Environmental Chemistry Commons^™

Observations Of Greenhouse Gas Isotopologues With Ace-Fts And Waccm, Eric Michael Buzan

Chemistry & Biochemistry Theses & Dissertations

Increases in greenhouse gas concentrations in the atmosphere are the major driver of climate change. Quantifying the sources and sinks of these gases is a major focus of research. Measuring isotopologues, or molecules that differ in isotopic composition, is one useful way of constraining the budget of a molecule as they are highly sensitive to different sources and sinks. However, measurements above the surface have been restricted to a few locations and have only reached the lower stratosphere. Satellite-based remote sensing can achieve nearly global measurement coverage, but so far no satellites have measured isotopologues.

Presented here are measurements of …

Comprehensive Silica Removal With Ferric Compounds For Industrial Wastewater Reuse, Ehren D. Baca

Civil Engineering ETDs

Cooling towers, integrated circuit (IC) manufacture and reverse osmosis (RO) generate copious amounts of wastewater high in colloidal and reactive silica inhibiting on-site or synergistic reuse. Silica present in cooling water can reach solubility limits via evaporation and form impervious scale on heat transfer surfaces that decreases efficiency. When water is treated by RO operating at high rejection, silica forms difficult-to-remove scale on the membrane feed side in the form of glassy patches and communities of aggregate particles, inhibiting aspirations for zero liquid discharge. Current methods for silica scale mitigation include abundant dosing with chemical antiscalents or complex operating schemes. …

Depletion Of Ozone And Reservoir Species Of Chlorine And Nitrogen Oxide In The Lower Antarctic Polar Vortex Measured From Aircraft, T. Jurkat, C. Voigt, S. Kaufmann, J.-U. Grooß, H. Ziereis, A. Dörnbrack, P. Hoor, H. Bozem, A. Engel, H. Bönisch, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Novel airborne in situ measurements of inorganic chlorine, nitrogen oxide species, and ozone were performed inside the lower Antarctic polar vortex and at its edge in September 2012. We focus on one flight during the Transport and Composition of the LMS/Earth System Model Validation (TACTS/ESMVal) campaign with the German research aircraft HALO (High-Altitude LOng range research aircraft), reaching latitudes of 65°S and potential temperatures up to 405 K. Using the early winter correlations of reactive trace gases with N₂O from the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS), we find high depletion of chlorine reservoir gases up to ∼40% …

Evaluation Of A Filtration Sorbent For Remediation Of Arsenic In Groundwater, Clement Do

Electronic Theses, Projects, and Dissertations

A commercially available product, PURA PhosLock, was identified and evaluated for use as a sorbent to remove dissolved arsenic (As) from drinking water. Although marketed as a product to remove phosphate in aquaria, it is composed of iron oxide hydroxide (i.e., FeO(OH)), which is also known to adsorb dissolved As species from water. Arsenic was measured using standard methods and Graphite Furnace Atomic Absorption Spectroscopy. A first rough filtration test was performed to see if the PhosLock adsorbed As well. About 50 g of PhosLock was used to filter 10 L of tap water containing 100 ppb As. No detectable …

Caffeine And Acetaminophen Concentration And Other Water Quality Parameters Along The Middle To Lower Bear River, Autumn Slade

Undergraduate Honors Capstone Projects

Various water quality parameters were measured at seven sites along the Middle to Lower Bear River and compared across the sites, to past data and to set standards in Utah and Idaho. Much of the data was comparable to past data with most state standards being met. However, nitrate was above indicator level for half of the sites, and turbidity is a problem at the last two sites. Also, chloride and unionized ammonia are at high levels by the last site. Overall, the river tended to decrease in water quality as it moved downstream, with dams like at Cutler Reservoir …

Homogeneous Ligand-Centered Hydrogen Evolution And Hydrogen Oxidation : Exploiting Redox Non-Innocence To Drive Catalysis., Andrew Z. Haddad

Electronic Theses and Dissertations

Hydrogen is a promising carbon-free fuel / energy carrier and is an essential building block for many industrial and agricultural processes. Rising energy demands have ignited interest in the development of carbon-free and carbon neutral energy sources. In this context, hydrogen is an attractive candidate—being energy-dense, carbon-free—and easily accessible through a two-electron reduction of water. Accordingly, many electrochemical homogeneous catalyst systems have been studied, with a focus on understanding the mechanism of hydrogen evolution proceeding through metal-hydride intermediates. However, there has been a renaissance in hydrogen evolution reaction (HER) catalyst design, with many groups implicating ligand redox non-innocence as a …

Role Of Atp Hydrolysis And Mechanism Of Substrate Reduction In Nitrogenase, Sudipta Shaw

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nitrogen is essential for life on earth as it is a major constituent of amino acids and nucleic acids. Nitrogen gas (N₂) is the most abundant form of nitrogen in the atmosphere but the strong N≡N bond makes it unavailable for most organisms. Certain prokaryotes known as diazotrophs possess the unique ability to convert N₂ to ammonia (NH₃) which can be utilized by other organisms as a source of nitrogen. The diazotrophs perform this difficult reaction with the help of a complex metalloenzyme, nitrogenase. This enzyme is a major contributor of the fixed source of …

Channel Bar Morphology, Distribution, And Mining-Related Geochemistry In The Big River, St. Francois County, Missouri: Implications For Geomorphic Recovery, Lindsay Marie Olson

Graduate Theses/Dissertations

Tailings releases associated with large-scale historical Pb mining in St. Francois County, Missouri resulted in system-wide contamination of Pb and excess sediment in the Big River. Previous studies have addressed basin and segment scale variability of the contaminants; however, little is known about reach and bar scale variability. This study addresses how mining sediment inputs influence bar form and geochemistry across a range of scales. Bar sediment samples were collected at 21 reaches and analyzed for particle size and geochemistry, while air photo analysis was used to evaluate channel morphology, bar type, and area. Bar area is initially low in …

Functionalized Silica Gel For Adsorption Of Cesium From Solution, Kenneth Marshall Seaton Iii

Electronic Theses and Dissertations

Mesoporous silica gel containing embedded phosphotungstic acid (PTA) was synthesized by sol-gel co-condensation of tetraethyl orthosilicate with PTA in acidic media. The obtained material had high Brunauer-Emmett-Teller Theory (BET) surface area and pore volume. A characteristic band of the Keggin structure of PTA was present in its FT-IR spectrum while its X-ray diffraction patterns were absent. This proved the embedding of PTA on a sub-molecular level and not as a second phase. Acidic sites were determined by neutralization with base in aprotic solvent, followed by titration of the remaining base with an acid. The material demonstrated high adsorption capacity of …

Phosphomolybdic Acid Catalysis Of Cellulose Hydrolysis, Troy R. Dolmetsch

Undergraduate Honors Theses

Renewable sources such as cellulose derived biofuels are sought after in order to replace fossil fuel sources that are currently used to meet energy demands. Cellulose is a biological polymer composed of a chain of glucose molecules. Hydrolysis of cellulosic materials then has potential to serve as a source of renewable energy in the form of biofuels. The crystalline structure of cellulose is very stable, and current methods of catalyzed hydrolysis are inefficient for industrial application. This project explores the use of phosphomolybdic acid (PMA) in water to catalyze hydrolysis of microcrystalline cellulose. Temperature of hydrolysis was varied from 40 …

Influence Of Histidine Residues, Ph And Charge Interactions On Membrane-Spanning Peptides, Ashley N. Henderson

Graduate Theses and Dissertations

Designed transmembrane peptides were employed for investigations of histidine residues within the hydrophobic environment of the lipid bilayer by means of oriented solid-state deuterium NMR spectroscopy. Using the model peptide GWALP23 sequence (GGALW(LA)6LWLAGA) as a host framework, the effects of single and double histidine mutations were explored. Replacement of leucine residue 12 to polar neutral histidine had little influence on the peptide average orientation, however under strongly acidic pH conditions in DOPC bilayers, the histidine becomes positively charged (pKa 2.5) and the GWALP23-H12 peptide exits the membrane and adopts a surface-bound orientation. Conversely, mutation of leucine 14 to neutral histidine …

Oxidation Of Substituted Catechols At The Air-Water Interface: Production Of Carboxylic Acids, Quinones, And Polyphenols, Elizabeth A. Pillar, Marcelo I. Guzman

Chemistry Faculty Publications

Anthropogenic activities contribute benzene, toluene, and anisole to the environment, which in the atmosphere are converted into the respective phenols, cresols, and methoxyphenols by fast gas-phase reaction with hydroxyl radicals (HO(•)). Further processing of the latter species by HO(•) decreases their vapor pressure as a second hydroxyl group is incorporated to accelerate their oxidative aging at interfaces and in aqueous particles. This work shows how catechol, pyrogallol, 3-methylcatechol, 4-methylcatechol, and 3-methoxycatechol (all proxies for oxygenated aromatics derived from benzene, toluene, and anisole) react at the air-water interface with increasing O3(g) during τc ≈ 1 μs contact time and contrasts their …

Annual Variation In Event-Scale Precipitation Δ 2 H At Barrow, Ak, Reflects Vapor Source Region, Annie Putman, Xiahong Feng, Leslie Sonder, Eric Posmentier

Dartmouth Scholarship

In this study, precipitation isotopic variations at Barrow, AK, USA, are linked to conditions at the moisture source region, along the transport path, and at the precipita- tion site. Seventy precipitation events between January 2009 and March 2013 were analyzed for δ2H and deuterium ex- cess. For each precipitation event, vapor source regions were identified with the hybrid single-particle Lagrangian inte- grated trajectory (HYSPLIT) air parcel tracking program in back-cast mode. The results show that the vapor source re- gion migrated annually, with the most distal (proximal) and southerly (northerly) vapor source regions occurring during the winter (summer). This may …

Spectrofluorometric Analysis Of Bisphenol-A In Drinking Water Bottles, Jeff Brochetti

Student Scholar Showcase

Spectrofluorometric Analysis of Bisphenol-A in Drinking Water Bottles

Bisphenol-A (BPA) is of environmental concern due to its ability to act as an endocrine disruptor in humans and many other animals. In the food industry, BPA is widely used in the production of plastic bottles and plastic liners in aluminum cans. Over time, trace amounts of BPA can leach from the container and into the contents inside. A new method of testing for trace amount of BPA involved the formation of an inclusion complex with ß-Cyclodextrin. With the formation of the inclusion complex, it becomes much easier to analyze low concentrations …

Catalyzed Synthesis Of Zinc Clays By Prebiotic Central Metabolites, Marcelo I. Guzman, Ruixin Zhou, Kaustuv Basu, Hyman Hartman, Christopher J. Matocha, S. Kelly Sears, Hajatollah Vali

Chemistry Faculty Publications

How primordial metabolic networks such as the reverse tricarboxylic acid (rTCA) cycle and clay mineral catalysts coevolved remains a mystery in the puzzle to understand the origin of life. While prebiotic reactions from the rTCA cycle were accomplished via photochemistry on semiconductor minerals, the synthesis of clays was demonstrated at low temperature and ambient pressure catalyzed by oxalate. Herein, the crystallization of clay minerals is catalyzed by succinate, an example of a photoproduced intermediate from central metabolism. The experiments connect the synthesis of sauconite, a model for clay minerals, to prebiotic photochemistry. We report the temperature, pH, and concentration dependence …

Detection And Quantitation Of Tetracycline Antibiotics In Agricultural Swine Wastes, Ali Jamal Abdulrheem

Masters Theses & Specialist Projects

The spread of tetracyclines through agricultural systems is causing the present bacteria to develop antibiotic resistance. The spread of this bacteria, as well as the tetracycline antibiotics in the environment is dangerous because these antibiotics pose health hazards for humans. The overuse of antibiotics, which are added to livestock feed, results in the antibiotics being released into the environment via animal feces. In this research, we have attempted to design an analytical method to isolate antibiotics from agricultural wastes with subsequent detection using liquid chromatography and mass spectrometry (LC-MS). The antibiotics investigated in this study were tetracycline, chlortetracycline, and oxytetracycline. …

Polychlorinated Biphenyls, Polybrominated Biphenyls, Polychlorinated Dibenzo-P-Dioxins And Polychlorinated Dibenzofurans, Prasada Rao S. Kodavanti, Joseph Valdez, Jae-Ho Yang, Margarita Curras Collazo, Bommanna G. Loganathan

Faculty & Staff Research and Creative Activity

Environmental contamination levels, human exposure, toxicokinetics, and health effects of PCBs, PBBs, PCDDs/PCDFs are discussed.

Multi-Scaled Approaches For Protecting Montana's Watersheds And Water Resources, Elizabeth Yoder

Graduate Student Portfolios, Professional Papers, and Capstone Projects

The central theme carried among my four portfolio pieces is: using scientific and governmental approaches to conserve watershed health. For the purposes of this portfolio, I define watershed health as a very general term that describes the state of water quantity and quality that is available for human and ecosystem needs in a watershed. I see each of my portfolio pieces focusing on a different scale and method (i.e., science or government, including different levels of government, local, state and federal) for conserving watershed health. My first portfolio piece reviews water quality degradation caused by pharmaceuticals and personal care products …

Reactivity Of Ketyl And Acetyl Radicals From Direct Solar Actinic Photolysis Of Aqueous Pyruvic Acid, Alexis J. Eugene, Marcelo I. Guzman

Chemistry Faculty Publications

The variable composition of secondary organic aerosols (SOA) contributes to the large uncertainty for predicting radiative forcing. A better understanding of the reaction mechanisms leading to aerosol formation such as for the photochemical reaction of aqueous pyruvic acid (PA) at λ ≥ 305 nm can contribute to constrain these uncertainties. Herein, the photochemistry of aqueous PA (5-300 mM) continuously sparged with air is re-examined in the laboratory under comparable irradiance at 38° N at noon on a summer day. Several analytical methods are employed to monitor the time series of the reaction, including (1) the derivatization of carbonyl (C═O) functional …

Topological And Thermodynamic Factors That Influence The Evolution Of Small Networks Of Catalytic Rna Species, Jessica Anne Mellor Yeates, Philippe Nghe, Niles Lehman

Chemistry Faculty Publications and Presentations

An RNA-directed recombination reaction can result in a network of interacting RNA species. It is now becoming increasingly apparent that such networks could have been an important feature of the RNA world during the nascent evolution of life on the Earth. However, the means by which such small RNA networks assimilate other available genotypes in the environment to grow and evolve into the more complex networks that are thought to have existed in the prebiotic milieu are not known. Here, we used the ability of fragments of the Azoarcus group I intron ribozyme to covalently self-assemble via genotype-selfish and genotype-cooperative …