Open Access. Powered by Scholars. Published by Universities.®
- Institution
-
- University of Kentucky (9522)
- University of Nebraska - Lincoln (1408)
- University of South Florida (620)
- Utah State University (606)
- University of Texas Rio Grande Valley (435)
-
- Old Dominion University (337)
- University of Arkansas, Fayetteville (292)
- Department of Primary Industries and Regional Development, Western Australia (266)
- Western Kentucky University (174)
- University of Nevada, Las Vegas (142)
- Portland State University (140)
- Boise State University (129)
- University of New Hampshire (127)
- Montclair State University (125)
- University of South Carolina (110)
- City University of New York (CUNY) (107)
- TÜBİTAK (107)
- Louisiana State University (105)
- Western Michigan University (98)
- South Dakota State University (93)
- University of Dar es Salaam (86)
- Missouri University of Science and Technology (84)
- University of Colorado Law School (84)
- The University of Southern Mississippi (78)
- University of North Dakota (74)
- Wright State University (71)
- University of Texas at El Paso (66)
- Chapman University (62)
- China Coal Technology and Engineering Group (CCTEG) (60)
- Universitas Padjadjaran (60)
- Keyword
-
- Grazing (393)
- Nitrogen (272)
- Climate change (237)
- Alfalfa (203)
- Soil (187)
-
- Grassland (174)
- Biodiversity (167)
- Sheep (167)
- Forage (164)
- Phosphorus (164)
- Western Australia (164)
- Pasture (159)
- Cattle (156)
- Water quality (154)
- Digestibility (146)
- Yield (141)
- Forage quality (137)
- Silage (137)
- Sustainability (126)
- Remote sensing (122)
- Legumes (120)
- Nutritive value (120)
- Groundwater (119)
- Hydrology (118)
- Geology (115)
- Stocking rate (115)
- Trifolium repens (113)
- Intake (112)
- Management (112)
- Drought (109)
- Publication Year
- Publication
-
- IGC Proceedings (1977-2023) (9261)
- United States Geological Survey: Staff Publications (519)
- School of Earth, Environmental, & Marine Sciences Faculty Publications (370)
- International Journal of Speleology (339)
- Memorandum (315)
-
- Theses and Dissertations (247)
- Faculty Publications (214)
- Department of Earth and Atmospheric Sciences: Faculty Publications (184)
- OES Faculty Publications (157)
- Electronic Theses and Dissertations (147)
- Graduate Theses and Dissertations (145)
- All Graduate Theses and Dissertations, Spring 1920 to Summer 2023 (121)
- School of Natural Resources: Dissertations, Theses, and Student Research (118)
- Bulletin of the University of Nebraska State Museum (1924–2023) (112)
- USF Tampa Graduate Theses and Dissertations (110)
- Masters Theses (109)
- Turkish Journal of Earth Sciences (107)
- School of Geosciences Faculty and Staff Publications (98)
- Tanzania Journal of Science (86)
- Department of Earth and Environmental Studies Faculty Scholarship and Creative Works (83)
- Geosciences Faculty Publications and Presentations (79)
- OES Theses and Dissertations (77)
- United States Geological Survey: Publications (69)
- Master's Theses (64)
- Masters Theses & Specialist Projects (64)
- Journal of the Arkansas Academy of Science (63)
- Open Access Theses & Dissertations (63)
- United States Environmental Protection Agency: Publications (63)
- Coal Geology & Exploration (60)
- Jurnal Kultivasi (60)
- Publication Type
- File Type
Articles 15181 - 15210 of 17792
Full-Text Articles in Entire DC Network
Optlime, A Bioecenomic Model Of Soil Acidity Management In Agricultural Systems, Chris Gazey
Optlime, A Bioecenomic Model Of Soil Acidity Management In Agricultural Systems, Chris Gazey
All other publications
Optlime is a model that represents the essential biological, physical and economic factors related to soil acidity management in Western Australia. The model allows users to define site and soil characteristics for an acidic scenario and then simultaneously assess likely outcomes for 2 different lime sources and application strategies. With and without liming scenarios are examined over a 20 year simulation so as to capture the long-term impacts of soil acidity management. Output provided allows you to examine the likely effect of liming on pH, exchangeable aluminium, yields, and profits. An investment appraisal is provided to show you how liming …
Ground-Penetrating Radar And Thermal Modeling Of Active Layer Thaw Beneath Arctic Streams, Troy Richard Brosten
Ground-Penetrating Radar And Thermal Modeling Of Active Layer Thaw Beneath Arctic Streams, Troy Richard Brosten
Boise State University Theses and Dissertations
Seasonal thaw depth beneath arctic streams significantly impacts physical and biological processes within arctic stream environments. The impact of greater seasonal thaw for extended periods of time can alter ecosystems that have, in the past, resulted from more prevalent permafrost environments. Effects of climatic change on arctic stream environments necessitate the need for more information on characteristics of seasonal thaw and processes that occur within the thawed layer. Multiple ground-penetrating radar (GPR) methods and one-dimensional (1D) thermal modeling were used to investigate seasonal thaw beneath arctic streams and determine the dominant thermal process.
Study sites were selected to include stream …
Gsi: Geo Scene Investigation! On-Site Programming (Grade 7), Discover Mojave: Forever Earth
Gsi: Geo Scene Investigation! On-Site Programming (Grade 7), Discover Mojave: Forever Earth
Curriculum materials (FE)
GSI: Geo Scene Investigation! introduces students to the differences between observations and interpretations and to some of the fundamental principles of geology. Students identify specific geologic processes and landforms in the landscape surrounding them at Lake Mead National Recreation Area (NRA) by solving mysteries with a set of geology-related clues.
Gambel Oak Growth Forms: Management Opportunities For Increasing Ecosystem Diversity, Scott R. Abella
Gambel Oak Growth Forms: Management Opportunities For Increasing Ecosystem Diversity, Scott R. Abella
Public Policy and Leadership Faculty Research
Gambel oak (Quercus gambelii) clones have several different growth forms in southwestern ponderosa pine (Pinus ponderosa) forests, and these growth forms each provide unique wildlife habitat and resource values. The purposes of this note are to review published growth-form classifications for Gambel oak, provide examples of ecological effects of different growth forms, and summarize management strategies for promoting desired growth forms. Four different growth-form classifications have been published, which generally recognize variants of three basic forms: shrubby thickets of small-diameter stems, pole-sized clumps, and large trees. These growth forms exemplify ecological and management tradeoffs. For example, shrubby forms provide browse …
Estimating Soil Seed Bank Characteristics In Ponderosa Pine Forests Using Vegetation And Forest-Floor Data, Scott R. Abella, Judith D. Springer
Estimating Soil Seed Bank Characteristics In Ponderosa Pine Forests Using Vegetation And Forest-Floor Data, Scott R. Abella, Judith D. Springer
Public Policy and Leadership Faculty Research
Soil seed banks are important for vegetation management because they contain propagules of species that may be considered desirable or undesirable for site colonization after management and disturbance events. Knowledge of seed bank size and composition before planning management activities facilitates proactive management by providing early alerts of exotic species presence and of abilities of seed banks to promote colonization by desirable species. We developed models in ponderosa pine (Pinus ponderosa) forests in northern Arizona to estimate the size and richness of mineral soil seed banks using readily observable vegetation and forestfloor characteristics. Regression models using three or fewer predictors …
Relating Groundwater To Seasonal Wetlands In Southeastern Wisconsin, Usa, John D. Skalbeck, Donald M. Reed, Randall J. Hunt, Jamie D. Lambert
Relating Groundwater To Seasonal Wetlands In Southeastern Wisconsin, Usa, John D. Skalbeck, Donald M. Reed, Randall J. Hunt, Jamie D. Lambert
United States Geological Survey: Staff Publications
Historically, drier types of wetlands have been difficult to characterize and are not well researched. Nonetheless, they are considered to reflect the precipitation history with little, if any, regard for possible relation to groundwater. Two seasonal coastal wetland types (wet prairie, sedge meadow) were investigated during three growing seasons at three sites in the Lake Michigan Basin, Wisconsin, USA. The six seasonal wetlands were characterized using standard soil and vegetation techniques and groundwater measurements from the shallow and deep systems. They all met wetland hydrology criteria (e.g., water within 30 cm of land surface for 5% of the growing season) …
Stereospecificity In Glucose Consumption: A New Approach To Martian Life Detection, Vienna R. Saccomanno, Henry J. Sun
Stereospecificity In Glucose Consumption: A New Approach To Martian Life Detection, Vienna R. Saccomanno, Henry J. Sun
Undergraduate Research Opportunities Program (UROP)
In 1976, the Viking mission made a remarkable discovery: Martian soil was capable of decomposing an organic nutrient broth to carbon dioxide as if it contained live microorganisms. However, a biological interpretation of this finding is in apparent contradiction with the gas chromatograph-mass spectrometer aboard the Viking landers, which showed Martian soil to be devoid of indigenous organics. To reconcile these findings, it has been hypothesized that unknown abiotic oxidants, such as peroxide and superoxide, are present on Mars and that they were responsible for its soil reactivity. The objective of this research is to develop a life detection method …
Potential Antimicrobial Properties Of The Cyanobacterium Microcoleus Vaginatus In Relationship To The Moss Bryum Argenteum, Crystal Erickson, Lloyd Stark
Potential Antimicrobial Properties Of The Cyanobacterium Microcoleus Vaginatus In Relationship To The Moss Bryum Argenteum, Crystal Erickson, Lloyd Stark
Undergraduate Research Opportunities Program (UROP)
Biological soil crusts play important ecological roles in arid desert regions. These crusts cycle nutrients, prevent wind/water erosion, and form the basis of food chains and soil formation in desert communities. Primary components of these structures include two desert moss species Bryum argenteum and Syntrichia caninervis, and Microcoleus vaginatus, a cyanobacterium. Our Phase I experiment strongly suggests that in an environment of intense light, a condition of stress to Syntrichia caninervis, there is an increase in shoot regeneration when cyanobacteria are present compared to when they are absent. Microcoleus is a highly motile species and our lab observations of fewer …
Geology And Hydrology Of Karst In West-Central And North-Central Florida, Lee J. Florea
Geology And Hydrology Of Karst In West-Central And North-Central Florida, Lee J. Florea
Earth, Environmental, and Atmospheric Sciences Faculty Publications
The state of Florida is blessed with the highest density of large springs in North America and hundreds of smaller springs where the water from limestone aquifers returns to the surface (Scott et al., 2004). Spectacular underwater caves supply water to these springs. Lesser known are the equally fantastic air-filled caves of Florida and South Georgia (Florea, 2006; Lane, 1986). This paper features these underwater and airfilled caves, explores the impact of changes in sea level on karst in this near-coastal environment, and establishes several geologic and hydrologic characteristics that distinguish karst in the limestones of the southeast from karst …
Influence Of Bioirrigation On Metal Distribution Within Burrows, Terri Shattuck
Influence Of Bioirrigation On Metal Distribution Within Burrows, Terri Shattuck
Masters Theses
Bioirrigation is the increase of solute transport resulting from introduction of oxygenated water from the surface into the more reduced environment deep within the burrow. Fe and Mn hydr-(oxides) accumulate on burrow margins in response to the oxygen flux into suboxic porewaters. This has been shown to trap trace metals (Harding and Risk, 1986; Tessier and Campbell, 1988; Tessier et al., 1979, 1982). The diagenesis, mobility, and transport of metals contribute to the bioavailability of metals in the environment possibly to the extent of harming ecosystems; especially in coastal areas with buried waste. This study assesses Fe and trace metal …
Fish Distributions And Nutrient Cycling In Streams: Can Fish Create Biogeochemical Hotspots, Peter B. Mcintyre, Alexander S. Flecker, Michael J. Vanni, James M. Hood, Brad W. Taylor, Steven A. Thomas
Fish Distributions And Nutrient Cycling In Streams: Can Fish Create Biogeochemical Hotspots, Peter B. Mcintyre, Alexander S. Flecker, Michael J. Vanni, James M. Hood, Brad W. Taylor, Steven A. Thomas
Dartmouth Scholarship
Rates of biogeochemical processes often vary widely in space and time, and characterizing this variation is critical for understanding ecosystem functioning. In streams, spatial hotspots of nutrient transformations are generally attributed to physical and microbial processes. Here we examine the potential for heterogeneous distributions of fish to generate hotspots of nutrient recycling. We measured nitrogen (N) and phosphorus (P) excretion rates of 47 species of fish in an N-limited Neotropical stream, and we combined these data with population densities in each of 49 stream channel units to estimate unit- and reach-scale nutrient recycling. Species varied widely in rates of N …
Optimization And Validation Of An Enzymatic Method To Quantify Glucose In Potato Tubers, Engil Isadora Pujol Pereira, Tatiana Emanuelli, Dilson Antonio Bisognin, Sergio T. De Freitas
Optimization And Validation Of An Enzymatic Method To Quantify Glucose In Potato Tubers, Engil Isadora Pujol Pereira, Tatiana Emanuelli, Dilson Antonio Bisognin, Sergio T. De Freitas
School of Earth, Environmental, & Marine Sciences Faculty Publications
The processing industry requires potato tubers with low levels of reduced sugars, glucose and fructose, which is responsible for the whiteness of the chip color. The objective of this research was to optimize and validate a simple, inexpensive, and precise enzymatic method to quantify glucose in potato tubers. This method will be useful in breeding programs to select clones for processing purposes with low levels of glucose. The validation procedure followed the recommendations described in INMETRO document DOQ-CGCRE-008 in 2003. The method was linear between 1.25 to 40µg of glucose in the sample. The quantification limit was 0.319mg g-1 of …
Mechanical Properties Of Plant Underground Storage Organs And Implications For Dietary Models Of Early Hominins, Nathaniel J. Dominy, Erin R. Vogel, Justin D. Yeakel, Paul J. Constantino, Peter W. Lucas
Mechanical Properties Of Plant Underground Storage Organs And Implications For Dietary Models Of Early Hominins, Nathaniel J. Dominy, Erin R. Vogel, Justin D. Yeakel, Paul J. Constantino, Peter W. Lucas
Biological Sciences Faculty Research
The diet of early human ancestors has received renewed theoretical interest since the discovery of elevated d13C values in the enamel of Australopithecus africanus and Paranthropus robustus. As a result, the hominin diet is hypothesized to have included C4 grass or the tissues of animals which themselves consumed C4 grass. On mechanical grounds, such a diet is incompatible with the dental morphology and dental microwear of early hominins. Most inferences, particularly for Paranthropus, favor a diet of hard or mechanically resistant foods. This discrepancy has invigorated the longstanding hypothesis that hominins consumed plant underground storage organs (USOs). Plant USOs are …
Mitochondrial Dna Evolution In The Anaxyrus Boreas Species Group, Anna M. Goebel, Tom A. Ranker, Paul Stephen Corn, Richard G. Olmstead
Mitochondrial Dna Evolution In The Anaxyrus Boreas Species Group, Anna M. Goebel, Tom A. Ranker, Paul Stephen Corn, Richard G. Olmstead
United States Geological Survey: Staff Publications
The Anaxyrus boreas species group currently comprises four species in western North America including the broadly distributed A. boreas, and three localized species, Anaxyrus nelsoni, Anaxyrus exsul and Anaxyrus canorus. Phylogenetic analyses of the mtDNA 12S rDNA, cytochrome oxidase I, control region, and restriction sites data, identified three major haplotype clades. The Northwest clade (NW) includes both subspecies of A. boreas and divergent minor clades in the middle Rocky Mountains, coastal, and central regions of the west and Pacific Northwest. The Southwest (SW) clade includes A. exsul, A. nelsoni, and minor clades in southern California. …
Compost Production And Use In Horticulture, Bob Paulin, Peter O'Malley
Compost Production And Use In Horticulture, Bob Paulin, Peter O'Malley
Bulletins 4000 -
Maintaining and improving soil organic carbon levels is becoming an increasingly important aspect of modern farming. Compost provides potentially one of the most effective ways of applying organic matter to soils and improving organic carbon levels.
Improving soil organic carbon is directly related to soil quality and performance. Increased quality reflects improved biological function (soil health), fertility and physical attributes that include better drainage, reduced compaction and erosion, and improved moisture-holding capability, at least for lighter soils.
Compost is not the only option available. Others include the use of cover or break crops, reducing the use of cultivations, selecting safe …
Gsi: Geo Scene Investigation! On-Site Programming, Support Materials (Grade 7), Discover Mojave: Forever Earth
Gsi: Geo Scene Investigation! On-Site Programming, Support Materials (Grade 7), Discover Mojave: Forever Earth
Curriculum materials (FE)
What happened geologically to produce the landscape we see today? What was the stage like that ultimately produced the Colorado River? What are the processes that are still at work today?
To begin exploring and discovering the answers to these questions, we can look at what’s happened in the past and also examine the clues that are evident on today’s landscape. Lake Mead’s geologic past can be organized like acts in a play. These geologic “acts” represent the area’s significant geologic events. The acts are not equal in terms of time (millions of years), nor is all geologic time accounted …
Microtextures Of Cyanobacterial Mats In Siliciclastic Sedimentary Environments (Modern & Ancient): Applications To The Search For Life On Mars, Dina M. Bower
OES Theses and Dissertations
The current Mars Exploration Rover Program (MER) is one of NASA's most successful missions. The aim of the MER is to explore for possible life on the surface of Mars. My thesis developed new methods of how to detect and to identify microbial mats in siliciclastic sediments (modern and ancient), and to make recommendations on the applicability of MISS as biosignatures. Predominantly, I employed instrumentation portable by future rovers. To search for life on other planets, we need to have information on how this life might look. Most astrobiological studies therefore focus on Earthly analogues of life and its habitats. …
Hyporheic Exchange And Water Chemistry Of Two Arctic Tundra Streams Of Contrasting Geomorphology, Morgan J. Greenwald, William B. Bowden, Michael N. Gooseff, Jay P. Zarnetske, James P. Mcnamara, John H. Bradford, Troy R. Brosten
Hyporheic Exchange And Water Chemistry Of Two Arctic Tundra Streams Of Contrasting Geomorphology, Morgan J. Greenwald, William B. Bowden, Michael N. Gooseff, Jay P. Zarnetske, James P. Mcnamara, John H. Bradford, Troy R. Brosten
Geosciences Faculty Publications and Presentations
The North Slope of Alaska’s Brooks Range is underlain by continuous permafrost, but an active layer of thawed sediments develops at the tundra surface and beneath streambeds during the summer, facilitating hyporheic exchange. Our goal was to understand how active layer extent and stream geomorphology influence hyporheic exchange and nutrient chemistry. We studied two arctic tundra streams of contrasting geomorphology: a high-gradient, alluvial stream with riffle-pool sequences and a low-gradient, peat-bottomed stream with large deep pools connected by deep runs. Hyporheic exchange occurred to ~50 cm beneath the alluvial streambed and to only ~15 cm beneath the peat streambed. The …
Comparison Of Instantaneous And Constant-Rate Stream Tracer Experiments Through Parametric Analysis Of Residence Time Distributions, Robert A. Payn, Michael N. Gooseff, David A. Benson, Olaf A. Cirpka, Jay P. Zarnetske, W. Breck Bowden, James P. Mcnamara, John H. Bradford
Comparison Of Instantaneous And Constant-Rate Stream Tracer Experiments Through Parametric Analysis Of Residence Time Distributions, Robert A. Payn, Michael N. Gooseff, David A. Benson, Olaf A. Cirpka, Jay P. Zarnetske, W. Breck Bowden, James P. Mcnamara, John H. Bradford
Geosciences Faculty Publications and Presentations
Artificial tracers are frequently employed to characterize solute residence times in stream systems and infer the nature of water retention. When the duration of tracer application is different between experiments, tracer breakthrough curves at downstream locations are difficult to compare directly. We explore methods for deriving stream solute residence time distributions (RTD) from tracer test data, allowing direct, non-parametric comparison of results from experiments of different durations. Paired short- and long-duration field experiments were performed using instantaneous and constant-rate tracer releases, respectively. The experiments were conducted in two study reaches that were morphologically distinct in channel structure and substrate size. …
Sediment And Nutrient Delivery From Thermokarst Features In The Foothills Of The North Slope, Alaska: Potential Impacts On Headwater Stream Ecosystems, W. B. Bowden, M. N. Gooseff, A. Balser, A. Green, B. J. Peterson, John H. Bradford
Sediment And Nutrient Delivery From Thermokarst Features In The Foothills Of The North Slope, Alaska: Potential Impacts On Headwater Stream Ecosystems, W. B. Bowden, M. N. Gooseff, A. Balser, A. Green, B. J. Peterson, John H. Bradford
CGISS Publications and Presentations
Permafrost is a defining characteristic of the Arctic environment. However, climate warming is thawing permafrost in many areas leading to failures in soil structure called thermokarst. An extensive survey of a 600 km2 area in and around the Toolik Lake Natural Research Area (TLNRA) revealed at least 34 thermokarst features, two thirds of which were new since ~1980 when a high resolution aerial survey of the area was done. Most of these thermokarst features were associated with headwater streams or lakes. We have measured significantly increased sediment and nutrient loading from thermokarst features to streams in two well-studied locations …
Analysis Of Pore Architecture And Correlation To Sonic Velocity Values In Silurian (Niagaran) Reefs Of The Michigan Basin, Amy Kathryn Noack
Analysis Of Pore Architecture And Correlation To Sonic Velocity Values In Silurian (Niagaran) Reefs Of The Michigan Basin, Amy Kathryn Noack
Masters Theses
Recent work has shown that there is a complex relationship among porosity, permeability, and rock fabric in carbonate rocks. Porosity/permeability transforms are of limited value when evaluating carbonate reservoirs because permeability is controlled by pore type. Vuggy, moldic, or fenestral pore types have high porosity but poor permeability; in contrast, intergranular and intercrystalline pore networks have high porosity and high permeability. Visible pore types of key facies in five Middle Silurian (Niagaran) Reef reservoirs of the Michigan Basin were evaluated to better understand related permeability. Image analysis was performed on key facies to understand pore geometries and pore connectivity. Facies …
Alaska's Pavlof Volcano Ends 11-Year Repose, Christopher F. Waythomas, Stephanie G. Prejean, Stephen R. Mcnutt
Alaska's Pavlof Volcano Ends 11-Year Repose, Christopher F. Waythomas, Stephanie G. Prejean, Stephen R. Mcnutt
School of Geosciences Faculty and Staff Publications
After an 11-year period of repose, Pavlof volcano on the Alaska Peninsula (Figure 1) began an episode of Strombolian eruption lasting 31 days, from 14 August to 13 September 2007.
The eruption began abruptly on 14 August after a minor increase in seismicity the previous day. Nearly continuous lava fountaining, explosions, and lahars caused by minor disruption of the ice and snow cover on the volcano characterized the eruption. The eruption also produced diffuse ash plumes that reached 5–6 kilometers above sea level, but the plumes were too small and did not extend high enough to affect local or regional …
Records Of Natural Fires And The Sorption Of Polycyclic Aromatic Hydrocarbons (Pahs) By Black Carbon And Carbon Chars In Sediments From Oriole Lake (Sequoia National Park), Kevyn Bollinger
Senior Honors Projects
This project investigates the interaction between Black Carbon and Polycyclic Aromatic Hydrocarbons (PAHs) in lake sediments from Oriole Lake in Sequoia National Park California. The interaction between Black Carbon and PAHs is of interest because little is known with respect to the availability and the time scale within which black carbon adsorbs PAHs in a natural system. Black Carbon and PAHs both will eventually be degraded in the environment but the relevant timescales of sorption and degradation are unknown. Field work for this project was conducted July 16-21, 2007 at Oriole Lake in Sequoia National Park California. Sequoia National Park …
The Analysis Of The Natural Attenuation Of Chlorinated Solvents In Groundwater At The Former Westinghouse Site In Bloomfield, New Jersey, Deborah J. Katchen
The Analysis Of The Natural Attenuation Of Chlorinated Solvents In Groundwater At The Former Westinghouse Site In Bloomfield, New Jersey, Deborah J. Katchen
Theses, Dissertations and Culminating Projects
Data for a contaminated site in Bloomfield, New Jersey were gathered from the New Jersey Department of Environmental Protection (NJDEP), in order to evaluate the hydrogeological conditions at the site. In particular, the data were analyzed to determine whether: 1) the site is still significantly contaminated, 2) natural attenuation is occurring at the site, and 3) natural attenuation will completely remediate the site in a reasonable period of time. The occurrence and distribution of Trichloroethene (TCE) and its daughter products, Dichloroethene (cis 1,2 DCE) and Vinyl Chloride (VC) show that the site is still contaminated.
It was observed that the …
A Post-Project Assessment Of The Provo River Restoration Project: Channel Design, Reconfiguration, And The Re-Establishment Of Critical Physical Processes, Randy Ray Goetz
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
A physical assessment of the Provo River Restoration Project was undertaken in order to determine how alterations to the channel were designed, the nature of as-built channel morphology, and the performance of the reconfigured channel in terms of achieving frequent (2-year recurrence) bankfull discharge and increasing transient storage. Measures of channelized and reconfigured channel morphology were obtained using total station survey, digital aerial photography, and pebble counts. Results of geomorphic analysis were compared with similar measurements made by a regional consulting company, and stream channel design data, in order to determine that intended mitigation included reducing channel capacity, increasing sinuosity, …
Modern Nutrient Limitation And Geologic Record Of Organic Matter Sources In The Bioluminescent Bays Of Vieques, Puerto Rico, Erin Algeo
Earth and Environmental Geosciences Student Honors Theses
The factors contributing to the success of the bioluminescent dinoflagellate, Pyrodinium bahamense var. bahamense in the bays of Vieques, Puerto Rico, are not fully understood, although the dinoflagellate’s success is closely tied to its environment and the nutrients within that environment. Exploring the present and past nutrient concentrations and sources of organic material within the bioluminescent bays of Vieques assists in determining the status of and potential threat to the population of Pyrodinium bahamense var. bahamense. Modern carbon, nitrogen, and phosphorus nutrient concentrations were measured, primarily in the seagrass Thalassia testudinum, to evaluate the distribution and potential limitation of those …
Provenance Analysis Of The Cretaceous Hornbrook Formation Of Northern California And Southern Oregon, Emily J. Beverly
Provenance Analysis Of The Cretaceous Hornbrook Formation Of Northern California And Southern Oregon, Emily J. Beverly
Earth and Environmental Geosciences Student Honors Theses
The provenance of the Cretaceous Hornbrook Formation, deposited unconformably on the eastern terranes of the Klamath Mountains of northern California and southern Oregon, may prove critical to reconstructing the complex Cretaceous paleogeography of this region. Sandstone petrography from each of the five members of the Hornbrook Formation indicates a variable source region with elements from basement uplift, transitional continent, recycled orogen, and dissected arc sources. A conglomerate clast count from the Klamath River Conglomerate member is broadly consistent with sandstone petrography, but yielded more quartzite and fewer volcanic clasts than the sand-sized fraction. This reflects the different susceptibility to weathering …
Rapid Evolution In Introduced Species, ‘Invasive Traits’ And Recipient Communities: Challenges For Predicting Invasive Potential, Kenneth D. Whitney, Christopher A. Gabler
Rapid Evolution In Introduced Species, ‘Invasive Traits’ And Recipient Communities: Challenges For Predicting Invasive Potential, Kenneth D. Whitney, Christopher A. Gabler
School of Earth, Environmental, & Marine Sciences Faculty Publications
The damaging effects of invasive organisms have triggered the development of Invasive Species Predictive Schemes (ISPS). These schemes evaluate biological and historical characteristics of species and prioritize those that should be the focus of exclusion, quarantine, and/or control. However, it is not clear how commonly these schemes take microevolutionary considerations into account. We review the recent literature and find that rapid evolutionary changes are common during invasions. These evolutionary changes include rapid adaptation of invaders to new environments, effects of hybridization, and evolution in recipient communities. Strikingly, we document 38 species in which the specific traits commonly associated with invasive …
Pesticides In Rain In Four Agricultural Watersheds In The United States, Jason R. Vogel, Michael S. Majewski, Paul D. Capel
Pesticides In Rain In Four Agricultural Watersheds In The United States, Jason R. Vogel, Michael S. Majewski, Paul D. Capel
United States Geological Survey: Staff Publications
Rainfall samples were collected during the 2003 and 2004 growing seasons at four agricultural locales across the USA in Maryland, Indiana, Nebraska, and California. The samples were analyzed for 21 insecticides, 18 herbicides, three fungicides, and 40 pesticide degradates. Data from all sites combined show that 7 of the 10 most frequently detected pesticides were herbicides, with atrazine (70%) and metolachlor (83%) detected at every site. Dacthal, acetochlor, simazine, alachlor, and pendimethalin were detected in more than 50% of the samples. Chlorpyrifos, carbaryl, and diazinon were the only insecticides among the 10 most frequently detected compounds. Of the remaining pesticide …
Transport And Fate Of Nitrate At The Ground-Water/Surface-Water Interface, Larry J. Puckett, Celia Zamora, Hedeff Essaid, John T. Wilson, Henry M. Johnson, Michael Brayton, Jason R. Vogel
Transport And Fate Of Nitrate At The Ground-Water/Surface-Water Interface, Larry J. Puckett, Celia Zamora, Hedeff Essaid, John T. Wilson, Henry M. Johnson, Michael Brayton, Jason R. Vogel
United States Geological Survey: Staff Publications
Although numerous studies of hyporheic exchange and denitrification have been conducted in pristine, high-gradient streams, few studies of this type have been conducted in nutrient-rich, low-gradient streams. This is a particularly important subject given the interest in nitrogen (N) inputs to the Gulf of Mexico and other eutrophic aquatic systems. A combination of hydrologic, mineralogical, chemical, dissolved gas, and isotopic data were used to determine the processes controlling transport and fate of 3− in streambeds at five sites across the USA. Water samples were collected from streambeds at depths ranging from 0.3 to 3 m at three to five …