The Effects Of Legacy Sulphur Deposition On Methylmercury Production In Northern Peatlands; Geochemical And Biological Considerations, 2020 The University of Western Ontario
The Effects Of Legacy Sulphur Deposition On Methylmercury Production In Northern Peatlands; Geochemical And Biological Considerations, Jennifer L. Blythe
Electronic Thesis and Dissertation Repository
Mercury is a ubiquitous element with a complex geochemical cycle. Aquatic ecosystems such as wetland soils convert inorganic mercury to organic, neurotoxic methylmercury though the activity of sulphate-reducing bacteria (SRB). Sulphate stimulates the activity of SRB, and the production of methylmercury in these environments. My aim was to investigate the effect that legacy sulphate has on Hg methylation in northern peatlands through a laboratory sulphate addition experiment with differentially sulphate-exposed peats and a field study of peatlands subjected to different levels of sulphate. Results from the laboratory study indicate that peatlands in regions of higher atmospheric sulphate deposition show enhanced …
Carbon Use Efficiency And Its Temperature Sensitivity Covary In Soil Bacteria, 2020 University of Massachusetts Amherst
Carbon Use Efficiency And Its Temperature Sensitivity Covary In Soil Bacteria, Grace Pold, Luiz A. Domeignoz-Horta, Eric W. Morrison, Serita D. Frey, Seeta A. Sistla, Kristen M. Deangelis
Faculty Publications
The strategy that microbial decomposers take with respect to using substrate for growth versus maintenance is one essential biological determinant of the propensity of carbon to remain in soil. To quantify the environmental sensitivity of this key physiological trade-off, we characterized the carbon use efficiency (CUE) of 23 soil bacterial isolates across seven phyla at three temperatures and with up to four substrates. Temperature altered CUE in both an isolate-specific manner and a substrate-specific manner. We searched for genes correlated with the temperature sensitivity of CUE on glucose and deemed those functional genes which were similarly correlated with CUE on …
Ecosystem Health In Guánica Bay And La Parguera, Puerto Rico: Remote Sensing Of Ocean Color And Metal Analysis Of Coral Tissue And Surficial Sediments, 2020 CUNY City College
Ecosystem Health In Guánica Bay And La Parguera, Puerto Rico: Remote Sensing Of Ocean Color And Metal Analysis Of Coral Tissue And Surficial Sediments, Jahnelle Howe
Dissertations and Theses
Guánica Bay is an estuary located in southwest Puerto Rico, with a coral reef ecosystem at its periphery. This ecosystem is affected by sediments, nutrients, and contaminants from the watershed through the Bay and into the offshore water. This project evaluates Guánica Bay and La Parguera coastal areas through remote sensing and chemical analysis to assess coastal ecosystem health. The concentration of metals in two coral species and their associated surface sediments was were analyzed by X-ray fluorescence (XRF) and Direct Mercury Analyzer (DMA- 80). Ocean color remote sensing was used to estimate nutrient inputs and phytoplankton biomass through chlorophyll- …
Age-Specific And Species-Specific Tree Response To Seasonal Drought In Tropical Dry Forests, 2020 Cal Poly Humboldt
Age-Specific And Species-Specific Tree Response To Seasonal Drought In Tropical Dry Forests, Emily A. Santos
Cal Poly Humboldt theses and projects
Millions of people live in or depend on ecoregions dominated by Tropical Dry Forests (TDFs), but due to their high accessibility, convenient topography and mild climate conditions their distribution is fragmented with less than 10% of their original extent remaining in many countries. Despite the vast ecosystem services provided by TDFs, including vital water resources in water limited environments, ecohydrological research in this biome has been limited to a small number of short-term investigations. Similar to worldwide trends, the TDF surrounding Bahía de Caráquez (Bahía), Ecuador, has been severely deforested over the past 400 years. The land use history in …
Understanding And Measuring Net Positive Business Strategies, 2020 University of Montana
Understanding And Measuring Net Positive Business Strategies, Luke Ruffner Robinson
Graduate Student Theses, Dissertations, & Professional Papers
Despite their attempts to mitigate ecological impacts through sustainability initiatives, businesses are a major cause of the world's ecological problems. Some progressive businesses are attempting to move beyond “net zero” in terms of achieving neutral environmental impacts and instead are now pursuing a goal of net positive. Net positive refers to the idea that business activities could contribute value-added benefits to earth’s ecological systems, for example, by using technologies that sequester and store carbon. However, except for a handful of high-profile corporate case studies, little is known about how companies are developing their strategies to become net positive and …
Comparison Of Fe(Iii) Reduction Rates By Iron-Reducing Bacteria Within Sub Muros Samples From Quadrilátero Ferrífero Iron-Ore Caves, Brazil, 2020 The University of Akron
Comparison Of Fe(Iii) Reduction Rates By Iron-Reducing Bacteria Within Sub Muros Samples From Quadrilátero Ferrífero Iron-Ore Caves, Brazil, Summer Ellis
Williams Honors College, Honors Research Projects
Previous research investigating the speleogenesis of iron-ore caves (IOC) in the Quadrilátero Ferrífero, or “Iron Quadrangle,” of Brazil suggests that microbial iron reduction and subsequent dissolution of the surrounding Fe(III) rich rocks is responsible for cave formation. A soft intra-wall substance (sub muros) containing iron-reducing bacteria (FeRB) was discovered underneath the durable crusts of cave walls. The goal of the study was to determine if reduction rates were comparable between sub muros samples, while additionally observing how different electron donors affect microbial iron reduction. To do this, I compared Fe(III) reduction rates between sub muros samples collected from …
Using Satellite Observations Of Soil Moisture To Improve Modeling Of Terrestrial Water Cycles, 2020 University of Montana
Using Satellite Observations Of Soil Moisture To Improve Modeling Of Terrestrial Water Cycles, Colin W. Brust
Graduate Student Theses, Dissertations, & Professional Papers
Terrestrial evapotranspiration (ET) describes the flux of water from the Earth’s surface to the atmosphere, calculated as the sum of evaporation from soil and leaf surfaces, and transpiration through plant stomata. ET is the largest terrestrial water flux, returning over half of the precipitation that falls on land back to the atmosphere, annually. Additionally, ET plays a key role in Earth’s carbon, water, and energy cycles, linking them together via the movement of water and CO2 through plant stomata. Because of its important role in these Earth system processes, it is essential that existing methods of measuring and modeling …
Impacts Of Fertilization On Salt Marsh Resilience: Altered By Location-Specific Drivers, 2020 William & Mary - Virginia Institute of Marine Science
Impacts Of Fertilization On Salt Marsh Resilience: Altered By Location-Specific Drivers, Kenneth Michael Czapla
Dissertations, Theses, and Masters Projects
Salt marshes provide valuable ecosystem services to human society, but are currently under threat from accelerating sea level rise and nutrient enrichment. Carbon (C) and mineral accumulation allow salt marshes to maintain elevation above sea level and survive. Anthropogenic nitrogen (N) loading is increasing in many salt marshes, causing negative impacts on marsh resilience such as increased decomposition and decreased below-ground production. However, increasing N may also have simultaneous positive effects such as increased primary production and above-ground biomass, surface sediment accretion, and denitrification rates, which remove excess N from coastal waters. Many studies have been conducted to determine the …
Reconstructing Hydrologic Conditions And Metals Supplied By The Peace River To The Peace-Athabasca Delta, 2020 Wilfrid Laurier University
Reconstructing Hydrologic Conditions And Metals Supplied By The Peace River To The Peace-Athabasca Delta, Jelle André Faber
Theses and Dissertations (Comprehensive)
The Peace-Athabasca Delta (PAD) in northern Alberta, Canada, is recognized internationally for its ecological, historical, and cultural significance. The delta is mostly within Wood Buffalo National Park, a UNESCO World Heritage Site, and is a Ramsar Wetland of International Importance. The construction of the WAC Bennett Dam (1967) and the Site C Dam (ongoing, 2024) on the Peace River, and expansion of the Alberta Oil Sands industry along the Athabasca River have raised concerns over water quantity and quality in the delta. When industry operations began, effective monitoring had not been implemented. Consequently, pre-industrial reference conditions are unknown and can …
Investigating Diel, Seasonal, And Interannual Variability Of Dissolved And Particulate Stable Carbon Isotope Values In A Eutrophic Boreal Lake, 2020 Wilfrid Laurier University
Investigating Diel, Seasonal, And Interannual Variability Of Dissolved And Particulate Stable Carbon Isotope Values In A Eutrophic Boreal Lake, Rachel Henderson
Theses and Dissertations (Comprehensive)
Lakes are globally significant sources, sinks, and conduits of carbon. Cultural eutrophication of freshwater promotes the growth of phytoplankton blooms, which can transform, respire, and sequester large amounts of carbon. Analysis of stable carbon isotopes is a common tool to study the movement of carbon through the aquatic carbon cycle. The causes of temporal variability in δ13C values at different timescales are not well understood, and differ between lakes. In this study, I investigated diel, seasonal, and interannual variability in δ13C values of dissolved inorganic carbon (DIC) and particulate organic carbon (POC) in Lake 227, an …
Dissolved Organic Matter Movement Across Lake Superior’S Terrestrial-Stream-Coastal Interface, 2020 Michigan Technological University
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 …
Microdialysis: A Method For Quantifying In Situ Nitrogen Fluxes In Soil Microsites, 2020 University of Arkansas, Fayetteville
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 …
Estimating Carbon Flux From Optically Recording Total Particle Volume At Depths Below The Primary Pycnocline, 2019 Old Dominion University
Estimating Carbon Flux From Optically Recording Total Particle Volume At Depths Below The Primary Pycnocline, Alexander B. Bochdansky, Robert B. Dunbar, Dennis A. Hansell, Gerhard J. Herndl
OES Faculty Publications
Optical instruments can rapidly determine numbers and characteristics of water column particles with high sensitivity. Here we show the usefulness of optically assessed total particle volume below the main pycnocline to estimate carbon export in two systems: the open subarctic North Atlantic and the Ross Sea, Antarctica. Both regions exhibit seasonally high phytoplankton production and efficient export (i.e., a strong biological pump). Total particle volumes in the mesopelagic (200-300 m) were significantly correlated with those in the overlying surface mixed layer (50-60 m), indicating that most particles at depth reflect export from the surface. This connectivity, however, is modulated by …
The Effects Of Sediment Acidification And Temperature On The Immune Capacity Of The Atlantic Jackknife (Razor) Clam (Ensis Leei M. Huber, 2015), 2019 University of Maine
The Effects Of Sediment Acidification And Temperature On The Immune Capacity Of The Atlantic Jackknife (Razor) Clam (Ensis Leei M. Huber, 2015), Brian Preziosi
Electronic Theses and Dissertations
Sediment acidification has been shown to negatively impact clams of economic importance such as the soft-shell clam, Mya arenaria Linnaeus, 1758, and hard clam, Mercenaria mercenaria (Linnaeus, 1758). Effects of sediment acidification on razor clams, including the Atlantic jackknife clam Ensis leei M. Huber, 2015, are unknown. E. leei has been identified as a species with potential for aquaculture operations on the New England coast. E. leei may be resilient to acidification and thus persist in acidified sediments where other clams cannot. To this end, the impact of acidified surface sediment on the internal immune capacity of adult (mean shell …
Pesticide Seed Treatments Containing Neonicotinoids Have Limited Effect On Soil Microbial Community Structure Under Different Tillage Regimes, 2019 University of New Hampshire, Durham
Pesticide Seed Treatments Containing Neonicotinoids Have Limited Effect On Soil Microbial Community Structure Under Different Tillage Regimes, Jessica E. Mackay, Richard G. Smith, Jessica G. Ernakovich, Lukas T. Bernhardt
Faculty Publications
Pesticide seed treatments (PST) which contain fungicides and insecticides are commonly used in agriculture; however, little is known about their effect on soil microbial communities and soil health. Neonicotinoids – controversial insecticides which are common in PST – have received criticism due to potential non-target effects. While fungal pathogens need to be moderated, PST have the potential to disturb broader fungal communities which could lead to reduced nutrient cycling and poor soil health. Given the broad use of PST, their effect on soil fungi needs to be studied within the context of other agricultural management practices. For example, tillage regimes …
Reconstructing Energy Flow Through Modern And Historical Marine Communities: Insights From Amino Acid Isotope Analysis, 2019 University of New Mexico
Reconstructing Energy Flow Through Modern And Historical Marine Communities: Insights From Amino Acid Isotope Analysis, Emma A. Elliott Smith
Biology ETDs
The fundamental currency of life is energy. Organisms need energy to grow, to survive and to reproduce. Understanding the acquisition of energy by consumers is thus a foundational aspect of biological research. This is especially important in the modern era, as impacts of ongoing anthropogenic effects will be mediated or amplified through food webs. Here, I explore how isotopic analysis of individual amino acids – a technique new to ecological studies – can be used to trace energy flow through animal communities in modern and ancient time periods. In particular, I focus on kelp forest food webs, which are nearshore …
Employing Earth Observations And Artificial Intelligence To Address Key Global Environmental Challenges In Service Of The Sdgs, 2019 Chapman University
Employing Earth Observations And Artificial Intelligence To Address Key Global Environmental Challenges In Service Of The Sdgs, Wenzhao Li
Computational and Data Sciences (PhD) Dissertations
Earth Observation (EO) data provides the capability to integrate data from multiple sources and helps to produce more relevant, frequent, and accurate information about complex processes. EO, empowered by methodologies from Artificial Intelligence (AI), supports various aspects of the UN’s Sustainable Development Goals (SDGs). This dissertation presents author’s major studies using EO to fill in knowledge gaps and develop methodologies and cloud-based applications in selected SDGs, including SDG 6 (Clean Water and Sanitation), SDG 11 (Sustainable Cities and Communities), SDG 14 (Life below Water) and SDG 15 (Life on Land). For SDG 6, the study focuses on spatiotemporal water recharge …
Growth Phase Proteomics Of The Heterotrophic Marine Bacterium Ruegeria Pomeroyi, 2019 Old Dominion University
Growth Phase Proteomics Of The Heterotrophic Marine Bacterium Ruegeria Pomeroyi, Dasha Krayushkina, Emma Timmins-Schiffman, Jessica Faux, Damon H. May, Michael Riffle, H. Rodger Harvey, Brook L. Nunn
OES Faculty Publications
The heterotrophic marine bacterium, Ruegeria pomeroyi, was experimentally cultured under environmentally realistic carbon conditions and with a tracer-level addition of 13C-labeled leucine to track bacterial protein biosynthesis through growth phases. A combination of methods allowed observation of real-time bacterial protein production to understand metabolic priorities through the different growth phases. Over 2000 proteins were identified in each experimental culture from exponential and stationary growth phases. Within two hours of the 13C-labeled leucine addition, R. pomeroyi significantly assimilated the newly encountered substrate into new proteins. This dataset provides a fundamental baseline for understanding growth phase differences in molecular …
An Investigation Of Metal Sulfides As The Source Of The Low Emissivity Anomaly On The Highlands Of Venus, 2019 University of Arkansas, Fayetteville
An Investigation Of Metal Sulfides As The Source Of The Low Emissivity Anomaly On The Highlands Of Venus, Sara Taeko Port
Graduate Theses and Dissertations
Since its detection in the 1960s the source of the unusual radar emissivity signal seen on several highlands on Venus has long eluded researchers. Researchers have determined that a mineral with a high dielectric constant could explain the signal. Using a Venus simulation chamber, we experimentally investigated this enigma to build upon the candidate mineral list that has been compiled over the last several decades. We tested the stability of 8 different minerals and elements at two to three different temperature/pressure regimes in three different gas mixtures meant to simulate the conditions found on Venus for a period of no …
Reconstructing Geographic And Trophic Histories Of Fish Using Bulk And Compound-Specific Stable Isotopes From Eye Lenses, 2019 University of South Florida
Reconstructing Geographic And Trophic Histories Of Fish Using Bulk And Compound-Specific Stable Isotopes From Eye Lenses, Amy A. Wallace
USF Tampa Graduate Theses and Dissertations
The present research examined the viability and utility of eye lenses as a source of lifetime stable-isotope records in fish. It is presented in three sections. The first section compared bulk isotopic variation (bulk analysis) within fish eye-lenses at two temporal resolutions and compared patterns obtained from left and right eyes. The first temporal resolution was lower in an attempt to expose broad-scale isotopic changes during life while reducing effort and cost. This approach did reveal lifetime patterns, but tended to miss certain life events, particularly during early life. The second resolution was higher and provided detail that was missed …