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Full-Text Articles in Physical Sciences and Mathematics
Sorption Of 2-Naphthalene Sulfonate To Organic Carbon In Natural Saturated Porous Media, Jiyan Hatami
Sorption Of 2-Naphthalene Sulfonate To Organic Carbon In Natural Saturated Porous Media, Jiyan Hatami
Theses and Dissertations
Organic carbon (OC) in aquifer sediments serves as a key geochemical control on contaminant fate and transport, potentially immobilizing or delaying mass transport downgradient. Quantifying the abundance of OC in aquifer sediments is therefore imperative in developing a conceptual understanding of local contaminant transport. Traditional methods involve time-intensive coring and lab analyses for total OC (TOC) at distinct intervals with depth. These methods fail to account for the heterogeneity between discrete points and do not interrogate TOC along groundwater flow pathways. 2-naphthalene sulfonate (2-NS), a novel groundwater tracer, was investigated here as a possible sorptive tracer for estimating the relative …
Endolithic Microbial Carbon Cycling In East Antarctica, Natalie Tyler
Endolithic Microbial Carbon Cycling In East Antarctica, Natalie Tyler
Theses and Dissertations
Microbes adapt to inhospitable conditions by colonizing niches that protect them from severe environmental conditions, making them model organisms in the search for life on other planets. Endoliths are globally ubiquitous microbes that colonize structural cavities within rocks, which protect them from environmental stressors while maintaining access to nutrition and light sources. Despite harsh katabatic winds, extreme temperature fluctuations, harmful UV radiation and exposure to desiccation, endolithic communities have been observed in Antarctica. Previous studies have found viable and abundant microbial biomass through microscopy and the addition of isotopic labels. However, due to the slow metabolic activity of these microbes, …
Modeling Lake Michigan Nearshore Carbon And Phosphorus Dynamics, Joseph Henry Fillingham
Modeling Lake Michigan Nearshore Carbon And Phosphorus Dynamics, Joseph Henry Fillingham
Theses and Dissertations
Dreissenid mussels, in particular quagga mussels (Dreissena rostiformis bugensis), are transforming the Lake Michigan ecosystem by clearing the water column, recycling phosphorus and modifying benthic habitat. These impacts are thought to have caused observed declines in the spring phytoplankton bloom in Lake Michigan, as well as changes to food web structure and declines in the abundance of critical invertebrate and fish species. In the nearshore zone, the resurgence of benthic Cladophora algae to nuisance levels not observed since phosphorus loading abatement policies instituted in the 1970s has also been attributed to water column clearing and phosphorus recycling by mussels. Using …
Stoichiometric Controls On Denitrification In High Nitrate Watersheds, Brian Grebliunas
Stoichiometric Controls On Denitrification In High Nitrate Watersheds, Brian Grebliunas
Theses and Dissertations
Watershed biogeochemistry throughout Midwestern agroecosystems have been altered through hydrologic manipulation and over-application of nitrogenous fertilizers. As a result, nitrate (NO3-N) export from subsurface drainage has negative impacts on local and downstream ecosystem health. Wetland installation has proven to be a viable option for targeted management where a large proportion of NO3-N is removed through the bacterially mediated process denitrification. For denitrification to maintain high rates under prolonged NO3-N saturation, a stable supply of labile dissolved organic carbon (DOC) is required. The focus of this dissertation was to study how the stoichiometry of agricultural wetlands limits denitrification within a controlled …