A single link to the first track to allow the export script to build the search page
  • Undergraduate Poster Abstracts
  • Earth Sciences/Other Physical Sciences

    FRI-903 AUTOCHAMBER MEASUREMENTS OF NET ECOSYSTEM (CO2) EXCHANGE AT A SUBARCTIC MIRE IN NORTHERN SWEDEN

    • Maeah Walthall ;
    • Xavier Parker-Smith ;
    • Ryan Lawrence ;

    FRI-903

    AUTOCHAMBER MEASUREMENTS OF NET ECOSYSTEM (CO2) EXCHANGE AT A SUBARCTIC MIRE IN NORTHERN SWEDEN

    Maeah Walthall1, Xavier Parker-Smith2, Ryan Lawrence3.

    1George Mason University, Fairfax, VA, 2North Carolina Agricultural and Technical State University, Greensboro, NC, 3University of New Hampshire, Durham, NH.

    Northern latitude wetlands, approximately 50 °N, are characterized by cold and wet conditions that result in low decomposition rates for plant litter. This process promotes the sequestration of carbon (C) in the form of organic matter (i.e., peat) and the formation of widespread peatlands. Peatlands, particularly in the Northern Hemisphere, have accumulated C by removing atmospheric CO2 for approximately the past 10,000 years. Historically, peatlands represent a net C sink; however, increases in the global average temperature could alter peatlands' ability to store carbon. With a warming climate and permafrost thaw, the pool of once stable soil organic C available for decomposition is increasing. Like all terrestrial ecosystems, a number of environmental factors such as peat temperature and vegetation play important roles in governing the fate of C in peatlands. Projected climate change is expected to affect these regulating factors. Subarctic peatlands in zones of discontinuous permafrost are experiencing widespread environmental changes due to climate warming. In this study, we present net ecosystem (CO2) exchange and δ13C-CO2 data from Stordalen Mire in northern Sweden (68°22’ N, 19°03’ E). Measurements were made using a quantum cascade laser spectrometer connected to automatic chambers placed in the 3 predominant ecosystems: a dry, elevated Palsa; an intermediate thaw regime dominated by Sphagnum spp.; and a completely thawed, inundated site dominated by Eriophorum angustifolium.

    THU-906 A HIGH-PRESSURE INFRARED SPECTROSCOPIC STUDY OF CHROMIUM PYROPHOSPHATE TO 18 GPA

    • Nicolas Blanc ;
    • Quentin Williams ;

    THU-906

    A HIGH-PRESSURE INFRARED SPECTROSCOPIC STUDY OF CHROMIUM PYROPHOSPHATE TO 18 GPA

    Nicolas Blanc, Quentin Williams.

    University of California, Santa Cruz, Santa Cruz, CA.

    The infrared spectra of chromium pyrophosphate, Cr2P2O7, have been studied under pressures up to approxomately18 GPa. Cr2P2O7 is a prospective battery component, and understanding its behavior under volumetric compression can lead to insights into possible behavior-modulating chemical substitutions. Our study explored the compound's response to pressure by investigating the shifts of vibrational modes under compression and pressure-induced phase transitions occurring within the crystal lattice. Our preliminary results constrain the pressure response of the symmetric and asymmetric bending and stretching modes of the tetrahedrally coordinated PO4-phosphate groups between 600 to 800 cm-1, and 950 to 1,200 cm-1, respectively. Modes show a normal constant shift to higher frequencies with pressure up to approximately 4 GPa where a transition occurs. At ambient pressures, 7 bands are resolvable at 1,190, 1,150, 1,100, 1,060, 1,030, 1,015, and 950 cm-1, but only the 4 lowest frequency modes persist to the highest pressure of our experiment (18 GPa). At this pressure, these modes are at 1,100, 1,070, 1,030, and 990 cm-1, respectively. The 3 lower frequency bands between 600 and 800 cm-1 are resolvable at pressures up to approximately 6 GPa. At higher pressures, these modes appear to merge into one broad band near 740 cm-1. Decompression data suggests that all bands, except one at approximately 730 cm-1, reappear. Our results indicate that a phase transformation occurs within the lattice of Cr2P2O7 at approximately 4 GPa and is likely associated with a subtle shift in crystallographic symmetry.

    FRI-906 DIVERSITY OF MICROORGANISMS IN A TACONITE TAILINGS BASIN IN NORTHERN MINNESOTA

    • Charles Thunder ;
    • Daniel Jones ;
    • Jake Bailey ;

    FRI-906

    DIVERSITY OF MICROORGANISMS IN A TACONITE TAILINGS BASIN IN NORTHERN MINNESOTA

    Charles Thunder1, Daniel Jones2, Jake Bailey2.

    1Minneapolis Community and Technical College, Minneapolis, MN, 2University of Minnesota, Minneapolis, MN.

    Little is known about the microbial biogeochemistry and diversity of taconite tailings basins. Taconite tailings are fine-grained waste materials that are separated from iron ore during the taconite mining process. Tailings are removed from the taconite processing facility in a slurry and piped out to a basin for permanent storage. The water is reclaimed, collected in a return cell, and reused in the refinement processes. Taconite tailings basins represent a unique biogeochemical environment with circumneutral pH (7 - 8), very little organic matter, and include both oxidized and reduced sulfur and iron in aqueous and mineral phases. We are investigating the presence and diversity of microorganisms in a taconite tailings basin near Mountain Iron, Minnesota. In June 2015, the Minnesota Department of Natural Resources (DNR) collected shallow cores (up to 4 m length) with a Giddings probe from multiple locations in the basin. Within a day of collection, we sampled the cores at various depths, and are now in the process of describing the microbial communities using culture-independent methods. Preliminary results indicate that the tailings harbor low microbial biomass (< 106 cells/g sediment). Gene sequencing, rRNA, is in progress and will reveal the identity and diversity of the microorganisms. Our findings will help us begin to understand the biological processes that are occurring in the basin which will help interpret sulfur and iron biogeochemistry and may suggest novel reclamation and mitigation strategies.

    FRI-902 RECONSTRUCTING CRYOGENIAN MARINE OXYGEN LEVELS FROM LIMESTONE SUCCESSIONS IN MONGOLIA

    • Nicole A. O'Keefe ;
    • Kimberly V. Lau ;
    • Francis A. Macdonald ;
    • Jonathan L. Payne ;

    FRI-902

    RECONSTRUCTING CRYOGENIAN MARINE OXYGEN LEVELS FROM LIMESTONE SUCCESSIONS IN MONGOLIA

    Nicole A. O'Keefe1, Kimberly V. Lau2, Francis A. Macdonald3, Jonathan L. Payne2.

    1Saint Mary's College of California, Moraga, CA, 2Stanford University, Stanford, CA, 3Harvard University, Cambridge, MA.

    Variation in oxygen availability has been an important control on the evolution of life over geological time. Earth’s atmosphere first became oxygenated 2.4 Gya, but the nature and trajectory of the rise to present-day levels and its relationship to the origin and early evolution of animals remain poorly constrained. In the Cryogenian Period (720 to 635 Ma), the Earth was nearly covered in glaciers during the Sturtian and the Marinoan Snowball Earth events. The earliest fossil evidence of animals also occurs during this interval. To assess marine oxygen concentrations during Cryogenian time, we analyzed trace metal concentrations, uranium(U), molybdenum(Mo), and vanadium (V), in limestone collected from 2 stratigraphic sections in Mongolia, representing different facies belts. By measuring trace metal concentrations from the 2 locations, we are better able to differentiate between chemical alteration and variations in Cryogenian seawater chemistry. Above the Sturtian glacial deposits, U, Mo, and V are elevated and then decrease coincident with a large negative δ13C excursion. These data indicate a post-Sturtian shift toward higher oxygenation levels in the oceans, followed by a return to anoxic conditions coincident with a large perturbation to the carbon cycle. This temporary oxygenation may provide a link between the expansion of habitable seafloor and the rise of complex metazoans.

    THU-902 THE EFFECTS OF OXYGEN ON GROWTH AND SIZE IN MODERN BENTHIC FORAMINIFERA FROM THE SANTA MONICA BASIN

    • Mariah Green ;
    • Caitlin Keating-Bitonti ;
    • Jonathan L. Payne ;

    THU-902

    THE EFFECTS OF OXYGEN ON GROWTH AND SIZE IN MODERN BENTHIC FORAMINIFERA FROM THE SANTA MONICA BASIN

    Mariah Green1, Caitlin Keating-Bitonti2, Jonathan L. Payne2.

    1Northeastern Illinois University, Chicago, IL, 2Stanford University, Stanford, CA.

    The ocean is a diverse environment. Although areas of the ocean might be considered too harsh for life, almost no environment is uninhabited. For example, meiofauna dominate anoxic environments even though macrofauna rarely occur here because body size determines the amount of oxygen required for metabolism. The Santa Monica Basin (SMB), located off Southern California, is an oxygen minimum zone (OMZ) where we can study the response of size to oxygen availability. Foraminifera are single-celled organisms occurring in most marine environments that are sensitive to environmental change, making them ideal for investigating their size response to oxygen conditions within natural ecosystems. We hypothesized that benthic foraminifera living in anoxic waters will have a reduced test volume with fewer chamber numbers than those living in more oxygenated waters. We collected 4 species of rotaliid foraminifera from core tops at 11 locations in SMB: Bolivina argentea, B. spissa, Loxostomum pseudobeyrichi, and Uvigerina peregrina. We grouped the sites based on their oxygen levels into low-oxygen, suboxic, dysoxic, and anoxic conditions. Contrary to our hypothesis, U. peregrina shows a negative correlation between test volume and oxygen concentration, while L. pseudobeyrichi and B. spissa show little variation in test volume between sites. Only B. argentea exhibits a positive correlation between test volume and oxygen concentration. Our results show that foraminiferal species have unique morphological responses to variations in oxygen. Although oxygen is an important energy source, additional variables, such as ecological interactions or food availability might be influencing the individual species trends observed in the SMB.

    FRI-923 DYNAMIC EARTHQUAKE TRIGGERING OF LONG PERIOD EVENTS IN THE SAN MIGUEL VOLCANO

    • David Soto ;
    • Aaron Velasco ;

    FRI-923

    DYNAMIC EARTHQUAKE TRIGGERING OF LONG PERIOD EVENTS IN THE SAN MIGUEL VOLCANO

    David Soto, Aaron Velasco.

    The University of Texas at El Paso, El Paso, TX.

    Do earthquakes and volcanoes interact? Earthquakes generate dynamic stresses that can disturb the local stress field in an area and remotely trigger seismicity more than 2 fault lengths away from an epicenter. The internal state and activity of an active volcano may be sensitive to the passage of seismic energy. The San Miguel volcano located in El Salvador is a highly active stratovolcano that last erupted in December 2013. San Miguel has not been extensively studied and presents a significant hazard to the region because of its active release of volcanic gases, historic flank eruptions, and fissure activity. To investigate the internal processes of the volcano, we used data collected from a network of 6 UTEP seismic sensors recording ground movement from 2007-2008 located around the volcano. Manually analyzing waveform data, we found 9 regional earthquakes that appear to have triggered a long-period response from the volcano, typically during the passage of the surface waves. We compared 5 earthquakes of similar magnitude and distance that did not trigger a long-period signal. These earthquakes lacked a strong surface-wave signal based on the (LG/P) ratio. We conclude that the long-period response of the volcano was triggered by the interaction of the volcano and the abrupt surface waves of the regional earthquakes. Currently we are investigating mechanisms for this long-period response.