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Effect Of Sex On The Accumulation Of Hepatic Mercury In Mallards Wintering In Louisiana, Latorya E. Mason

Master's Theses

The increase in mercury production through anthropogenic activities has led to a global crisis of mercury pollution that poses a significant threat to the health of both humans and wildlife. Aquatic ecosystems are especially at risk due to the creation of methylmercury, a toxic form of mercury, by sulfate-reducing bacteria in anoxic sediments and soils. Methylmercury enters the food chain where it bioaccumulates in individual organisms and then biomagnified with increasing trophic level. Aquatic birds are useful bioindicators of many pollutants, including mercury, due to their abundance and position in the food chain. Previous studies have primarily focused on mercury …

Mercury Biomagnification In Aquatic Food Webs Of Great Smoky Mountains National Park, Zachary Winston Clark

Masters Theses

Mercury is a widespread pollutant threatening human, fish, and ecosystem health on a global scale. Biomagnification concentrates mercury in upper trophic level organisms including predatory fishes, a primary route of dietary mercury exposure for humans. However, mercury biomagnification is not well understood in stream ecosystems, especially in places with no known point sources of contamination. A 2016 study revealed that Smallmouth Bass Micropterus dolomeiu mercury concentrations varied between three streams in Great Smoky Mountains National Park (GSMNP), Tennessee USA. However, the reason for this spatial variation in mercury concentrations is not understood. Our objectives were to (1) measure environmental and …

The Impact Of The Use Of Mercury In Mining In Colombia, Johan Martinez

CMC Senior Theses

Artisanal and small-scale gold mining is a practice that is common all around the world, especially in Latin America, Africa, and Asia. It is also one of the leading consumers of mercury and leading sources of emissions. Governments have banned the use of mercury completely, including Colombia, but it continues to be used and emitted into the environment. This issue is exacerbated because there is a lack of standards, a lack of research done regarding mercury use in mining, and a complex socio-political history in Colombia. For this reason, this paper seeks to provide a proposed pathway for research to …

Addressing Mercury Contamination From Artisanal Gold Mining In Colombia: Pollution Exposure, Health Risk, And Educational Efforts In The Communities Of La Toma, Colombia, Kelli Mccourt

All Dissertations

Artisanal and small-scale gold mining (ASGM) has become a primary environmental and public health concern in the region of Colombia known as Alto Cauca. The predominantly Afro-descendent communities of Yolombó and La Toma in Alto Cauca have experienced pollution linked to the use of mercury in the ASGM process. For the past decade, mercury has emerged as a contaminant of increasing concern in the communities due to its toxicity and ability to bioaccumulate and biomagnify. Likewise, mining in the region raises concerns over the leaching of metals into local waters. Given the complexity of risk and pollution in the communities, …

Atmospheric Mercury At Storm Peak Laboratory: Development Of Methods To Calibrate Ambient Oxidized Mercury Measurements And Comparisons To A 3-D Photochemical Transport Model, Tyler Raymond Elgiar

All Graduate Theses and Dissertations, Fall 2023 to Present

Mercury (Hg) is a highly toxic metal found ubiquitously throughout the environment that has the potential to harm wildlife and human health. Human exposure to Hg can lead to symptoms such as blindness, loss of memory, ataxia, and death. Hg exposure to pregnant women and young children is of even greater concern, as high levels of Hg can hinder fetal and child development.

Hg is emitted into the atmosphere through natural and anthropogenic processes such as biomass burning and the incineration of coal, respectively. Hg exists in the atmosphere as elemental Hg (Hg⁰) or in an oxidized form …

Preliminary Assessment For Critical Minerals In The Terlingua Quicksilver District, Texas And Tres Marias Mine, Chihuahua, Mexico, Eduardo Lee Zuniga

Open Access Theses & Dissertations

The Terlingua Quicksilver district was discovered around the 1880s and was a mercury producing district from 1900 through 1946. The most productive years were during World War one and two. From 1900-1946 the Terlingua Quicksilver District (TQD) produced 150,000 flasks; 80% came from three mines: the Rainbow-Chisos, Mariposa, and Study Butte mines. The structural controls of the Mercury mineralization within these mines are breccia pipes and fractures, often located near igneous intrusions. This study will assess the potential for Critical Minerals and Rare Earth Elements in the Terlingua Quicksilver District. Fifty-five samples have been collected and analyzed for forty-four different …

Large-Scale Volcanism On The Terrestrial Planets, Keenan Ben Golder

Doctoral Dissertations

Evidence for mafic volcanism has been found on each planet in the inner Solar System. Lava flows on these planets range in size from 10s to 1000s of kilometers in extent. I investigated large-scale lava flows on Mercury, Earth, and Mars throughout the chapters in this dissertation. Each of these lava flows provides an avenue to study the emplacement and evolution of lava on various planets and under differing conditions, the factors that affect their overall extent, and potential source areas.

Chapter One investigates large-scale lava flows in the Cerberus region on Mars, specifically to understand their emplacement history, material …

Tacitus, Barditus, And Odin's Eleventh Spell, Marie Skinner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Roman Historian Cornelius Tacitus wrote about native Europeans in 98 C.E., around a thousand years before the same peoples began recording their own history. Despite this, the work titled Germania is little-known and under-utilized. It is only by studying Germania and discussing it that the text will be seen for what it is and neither dismissed nor taken out of context. This thesis examines a few of the many passages of Germania that correspond with archaeological, literary, legal, and artistic information from later periods, demonstrating the value of Tacitus’ work to anyone studying European history.

Understanding The Spatial Distribution Of Mercury- Contaminated Sediment Along The Androscoggin River, Debbie F. Sulca

Dartmouth College Master’s Theses

Mercury (Hg) from a former Chlor-Alkali Facility (active from the late 1890s until the 1960s) continues to leach into the Androscoggin River from glacial till and bedrock, contaminating the downstream floodplain. Previous work has shown that downstream gradients in stream power affect the erosion and deposition of the floodplain. This study sought to determine if the spatial distribution of Hg downstream of the point source can be predicted from gradients in stream power along a 5 km reach starting 4 km downstream from the point source. Floodplain soil samples were collected at five transects, across three flood recurrence intervals (2-, …

Rapid Scoping Review Of The Epidemiological Evidence For Mercury Exposure And Prevalence Of Alzheimer’S Disease, Rebecca Mattingly

Theses and Dissertations--Public Health (M.P.H. & Dr.P.H.)

This rapid scoping review examines the current body of epidemiologic research evaluating the potential linkage between environmental exposure to mercury and Alzheimer's disease (AD). Alzheimer’s disease accounts for 60-80% of all neurodegenerative disease in the United States and was the seventh leading cause of death in Kentucky in 2020. The exact etiology of AD needs further investigation; however, environmental factors such as pesticides, arsenic, cadmium, lead, and mercury have been correlated with development of AD lesions, cognitive decline, and AD. Mercury is a toxic metal that can be found in air, water, and soil, both from natural and human-made sources. …

Bioaccumulation Of Polychlorinated Biphenyl Compounds And Mercury In A Mining Impacted Aquatic Ecosystem, Michelle Bollini

Dissertations, Master's Theses and Master's Reports

The Keweenaw area continues to be influenced by the century of copper mining that ended nearly 50 years ago. This project is focused on Torch Lake, an aquatic ecosystem that has been heavily impacted by mining waste disposal. The watershed has been impaired by mine discharge and tailings, smelter and smokestack plumes, and poor waste disposal practices. The lake is listed as a Great Lakes Area of Concern with beneficial use impairments of restrictions on fish consumption and a degraded benthic community. Polychlorinated biphenyl compounds (PCBs) and methylmercury (MeHg) are persistent, bioaccumulative, and toxic substances (PBTs). These contaminants pose threats …

Relationships Between Mercury And Trophic Level In Nine Coastal Pelagic Fishes Off Southeastern Florida, Emily Akins

All HCAS Student Capstones, Theses, and Dissertations

State and federal agencies have issued consumption advisories for various fish species for many years, including in Florida. Upper-level predatory fish, such as tunas and mackerels, are especially popular with anglers but are susceptible to high levels of mercury through bioaccumulation and biomagnification. This study used two data sets over two time periods, 2010-2012 and 2020-2021, to compare mercury and trophic level relationships in nine coastal pelagic fishes is Southeastern Florida. As these species are popular in recreational fisheries, charter and tournament catches formed the base of the samples that were analyzed for total mercury along with carbon and nitrogen …

Heavy Metal Distribution Across Three Georgia Estuaries Using Coastal Sharks As Sentinel Species, Allyson Stiles

Master of Science in Integrative Biology Theses

Estuaries are transitional environments that play key roles in coastal ecosystem functioning by providing essential habitats to ecologically important plant and animal species. Estuaries are exposed to a number of anthropogenic impacts, including heavy metal contamination from human activities. However, few studies have examined heavy metal distribution within Georgia’s estuaries and how intact salt marsh ecosystems could play a role in filtering and sequestering contaminants, such as Mercury (Hg). This thesis examined blood total mercury (THg) concentrations of four coastal shark species and concentrations of five heavy metals (Hg, As, Cr, Cu, and Pb) within the water and sediments of …

Predicting Contaminant Transfer Following Re-Established Connectivity In The Boardman River, Ross A. Gay

All NMU Master's Theses

Anthropogenic alteration of the environment began as soon as people settled the Great Lakes (GL) region with hydrologic alteration (dams) and discharges of man-made chemicals into the air and water as populations and industry expanded. Consequently, the GL became a reservoir of anthropogenic contaminants such as mercury (Hg), polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichloroethylene (DDT), and organochloride compounds. Migratory fish accumulate and magnify contaminants within their tissues and transport them across ecosystem boundaries. Re-established connectivity in the form of dam removal has the potential to allow contaminant laden migrants access to ecosystems previously inaccessible. Here I assess the contaminant burden of a …

Investigating The Mechanisms Driving Mercury Reduction And Emissions In Soil, Hamil Patel

Student Theses

The water-induced emission of mercury from soil has been studied, but a complete understanding of the mechanisms driving mercury reduction and emission in soil has not been reached. The current understanding is an immediate expulsion of soil gaseous mercury upon water treatment and an upward transport of dissolved soil ionic mercury as the water evaporates. We analyzed emissions from several types of samples using various methods to further our understanding on the mechanisms involved. Light-induced emissions from aqueous samples of humic acid (HA) spiked with mercury (II) chloride (HgCl₂) showed that at higher concentrations of HA, less mercury …

Cysteine Metallochemistry And Metal Binding: Quantification Of The Thermodynamic Foundations Of Cellular Homeostasis, Matthew R. Mehlenbacher

Dartmouth College Ph.D Dissertations

Metals are required for life. Many metalloproteins contain cysteine in their metal-binding site (MBS) and cysteines are unique in that they are reactive, and strongly bind certain metals, which aid in metal selectivity and specificity. Using isothermal titration calorimetry (ITC), the thermodynamic foundation for metal binding, cellular protection, and transcriptional regulation, which all utilize cysteines in their MBS, are quantified.

In bacteria there are metalloprotein pathways that actively uptake mercury, which are regulated by the metalloregulatory protein MerR. MerR de-represses the transcription of these mer proteins in a metal-dependent manner. Using ITC, the thermodynamic foundation of the negative allosteric coupling …

Detection, Occupancy, Abundance, And Mercury Accumulation Of The Alligator Snapping Turtle (Macrochelys Temminckii) In Texas, David Rosenbaum

Electronic Theses and Dissertations

Land use practices and physical alterations of ecosystems result in habitat loss and fragmentation, while chemical alterations, such as pollutant input, reduce habitat quality and health of exposed organisms. Here, I investigated the effects of watershed- and local-scale environmental variables on the occupancy, abundance, and mercury accumulation of a threatened aquatic species (Macrochelys temminckii, i.e., alligator snapping turtle) within the southwestern periphery of its distribution. Hierarchical modeling suggested the distribution of the species is more affected by watershed-scale land-cover than local habitat, and provided a baseline estimate of average species abundance across its range in eastern Texas. Abundance …

Compound, Elemental, And Isotopic Perspectives On Mercury Mobilization During Thaw In A Discontinuous Permafrost Zone, Maria F. Fahnestock

Doctoral Dissertations

Arctic ecosystems are a major global sink for both carbon (C) and mercury (Hg), both of which are influenced by anthropogenic activities. The accelerated climate-change-induced warming documented in the Arctic has led to permafrost thaw resulting in landscape evolution from hydrological, vegetation and microbial shifts. All of these resulting changes have the potential to influence how Hg, a toxic contaminant, is mobilized and re-cycled in this ecosystem. In this body of work, I investigate patterns of Hg speciation, elemental abundances, and stable isotopes across the thaw gradient in a permafrost peatland and interconnected freshwater lakes in Abisko, Sweden to assess …

Mercury Concentrations And Mercury Methylation Along The Freshwater To Marine Continuum, Lindsay D. Starr

Browse all Theses and Dissertations

Mercury (Hg) is a neurotoxin that can have detrimental impacts on the human nervous system and on brain development in infants. Methylmercury (MeHg) is the most toxic form of Hg and can concentrate to potentially harmful levels in higher levels of marine food webs. Production of MeHg in oxic water columns is poorly understood due to lack of knowledge of the mechanisms of formation and distribution. Recent work has reported widespread, putative Hg methylation genes in nitrite oxidizers, but any relationship with nitrifiers is unknown. This work focuses on Hg water column distribution, speciation, and methylation. The aims of this …

Avian Haemosporidian Blood Parasite Diversity, Prevalence, And Distribution In Michigan’S Western Upper Peninsula, Maria M. Ferrer

Dissertations, Master's Theses and Master's Reports

Avian haemosporidian parasites, known as avian malaria (phylum Apicomplexa) can diminish an individual bird’s fitness by causing parasitemia, anemia, and reduced survival. Climate change is predicted to increase the spread of malarial parasites into more northerly latitudes where little is known about community compositions of these parasites. I assessed the prevalence and diversity of haemosporidian parasites in the first-ever community-level sampling of malaria in songbirds across the western Upper Peninsula of Michigan. In total, 179 blood samples were collected from birds representing 17 species, at five locations in the Upper Peninsula, including a mature forest, an early successional forest, and …

Using Sedimentary Mercury Geochemistry To Evaluate The Niagara-Salina Transition, Silurian Michigan Basin, Usa, Sara Hayes

Masters Theses

The Niagara-Salina boundary in the Michigan Basin is marked by an abrupt transition from carbonates to evaporites. Though the cause is uncertain, previous work suggests the onset of Salina evaporites was driven by basin restriction, but the presence of several global carbon isotope excursions (CIE) suggest a global driver. This study builds on this discussion using two relatively new geochemical proxies - elemental mercury concentrations [Hg] and Hg isotopes.

Mercury concentrations [Hg] were measured in 88 samples from the State Kalkaska #2-15 core from 6604.03 ft to 6797.42 ft. [Hg] ranges from 0.11 to 0.62 mg/kg and [Hg]/TOC from 0.038 …

U.S. Cosmetic Policy Reform: A Growing Need To Protect Communities Of Color From Exposure To Toxic Chemicals, Amna Haslam

Master's Projects and Capstones

Women of color are at a higher risk of exposure to toxic chemicals because of their use of more personal care products when compared to white women. A literature review was conducted focusing on mercury, a highly toxic heavy metal, found in some skin lightening creams used in Latinx, Black, and Southeast Asian communities to evaluate the impact of toxic chemicals used in communities of color. The use of skin lightening products is associated with the perception of beauty and social advantage. Further, women of color regardless of educational attainment experience the same social pressures to lighten their skin. This …

Planetary Processes Active And Ancient: Hollowing On Mercury, Ancient Crust Formation On Mars, And Identifying Mars-Analog Habitats., Michael Steven Phillips

Doctoral Dissertations

This dissertation comprises a thermophysical model that shows elemental sulfur may be involved in the potentially active processes that form enigmatic features called hollows on the Mercurian surface, a suite of remote sensing techniques that unveil anorthositic rocks in ancient martian crust, and deep learning to discover the spatial resolutions necessary to identify astrobiology targets in images of Mars analog landscapes.

On Mercury, hollows are high-reflectance, flat-floored depressions observed nearly globally. Hollows are thought to form via sublimation, or a “sublimation-like” process, but the identity of the sublimating phase is poorly constrained. To better understand which phase might be responsible …

Terrestrial Laser Scanning Technology For Measuring Streambank Retreat Along East Fork Poplar Creek And Calculating The Effect On Mercury Release., José L. Martínez Collado

Masters Theses

Mercury (Hg) is a globally distributed inorganic pollutants of human concern. The high toxicity is mainly related to the capacity of Hg species to accumulate and biomagnify along aquatic food webs. Along East Fork Poplar Creek (EFPC), erosion represents the principal mercury input into the local waters, eventually reaching humans through the food chain. This research project aimed to monitor streambank erosion along a mercury-contaminated creek using Light Detention and Ranging (Lidar) technology and erosion pins. A Terrestrial Laser Scanner (TLS) was used to generate high-resolution point clouds from August 2020 to January 2021 across nine streambank locations to detect …

Association Between Stream Impairment By Mercury And Superfund Sites In The Conterminous Usa, Karessa L. Manning

Masters Theses

Mercury is a natural element that can cause harm to the brain, heart, kidneys, lungs, and immune system, especially to fetuses developing in the womb. Many natural and anthropogenic factors contribute to mercury in the environment, such as geologic deposits, landfills, gold and silver mining operations, cement production, and atmospheric deposition. Mercury has been identified as a contaminant of concern at many National Priority List (NPL) sites, however, studies on contamination at NPL sites are often only conducted on a local level. This study was to analyze the potential connection between mercury-contaminated NPL sites and the presence of mercury impaired …

Characterising Recent Terrestial Influence On Coastal Antarctic Air Masses Using Radon-222 And Physiochemical Properties, Daniel Saeed

Science, Medicine & Health - Honours Theses

Antarctica exhibits near pristine conditions to study natural chemical processes that occur under extreme temperatures and radiation conditions. As such, Antarctica provides an ideal location to observe the long-term hemispheric-scale trends in atmospheric trace gases. Air mass observations at three coastal Antarctic stations (Casey, Davis, and Mawson) during 2018/19 resupply voyages aboard the RV Aurora Australis were classified according to their recent fetch history, and their degree of terrestrial influence characterised via radon-222 (radon) observations. Fetch classification categories were based on absolute water content, with oceanic being the wettest and katabatic being the driest (i.e., originating from the Antarctic interior). …

Application Of Passive Air Samplers For Atmospheric Research, And Determination Of Metals In Tree Rings And Marine Sapropel By Icp-Ms, Byunggwon Jeon

Electronic Theses and Dissertations

This research focuses on studies of atmospheric mercury (Hg) using passive air samplers (PAS) and studies of trace elements in tree cores and sediment using inductively coupled plasma mass spectrometry (ICP-MS). Mercury is a toxic element that is dispersed globally through the atmosphere. Accurately measuring airborne Hg concentrations aids understanding of the pollutant’s sources, distribution, cycling, and trends. Mercury PAS are designed to capture gaseous elemental mercury (GEM) at a known rate. Compared to active air sampling the low-cost of PAS allows for greater spatial coverage. We used a commercially available Hg PAS (MerPAS®) and observed differences in GEM between …

Enhancing Plasmonic Nanomaterials: Colorimetric Sensing And Sers, John Crockett

WWU Graduate School Collection

Nanomaterials, materials with at least one dimension on the nanoscale have become an area of extreme scientific interest due to their many unique properties with applications in catalysis, optics, and sensing, just to name a few. Metal nanoparticles are particularly interesting because of the interactions between light and surface electrons in the metal’s conduction band, called localized surface plasmons. In anisotropic metal nanoparticles these plasmons are especially exciting due to the highly responsive quality of the plasmonic resonance associated with their varied nano dimensions. Gold nanorods and nano dendrites in particular exhibit electromagnetic effects which are specifically associated to the …

Metagenomic Identification And Classification Of The Mercury-Methylating Gene Hgca In Response To Water Table And Plant Functional Group Manipulations In Peat Soil, Madeline Peterson

Dissertations, Master's Theses and Master's Reports

Methyl-mercury (MeHg) is a potent neurotoxin that threatens the health of humans and wildlife alike. Climate warming threatens to shift regional precipitation and climate regimes in peatland environments, which could destabilize northern peatlands and accelerate both Hg release from soil and MeHg production. Peatlands are among the leading hotspots for MeHg, yet little is known about the community composition or functional relationship of mercury-methylating microbes in response to varying environmental conditions. The recognized mercury-methylating genes responsible for this activity are the obligatory gene pair hgcA and hgcB. Metagenomic data from the full-factorial peatland mesocosm experiment PEATcosm was obtained to …

Improving Our Understanding Of Atmospheric Mercury And Bromine Over The Southern Ocean And Antarctic Sea-Ice Region, Neil Page

University of Wollongong Thesis Collection 2017+

Of the reactive halogens, those containing reactive bromine are of particular scientific interest as they play a key role in the chemistry and oxidising capacity of the polar troposphere (Simpson et al., 2015). In early spring, bromine molecules (as Br2) are rapidly released from the sea ice via heterogenous reactions on sea salt surfaces, both in the sea ice itself and on blowing snow (Simpson et al., 2015; Huang et al., 2018; Peterson et al., 2019). This rapid bromine release can initiate a chemical reaction, known as a bromine explosion, which oxidises gaseous elemental mercury, resulting in the subsequent deposition …