Biogeochemistry Commons^™

Phosphorus Variability In The Area Of Influence Of The Mid-Barataria Sediment Diversion, Peter Mates

LSU Master's Theses

Man-made levees along the lower Mississippi River prevent delivery of sediment from building and maintaining Louisiana’s coastal wetlands. The Mid-Barataria sediment diversions is designed to reintroduce Mississippi River water, sediment, and nutrients into the sediment-starved Barataria Basin. Phosphorus (P) is an important macronutrient for regulating primary production in coastal marine ecosystems. Wetlands can serve as a sink or source for phosphorus to the overlying water column through various retention and release processes, dependent on concentration. Louisiana coastal systems can be phosphorus limited due to much higher concentrations of bioavailable Nitrogen in river water. The high soluble molar N:P ( >50:1) …

Mechanisms Of Carbon Movement And Stabilization In Mangrove Wetlands, Carey Schafer

USF Tampa Graduate Theses and Dissertations

Mangrove forests have higher rates of carbon storage per unit area than any other coastal or terrestrial habitat, largely due to their significant soil stocks. More effort has been placed on quantifying mangrove soil carbon stock, the amount of carbon stored in the upper meter of mangrove soils, than identifying the processes governing in situ soil organic carbon (SOC) cycling and stabilization. An understanding of the mechanisms related to carbon transport and stability is necessary to constrain current wetland carbon stocks and to determine how sea level rise will impact future carbon stores. This study uses a variety of radiometric …

Assessment Of Soil Protein And Refractory Soil Organic Matter Across Two Chronosequences Of Newly Developing Marshes In Coastal Louisiana, Usa, Stuart Alexander Mcclellan

LSU Doctoral Dissertations

The impacts of sea-level rise and hydrologic manipulation are threatening the stability of coastal marshes throughout the world, thereby increasing the potential for re-mineralization of soil organic matter (SOM) in these systems. Such threats have prompted marsh restoration efforts, particularly in coastal Louisiana, yet it is unclear how the slowly decomposing (refractory) and quickly decomposing (labile) fractions of SOM may be differentially affected by different approaches to marsh restoration. Additionally, otherwise labile compounds may accumulate in the soil via a range of protective mechanisms, including rapid burial and association with organic compounds that are thought to enhance soil aggregation, such …

Microdialysis: A Method For Quantifying In Situ Nitrogen Fluxes In Soil Microsites, Srusti Maddala, Mary C. Savin, Julie A. Stenken, Lisa S. Wood

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Microdialysis, a diffusion-based sampling technique commonly used in biomedical research, has recently been recognized as a candidate for monitoring chemical changes in the rhizosphere. The information it provides about nutrient diffusion may improve nitrogen use efficiency, leading to enhanced management and success of restoration projects. The objective of this study was to determine the efficacy of microdialysis sampling to quantify the relative recoveries (RR%) of nitrate-N and ammonium-N, the two inorganic nitrogen compounds typically found in soil. The effects of microdialysis flow rate, sample medium concentration, and the presence of both analytes in solution on the relative recoveries obtained from …

Dissolved Organic Matter Movement Across Lake Superior’S Terrestrial-Stream-Coastal Interface, Karl M. Meingast

Dissertations, Master's Theses and Master's Reports

Dissolved organic matter (DOM) represents a carbon pool that can be easily translocated between ecosystems with the movement of water. This study examines the controls on DOM quantity and character delivered to Lake Superior primarily during the snowmelt period. We employed long-term stream dissolved organic carbon (DOC) data to determine quantity as well as absorption and fluorescence spectroscopy to analyze DOM structure. Our results indicate that an increasing trend in DOC concentrations, likely driven by decreases in acidity of precipitation, combined with slightly less annual runoff have resulted in relatively constant fluxes of DOM to Lake Superior. Additionally, our study …

Assessing Diagenetic Conditions In The Late Triassic Chinle Formation Through Petrographic And Geochemical Analysis Of Phytosaur Teeth, John Fortner

Earth Sciences Theses and Dissertations

The Upper Triassic (Norian; ~227-208 Ma) Chinle Formation of Petrified Forest (PeFo) National Park was deposited during a time of major tectonic breakup and profound changes in atmospheric circulation and faunal compositions. Little has been done however to assess whether surficial paleoenvironmental trends related to deterioration of the Late Triassic Megamonsoon resulted in similar trends in the early diagenetic environment. Here, we use phytosaur tooth dentin as a proxy for diagenetic conditions in the Chinle of PEFO, as its greater susceptibility to chemical alteration relative to enamel makes it an excellent substrate from which changing diagenetic conditions may be studied …

The Potential Acidification Of The Mulberry River, Arkansas, Jason Richard Burgess-Conforti

Graduate Theses and Dissertations

The Mulberry River is a 110 km long tributary of the Arkansas River in northwest Arkansas and has been designated as a National Wild and Scenic River since 1992. In 2008, the Mulberry River was added to the 303(d) list of impaired water bodies due to the low pH of a 14.6 km segment of the river which has since increased to 68.7 km. To date, there has been little research performed on the Mulberry River and long-term routinely sampled water quality data is unavailable. The objectives of this dissertation were 1) to evaluate changes in water quality of the …

Losses Of Mineral Soil Carbon Largely Offset Biomass Accumulation Fifteen Years After Whole-Tree Harvest In A Northern Hardwood Forest, Matthew A. Vadeboncoeur, Steven P. Hamburg, Chris E. Johnson, Jonathan Sanderman

All Materials

Changes in soil carbon stocks following forest harvest can be an important component of ecosystem and landscape-scale C budgets in systems managed for bioenergy or carbon-trading markets. However, these changes are characterized less often and with less certainty than easier-to-measure aboveground stocks. We sampled soils prior to the whole-tree harvest of Watershed 5 at the Hubbard Brook Experimental Forest in 1983, and again in years 3, 8, and 15 following harvest. The repeated measures of total soil C in this stand show no net change in the O horizon over 15 years, though mixing with the mineral soil reduced observed …

Evaluating Seasonal Nutrient Fluxes In Emerging And Eroding Wetlands Of The Louisiana Delta Plain, Kiran Upreti

LSU Doctoral Dissertations

Deltaic wetlands can ameliorate high NO₃^- loads via denitrification, a dominant NO₃^- reduction pathway in inland and coastal habitats. Dissimilatory Nitrate Reduction to Ammonia (DNRA), in contrast to denitrification, conserves N within the system and has been found to be favored over denitrification with increase in salinity and temperature. There are no studies in the Louisiana Deltaic plain with simultaneous estimation of denitrification and DNRA. Increased P availability has been shown to increase denitrification so it is essential to understand P biogeochemistry when studying N cycle. Here, we evaluated net denitrification using N₂:Ar and …

Biogeochemical Response To Vegetation And Hydrologic Change In An Alaskan Boreal Fen Ecosystem, Danielle L. Rupp

Dissertations, Master's Theses and Master's Reports

Boreal peatlands store approximately one third of the earth’s terrestrial carbon, locked away in currently waterlogged and frozen conditions. Peatlands of boreal and arctic ecosystems are affected increasingly by shifting hydrology caused by climate change. The consequences of these relatively rapid ecosystem changes on carbon cycling between the landscape and the atmosphere could provide an amplifying feedback to climate warming. Alternatively, the advancement of terrestrial vegetation into once waterlogged soils could uptake carbon as a sink. Previous work suggests that fens will become an increasingly dominant landscape feature in the boreal. However, studies investigating fens, their response to hydrologic and …

Seasonal Soil Carbon Fluxes In Transitioning Agricultural Soils In Central Washington State: Relations To Land-Use, Environmental Factors And Soil Carbon-Nitrogen Characteristics, Brandon Kautzman

All Master's Theses

Changing agricultural land-use practices to increase soil carbon sequestration contributes to climate change mitigation and improved food security by moving CO₂ from the atmosphere into soil as soil organic carbon (SOC). In 2016, a farm in Thorp, Washington, Spoon Full Farm, began converting land historically farmed using conventional methods of tillage and synthetic fertilizers to conservation farming methods with direct seeding and organic soil amendments with a goal of sequestering carbon in the soil. This project evaluates relationships of soil CO₂ respiration and net ecological exchange (NEE) with land-use types, seasonal environmental factors (air temperature, relative humidity, soil …

Investigation Of Biogeochemical Mechanisms Of Greenhouse Gas Production In The Urban Hudson River Estuary, Brian Alan Brigham

Dissertations, Theses, and Capstone Projects

Coastal megacities deposit significant amounts of carbon (C), nitrogen (N) and other pollutants into surrounding waters. These inputs, including wastewater and surface water runoff, may affect estuarine and adjacent wetland biogeochemical cycles, microbial production and ultimately greenhouse gas (GHG) efflux. In many megacities pollutant loading is typically greatest after periods of precipitation when the volume of wastewater and storm water runoff exceeds local sanitation capacity, resulting in the discharge of raw sewage into adjacent waters. These combined sewage overflow (CSO) events have received considerable attention primarily due to their potential impact on human health and eutrophication. However, whether these events …

Radical Social Ecology As Deep Pragmatism: A Call To The Abolition Of Systemic Dissonance And The Minimization Of Entropic Chaos, Arielle Brender

Student Theses 2015-Present

This paper aims to shed light on the dissonance caused by the superimposition of Dominant Human Systems on Natural Systems. I highlight the synthetic nature of Dominant Human Systems as egoic and linguistic phenomenon manufactured by a mere portion of the human population, which renders them inherently oppressive unto peoples and landscapes whose wisdom were barred from the design process. In pursuing a radical pragmatic approach to mending the simultaneous oppression and destruction of the human being and the earth, I highlight the necessity of minimizing entropic chaos caused by excess energy expenditure, an essential feature of systems that aim …

Effects Of Increasing Deciduous Shrub Litter On Ecosystem Functioning In Alpine Tundra, Alejandro Emmanuel Benhumea

Open Access Theses & Dissertations

Rising temperatures due to global warming have resulted in rapid environmental changes in northern environments, resulting in an increase in deciduous shrub growth which has the potential to alter soil ecosystem properties and processes. In order to address some potential mechanisms by which shrubs alter ecosystem properties and processes, we designed an experiment which separated the effects of physical shrub presence and the effects of litter quantity in a fully factorial experiment on a north facing alpine plateau in the southwest Yukon, Canada. Specifically, we asked the following questions: What are effects of shrub litter, independent of shrub presence, on …

Mapping Soil Organic Carbon (Soc) In A Semi-Arid Mountainous Watershed Using Variables From Hyperspectral, Lidar And Traditional Datasets, Ryan Matthew Will

Boise State University Theses and Dissertations

Quantifying soil organic carbon (SOC) in complex terrain is challenging due to its high spatial variability. Generally, limited discrete observations of SOC data are used to develop spatially distributed maps of SOC by developing quantitative relationships between SOC and available spatially distributed variables. In many ecosystems, remotely sensed information on aboveground vegetation can be used to predict belowground carbon stocks. In this research, we developed maps of SOC across a semi-arid watershed based on discrete field observations and modeling using a suite of variables inclusive of hyperspectral and lidar datasets; these observations provide insights into the controls on soil carbon …

Assessing The Periodic Groundwater Flow Conditions Of A Perched Aquifer System In The Daniel Boone National Forest, Ethan Sweet

Posters-at-the-Capitol

Assessing the Periodic Groundwater Flow Conditions of a Perched Aquifer System in the Daniel Boone National Forest

Ethan Sweet and Jonathan Malzone

Eastern Kentucky University, Department of Geosciences

Natural ephemeral wetlands situated among the ridge-tops in the Daniel Boone National Forest serve as reservoirs that recharge a shallow groundwater system. Unique interactions between surface and groundwater in these isolated systems provide substantial support for the native ecosystem, serving as a breeding ground for amphibians and as source water for vegetation—especially in periods of drought. Currently it is not understood how groundwater could provide regional biodiversity, a drought buffer, or a …

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 …

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, …

Analysis Of Microbial Diversity In Disturbed Soil, Tyler G. Sanda

Williams Honors College, 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 …

Rock Magnetic Investigation Of The Michigan Basin Soils And Sediments Overlying The Oil-Bearing Silurian Pinnacle Reefs, Jake Tresnak

Dissertations, Master's Theses and Master's Reports

A relationship between the hydrocarbon migration and magnetic properties of near-surface sediments was investigated from several hundreds of samples collected over the hydrocarbon-bearing Silurian pinnacle reef belt of the Michigan Basin. The collected samples were investigated using several rock magnetic methods and optical microscopy. The investigation has not revealed a straightforward relationship between the magnetic susceptibility and hydrocarbon reservoirs within the reef belt; both anomalously high and low susceptibility values were observed. The elevated values are associated with newly formed magnetite in the form of spheroidal grains produced by hydrocarbon-related diagenesis while the extremely low susceptibilities may reflect dissolution of …

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

Graduate 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 …

Silica Uptake And Release In Live And Decaying Biomass In A Northern Hardwood Forest, Wim Clymans, Daniel J. Conley, John J. Battles, Patrick J. Frings, Mary Margaret Koppers, Gene E. Likens, Chris E. Johnson

Civil and Environmental Engineering - All Scholarship

In terrestrial ecosystems, a large portion (20–80%) of the dissolved Si (DSi) in soil solution has passed through vegetation. While the importance of this “terrestrial Si filter” is generally accepted, few data exist on the pools and fluxes of Si in forest vegetation and the rate of release of Si from decomposing plant tissues. We quantified the pools and fluxes of Si through vegetation and coarse woody debris (CWD) in a northern hardwood forest ecosystem (Watershed 6, W6) at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire, USA. Previous work suggested that the decomposition of CWD may have significantly …

Quantifying Peat Carbon Accumulation In Alaska Using A Process-Based Biogeochemistry Model, Sirui Wang, Qianlai Zhuang, Zicheng Yu, Scott Bridgham, Jason K. Keller

Education Faculty Articles and Research

This study uses an integrated modeling framework that couples the dynamics of hydrology, soil thermal regime, and ecosystem carbon and nitrogen to quantify the long-term peat carbon accumulation in Alaska during the Holocene. Modeled hydrology, soil thermal regime, carbon pools and fluxes, and methane emissions are evaluated using observation data at several peatland sites in Minnesota, Alaska, and Canada. The model is then applied for a 10,000 year (15 ka to 5 ka; 1 ka = 1000 cal years before present) simulation at four peatland sites. We find that model simulations match the observed carbon accumulation rates at fen sites …

Cone In Cone Concretions Of The Stanley Group In Southeastern Oklahoma, Kyle B. Ayres

Electronic Theses and Dissertations

Cone in cone concretions found in the Stanley Group of Southeastern Oklahoma have a variety of external and internal attributes which allow diagenetic and theoretical models of formation to be hypothesized. Stanley Group carbonate cone in cone concretions are initially formed in sulfur reducing horizons at shallow burial depths in a poorly circulated possibly deep trough containing siliceous sediments and organic matter. Collected concretions near the town of Smithville, Oklahoma displayed four different external morphologies and four variations of mineral constituents. All concretions contained microscopic cones which initiated diffusion and/or fluid patterns and is an early cementation process that directly …

Compost Land Management And Soil Carbon Sequestration, Kylene A. Hohman

Senior Honors Projects, 2010-2019

Extensive fossil fuel burning has released carbon dioxide into the atmosphere. Under proper ecological conditions plants convert atmospheric carbon dioxide into stable soil organic matter, a natural and efficient means of mitigating climate change. In the symbiotic relationship between mycorrhizae and plants, mycorrhizae provide plants with essential nutrients in exchange for carbon sugars leaked from the plants. Mycorrhizae convert carbon sugars to an exudate called glomalin, a protein that assists in developing soil aggregates composed of sand, silt, and clay. These aggregates, called humus, store carbon for hundreds of years under healthy ecological conditions. Compost prompts soil microbes to aerobically …

Gone With The Wind: Soil Moisture Effects On Gaseous Nitrogen Removal From Wastewater, Faith L. Anderson

Senior Honors Projects

Onsite wastewater treatment systems (OWTS), or septic systems, release nitrogen (N), which can be detrimental to aquatic ecosystems. The final step in the treatment of wastewater is dispersal onto a drainfield, where it percolates through the soil. Part of the N is removed from wastewater and released into the atmosphere as N₂ and N₂O by denitrification, which requires anoxic conditions. Previous studies looking at the effect of soil water-filled pore space (WFPS) on denitrification using clean water with a high level of dissolved O₂ (DO) have identified a minimum of 60% WFPS for denitrification to take …

Effects Of Epichloë Coenophiala−Tall Fescue Symbiosis On Plant-Microbe-Soil Interactions In A Temperate Pasture, Lindsey C. Slaughter

Theses and Dissertations--Plant and Soil Sciences

Plants interact in myriad ways with microorganisms to influence ecosystem processes such as nutrient cycling, which can regulate ecosystem response to global change. One important plant-microbe symbiosis occurs between cool-season grasses and asexual fungal Epichloë endophytes, such as tall fescue (Schedonorus arundinaceus) and Epichloë coenophiala. Because the common toxic strain of the endophyte (CTE) harms grazing livestock, non-livestock toxic endophyte (NTE) strains have been developed and are increasingly deployed in pastures. Little is known about how these symbioses impact other plant-microbe interactions and microbe-mediated soil processes in grassland ecosystems. I conducted three studies to determine how E. …

The Role Of Amino Acids In The Nitrogen Cycle Of Peatlands, Tia Scarpelli

Dissertations, Master's Theses and Master's Reports

Future release of carbon from peatlands in response to climate change may be impacted by nitrogen limitation. The current study considers the role of amino acids as a nitrogen source in peatlands. The total free amino acid (TFAA) concentration for peats ranged from 0-2.3 µM, and leucine was the primary contributor. The dominance of sedge or ericaceous shrub plant types did not significantly impact the TFAA pool. Ammonium concentrations were much greater than TFAA and nitrate concentrations. TFAA concentrations were greatest in spring and least in fall. The springtime maxima and summer decrease in concentrations were simulated in a modeling …

Evaluating The Biogeochemical Functioning Of A Constructed Fen On The Post-Mining Landscape Of Athabasca Oil Sands Region, Fort Mcmurray, Alberta, Canada, Felix C. Nwaishi

Theses and Dissertations (Comprehensive)

Peatlands have a unique biogeochemical function, characterized by an imbalance between the rates of biomass accumulation and decomposition. These characteristics facilitate the ability of peatlands to support the sequestration of nutrients and carbon. In disturbed peatlands, these functions are compromised. Thus, reclamation targets amongst other key functions, the recovery of biogeochemical functioning. These functions could serve as a measure of recovery to conditions that are present in natural analogues. This thesis examines the recovery of microbially-mediated nutrient transformation processes in a fen peatland that was constructed on a post-mining landscape in the Athabasca oil sands region, Fort McMurray, Alberta. The …

Mercury In Coniferous And Deciduous Upland Forests In Northern New England, Usa: Implications Of Climate Change, J. B. Richardson, A. J. Friedland

Dartmouth Scholarship

Climatic changes in the northeastern US are expected to cause coniferous stands to transition to deciduous stands over the next hundred years. Mercury (Hg) sequestration in forest soils may change as a result. In order to understand potential effects of such a transition, we studied aboveground vegetation and soils at paired coniferous and deciduous stands on eight mountains in Vermont and New Hampshire, USA.