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.
Results
Showing 1 to 20 of 90 for “"nitrogen cycle"”.
-
Soil carbon and nitrogen cycle modeling for bioenergy crops
… the expansion of these crops on soil carbon and nitrogen dynamics is integral to understanding their long-term environmental impacts. We developed a coupled hydrological-soil nutrient model under identical field conditions and different harvest litter input scenarios. Our project simulation shows …
-
Voltammetric and spectroscopic insights into electrochemical nitrogen-cycle transformations
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-08-01
-
The nitrogen cycle and ecohydrology of seasonally dry grasslands
… of ecosystem traits with the water, carbon, and nitrogen cycles. Observations from a factorial irrigation-fertilization experiment in a seasonally dry annual grassland are combined with a simple ecosystem model to identify relationships between vegetation, nitrogen availability, and hydrology. …
-
Nitrogen-cycle dynamics of a waste recycling oyster culture system.
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1978.
-
A mathematical model of the nitrogen cycle in a constructed wetland
… wetland theory to predict the fate of nitrogen runoff in a constructed wetland. The model utilizes nitrogen concentrations of influent water as system inputs. The model is three-dimensional, one dimensional in time, and two dimensional in space. The physical domain of the model …
-
A real time model of nitrogen-cycle dynamics in an estuarine system.
Thesis: Sc. D., Massachusetts Institute of Technology, Department of Civil Engineering, 1975
-
The role of denitrification in the nitrogen cycle of New England salt marshes
I used direct measurements of nitrogen gas (N2) fluxes and a 15N stable isotope tracer to determine the contribution of denitrification to salt marsh sediment N cycling. Denitrification in salt marsh tidal creekbottoms is a major sink for groundwater nitrate of terrestrial origin. I studied …
-
Role of Dissolved Organic Nitrogen in the Soil Nitrogen Cycle of Forest Ecosystems
… been shown to be a crucial part of the soil N cycle in forest ecosystems. Despite this, information on its dynamics, sources and fate is still lacking. Especially data from (sub)tropical forest ecosystems are scarce. Therefore, this study investigated (i) the magnitude and drivers of DON fluxes …
-
The role of denitrification in the nitrogen cycle of New England salt marshes
I used direct measurements of nitrogen gas (N₂ fluxes and a ¹⁵N stable isotope tracer to determine the contribution of denitrification to salt marsh sediment N cycling. Denitrification in salt marsh tidal creekbottoms is a major sink for groundwater nitrate of terrestrial origin. I studied …
-
Investigating the role of trichodesmium spp. in the oceanic nitrogen cycle through observations and models
The nitrogen fixation and abundance of Trichodesmium colonies and their connections with physical processes were investigated through Video Plankton Recorder (VPR) and other observations collected in fall 2010 and spring 2011 in the western subtropical–tropical North Atlantic. A data processing …
-
Investigating the role of Trichodesmium spp. in the oceanic nitrogen cycle through observations and models
This work concerns the nitrogen fixation and abundance of Trichodesmium colonies in the western subtropical-tropical North Atlantic and their connections with physical processes. Data were collected in fall 2010 and spring 2011, primarily using the Video Plankton Recorder (VPR). A data processing …
-
Can nitrogen isotopes be used to detect the effects of burning on nitrogen cycling? : a study on Pinus resinosa in Minnesota, USA
… and coarse roots from stands were analysed for nitrogen isotopes in an attempt to determine if fire effects nitrogen cycling. Fire increased the % nitrogen of coarse roots and changed the ratio of C: N. It may also decrease the depth of the A-horizon. It did not however affect the nitrogen …
-
Can nitrogen isotopes be used to detect the effects of burning on nitrogen cycling? A study on Pinus resinosa in Minnesota, USA
… and coarse roots from stands were analysed for nitrogen isotopes in an attempt to determine if fire effects nitrogen cycling. Fire increased the % nitrogen of coarse roots and changed the ratio of C: N. It may also decrease the depth of the A-horizon. It did not however affect the nitrogen …
-
The effects of atrazine on nitrogen cycling in a freshwater wetland microcosm
… 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 nutrients and herbicides, thus increasing nitrogen levels in non-point …
-
Holocene guano influences on eutrophication and lacustrine ecology at Kettle Lake, North Dakota
… influence of climate-forced avian migration on nitrogen cycling at Kettle Lake, North Dakota throughout the Holocene. I investigate this influence using stable nitrogen isotope values (𝛿15N) from lake sediment organic matter, with particular focus on periods of struvite deposition, a …
-
Physical and biogeochemical properties of seasonal sea ice in the Atlantic sector of the Antarctic marginal ice zone
… and thickens as a result of multiple cycles of breaking and rafting of young ice, and the biogeochemical signatures of the young ice are conserved in the reformed, consolidated ice cover. Novel nitrate and particle δ N15 measurements enabled us to investigate the seasonal evolution of …
-
Tat signal peptide recognition during protein maturation and export
Nitrogen is one of the most abundant elements on Earth and mostly found in the atmosphere as the inert gas N2. Therefore the nitrogen cycle is important for maintaining the bioavailabilty of nitrogen for organisms. Denitrification is a process that closes the nitrogen cycle by subsequent conversion …
-
The biogeochemistry of marine nitrous oxide
… In particular, human perturbation of the nitrogen cycle has increased the N2O production rates of the two major sources of this greenhouse gas, soil and the ocean. Nitrification, and particularly ammonia oxidation, is one of the major processes that produces N2O in the ocean. In this …
Page 1 of 5