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Articles 12001 - 12030 of 17800
Full-Text Articles in Entire DC Network
Short-Term Effect Of Simulated Salt Marsh Restoration By Sand-Amendment On Sediment Bacterial Communities, François Thomas, James T. Morris, Cathleen Wigand, Stefan M. Sievert
Short-Term Effect Of Simulated Salt Marsh Restoration By Sand-Amendment On Sediment Bacterial Communities, François Thomas, James T. Morris, Cathleen Wigand, Stefan M. Sievert
Faculty Publications
Coastal climate adaptation strategies are needed to build salt marsh resiliency and maintain critical ecosystem services in response to impacts caused by climate change. Although resident microbial communities perform crucial biogeochemical cycles for salt marsh functioning, their response to restoration practices is still understudied. One promising restoration strategy is the placement of sand or sediment onto the marsh platform to increase marsh resiliency. A previous study examined the above- and below-ground structure, soil carbon dioxide emissions, and pore water constituents in Spartina alterniflora-vegetated natural marsh sediments and sand-amended sediments at varying inundation regimes. Here, we analyzed samples from the …
Tree-Ring Reconstructions Of Streamflow For The Tennessee Valley, Sallyrose Anderson, Ross Ogle, Glenn Tootle, Abdoul Oubeidillah
Tree-Ring Reconstructions Of Streamflow For The Tennessee Valley, Sallyrose Anderson, Ross Ogle, Glenn Tootle, Abdoul Oubeidillah
Civil Engineering Faculty Publications
This study reports the preliminary results from a statistical screening of tree-ring width records from the International Tree-Ring Data Bank (ITRDB), to evaluate the strength of the hydrological signal, in dendrochronological records from the Tennessee Valley. We used United States Geological Survey (USGS) streamflow data from 11 gages, within the Tennessee Valley, and regional tree-ring chronologies, to analyze the dendroclimatic potential of the region, and create seasonal flow reconstructions. Prescreening methods included correlation, date, and temporal stability analysis of predictors to ensure practical and reliable reconstructions. Seasonal correlation analysis revealed that large numbers of regional tree-ring chronologies were significantly correlated …
Agricultural Intensification And Urbanization Negatively Impact Soil Nematode Richness And Abundance: A Meta-Analysis, Satyendra K. Pothula, Parwinder Grewal, Robert M. Auge, Arnold M. Saxton, Ernest C. Bernard
Agricultural Intensification And Urbanization Negatively Impact Soil Nematode Richness And Abundance: A Meta-Analysis, Satyendra K. Pothula, Parwinder Grewal, Robert M. Auge, Arnold M. Saxton, Ernest C. Bernard
School of Earth, Environmental, & Marine Sciences Faculty Publications
Human activity has extensively transformed the land surface by agricultural intensification and urbanization. In soil, nematodes are the most abundant invertebrates. The effect of human interventions was assessed on overall richness, overall abundance, richness and abundance of nematodes of each trophic group and colonizer-persister (c-p) guild by comparing urban, agriculture and disturbed grassland (DGL) with natural grassland (NGL) and forest ecosystems. Meta-analyses were conducted to generate quantitative summaries from 111 published articles that met the inclusion criteria, 91 expressed data in grams and 20 expressed data in cm3. Results from data expressed per 100 g of soil indicated that overall …
Gamete Nuclear Migration In Animals And Plants, Umma Fatema, Mohammad F. Ali, Zheng Hu, Anthony J. Clark, Tomokazu Kawashima
Gamete Nuclear Migration In Animals And Plants, Umma Fatema, Mohammad F. Ali, Zheng Hu, Anthony J. Clark, Tomokazu Kawashima
Plant and Soil Sciences Faculty Publications
The migration of male and female gamete nuclei to each other in the fertilized egg is a prerequisite for the blending of genetic materials and the initiation of the next generation. Interestingly, many differences have been found in the mechanism of gamete nuclear movement among animals and plants. Female to male gamete nuclear movement in animals and brown algae relies on microtubules. By contrast, in flowering plants, the male gamete nucleus is carried to the female gamete nucleus by the filamentous actin cytoskeleton. As techniques have developed from light, electron, fluorescence, immunofluorescence, and confocal microscopy to live-cell time-lapse imaging using …
Responses Of Soil Carbon Sequestration To Climate-Smart Agriculture Practices: A Meta-Analysis, Xiongxiong Bai, Yawen Huang, Wei Ren, Mark Coyne, Pierre-Andre Jacinthe, Bo Tao, Dafeng Hui, Jian Yang, Chris Matocha
Responses Of Soil Carbon Sequestration To Climate-Smart Agriculture Practices: A Meta-Analysis, Xiongxiong Bai, Yawen Huang, Wei Ren, Mark Coyne, Pierre-Andre Jacinthe, Bo Tao, Dafeng Hui, Jian Yang, Chris Matocha
Biology Faculty Research
Climate-smart agriculture (CSA) management practices (e.g., conservation tillage, cover crops, and biochar applications) have been widely adopted to enhance soil organic carbon (SOC) sequestration and to reduce greenhouse gas emissions while ensuring crop productivity. However, current measurements regarding the influences of CSA management practices on SOC sequestration diverge widely, making it difficult to derive conclusions about individual and combined CSA management effects and bringing large uncertainties in quantifying the potential of the agricultural sector to mitigate climate change. We conducted a meta-analysis of 3,049 paired measurements from 417 peer-reviewed articles to examine the effects of three common CSA management practices …
Trans-Cinnamic Acid-Induced Leaf Expansion Involves An Auxin-Independent Component, Jasmina Kurepa, Jan A. Smalle
Trans-Cinnamic Acid-Induced Leaf Expansion Involves An Auxin-Independent Component, Jasmina Kurepa, Jan A. Smalle
Plant and Soil Sciences Faculty Publications
The phenylpropanoid pathway, the source of a large array of compounds with diverse functions, starts with the synthesis of trans-cinnamic acid (t-CA) that is converted by cinnamate-4-hydroxylase (C4H) into p-coumaric acid. We have recently shown that in Arabidopsis, exogenous t-CA promotes leaf growth by increasing cell expansion and that this response requires auxin signaling. We have also shown that cell expansion is increased in C4H loss-of-function mutants. Here we provide further evidence that leaf growth is enhanced by either t-CA or a t-CA derivative that accumulates upstream of C4H. We also show that …
An Underground Radio Wave Propagation Prediction Model For Digital Agriculture, Abdul Salam
An Underground Radio Wave Propagation Prediction Model For Digital Agriculture, Abdul Salam
Faculty Publications
Underground sensing and propagation of Signals in the Soil (SitS) medium is an electromagnetic issue. The path loss prediction with higher accuracy is an open research subject in digital agriculture monitoring applications for sensing and communications. The statistical data are predominantly derived from site-specific empirical measurements, which is considered an impediment to universal application. Nevertheless, in the existing literature, statistical approaches have been applied to the SitS channel modeling, where impulse response analysis and the Friis open space transmission formula are employed as the channel modeling tool in different soil types under varying soil moisture conditions at diverse communication distances …
Capture Zone Analysis Of A Wellfield To Assess Contaminant Transport, Prince Kojo Oware
Capture Zone Analysis Of A Wellfield To Assess Contaminant Transport, Prince Kojo Oware
Theses and Dissertations
Radium is a common contaminant to the deep Cambrian- Ordovician aquifer in northern Illinois. Deep groundwater aquifers are used as fresh water resource in many parts of the world. Due to overuse, increase in salinity, natural and human-driven contamination, sustainability of these aquifer systems is uncertain. The purpose of this study is to better understand the groundwater flow system in deep bedrock aquifers in northern Illinois, and its control on the radium contamination in Rochelle’s Public Water Supply Wells (PWSW). We have tested two hypotheses: (1) the Radium (Ra) transport is driven by large pumping centers that interrupt groundwater flow …
Evaluating A New Algorithm For Satellite-Based Evapotranspiration For North American Ecosystems: Model Development And Validation, Bassil El Masri, Abdullah F. Rahman, Danilo Dragoni
Evaluating A New Algorithm For Satellite-Based Evapotranspiration For North American Ecosystems: Model Development And Validation, Bassil El Masri, Abdullah F. Rahman, Danilo Dragoni
School of Earth, Environmental, & Marine Sciences Faculty Publications
Highlights
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We developed an algorithm to estimate evapotranspiration based solely on satellite data.
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Our model is able to track the seasonal changes in the flux tower observations.
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The errors in the model ET output were lower than the MODIS ET product.
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The modeled and observed ET strong relationship implies that our model has the potential to be applied to different ecosystems.
Abstract
We introduce a different operational approach to estimate 8-day average daily evapotranspiration (ET) using both routinely available data and the Penman-Monteith (P-M) equation for canopy transpiration and evaporation of intercepted water and Priestley and Taylor for soil evaporation. …
Growth, Condition, And Trophic Relations Of Stocked Trout In Southern Appalachian Mountain Streams, Jesse R. Fischer, Thomas J. Kwak, H. Jared Flowers, W. Gregory Cope, Jacob M. Rash, Douglas A. Besler
Growth, Condition, And Trophic Relations Of Stocked Trout In Southern Appalachian Mountain Streams, Jesse R. Fischer, Thomas J. Kwak, H. Jared Flowers, W. Gregory Cope, Jacob M. Rash, Douglas A. Besler
United States Geological Survey: Staff Publications
Stream trout fisheries are among the most popular and valuable in the United States, but many are dependent on hatcheries to sustain fishing and harvest. Thus, understanding the ecology of hatchery‐reared trout stocked in natural environments is fundamental to management. We evaluated the growth, condition, and trophic relations of Brook Trout Salvelinus fontinalis, Brown Trout Salmo trutta, and Rainbow Trout Oncorhynchus mykiss that were stocked in southern Appalachian Mountain streams in western North Carolina. Stocked and wild (naturalized) trout were sampled over time (monthly; September 2012–June 2013) to compare condition and diet composition and to evaluate temporal dynamics of trophic …
Vaquita Face Extinction From Bycatch. Comment On Manjarrez-Bringas, N. Et Al., Lessons For Sustainable Development: Marine Mammal Conservation Policies And Its Social And Economic Effects., Karl W. Flessa, Luis Calderon-Aguilera, Carlos E. Cintra-Buenrostro, David L. Dettman, Gregory P. Dietl, David H. Goodwin, David K. Jacobs, Michal Kowalewski, Steven M. Nelson, Kirsten Rowell, Bernard R. Schone, Jansen A. Smith, Francisco Zamora-Arroyo
Vaquita Face Extinction From Bycatch. Comment On Manjarrez-Bringas, N. Et Al., Lessons For Sustainable Development: Marine Mammal Conservation Policies And Its Social And Economic Effects., Karl W. Flessa, Luis Calderon-Aguilera, Carlos E. Cintra-Buenrostro, David L. Dettman, Gregory P. Dietl, David H. Goodwin, David K. Jacobs, Michal Kowalewski, Steven M. Nelson, Kirsten Rowell, Bernard R. Schone, Jansen A. Smith, Francisco Zamora-Arroyo
School of Earth, Environmental, & Marine Sciences Faculty Publications
We are among the scientists who have documented the environmental and ecological changes to the Upper Gulf of California following the reduction in the Colorado River’s flow. We object to any suggestion that our research supports Manjarrez-Bringas et al.’s conclusion that the decline in the Colorado River’s flow is the reason for the decline in the population of the endangered vaquita porpoise (Phocoena sinus). Manjarrez-Bringas et al.’s conclusions are incongruent with their own data, their logic is untenable, their analyses fail to consider current illegal fishing practices, and their recommendations are unjustified and misdirected. Vaquita face extinction because of bycatch, …
Notes And Discussion Piece: Status Of The Topeka Shiner In Iowa, Clay L. Pierce, Nicholas T. Simpson, Alexander P. Bybel, Courtney L. Zambory, Michael J. Weber, Kevin J. Roe
Notes And Discussion Piece: Status Of The Topeka Shiner In Iowa, Clay L. Pierce, Nicholas T. Simpson, Alexander P. Bybel, Courtney L. Zambory, Michael J. Weber, Kevin J. Roe
United States Geological Survey: Staff Publications
The Topeka shiner Notropis topeka is native to Iowa, Kansas, Minnesota, Missouri, Nebraska, and South Dakota and has been federally listed as endangered since 1998. Our goals were to determine the present distribution and qualitative status of Topeka shiners throughout its current range in Iowa and characterize the extent of decline in relation to its historic distribution. We compared the current (2016–2017) distribution to distributions portrayed in three earlier time periods. In 2016–2017 Topeka shiners were found in 12 of 20 HUC10 watersheds where they occurred historically. Their status was classified as stable in 21% of the HUC10 watersheds, possibly …
Hemp Research Underway At Utah State University, Utah Water Research Laboratory
Hemp Research Underway At Utah State University, Utah Water Research Laboratory
News
Scientists at Utah State University are studying cultivation practices to optimize the yield and quality of hemp for botanical medicines.
Index
Bulletin of the University of Nebraska State Museum (1924–2023)
No abstract provided.
Characteristics Of Soils Under Common Management Practices On Farms In Western Kentucky, River Dowell
Characteristics Of Soils Under Common Management Practices On Farms In Western Kentucky, River Dowell
Scholars Week
Characteristics of Soils under Common Management Practices
on Farms in Western Kentucky
River O. Dowell and Iin P. Handayani, Murray State University, Kentucky
ABSTRACT
Properly understanding the importance of soil properties and how they continuously change is a key to achieving sustainability in agriculture. This study was conducted to observe the changes of soil properties regarding common tillage systems in Kentucky. Undisturbed and disturbed soil samples were collected from Butler County, KY at depths of 0-7.5 cm and 7.5-15 cm from four sites representing the different management practices of conventional tillage, no-till, pasture, and woodlands. The samples were analyzed for …
Delineation Of Ohio River Flood Zones In Ballard County Using Remote Sensing, Nathan Rister
Delineation Of Ohio River Flood Zones In Ballard County Using Remote Sensing, Nathan Rister
Scholars Week
The purpose of this study was to use remote sensing to map flood zones in Ballard County as it correlates to the Ohio River flood gauges. This will help Wildlife managers to know which areas are most likely to be flooded by simply looking at river gauges and prevent them to having to check which areas are flooded in person. By using this technique wildlife managers will be able to save time and resources as well as better manage wildlife areas along the Ohio River.
Documenting Evolution: Comparing And Contrasting Late Mesozoic And Late Cenozoic Molluscan Patterns, Joshua Slattery
Documenting Evolution: Comparing And Contrasting Late Mesozoic And Late Cenozoic Molluscan Patterns, Joshua Slattery
USF Tampa Graduate Theses and Dissertations
Despite major advances, evolutionary theory still has numerous shortcomings in terms of fully understanding the controls on speciation and diversification. A major factor limiting our knowledge is how biology and paleobiology view speciation from separate micro- and macro-evolutionary perspectives, respectively. Biologists typically examine microevolutionary changes within species from various biogeographic, behavioral, morphological, and genetic perspectives, which contrasts to the macroevolutionary approach of most paleobiologists, who have examined the same phenomena at larger scales but with the standpoint of time, have also concentrated on aspects of global or regional diversification (e.g., richness, origination rates, and extinction rates) over the long-term. Noticeably …
Chemical Amendments Of Dryland Saline–Sodic Soils Did Not Enhance Productivity And Soil Health In Fields Without Effective Drainage, Girma A. Birru, David E. Clay, Thomas M. Desutter, Cheryl L. Reese, Ann C. Kennedy, Sharon A. Clay, Stephanie A. Bruggeman, Rachel K. Owen, Douglas D. Malo
Chemical Amendments Of Dryland Saline–Sodic Soils Did Not Enhance Productivity And Soil Health In Fields Without Effective Drainage, Girma A. Birru, David E. Clay, Thomas M. Desutter, Cheryl L. Reese, Ann C. Kennedy, Sharon A. Clay, Stephanie A. Bruggeman, Rachel K. Owen, Douglas D. Malo
Agronomy, Horticulture and Plant Science Faculty Publications
A common restoration treatment for saline–sodic soils involves improving soil drainage, applying soil amendments (e.g., CaSO4, CaCl2, or elemental S), and leaching with water that has a relatively low electrical conductivity. However, due to high subsoil bulk densities and low drainable porosities, these treatments many not be effective in glaciated dryland systems. A 3-yr field study conducted in three model systems determined the impact of chemical amendments (none, CaCl2, CaSO4, and elemental S) on plant growth, microbial composition, temporal changes in electrical conductivity (ECe ), and the relative sodium content (%Na). …
Coupling Metaproteomics With Taxonomy To Determine Responses Of Bacterioplankton To Organic Perturbations In The Western Arctic Ocean, Molly P. Mikan
Coupling Metaproteomics With Taxonomy To Determine Responses Of Bacterioplankton To Organic Perturbations In The Western Arctic Ocean, Molly P. Mikan
OES Theses and Dissertations
Understanding how the functionality of marine microbial communities change over time and space, and which taxonomic groups dominate distinct metabolic pathways, are essential to understanding the ecology of these microbiomes and the factors contributing to their regulation of elemental cycles in the oceans. The primary goal of this dissertation was to investigate the community metabolic and taxonomic responses and the degradation potential of two compositionally distinct marine microbiomes within the shallow shelf ecosystem of the Chukchi Sea after rapid fluctuations in algal organic matter availability. Novel bioinformatics tools were collaboratively developed and used together with community proteomics (metaproteomics) to characterize …
Permeability Prediction In Rocks Experiencing Mineral Precipitation And Dissolution: A Numerical Study, Qifei Niu, Chi Zhang
Permeability Prediction In Rocks Experiencing Mineral Precipitation And Dissolution: A Numerical Study, Qifei Niu, Chi Zhang
Geosciences Faculty Publications and Presentations
In this study, we focus on the electrical tortuosity-based permeability model k = reff2/8F (reff is an effective pore size, and F is the formation factor) and analyze its applicability to rocks experiencing mineral precipitation and dissolution. Two limiting cases of advection-dominated water-rock reactions are simulated, that is, the reaction-limited and transport-limited cases. At the pore scale, the two precipitation/dissolution patterns are simulated with a geometrical model and a phenomenological model. The fluid and electric flows in the rocks are simulated by directly solving the linear Stokes equation and Laplace equation on the representative …
Regenerative Grazing And The Benefits Of Livestock On Soils In Northern New South Wales, Raymond Mooney
Regenerative Grazing And The Benefits Of Livestock On Soils In Northern New South Wales, Raymond Mooney
Independent Study Project (ISP) Collection
Conventional cattle grazing has received criticism for environmental degradation in the past. Regenerative grazing and the principles of regenerative agriculture show encouraging signs that proper livestock management and planned grazing can reverse degradation and mitigate climate change. An emphasis on soil health and increasing soil carbon and organic matter levels reveals positive feedback for environmental health, the economic security of farmers, and nutritional health of consumers.
In this study I looked to investigate the benefits of regenerative agriculture, reasons why it is being practiced, and the extent it is practiced within the grazing in comparison to traditional methods within Northern …
Differentiation Of Surface Water And Groundwater In A Karst System Using Anthropogenic Signatures, Joe Honings
Differentiation Of Surface Water And Groundwater In A Karst System Using Anthropogenic Signatures, Joe Honings
Faculty Publications
Surface water-groundwater interaction within a karstic system enhances contaminant transport, making karst aquifers susceptible to anthropogenic practices. Contaminated waters related to agricultural and animal husbandry in northwestern Illinois (USA) prompted this investigation. Six streams and five springs were sampled for 16 parameters to assess anthropogenic influences. Statistical analyses revealed differences in 13 of 16 parameters between the stream and spring waters. Rock-water interaction was identified as the dominant mechanism defining the chemistry for both waters, which were classified as Ca-Mg HCO3. Elevated nitrate as nitrogen (NO3-N), chloride (Cl-), sodium, and potassium concentrations indicate that human activities have influenced the quality …
Dissolved Inorganic Nitrogen Dynamics In Swash Zone Sands Of Long Bay, Sc, Alexis F. Echols
Dissolved Inorganic Nitrogen Dynamics In Swash Zone Sands Of Long Bay, Sc, Alexis F. Echols
Honors Theses
A key component affecting the biogeochemistry of the sedimentary environment is pore water between grains of sediments. Sedimentary microorganisms are constantly modifying chemical compounds as part of their life functions which are then exchanged between the sediment column and the overlying water column. Dissolved inorganic nitrogen, a major element for life, takes on several forms including nitrate, nitrite, and ammonium which vary in concentration throughout the sediment and with respect to each other. The relative concentrations of these nitrogen species have been previously briefly explored in sandy columns, where redox gradients that control their relative concentrations can be fairly deep …
Defining, Measuring, And Applying Soil Quality: An Unresolved Debate, Salvador Ramirez Ii
Defining, Measuring, And Applying Soil Quality: An Unresolved Debate, Salvador Ramirez Ii
Doctor of Plant Health Program: Dissertations and Student Research
Paradigm shifts occur periodically in the sciences. Proposed paradigm shifts offer opportunities to reexamine extant paradigms and evaluate new ones. Soil science experienced a controversy resembling a proposed paradigm shift in the late 1990s and early 2000s when it grappled with the idea of soil quality (SQ). The most contentious points in the SQ debates were (1) the word “quality” itself and designing a functional definition, (2) identifying appropriate soil quality indicators, (3) the integration of soil quality indicators, and (4) the interpretation of soil quality indicators. The latter three disagreements were rooted in the established, fundamental, soil science paradigm. …
Character And Water Quality Of Sandpiper Pond: A Coastal Pond Assessment, Fifteen Years After Restoration, Nicholas E. Workman
Character And Water Quality Of Sandpiper Pond: A Coastal Pond Assessment, Fifteen Years After Restoration, Nicholas E. Workman
Honors Theses
Sandpiper Pond is a coastal pond at Huntington Beach State Park, South Carolina. Originally a tidal inlet surrounded by marshland, it was isolated in 1989 and rechanneled in 2004-2005 under a community-based wetland restoration project. The project was designed to restore the pond to a tidal inlet to improve water quality and biodiversity. Since then, the tidal connection with the ocean has been severed once more and the main influx of seawater occurs from the marsh during spring high tides. In this three-month study, the current state of Sandpiper Pond is evaluated using fundamental biogeochemical indicators that are indicative of …
Spatiotemporal Variation Of Benthic Silica Fluxes In The Ngom Shelf, Byron Ebner
Spatiotemporal Variation Of Benthic Silica Fluxes In The Ngom Shelf, Byron Ebner
LSU Master's Theses
Dissolved silica (DSi), plays an important role in regulating primary productivity of silicifying organisms, such as diatoms which precipitate hard parts composed of biogenic silica (bSi) in coastal and shelf ecosystems fed by major rivers. In the Northern Gulf of Mexico (NGOM), loading of nitrogen and phosphorous have increased compared to a decline in DSi in the Mississippi River. Continued decreasing in DSi loading could lead to limited diatom growth and production or shifts in community composition, therefore, it is important understand the role of benthic fluxes in providing silica to the overlying water column as there are few regional …
Depositional Facies And Sequence Stratigraphic Model For The Silurian Reefs, Michigan Basin, Usa, Zaid N. Nadhim
Depositional Facies And Sequence Stratigraphic Model For The Silurian Reefs, Michigan Basin, Usa, Zaid N. Nadhim
Masters Theses
Depositional models for the Silurian reefs in the Michigan Basin suggest that internal facies are either (i) randomly distributed within a symmetrical reef structure, or (ii) highly asymmetrical and strongly controlled by paleo-wind direction. To further test the applicability of these models, internal facies distributions were mapped using high-resolution core and log data in two sets of Silurian reefs. The results suggest that the relationship between reef geometry, facies distribution and proposed paleo-wind direction is more inconsistent than recently proposed. More specifically, facies descriptions from the Silurian reefs suggest the following. First, overall reef geometry and facies distributions are not …
Nitrate Contaminant Tracing In Surface And Groundwater In The Great Miami River Watershed: Environmental Isotope Approach, Rachel Kristine Buzeta
Nitrate Contaminant Tracing In Surface And Groundwater In The Great Miami River Watershed: Environmental Isotope Approach, Rachel Kristine Buzeta
Honors Theses
The global population has increased exponentially causing several challenges surrounding sustainability, including greater food production needs. To meet these demands and boost agricultural productivity, more efficient practices and fertilizers are used. Synthetic fertilizers and other nutrient sources have resulted in water quality degradation and pollution. Much of the Great Miami River Watershed’s streams and aquifers in southwestern Ohio are affected by nitrate contaminants originating from anthropogenic sources including synthetic and organic fertilizer used for agriculture, human wastes (domestic, industrial, and municipal wastes), and urbanization. High nitrate concentrations cause ecological disturbances across all trophic levels. Nitrate levels greater than 10 mg/L …
Endolithic Microbial Carbon Cycling In East Antarctica, Natalie Tyler
Endolithic Microbial Carbon Cycling In East Antarctica, Natalie Tyler
Theses and Dissertations
Microbes adapt to inhospitable conditions by colonizing niches that protect them from severe environmental conditions, making them model organisms in the search for life on other planets. Endoliths are globally ubiquitous microbes that colonize structural cavities within rocks, which protect them from environmental stressors while maintaining access to nutrition and light sources. Despite harsh katabatic winds, extreme temperature fluctuations, harmful UV radiation and exposure to desiccation, endolithic communities have been observed in Antarctica. Previous studies have found viable and abundant microbial biomass through microscopy and the addition of isotopic labels. However, due to the slow metabolic activity of these microbes, …
Submarine Groundwater Discharge In The Southern Chesapeake Bay: Constraints From Numerical Models, Charles Louis Carlson
Submarine Groundwater Discharge In The Southern Chesapeake Bay: Constraints From Numerical Models, Charles Louis Carlson
OES Theses and Dissertations
Terrestrial and oceanic forces drive fluid flow within the coastal zone to produce submarine groundwater discharge (SGD). Groundwater flowing from the seabed serves as a significant pathway for contaminants and nutrients, producing an active biogeochemical reaction zone. In order to quantify the importance of SGD in geochemical and hydrologic budgets for the lower Chesapeake Bay, three coastal Virginia transects (southern Eastern Shore, Lafayette River, and Ocean View beach) with different topographic gradients were modeled using similar boundary conditions and consistent treatment of hydrogeologic layers. A sensitivity study was performed on the variables of recharge rate, seawater density, and hydraulic permeability. …