907

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Henry, Candise. “Vulnerability of Coal- and Natural Gas-Fired Power Plants to Climate Change .” 2018. Thesis, Duke University. Accessed August 08, 2020. http://hdl.handle.net/10161/16907.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Henry, Candise. “Vulnerability of Coal- and Natural Gas-Fired Power Plants to Climate Change .” 2018. Web. 08 Aug 2020.

Vancouver:

Henry C. Vulnerability of Coal- and Natural Gas-Fired Power Plants to Climate Change . [Internet] [Thesis]. Duke University; 2018. [cited 2020 Aug 08]. Available from: http://hdl.handle.net/10161/16907.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Henry C. Vulnerability of Coal- and Natural Gas-Fired Power Plants to Climate Change . [Thesis]. Duke University; 2018. Available from: http://hdl.handle.net/10161/16907

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Duke University

3. Doran, Elizabeth M. B. Theory and Practice in Sustainability Science: Influence of Urban Form on the Urban Heat Island and Implications for Urban Systems .

Degree: 2016, Duke University

As the world population continues to grow past seven billion people and global challenges continue to persist including resource availability, biodiversity loss, climate change and human well-being, a new science is required that can address the integrated nature of these challenges and the multiple scales on which they are manifest. Sustainability science has emerged to fill this role. In the fifteen years since it was first called for in the pages of Science, it has rapidly matured, however its place in the history of science and the way it is practiced today must be continually evaluated. In Part I, two chapters address this theoretical and practical grounding. Part II transitions to the applied practice of sustainability science in addressing the urban heat island (UHI) challenge wherein the climate of urban areas are warmer than their surrounding rural environs. The UHI has become increasingly important within the study of earth sciences given the increased focus on climate change and as the balance of humans now live in urban areas. In Chapter 2 a novel contribution to the historical context of sustainability is argued. Sustainability as a concept characterizing the relationship between humans and nature emerged in the mid to late 20th century as a response to findings used to also characterize the Anthropocene. Emerging from the human-nature relationships that came before it, evidence is provided that suggests Sustainability was enabled by technology and a reorientation of world-view and is unique in its global boundary, systematic approach and ambition for both well being and the continued availability of resources and Earth system function. Sustainability is further an ambition that has wide appeal, making it one of the first normative concepts of the Anthropocene. Despite its widespread emergence and adoption, sustainability science continues to suffer from definitional ambiguity within the academe. In Chapter 3, a review of efforts to provide direction and structure to the science reveals a continuum of approaches anchored at either end by differing visions of how the science interfaces with practice (solutions). At one end, basic science of societally defined problems informs decisions about possible solutions and their application. At the other end, applied research directly affects the options available to decision makers. While clear from the literature, survey data further suggests that the dichotomy does not appear to be as apparent in the minds of practitioners. In Chapter 4, the UHI is first addressed at the synoptic, mesoscale. Urban climate is the most immediate manifestation of the warming global climate for the majority of people on earth. Nearly half of those people live in small to medium sized cities, an understudied scale in urban climate research. Widespread characterization would be useful to decision makers in planning and design. Using a multi-method approach, the mesoscale UHI in the study region is characterized and the secular trend over the last sixty years… Advisors/Committee Members: Golden, Jay S (advisor), Pratson, Lincoln F (advisor).

Subjects/Keywords: Sustainability; Atmospheric sciences; Land use planning; local scale; mesoscale; sustainability; sustainability science; urban form; urban heat island

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Doran, E. M. B. (2016). Theory and Practice in Sustainability Science: Influence of Urban Form on the Urban Heat Island and Implications for Urban Systems . (Thesis). Duke University. Retrieved from http://hdl.handle.net/10161/12814

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Doran, Elizabeth M B. “Theory and Practice in Sustainability Science: Influence of Urban Form on the Urban Heat Island and Implications for Urban Systems .” 2016. Thesis, Duke University. Accessed August 08, 2020. http://hdl.handle.net/10161/12814.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Doran, Elizabeth M B. “Theory and Practice in Sustainability Science: Influence of Urban Form on the Urban Heat Island and Implications for Urban Systems .” 2016. Web. 08 Aug 2020.

Vancouver:

Doran EMB. Theory and Practice in Sustainability Science: Influence of Urban Form on the Urban Heat Island and Implications for Urban Systems . [Internet] [Thesis]. Duke University; 2016. [cited 2020 Aug 08]. Available from: http://hdl.handle.net/10161/12814.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Doran EMB. Theory and Practice in Sustainability Science: Influence of Urban Form on the Urban Heat Island and Implications for Urban Systems . [Thesis]. Duke University; 2016. Available from: http://hdl.handle.net/10161/12814

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.