Physical Sciences and Mathematics Commons^™

Topographic Influences On Trends And Cycles In Nutrient Export From Forested Catchments On The Precambrian Shield, Samson G. Mengistu

Electronic Thesis and Dissertation Repository

This dissertation explored topographic controls on spatial and temporal patterns in water yield and nutrient (carbon, nitrogen and phosphorus) export from forested headwater catchments in the Turkey Lakes Watershed in central Ontario, where other factors contributing to differences in water yield and nutrient export, including climate, geology, forest, and soils, are relatively constant. Topographic characteristics, including (a) hydrological flushing potential (expansion of water table into nitrate-N producing areas); (b) hydrological storage potential (area of wetlands, which can alternatively allow water and nutrients to bypass wetlands when storage capacity is filled with water or to trap them when not filled); and …

Co2 Injection Into A Deep Saline Aquifer: Porosity Measurements, Numerical Modeling, And Costs Associated With Uncertainty Of Petrophysical Parameters, Michael John Gragg

Masters Theses

Anthropogenic levels of atmospheric greenhouse gases, particularly carbon dioxide (CO₂) have increased rapidly over the last several decades and coincide with rising temperatures globally. One possible solution is to capture CO₂ before it is released into the atmosphere by large point sources, such as fossil fuel power plants. Once captured, the CO₂ can be condensed and transported to a storage facility. Of the available options for storage of condensed CO₂, geologic sequestration in deep saline aquifers is considered the most viable option.

Porosity measurements were obtained for nearly 100 core samples of the Knox …

Long-Term Effects Of Rice Rotation, Tillage, And Fertility On Near-Surface Soil Carbon And Nitrogen Cycling, Jill Marie Motschenbacher

Graduate Theses and Dissertations

Rice (Oryza sativa L.)-based cropping systems are different from other row crops due to the flood-irrigation scheme used from about one month after planting to a few weeks prior to harvest. The frequent cycling between anaerobic (i.e., flooding during the growing season) and aerobic (i.e., generally, the remainder of the year) conditions can influence the rate of soil organic matter (SOM) decomposition, which can greatly influence carbon (C) and nitrogen (N) storage and sequestration in the soil over time. Therefore, a study was conducted on a silt-loam soil (fine, smectitic, thermic, Typic Albaqualf) at the Rice Research and Extension Center …

The State Of Sustainable Transportation At Union College: A Transportation Audit Of Union College Students And Faculty, Benjamin Engle

Honors Theses

Union College has established a Climate Action Plan with the goal of carbon neutrality by 2060 as part of its commitment to sustainability. A significant component of Union’s carbon footprint, however, is student and faculty transportation. The purpose of this research was to analyze the transportation behavior of students and faculty to determine the carbon emissions that result from the use of various transportation methods. Two campus‐wide surveys were conducted; one was distributed to students and the other targeted faculty. For comparison purposes, survey questions were designed to be compatible with, but more focused than, those of a survey conducted …

Putting The Wind At Our Backs: Assessing U.S. Potential For 20% Wind Energy By 2030, Kevin T. Harnett

Honors Theses

The discussion surrounding the future of energy, particularly in the United States, has gained significant momentum in recent years for an obvious reason — it’s daunting. Our dependence on fossil fuels has positioned our nation in an undesirable predicament with a questionable future. With the associated consequences, principally Climate Change, it is essential that energy be addressed as a primary national concern. Renewables need to flip the switch.

Modeling Biofuel Production In Southern Pine Forests: The Effects On Soil Properties, Brittany L. Oakes

Honors Theses

From consuming energy alone in 2009, the United States ranked second as a carbon emitter at 5,425 million metric tons annually; China was the leader at 7,706 million metric tons and India placed third at 1,591 million metric tons (EIA, 2010). Yet in 2009, the U.S. consumed more electricity than both China and India and was the leading importer of electricity (EIA, 2010). Incorporating more domestic sources of renewable energy can simultaneously alleviate two issues: mitigating climate change catastrophes and significantly reduce our dependence on foreign markets for electricity and other forms of energy. Additionally, evidence of dwindling international oil …

The Carbon Budget Impact Of Sagebrush Degradation, Andrew Connor Austreng

Boise State University Theses and Dissertations

More than 20,000 km2 of sagebrush (Artemesia spp.) ecosystems within the Great Basin have been replaced, often following wildfire, by the nonnative winter annual cheatgrass (Bromus tectorum). At a field site in the central Snake River Plain of southern Idaho, the impact of this invasion on the soil carbon (C) reservoir has been evaluated and the potential soil C benefits of bunchgrass (Agropyron cristatum) seeding was assessed. Using a large soil C dataset (n = 850), differences in total organic carbon and root biomass were quantified in immediately-adjacent sagebrush, cheatgrass, and bunchgrass communities. Statistical …

Use Of Ultra High Vacuum Plasma Enhanced Chemical Vapor Deposition For Graphene Fabrication, Shannen Adcock

Graduate Theses and Dissertations

Graphene, what some are terming the "new silicon", has the possibility of revolutionizing technology through nanoscale design processes. Fabrication of graphene for device processing is limited largely by the temperatures used in conventional deposition. High temperatures are detrimental to device design where many different materials may be present. For this reason, graphene synthesis at low temperatures using plasma-enhanced chemical vapor deposition is the subject of much research. In this thesis, a tool for ultra-high vacuum plasma-enhanced chemical vapor deposition (UHV-PECVD) and accompanying subsystems, such as control systems and alarms, are designed and implemented to be used in future graphene growths. …

The Biogeochemistry Of Carbon Isotopes In Local Lakes, Stephen Edward Sadurski

Browse all Theses and Dissertations

Photosynthesis, respiration, and decay of organic matter all involve the transfer of carbon among the carbon-bearing species in the systems. These biogeochemical processes also fractionate the carbon isotope composition, which results in changes to the carbon isotope composition of the dissolved inorganic carbon (DIC) pool. This thesis presents two separate, but related studies regarding the influence of biogeochemical processes on carbon isotopes in local lakes. Crystal Lake is a small but deep glacial lake (12.5 acres, 11.9 meters). The study shows that during thermal stratification, the heaviest carbon can be found in the epilimnion near the surface, where photosynthesis dominates …

Implications Of Decade Time Scale Arctic Plant Community Change On Ecosystem Function, Mark Jason Lara

Open Access Theses & Dissertations

Almost half the global soil organic carbon pool is found in northern high latitudes. The majority of this soil carbon is stored in a greenhouse inert state within permafrost. As pronounced warming of high northern latitudes ensues, there is a strong likelihood that this substantial soil organic carbon pool will be mobilized to the atmosphere where it is likely to positively enhance greenhouse warming. Modeling studies suggest this positive feedback could alter future climate states of the Arctic and the globe, and affect how humans may need to adapt to climate change. Accordingly, understanding the patterns and controls and the …

Linking Nitrogen Biogeochemistry To Different Stages Of Wetland Soil Development In The Mississippi River Delta, Louisiana, Kelly Marie Henry

LSU Doctoral Dissertations

Extensive wetland loss and nutrient-enhanced eutrophication occur across the Mississippi River delta and include newly emergent landscapes, in the early stages of ecological succession, and older landscape formations, with fully developed ecological communities. Here I tested how the anthropogenic effects of a climate-induced vegetation shift, an oil spill, and nitrate-enrichment regulate the principal environmental factors controlling nutrient biogeochemistry in wetland soils at different stages of development throughout the Mississippi River delta. In the older, transgressing Barataria basin, there was no clear effect of the climate-induced species shift from Spartina alterniflora Loisel to Avicennia germinans L. on soil nutrient chemistry. Observed …

Biomass And Mass Balance Isotope Content Of Mussel Seep Populations, Philip Martin Riekenberg

LSU Master's Theses

Cold seep mussels, Bathymodiolus childressi, are common cold seep constituents that form large populations at upper continental slope (500-1000 m) cold seep sites in the Northern Gulf of Mexico. These mussels utilize methane present through symbiotic relationships with methanotrophic bacteria. This study uses a coupled isotope technique to determine the relative incorporation of respiratory carbon in the shell as a measure of the availability of methane between different seep sites. This method indicates a higher abundance of methane at the Brine Pool site than at the Bush Hill site which appears significantly more resource limited and that changes in methane …

Variability In Hydrology And Ecosystem Properties And Their Role In Regulating Soil Organic Matter Stability In Wetlands Of West-Central Florida, Sharon Jean Feit

USF Tampa Graduate Theses and Dissertations

Soil organic matter (SOM) provides many ecosystem services that are necessary for continued ecosystem function. The accumulation of SOM in an ecosystem is a function of its persistence time which can range from days to thousands of years. Ecosystem properties including dominant vegetation type, soil texture, and soil moisture in various habitats can regulate the persistence time of SOM.

Wetlands, because of their associated ecosystem properties, promote SOM accumulation, but little has been done to determine the ecosystem properties that regulate its persistence over time. In west-central Florida, urbanization and increased water demands have suppressed water tables in isolated wetland …

Development Of Interatomic Potentials For Large Scale Molecular Dynamics Simulations Of Carbon Materials Under Extreme Conditions, Romain Perriot

USF Tampa Graduate Theses and Dissertations

The goal of this PhD research project is to devise a robust interatomic potential for large scale molecular dynamics simulations of carbon materials under extreme conditions. This screened-environment dependent reactive empirical bond order potential (SED-REBO) is specifically designed to describe carbon materials under extreme compressive or tensile stresses. Based on the original REBO potential by Brenner and co workers, SED-REBO includes reparametrized pairwise interaction terms and a new screening term, which serves the role of a variable cutoff. The SED-REBO potential overcomes the deficiencies found with the most commonly used interatomic potentials for carbon: the appearance of artificial forces due …

Nitrogen And Carbon Export To The Gulf Of Mexico By The Atchafalaya River, A Major Distributary Of The Mississippi River, April Elizabeth Bryantmason

LSU Doctoral Dissertations

Summer hypoxia in the Northern Gulf of Mexico has been attributed to large nutrient inputs, especially nitrate-nitrogen, from the Mississippi-Atchafalaya River system. The 2008 Gulf Hypoxia Action Plan calls for river corridor wetland restoration to reduce nitrate loads, but it is largely unknown how effective riverine wetland systems in the lower Mississippi River (MR) are for nitrate removal. This dissertation research examined nitrate and carbon export from the Atchafalaya River (AR) to: (1) determine nitrate processing by a river swamp basin under varied seasons, (2) investigate nitrate retention and processing in the AR during a major flood event, and (3) …