Methylmecury Production In Two Northern Fen Peatlands, 2017 The University of Western Ontario
Methylmecury Production In Two Northern Fen Peatlands, Mikhail J. Mack
Electronic Thesis and Dissertation Repository
Northern peatlands provide conditions favourable for sulphate reducing bacteria, microorganisms responsible for producing methylmercury, an aquatic pollutant. An expected climate driven shift from moss- to sedge-dominance may alter mercury biogeochemistry. Observations from a moss-dominated poor fen and sedge-dominated intermediate fen were used to compare methylmercury to assess if contrasting plant communities, nutrients status and/or hydrologic regime control production. Chapter 2 compared porewater methylmercury and ancillary chemistry across two Northern Ontario fens. The lower water table, greater dissolved organic carbon, and lower pH in the poor fen resulted in 3.1 times greater methylmercury. Chapter 3, riparian zones in intermediate ...
Influence Of Common Bean (Phaseolus Vulgaris) Grown In Elevated Co2 On Apatite Dissolution, 2017 University of Maine
Influence Of Common Bean (Phaseolus Vulgaris) Grown In Elevated Co2 On Apatite Dissolution, Brian Matthew Morra
Electronic Theses and Dissertations
Elevated concentrations of atmospheric CO2 brought about by human activity creates changes in plant morphology, growth rate and exudate production. Our study sought to understand the effect of these changes on soil mineral weathering using plants grown under two conditions, ambient CO2 (400ppm) and elevated CO2 (1000ppm). Phaseolus vulgaris (common beans) were grown in flow-through microcosms consisting of a mixture of quartz and apatite sands. Plant growth was sustained by a nutrient solution devoid of calcium (Ca) and phosphorous (P). Using Atomic Adsorption Spectroscopy and colorimetry, Ca and P content of the leachate and plant tissue served ...
Determining Sources Of Nitrate In The Semi-Arid Rio Grande Using Nitrogen And Oxygen Isotopes, 2017 University of Tennessee, Knoxville
Determining Sources Of Nitrate In The Semi-Arid Rio Grande Using Nitrogen And Oxygen Isotopes, Diego Alberto Sanchez Hernandez
The Rio Grande, a semi-arid river in the American Southwest, is a major source of surface water for agriculture and drinking supplies in New Mexico and Texas. In addition to increasing salinity, considerable increases of NO3- [nitrate] have been observed in the semi-arid portion of the Rio Grande. It is possible that elevated water salinity inhibits denitrification on irrigated fields and, thus, fails to mediate excess nutrient load from anthropogenic activities. Therefore, two major goals of this project were to 1) characterize and quantify major NO3- sources, and 2) assess whether elevated water salinity affects microbial denitrification. In ...
Influence Of Algae On Soil Saturated Hydraulic Conductivity: An In Situ Treatment Option For Reducing Infiltration Beneath Unlined Algae Cultivation Ponds, 2017 University of Tennessee, Knoxville
Influence Of Algae On Soil Saturated Hydraulic Conductivity: An In Situ Treatment Option For Reducing Infiltration Beneath Unlined Algae Cultivation Ponds, Molly Brianne Pattullo
Commercial production of algal biofuels is currently limited by high capital costs, including the cost of installation and maintenance of plastic pond liners, which mitigate seepage of cultivation fluids and control the release of salts and nutrients into the subsurface beneath outdoor algae cultivation ponds. However, studies of animal waste settling lagoons show that underlying soils ranging from sands to clay loams can exhibit reduced hydraulic conductivity within days to weeks after construction, reducing the need for plastic liners. The mechanisms of the hydraulic conductivity reductions, or “soil sealing”, are physical rearrangement of soil particles, buildup of fines, and the ...
Catalyzed Synthesis Of Zinc Clays By Prebiotic Central Metabolites, 2017 University of Kentucky
Catalyzed Synthesis Of Zinc Clays By Prebiotic Central Metabolites, Marcelo I. Guzman, Ruixin Zhou, Kaustuv Basu, Hyman Hartman, Christopher J. Matocha, S. Kelly Sears, Hajatollah Vali
Chemistry Faculty Publications
How primordial metabolic networks such as the reverse tricarboxylic acid (rTCA) cycle and clay mineral catalysts coevolved remains a mystery in the puzzle to understand the origin of life. While prebiotic reactions from the rTCA cycle were accomplished via photochemistry on semiconductor minerals, the synthesis of clays was demonstrated at low temperature and ambient pressure catalyzed by oxalate. Herein, the crystallization of clay minerals is catalyzed by succinate, an example of a photoproduced intermediate from central metabolism. The experiments connect the synthesis of sauconite, a model for clay minerals, to prebiotic photochemistry. We report the temperature, pH, and concentration dependence ...
A Model Archive For A Coupled Hydrodynamic-Sediment Transport-Biogeochemistry Model For The Rhône River Sub-Aqueous Delta, France, 2017 College of William and Mary
A Model Archive For A Coupled Hydrodynamic-Sediment Transport-Biogeochemistry Model For The Rhône River Sub-Aqueous Delta, France, Julia Moriarty, Courtney K. Harris, Katja Fennel, Kehui Xu, Christophe Rabouille, Marjorie A.M. Friedrichs
This dataset includes model input, code, and output used in the publication Moriarty et al. (2017, Biogeosciences), which used a coupled hydrodynamic-sediment transport-biogeochemical model to investigate the roles of resuspension, diffusion and biogeochemical processes on oxygen dynamics on the Rhône River sub-aqueous delta, France. Model development for this project focused on coupling the sediment transport and water-column biogeochemistry modules in the Regional Ocean Modeling System (ROMS) by incorporating a seabed biogeochemistry module into the ROMS framework. As described in Moriarty et al. (2017, Biogeosciences), the coupled model can account for diffusion of nutrients across the seabed-water-column interface; storage of particulate ...
Iron Addition To Soil Specifically Stabilized Lignin, 2017 Iowa State University
Iron Addition To Soil Specifically Stabilized Lignin, Steven J. Hall, Whendee L. Silver, Vitaliy I. Timokhin, Kenneth E. Hammel
Steven J. Hall
The importance of lignin as a recalcitrant constituent of soil organic matter (SOM) remains contested. Associations with iron (Fe) oxides have been proposed to specifically protect lignin from decomposition, but impacts of Fe-lignin interactions on mineralization rates remain unclear. Oxygen (O2) fluctuations characteristic of humid tropical soils drive reductive Fe dissolution and precipitation, facilitating multiple types of Fe-lignin interactions that could variably decompose or protect lignin. We tested impacts of Fe addition on 13C methoxyl-labeled lignin mineralization in soils that were exposed to static or fluctuating O2. Iron addition suppressed lignin mineralization to 21% of controls, regardless ...
Multiple Metabolisms Constrain The Anaerobic Nitrite Budget In The Eastern Tropical South Pacific, 2017 Old Dominion University
Multiple Metabolisms Constrain The Anaerobic Nitrite Budget In The Eastern Tropical South Pacific, Andrew R. Babbin, Brian D. Peters, Calvin W. Mordy, Brittany Widner, Karen L. Casciotti, Bess B. Ward
OEAS Faculty Publications
The Eastern Tropical South Pacific is one of the three major oxygen deficient zones (ODZs) in the global ocean and is responsible for approximately one third of marine water column nitrogen loss. It is the best studied of the ODZs and, like the others, features a broad nitrite maximum across the low oxygen layer. How the microbial processes that produce and consume nitrite in anoxic waters interact to sustain this feature is unknown. Here we used 15N-tracer experiments to disentangle five of the biologically mediated processes that control the nitrite pool, including a high-resolution profile of nitrogen loss rates ...
Assessing The Potential To Decrease The Gulf Of Mexico Hypoxic Zone With Midwest Us Perennial Cellulosic Feedstock Production, Andy Vanloocke, Tracy E. Twine, Christopher J. Kucharik, Carl J. Bernacchi
The goal of this research was to determine the changes in streamflow, dissolved inorganic nitrogen (DIN) leaching and export to the Gulf of Mexico associated with a range of large-scale dedicated perennial cellulosic bioenergy production scenarios within in the Mississippi–Atchafalaya River Basin (MARB). To achieve this goal, we used Agro-IBIS, a vegetation model capable of simulating the biogeochemistry of row crops, miscanthus and switchgrass, coupled with THMB, a hydrology model capable of simulating streamflow and DIN export. Simulations were conducted at varying fertilizer application rates (0–200 kg N ha -1) and fractional replacement (5–25%) of current row ...
Candidate Perennial Bioenergy Grasses Have A Higher Albedo Than Annual Row Crops, 2017 University of Illinois at Urbana-Champaign
Candidate Perennial Bioenergy Grasses Have A Higher Albedo Than Annual Row Crops, Jesse N. Miller, Andy Vanloocke, Nuria Gomez-Casanovas, Carl J. Bernacchi
The production of perennial cellulosic feedstocks for bioenergy presents the potential to diversify regional economies and the national energy supply, while also serving as climate ‘regulators’ due to a number of biogeochemical and biogeophysical differences relative to row crops. Numerous observational and model-based approaches have investigated biogeochemical trade-offs, such as increased carbon sequestration and increased water use, associated with growing cellulosic feedstocks. A less understood aspect is the biogeophysical changes associated with the difference in albedo (a), which could alter the local energy balance and cause local to regional cooling several times larger than that associated with offsetting carbon. Here ...
Analysis Of Microbial Diversity In Disturbed Soil, 2017 University of Akron
Analysis Of Microbial Diversity In Disturbed Soil, Tyler G. Sanda
Honors Research Projects
This paper uses the composition and abundance of microbial species to analyze soil recovery in disturbed land. Surface mining disturbs ecological communities throughout the world. As organizations seek to reclaim these disturbed lands, a proper analysis of recovery is needed. In previous studies, recovery of disturbed land was limited to surface examinations, which do not characterize the possible unseen devastating effects of the subsoil. Soil microorganisms are extremely sensitive to environmental changes such as strip mining. It is proposed that these microorganisms may serve as better indicators of recovery post disturbance. Our analysis indicates microbial recovery, however it may not ...
An Investigation Of Paleo-Wildfires During The Cretaceous-Paleogene (K-Pg) Boundary At El Kef, Tunisia, 2017 University of Colorado, Boulder
An Investigation Of Paleo-Wildfires During The Cretaceous-Paleogene (K-Pg) Boundary At El Kef, Tunisia, Michael Gross
Undergraduate Honors Theses
The causes and consequences of the Cretaceous-Paleogene mass extinction have long been a source of contention. Several models predict that enough thermal radiation from the bolide impact was produced to ignite wildfires at least regionally and possibly on a global scale, raising average temperatures by up to ~10°C, and releasing large amounts of CO2 and CO. However, the role of regional versus global wildfire events as an environmental stressor, as well as the sources of the fire (land vegetation vs. hydrocarbon reservoirs) and its expression in terrestrial and marine archives, remains controversial. Typically, wildfires are preserved in the ...
The Impacts Of Soil Properties On Mixed Conifer Seedling Recruitment In The Post-Fire Environment Of Eastern Oregon, 2017 University of Colorado, Boulder
The Impacts Of Soil Properties On Mixed Conifer Seedling Recruitment In The Post-Fire Environment Of Eastern Oregon, Leah Bollin
Undergraduate Honors Theses
Climate change is increasing the frequency and severity of fires, especially in the Western United States, making it pertinent that tree regeneration rates and causes are understood. The goal of this research is to assess the impacts of post-fire environments on seedling regeneration in dry conifer forest of eastern Oregon’s Blue Mountain Ecoregion. Specifically, I seek to determine whether soil properties determine successful seedling recruitment. In the summer of 2016, sixty-eight soil samples from across four different fires in the Blue Mountain Ecoregion were collected to analyze for total carbon, total nitrogen, and pH. The soil variables were compared ...
Effects Of Silvopasture Establishment On Aqueous And Gaseous Soil N Losses At The University Of New Hampshire Organic Dairy Research Farm, 2017 University of New Hampshire, Durham
Effects Of Silvopasture Establishment On Aqueous And Gaseous Soil N Losses At The University Of New Hampshire Organic Dairy Research Farm, Kathryn Ann Slebodnik
Honors Theses and Capstones
The expansion of local agriculture in the New England region is putting increased pressure on farmers to expand their arable land base. While clear-cutting is a traditional method of converting forested land to agriculture, it is known for having adverse ecological impacts. To minimize these impacts, farmers can create a silvopasture which incorporates a portion of the original forest canopy into pastures or crop fields. This study evaluates the impact of land-use changes for agriculture on soil nitrogen (N) retention. In particular, this study investigates the differences in soil N turnover, gaseous loss, and aqueous loss among an established forest ...
Using High-Resolution Glider Data And Biogeochemical Modeling To Investigate Phytoplankton Variability In The Ross Sea, 2017 College of William and Mary - Virginia Institute of Marine Science
Using High-Resolution Glider Data And Biogeochemical Modeling To Investigate Phytoplankton Variability In The Ross Sea, Daniel Edward Kaufman
Dissertations, Theses, and Masters Projects
As Earth’s climate changes, polar environments experience a disproportionate share of extreme shifts. Because the Ross Sea shelf has the highest annual productivity of any Antarctic continental shelf, this region is of particular interest when striving to characterize current and future changes in Antarctic systems. However, understanding of mesoscale variability of biogeochemical patterns in the Ross Sea and how this variability affects assemblage dynamics is incomplete. Furthermore, it is unknown how the Ross Sea may respond to projected warming, reduced summer sea ice concentrations, and shallower mixed layers during the next century. To investigate these dynamics and explore their ...
Calcium Carbonate Prenucleation Clusters: Towards Unification Of Classical And Non-Classical Nucleation Theory, 2017 Southern Cross University
Calcium Carbonate Prenucleation Clusters: Towards Unification Of Classical And Non-Classical Nucleation Theory, Jonathan Avaro
The aim of this PhD was to develop analytical methods to characterize the physical and chemical characteristics of calcium carbonate prenucleation clusters and their role in the mineral nucleation process. A novel sample environment was developed to allow fast in situ and ex situ kinetic experiments when coupled to synchrotron and neutron radiation techniques. The results obtained through these experiments support findings from previous computer simulations and define the impact of pH and saturation state on the very early stages of calcium carbonate mineral formation via non-classical nucleation processes.
Terrestrial Versus Aquatic Carbon Fluxes In An Agricultural Coastal Floodplain, 2017 Southern Cross University
Terrestrial Versus Aquatic Carbon Fluxes In An Agricultural Coastal Floodplain, Jackie Roslyn Webb
In ecosystems at the terrestrial-aquatic interface, the carbon cycle is intricately connected between these two components. However, these terrestrial-aquatic carbon subsidies are often neglected in carbon budgets. This dissertation addresses the role of the aquatic pathway in the carbon budget of a “model” ecosystem representing a well constrained catchment. By combining terrestrial and aquatic methodologies, the study revealed important findings on the drivers of aquatic carbon fluxes and the relative contribution of this pathway to offsetting the land carbon sink. This study demonstrated that an interdisciplinary approach to terrestrial-aquatic ecosystems propels our understanding of carbon cycling in these systems.
The Influence Of Submarine Groundwater Discharge On Carbon, Nutrient And Greenhouse Gases Dynamics In Coastal Waters, 2017 Southern Cross University
The Influence Of Submarine Groundwater Discharge On Carbon, Nutrient And Greenhouse Gases Dynamics In Coastal Waters, Mahmood Sadat-Noori
This thesis documents the use of mass balance modelling combined with a multi-tracer approach, to quantify, interpret and manage coastal groundwater discharge. The dynamic characteristics of groundwater discharge requires intensive and multifaceted sampling strategies to constrain its effects on surface water quality. This thesis highlights that dissolved carbon, greenhouse gases and nutrient export from estuaries are strongly coupled to groundwater discharge therefore, should not be neglected in coastal carbon and nutrient budget studies. Results presented here indicate that even small volumetric groundwater discharge fluxes occurring on large scales play a major role in the hydrology and biogeochemistry of coastal ecosystems.
Nitrate Loading In The Saw Kill Watershed: Small Watershed Nutrient Dynamics, Answering A Community Question, And Assessing Methodological Approaches, Marco Sebastian Spodek
Senior Projects Spring 2017
Biogeochemical cycles mitigate the movement of nutrients through ecosystems at a variety of scales. Within aquatic systems, nitrogen (N) and phosphorus (P) are especially critical due to their high influence on primary production and decomposition. However, in excess, N and P can pose hazardous ecological effects downstream. Excessive loading of both N and P to waterways can facilitate harmful algal blooms or dead zones in reservoirs and at drainage points. Extensive research over the past half century has shown that the majority of nutrient loading to aquatic systems is the result of anthropogenic land use. While the effects of these ...
A Multi-Faceted Biogeochemical Approach To Analyzing Hypoxia In Green Bay, Lake Michigan, 2016 University of Wisconsin-Milwaukee
A Multi-Faceted Biogeochemical Approach To Analyzing Hypoxia In Green Bay, Lake Michigan, Shelby Labuhn
Theses and Dissertations
Green Bay, Lake Michigan is a large freshwater estuary that has experienced seasonal hypoxia for decades. Hypoxia, or dissolved oxygen concentrations less than 2 mg L-1, is a problem in coastal ecosystems around the world because it has a negative impact on ecosystem health by decreasing biodiversity and fisheries. In order to create adequate management policies for hypoxia, it is important to understand the sources and sinks of oxygen within Green Bay. This study utilizes a number of traditional and novel field methods to measure the production and respiration of oxygen within lower Green Bay, defined as south of Chambers ...