Theses and Dissertations at Montana State University (MSU)
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Item Impact: how ecotourism is harming our wild spaces(Montana State University - Bozeman, College of Arts & Architecture, 2023) Fajack, Zachary Blake; Chairperson, Graduate Committee: Dennis AigThe following thesis looks at how the U.S. National Parks Service has balanced (or at least attempted to balance) two competing goals: to preserve America's wild spaces and make those wild spaces accessible to the public. The thesis explains how the parks came to find themselves in this balancing act and how they have managed to tackle the conflict in the past. The main argument of the thesis is that much of this conflict appeared as the result of the park's implementation of transportation infrastructure. To effectively support this argument, the project broadly goes over how roadways took over much of the transportation infrastructure in the parks and how they negatively impact the environment. The thesis then discusses how the National Parks Service may more effectively combat those impacts. The remainder of the paper dedicates itself to constructing a travel film that effectively communicates the problems and solutions found and details of the film's production. The thesis found that travel films are uniquely suited to this goal and how their utilization may serve as a powerful advocacy device.Item Optimizing site-specific nitrogen fertilizer management based on maximized profit and minimized pollution(Montana State University - Bozeman, College of Agriculture, 2022) Hegedus, Paul Briggs; Chairperson, Graduate Committee: Bruce D. Maxwell and Stephanie A. Ewing (co-chair); This is a manuscript style paper that includes co-authored chapters.Application of nitrogen fertilizers beyond crop needs contributes to nitrate pollution and soil acidification. Excess nitrogen applications are most prevalent when synthetic fertilizers are applied at uniform rates across fields. Precision agroecology harnesses the tools and technology of variable rate precision agriculture, a common but underutilized management strategy, to make ecologically conscious decisions about field management that promote economic and environmental sustainability. On-farm precision experimentation provides the basis for making data driven ecological management decisions through the field-specific assessment of crop responses. This dissertation work used on-farm experimentation with variable nitrogen fertilizer rates, combined with intensive data collection and data science, to address the main objective of this dissertation: development and evaluation of optimized nitrogen fertilizer management on a subfield scale, based on maximization of farmer net-returns and nitrogen use efficiency. The response of winter wheat yield and grain protein concentration to rates of nitrogen fertilizer application varied among fields, and across time, which influenced the model form used to characterize the relationships of grain yield and quality to fertilizer within a field. Machine learning approaches, such as random forest regression, tended to provide the lowest degree of error when forecasting future crop responses. Machine learning also demonstrated its utility for use in agronomic applications, as a support vector regression model provided the most accurate predictions of nitrogen use efficiency on a subfield scale. Crop response and nitrogen use efficiency models were integrated into a decision-making framework for optimized site-specific based nitrogen fertilizer management based on between maximized profits and minimized potential of nitrogen loss. Simulations of optimized site-specific nitrogen fertilizer management compared to farmer's status quo management showed a 100% probability across all fields tested that that mean net-return from the site-specific approaches were more profitable than applications of farmer selected nitrogen fertilizer rates. However, even while considering minimization of the potential for nitrogen loss when identifying optimum nitrogen fertilizer rates, there was field specific variation in the probability that site-specific, compared to farmer selected, nitrogen fertilizer management reduced the total amount of nitrogen applied across a field.Item Biochemical and biophysical characterization of plastic degrading aromatic polyesterases(Montana State University - Bozeman, College of Letters & Science, 2019) Topuzlu, Ece; Chairperson, Graduate Committee: Valerie Copie; Brandon C. Knott and Mark D. Allen were authors and Japheth Gado, Harry P. Austin, Erika Erickson, Bryon S. Donohoe, Nicholas A. Rorrer, Fiona L. Kearns, Graham Dominick, Christopher W. Johnson, Valerie Copie, Christina M. Payne, H. Lee Woodcock, Gregg T. Beckham and John E. McGeehan were co-authors of the article, 'Structural and biochemical characterization of MHETASE' submitted to the journal 'Proceedings of the National Academy of Sciences of the United States of America' which is contained within this dissertation.As the world is producing more plastics than it can recycle, accumulation of manmade polymers in the environment is becoming one of the greatest global threats humanity is facing today. One of the major contributors to the plastics pollution problem is polyethylene terephthalate (PET), an aromatic polyester widely used in the packaging, beverage, garment and carpeting industries. As a response to the onslaught of plastics in the environment, fungi and bacteria are evolving metabolic pathways to convert plastics into useable energy sources. One of these organisms, a bacterium, Ideonella sakaiensis 201-F6, has recently been identified to convert PET into its monomers, terephthalic acid (TPA) and ethylene glycol (EG), and to use these compounds for energy and growth. I. sakaiensis' ability to convert PET is made possible by two enzymes, named PETase and MHETase. As a first step, PETase breaks down the insoluble substrate PET into a soluble major hydrolysis product - mono-(2- hydroxyethyl) terephthalate (MHET), which is then further hydrolyzed by MHETase into TPA and EG. Crystal structure of PETase, as well as some of its biochemical features, have been reported several times to date, but MHETase has remained largely uncharacterized. This work focuses on further discovery-driven biophysical and biochemical characterization of PETase, visualization of PETase activity on various polyester surfaces, as well as the structural and biochemical characterizations of the MHETase enzyme. We have found that several aspects of PETase-mediated substrate surface modification hydrolysis mechanisms differ depending on the specific mechanical and material characteristics of the substrate. We have also found that PETase is inhibited by BHET. Additionally, we have solved the crystal structure of MHETase. MHETase consists of an alpha/beta hydrolase domain, and a 'lid' domain, commonly seen in lipases. Molecular dynamics simulations revealed the mechanism of MHETase action. Through bioinformatics approaches, we have also identified mutants of interest for improved MHETase activity. Coincubation of MHETase with PETase affects PET turnover in a synergistic fashion. Taken together, this work provides additional insights into the mechanisms of action of the PETase and MHETase enzymes, which may open new avenue for bioremediation and removing plastics from the environment in a sustainable manner.Item The application of mass spectrometry in environmental chemistry: investigating biological cycling of arsenic, mercury and glycine betaine in aquatic ecosystems(Montana State University - Bozeman, College of Letters & Science, 2019) Alowaifeer, Abdullah Mohammed; Chairperson, Graduate Committee: Timothy R. McDermott; Brian Bothner (co-chair); Masafumi Yoshinaga, Patricia E. Bigelow, Brian Bothner and Timothy R. McDermott were co-authors of the article, 'Biological cycling of arsenic and mercury in Yellowstone Lake' which is contained within this thesis.; Qian Wang, Brian Bothner and Timothy R. McDermott were co-authors of the article, 'Examining the role of photoautotrophs contributing to glycine betaine, methylated amines and methane in oxic waters' which is contained within this thesis.Elemental cycling is a complex process that occurs abiotically and biotically. While abiotic cycling is well defined, biological cycling is more complex as it involves different microbes, animals and enzymes that govern its form and fate. In my project, I investigated the biological cycling of two of the most toxic elements known, arsenic and mercury. I examine their bioavailability, bioaccumulation and biomagnification in freshwater aquatic systems using Yellowstone Lake as a study model. In addtion, the sources and sinks of glycine betaine, an important aquatic metabolite that contributes to the carbon and nitrogen cycle, is investigated in Yellowstone Lake and three rivers located around the state of Montana. This research presented in this dissertation offers new insight on how arsenic and mercury cycle in aquatic systems and introduces a new hypothesis of the possible source of glycine betaine in freshwater ecosystem. Additionally, this project highlights a new and promising methodology to detect and quatify methylated amines in water samples.Item Bacterial community dynamics and variability in shallow aquifers(Montana State University - Bozeman, College of Letters & Science, 2019) Zelaya, Anna Jesus; Chairperson, Graduate Committee: Matthew Fields; Albert E. Parker, Kathryn L. Bailey, Ping Zhang, Joy Van Nostrand, Ning Daliang, Dwayne A. Elias, Jizhong Zhou, Terry C. Hazen, Adam P. Arkin and Matthew W. Fields were co-authors of the article, 'High spatiotemporal variability of bacterial diversity over short time scales with unique geohydrochemistry within a shallow, pristine aquifer' which is contained within this thesis.; Albert E. Parker, Kathryn L. Bailey, Ping Zhang, Joy Van Nostrand, Ning Daliang, Dwayne A. Elias, Jizhong Zhou, Terry C. Hazen, Adam P. Arkin and Matthew W. Fields were co-authors of the article, 'Population filtering in sediment biofilms from dynamic, source planktonic communities' which is contained within this thesis.; Sara Altenburg, Kathryn L. Bailey, Heidi J. Smith, Dwayne A. Elias and Matthew W. Fields were co-authors of the article, 'Community structure across particle size in-vitro and in-situ' which is contained within this thesis.; Heidi J. Smith, Frederick von Netzer and Matthew W. Fields were co-authors of the article, 'Contribution of total and viable DNA pools on diversity estimates of contaminated and non-contaminated subsurface sediments and groundwater' which is contained within this thesis.The shallow, terrestrial subsurface plays an important role in sustaining life above ground. Globally, subsurface environments are becoming increasingly threatened by anthropogenic sources of contamination and disturbance. The Oak Ridge Reservation (ORR) played an important role in the development of nuclear weapons during World War II. In the process, the underlying subsurface became contaminated with radioactive and hazardous wastes. Strategies to remediate polluted subsurface environments such as Oak Ridge have included natural attenuation by resident microbes such as bacteria. Such studies would be aided by a thorough understanding of the natural variability of microbial diversity over space and time in uncontaminated environments. We examined microbial community diversity and variability in both contaminated and non-contaminated sites of the ORR via ss-rRNA paired-end sequencing. An initial in-situ spatiotemporal survey of non-contaminated groundwater was conducted in order to understand how diversity changes over time in an undisturbed aquifer. Moreover, different models were used to estimate possible causal relationships between geochemical parameters and population distribution. Additionally, surrogate sediment samplers were filled with native sediment to assess the diversity of the attached bacterial fraction. Communities observed in the attached fraction were a subset of groundwater communities, although the dominant fractions of each were distinct. After initial assessment, in-vitro groundwater was used as both a nutrient source and microbial inoculum for bioreactors filled with glass beads of various sizes in order to understand particle size effects on community dynamics. Potential viability of resident microbes in both contaminated and non-contaminated groundwater and cored sediments was assessed using PMA-Seq and other complementary methods. Collectively, results show that 1) microbial communities in groundwater are highly dynamic over short timescales, 2) corresponding changes in geochemistry are mostly weakly related to changes in community structure (except perhaps after a disturbance or stress period), 3) community assembly may be affected by pore space volume, 4) PMA-viable populations differ between solid and aqueous fractions, 5) most subsurface cells are intact, and 6) traditional estimates of largely abundant populations may be influenced by the presence of DNA from non-viable members, resulting in less abundant populations being unmeasured or underestimated. The results of this study have implications for sampling and appropriate estimations of microbial populations in situ as well as the inherent variability in an uncontaminated shallow aquifer.Item Structural controls and chemical characterization of brecciation and uranium vanadium mineralization in the northern Bighorn Basin(Montana State University - Bozeman, College of Letters & Science, 2016) Moore-Nall, Anita Louise; Chairperson, Graduate Committee: David R. Lageson; Margaret Eggers, John Doyle, Myra Lefthand, Sara Young, Ada Bends, Anne Camper and CEHSC were co-authors of the article, 'Potential health risks from uranium in home well water: an investigation by the Apsaalooke (Crow) Tribal Research Group' in the journal 'GeoSciences' which is contained within this thesis.; Ranalda Tsosie was a co-author of the article, 'Ree data support oil with a Permian phosphoria formation source as a source of metals for U and V mineralization in the northern Bighorn Basin' submitted to the journal 'Minerals' which is contained within this thesis.The goals of this research were to determine if the mode of mineralization and the geology of two abandoned uranium and vanadium mining districts that border the Crow Reservation might be a source for contaminants in the Bighorn River and a source of elevated uranium in home water wells on the Reservation. Surface and spring waters of the Crow Reservation have always been greatly respected by the Crow people, valued as a source of life and health and relied upon for drinking water. Upon learning that the Bighorn River has an EPA 303d impaired water listing due to elevated lead and mercury and that mercury has been detected in the fish from rivers of the Crow Reservation this study was implemented. Watersheds from both mining districts contribute to the Bighorn River that flows through the Crow Reservation. Initial research used the National Uranium Resource Evaluation database to analyze available geochemistry for the study areas using GIS. The data showed elevated concentrations of lead in drainages related to the mining areas. The data also showed elevated uranium in many of the surface waters and wells that were tested as a part of the study on the Crow Reservation. The author attended meetings and presented results of the National Uranium Resource Evaluation data analyses to the Crow Environmental Health Steering Committee. Thus, both uranium and lead were added to the list of elements that were being tested in home water wells as part of a community based participatory research project addressing many issues of water quality on the Crow Reservation. Results from home wells tested on the reservation did show elevated uranium. Rock samples were collected in the study areas and geochemically analyzed. The results of the analyses support a Permian Phosphoria Formation oil source of metals in the two mining districts. Structural data support fracturing accompanied by tectonic hydrothermal brecciation as a process that introduced oil and brines from the Bighorn Basin into the deposits where the uranium vanadium deposits later formed.Item Effects of triclosan exposure on nitrification in activated sludge, biofilms, and pure cultures of nitrifying bacteria(Montana State University - Bozeman, College of Engineering, 2016) Bodle, Kylie Brigitta; Chairperson, Graduate Committee: Ellen LauchnorEmerging contaminants, such as pharmaceuticals or personal care products, have the potential to impact many wastewater treatment processes due to their antimicrobial properties. Nitrifying bacteria initiate the nitrogen removal process in wastewater treatment, and are particularly sensitive to inhibition by these and other contaminants. The impacts of the emerging contaminant triclosan (TCS) on two common nitrifying bacteria were evaluated under multiple growth conditions. The resilience of biofilms and suspended cell cultures of the ammonia oxidizing bacterium (AOB) Nitrosomonas europaea was compared during TCS exposure. Impacts of TCS on Nitrobacter winogradskyi, a common nitrite oxidizing bacterium (NOB), were also considered. Lastly, activated sludge biofilms and suspended cells were also exposed to TCS to further evaluate impacts on nitrification. Triclosan at part per million levels was found to reduce respiration in nitrifying biofilms, and NOB were much more impacted by TCS than AOB. Interestingly, biofilms of N. europaea were just as impacted by TCS as suspended cells. Triclosan adsorbed strongly to cellular material and degradation was only observed in activated sludge at low concentrations. Altogether, TCS was found to reduce nitrification by AOB and NOB, and the results suggest that its presence at high levels in wastewater treatment is likely to have negative consequences.Item Poplar River : Montana objectives and options for achieving them(Montana State University - Bozeman, 1984) Martin, Russell CurtisItem Community based risk assessment of exposure to waterborne contaminants on the Crow Reservation, Montana(Montana State University - Bozeman, College of Letters & Science, 2014) Eggers, Margaret Joy Slack; Chairperson, Graduate Committee: Anne Camper; Tim Ford (co-chair); Crescentia Cummins, John Doyle, Larry Kindness, Myra J. Lefthand, Urban J. Bear Don't Walk, Ada Bends, Susan C. Broadaway, Anne K. Camper, Roberta Fitch, Timothy E. Ford, Steve Hamner, Athalia R. Morrison, Crystal L. Richards and Sara L. Young were co-authors of the article, 'Community-based participatory research in Indian country: improving health through water quality research and awareness' in the journal 'Family and Community Health' which is contained within this thesis.; John T. Doyle and Margaret Hiza Redsteer were co-authors of the article, 'Exploring effects of climate change on Northern Plains American Indian health' in the journal 'Climatic change' which is contained within this thesis.The goal of this collaborative research project undertaken by the Crow Reservation community, Little Big Horn College and Montana State University Bozeman has been to improve the health of Crow community members by assessing, communicating and mitigating the risks from local waterborne contaminants. The Reservation's surface waters have always been greatly respected by the Crow people, valued as a source of life and health and relied upon for drinking water. About fifty years ago, rural families switched to home well water instead of hauling water from the rivers. Many families went from having an unlimited supply of free, good quality river water, to unpalatable well water dependent upon an expensive-to-maintain plumbing system. Tribal members questioned the health of the rivers and well water due to visible water quality deterioration and potential connections to illnesses and initiated this research project. We share what we have learned as tribal members and researchers about conducting community-based risk assessment and using our data to improve Tribal and river health. Initial research on river water quality revealed significant microbial contamination. Collaborations with several microbiologists revealed substantial E. coli and Cryptosporidium river contamination as well as Helicobacter pylori in home water supplies. We found that about 55% of home wells are unsafe to drink due to either mineral and/or microbial contamination. Depending on the river valley, 11% to 58% of home wells exceed the cumulative risk level of concern for mineral contaminants. Exposure to contaminated well water exacerbates the community's existing health disparities due to the confluence of the area's geology, extensive agriculture, lack of public environmental health education, jurisdictional complexities of reservations, already vulnerable health status and families' limited financial resources for mitigating poor quality well water. Limited resources as well as the links among ecosystems, cultural practices and public health will increase the already existing impacts of climate change on reservation communities. Flood frequency, late summer water shortage and fire severity are increasing while water quality is declining. Risk communication and risk mitigation, not just risk assessment, have been and continue to be central to our project and pursued through numerous venues and collaborations.Item Cadmium and lead removal with direct filtration(Montana State University - Bozeman, College of Engineering, 1984) Engleson, Thomas Paul