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Articles 13831 - 13860 of 17797
Full-Text Articles in Entire DC Network
Organic Geochemical Investigations Of Urban Sediments By Pyrolysis-Gas Chromatography / Mass Spectroscopy, Kevin Olsen
Organic Geochemical Investigations Of Urban Sediments By Pyrolysis-Gas Chromatography / Mass Spectroscopy, Kevin Olsen
Theses, Dissertations and Culminating Projects
Pyrolysis-Gas Chromatography / Mass Spectrometry (Py-GC/MS) can be used to study the organic matter in sedimentary environments.
An urban sediment is not simply defined by proximity to a city. Because cities have anthropogenic contamination, one important urban sediment characteristic is ongoing recontamination. Another is legacy contamination from industrial activity and a third is the alteration of natural bio-geochemical systems.
Two case studies are presented. The surface sediments of the Gateway National Recreation Area were sampled during the summer of 2007. The ratio of two pyrolysis products, Vinylguiacol, from terrestrial plant lignins, and Indole, from proteins, (VGI Index) is moderately well …
Porosity Development Within Lobes To Downslope Ramp Deposits On A Prograding Carbonate Shelf Of The Kinderhookian To Osagean Series In Northwest Arkansas, Elizabeth Marchese
Porosity Development Within Lobes To Downslope Ramp Deposits On A Prograding Carbonate Shelf Of The Kinderhookian To Osagean Series In Northwest Arkansas, Elizabeth Marchese
Graduate Theses and Dissertations
Carbonate bodies with lobate geometries form a substantial part of the Osagean (early Mississippian) section in northwest Arkansas. The purpose of this study is to isolate and describe a single lobe from three-dimensional exposures in quarry walls to provide criteria by which lobe and lobe porosity can be recognized in the subsurface. Carbonate sediment generated on the Mississippian Burlington shelf moved southward by gravity flows from the shelf margin to positions on a prograding ramp in Arkansas where overlapping deposits with lobate geometries accumulated. These deposits are recognized in outcrops of the Boone Formation. Stratigraphic units within the Boone are …
Plant-Microbial Interactions Change Along A Prairie Restoration Chronosequence, Anna Herzberger
Plant-Microbial Interactions Change Along A Prairie Restoration Chronosequence, Anna Herzberger
Undergraduate Honors Theses
Soil microbial communities are critical in determining the performance and density of species in plant communities. However, their role in regulating the success of restorations is much less clear. This study assessed the ability of soil microbial communities to regulate the growth and performance of two potentially dominant grasses and two common forbs in prairie restorations. Specifically, I examined the effects of soil microbial communities along a restoration chronosequence from agricultural fields to remnant prairies using experimentally inoculated soils. The two grass species, Andropogon gerardii and Sorghastrum nutans, produced larger biomass with the agricultural inoculates and experienced a decline …
Linking Mineral Deposits To Speleogenetic Processes In Cova Des Pas De Vallgornera (Mallorca, Spain), Bogdan P. Onac, Joan J. Fornós, Antoni Merino, Joaquín Ginés, Jacqueline Diehl
Linking Mineral Deposits To Speleogenetic Processes In Cova Des Pas De Vallgornera (Mallorca, Spain), Bogdan P. Onac, Joan J. Fornós, Antoni Merino, Joaquín Ginés, Jacqueline Diehl
International Journal of Speleology
Cova des Pas de Vallgornera (CPV) is the premier cave of the Balearic Archipelago. Over 74 km of passages develop within two carbonate lithofacies (reef front and back reef), which ultimately control the patterns of the cave and to some degree its mineral infilling. The diversity of speleothem-forming minerals is four times greater around or within hypogene-related features (vents, rims, cupolas), compared to any other vadose passages in the cave. The mineralogy of speleothems (crusts, nodules, crystals, earthy masses) associated with hypogene features in the seaward upper maze of Sector F is characterized by the presence of aragonite, ankerite, huntite, …
A Petrographic Analysis Of The Relationship Between Porosity And Organic Matter In The Permian Phosphoria Formation Of Northeastern Utah, Larry Tackett
All Graduate Plan B and other Reports, Spring 1920 to Spring 2023
The Permian Phosphoria Formation is a reservoir for oil and gas in the western United States, as well as a major source of phosphate. This study examined the relationship between phosphate richness and porosity exhibited in the formation. Petrographic analysis was carried out on rock samples collected from the Phosphoria (Park City) Formation located north of Vernal, Utah, on the southern flank of the Uinta Mountains.
The analysis demonstrated an inverse relationship between organic richness and porosity in the Phosphoria Formation. Porosity is controlled by lithology, amount of cementation, weathering, and amount of fecal pellets, which are the source of …
Estimating Nitrogen Fixation Rates, Importance, And Short-Term Efficiency In Small, Temperate Reservoirs Using Delta15n Techniques, Bryant Christopher Baker
Estimating Nitrogen Fixation Rates, Importance, And Short-Term Efficiency In Small, Temperate Reservoirs Using Delta15n Techniques, Bryant Christopher Baker
Graduate Theses and Dissertations
Nitrogen (N2) fixation can give certain species of cyanobacteria a competitive advantage in lake and reservoir phytoplankton. These species of cyanobacteria, along with others that cannot fix N2, can form toxic compounds that impair water quality when present in high concentrations. N2 fixation rates may be substantial in small (< 1.0 km2), temperate reservoirs since these systems experience thermal stratification and often nitrogen (N) limitation throughout a substantial proportion of the year. However, the effects of N2 fixation on N cycling, alleviation of short-term N limitation, and water quality are not well-understood. A mesocosm experiment and ecosystem-scale observational study were conducted to 1) determine the efficiency of N2 fixation under varying N relative to phosphorus (P) supply, 2) examine the effects of N2 fixation on autotrophic biomass accumulation and microcystin production, and 3) measure N2 fixation rates and importance to autotrophic N demand and zooplankton N assimilation. Results of the mesocosm experiment indicated that N2 fixation was increased at low N:P supply under high P. However, N2 fixation was inefficient at alleviating N limitation when fixed N was the primary source of N. Additionally, microcystin production occurred only at high N:P supply when N2 fixation was low, indicating that reducing external N inputs may have a positive effect on water quality. Results of whole-reservoir determination of N2 fixation using seston δ15N natural abundances indicated that N2 fixation rates throughout the warm season were substantial and influenced by water temperature. Annual N2 fixation rates ranged from 2.2 - 6.6 g N m-2 yr-1, and contributed up to 19% of the annual autotrophic N demand. Zooplankton were assimilating fixed N in most of the study reservoirs, representing a possible mechanism of ecosystem fixed N retention. Collectively, these results suggest that N2 fixation plays a substantial role in N cycling in small, temperate reservoirs, but likely cannot alleviate short-term N limitation.
Analysis Of Environmental Influences On Dressed Stone Decay: A Case Study Of Tafoni Development On A Hewn Djinn Block In Petra, Jordan, Kaelin M. Groom
Analysis Of Environmental Influences On Dressed Stone Decay: A Case Study Of Tafoni Development On A Hewn Djinn Block In Petra, Jordan, Kaelin M. Groom
Graduate Theses and Dissertations
Petra, Jordan captivates tourists and researchers with its dramatic sandstone cliffs, Nabatean, Roman, Byzantine and Roman architecture, and rich cultural heritage. However, increasing tourism in the valley is exacerbating stone degradation and complicating heritage management. This research analyzed environmental influences on dressed stone decay via tafoni development and evaluating cell evolution on an isolated hewn feature, known as Djinn Block X. Resembling other sandstone blocks found in the area, this irregular sandstone monument exhibits faces ranging in size from 2.5m by 3.5m to 3.9m to 4.2m (29m perimeter). Protruding features, incisions along the top, and a large platform attached to …
Fertilizer Nitrogen Uptake Efficiency In Soft Red Winter Wheat And The Ability Of N-Star To Detect Alkaline Hydrolyzable Nitrogen In Crop Residues, Lana Aubrey Clark
Fertilizer Nitrogen Uptake Efficiency In Soft Red Winter Wheat And The Ability Of N-Star To Detect Alkaline Hydrolyzable Nitrogen In Crop Residues, Lana Aubrey Clark
Graduate Theses and Dissertations
Soil testing methods such as the Illinois Soil Nitrogen Test (ISNT) and Direct Steam Distillation (DSD) have been developed which measure alkaline hydrolyzable-N (AH-N) as a means of estimating potentially mineralizable-N. Crop residues play an important role in N cycling. However, the ability of the ISNT and DSD methods to determine AH-N within crop residues is unknown. Therefore, the first objective of this study was to determine the ability of the ISNT and DSD to quantify potentially mineralizable-N within five different crop residues common to Arkansas. Corn (Zea mays L.), soybean (Glycine max, L.), wheat, rice (Oryza sativa, L.), and …
Methane Emissions And Ammonia Volatilization From Drill-Seeded, Delayed-Flood Rice On A Silt-Loam Soil In Arkansas, Christopher Wade Rogers
Methane Emissions And Ammonia Volatilization From Drill-Seeded, Delayed-Flood Rice On A Silt-Loam Soil In Arkansas, Christopher Wade Rogers
Graduate Theses and Dissertations
The Environmental Protection Agency (EPA) currently uses a single methane (CH4) emissions factor of 160 kg CH4-C ha-1 for a primary rice (Oryza sativa L.) crop. The emissions factor is based on studies that do not adequately represent current management practices in Arkansas. Another concern is pre-flood fertilizer nitrogen (N) management, as the common N source, urea, is prone to loss via ammonia (NH3) volatilization. Thus, the objective of this research was to investigate trace gas emissions from rice on a silt-loam soil, including CH4 emissions as influenced by nitrogen (N) fertilization (i.e., optimal N and no N) in 2011, …
Three-Dimensional Reconstruction Of Marine Clay Nano- And Microstructure By Transmission Electron Microscopy: Analysis Of Fabric And Pore Network, Jessica Rae Gardner Douglas
Three-Dimensional Reconstruction Of Marine Clay Nano- And Microstructure By Transmission Electron Microscopy: Analysis Of Fabric And Pore Network, Jessica Rae Gardner Douglas
Master's Theses
Three-dimensional reconstructions of marine fine-grained sediment open a new dimension for studying nano- and microscale organo-clay fabric important to improving and advancing organic matter (OM) sequestration and fluid flow dynamics modeling. I created 3-D reconstructions of clay fabric and pore pathways from serial sections and photographic mosaics obtained using transmission electron microscopy. These reconstructions show aggregations of clay domains, surrounding OM, and pore networks. I examined a Model sample (laboratory consolidated) with 1% OM and a Natural sample (polychaete fecal pellet) with high levels of OM. Three-dimensional reconstructions were segmented into 300 nm cube subsamples to make highly localized qualitative …
Pore Water Extraction For Unsaturated Zone Isotope Research: An Investigation Using An Immiscible Displacement Fluid And A Centrifuge, Caitlin Burnett Weaver
Pore Water Extraction For Unsaturated Zone Isotope Research: An Investigation Using An Immiscible Displacement Fluid And A Centrifuge, Caitlin Burnett Weaver
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Accurate and reliable pore water extraction techniques are important to an array of scientific fields including, but not limited to, hydrogeology, soil science, and paleoenvironmental research. The aim of the current project is to test the applicability of an immiscible displacement extraction technique for stable isotopes of water under a range of textural, hydrologic, and chemical conditions. In this study, laboratory experiments were conducted to establish the extent to which the proposed method 1) achieves sufficient yield for laboratory isotopic analyses, 2) results in isotopic exchange between water and the displacement fluid, 3) conserves initial isotopic compositions of spike test …
Developing Scientific Literacy In Introductory Laboratory Courses: A Model For Course Design And Assessment, Benjamin E. Surpless, Michelle M. Bushey, M. Halx
Developing Scientific Literacy In Introductory Laboratory Courses: A Model For Course Design And Assessment, Benjamin E. Surpless, Michelle M. Bushey, M. Halx
Earth and Environmental Geosciences Faculty Research
Although science educators at all levels have focused on teaching students scientific literacy for nearly five decades, studies indicate that the average student remains far from scientifically literate. To address this issue at the local level, faculty at Trinity University, in San Antonio, Texas, significantly revised the curriculum of an existing introductory physical geology laboratory course. The course, which satisfies general education requirements at Trinity, was revised to provide students learning opportunities in a scientific process context as part of a new science literacy initiative. This effort was spurred by general dissatisfaction with the existing curricular structure of the course …
Speleothems In Cova Des Pas De Vallgornera: Their Distribution And Characteristics Within An Extensive Coastal Cave From The Eogenetic Karst Of Southern Mallorca (Western Mediterranean), Antoni Merino, Joaquín Ginés, Paola Tuccimei, Michele Soligo, Joan J. Fornós
Speleothems In Cova Des Pas De Vallgornera: Their Distribution And Characteristics Within An Extensive Coastal Cave From The Eogenetic Karst Of Southern Mallorca (Western Mediterranean), Antoni Merino, Joaquín Ginés, Paola Tuccimei, Michele Soligo, Joan J. Fornós
International Journal of Speleology
The abundance and variety of speleothems are undoubtedly among the remarkable features of Cova des Pas de Vallgornera, the longest cave system in Mallorca Island developed in the eogenetic karst of its southern coast. Due to the monotonous carbonate lithology of the area, most of the speleothems are composed of calcite and in a few cases aragonite, although other minerals are also represented (e.g., gypsum, celestine, barite.). However, in spite of the rather common mineralogy of the speleothems, its distribution results strongly mediated by the lithologic and textural variability linked to the architecture of the Upper Miocene reefal rocks. Apart …
Molecular Analyses Of Microbial Abundance And Diversity In The Water Column Of Anchialine Caves In Mallorca, Spain, Damian Menning, Liana M. Boop, Elaina D. Graham, James R. Garey
Molecular Analyses Of Microbial Abundance And Diversity In The Water Column Of Anchialine Caves In Mallorca, Spain, Damian Menning, Liana M. Boop, Elaina D. Graham, James R. Garey
International Journal of Speleology
Water column samples from the island of Mallorca, Spain were collected from one site in Cova des Pas de Vallgornera (Vallgornera) and three sites (Llac Martel, Llac Negre, and Llac de les Delícies) in Coves del Drac (Drac). Vallgornera is located on the southern coast of Mallorca approximately 57 km southwest of Coves del Drac. Drac is Europe's most visited tourist cave, whereas Vallgornera is closed to the public. Water samples were analyzed for water chemistry using spectrophotometric methods, by quantitative PCR for estimated total abundance of microbial communities, and by length heterogeneity PCR for species richness and relative species …
Understanding Selenium Distribution In Lake Mead Using A Three-Dimensional Hydrodynamic Based Water Quality Model, Xiaolu Wei
UNLV Theses, Dissertations, Professional Papers, and Capstones
Shallow groundwater and surface drainages in Las Vegas Wash are known to have elevated level of selenium which mainly comes from the naturally occurring geological hotspots on the southeast side of the Las Vegas Valley. Selenium fate and transport after it enters into Lake Mead from the Las Vegas Wash are not clearly understood. An open sourced three-dimensional Environmental Fluid Dynamic Code model (EFDC), developed by the United States Environmental Protection Agency, was used to model movement of selenium in the Boulder Basin, Lake Mead. The model was calibrated by observed data from 2006 to 2007. The concept of Lagrangian …
Restoration Of Tryptophan Hydroxylase Functions And Serotonin Content In The Atlantic Croaker Hypothalamus By Antioxidant Treatment During Hypoxic Stress, Md. Saydur Rahman, Peter Thomas
Restoration Of Tryptophan Hydroxylase Functions And Serotonin Content In The Atlantic Croaker Hypothalamus By Antioxidant Treatment During Hypoxic Stress, Md. Saydur Rahman, Peter Thomas
School of Earth, Environmental, & Marine Sciences Faculty Publications
Antioxidants are prototypical scavengers of oxygen-free radicals and have been shown to prevent neuroendocrine dysfunction in vertebrates during oxidative stress. In the present study, we investigated whether antioxidant treatment can reverse hypoxia-induced down-regulation of hypothalamic tryptophan hydroxylase (TPH) and serotonergic functions in Atlantic croaker. Hypothalamic neuronal contents of TPH-1 and TPH-2 proteins, serotonin (5-hydroxytryptamine, 5-HT) and its precursor, 5-hydroxytryptophan (5-HTP) as well as hypothalamic TPH-1 and TPH-2 mRNA expression and TPH activity were measured in croaker after exposure to hypoxia and treatment with pharmacological agents. Multiple injections of N-ethylmaleimide, a sulfhydryl alkylating agent, caused comparable decreases in hypothalamic TPHs functions …
Landscape Evolution Of The Needles Fault Zone, Utah, Investigated Through Chronostratigraphic And Terrain Analyses, Faye L. Geiger
Landscape Evolution Of The Needles Fault Zone, Utah, Investigated Through Chronostratigraphic And Terrain Analyses, Faye L. Geiger
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Arcing eastward from the deep gorge of Cataract Canyon on the Colorado River is a series of aligned valleys (graben) and ridges (horst). This unusual landscape has formed as subsurface salt deforms toward the river and dissolves away, causing the overlying rocks to fault, slide, and subside. Geologists have long been interested in this actively evolving area they call the Needles fault zone, because understanding its mechanics and origin may shed light on how faults work in general and similar, yet inaccessible places like offshore rift zones or even the surface of the Moon. Despite this interest, the timing and …
Estimating Unsaturated Flow Properties In Coarse Conglomeratic Sediment, Michael James Thoma Jr.
Estimating Unsaturated Flow Properties In Coarse Conglomeratic Sediment, Michael James Thoma Jr.
Boise State University Theses and Dissertations
In this dissertation, I address the lack of knowledge of unsaturated flow in coarse, conglomeratic sediment by determining if functional θ-ψ-K relationships, specifically van Genuchten-Mualem (VGM) relationships, developed to predict unsaturated flow in relatively fine-grained sediment can be directly applied to coarse, conglomeratic sediment. In the summer of 2011, a field-scale infiltration test was conducted at the Boise Hydrogeophysical Research Site to determine if functional ψ-θ-K relationships could be applied to infiltration in coarse, conglomeratic sediment, and to estimate parameter values for the VGM relationships. Vertically and laterally distributed ψ(t) and θ( …
Spreading The Char: The Importance Of Local Compatibility In The Diffusion Of Biochar Systems To The Smallholder Agriculture Community Context, Laura C. V. Munoz
Spreading The Char: The Importance Of Local Compatibility In The Diffusion Of Biochar Systems To The Smallholder Agriculture Community Context, Laura C. V. Munoz
Pomona Senior Theses
This thesis enters the context of smallholder agriculture communities in the developing world. It explores the potentials of biochar and what biochar systems could bring to the smallholder communities while simultaneously bringing environmental benefits. It then acknowledges the challenges of diffusion –the spreading of an unfamiliar innovation. It seeks to answer the question of what will make diffusion of biochar systems more successful in the smallholder context, fixating on the characteristic of compatibility as well as the role local community members can play in making a new biochar system more visible to the rest of the communities.
Molecular Systematics, Historical Biogeography, And Evolution Of Spider Wasps (Hymenoptera: Pompilidae), Juanita Rodriguez
Molecular Systematics, Historical Biogeography, And Evolution Of Spider Wasps (Hymenoptera: Pompilidae), Juanita Rodriguez
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The study of the diversity and classification of any group of organisms provides a foundation for further scientific studies in ecology, evolution, and conservation. Insects are among the most diverse organisms that inhabit the planet, but knowledge of their diversity and classification is still limited. One understudied group of insects is spider wasps. These are solitary parasitoids that use one spider to lay a single egg. There are approximately 5,000 described species, and many more to be described. Unfortunately, fewer than 10 scientists worldwide study these insects. One reason the group has not been very well studied is the difficulty …
Natural Radioactivity In Groundwater, Rocks And Sediments From Some Areas In The Uae: Distribution, Sources And Environmental Impact, Dalal Matar Al Shamsi
Natural Radioactivity In Groundwater, Rocks And Sediments From Some Areas In The Uae: Distribution, Sources And Environmental Impact, Dalal Matar Al Shamsi
Dissertations
Groundwater contains a certain amount of natural radioactivity that generally results from the decay of uranium, thorium and 40K isotopes. Knowledge of concentration levels, spatial distribution and sources of these isotopes in groundwater is crucial for environmentally safe and sustainable groundwater resources in the United Arab Emirates (UAE). This dissertation focuses on investigating the distribution, environmental impact and sources of 235U, 238U, 232Th, as well as the activity of gross β and α in groundwater in some locations in the UAE. Additionally, groundwater samples from Oman and selected aquifer rocks and sediments from the UAE were …
Characterization Of Cretaceous Chalk Microporosity Related To Depositional Texture: Based Upon Study Of The Upper Cretaceous Niobrara Formation, Denver-Julesburg Basin, Colorado And Wyoming, P D. Pahnke
Theses and Dissertations
Prompted by increased interest in understanding microporosity, recent efforts at describing and classifying pore types in mudstones have focused primarily on siliceous, gas producing unconventional reservoirs with little attention being paid to carbonate, mixed oil-and-gas producers. The Niobrara Formation in the Denver-Julesburg Basin is a self-sourced resource play producing oil and natural gas from low permeability chalks. Key reservoir lithologies consist of chalk, chalky marl and marl. These lithologies contain flattened chalk fecal pellets which play a significant role in providing porosity. Integration of depositional fabric with pore-type distribution emphasizes the unique textural and depositional nature of chalk and provides …
Effects Of Instrumentation On Dental Microwear Textures: Reanalysis And Augmentation Of An Early Hominin Sample, Anna Jacquelyn Ragni
Effects Of Instrumentation On Dental Microwear Textures: Reanalysis And Augmentation Of An Early Hominin Sample, Anna Jacquelyn Ragni
Graduate Theses and Dissertations
Dental microwear texture analysis has been refined to a methodology relying upon scanning confocal microscopy for its advantages of repeatability and standardized quantification. A new instrument, the Plu Neox (Sensofar Corp.) confocal profiler recently entered the market, sparking questions among dental anthropologists related to the advantages and efficacy of this new technology, which has better resolution and lighting properties than previously available white-lighted based confocal profilers. This thesis reports on three complementary studies that set out to evaluate the comparability of the Plu Neox to the Plu Standard system and assess its ability to distinguish primates on the basis of …
Late Pleistocene And Holocene Bison Of Grand Canyon And Colorado Plateau: Implications From The Use Of Paleobiology For Natural Resource Management Policy, Jeffrey M. Martin
Late Pleistocene And Holocene Bison Of Grand Canyon And Colorado Plateau: Implications From The Use Of Paleobiology For Natural Resource Management Policy, Jeffrey M. Martin
Electronic Theses and Dissertations
Bison spp. (bison) fossils are scarce on the Colorado Plateau, especially within the greater Grand Canyon region. Because of the poor fossil record for bison on the plateau and in Grand Canyon National Park, various resource managers have surreptitiously designated bison a nonnative and human-introduced species. The lack of evidence for bison seems to be the result of collection bias rather than a true lack of bison remains. Today, Grand Canyon National Park has a neighboring herd of 350 bison that have meandered unwantedly onto National Park lands from neighboring Forest Service and State of Arizona lands. This study spatiotemporally …
Non-Anguimorph Lizards Of The Late Oligocene And Early Miocene Of Florida And Implications For The Reorganization Of The North American Herpetofauna, Kevin Chovanec
Electronic Theses and Dissertations
Paleokarst deposits from the Oligo-Miocene of northern Florida preserve undescribed herpetofaunal remains that fill important temporal and geographic gaps in our understanding of Cenozoic lizard evolution. Here I describe and discuss the non-anguimorph lizard diversity of the Brooksville 2 (Ar2) and Miller (He1) local faunas to test for patterns of regional and latitudinal provincialism in the contemporary North American record. Collectively, the sites are significant for documenting 1) extralimital occurrences of the tropical clades Anolis and Corytophaninae, 2) a substantial temporal range extension of the modern southeastern endemic Rhineuridae, 3) the earliest record of eublepharid gekkotans from North America, and …
Effect Of Australian Pine (Casuarina Equisetifolia) Canopy Density On The Understory Plant Community On San Salvador, Bahamas, Jeffry Anderson, Anna Baumgartner
Effect Of Australian Pine (Casuarina Equisetifolia) Canopy Density On The Understory Plant Community On San Salvador, Bahamas, Jeffry Anderson, Anna Baumgartner
Celebrating Scholarship & Creativity Day (2011-2017)
Casuarina equisetifolia, or Australian pine, is an invasive angiosperm species on the island of San Salvador, The Bahamas. It was originally found only in Southeast Asia and Australia. This tree is unique in that its leaves are much reduced and occur in whorls around the photosynthetic branchlets. It has been established that this tree contributes to the increased erosion of sediment on the dunes of San Salvador (Sealey 1998). This study investigated several possible factors contributing to differences in the understory plant community which may contribute to this erosion including leaf litter density, shading, and soil pH. It is …
Body Size And Species Richness Changes In Glyptosaurinae (Squamata: Anguidae) Through Climatic Transitions Of The North American Cenozoic, Sara Elshafie
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Poikilothermic vertebrates offer excellent climate proxies based on relationships between environment and measurable variables such as body size and species richness. Relationships of these variables in lizards to environmental transitions over long time scales are poorly understood. Here I show that patterns of body size and species richness in a lizard clade, Glyptosaurinae (Squamata: Anguidae), correspond to known histories of paleotemperatures through the Cenozoic of North America. Glyptosaurines have the richest fossil record among North American Cenozoic lizards and exhibit a wide range of skull sizes. In order to estimate body size for glyptosaurines and other fossil anguids, I collected …
Fossil Crocodilians From The High Guajira Peninsula Of Colombia, And The History Of Neogene Crocodilian Diversity In Tropical South America, Jorge W. Moreno-Bernal
Fossil Crocodilians From The High Guajira Peninsula Of Colombia, And The History Of Neogene Crocodilian Diversity In Tropical South America, Jorge W. Moreno-Bernal
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The greatest diversity of Cenozoic crocodilians occurred during the Miocene in equatorial South America. However, the origin of this high diversity and its relationship to environmental factors are poorly understood. Most described species come from localities assigned to Laventan (13.8-11.8 Ma) and Huayquerian (9.0-6.8 Ma) South American land mammal ages (SALMAS), whereas the record is sparse in the early to middle Miocene and after the latest Miocene and Pliocene. Field research in the Castilletes (early Miocene-Pliocene) Formation in the High Guajira Peninsula of Colombia provides new fossil data on the origin of Neotropical crocodylian diversity. The Castilletes Formation crops out …
The Surface Energy Balance And Its Drivers In A Boreal Peatland Fen Of Northwestern Russia, Benjamin R. K. Runkle, Christian Wille, Michal Gazovic, M. Wilmking, L. Kutzbach
The Surface Energy Balance And Its Drivers In A Boreal Peatland Fen Of Northwestern Russia, Benjamin R. K. Runkle, Christian Wille, Michal Gazovic, M. Wilmking, L. Kutzbach
Biological and Agricultural Engineering Faculty Publications and Presentations
Boreal peatland energy balances using the eddy covariance technique have previously been made in Alaska, Canada, Scandinavia, and Western Siberia, but not in the European portion of the Russian Federation. European Russia contains approximately 200,000 km2 of peatlands and has a boreal (subarctic), continental climate influencing the region’s energy balance. To help fill this research gap, the surface energy balance was determined for a boreal peatland fen in the Komi Republic of Russia for an 11-month period in 2008–2009 using the eddy covariance method. The total measurement period’s cumulative energy balance closure rate was 86%, with higher closure during the …
Rates Of Sustainable Forest Harvest Depend On Rotation Length And Weathering Of Soil Minerals, Matthew A. Vadeboncoeur, Steven P. Hamburg, Ruth D. Yanai, Joel D. Blum
Rates Of Sustainable Forest Harvest Depend On Rotation Length And Weathering Of Soil Minerals, Matthew A. Vadeboncoeur, Steven P. Hamburg, Ruth D. Yanai, Joel D. Blum
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Abstract
Removals of forest biomass in the northeastern US may intensify over the coming decades due to increased demand for renewable energy. For forests to regenerate successfully following intensified harvests, the nutrients removed from the ecosystem in the harvested biomass (including N, P, Ca, Mg, and K) must be replenished through a combination of plant-available nutrients in the soil rooting zone, atmospheric inputs, weathering of primary minerals, biological N fixation, and fertilizer additions. Few previous studies (especially in North America) have measured soil nutrient pools beyond exchangeable cations, but over the long rotations common in this region, other pools which …