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Articles 13981 - 14010 of 17793
Full-Text Articles in Entire DC Network
Characterization, Diagenesis, And Geocellular Modeling Of Winnipegosis Formation Pinnacle Reefs In The Williston Basin, North Dakota, Nicholas W. Bosshart
Characterization, Diagenesis, And Geocellular Modeling Of Winnipegosis Formation Pinnacle Reefs In The Williston Basin, North Dakota, Nicholas W. Bosshart
Theses and Dissertations
The Middle Devonian Winnipegosis Formation of the North Dakota Williston Basin contains pinnacle reef structures which have been targeted in the past for hydrocarbon production. These reefs have not been proven to hold economically important primary recoverable reserves, and are now being analyzed for potential CO₂ EOR and storage applications.
During this study multiple sizes of Winnipegosis Formation pinnacle reef geocellular models were constructed utilizing data from North Dakota Winnipegosis pinnacle reefs wells, cores, and thin sections. These models were then simulated for CO₂ injectivity.
Initial results show that Winnipegosis pinnacle reefs smaller than 1.5 miles in diameter are likely …
Destruction Of Chlorinated Hydrocarbons By Zero-Valent Zinc And Bimetallic Zinc Reductants In Bench-Scale Investigations, Christopher Scott Cushman
Destruction Of Chlorinated Hydrocarbons By Zero-Valent Zinc And Bimetallic Zinc Reductants In Bench-Scale Investigations, Christopher Scott Cushman
Browse all Theses and Dissertations
Many remediation technologies have been developed to treat extensive subsurface contamination by chlorinated hydrocarbons (CHCs). One such technology is a permeable reactive barrier (PRB), which contains reactive media that acts as an electron donor in order to reduce CHCs. Extensive effort has been placed on finding the most suitable reactive media in PRBs, with zero-valent iron (ZVI) being the most commonly utilized media. However, zero-valent zinc (ZVZ) is a promising replacement for ZVI in PRBs as it will more readily donate electrons, resulting in more rapid degradation of CHCs. In addition, amending a secondary/catalytic metal to primary metal surface can …
Biogeochemistry Of Sulfur Isotopes In Crystal Lake, Clark County, West-Central Ohio, Amanda Lynn Meyer
Biogeochemistry Of Sulfur Isotopes In Crystal Lake, Clark County, West-Central Ohio, Amanda Lynn Meyer
Browse all Theses and Dissertations
Crystal Lake showed distinct biogeochemical patterns, which were governed by thermal stratification, photosynthesis, and sulfur redox processes. Field parameter measurements and water and Planktothrix rubescens samples were collected in May, August, and October, 2013 at the deepest point in the lake, to better understand these processes. At the metalimnion-hypolimnion boundary, P. rubescens produced chlorophyll and turbidity maxima. Photosynthesis produced oxygen-rich and nutrient-poor surface waters. The decay of organic matter produced anoxic, nutrient-rich water in the hypolimnion. Sulfate concentrations were high in the epilimnion and metalimnion, with a maximum at the layer of P. rubescens, and decreased with depth in the …
Mercury Distributions And Cycling In The North Atlantic And Eastern Tropical Pacific Oceans, Katlin L. Bowman
Mercury Distributions And Cycling In The North Atlantic And Eastern Tropical Pacific Oceans, Katlin L. Bowman
Browse all Theses and Dissertations
The distribution of mercury (Hg) in the ocean is complex as a result of in situ chemical transformations and inputs from natural and anthropogenic sources. Within the ocean, inorganic Hg is methylated to monomethylmercury (MMHg), which bioaccumulates and biomagnifies in marine food webs and poses a health risk to humans who eat fish. The biogeochemistry of Hg in the ocean has been studied for decades, however, recently improved sampling and analytical techniques have allowed for an enhanced understanding of global distributions of different Hg species. This dissertation uses a newly developed method for the analysis of MMHg that improves detection …
Environmental Factors Affecting Methylmercury In Fish Of The Laurentian Great Lakes Region, Joel Harvey
Environmental Factors Affecting Methylmercury In Fish Of The Laurentian Great Lakes Region, Joel Harvey
Browse all Theses and Dissertations
Monomethylmercury (MMHg) can accumulate in fish to concentrations that pose a threat to the health of fish, piscivorous organisms, and humans who eat fish. A variety of environmental factors have been hypothesized to influence either the methylation of inorganic Hg or the bioaccumulation and magnification of MMHg. This study investigates the influence of selected environmental factors on MMHg concentrations in freshwater fish across a regional scale, most of the U.S. portion of Laurentian Great Lakes region. Fish MMHg was correlated with proton deposition, sulfate deposition, nitrate deposition, mercury deposition, pH, watershed area, and Secchi depth. Only proton deposition was positively …
Architecture, Heterogeneity, And Origin Of Late Miocene Fluvial Deposits Hosting The Most Important Aquifer In The Great Plains, Usa, R. Matthew Joeckel, Steve R. Wooden Jr., Jesse T. Korus, Jon Garbisch
Architecture, Heterogeneity, And Origin Of Late Miocene Fluvial Deposits Hosting The Most Important Aquifer In The Great Plains, Usa, R. Matthew Joeckel, Steve R. Wooden Jr., Jesse T. Korus, Jon Garbisch
Department of Earth and Atmospheric Sciences: Faculty Publications
The Ash Hollow Formation (AHF) of the Ogallala Group is an important sedimentary archive of the emergence of the Great Plains and it contains major groundwater resources. Stratal patterns of constituent alluvial lithofacies demonstrate that the AHF is much more heterogeneous than is commonly assumed. Very fine- to fine-grained sandstone dominate overall, chiefly lithofacies Sm (massive to locally stratified sandstone). Stacked, thin sheets of Sm with accretionary macroform surfaces are common, indicating that many sandstone architectural elements originated as compound-bar deposits in dominantly sand-bed streams. Channel forms are difficult to identify and steep cutbanks are absent. Multiple units of lithofacies …
A 60,000-Year Record Of Hydrologic Variability In The Central Andes From The Hydrogen Isotopic Composition Of Leaf Waxes In Lake Titicaca Sediments, Kyrstin L. Fornace, Konrad A. Hughen, Timothy M. Shanahan, Sherilyn C. Fritz, Paul A. Baker, Sean P. Sylva
A 60,000-Year Record Of Hydrologic Variability In The Central Andes From The Hydrogen Isotopic Composition Of Leaf Waxes In Lake Titicaca Sediments, Kyrstin L. Fornace, Konrad A. Hughen, Timothy M. Shanahan, Sherilyn C. Fritz, Paul A. Baker, Sean P. Sylva
Department of Earth and Atmospheric Sciences: Faculty Publications
A record of the hydrogen isotopic composition of terrestrial leaf waxes (δDwax) in sediment cores from Lake Titicaca provides new insight into the precipitation history of the Central Andes and controls of South American Summer Monsoon (SASM) variability since the last glacial period. Comparison of the δDwax record with a 19-kyr δD record from the nearby Illimani ice core supports the interpretation that precipitation δD is the primary control on δDwax with a lesser but significant role for local evapotranspiration and other secondary influences on δDwax. The Titicaca δDwax record con-firms overall wetter conditions in the Central Andes during the …
Analysis Of A Sponge Bioherm From The Hermosa Group, Molas Lake Area, Colorado, Joanna Hamilton
Analysis Of A Sponge Bioherm From The Hermosa Group, Molas Lake Area, Colorado, Joanna Hamilton
Honors Projects
The Hermosa Group is a Pennsylvanian (~310 Ma) rock package found in the southwestern San Juan Mountains and the Paradox Basin. The Paradox Basin was an evaporite basin in which alternating carbonate, sandstone and siltstone layers were deposited at the margins. Within the carbonate layers, ancient phylloid algal mounds and sponge bioherms can be found. In this project I document fossil sponges and algae from a Hermosa Group locality in southwestern Colorado. I look at the environments in which the sponges lived, those being relatively deep water, above wave-base; as well as inter-sponge growth habits, where one is dominant and …
Prolonged Instability Prior To A Regime Shift, Trisha L. Spanbauer, Craig R. Allen, David G. Angeler, Tarsha Eason, Sherilyn C. Fritz, Ahjond S. Garmestani, Kirsty L. Nash, Jeffrey R. Stone
Prolonged Instability Prior To A Regime Shift, Trisha L. Spanbauer, Craig R. Allen, David G. Angeler, Tarsha Eason, Sherilyn C. Fritz, Ahjond S. Garmestani, Kirsty L. Nash, Jeffrey R. Stone
Department of Earth and Atmospheric Sciences: Faculty Publications
Regime shifts are generally defined as the point of ‘abrupt’ change in the state of a system. However, a seemingly abrupt transition can be the product of a system reorganization that has been ongoing much longer than is evident in statistical analysis of a single component of the system. Using both univariate and multivariate statistical methods, we tested a longterm high-resolution paleoecological dataset with a known change in species assemblage for a regime shift. Analysis of this dataset with Fisher Information and multivariate time series modeling showed that there was a ~2000 year period of instability prior to the regime …
The Emerging Field Of Geogenomics: Constraining Geological Problems With Genetic Data, Paul A. Baker, Sherilyn C. Fritz, Christopher W. Dick, Andrew J. Eckert, Brian K. Horton, Stefano Manzoni, Camila C. Ribas, Carmala N. Garzione, David S. Battisti
The Emerging Field Of Geogenomics: Constraining Geological Problems With Genetic Data, Paul A. Baker, Sherilyn C. Fritz, Christopher W. Dick, Andrew J. Eckert, Brian K. Horton, Stefano Manzoni, Camila C. Ribas, Carmala N. Garzione, David S. Battisti
Department of Earth and Atmospheric Sciences: Faculty Publications
The development of a genomics-derived discipline within geology is timely, as a result of major advances in acquiring and processing geologically relevant genetic data. This paper articulates the emerging field of “geogenomics,” which involves the use of large-scale genetic data to constrain geological hypotheses. The paper introduces geogenomics and discusses how hypotheses can be ad-dressed through collaboration between geologists and evolutionary biologists. As an example, geogenomic methods are applied to evaluate competing hypotheses regarding the timing of the Andean uplift, the closure of the Isthmus of Panama, the onset of trans-Amazon drainage, and Quaternary climate variation in the Neotropics.
Wetland Reserve Program Enhances Site Occupancy And Species Richness In Assemblages Of Anuran Amphibians In The Mississippi Alluvial Valley, Usa, Susan C. Walls, J. Hardin Waddle, Stephen P. Faulkner
Wetland Reserve Program Enhances Site Occupancy And Species Richness In Assemblages Of Anuran Amphibians In The Mississippi Alluvial Valley, Usa, Susan C. Walls, J. Hardin Waddle, Stephen P. Faulkner
United States Geological Survey: Staff Publications
We measured amphibian habitat use to quantify the effectiveness of conservation practices implemented under the Wetland Reserve Program (WRP), an initiative of the U.S. Department of Agriculture’s Natural Resources Conservation Service. From February to June 2007, we quantified calling male anurans in cultivated cropland, former cultivated cropland restored through the WRP, and mature bottomland hardwood forest. Sites were located in two watersheds within the Mississippi Alluvial Valley of Arkansas and Louisiana, USA. We estimated detection probability and site occupancy within each land use category using a Bayesian hierarchical model of community species occurrence, and derived an estimate of species richness …
Maintaining Resilience In The Face Of Climate Change, Alejandro E. Camacho, T. Douglas Beard
Maintaining Resilience In The Face Of Climate Change, Alejandro E. Camacho, T. Douglas Beard
United States Geological Survey: Staff Publications
Climate change, when combined with more conventional stress from human exploitation, calls into question the capacity of both existing ecological communities and resource management institutions to experience disturbances while substantially retaining their same functions and identities (Zellmer and Gunderson 2009; Ruhl 2011). In other words, the physical and biological effects of climate change raise fundamental challenges to the resilience of natural ecosystems (Gunderson and Holling 2002). Perhaps more importantly, the projected scope of ecological shifts from global climate change-and uncertainty about such changes-significantly stresses the capacity of legal institutions to manage ecosystem change (Camacho 2009). Existing governmental institutions lack the …
Riverbank Filtration Potential Of Pharmaceuticals In A Wastewater-Impacted Stream, Paul M. Bradley, Larry B. Barber, Joesph W. Duris, William T. Foreman, Edward T. Furlong, Laura E. Hubbard, Kasey J. Hutchinson, Steffanie H. Keefe, Dana W. Kolpin
Riverbank Filtration Potential Of Pharmaceuticals In A Wastewater-Impacted Stream, Paul M. Bradley, Larry B. Barber, Joesph W. Duris, William T. Foreman, Edward T. Furlong, Laura E. Hubbard, Kasey J. Hutchinson, Steffanie H. Keefe, Dana W. Kolpin
United States Geological Survey: Staff Publications
Pharmaceutical contamination of shallow groundwater is a substantial concern in effluent-dominated streams, due to high aqueous mobility, designed bioactivity, and effluent-driven hydraulic gradients. In October and December 2012, effluent contributed approximately 99% and 71%, respectively, to downstream flow in Fourmile Creek, Iowa, USA. Strong hydrologic connectivity was observed between surface-water and shallow-groundwater. Carbamazepine, sulfamethoxazole, and immunologically related compounds were detected in groundwater at greater than 0.02 mg L^-1 at distances up to 6 m from the stream bank. Direct aqueous-injection HPLC-MS/MS revealed 43% and 55% of 110 total pharmaceutical analytes in surface-water samples in October and December, respectively, with 16% …
Biogeochemical Aspects Of Uranium Mineralization, Mining, Milling, And Remediation, Kate M. Campbell, Tanya J. Gallegos, Edward R. Landa
Biogeochemical Aspects Of Uranium Mineralization, Mining, Milling, And Remediation, Kate M. Campbell, Tanya J. Gallegos, Edward R. Landa
United States Geological Survey: Staff Publications
Natural uranium (U) occurs as a mixture of three radioactive isotopes: 238U, 235U, and 234U. Only 235U is fissionable and makes up about 0.7% of natural U, while 238U is overwhelmingly the most abundant at greater than 99% of the total mass of U. Prior to the 1940s, U was predominantly used as a coloring agent, and U-bearing ores were mined mainly for their radium (Ra) and/or vanadium (V) content; the bulk of the U was discarded with the tailings (Finch et al., 1972). Once nuclear fission was discovered, the economic importance of U increased greatly. The mining and milling …
Comparing Cropland Net Primary Production Estimates Frominventory, A Satellite-Based Model, And A Process-Based Model In Themidwest Of The United States, Zengpeng Li, Shuguang Liu, Zhengxi Tan, Normann B. Bliss, Claudia J. Young, Tristram O. West, Stephen M. Ogle
Comparing Cropland Net Primary Production Estimates Frominventory, A Satellite-Based Model, And A Process-Based Model In Themidwest Of The United States, Zengpeng Li, Shuguang Liu, Zhengxi Tan, Normann B. Bliss, Claudia J. Young, Tristram O. West, Stephen M. Ogle
United States Geological Survey: Staff Publications
Accurately quantifying the spatial and temporal variability of net primary production (NPP) for crop-lands is essential to understand regional cropland carbon dynamics. We compared three NPP estimates for croplands in the Midwestern United States: inventory-based estimates using crop yield data from the U.S. Department of Agriculture (USDA) National Agricultural Statistics Service (NASS); estimates from the satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) NPP product; and estimates from the General Ensemble biogeochemical Modeling System (GEMS) process-based model. The three methods estimated mean NPP in the range of 469–687 g C m−2yr−1and total NPP in the range of318–490 Tg C yr−1for croplands in …
Humic Substances Interfere With Detection Of Pathogenic Prion Protein, Christen B. Smith, Clarissa J. Booth, Tyler J. Wadzinski, Giuseppe Legname, Rick Chappell, Christopher J. Johnson, Joel A. Pedersen
Humic Substances Interfere With Detection Of Pathogenic Prion Protein, Christen B. Smith, Clarissa J. Booth, Tyler J. Wadzinski, Giuseppe Legname, Rick Chappell, Christopher J. Johnson, Joel A. Pedersen
United States Geological Survey: Staff Publications
Studies examining the persistence of prions (the etiological agent of transmissible spongiform encephalopathies) in soil require accurate quantification of pathogenic prion protein (PrPTSE) extracted from or in the presence of soil particles. Here, we demonstrate that natural organic matter (NOM) in soil impacts PrPTSE detection by immunoblotting. Methods commonly used to extract PrPTSE from soils release substantial amounts of NOM, and NOM inhibited PrPTSE immunoblot signal. The degree of immunoblot interference increased with increasing NOM concentration and decreasing NOM polarity. Humic substances affected immunoblot detection of prion protein from both deer and hamsters. We also establish that after interaction with …
Comparing Crop Land Net Primary Production Estimates From Inventory, A Satellite-Based Model, And A Process-Based Model In The Midwest Of The United States Zhengpeng, Zhengpeng Li, Shuguang Liu, Zhengxi Tan, Normann B. Bliss, Claudia J. Young, Tristram O. West, Stephen M. Ogle
Comparing Crop Land Net Primary Production Estimates From Inventory, A Satellite-Based Model, And A Process-Based Model In The Midwest Of The United States Zhengpeng, Zhengpeng Li, Shuguang Liu, Zhengxi Tan, Normann B. Bliss, Claudia J. Young, Tristram O. West, Stephen M. Ogle
United States Geological Survey: Staff Publications
Accurately quantifying the spatial and temporal variability of net primary production (NPP) for crop-lands is essential to understand regional cropland carbon dynamics. We compared three NPP estimates for croplands in the Midwestern United States: inventory-based estimates using crop yield data from the U.S. Department of Agriculture (USDA) National Agricultural Statistics Service (NASS); estimates from the satellite-based Moderate Resolution Imaging Spectro radiometer (MODIS) NPP product; and esti-mates from the General Ensemble bio geochemical Modeling System (GEMS) process-based model. The three methods estimated mean NPP in the range of 469–687 g C m−2yr−1and total NPP in the range …
Radiocarbon Dating Loess Deposits In The Mississippi Valley Using Terrestrial Gastropod Shells (Polygyridae, Helicinidae, And Discidae), Jeffrey S. Pigati, John Mcgeehin, Daniel R. Muhs, David A. Grimley, Jeffrey C. Nekola
Radiocarbon Dating Loess Deposits In The Mississippi Valley Using Terrestrial Gastropod Shells (Polygyridae, Helicinidae, And Discidae), Jeffrey S. Pigati, John Mcgeehin, Daniel R. Muhs, David A. Grimley, Jeffrey C. Nekola
United States Geological Survey: Staff Publications
Small terrestrial gastropod shells (mainly Succineidae) have been used successfully to date late Quaternary loess deposits in Alaska and the Great Plains. However, Succineidae shells are less common in loess deposits in the Mississippi Valley compared to those of the Polygyridae, Helicinidae, and Discidae families. In this study, we conducted several tests to determine whether shells of these gastropods could provide reliable ages for loess deposits in the Mississippi Valley. Our results show that most of the taxa that we investigated incorporate small amounts (1–5%) of old carbon from limestone in their shells, meaning that they should yield ages that …
Testing Metapopulation Concepts: Effects Of Patch Characteristics And Neighborhood Occupancy On The Dynamics Of An Endangered Lagomorph, Mitchell J. Eaton, Phillip T. Hughes, James E. Hines, James D. Nichols
Testing Metapopulation Concepts: Effects Of Patch Characteristics And Neighborhood Occupancy On The Dynamics Of An Endangered Lagomorph, Mitchell J. Eaton, Phillip T. Hughes, James E. Hines, James D. Nichols
United States Geological Survey: Staff Publications
Metapopulation ecology is a field that is richer in theory than in empirical results. Many existing empirical studies use an incidence function approach based on spatial patterns and key assumptions about extinction and colonization rates. Here we recast these assumptions as hypotheses to be tested using 18 years of historic detection survey data combined with four years of data from a new monitoring program for the Lower Keys marsh rabbit. We developed a new model to estimate probabilities of local extinction and colonization in the presence of nondetection, while accounting for estimated occupancy levels of neighboring patches. We used model …
Testing Metapopulation Concepts: Effects Of Patch Characteristics And Neighborhood Occupancy On The Dynamics Of An Endangered Lagomorph, Mitchell J. Eaton, Phillip T. Hughes, James E. Hines, James D. Nichols
Testing Metapopulation Concepts: Effects Of Patch Characteristics And Neighborhood Occupancy On The Dynamics Of An Endangered Lagomorph, Mitchell J. Eaton, Phillip T. Hughes, James E. Hines, James D. Nichols
United States Geological Survey: Staff Publications
Metapopulation ecology is a field that is richer in theory than in empirical results. Many existing empirical studies use an incidence function approach based on spatial patterns and key assumptions about extinction and colonization rates. Here we recast these assumptions as hypotheses to be tested using 18 years of historic detection survey data combined with four years of data from a new monitoring program for the Lower Keys marsh rabbit. We developed a new model to estimate probabilities of local extinction and colonization in the presence of nondetection, while accounting for estimated occupancy levels of neighboring patches. We used model …
Field-Scale Water And Solute Transport, Yang Yang
Field-Scale Water And Solute Transport, Yang Yang
Theses and Dissertations--Plant and Soil Sciences
Spatial variability of soil properties complicates the understanding of water and solute transport at the field scale. This study evaluated the impact of land use, soil surface roughness, and rainfall characteristics on water transport and Br- leaching under field conditions by means of a new experimental design employing scale-dependent treatment distribution. On a transect with two land use systems, i.e., cropland and grassland, rainfall intensity and the time delay between Br- application and subsequent rainfall were arranged in a periodically repetitive pattern at two different scales. Both scales were distinct from the scale of surface roughness as described …
Two-Source Energy Balance Model To Calculate E, T, And Et: Comparison Of Priestley-Taylor And Penman-Monteith Formulations And Two Time Scaling Methods, Paul D. Colaizzi, Nurit Agam, Judy A. Tolk, Steven R. Evett, Terry A. Howell, Prasanna H. Gowda, Susan A. O'Shaughnessy, William P. Kustas, Martha C. Anderson
Two-Source Energy Balance Model To Calculate E, T, And Et: Comparison Of Priestley-Taylor And Penman-Monteith Formulations And Two Time Scaling Methods, Paul D. Colaizzi, Nurit Agam, Judy A. Tolk, Steven R. Evett, Terry A. Howell, Prasanna H. Gowda, Susan A. O'Shaughnessy, William P. Kustas, Martha C. Anderson
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
The two-source energy balance (TSEB) model calculates the energy balance of the soil-canopy-atmosphere continuum, where transpiration is initially determined by the Priestley-Taylor equation. The TSEB was revised recently using the Penman-Monteith equation to replace the Priestley-Taylor formulation, thus better accounting for the impact of large and varying vapor pressure deficits (VPD) typical of advective, semiarid climates. This study is a comparison of the Priestley- Taylor and Penman-Monteith versions of the TSEB (termed TSEB-PT and TSEB-PM, respectively). Evaporation (E), transpiration (T), and evapotranspiration (ET) calculated by the TSEB-PT and TSEB-PM versions were compared to measurements obtained with microlysimeters, sap flow gauges, …
Ecotypes Of An Ecologically Dominant Prairie Grass (Andropogon Gerardii) Exhibit Genetic Divergence Across The U.S. Midwest Grasslands’ Environmental Gradient, Miranda M. Grey, Paul St. Amand, Nora M. Bello, Matthew B. Galliart, Mary Knapp, Karen A. Garrett, Theodore J. Morgan, Sarah G. Baer, Brian R. Maricle, Eduard D. Akhunov, Loretta C. Johnson
Ecotypes Of An Ecologically Dominant Prairie Grass (Andropogon Gerardii) Exhibit Genetic Divergence Across The U.S. Midwest Grasslands’ Environmental Gradient, Miranda M. Grey, Paul St. Amand, Nora M. Bello, Matthew B. Galliart, Mary Knapp, Karen A. Garrett, Theodore J. Morgan, Sarah G. Baer, Brian R. Maricle, Eduard D. Akhunov, Loretta C. Johnson
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Big bluestem (Andropogon gerardii) is an ecologically dominant grass with wide distribution across the environmental gradient of U.S. Midwest grasslands. This system offers an ideal natural laboratory to study population divergence and adaptation in spatially varying climates.
Objectives were to: (i) characterize neutral genetic diversity and structure within and among three regional ecotypes derived from 11 prairies across the U.S. Midwest environmental gradient, (ii) distinguish between the relative roles of isolation by distance (IBD) vs. isolation by environment (IBE) on ecotype divergence, (iii) identify outlier loci under selection and (iv) assess the association between outlier loci and climate.
Using two …
Simultaneous Adsorption Of 11 Volatile Organic Compounds By An Activated Carbon Made From Polystyrene Sulfonic Acid-Based Organic Salt, Alejandro Smith
Simultaneous Adsorption Of 11 Volatile Organic Compounds By An Activated Carbon Made From Polystyrene Sulfonic Acid-Based Organic Salt, Alejandro Smith
Dissertations and Theses
Activated carbon is used in water treatment worldwide due to its ability to adsorb many different contaminants from water. The high adsorption capacity of activated carbon is linked to its high internal surface area and micro/meso- porosity. In this work an activated carbon obtained from polystyrene sulfonic acid-based organic salt was examined to simultaneously adsorb eleven volatile organic compounds from aqueous solution. Adsorption data were modeled with different isotherms to determine the equilibrium adsorptive capacities for these compounds. The performance of the polymer-based activated carbon was then compared with that of a commercial wood-based activated carbon. The results indicate that …
Comparative Phylogeography Of Glassfrogs (Vitreorama) Endemic To The Brazilian Altantic Rainforest, Zoe Spanos
Comparative Phylogeography Of Glassfrogs (Vitreorama) Endemic To The Brazilian Altantic Rainforest, Zoe Spanos
Dissertations and Theses
The Brazilian Atlantic Forest harbors one of the most diverse faunas of the world, including 2-3% of all known vertebrate species. Understanding the role of both climate and landscape in shaping current biodiversity patterns has been the focus of many recent phylogeographic studies. Here I explore multiple factors thought to have impacted the generation of local diversity in the Brazilian Atlantic Forest (AF) using two montane, stream-associated species of glassfrogs – V. eurygnatha and V. uranoscopa. I integrate species distribution modeling, path analysis, and molecular data to test the role of climatic stability, rivers, mountain chains, and geographic distance in …
In Situ Measurement Of Mercury Ecotoxicological Effects On Stream Periphyton In Southwest Ohio, Jaclyn Elizabeth Klaus
In Situ Measurement Of Mercury Ecotoxicological Effects On Stream Periphyton In Southwest Ohio, Jaclyn Elizabeth Klaus
Browse all Theses and Dissertations
Periphyton are of ecological importance because of their critical role at the base of aquatic food webs as primary producers and as a significant source of energy to higher trophic levels in many stream ecosystems. This study examined the toxicity of mercury (Hg) to fluvial periphyton with in situ chemical exposure substrates. Two endpoints were used to measure toxicity of either total Hg or monomethylmercury (MMHg) to periphyton: periphyton biomass and metabolic activity, as a function of Hg concentrations in either periphyton or their exposure to the contaminants from two contrasting sediment types, a low-organic, sandy sediment type (SC) and …
Low Resolution Examination Of Cool-Water Carbonate Foraminifera Around Tasmania During The Pleistocene, Sara Jane Hughes
Low Resolution Examination Of Cool-Water Carbonate Foraminifera Around Tasmania During The Pleistocene, Sara Jane Hughes
Masters Theses
Benthic foraminifera from nine sediment samples recovered during Ocean Drilling Program (ODP) Leg 189: The Tasman Gateway were examined to determine how changing Southern Ocean conditions affect benthic foraminiferal populations. All samples come from Site 1168 situated 70km from the coast of Tasmania on the western continental slope (2463 m below the surface) and are spaced at roughly 150,000 years apart. Identifications of benthic foraminifera were done with a dissecting microscope and several reference books. Foraminifera were correlated with environmental proxy data obtained from Brughmans (2003) (total organic carbon, carbonate, siliciclastics, coarse fractions, chlorin, barium, aluminum, iron, and titanium) and …
Investigation Of Strategies To Promote Effective Teacher Professional Development Experiences In Earth Science, Carol A. Engelmann
Investigation Of Strategies To Promote Effective Teacher Professional Development Experiences In Earth Science, Carol A. Engelmann
Dissertations, Master's Theses and Master's Reports - Open
This dissertation serves as a call to geoscientists to share responsibility with K-12 educators for increasing Earth science literacy. When partnerships are created among K-12 educators and geoscientists, the synergy created can promote Earth science literacy in students, teachers, and the broader community. The research described here resulted in development of tools that can support effective professional development for teachers. One tool is used during the planning stages to structure a professional development program, another set of tools supports measurement of the effectiveness of a development program, and the third tool supports sustainability of professional development programs. The Michigan Teacher …
Ionic Liquid Extraction Unveils Previously Occluded Humicbound Iron In Peat Porewater, Timothy J. Veverica
Ionic Liquid Extraction Unveils Previously Occluded Humicbound Iron In Peat Porewater, Timothy J. Veverica
Dissertations, Master's Theses and Master's Reports - Open
Extracellular iron reduction has been suggested as a candidate metabolic pathway that may explain a large proportion of carbon respiration in temperate peatlands. However, the o-phenanthroline colorimetric method commonly employed to quantitate iron and partition between redox species is known to be unreliable in the presence of humic and fulvic acids, both of which represent a considerable proportion of peatland dissolved organic matter. We propose ionic liquid extraction as a more accurate iron quantitation and redox speciation method in humic-rich peat porewater. We evaluated both o-phenanthroline and ionic liquid extraction in four distinct peatland systems spanning a gradient of physico-chemical …
Denitrification In Soils: From Genes To Environmental Outcomes, Jianqiu Zheng
Denitrification In Soils: From Genes To Environmental Outcomes, Jianqiu Zheng
Dissertations, Master's Theses and Master's Reports - Open
Denitrification is an important process of global nitrogen cycle as it removes reactive nitrogen from the biosphere, and acts as the primary source of nitrous oxide (N2O). This thesis seeks to gain better understanding of the biogeochemistry of denitrification by investigating the process from four different aspects: genetic basis, enzymatic kinetics, environmental interactions, and environmental consequences. Laboratory and field experiments were combined with modeling efforts to unravel the complexity of denitrification process under microbiological and environmental controls.
Dynamics of denitrification products observed in laboratory experiments revealed an important role of constitutive denitrification enzymes, whose presence were further confirmed …