University of San Francisco
Bates College
Montana Tech of the University of Montana
Pomona College
Boise State University
Western University
Clemson University
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 ...
Catalyzed Synthesis Of Zinc Clays By Prebiotic Central Metabolites,
2017
University of Kentucky
Catalyzed Synthesis Of Zinc Clays By Prebiotic Central Metabolites, Ruixin Zhou, Kaustuv Basu, Hyman Hartman, Christopher J. Matocha, S. Kelly Sears, Hajatollah Vali, Marcelo I. Guzman
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
Virginia Institute of Marine Science
A Model Archive For A Coupled Hydrodynamic-Sediment Transport-Biogeochemistry Model For The Rhône River Sub-Aqueous Delta, France, Julia M. Moriarty, Courtney K. Harris, Katja Fennel, Kehui Xu, Christophe Rabouille, Marjorie A.M. Friedrichs
Data
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 ...
Assessing The Potential To Decrease The Gulf Of Mexico Hypoxic Zone With Midwest Us Perennial Cellulosic Feedstock Production,
2017
Iowa State University
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
Andy VanLoocke
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
Andy VanLoocke
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 ...
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 ...
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 ...
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 ...
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
Theses
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
Theses
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.
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 ...
Declining Dissolved Oxygen In The Central California Current Region,
2016
University of Maine
Declining Dissolved Oxygen In The Central California Current Region, Alice Ren
Electronic Theses and Dissertations
A potential consequence of climate change is a global decrease in dissolved oxygen at depth due to changes in the balance of ventilation, mixing, respiration, and photosynthesis in the oceans. Regionally, the California Current has experienced dissolved oxygen declines since the late 1980s with observations from Oregon and the Southern California Bight. Here, we present observations of declining dissolved oxygen along CalCOFI Line 67 off of Monterey Bay, in the Central California Current region, and investigate likely mechanisms. The hydrographic cruises obtained dissolved oxygen measurements 50-300 km from shore between 1998 and 2013, with quasi-seasonal sampling resolution. Dissolved oxygen decreased ...
Examining Denitrification In Agricultural Ditch Sediments Vegetated With Rice Cutgrass (Leersia Oryzoides): Modeling Seasonal Variation Across Increasing Levels Of Nitrate Loading And Model Application To Pre-Existing Datasets,
2016
University of Arkansas, Fayetteville
Examining Denitrification In Agricultural Ditch Sediments Vegetated With Rice Cutgrass (Leersia Oryzoides): Modeling Seasonal Variation Across Increasing Levels Of Nitrate Loading And Model Application To Pre-Existing Datasets, Shannon Lee Speir
Theses and Dissertations
Nitrogen (N) derived from fertilizer application in agricultural systems may contribute to significant environmental impacts, including eutrophication of fresh and coastal waters. Rice cutgrass (Leersia oryzoides) can significantly enhance denitrification potential in agricultural ditch sediments, but relationships with known drivers are not well understood. To address this, I examined effects of nitrate (NO3-) availability on dinitrogen gas (N2) and NO3- fluxes seasonally in Chapter 2. Denitrification rates were measured as N2 flux from intact vegetated sediment cores using Membrane Inlet Mass Spectrometry (MIMS). Michaelis-Menten models were developed from observations to mathematically describe N2 fluxes across the spring, summer, and fall ...
Physiology, Fe(Ii) Oxidation, And Fe Mineral Formation By A Marine Planktonic Cyanobacterium Grown Under Ferruginous Conditions,
2016
Iowa State University
Physiology, Fe(Ii) Oxidation, And Fe Mineral Formation By A Marine Planktonic Cyanobacterium Grown Under Ferruginous Conditions, Elizabeth D. Swanner, Wenfang Wu, Likai Hao, Marina Lisa Wüstner, Martin Obst, Dawn M. Moran, Matthew R. Mcilvin, Mak A. Saito, Andreas Kappler
Elizabeth D. Swanner
Evidence for Fe(II) oxidation and deposition of Fe(III)-bearing minerals from anoxic or redox-stratified Precambrian oceans has received support from decades of sedimentological and geochemical investigation of Banded Iron Formations (BIF). While the exact mechanisms of Fe(II) oxidation remains equivocal, reaction with O2 in the marine water column, produced by cyanobacteria or early oxygenic phototrophs, was likely. In order to understand the role of cyanobacteria in the deposition of Fe(III) minerals to BIF, we must first know how planktonic marine cyanobacteria respond to ferruginous (anoxic and Fe(II)-rich) waters in terms of growth, Fe uptake ...
Laboratory Simulation Of An Iron(Ii)-Rich Precambrian Marine Upwelling System To Explore The Growth Of Photosynthetic Bacteria,
2016
Iowa State University
Laboratory Simulation Of An Iron(Ii)-Rich Precambrian Marine Upwelling System To Explore The Growth Of Photosynthetic Bacteria, Markus Maisch, Wenfang Wu, Andreas Wu, Elizabeth D. Swanner
Elizabeth D. Swanner
A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling from hydrothermal sources in the Precambrian ocean was oxidized by molecular oxygen [O2] produced by cyanobacteria. The oldest BIFs, deposited prior to the Great Oxidation Event (GOE) at about 2.4 billion years (Gy) ago, could have formed by direct oxidation of Fe(II) by anoxygenic photoferrotrophs under anoxic conditions. As a method for testing the geochemical and mineralogical patterns that develop under different biological scenarios, we designed a 40 cm long vertical flow-through column to simulate ...
Convergence In Nitrogen Deposition And Cryptic Isotopic Variation Across Urban And Agricultural Valleys In Northern Utah,
2016
Iowa State University
Convergence In Nitrogen Deposition And Cryptic Isotopic Variation Across Urban And Agricultural Valleys In Northern Utah, Steven J. Hall, E. M. Ogata, S. R. Weintraub, M. A. Baker, J. R. Ehleringer, C. I. Czimczik, D. R. Bowling
Ecology, Evolution and Organismal Biology Publications
The extent to which atmospheric nitrogen (N) deposition reflects land use differences and biogenic versus fossil fuel reactive N sources remains unclear yet represents a critical uncertainty in ecosystem N budgets. We compared N concentrations and isotopes in precipitation-event bulk (wet + dry) deposition across nearby valleys in northern Utah with contrasting land use (highly urban versus intensive agriculture/low-density urban). We predicted greater nitrate (NO3−) versus ammonium (NH4+) and higher δ15N of NO3− and NH4+ in urban valley sites. Contrary to expectations, annual N deposition (3.5–5.1 kg N ha−1 yr−1) and inorganic N concentrations were ...
Using Rare Earth Elements To Constrain Particulate Organic Carbon Flux In The East China Sea,
2016
Old Dominion University
Using Rare Earth Elements To Constrain Particulate Organic Carbon Flux In The East China Sea, Chin-Chang Hung, Ya-Feng Chen, Shih-Chieh Hsu, Kui Wang, Jianfang Chen, David J. Burdige
OEAS Faculty Publications
Fluxes of particulate organic carbon (POC) in the East China Sea (ECS) have been reported to decrease from the inner continental shelf towards the outer continental shelf. Recent research has shown that POC fluxes in the ECS may be overestimated due to active sediment resuspension. To better characterize the effect of sediment resuspension on particle fluxes in the ECS, rare earth elements (REEs) and organic carbon (OC) were used in separate two-member mixing models to evaluate trap-collected POC fluxes. The ratio of resuspended particles from sediments to total trap-collected particles in the ECS ranged from 82-94% using the OC mixing ...
High-Resolution Signatures Of Oxygenation And Microbiological Activity In Speleothem Fluid Inclusions,
2016
New Mexico Institute of Mining and Technology
High-Resolution Signatures Of Oxygenation And Microbiological Activity In Speleothem Fluid Inclusions, Nigel Blamey, Penelope J. Boston, Laura Rosales-Lagarde
International Journal of Speleology
Speleothems frequently host “fossil” fluids that were trapped in small inclusions during growth. Such fluids may provide valuable clues to past microbial, geochemical, and climatic processes during their formation. However, one difficulty is to understand which gases represent background atmosphere and fluids within a given cave system at a particular time, and which may be the product of post-trapping residual microbial activity or abiotic chemical reactions? Do we have any hope of sorting out these differences? The success depends on a quantitative understanding of the gas composition trapped in the inclusions and an understanding of the interactions of cave mineralogy ...
