Biogeochemistry Commons^™

What Limits Dryland Ecosystems? Patterns Of Soil Fertility And Resource Limitation In The Chihuahuan Desert, Dylan Stover

Open Access Theses & Dissertations

Human activities are substantially altering global resource cycles with widespread implications for biogeochemistry and ecosystem functioning globally. Drylands, regions where precipitation is outweighed by water losses, are especially sensitive to these large shifts in resource cycles due to their inherently low and variable resource availability. In these regions, resource availability and biological activity are often concentrated around plants – or fertile islands – and predominantly driven by pulses of water. However, our knowledge of the processes influencing biological productivity in drylands – patterns of soil fertility and resource limitation – remains lacking, and their unique biogeochemical and biological processes create …

A Bioarchaeological Study Of The Individuals From The Városfalva Burial Mound In Transylvania, Romania (15th-19th Century), Vanessa C. Reeves

USF Tampa Graduate Theses and Dissertations

This study explores the lives and deaths of the Szekler people recovered from a burial mound in the Transylvanian village of Városfalva. The Transylvanian plateau is located in present day Romania, and is protected on the east and the south by the Carpathian Mountains. The Szekler people arrived in this area around 1000 CE, and were a nomadic group originating in the Asian Steppes region who later intermarried with various migratory groups as they moved across the Eurasian plains. The Szeklers eventually banded together with the proto-Hungarian Magyar peoples and settled in the Carpathian Basin, the easternmost frontier of the …

Spatio-Temporal Characterization Of Trace Metals Across The West Florida Shelf And During The Decline Of The North Atlantic Spring Bloom, Delfina Paola Navarro-Estrada

USF Tampa Graduate Theses and Dissertations

Phytoplankton in the marine environment require the trace metals manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and cadmium (Cd) to catalyze cellular processes driving photosynthesis, including macronutrient (nitrogen, phosphorus, and carbon) acquisition, light harvesting, and protection from oxidative stress. The high biological demand for these elements, coupled with their low concentrations in the ocean, can limit primary production and shape community composition in marine ecosystems, highlighting the need to understand the drivers behind trace metal distributions and their interplay with phytoplankton growth across biogeochemical regimes. This dissertation characterizes the spatial and temporal distributions of dissolved …

Mcl1 And Hexokinase 2 Form A Glucose Metabolic Regulatory Axis, Robert Lee

All ETDs from UAB

Hexokinase 2 (HK2) initiates glucose metabolism by catalyzing the conversion of glucose to glucose-6-phosphate providing the starting substrate for a vast array of metabolic pathways such as glycolysis, pentose phosphate pathway (PPP), amino acid biosynthesis and others. While HK2’s metabolic role in normal physiologic function (such as in cardiomyocytes) and cancers (through driving the Warburg Effect) are well established, there is emerging evidence that supports HK2 is also a critical mediator of protein-protein interactions that regulate cell survival. Through comprehensive review, we explore how HK2 contributes to cell survival through metabolic and protein scaffolding roles. We also investigate a novel …

Effect Of Seasonal Variability In Methane Emissions And Iron Redox Chemistry At Terrestrial-Aquatic Interfaces, Hermes C. Ruiz

Master's Theses

Methane (CH₄) emissions at terrestrial–aquatic interfaces (TAIs) are significant contributors to the global carbon budget, yet the mechanisms driving methanogenesis remain poorly understood. Limited data exist on how seasonal variations and redox processes influence CH₄ fluxes in these dynamic ecosystems. This study addressed two questions: (1) How are CH₄ fluxes in riverine floodplains and adjacent hillslopes impacted by seasonal variations? (2) What roles do metal redox processes (e.g., iron (Fe)) play in regulating methanogenesis?

In-situ CH₄ flux and solid-phase Fe speciation were quantified in East River, CO, under flooded and drained conditions. Groundwater chemistry, gas flux, and soil physical properties …

Compound-Specific Isotope Records Of Dust Provenance And Hydroclimate In The North Pacific And Marginal Seas Of East Asia: Integrating N-Alkane Δ13c And Δd With Standardized Analytical Frameworks, Julian W. Traphagan

LSU Doctoral Dissertations

This dissertation presents advancements in compound-specific isotope analysis (CSIA) through methodological innovation and paleoclimate reconstruction in Central and East Asia. Utilizing plant wax n-alkanes from International Ocean Discovery Program (IODP) and Ocean Drilling Program (ODP) sediment cores, this research reconstructs atmospheric circulation shifts responding to tectonic evolution and climate transitions since the Late Miocene.

Chapter 1 investigates hydrogen isotope compositions (δD_wax) from IODP U1430 (Sea of Japan), ODP 886, and ODP 1208 (North Pacific) to trace dust provenance and hydroclimate changes since ~13 Ma. Results reveal persistently segmented source-to-sink systems: the Sea of Japan dominated by westerly …

Ocean And Coastal Acidification Monitoring Priorities For The Northeast Us And Eastern Canada, Christopher Hunt, Austin Pugh, Jake Kritzer, Samantha Siedlecki, Kumiko Azetsu-Scott, Parker Gassett, Diane Lavoie, Adam Pimenta, Amy Trice, Elizabeth Turner

Faculty Publications

The Interagency Working Group on Ocean Acidification Monitoring Prioritization Plan 2024 calls for Coastal Acidification Networks to identify the ocean and coastal acidification (OCA) monitoring needs most important for their regions. The Northeast Coastal Acidification Network (NECAN) organized a webinar series to study regional needs, which culminated with a workshop in November 2023. This workshop led to the identification of six priority new Monitoring Needs in addition to the maintenance of current monitoring efforts:

• Improve spatial and temporal scale of monitoring co-located OCA variables and biological measurements to better resolve variability of acidification dynamics in concert with biological processes …

Assessing Greenhouse Gas Emissions From Michigan’S Drowned River Mouths Using In Situ And Remote Sensing Methods, Jillian A. Greene

Masters Theses

Freshwater estuaries are natural contributors to the carbon cycle including production and emission of methane (CH4) and carbon dioxide (CO2), potent greenhouse gases (GHGs); however, estimates of their contribution to regional and global GHG emissions is largely unconstrained. Few studies have examined the quantification and drivers of lake CH4 and CO2 production in the Great Lakes region and how it may differ in response to anthropogenic development. In this study, CH4 and CO2 emissions were measured from three drowned river mouth estuaries (DRMs) along the eastern shore of Lake Michigan in 2024. The DRMs exist along a latitudinal gradient ranging …

Comparison Of Nutrient Concentrations And Primary Production Indicators Across Plume Fronts, Taylor Dishon

Electronic Theses and Dissertations

Coastal buoyant plumes carry low-salinity waters containing particulate and dissolved terrestrial materials with an abundance of nutrients into the coastal ocean, including inorganic nitrogen and phosphorous. Plume fronts act as transport barriers created from the convergence of a fresher plume with an older, saltier plume or with ambient waters, leading to potential accumulation of phytoplankton and nutrients. This accumulation creates an optimal environment for primary production. The primary goals of this study were: to investigate the distribution of and potential relationships between nutrient concentrations and chlorophyll a across plume fronts of the Winyah Bay River Plume, and examine potential relationships …

Using Triple Oxygen Isotopes To Investigate Water Usage In Desert Ecosystems, Cloe V. Knutson

Earth and Planetary Sciences ETDs

In arid environments, maintaining water balance can be more critical for survival than obtaining food. As droughts intensify, understanding how animals manage body water is essential. Triple oxygen isotope analysis provides a novel way to trace water sources in animals, distinguishing contributions from free water, food-derived oxygen, and atmospheric O₂. We developed an equilibration method using CO₂–H₂O oxygen exchange and measured δ^’18O and Δ^’17O values via tunable infrared laser direct spectroscopy (TILDAS). Validated against traditional fluorination methods, this technique enables streamlined analysis of whole blood and plant samples. Applied to …

The Astrobiological Figure Of Humboldt As Pioneer In The Rock Varnish Research, Jose Jordan-Soria

Homage to Alexander von Humboldt: Travels to and from Spain Throughout the Centuries / Homenaje a Alexander von Humboldt: Viajes hacia y desde España de todos los siglos

From Humboldt is particularly interesting -and little know- his description of mineral coatings on rocks 200 years ago, reported in his book Personal Narrative of Travels to the Equinoctial Regions of the New Continent during the years 1799-1804, co-written with Aimé Bonpland, for which is considerate the father of rock coating research. On June 5th 1799 set sail from A Coruña -Spain- to Cumaná -Venezuela- beginning five years of expedition. While they explored the Orinoco River system, in th eriver basin waterfalls, Humboldt observed the presence of dark coating depositions. He ascertained a manganese-rich accretion, reporting similar structures in other …

Phosphorus: From The Origins Of Life To The Origin Of An Industry, Joshua Abbatiello

USF Tampa Graduate Theses and Dissertations

The element phosphorus is a key biogenic element that is often the limiting reagent for life. Phosphorus is quickly bound by metal divalent cations making it virtually insoluble and inert in water (forming the phosphate mineral apatite). Due to this, it becomes imperative to understand alternative pathways to increase biogenically available phosphorus in environments. To that end, this dissertation involved examining olivine as an alternative source of phosphorus to apatite, analyzing a novel grain of iron silicide found via lightning reduction in a fulgurite, and finally sought to understand the impact of phosphate mining through phosphogypsum stacks. Olivine is a …

Unveiling The Vital Role Of Blue Carbon In Mangroves: Understanding Environmental Influences, Jahnelle Howe

Dissertations, Theses, and Capstone Projects

Mangrove ecosystems provide essential ecological services, including carbon sequestration, coastal protection, and heavy metal retention. However, their resilience and functionality are increasingly influenced by hurricanes, climate variability, and anthropogenic contamination. This dissertation integrates three research efforts examining mangrove canopy dynamics, carbon storage, and heavy metal contamination in two Puerto Rican mangrove systems: La Parguera and Laguna Grande.

Using remote sensing techniques (LiDAR and NDVI analysis), we assessed the impact of Hurricane Maria (Category 4, 2017) on mangrove canopy structure and vegetation health. Results revealed significant canopy height loss, with greater damage at Laguna Grande, where pre-storm canopy height and human …

Investigating Potential Sugar-Related Uncertainties In A Proxy For Ancient Co2, Liam Cooper

Student Theses and Dissertations

The ε_p proxy for ancient pCO₂ can potentially estimate ancient pCO₂ as from the evolution of rubisco-based photosynthesis, using the difference in stable carbon isotope ratios (δ¹³C) between fixed and inorganic carbon, assuming this difference is proportional to pCO₂. This study aims to address uncertainty with the use of photosynthetic microbes in proxies for ancient pCO₂. While previous studies address uncertainties related to the δ¹³C of initial fixed photosynthate (e.g., growth rate), we aim to address the effects of downstream carbon allocation. Specifically, if a significant fraction of fixed …

Diel Patterns Of Biogeochemical Indicators In Tidally-Dominated Creeks, Juliana Calderone

Honors Theses

Marshes and swashes are vital environments as a controlling barrier between land affected by various pollutants and the ocean. Eutrophication and the effects of this process can be detrimental for the areas experiencing it. I am interested in ways areas that have little contact with human interactions compare to areas that are heavily urbanized, and whether either of these locations is at a higher risk for eutrophication. Using spectrophotometry and fluorometry, I analyzed samples collected from the relatively undeveloped and restricted-access locations of Waities Island Beach and Dunn Sound monthly for dissolved nutrients, and chlorophyll. At the time of sampling, …

The Effect Of Hiv-1 Infection Associated Bacterial Lipopolysaccharide (Lps) On Human Oral Keratinocytes: Implications For Promoting Chronic Inflammation, Md Shafayat Jamil

Theses and Dissertations

Human immunodeficiency virus type 1 (HIV-1) remains a major global health concern, affecting approximately 39 million people worldwide, with 500,000 new infections reported in 2022. While combined antiretroviral therapy (cART) has significantly reduced viral replication, HIV-1 infection is linked to various comorbidities, including oral dysbiosis and accelerated aging. Immune dysregulation in HIV-1–infected individuals promotes the proliferation of pathogenic gram-negative bacteria like Porphyromonas gingivalis, a key contributor to periodontal disease. P. gingivalis secretes lipopolysaccharide (LPS), which adversely affects human oral keratinocytes (HOK), the first line of defense against microbial threats in the oral cavity. HOK recognize LPS as a threat, …

Spatio-Temporal Pattern Of Nutrient Dynamics In The South Texas Coastal Watershed, Mohammad Sadman Alam

Theses and Dissertations

Eutrophication threatens aquatic ecosystems by altering productivity through excessive nutrient inputs. In some systems, primary productivity is limited by nitrogen (N), phosphorus (P), or both, based on the N:P ratio defined by the "Redfield" ratio. South Texas, facing rapid urban growth and industrialization, is at risk of higher nutrient loads, but research on nutrient dynamics in this region is limited. This study investigates nutrient variations in the freshwater (FW) abandoned distributaries of the Rio Grande and hypersaline saltwater (SW) systems. Results showed a significant decrease in dissolved inorganic nitrogen (DIN) and an increase in dissolved inorganic phosphorus (DIP), shifting the …

From Land To Lagoon: The Spatiotemporal Biogeochemical Dynamics Of Arctic Coastal Erosion In Elson Lagoon, Alaska, Sasha Victoria Peterson

Open Access Theses & Dissertations

TThe Arctic is warming rapidly, driving widespread environmental change across coastal landscapes, including permafrost thaw, shoreline erosion, and shifts in sediment and carbon dynamics, pose growing challenges for predicting carbon cycling and climate feedbacks. This dissertation investigates the spatiotemporal variability of erosion, decomposition, and nearshore turbidity in Elson Lagoon, Alaska (1955–2023), to better understand how carbon, nitrogen, and sediment are mobilized, transformed, and potentially emitted as greenhouse gases in Arctic coastal systems. Chapter 2 presents a high-resolution analysis of shoreline change and erosion-driven material fluxes spanning nearly seven decades. Drawing on 795 soil data points, airborne LiDAR, and five shoreline …

08 - Blue Carbon Sequestration And Sediment Storage In Seagrass Meadows Of South Bay, Luke C. Clements, Adriana Amrhein, Richard P. Hale

Undergraduate Research Symposium

Blue carbon is stored in coastal and marine ecosystems like seagrass meadows and salt marshes, which helps combat climate change by preventing greenhouse gas emissions. This study examines the role of seagrass in carbon storage by comparing sediment cores from a mud channel and a seagrass meadow in South Bay.

We collected a 100 cm core from the mud channel and a 55 cm core from the seagrass area, taking samples every 10 cm to analyze grain size and organic carbon content. Using a wet sieving method, we separated sand from mud and measured organic carbon through loss on ignition. …

Meeting Carbon Dioxide Removal Demand In 2030: The Potential Of Macroalgae Cultivation And Harvest, Lotta Siebert, Jiajun Wu, Lena-Katharina Bednarz, David Keller, Felix Meier, Christine Merk, Sonja Peterson, Wilfried Rickels

Journal of Ocean and Coastal Economics

A growing number of countries have announced net-zero and net-negative emissions targets, but only a few countries provide incentives for carbon dioxide removal (CDR). We derive estimates of countries' hypothetical demand for CDR in 2030 based on their emissions reduction targets under the Paris Agreement. The aggregated average global demand for CDR in the compliance year 2030 is 1064 MtCO₂, 353 MtCO₂, and 124 MtCO₂ for the low, medium, and high-cost CDR scenarios, respectively. This demand comes exclusively from countries and regions with relatively high GDP per capita, relatively high abatement costs and a limited …