Scholarship & Research
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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 Exploring the role of water in tree growth and what trees can tell us about the hydroclimate of the past(Montana State University - Bozeman, College of Letters & Science, 2018) Martin, Justin T.; Chairperson, Graduate Committee: David Roberts; Jia Hu (co-chair); Nathaniel Looker, Zachary Hoylman, Kelsey Jencso and Jia Hu were co-authors of the article, 'Hydrometeorology organizes intra-annual patterns of tree growth across time, space, and species in a montane watershed' in the journal 'New phytologist' which is contained within this thesis.; Nathaniel Looker, Zachary Hoylman, Kelsey Jencso and Jia Hu were co-authors of the article, 'Differences in the use of winter precipitation by conifers along an elevation gradient in the northern Rockies' submitted to the journal 'Global change biology' which is contained within this thesis.; Gregory Pederson, Connie Woodhouse, Edward Cook, Gregory McCabe and Kevin Anchukaitis were co-authors of the article, 'Unprecedented drought intensity tracks recent warming in the headwaters of the United States' largest river basin' submitted to the journal 'Nature climate change' which is contained within this thesis.Here, we revisit the role of water potential in tree growth control using a field-based approach to exploring the role of soil moisture supply and atmospheric moisture demand on tree water potential and subsequently, growth. We explore how limitation in tree radial growth can be well predicted by local hydrometeorlogical conditions and associated tree water potentials, and observe that such limitation occurs under conditions that are considerably more mesic than those associated with the onset of photosynthetic limitation resulting from stomatal regulation (Martin et al., 2017). While direct observation of tree xylem growth and growth limitation remains a very challenging problem, our findings provide strong evidence for the role of Psi x in the regulation of tree radial growth in dry environments...Because one of the most prominent features of observed climate change in the American West has been an advancement in the timing of spring conditions (Cayan et al., 2001; Stewart et al., 2005), developing a better understanding of how the timing of moisture delivery and tree growth relate is an important research goal. Using a field-based study carried out over three years in western Montana, we quantified the timing and magnitude of moisture delivery to a forest ecosystem, and coupled this to isotope-based observations of where in the soil profile trees sourced water from as well as the seasonal evolution of radial growth. This allowed us to estimate the importance of winter precipitation relative to summer rains for growth in trees over the growing season. This work establishes a baseline understanding of how temporal dynamics of moisture delivery to forests and tree growth relate in time and can help guide our understanding of how ongoing changes to climate conditions may affect tree growth in the future...In order to better understand the hydroclimatic dynamics of the Missouri river, we developed a network of tree ring based reconstructions of streamflow spanning 1200 years for every major tributary across the mountain headwaters of the Missouri river. We examined the history of basin-wide drought events evident in the tree ring record in the context of reconstructed temperature and explored how the relationship between temperature and streamflow has changed over time. As a result, it is evident that rising temperatures create new challenges for water managers and users in the Upper Missouri River Basin that are likely to increase as temperatures warm in the future.Item 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 Limiting factors for trout populations in the upper Clark Fork River superfund site, Montana(Montana State University - Bozeman, College of Letters & Science, 2013) Mayfield, Mariah Pine; Chairperson, Graduate Committee: Thomas E. McMahonLarge-scale heavy metal contamination of the upper Clark Fork River from mining deposits has created significant damage to aquatic habitat in the drainage. Trout are present in the system, although with abundances lower than expected. The objectives of this study were to identify critical habitat areas and to identify conditions that continue to limit both native and nonnative trout populations, with the focus of the study on the lingering environmental effects caused by high heavy metal concentrations. A radiotelemetry study, with 256 tagged brown trout Salmo trutta, westslope cutthroat trout Oncorhynchus clarkii lewisi, and cutthroat/rainbow hybrid trout, was conducted from 2009 to 2011. The radiotelemetry relocation data was used to determine temporal and spatial patterns in movement and survival rates in relation to heavy metals and other environmental factors, and to identify critical habitat areas (e.g., spawning locations and overwintering areas). Brown trout spawning occurred in numerous tributaries throughout the basin and in the upper reaches of the mainstem. Cutthroat trout spawned only in tributaries, and these tributaries were often smaller and more degraded by land use practices than brown trout spawning tributaries. Multistate mark-recapture survival analysis estimated that survival is lowest in the stream segment with the greatest amount of heavy metal contamination; the weekly likelihood of survival was estimated at 0.97 (95% confidence interval 0.97 - 0.98) for brown trout and 0.90 (95% confidence interval 0.84 - 0.97) for cutthroat trout. Additionally, weekly survival estimates for cutthroat trout in tributaries was also low (0.92; 95% confidence interval 0.87 - 0.94), likely because of anthropogenic land use pressures. Very limited movement was observed, except in relation to spawning migrations. Cutthroat trout moved greater distances and at a higher rate than brown trout. The results from this study indicate that the remaining mining contamination continues to reduce trout survival rates throughout the basin and should be removed in order to increase trout densities. Additionally, restoration priority should be placed on tributaries that are negatively affected by land use pressures.