Biogeochemistry Commons^™

Carbon Dioxide Emissions From Deadwood In Forests Of The Northeastern United States, Zoe Read

Electronic Theses and Dissertations

As the climate changes, understanding the sources and sinks of greenhouse gases such as carbon dioxide (CO₂) is increasingly important. However, several components of the carbon cycle within forests remain poorly understood. For example, knowledge gaps exist in our understanding of CO₂ emissions from coarse woody material (CWM; logs and stumps), including how emissions change over time, how they are influenced by environmental variables, and how they compare to soil and ecosystem-level CO₂ emissions.

To fill these knowledge gaps, we examined CO₂ emissions from CWM at three sites. We sampled 18 red spruce (Picea …

Using Xbeach To Describe The Performance Of An Intertidal Vegetation Shoreline Stabilization Treatment, Elizabeth Winter

Theses and Dissertations

The purpose of this project is to predict the hydrodynamic and morphodynamics of an engineered vegetation-only shoreline restoration project in Little Lagoon, Alabama under different storm and sea level rise scenarios. Little Lagoon is a shallow, single-inlet lagoon located in Baldwin County, Alabama that has been experiencing shoreline erosion for the past 28 years. A living shoreline using vegetation only (Spartina alterniflora) was implemented in the southwest corner of the lagoon, located within Bon Secour National Wildlife Refuge, to create habitat, improve water quality, and prevent future erosion. This research compares “with-project” and “without-project” hydrodynamics and morphodynamics using XBeach in …

The Nitrogen Dynamics Of Deer Cave, Sarawak, And The Role Of Bat Caves As Biogeochemical Sinks In Tropical Moist Forests., Joyce Lundberg, Donald A. Mcfarlane, Guy Van Rentergem

International Journal of Speleology

A better understanding of the role of bat caves as nitrogen sinks in tropical moist forest ecosystems can be expected to shed light on regional and spatial variability in nutrient recycling studies. We measured the nitrogen flux (in air and water) associated with a very large Chaerephon plicata bat colony in Deer Cave, Borneo, in the process generating a new, quantitative, estimate of the total bat population (774,828 ±48,320), and the first detailed modelling of an ammonia plume in a cave. Long-term storage of N does not occur in this wet cave. Our final budget numbers indicate that, of the …

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: …

Manganese Bioavailability Drives Organic Matter Transformations Across Oxic-Anoxic Interfaces Via Biotic And Abiotic Pathways, Nathan A. Chin

Masters Theses

Soil organic matter decomposition is a critical process that affects nutrient cycling, CO₂ emissions, and carbon storage in terrestrial environments. Recent evidence suggests reactive manganese (Mn) phases, potent oxidants that depolymerize compounds like lignocellulose in soil organic matter, act as critical drivers of organic matter decomposition in soil and sediment environments. Furthermore, oxic-anoxic interfaces (OAIs) have been shown to be crucial hotspots for the formation of reactive Mn(III) species and associated organic matter degradation. However, the extent to which microbially mediated Mn(III) formation and subsequently Mn(III)-driven organic matter oxidation depends on Mn availability remains largely unknown. Additionally, the relative …

Evaluating The Impact Of Submarine Groundwater Discharge On Nutrients And Trace Elements In Coastal Systems: The Examples Of The Tuckean Swamp (Australia) And The Mississippi Sound (Usa), Amy Moody

Dissertations

Submarine groundwater discharge (SGD) is the advective flow of both fresh terrestrial groundwater and recirculating seawater through aquifer sediments, which is released into the coastal ocean. In this dissertation, I evaluated the impact of SGD on the distributions and input of trace metals and nutrients. In the Tuckean Swamp, an estuary in Australia dominated by coastal acid sulfate soils, I determined the impact of groundwater on Ba and U during the flood season, when the local aquifer is flushed out after a rapid increase in water table elevation. For Ba and U, groundwater contributed up to 18 and 66 % …

Nutrient Dynamics And Ecosystem Development Of Urban Forests, Gisselle A. Mejía

Dissertations, Theses, and Capstone Projects

Urban growth and expansion are a major component of global environmental change, with impacts on climate, air and water quality, biodiversity, and human well-being. Forests embedded in urban landscapes are critical in mitigating these impacts at local, regional, and continental scales. However, assessing urban forests is difficult because cities are heterogenous in physical, chemical, biological, and social dimensions. This heterogeneity has constrained how urban forests are defined, and therefore, how they are studied. The objective of this dissertation is to determine how these biophysical and social factors drive ecological processes in urban forests and will address three outstanding challenges in …

Exploring The Use Of Covellite As A Proxy For Corrosion Of Native Copper By Sulphur Reducing Bacteria, Manan K. Joshi

Undergraduate Student Research Internships Conference

We are analyzing the effect of sulphate reducing bacteria on native copper, and using that evidence to further support the initiative of having a deep geological repository to store nuclear material. Sulphate reducing bacteria are a concern for the deep geological repository as they cause the corrosion of regular copper. However native copper has gone billions of years without corrosion, which could either mean that it had not been exposed to sulphate reducing bacteria over the billions of years, or native copper is able to withstand corrosion despite the contact of sulphate reducing bacteria. We can find out by trying …

The Paleoecology Of High-Elevation Bison In The Greater Yellowstone Ecosystem And Implications For Modern Bison Conservation, Darian Bouvier

Electronic Theses and Dissertations

The national mammal of the United States, the American Bison (Bison bison) was once nearly extinct. Populations have recovered to the degree that thousands roam the Great Plains today. Due to their large numbers and body size, this species has an oversized impact on the ecological communities where it lives and is considered a keystone herbivore in modern North American grasslands. This study explores the detailed, seasonally resolved, paleoecology of seven bison from the Greater Yellowstone Ecosystem during the Late Holocene through stable isotope analyses and species niche modeling. Isotopic analyses of δ¹³C, δ¹⁵N, …

Manganese Geochemistry And Plant Availability In Response To Agricultural Practices, Ashleigh R. Montgomery

Masters Theses

Manganese (Mn) is an essential micronutrient for all organisms. In soils, Mn forms determine availability to plants. Most Mn research has been conducted in forest ecosystems and Mn cycling in agricultural systems is understudied. Therefore, the objective of the experiment is to understand the effect of different agricultural management strategies on Mn cycling and plant availability. First, a greenhouse experiment was conducted to determine the effect of different application rates of two Mn fertilizers (MnSO₄ and MnEDTA) on soil geochemical properties and growth of corn (Zea mays) and soybean (Glycine max). The fertilizers were applied to …

The Characterization Of Dynamic Soil Properties And Their Relation To Soil Organic Carbon In East Tennessee Soils, Shannon Marissa Newell

Masters Theses

Quantifying how dynamic soil properties (DSPs) are affected by different management regimes is essential for understanding how these vital resources can be better managed. The Dewey soil series is a critical soil series in East Tennessee. For this study, the University of Tennessee, Knoxville (UTK) worked alongside the National Cooperative Soil Survey (NCSS) in an effort to better understand the dynamics of the Dewey soil series through a wide range of DSP data. To accomplish this, Dewey soil was collected from five sites which are considered representative of five management regimes: well-managed cropland (WMC), poorly-managed cropland (PMC), well-managed pasture (WMP), …

Whole Farm Net Zero: Approaches To Quantification Of Climate Regulation Ecosystem Services At The Whole Farm Scale. Vermont Payment For Ecosystem Services Technical Report #7, Christopher Bonasia, Lindsey Ruhl, Benjamin Timothy Dube, Alissa C. White, Heather M. Darby

UVM Extension Faculty Publications

In this report, approaches to the quantification of climate mitigation ecosystem services at the whole farm scale are reviewed and summarized for easy comparison. Eight quantification tools, and three case studies demonstrating possible tool applications, are summarized to fulfill the requirements of the Technical Services Contract—Task 7. Information from a combination of literature review and expert interviews served to document the inputs, outputs, strengths, weaknesses, opportunities, and threats for each quantification tool. This research was conducted in service to the Vermont Soil Health and Payment for Ecosystem Services (PES) Working Group (VT PES working group). It is our hope that …

Understanding Biogeochemical And Physical Controls On Methane Air-Sea Exchange Fluxes In The Pacific Ocean, Sarah Raney

Master's Theses

Methane and trace element samples were collected on GEOTRACES GP15 Pacific Meridional Transect (PMT) cruise conducted between the Aleutian Islands (57 °N) and Tahiti (20 °S) from September to November 2018. Uncertainty in methane air-sea exchange fluxes was determined using a propagation of errors approach. Fluxes ranged from -0.88 to 4.9 µmol CH₄ m^-2 d^-1. Average CH₄ flux along the Alaskan margin was 2.2 ± 2.9 µmol CH₄ m^-2 d^-1. Methane fluxes decreased moving southward and increased to their open ocean maximum around 20 °N before declining in equatorial waters. Near …

Controls On Buffering And Coastal Acidification In A Temperate Estuary, Christopher W. Hunt, Joseph Salisbury, Douglas Vandemark

Faculty Publications

Estuaries may be uniquely susceptible to the combined acidification pressures of atmospherically driven ocean acidification (OA), biologically driven CO2 inputs from the estuary itself, and terrestrially derived freshwater inputs. This study utilized continuous measurements of total alkalinity (TA) and the partial pressure of carbon dioxide (pCO2) from the mouth of Great Bay, a temperate northeastern U.S. estuary, to examine the potential influences of endmember mixing and biogeochemical transformation upon estuary buffering capacity (β–H). Observations were collected hourly over 28 months representing all seasons between May 2016 and December 2019. Results indicated that endmember mixing explained most of the observed variability …

A Remote Sensing And Machine Learning-Based Approach To Forecast The Onset Of Harmful Algal Bloom (Red Tides), Moein Izadi

Dissertations

In the last few decades, harmful algal blooms (HABs, also known as “red tides”) have become one of the most detrimental natural phenomena all around the world especially in Florida’s coastal areas due to local environmental factors and global warming in a larger scale. Karenia brevis produces toxins that have harmful effects on humans, fisheries, and ecosystems. In this study, I developed and compared the efficiency of state-of-the-art machine learning models (e.g., XGBoost, Random Forest, and Support Vector Machine) in predicting the occurrence of HABs. In the proposed models, the K. brevis abundance is used as the target, and 10 …

Honey As A Biomonitor For Air Pollutant Deposition In The Eastern United States Using Ion Chromatography And Scanning Electron Microscopy, Cole Cochran

Undergraduate Honors Theses

Anthropogenic activities generate metal, acid, and particulate air pollutants which negatively impact human and ecological health. In the United States, power plant, industrial, and vehicle emissions are leading causes of air pollution, however, the measurement of air pollution at high-resolution spatial regimes remains a challenge. Honey has emerged as a powerful biomonitoring tool to effectively quantify contaminants without the need for a large array of monitoring instruments. I hypothesized that honey could be used to effectively measure and map modern air pollutant spatiotemporal relationships over the Eastern U.S. Using ion chromatography with sulfate as an indicator for air pollution and …

Inverse Modeling Of Atmospheric Ch4 And Δ13C-Ch4 Measurements From Surface Observation Sites To Understand Trends In Global Methane Emissions Over More Than Three Decades, Sayantani Karmakar

Dissertations and Theses

Methane (CH₄) is the second most important greenhouse gas with a radiative forcing of 0.97 W/m² including both direct and indirect effects and a global warming potential of 28 over a 100-year time horizon. Unlike CO₂ whose rate of growth in the atmosphere has remained positive and increased in recent decades, the behavior of atmospheric methane is considerably more complex and is much less understood on account of the spatiotemporal variability of its emissions which include biogenic (e.g., wetlands, ruminants, rice agriculture), thermogenic (fossil fuels), and pyrogenic (i.e., biomass burning) sources. After sustained growth during most …

Stable Isotope Analysis Of A Platecarpus Tympaniticus (Squamata, Mosasauridae) With Actinocamax Sternbergi (Mollsuca, Belemnoidea) Reveals Possible Endothermic Thermoregulation, Mitchell Lukens

Master's Theses

Mosasaurs, ancient marine reptiles, dominated the late Cretaceous oceans. However, their ecological success is a contentious topic. Were they ectothermic, like their modern relatives the varanid lizards? Or endothermic like extant marine mammals? Stable isotopes can reveal temperature and physiological variances within skeletons, but do not differentiate between body temperature and ambient environmental temperature. A rare mosasaur specimen from the Smoky Hill Chalk of a partial, articulated Platecarpus tympaniticus with stomach contents of belemnites provides a possible direct temperature contrast between predator and prey. The belemnites, related to modern coleoids, are identified as Actinocamax sternbergi. These animals possessed body …

Controls On Carbon Gas Fluxes From A Temperate Forest Soil, Natalie A. White, Ruth K. Varner, Clarice R. Perryman

Honors Theses and Capstones

Forest soils consume atmospheric methane (CH₄), serving as a major global CH₄ sink that uptake an estimated 22 ± 12 Tg of CH₄ per year. Temperature and soil moisture have been identified as key controls of the microbial consumption of CH₄ in forest soils. Climate-driven warming and changing moisture regimes may impact forest soils’ role in the carbon cycle, and recent works suggests that forests could become weaker CH₄ sinks. Long-term monitoring sites can capture these changes, leading to better predictions of CH₄ exchange between the atmosphere and soils under climate change. This study …

Drivers And Seasonal Variability Of Redox-Sensitive Metal Chemistry In A Shallow Subterranean Estuary, Alison E. O'Connor, Elizabeth A. Canuel, Aaron J. Beck

VIMS Articles

The subterranean estuary (STE) has been historically defined in terms of the mixing of saline and fresh water, in an analogy to surface estuaries. However, redox gradients are also a defining characteristic of the STE and influence its role as a source or sink for metals in the environment. Approaching the STE from a redox-focused biogeochemical perspective (e.g., considering the role of microbial respiration and availability of organic matter) provides the ability to quantify drivers of metal transport across spatial and temporal scales. This study measured the groundwater composition of a shallow STE over 2 years and used multiple linear …