Theses and Dissertations at Montana State University (MSU)
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Item Tracing interactions of hydrogeology and land use in two Montana watersheds(Montana State University - Bozeman, College of Agriculture, 2024) Keeshin, Skye Ilan; Chairperson, Graduate Committee: Stephanie A. EwingHydrogeologic systems dictate the introduction, transport, processing, and mixing of groundwaters, with implications for both groundwater and surface water quality. Land use can transform hydrogeologic processes and water quality through contributions of human amendments, alteration of soil and aquifer materials, and redistribution and consumption of water resources. Groundwater transit times are also orders of magnitude longer than those of surface water systems, resulting in lag times in water quality changes. In this thesis, I examine water quality consequences of land use in Montana at two headwater sites using geochemical tracers in groundwater and surface water. The first is within the Powder River Basin, the largest coal producing region in the US, where manmade aquifers composed of spoils from mine overburden replace existing unconsolidated and bedrock aquifers with salinity effects on downgradient waters. In a reclaimed coulee supplying groundwater to Rosebud Creek, a tributary of the Yellowstone River, geochemical and isotopic tracers reveal lateral contributions that contribute to dilution of high salinity mine-derived waters. These contributions include local inputs from shallow unconsolidated and bedrock aquifers and inputs of water on the order of 10,000 years from regional bedrock systems. The second site is the Gallatin Valley, a rapidly urbanizing intermountain basin in the Upper Missouri headwaters, where groundwater and surface water transects reveal mixing of water with a range of ages from a few years to 100,000 years. While not associated with spatial variation in nitrate concentration, these contributions likely attenuate rising nitrate concentrations in the valley aquifer as a whole over time, reflecting spatially variable loading from a legacy of agricultural fertilization and increasingly prevalent septic wastewater systems. A large component of the Gallatin Valley aquifer is decades old water sourced from higher elevation precipitation, consistent with long travelled mountain front stream losses. This component may diminish over time with an increasingly limited snowpack. Overall, hydrogeologic systems in these two land use regimes limit but do not eliminate effects of human-derived water quality concerns, and documenting them will improve water quality forecasting with impending changes in snowpack and precipitation.Item Rock powered life in the Samail ophiolite: an analog for early Earth(Montana State University - Bozeman, College of Agriculture, 2021) Fones, Elizabeth Marie; Chairperson, Graduate Committee: Eric Boyd; Daniel R. Colman, Emily A. Kraus, Daniel B. Nothaft, Saroj Poudel, Kaitlin R. Rempfert, John R. Spear, Alexis S. Templeton and Eric S. Boyd were co-authors of the article, 'Physiological adaptations to serpentinization in the Samail ophiolite, Oman' in the journal 'The International Society for Microbial Ecology journal' which is contained within this dissertation.; Daniel R. Colman, Emily A. Kraus, Ramunas Stepanauskas, Alexis S. Templeton, John R. Spear and Eric S. Boyd were co-authors of the article, 'Diversification of methanogens into hyperalkaline serpentinizing environments through adaptations to minimize oxidant limitation' in the journal 'The International Society for Microbial Ecology journal' which is contained within this dissertation.; David W. Mogk, Alexis S. Templeton and Eric S. Boyd were co-authors of the article, 'Endolithic microbial carbon cycling activities in subsurface mafic and ultramafic igneous rock' which is contained within this dissertation.Serpentinization is a geochemical process wherein the oxidation of Fe(II)-bearing minerals in ultramafic rock couples with the reduction of water to generate H 2, which in turn can reduce inorganic carbon to biologically useful substrates such as carbon monoxide and formate. Serpentinization has been proposed to fuel a subsurface biosphere and may have promoted life's emergence on early Earth. However, highly reacted waters exhibit high pH and low concentrations of potential electron acceptors for microbial metabolism, including CO 2. To characterize how serpentinization shapes the distribution and diversity of microbial life, direct cell counts, microcosm-based activity assays, and genomic inferences were performed on environmental rock and water samples from the Samail Ophiolite, Oman. Microbial communities were shaped by water type with cell densities and activities generally declining with increasing pH. However, cells inhabiting highly reacted waters exhibited adaptations enabling them to minimize stresses imposed by serpentinization, including preferentially assimilating carbon substrates for biomolecule synthesis rather than dissimilating them for energy generation, maintaining small genomes, and synthesizing proteins comprised of more reduced amino acids to minimize energetic costs and maximize protein stability in highly reducing waters. Two distinct lineages of a genus of methanogens, Methanobacterium, were recovered from subsurface waters. One lineage was most abundant in high pH waters exhibiting millimolar concentrations of H2, yet lacked two key oxidative [NiFe]-hydrogenases whose functions were presumably replaced by formate dehydrogenases that oxidize formate to yield reductant and CO 2. This allows cells to overcome CO 2/oxidant limitation in high pH waters via a pathway that is unique among characterized Methanobacteria. Finally, gabbro cores from the Stillwater Mine (Montana, U.S.A) were used to develop methods for detecting the activities of cells inhabiting mafic to ultramafic igneous rocks while controlling for potential contaminants. Optimized protocols were applied to rock cores from the Samail Ophiolite, where rates of biological formate and acetate metabolism were higher in rocks interfacing less reacted waters as compared with more extensively reacted waters, and in some cases may greatly exceed activities previously measured in fracture waters. This dissertation provides new insights into the distribution, activities, and adaptations exhibited by life in a modern serpentinizing environment.Item Geochemical characterization of shallow sediments from the grounding zone of the Whillans Ice Stream(Montana State University - Bozeman, College of Agriculture, 2019) Roush, Kimberly Anne; Chairperson, Graduate Committee: John C. Priscu and John Dore (co-chair); John Priscu, Mark Skidmore, Alex Michaud and the WISSARD Science Team were co-authors of the article, 'Signatures of subglacial water in shallow sediments of the Whillans grounding zone and overlying water column' which is contained within this thesis.; John Priscu, John Dore, Wei Li, Tristy Vick-Majors and the WISSARD Science Team were co-authors of the article, 'Sediment porewater organic matter content' which is contained within this thesis.The research presented in this thesis focused on subglacial flow beneath the West Antarctic Ice Sheet (WAIS) and its potential influence near the grounding zone. Antarctic grounding zones are of specific scientific interest because they can impact the stability of the continental ice sheet and its breakup, potentially resulting in significant sea level rise. My major objective was to determine whether there was influence of subglacial water at the Whillans Grounding Zone (WGZ) on the Siple Coast of the WAIS. A gravity corer was used to collect a 70 cm sediment core through 780 m of ice borehole drilled using a hot water clean access drilling system. The core was collected in a marine embayment adjacent to the WGZ beneath a 10 m water column. I used a combination of geochemical, isotopic and organic matter analyses to characterize the benthic sediments, porewater and water column. The geochemical and isotopic data showed the influence of subglacial freshwater on sediment porewater at specific depths in the 70 cm core. Vertical gradients of chloride and sulfate between surficial sediment and the overlying water column indicated ion diffusion from porewater to the column water. Dissolved organic matter concentration of sediment porewater and the overlying water column also indicated upward diffusion occurs from porewater to the overlying seawater. Sediment particulate carbon and nitrogen data showed that benthic sediments were more depleted in nitrogen than the overlying seawater. Sediment particulate carbon and nitrogen data showed that benthic sediments were more depleted in nitrogen than the overlying seawater. Geochemical, isotopic and organic matter data supports the influence of subglacial freshwater at the WGZ.Item SR and U isotopes reveal interactions of surface water and groundwater along the mountain headwaters to intermountain basin transition (Hyalite Canyon and Gallatin Valley, MT)(Montana State University - Bozeman, College of Agriculture, 2018) Miller, Florence Rita; Chairperson, Graduate Committee: Stephanie A. Ewing; Stephanie A. Ewing, Robert A. Payn, James B. Paces, Sam Leuthold and Stephan Custer were co-authors of the article, 'SR and U isotopes reveal the influence of lithologic structure on stream-groundwater interaction along a mountain headwater catchment (Hyalite Canyon, MT)' submitted to the journal 'Water resources research' which is contained within this thesis.; Stephanie A. Ewing, Robert Payn, Sam Leuthold, Stephan Custer, Tom Michalek and James B. Paces were co-authors of the article, 'SR and U isotopes reveal mixing patterns of groundwater and surface water influenced by human management in an intermountain basin (Gallatin Valley, MT)' submitted to the journal 'Journal of hydrology' which is contained within this thesis.Mountainous regions of the western United States are characterized by steep, rapidly eroding mountain headwater streams transitioning to more depositional intermountain basins. The character and flux of water across these process domains is subject to projected changes in mountain headwater snowpack and agricultural and urban land use in rapidly developing intermountain basins. Here we evaluate controls on water/rock, water/substrate, and surface/groundwater interactions within Hyalite Creek and the Gallatin Valley of southwest Montana. We use solute loads and geochemical tracers (87 Sr/86 Sr, Ca/Sr, and [234U/238U]) as indicators of such interactions. Surface water, groundwater, and soil samples were collected between 2016 and 2018. Stream water in upper Hyalite Creek had low 87 Sr/86 Sr values typical of volcanic and sedimentary host rock units, and low [234 U/238 U] values consistent with shorter flow path soil, shallow aquifer or runoff water. Middle Hyalite Creek had increased [234 U/238 U] values, reflecting groundwater inflows from the Madison Group limestones. Lower Hyalite Creek had an increase in 87 Sr/86 Sr values and decrease in [234 U/238 U] values, indicated contributions from Archean gneiss fracture flow. Using mixing models, we estimate inflows from the Madison contribute ~4% during summer baseflow conditions and inflows from the Archean contribute ~2% to ~8% of streamflow during summer and winter baseflow conditions. At the mountain front, diverse Ca/Sr, 87Sr/86Sr, and [234U/238U] ratios were observed as a result of convergent flow in mountain headwaters catchments. In the intermountain basin, divergent flow at the mountain front recharges valley aquifers and combines with infiltration through soils. With distance down-valley, we observe intermediate values of Ca/Sr, 87 Sr/86 Sr, and [234 U/238 U], suggesting mixing of diverse source waters. Higher concentrations of Sr, alkalinity, and Ca/Sr and 87 Sr/86 Sr ratios consistent with soil carbonates suggest water infiltration through soil facilitated the influence of soil secondary carbonates on groundwater geochemistry. Additionally, increased water movement through soil facilitates the increase in anthropogenic loading of NO3- and Cl- in surface and groundwaters. Our results provide novel quantification of groundwater contribution to streamflow in mountain headwaters, and elucidate water quality and quantity controls from the mountain front across the intermountain basin, including valley aquifer recharge, infiltration through soils, and anthropogenic solute influxes to groundwater.Item The geochemical evolution of the Cerro Uturuncu magma chamber, sw Bolivia and its relation to the Andean Central Volcanic Zone(Montana State University - Bozeman, College of Letters & Science, 2015) Michelfelder, Gary Scott; Chairperson, Graduate Committee: Todd Feeley; Todd C. Feeley and Alicia D. Wilder were co-authors of the article, 'The volcanic evolution of Cerro Uturuncu: a high-K, composite volcano in the back-arc of the central Andes of sw Bolivia' in the journal 'International journal of geosciences' which is contained within this thesis.; Todd C. Feeley was a co-author of the article, 'Crustal differentiation processes at Cerro Uturuncu, Andean central volcanic zone, sw Bolivia: insights from in situ SR isotopic analyses of plagioclase phenocrysts' submitted to the journal 'Geosphere' which is contained within this thesis.; Todd C. Feeley, Alicia D. Wilder and Erik C. Klemetti were co-authors of the article, 'Modification of the continental crust by subduction zone magmatism and vice-versa: across-strike geochemical variations of silicic lavas from individual eruptive centers in the Andean central volcanic zone' in the journal 'Geosciences' which is contained within this thesis.Cerro Uturuncu is a composite volcano located in the back-arc of the Andean Central Volcanic Zone (22.27°S, 67.18°W). The volcano has exclusively erupted crystal-rich andesite and dacite lava flows over the ~800,000 year life span of eruptive activity. This study provides new bulk-rock major- and trace- element, 18 O/16 O isotope ratios, Sr, Nd, and Pb radiogenic isotopic ratios of lava flows, domes, magmatic inclusions and xenoliths. The study also adds major and trace element and Sr isotopic ratios of plagioclase phenocrysts in order to examine the evolution of the magmatic plumbing system beneath Cerro Uturuncu and place the volcanic center in the regional context of the CVZ. Plagioclase crystals from silicic (andesitic to dacitic) lavas and domes at Volcan Uturuncu exhibit large variations in An contents, textures, and core to rim 87 Sr/86 Sr ratios. Many of the isotopic variations cannot have existed at magmatic temperatures for more than a few thousand years. The crystals likely derived from different locations in the crustal magmatic system and mixed just prior to eruption. Uturuncu magmas initially assimilated crustal rocks with high 87 Sr/86 Sr ratios. The magmas were subsequently modified by frequent recharge of more mafic magmas with lower 87 Sr/86 Sr ratios. A typical Uturuncu silicic magma therefore only attains its final composition just prior to or during eruption. On an arc-wide scale silicic lavas erupted from three well-characterized composite volcanoes between 21°S and 22°S (Aucanquilcha, Ollague, and Uturuncu) display systematically higher K 2O, LILE, REE and HFSE contents and 87 Sr/86 Sr ratios with increasing distance from the arc-front. In contrast, the lavas have systematically lower Al 2O 3, Na 2O, Sr, and Ba contents; LILE/HFSE ratios; 143 Nd/144 Nd ratios; and more negative Eu anomalies. Silicic magmas along the arc-front apparently reflect melting of relatively young, mafic composition amphibolitic source rocks with the continental crust becoming increasingly older with a more felsic bulk composition toward the east. This results from progressively smaller degrees of mantle partial melting, primary melt generation, and crustal hybridization with distance from the arc-front.Item Some geochemical aspects of the cedar tree laccolith, Gallatin Canyon, Southwestern Montana(Montana State University - Bozeman, College of Letters & Science, 1956) Hawkins, Daniel B.Item Geochemistry and provenance of Archean metasedimentary rocks in the southwestern Beartooth Mountains(Montana State University - Bozeman, College of Letters & Science, 1986) Thurston, Peter BouckItem Relationships among geochemical processes and microbial community structure in a unique high-arsenic, sulfidic geothermal spring in Yellowstone National Park(Montana State University - Bozeman, College of Agriculture, 2007) Taylor, William 'Peyton'; Chairperson, Graduate Committee: William P. Inskeep.The metabolisms of chemotrophic microorganisms are linked with the geochemical transformation of redox-active chemical species and mineral precipitation-dissolution reactions in geothermal environments. The objectives of the current work were to correlate the spatial distribution of microbial populations with changes in aqueous geochemistry and mineralogy in a unique Yellowstone National Park (YNP) geothermal spring, and to cultivate thermophilic microorganisms with phylogenetic and metabolic relevance to spring conditions. The geothermal spring (hereafter referenced as Joseph's Coat Spring -JC3) contains the highest reported concentrations of arsenic, antimony and thiosulfate of any geothermal feature studied in YNP. A suite of analytical and molecular approaches including aqueous geochemical and dissolved gas analysis, solid phase characterization, energetic calculations, microscopy and 16S rRNA gene sequence distribution were utilized to correlate specific microbial populations with biogeochemical processes. Predominant geochemical changes observed within the outflow channel were disappearance of methane, dissolved sulfide and ingassing of dissolved oxygen. Oxidation of arsenite was significant within the outflow channel despite the slow ingassing rates of dissolved oxygen. Microbial 16S rRNA gene sequences were determined at locations in the source pool and within the outflow channel.Item Biogeochemical gradients and energetics in geothermal systems of Yellowstone National Park(Montana State University - Bozeman, College of Agriculture, 2006) Ackerman, Galena Gene; Chairperson, Graduate Committee: William P. Inskeep.The fate and behavior of redox-active chemical species in geothermal systems is linked with the metabolic processes of chemotrophic thermophilic microorganisms. The major goal of the current work was to perform a thorough geochemical analysis of redox active species in geothermal outflow channels, and utilize these measurements to quantify the Gibbs free energy (?Grxn) values for numerous oxidation-reduction reactions that represent potential chemolithotrophic metabolisms. Insights gained from energetic analyses can be used to structure hypotheses regarding novel microbial metabolisms and to guide cultivation strategies for isolating relevant microorganisms. A comprehensive suite of geochemical parameters, including major ions, trace elements, redox-active species and dissolved gases, were analyzed and monitored in vertical transects of 11 geothermal outflow channels in Yellowstone National Park from 2003-2005. The geothermal springs chosen for this study contained strikingly different aqueous and solid-phase geochemistry. These systems exhibited a wide range of conditions, including ranges in pH (2.7 to 7.0), temperature (60 oC to 92 oC), Cl- (0.01 to 23 mM)), SO42- (0.4 to 7.5 mM), NH4+ (0.02 to 5.7 mM), CO2 (aq) (0.1 to 4.5 mM), Fe (0.2 to 230 uM), and As (0.03 to 130 uM)