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Articles 1 - 26 of 26
Full-Text Articles in Life Sciences
Investigating The Role Of Plant Traits And Interactions In Emergent Wetland Nutrient Removal, Andrew Ryan Sample
Investigating The Role Of Plant Traits And Interactions In Emergent Wetland Nutrient Removal, Andrew Ryan Sample
Theses and Dissertations
Increasing wetland restoration in the Lower Mississippi Alluvial Valley has been identified as a method to reduce nutrient loading in the Gulf of Mexico. Wetlands have historically been used to treat water through processes facilitated by wetland plants, and relatively few species and plant traits have been identified as important in carrying out these processes. This study focuses on some of those species and traits and aims to identify species differences and plant traits that may be important for wetland nutrient mitigation. Chapter I provides background information on nutrient pollution, wetland biogeochemical mechanisms for nutrient sequestration, and the focal species …
Nutrient Dynamics Of Freshwater Estuarine Sediments Disturbed By Dredging, Ryan Allan John Roekle
Nutrient Dynamics Of Freshwater Estuarine Sediments Disturbed By Dredging, Ryan Allan John Roekle
Theses and Dissertations
This study examined the nutrient environment of sediments in the Milwaukee River estuary and the dynamics of those nutrients during simulated disturbance experiments within the context of large-scale dredging remediation. Surface sediments were collected from throughout the Milwaukee estuary (including river, harbor, and nearshore stations) by PONAR, centrifuged to separate porewater (interstitial water) from solid material, and filtered to further isolate and stabilize dissolved material. Porewaters were analyzed for dissolved nutrients including ammoniacal nitrogen (AN), nitrate, nitrite, and soluble reactive phosphorus (SRP). Surface sediment porewaters within the estuary were often highly enriched in AN and SRP, which were often 10-2000x …
An Evaluation On The Effects Of Additions And Deletions Of Specific Nutrient Management Strategies On Corn Yield At Different Plant Densities, James D. Dew
Theses and Dissertations
Improved management strategies are needed to increase yield production and quality. The study aimed to determine suitable cultural practices for improved corn production. Experiments were set up at Verona and Stoneville, Mississippi, from 2020 to 2022. Treatments included row configurations (single and twin-row), plant populations (79,000 and 99,000 seeds ha-1), and six combinations of nutrients with or without fungicide. The nutrients evaluated were two nitrogen rates 235 and 314 kg N ha-1, phosphorus 45 kg P ha-1, potassium 112 kg K ha-1, sulfur 22 kg S ha-1, and zinc 11 kg Zn ha-1, and fungicide at 272 ml ha-1. In …
Climate Change And The Global Nutrient Overload: The Microbial Response Of Extreme Waterbodies To Environmental Change, Samuel P. Bratsman
Climate Change And The Global Nutrient Overload: The Microbial Response Of Extreme Waterbodies To Environmental Change, Samuel P. Bratsman
Theses and Dissertations
One of the defining characteristics of our current epoch—the Anthropocene—is modification of nutrient cycles. At regional to global scales, humans have fundamentally reshaped the availability of carbon, nitrogen, and phosphorus. These changes are particularly apparent in freshwater ecosystems, which receive surface and groundwater inputs of nutrients from agriculture, fossil fuel use, and wastewater. In this thesis, I investigated how the addition of nutrients affects microbial community and biogeochemistry in two extreme environments: the hypereutrophic shallow Utah Lake and nutrient-limited Arctic permafrost streams. In my first chapter, I used bioassay and dilution bioassay experiments to identify what factors control harmful algal …
Transport And Fate Of Phosphorus In The Nearshore Zone Of Lake Michigan, Nathan Van Ee
Transport And Fate Of Phosphorus In The Nearshore Zone Of Lake Michigan, Nathan Van Ee
Theses and Dissertations
Bioavailable phosphorus loads exported to Lake Michigan from the Milwaukee and Sheboygan River Watersheds appear to have increased in the last 40 years despite meeting total phosphorus (TP) loading goals set by the Great Lakes Water Quality Agreement (GLWQA).Overall, bioavailability of P delivered from the Milwaukee and Sheboygan Rivers was highest during the warmer months, which coincides with the nearshore nuisance algae growth season. However, first order loss rates of SRP calculated during baseflow recession were also greatest during the summer, suggesting that increased river residence time during the summer could reduce export of bioavailable P. Observations of phosphorus partitioning …
Quagga Mussel Induced Phosphorus Cycling Changes In Lake Michigan, Rae-Ann Maclellan-Hurd
Quagga Mussel Induced Phosphorus Cycling Changes In Lake Michigan, Rae-Ann Maclellan-Hurd
Theses and Dissertations
Quagga mussels (Dreissena rostriformis bugensis) are an invasive ecosystem engineer that have successfully colonized both profundal and nearshore regions in Southern Lake Michigan. Quagga mussels directly altered the flow of nutrients by filtering particles, excretion of soluble forms of nutrients in the benthos, and through the production of biodeposits. Mussel excretion, egestion, and capture rates of P were compared between a 25 meter and a 55 meter deep site near Milwaukee Harbor to determine the retention of nutrients in these regions. The capture rate of particulate phosphorus at the 25m site (278 ± 388 μmol m-2) was similar to that …
Nutrient Limitation Of Phytoplankton In Lake Wateree, South Carolina: Implications For Future Water Quality Management, Kara M. Clyburn
Nutrient Limitation Of Phytoplankton In Lake Wateree, South Carolina: Implications For Future Water Quality Management, Kara M. Clyburn
Theses and Dissertations
Cultural eutrophication is a primary contributor to phytoplankton production in freshwater lakes from excess anthropogenic nutrient inputs, and resulting impacts on water quality, aquatic ecosystems, human and animal health are increasing worldwide. Understanding the factors that limit phytoplankton growth is an important strategy for identifying and managing nutrient sources and successfully controlling the over- enrichment of nitrogen (N) and/or phosphorus (P) in freshwater lakes. The Redfield molecular ratio of carbon (C), N and P maintains that the C:N:P molar ratio is 106:16:1 when nutrients are not limiting, and the ecosystem is balanced. A N:P molar ratio > 20:1 tends to be …
Evaluating The Evidence And Assessing Registered Dietitian Nutritionists' Perceptions Of The Complex Renal Dietary Restrictions, Alyssa Lee Welte
Evaluating The Evidence And Assessing Registered Dietitian Nutritionists' Perceptions Of The Complex Renal Dietary Restrictions, Alyssa Lee Welte
Theses and Dissertations
The renal diet is often regarded as challenging to teach and follow, and can easily lead to additional complications, including malnutrition. Recent trends in the literature have suggested a liberalization in the renal diet, though no studies have assessed whether Registered Dietitian Nutritionists (RDNs) are comfortable making this change. An original, cross-sectional survey was created for this study. 187 renal dietitians completed the survey which revealed that only 15.3% of participants felt it is acceptable to liberalize the standard dietary restriction on fruits and vegetables, and 13.6% said the same about the bean and legume restriction. 19.9% are extremely likely …
Assessing Phosphorus Sources With A Gis-Based Phosphorus Risk Index In A Mixed-Use, Montane Watershed, Josiah A. Johns
Assessing Phosphorus Sources With A Gis-Based Phosphorus Risk Index In A Mixed-Use, Montane Watershed, Josiah A. Johns
Theses and Dissertations
Elevated phosphorus (P) loading of freshwater lakes and reservoirs often results in poor water quality and negative ecological effects. Critical source areas (CSA) of P in the watershed can be difficult to identify and control. A useful concept for identification of a CSA is the P risk index (P Index) that evaluates the P risk associated with distinct source and transport pathways. The objectives of this study were to create a GIS model that adapts the Minnesota (MN) P Index for use at the watershed scale in a mixed-use, mountain environment, and to evaluate its effectiveness relative to field-based assessment. …
Assessing Phosphorus Sources With Synoptic Sampling In The Surface Waters Of A Mixed-Use, Montane Watershed, Austin Willis Pearce
Assessing Phosphorus Sources With Synoptic Sampling In The Surface Waters Of A Mixed-Use, Montane Watershed, Austin Willis Pearce
Theses and Dissertations
Few elements in surface waters are monitored as closely as phosphorus (P) due to its role in the eutrophication and degradation of surface waters. Limiting P mobilization from source areas is, therefore, a central goal of water quality protection plans. But the work of locating sources in mixed-use watersheds is challenged by the spatial and temporal variability of critical source areas (CSAs) of P. Synoptic sampling is a proven method for capturing the spatial variation of water quality parameters in surface waters, though it's not often used to track temporal dynamics across the same study area. Phosphorus fractionation is an …
Nutrient Loading Reduction In A Tile Drained Agricultural Watershed Through Watershed-Scale Cover Cropping: A High Resolution Analysis, Benjamin Gerald Bruening
Nutrient Loading Reduction In A Tile Drained Agricultural Watershed Through Watershed-Scale Cover Cropping: A High Resolution Analysis, Benjamin Gerald Bruening
Theses and Dissertations
Nutrient pollution originating from agricultural regions in the Midwest is a serious issue, leading to pollution of drinking water sources as well as large hypoxic zones in the Gulf of Mexico. The source of much of this contamination has been shown to be runoff from agricultural fields in the Upper Mississippi River Basin. One method that has been shown to reduce this pollution from the Upper Mississippi River Basin is the planting of winter cover crops. Winter cover crops such as rye and tillage radish have been shown to significantly reduce nitrate exported from agricultural fields, even in tile-drained watersheds …
The Effect Of Chronic Nutrient Addition From Wastewater On Forest Ecosystems At The Rice Rivers Center, Michael Beck
The Effect Of Chronic Nutrient Addition From Wastewater On Forest Ecosystems At The Rice Rivers Center, Michael Beck
Theses and Dissertations
Wastewater application to land can be a useful tool for mitigating impacts of nutrient enrichment on aquatic systems. A land application treatment system at VCU’s Rice Rivers Center in Charles City County, VA provided an opportunity to study the impact of wastewater addition on the biogeochemistry of forests representative of the Mid-Atlantic Coastal Plain. Nutrient concentrations in throughfall and leachate were measured at Treatment and Control sites to assess differences in nutrient deposition and retention. Wastewater amended plots from the Walter L. Rice education building received 20-fold (N) and 6-fold (P) higher inputs relative to Control plots and plots located …
Marine Phosphorus Biogeochemistry Ecological Insights From Analytical Chemistry, Douglas W. Bell
Marine Phosphorus Biogeochemistry Ecological Insights From Analytical Chemistry, Douglas W. Bell
Theses and Dissertations
The supply of phosphorus (P) directly impacts the growth and speciation of marine microbes (i.e., phytoplankton, bacteria, Archaea). In turn, microbial communities shape the magnitude and rate of marine biogeochemical cycles, ultimately affecting global climate and food production. This dynamic reflects the continuum of temporal and spatial scales at which the marine P cycle operates. However, linking multiple scales of cycling remains a consistent challenge. The primary objective of my dissertation was to gain insight into marine P biogeochemistry, by means of analytical chemistry, at the molecular and environmental scales of cycling. The first component of my research was to …
Effect Of Cover Crops And Nitrogen Application Timing On Nutrient Loading And Concentration Through Subsurface Tile Drainage, Michael Douglas Ruffatti
Effect Of Cover Crops And Nitrogen Application Timing On Nutrient Loading And Concentration Through Subsurface Tile Drainage, Michael Douglas Ruffatti
Theses and Dissertations
It has been estimated that nitrate (NO3-N) leaching from artificially drained agricultural fields in the Upper Mississippi River Basin accounts for approximately 65% of nitrogen (N) delivered annually to the Gulf of Mexico. Therefore, the objectives of this study were to investigate the impact fertilizer application timing and cover crops (CC) adoption on the load and concentration of nutrients in subsurface drainage leachate. This experiment was conducted at the Illinois State University Nitrogen Management Field Station, in Lexington, IL. Treatments include a zero control (no N fertilizer and no cover crop), fall dominated N application (70% fall, 30% spring) with …
Deficient, Adequate And Excess Nitrogen, Phosphorus, And Potassium Growth Curves Established In Hydroponics For Biotic And Abiotic Stress-Interaction Studies In Lettuce, Douglas Keith Jacobson
Deficient, Adequate And Excess Nitrogen, Phosphorus, And Potassium Growth Curves Established In Hydroponics For Biotic And Abiotic Stress-Interaction Studies In Lettuce, Douglas Keith Jacobson
Theses and Dissertations
Mineral nutrients have marked effects on plant health by providing the building blocks for plant growth, as well as for mitigating abiotic and biotic stress factors, particularly disease development. Even if mineral nutrition field studies are conducted to study pest management, they are at the mercy of complex soil, water, and climatic conditions not amenable to strict experimental control. Therefore, a hydroponic method of growing lettuce was developed and growth curves were established for the macronutrients nitrogen (N), phosphorus (P), and potassium (K). Lettuce plants were grown at varying levels of each nutrient: 2.5, 5, 10, 20, 40, 80, 160, …
Importance Of Placement Depth In Evaluating Soil Nitrogen, Phosphorus, And Sulfur Using Ion Exchange Resin Capsules In Semi-Arid, Low Fertility Soils, Rachel Lynn Buck
Importance Of Placement Depth In Evaluating Soil Nitrogen, Phosphorus, And Sulfur Using Ion Exchange Resin Capsules In Semi-Arid, Low Fertility Soils, Rachel Lynn Buck
Theses and Dissertations
Ion exchange resin capsules provide a possible alternative to conventional soil testing procedures. Previous studies with semi-arid, low fertility soils observed poor relationships with poorly mobile nutrients such as phosphorus (P). We propose that placement depth may improve those relationships. Our objective was to (1) determine if placement depth could improve resin capsule estimation of the bioavailability of nitrogen (N), P, and sulfur (S) and (2) to determine if resin capsules can effectively estimate S availability in semi-arid, low fertility soils. Field sites were established in Rush and Skull Valleys, Utah on loam and sandy loam soils, respectively. Fertilizer was …
Hypersaline Lake Environments Exhibit Reduced Microbial Dormancy, Joshua Christopher Vert
Hypersaline Lake Environments Exhibit Reduced Microbial Dormancy, Joshua Christopher Vert
Theses and Dissertations
From acid seeps and deep-sea thermal vents to glacial ice and hypersaline lakes, extreme environments contain relatively simplified communities consisting of extremophiles that have evolved to survive and thrive under adverse abiotic conditions. In more neutral environments, microorganisms use dormancy as a common life history strategy to weather temporal fluctuations of resources or stresses until more 'optimal' conditions are present. It is unclear if dormancy is an essential survival mechanism for microorganisms in extreme environments; however, recent studies suggest that extreme environments may create stable conditions for extremophiles to the extent that dormancy is of less ecological importance. Using lake …
Microbial Responses To Coarse Woody Debris In Juniperus And Pinus Woodlands, Deborah Monique Rigby
Microbial Responses To Coarse Woody Debris In Juniperus And Pinus Woodlands, Deborah Monique Rigby
Theses and Dissertations
The ecological significance of coarse woody debris (CWD) is usually highlighted in forests where CWD constitutes much of an ecosystem's carbon (C) source and stores. However, a unique addition of CWD is occurring in semi-deserts for which there is no ecological analog. To stem catastrophic wildfires and create firebreaks, whole Juniperus osteosperma (Torr.) and Pinus edulis (Engelm.) trees are being mechanically shredded into CWD fragments and deposited on soils previously exposed to decades of tree-induced changes that encourage "tree islands of fertility." To investigate consequences of CWD on C and nitrogen (N) cycling, we evaluated microbial metabolic activity and N …
Improving Phosphorus Use Efficiency Through Organically Bonded Phosphorus, Micheal W. Hill
Improving Phosphorus Use Efficiency Through Organically Bonded Phosphorus, Micheal W. Hill
Theses and Dissertations
Current maximum efficiency of phosphorus (P) fertilizers that is utilized by plants in the same year of application ranges from near zero to thirty percent. Despite low utilization of P in crop production, yields are often limited by P deficiencies. Innovative technology is requisite to achieve greater efficiency as fertilizer demands are increasing, while phosphorus mineral resources are rapidly being depleted. A growing environmental concern for nutrient pollution of surface waters also carries significant weight. A novel new product, Carbond® P, is promising technology to increase P use efficiency. Research is needed to understand its capabilities and the functioning mechanisms …
Geochemical Analysis Of Ancient Activities At Two Plazas In Cobá, Mexico, Eric G. Coronel
Geochemical Analysis Of Ancient Activities At Two Plazas In Cobá, Mexico, Eric G. Coronel
Theses and Dissertations
Two plazas at Cobá, Mexico, may have been the place of market activity during the classic Maya period. The intense decomposition in the warm, moist soils of the Yucatan Peninsula precludes the identification of organic artifacts in archaeological contexts, but phosphorus and trace elements accumulation in soils may provide evidence of marketing activities. The spatial patterns of P and trace element concentrations were used to elucidate the types of ancient Maya activities that took place in those plazas. Phosphorus concentrations are highly correlated (p-value <0.01) with Fe, Mn, and Zn levels in both Plaza B and D. Although the soil geochemistry of Plaza B does not show a marketplace pattern in comparison with previous studies, the elemental concentrations and distributions within Plaza D join other lines of evidence to support the premise that marketplace activities took place at that location. Soil samples were analyzed using DTPA extraction, Mehlich II, Olsen, and Portable X-Ray Fluorescence (PXRF). Experiments were performed to study the suitability of PXRF for field studies. Aspects that were studied include granule size, soil moisture content, protective plastic films that could interfere with the X-Ray signal when placing the samples on top of the analyzer, and a comparison of certified soil standards to the PXRF elemental concentration readings. The results suggest that a field laboratory could be set up to air-dry and sieve soil samples to a minimum mesh size of #10 (> 2 mm).
Legacy Sediments In Streams - Effects On Nutrient Partitioning During Simulated Re-Suspension Events., Molly Sobotka
Legacy Sediments In Streams - Effects On Nutrient Partitioning During Simulated Re-Suspension Events., Molly Sobotka
Theses and Dissertations
Anthropogenic inputs of nutrients and sediment are a widespread problem in U.S. streams causing localized impairment and contributing to eutrophication of coastal habitats. Sediments and dissolved nutrients interact through diverse processes including ion exchange, sorption and biotic assimilation by particle-bound bacteria. This study examined the effects of sediment re-suspension on nutrient partitioning in lab microcosms using fine benthic matter collected from two Virginia Coastal Plain streams. Kimages Creek was recently restored following dam removal and was characterized by large deposits of legacy sediments. Courthouse Creek was characterized by sandy substrates typical of Coastal Plain streams. Sediment characteristics differed between the …
Evaluating Nutrient Availability In Low Fertility Soils With Resin Capsules And Conventional Soil Tests, Mary Pletsch Jones
Evaluating Nutrient Availability In Low Fertility Soils With Resin Capsules And Conventional Soil Tests, Mary Pletsch Jones
Theses and Dissertations
Commonly used soil analysis and resin capsule procedures are used to assess nutrient status in fertile soils, but their validity in semi-arid ecosystems is unknown. Three studies were performed to assess resin capsule effectiveness in semi-arid ecosystems. An incubation study was completed in which loamy sand and sandy clay loam soils were treated with rates of N, P, Fe and Zn. Each soil treatment was implanted with a resin capsule and incubated for 60 or 120 days. Resin capsules reflected NH4-N and P fertilizer at low rates in the loamy sand. NO3-N reflected rates in both soils, but did not …
Geochemical Analysis Of Ancient Fremont Activity Areas At Wolf Village, Utah, Laura Morrison Pyper
Geochemical Analysis Of Ancient Fremont Activity Areas At Wolf Village, Utah, Laura Morrison Pyper
Theses and Dissertations
There is growing interest in the use of geochemical analyses for the evaluation of anthropogenically altered soils and other archaeological deposits. Areas of human habitation and activity tend to accumulate greater levels of soil phosphorus and trace metals. These elevated concentrations leave permanent signatures that can only be removed by erosion of the soil itself, and so phosphorus and trace metal mapping have become popular field procedures to identify areas of habitation and activity. Gridded soil samples were collected and soil phosphate and trace metal ions were extracted to identify these activity areas at the ancient Fremont site Wolf Village …
The Dirt On The Ancient Maya: Soil Chemical Investigations Of Ancient Maya Marketplaces, Daniel Aaron Bair
The Dirt On The Ancient Maya: Soil Chemical Investigations Of Ancient Maya Marketplaces, Daniel Aaron Bair
Theses and Dissertations
Various criteria or lines of evidence have been used to identify ancient Maya marketplaces, including location near trade routes, artifactual evidence of trade, open space adjacent to transportation routes, proximity to public structures, low platforms and rock alignments to denote market spaces, and regular patterns in soil and floor chemical concentrations. Seibal and Mayapán were important economic Maya polities controlling the trade routes at the apex of their civilizations. The objectives of these studies were to apply geochemical and geospatial analyses of the soils and floors from public plazas and household patios, to discover the anthropogenic chemical residues of phosphorus …
Using A Chelator-Buffered Nutrient System To Study Phosphorus, Manganese And Zinc Interactions In Russet Burbank Potato, Steven A. Barben
Using A Chelator-Buffered Nutrient System To Study Phosphorus, Manganese And Zinc Interactions In Russet Burbank Potato, Steven A. Barben
Theses and Dissertations
Potato production requires high phosphorus (P) application with potential negative environmental or nutritional consequences for potato as well as for subsequent crops. Impacts of high available P on yield and plant nutrition of species in potato cropping rotations are inadequately understood, and could result in antagonistic interactions with cationic micronutrients such as zinc (Zn) and manganese (Mn). Three hydroponic experiments were conducted with Russet Burbank potato to elucidate P and Zn relationships and associated interactions with other nutrients. In the first experiment, P solution concentration was constant at 256 µM while Zn concentration varied: 0.1, 2, 6, 18, 54, 162 …
Pressurized Hot Water: An Alternative Method Of Nutrient Extraction And Subsequent Analysis For Use In Small-Scale Agriculture, Kristy Susanne Crane
Pressurized Hot Water: An Alternative Method Of Nutrient Extraction And Subsequent Analysis For Use In Small-Scale Agriculture, Kristy Susanne Crane
Theses and Dissertations
Soil analysis for small acreage farms in developing countries is often inconvenient and prohibitively expensive using current procedures, yet the information gained from these soil tests could have economical and environmental benefits. The pressurized hot-water (PHW) extraction coupled with colorimetric or turbidimetric analyses shows promise as an alternative to current procedures. Accepted methods of colorimetric analysis for NO3-N and P exist but an alternative method to atomic absorption spectrometry for K analysis is needed. Of the many possible methods to quantify K, tests performed in the Brigham Young University (BYU) laboratory found sodium tetraphenylborate to be unsatisfactory and sodium cobaltinitrite …