Earth Sciences

Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/43

By virtue of our outstanding location in the scenic and rugged mountains of southwest Montana, Earth Science students have many opportunities to participate in field trips that will facilitate the study of earth processes, earth resources, earth history, and environments that people have modified. These field trips are an integral part of many courses, as well as extracurricular activities sponsored by the department. Fieldwork is a very important component of our instructional programs at both the undergraduate and graduate levels.Because of the research conducted by faculty in the department, an undergraduate student may have the opportunity to work on active research projects. In particular, we offer the opportunity to do a "Senior Thesis" to our top students in each senior class. The senior thesis enables a student to work on an actual research project under the supervision of a faculty member, write a research report (a mini-thesis), and present the results at a professional conference. This is excellent preparation for graduate school and/or the workplace. Our Master's theses frequently involve field-testing of state-of-the-art hypotheses proposed elsewhere, as well as formulation of the next generation of hypotheses, which will shape our disciplines in the decades to come. Most Master's thesis work in the Department is published in the peer-reviewed professional literature after presentation at regional or national professional meetings.

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    Enhanced trace element mobilization by Earth’s ice sheets
    (Proceedings of the National Academy of Sciences, 2020-11) Hawkings, Jon R.; Skidmore, Mark L.; Wadham, Jemma L.; Priscu, John C.; Morton, Peter L.; Hatton, Jade E.; Gardner, Christopher B.; Kohler, Tyler J.; Stibal, Marek; Bagshaw, Elizabeth A.; Steigmeyer, August; Barker, Joel; Dore, John E.; Lyons, W. Berry; Tranter, Martyn; Spencer, Robert G. M.
    Trace elements sustain biological productivity, yet the significance of trace element mobilization and export in subglacial runoff from ice sheets is poorly constrained at present. Here, we present size-fractionated (0.02, 0.22, and 0.45 µm) concentrations of trace elements in subglacial waters from the Greenland Ice Sheet (GrIS) and the Antarctic Ice Sheet (AIS). Concentrations of immobile trace elements (e.g., Al, Fe, Ti) far exceed global riverine and open ocean mean values and highlight the importance of subglacial aluminosilicate mineral weathering and lack of retention of these species in sediments. Concentrations are higher from the AIS than the GrIS, highlighting the geochemical consequences of prolonged water residence times and hydrological isolation that characterize the former. The enrichment of trace elements (e.g., Co, Fe, Mn, and Zn) in subglacial meltwaters compared with seawater and typical riverine systems, together with the likely sensitivity to future ice sheet melting, suggests that their export in glacial runoff is likely to be important for biological productivity. For example, our dissolved Fe concentration (20,900 nM) and associated flux values (1.4 Gmol y−1) from AIS to the Fe-deplete Southern Ocean exceed most previous estimates by an order of magnitude. The ultimate fate of these micronutrients will depend on the reactivity of the dominant colloidal size fraction (likely controlled by nanoparticulate Al and Fe oxyhydroxide minerals) and estuarine processing. We contend that ice sheets create highly geochemically reactive particulates in subglacial environments, which play a key role in trace elemental cycles, with potentially important consequences for global carbon cycling.
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    Opportunities and Trade-offs among BECCS and the Food, Water, Energy, Biodiversity, and Social Systems Nexus at Regional Scales
    (2018-01) Stoy, Paul C.; Ahmed, Selena; Jarchow, Meghann; Rashford, Benjamin; Swanson, David; Albeke, Shannon; Bromley, Gabriel T.; Brookshire, E. N. Jack; Dixon, Mark D.; Haggerty, Julia Hobson; Miller, Perry R.; Peyton, Brent M.; Royem, Alisa; Spangler, Lee H.; Straub, Crista; Poulter, Benjamin
    Carbon dioxide must be removed from the atmosphere to limit climate change to 2°C or less. The integrated assessment models used to develop climate policy acknowledge the need to implement net negative carbon emission strategies, including bioenergy with carbon capture and storage (BECCS), to meet global climate imperatives. The implications of BECCS for the food, water, energy, biodiversity, and social systems (FWEBS) nexus at regional scales, however, remain unclear. Here, we present an interdisciplinary research framework to examine the trade-offs as well as the opportunities among BECCS scenarios and FWEBS on regional scales using the Upper Missouri River Basin (UMRB) as a case study. We describe the physical, biological, and social attributes of the UMRB, and we use grassland bird populations as an example of how biodiversity is influenced by energy transitions, including BECCS. We then outline a "conservation" BECCS strategy that incorporates societal values and emphasizes biodiversity conservation.
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    Pinus contorta invasions increase wildfire fuel loads and may create a positive feedback with fire
    (2017-03) Taylor, Kimberley T.; Maxwell, Bruce D.; McWethy, David B.; Pauchard, Anibal; Nunez, Martin A.; Whitlock, Cathy
    Invasive plant species that have the potential to alter fire regimes have significant impacts on native ecosystems. Concern that pine invasions in the Southern Hemisphere will increase fire activity and severity and subsequently promote further pine invasion prompted us to examine the potential for feedbacks between Pinus contorta invasions and fire in Patagonia and New Zealand. We determined how fuel loads and fire effects were altered by P. contorta invasion. We also examined post-fire plant communities across invasion gradients at a subset of sites to assess how invasion alters the post-fire vegetation trajectory. We found that fuel loads and soil heating during simulated fire increase with increasing P. contorta invasion age or density at all sites. However, P. contorta density did not always increase post-fire. In the largest fire, P. contorta density only increased significantly post-fire where the pre-fire P. contorta density was above an invasion threshold. Below this threshold, P. contorta did not dominate after fire and plant communities responded to fire in a similar manner as uninvaded communities. The positive feedback observed at high densities is caused by the accumulation of fuel that in turn results in greater soil heating during fires and high P. contorta density post-fire. Therefore, a positive feedback may form between P. contorta invasions and fire, but only above an invasion density threshold. These results suggest that management of pine invasions before they reach the invasion density threshold is important for reducing fire risk and preventing a transition to an alternate ecosystem state dominated by pines and novel understory plant communities.
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