Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 103 for “"Nitrogen Cycling"”.
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Microbial nitrogen cycling across coastal ecosystems
Contains fulltext : 325677.pdf (Publisher’s version ) (Open Access)
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Carbon and nitrogen cycling in vegetated coastal ecosystems
… (CH4), and nitrous oxide (N2O)) and nutrient cycling. Vegetated coastal ecosystems (e.g., mangroves, salt marshes, and seagrasses) are key drivers of coastal greenhouse gas and nutrient cycling because of their environmental characteristics (e.g., shallow depths, organic matter rich sediments, …
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Microbial community structure and nitrogen cycling in limestone biofilms
… ubiquity in central Texas and possible role in nitrogen cycling. Biofilm samples from an ornamental pond in Austin, Texas were collected over the course of two and a half years. Microscopic analysis indicated that the general physical structure of the biofilm remained constant, but the organisms …
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Microbial nitrogen-cycling and cooperation in the terrestrial subsurface
The microbial nitrogen cycle is predicted to play a major role in nitrogen transformations in the terrestrial subsurface. The cycle comprises six distinct biological N-transformation processes, including ammonification, nitrogen fixation, nitrification, denitrification, anaerobic ammonium oxidation …
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Effects of Biosolids on Carbon Sequestration and Nitrogen Cycling
… effects of biosolids on C sequestration and N cycling in the Mid-Atlantic region is not well understood. The objectives were: 1) to investigate soil C sequestration at sites with a long-term history of biosolids either in repeated application or single large application; 2) to characterize and …
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Nitrogen cycling in tall fescue turf with added clippings
… were initiated to evaluate grass clippings as a nitrogen (N) source for tall fescue (Festuca arundinacea, Schreb. Rebel’) turf, and to determine the maximum feasible loading rate of clippings onto tall fescue turf. Test plots in both studies received additional clippings from adjacent donor …
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Nitrogen cycling in young mine soils in Southwest Virginia
Deficiency of available nitrogen (N) is one of the major factors limiting the establishment of a long term self-sustaining vegetative community on mine soils. This investigation was conducted to study the nature of N form and dynamics in southwest Virginia mine soils. Fresh mine spoils contained a …
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Closing the knowledge gap surrounding nitrogen cycling in Minnesota lakes
Nitrogen (N) is an element necessary for life, but in excess quantities in aquatic systems leads to hypoxia, loss of biodiversity and harmful algal blooms. Allochthonous inputs are typically the critical drivers of eutrophication, but it is also important to understand how those inputs interact …
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A Microbial Survey of Lake Kivu: Mechanisms of Nitrogen Cycling
… OAE analogue and is used to study a proposed nitrogen cycling mechanism that could explain the characteristic 𝛿¹⁵N excursions associated with OAEs. Biomarkers are isolated from sediment samples and analyzed across depth below the lake floor. The results are consistent with a biologically …
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METHYLATED AMINE-UTILISING BACTERIA AND MICROBIAL NITROGEN CYCLING IN MOVILE CAVE
… being methylotrophic substrates, they are also a nitrogen source for many non-methylotrophic bacteria. The role of methylated amines as carbon and nitrogen sources for Movile Cave bacteria was investigated using a combination of DNA stable isotope probing and cultivation studies. Both, …
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Perennial energy crops on riparian buffers affect nitrogen cycling microbial communities
… abundances of genes encoding the enzymes of N cycling functional groups involved in ammonia oxidation (amoA), nitrite ammonification (nrfA), denitrification (nirK, nirS, norB, and nosZ), and N fixation (nifH). The results indicated that N application significantly affected the abundance of four …
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Nitrogen Cycling from Fall Applications of Biosolids to Winter Small Grains
Environmental concerns about winter nitrogen (N) leaching loss limit the amount of biosolids applied to winter small grains in Virginia. Ten field studies were established 2012-2014 in Virginia to determine the agronomic and environmental feasibility of fall biosolids applications to soft red …
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Municipal wastewater effects on nitrogen cycling in a mature hardwood forest
… forest, and their effects on forest nutrient cycling were monitored for two years. Tree growth, seedling reproduction, tree mortality, species diversity, and N sequestering by vegetation were not changed significantly. Herbaceous ground cover increased due to irrigation, except for the 140 cm …
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Coupled arsenic, iron, and nitrogen cycling in arsenic-contaminated Upper Mystic Lake
… controlling arsenic (As) remobilization and cycling in the hypolimnion of As-contaminated Upper Mystic Lake (UML; Winchester, MA). We conducted field and laboratory studies, and applied mass balance, surface complexation, and thermodynamic modeling to explore As cycling and its links to other …
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The effects of atrazine on nitrogen cycling in a freshwater wetland microcosm
… by disrupting microbial communities and nutrient cycling. The addition of atrazine to a wetland microcosm will disrupt the nitrogen cycle by inhibiting nitrifying and denitrifying bacteria. The inhibition or absence of functional groups of bacteria will limit the ability of the wetland to remove …
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CARBON AND NITROGEN CYCLING IN GIANT CANE (ARUNDINARIA GIGANTEA (WALT.) MUHL.) RIPARIAN ECOSYSTEMS
… To examine the role that cane plays in nutrient cycling and to attempt to determine targeted restoration sites, a four phase research strategy was designed to determine physical and chemical properties of existing riparian stands of native giant cane and their associated soils. Phase one was a …
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Mixed layer nitrogen cycling in the Southern Ocean: seasonality, kinetics, and biogeochemical implications
… in setting atmospheric CO2. However, active cycling of nitrogen (N) in the seasonally-varying mixed layer – including the production of ammonium and its subsequent removal via phytoplankton uptake and nitrification (i.e., the oxidation of ammonium to nitrite and then nitrate) – remains poorly …
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Hyperspectral Reflectance and Stable Isotopic Nitrogen: Tools to Assess Forest Ecosystem Nitrogen Cycling
The use of nitrogenous fertilizers in agricultural and forestry practices coupled with increased fossil fuel combustion and resulting nitrogen (N) deposition across the landscape have contributed to a near doubling of N inputs to terrestrial ecosystems. With such dramatic changes have come adverse …
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The influence of redox dynamics on nitrogen cycling and nitrous oxide emissions from soils
… denitrification) and sinks (reduction to dinitrogen). Soil volumetric water content is directly linked to dissolved oxygen and to redox potential, which regulate microbial metabolism and chemical transformations in the environment. The relationship between soil moisture and N2O is usually …
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