Biogeochemistry Commons^™

Quantifying Co2 And Ch4 Fluxes In A Semi-Arid Floodplain: Assessing Spatial And Temporal Drivers, Miles E. Kelsey

Earth and Planetary Sciences ETDs

Rivers transport sediment and carbon across Earth’s surface, and their floodplains can store carbon over decades to millennia, making them important to terrestrial carbon management. While soil carbon can persist long term, it may be released as greenhouse gases through processes like methanogenesis and heterotrophic respiration. Environmental controls on these fluxes remain poorly constrained across floodplains in different climate and geomorphic setting, but especially in semi-arid systems where measurements are limited. To address this gap, we quantified CO₂ and CH₄ fluxes along the Middle Rio Grande (New Mexico, USA) using 227 chamber measurements collected May to November 2025 at three …

Biogeochemical Controls On Phosphorus Transport And Legacy Storage Across A Coastal Watershed, Lee Potter

LSU Doctoral Dissertations

Excess phosphorus (P) loading is a key driver of eutrophication and harmful algal blooms (HABs) in aquatic systems worldwide. This relationship is of increasing concern in coastal Louisiana, where climate variability, altered hydrology, and land-use change converge, resulting in increased hydrologic and nutrient loading into coastal systems. This dissertation examines controls on P cycling in the Lake Pontchartrain Basin through a multi-scale framework linking estuarine processes, watershed loading, climate and weather patterns, and sediment dynamics. The dissertation begins with an overview of the study region, P dynamics, and changes in hydrology and nutrient loading patterns. Chapter 2 presents a spatial …

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 …

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 …

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. …

Tracing The Sources Of Nitrogen In Submarine Groundwater Discharge And Primary Producers In The Great South Bay Estuary, Nia H. Rene

Dissertations, Theses, and Capstone Projects

The primary aim of this research was to elucidate the impact of submarine groundwater discharge (SGD) and septic effluent on coastal primary producers in the Great South Bay (GSB). The study focused on three main objectives: assessing the impact of precipitation patterns on SGD, tracing nitrogen sources into the GSB, and determining the impact of these nitrogen sources on coastal primary producers. The research revealed that current precipitation patterns significantly influence SGD across different seasons, highlighting the seasonal variability in groundwater discharge and its implications for nutrient loading in coastal waters. A suite of tracers was employed to identify and …

Unveiling Hidden Mercury And Methylmercury Sources: The Role Of Submarine Groundwater Discharge In Coastal Lagoons, Céline Lavergne, Júlia Rodriguez-Puig, Clara Ruiz-González, Maria Montero-Curiel, Gemma Casas, Daniel Romano-Gude, Irene Alorda-Montiel, Júlia Dordal-Soriano, Aaron Alorda-Kleinglass, Marc Diego-Feliu, Javier Gilabert, Alex Campillo-De La Maza, Cristina Romera-Castillo, Natalia Torres-Rodriguez, Lars-Eric Heimbürger-Boavida, Jordi Garcia-Orellana, Valenti Rodellas, Andrea G. Bravo

OES Faculty Publications

Mercury loads from Submarine Groundwater Discharge (SGD) may represent an overlooked source of methylmercury (MeHg) to the ocean, affecting human and ecosystem health. The SGD process involves the flow of fresh, saline, or mixed groundwater from coastal aquifers into the oceans classified in different components. Existing studies rarely report the fluxes supplied by the different SGD components; therefore, the relevance of SGD as a source of mercury remains unclear. We aimed to quantify SGD-driven mercury/methylmercury fluxes to the coast, focusing on the largest coastal lagoon in the western Mediterranean. We measured total dissolved mercury and MeHg in surficial and porewaters …

Impacts Of Southern Pine Beetle (Dendroctonus Frontalis Zimmerman) On Loblolly Pine (Pinus Taeda L.) Canopy And Water Use In The Homochitto National Forest, Mississippi, Usa, Sasha Goodnow, Yun Yang, Hui Liu, Ashley Schulz

Endeavors: Mississippi State Undergraduate Research Journal

Abiotic and biotic forest disturbances can have many impacts to forest ecosystem services, including to forest water use. Studies on impacts to forest evapotranspiration have been conducted on the mountain pine beetle (Dendroctonus ponderosae) in western North America, but not on the southern pine beetle (Dendroctonus frontalis), which is a native pest of loblolly pine (Pinus taeda) and shortleaf pine (Pinus echinata), in the southeastern United States. Stressed pine trees produce pheromones that attract southern pine beetles and, with enough stressed trees, beetle populations can quickly grow to epidemic levels and attack healthy trees, which results in widespread tree mortality. …

A Collaborative Assessment Of Coastal Ocean Acidification Monitoring In Maine & Standard Operating Procedures And Best Practices For The Collection Of Continuous Ph Data In Coastal Marine Environments, Christopher W. Hunt, Curtis Bohlen, Mike Doan, Jeremy Miller

Faculty Publications

The ‘Sensor Squad’ of the Maine Ocean Climate Collaborative is the product of a 2023 Maine Coastal and Marine Climate Action Fund grant to conduct “A two-year pilot project designed to address and overcome technological barriers to ocean acidification data collection, develop protocols to elevate quality assurance and ensure comparable data, and meet regularly to discuss project results and data compilation”. The Squad consists of representatives from Friends of Casco Bay (FOCB), Wells National Estuarine Research Reserve (WNERR), and the University of New Hampshire (UNH). This report is a summary of their efforts to assess affordable, repeatable means of continuously …

Investigating The Thermal Stratification Patterns Of A Shallow Polymictic Boreal Shield Lake And The Effectiveness Of Models In Predicting Shallow Lake Thermal Profiles, Matthew Roberts

Theses and Dissertations (Comprehensive)

Thermal stratification is a core process of lakes which plays a critical role in shaping the ecological dynamics of lakes, influencing major processes like nutrient cycling and oxygen availability. For shallow polymictic lakes, thermal stratification patterns present some unique differences due to the complex and variable nature of these lakes. In this thesis, I examined thermal stratification in a shallow polymictic lake in northwestern Ontario during the ice-free season of 2019 to investigate the frequency, duration, and driving factors of thermal stratification. The lake underwent 146 separate stratification events, with a median duration of 2 hours per event, with a …

Effects Of Urbanization On Eutrophication Parameters In Three Tidal Creeks, Ella Swantek

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, …

Impacts Of Hurricane Idalia’S Surge On Coastal Sand Biogeochemistry, Wendy "Cor" Mchone

Honors Theses

Beaches are heavily influenced by extreme events, such as hurricanes. Biological and chemical processes, such as primary production and diagenesis are often interrupted by these events. To examine the effects of hurricanes on coastal biogeochemistry, this study used sand and porewater samples from Waties Island, SC, which were collected before and after Hurricane Idalia. The samples were analyzed for macronutrient concentrations, organic content, and chlorophyll concentrations. Macronutrient pore water concentration changes were not uniform. The inventory of nitrite decreased significantly after the storm, which was reflected in slight increases in the inventories of nitrate and ammonium. Concentrations of nitrate, which …

Sedimentary Conditions At A Tidal Creek That Exhibits Seasonal Pelagic-Benthic Variations, Jack B. Corbin

Honors Theses

Tidal creeks in the Grand Strand of South Carolina are small but numerous connectors between land and ocean. One of these creeks, White Point Swash, exhibits a seasonal switch between planktonic and benthic photosynthesizers. As plankton become less abundant in fall, benthic macroalgae bloom, aided by lower water levels due to fall-winter dredging of the main channel, until late Spring. This study builds on previous findings and examines sedimentary conditions at this site further. Sedimentary chlorophyll a (in microphytobenthos) and pore water nutrient concentrations are confirmed to be higher than water-column concentrations. Sedimentary nutrient fluxes to the sediment-water interface, calculated …

Evaluating The Risk Posed By Gadolinium In The Grand River Watershed, Johann Memmel

Theses and Dissertations (Comprehensive)

Gadolinium (Gd) is a rare earth element (REE), primarily used in contrast agents for magnetic resonance imaging (MRI), with additional applications in metallurgy, phosphors, neutron shielding, and other niche applications. Both Gd and Gd-based contrast agents (GBCAs, the form used for MRIs) have been detected downstream of wastewater effluent discharges and there is currently little research into the risk this poses to aquatic ecosystems. This study investigated the potential environmental risks of Gd and GBCAs using the Grand River watershed (GRW) in southwestern Ontario as a model ecosystem due to it containing a variety of land uses (urban, industrial, agricultural) …

Assessing Stormwater Management Pond Water Quality, Function, And The Potential Biotic Effects To Receiving Waters, Mitchell Elstone

Theses and Dissertations (Comprehensive)

The use of stormwater management ponds (SWMPs) has been increasing over the past five decades. However, an in-depth understanding of the daily performance of SWMPs and functionality during cold periods is limited. This is in part because mandated monitoring is relatively infrequent, and the assumption that SWMPs are inactive between storm events and during the winter. The goals of this research were to better understand daily stormwater (SW) characteristics, the performance of SWMPs based on current forms of evaluation and assess the potential for SWMP effluent to impact downstream biota. Influent and effluent samples from two SWMPs were collected daily …

Reducing Food Scarcity: The Benefits Of Urban Farming, S.A. Claudell, Emilio Mejia

Journal of Nonprofit Innovation

Urban farming can enhance the lives of communities and help reduce food scarcity. This paper presents a conceptual prototype of an efficient urban farming community that can be scaled for a single apartment building or an entire community across all global geoeconomics regions, including densely populated cities and rural, developing towns and communities. When deployed in coordination with smart crop choices, local farm support, and efficient transportation then the result isn’t just sustainability, but also increasing fresh produce accessibility, optimizing nutritional value, eliminating the use of ‘forever chemicals’, reducing transportation costs, and fostering global environmental benefits.

Imagine Doris, who is …

High-Energy Storm Events And Their Impacts On Carbon Storage In Tidal Wetlands Of South Carolina, Gavin Gleasman

All Dissertations

Atmospheric carbon dioxide (CO₂) concentrations have been increasing at an accelerating rate for the past two centuries, profoundly impacting global climate change. Atmospheric CO₂ concentrations are influenced by the global carbon cycle through physical and biogeochemical pathways. Tidal wetland environments play a vital role in the global carbon cycle by offsetting atmospheric CO₂ concentrations through their natural physiochemical processes of high autotrophic productivity, allochthonous organic matter deposition, anoxic soils, and continuous accretion which promotes carbon sequestration with long-term storage at the land-ocean margin. The Intergovernmental Panel on Climate Change (IPCC) and United States Global Change Research …

Small Community Water Systems Have The Highest Prevalence Of Mn In Drinking Water In California, Usa, Miranda Aiken, Samantha C. Ying

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Manganese (Mn) is currently regulated as a secondary contaminant in California, USA; however, recent revisions of the World Health Organization drinking water guidelines have increased regulatory attention of Mn in drinking water due to increasing reports of neurotoxic effects in infants and children. In this study, Mn concentrations reported to California’s Safe Drinking Water Information System were used to estimate the potentially exposed population within California based on system size. We estimate that between 2011 and 2021, over 525,000 users in areas with reported Mn data are potentially exposed to Mn concentrations exceeding the WHO health-based guideline (80 μg L …

The Dynamics Of Sedimentary Chlorophyll Α At A High-Energy Beach, Sarah (Gray) Abel

Honors Theses

Productive sandy beaches are one of the most crucial areas serving our ecosystem today. While often overlooked in scientific research, productive beaches have many essential functions that lead to the preservation and protection of many different species as well as ecological wellness and stability. A key factor that is linked to this productivity is the presence of chlorophyll in the sediments. Piston cores of the sediments at the low-tide mark at Waties Island, South Carolina, were collected across multiple years and subsequently analyzed for chlorophyll concentrations through fluorometry after acetone extraction and acidification. Each core profile was processed to calculate …

Investigation Of A Possible Switch Of Benthic Photosynthetic Organisms And Phytoplanktonic Organisms In White Point Swash, South Carolina, Nathan Easterling

Honors Theses

This research study examined the possible switch from benthic photosynthetic organisms to phytoplankton in the water column at White Point Swash, Long Bay, South Carolina, and what is causing this switch to occur. During Dr. Hannides’ and his group’s studies at this and other swashes in the past, they noticed this phenomenon of the benthic photosynthetic organisms taking over during a certain time and then the phytoplankton in the water column taking over during a different time. In this study, I measured the relative benthic macroalgal area coverage and sedimentary chlorophyll a concentration as measures of the abundance of benthic …

Suboxic And Anaerobic Respiration Across A Sandy-Shore-To-Estuarine Gradient, Jacey Ballard

Honors Theses

Sulfate is an inorganic ion that is one of the major ions of seawater. Sulfate is also an essential reactant in microbially mediated anaerobic respiration that produces sulfide, an energy source during chemosynthesis. Sulfide is widely found in sediment, and water rich in decaying organic material, as well as hydrothermal vents. While sulfate reduction occurs extensively in muds, such as those of marshes, it is not expected to occur in sand which is much better aerated. Recent research in our group documented extensive sub aerobic respiration in coastal sands which suggests that sulfate reduction may have also been happening. This …

Rapid Bacterial And Fungal Successional Dynamics In First Year After Chaparral Wildfire, M. Fabiola Pulido-Chavez, James W. J. Randolph, Cassandra A. Zalman, Loralee Larios, Peter M. Homyak, Sydney I. Glassman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The rise in wildfire frequency and severity across the globe has increased interest in secondary succession. However, despite the role of soil microbial communities in controlling biogeochemical cycling and their role in the regeneration of post-fire vegetation, the lack of measurements immediately post-fire and at high temporal resolution has limited understanding of microbial secondary succession. To fill this knowledge gap, we sampled soils at 17, 25, 34, 67, 95, 131, 187, 286, and 376 days after a southern California wildfire in fire-adapted chaparral shrublands. We assessed bacterial and fungal biomass with qPCR of 16S and 18S and richness and composition …

Concentration Of Heavy Metals In Three Distinct Algae Families From Humboldt County, California, Kodiak E. Miller, Caleb J. Strait, Jacob I. Begorre, Brittney L. Mitchell, Claire P. Till

IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt

Anthropogenic impacts on marine environments can impact metal fluxes and concentrations available to marine species. Monitoring these impacts is necessary to better understand the interactions between the biotic and abiotic components of these ecosystems and mitigate the risk posed by harmful toxins introduced by human activities. Biomoniters, like macroscopic algae, are useful indicators that illuminate the bioaccumulation of toxins commonly introduced from anthropogenic activity. With this in mind, the concentrations of heavy metals zinc (Zn), nickel (Ni), and copper (Cu) were analyzed via the assessment of algae (Representatives from Ulva, Mastocarpus, Fucus) in two sites in Humboldt County: …

The Interaction Of Different Primary Producers And Physical And Chemical Dynamics Of An Urban Shallow Lake, Majid Sahin

Dissertations, Theses, and Capstone Projects

An artificial urban shallow lake, Prospect Park Lake (PPL), is situated on a terminal moraine in Brooklyn New York, and supplied with municipal water treated with ortho-phosphates. The constant input of the phosphate nutrient is the primary source of eutrophication in the lake. The numerous pools along the water course houses various aquatic phototrophs, which influence the water quality and the state of the system, driving conditions into favoring the survival of their species. In the first half of the dissertation, the focus of the project is on analyzing how the different primary producers in different regions of PPL affect …

Determining The Effects Of Elevated Carbon Dioxide On Soil Acidification, Cation Depletion, And Soil Inorganic Carbon And Mapping Soil Carbons Using Artificial Intelligence, Jannatul Ferdush

Theses and Dissertations

Soil carbon is the largest sink and source of the global carbon cycle and is disturbed by several natural, anthropogenic, and environmental factors. The global increase of atmospheric CO₂ affects soil carbon cycling through varied biogeochemical processes. The first chapter is a compilation of current information on potential factors triggering soil acidification and weathering mechanisms under elevated CO₂ and their consequences on soil inorganic carbon (SIC) pool and quality. Soil water content and precipitation were critical factors influencing elevated CO₂ effects on the SIC pool. The second chapter examines a detailed column experiment in which six soils …

Iron Geochemistry Across An Estuary-To-Coastal Gradient, Lissett G. Diaz

Honors Theses

Iron is a ubiquitous earth element that participates in biogeochemical processes that occur in marine sediments. Microorganisms utilize iron for many purposes, including cell growth, conserving energy, and for maintaining metabolic activity. In coastal sedimentary settings, understanding the redox reactions involving ferric iron, Fe³⁺, and ferrous iron, Fe²⁺, in its solid phase and pore-water phases, respectively, enable an appreciation of biogeochemical transformations occurring in the coastal zone. In this study, iron concentrations in sediment of ranging permeability were determined at four stations marking an estuary-coast transition zone in Singleton Swash in Myrtle Beach, South Carolina. The …

The Variability Of Seawater Carbonate Chemistry In Two Florida Urban Mangrove Ecosystems, Alexandrina R. Rangel

All HCAS Student Capstones, Theses, and Dissertations

Anthropogenic carbon dioxide (CO₂) emissions into the atmosphere are yielding serious impacts across the world’s ocean, including ocean acidification, sea level rise, and increasing seawater temperature. However, these changes are not occurring uniformly across all marine ecosystems. Coastal ecosystems, such as mangroves, already experience extreme and variable environmental conditions due to natural biogeochemical and physical processes. The goal of this study was to document small-scale variability in two urban mangrove ecosystems to gain insight into how ocean acidification will manifest within these systems. Using a stand-up paddleboard, a suite of sensors, and traditional bottle sampling techniques, we measured …

Net Geochemical Release Of Base Cations From 25 Forested Watersheds In The Catskill Region Of New York, Sara C. Nieman, Chris E. Johnson

Civil and Environmental Engineering - All Scholarship

Chemical weathering of minerals is the principal mechanism by which base cations (Ca²⁺, Mg²⁺, K⁺, and Na⁺) are released and acidity is neutralized in soils, bedrock and drainage waters. Quantifying the release of base cations from watershed soils is therefore crucial for the calculation of “critical loads” of atmospheric acidity to forest ecosystems. We used a mass-balance approach to estimate the rate of release of base cations in 25 headwater catchments in the Catskill region of New York, an area historically subject to high inputs of acid deposition. In 2010-2013, total net …

An Integrative Model For Soil Biogeochemistry And Methane Processes: I. Model Structure And Sensitivity Analysis, Daniel M. Ricciuto, Xiaofeng Xu, Xiaoying Shi, Yihui Wang, Xia Song, Christopher W. Schadt, Natalie A. Griffiths, Jiafu Mao, Jeffrey M. Warren, Peter E. Thornton, Jeff Chanton, Jason K. Keller, Scott D. Bridgham, Jessica Gutknecht, Stephen D. Sebestyen, Adrien Finzi, Randall Kolka, Paul J. Hanson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Environmental changes are anticipated to generate substantial impacts on carbon cycling in peatlands, affecting terrestrial-climate feedbacks. Understanding how peatland methane (CH₄) fluxes respond to these changing environments is critical for predicting the magnitude of feedbacks from peatlands to global climate change. To improve predictions of CH₄ fluxes in response to changes such as elevated atmospheric CO₂ concentrations and warming, it is essential for Earth system models to include increased realism to simulate CH₄ processes in a more mechanistic way. To address this need, we incorporated a new microbial-functional group-based CH₄ module into the Energy …