Stable isotopes in water are affected by meteorological regimes and atmospheric conditions that can provide a unique identifier of their origin. Analyzing the composition, concentration, and stratigraphic distribution of δ18O in ice cores is an effective method for paleoclimate reconstructions that has been demonstrated in numerous sites, most famously in the ice sheets of Antarctica and Greenland, but in small alpine glaciers as well (e.g., the high Andes). δ18O in well-preserved ice can be used as a proxy for temperature, and with ancillary geochemical data for piecing together a record of hydroclimate change. Prior to the research that was conducted in the Wind River Range (WY), mid-latitude glaciers were thought to have minimal potential to reveal reliable information on paleoclimate. The uncertainties are generally attributed to meltwater percolation effects and the broad range of oxygen isotope abundances as a response to higher seasonal variability in these regions. In this paper, I discuss: (a) the basic processes and controls of oxygen isotope speciation, (b) paleoclimate applications of δ18O to polar ice sheets, (c) the motivation behind applying δ18O geochemistry to ice cores from the Wind River Range, (d) the calibration and geochronology methods specifically used in these mid-latitude glaciers, and (e) key evidence of the Little Ice Age from Wind River ice cores, including a the development of a refined age-model created from δ18O and electrical conductivity measurements, and a transfer-function used to establish mean annual temperature changes using δ18O.
SEDIMENT BUDGET ANALYSIS: LOUISVILLE YACHT CLUB MARINA
In this report, a sediment budget analysis is being performed for the Louisville Yacht Club Marina in Louisville, Kentucky. Using a number of tracers contained within sediment at the Yacht Club location, we will be performing an analysis to determine from which sources sediment is being eroded and ultimately deposited at the location of interest. We have identified the Ohio River and Pond Creek as sources in this analysis. Using samples from the Yacht Club and these two sources, we aim to determine through statistical means (t-testing) which tracers we can best help us identify the proportions of sediment from each source that are contributing to the total. Iron, Potassium, Nickle, and Zinc were identified as tracers that could be used in a simple unmixing model to ultimately identify the proportions of sediment being contributed to the deposition at the Yacht Club. This process concluded that roughly 30% of that sediment was contributed from the Ohio River, and roughly 70% was being contributed by Pond Creek. Leading to the conclusion of Pond Creek being the dominant source of sediment load production, using that we calculate the sediment yield for the marina.
A HOLOCENE PALEOENVIRONMENTAL RECONSTRUCTION OF A UNIQUE AMAZONIAN LANDSCAPE USING LAKE AND RIA SEDIMENTS
The Xingu River is the third largest tributary to the Amazon River and the second largest clear water river system in South America. Climate change and the impending construction of the Belo Monte dam pose complex threats to the Xingu River, its biodiversity, and the people that rely on its ecosystem services. However, the late Quaternary history of this lower Amazonian landscape is largely unknown, and therefore the response of the region to future environmental change is unclear. This study is centered on a 122 cm sediment core that was extracted from a floodplain lake within the Volta Grande, a large bend in the Xingu River upstream of the prominent Xingu ria. Here, we integrate sedimentological, geochemical, and chronological data to determine how this lake has evolved, which may improve predictions of how the Xingu River system will respond to disturbances in the Anthropocene. The sediment core was dated using radiocarbon and optically stimulated luminescence techniques. A multi-proxy analysis of the core involved measuring magnetic susceptibility, carbonate coulometry, total organic carbon, and major and trace element geochemistry from energy dispersive x-ray fluorescence. Data was collected at a 2 cm interval, in order to capture variability with high resolution. By incorporating multiple approaches to sediment analysis, the capacity to evaluate geomorphological and paleoenvironmental change is greatly increased. The core represents a depositional record of the mid-Holocene to present (~7000 yrs). Lithostratigraphic, geochemical, magnetic data indicate that topographic closure and lake formation was achieved by ~4800 yrs BP. Three chemostratigraphic units have been interpreted for the late Holocene lake phase, which likely reflect the response of the basin to changes in fluvial dynamics, climate, and human-landscape interactions. The data produced from this research will serve as a reference point for the impacts of large hydropower projects on tropical rivers and their aquatic ecosystems.
EXPLORING CHANNEL AND TOPOGRAPHIC CHARACTERISTICS RELATED TO TECTONIC DEFORMATION IN THE RUHUHU RIVER, TANZANIA
Lake Malawi exhibited an open hydrologic system that was present even during dry, shallow periods prior to 800ka. Following the lake level transition around 700ka, the lake deepened and became more hydrologically closed with the exception of a single outlet, via the Shire River in the southernmost region. The most feasible candidate for an earlier outlet is the current influent and rift-antecedent Ruhuhu River (Ivory et al., 2016). It was hypothesized (Ivory et al., 2016) that an uplift occurred 700-800ka and altered the direction of flow in the river. For a given tectonic uplift, when one side of the tectonic divide rises, the other side is lowered which reduces the relative base level. After the uplift surfaced, the lake deepened until it reached the modern outlet in the Shire River, where it presently drains through the Zambezi River to the Indian Ocean.
Demonstrated by evidence found in the aquatic evolution of Lake Malawi, the present day Ruhuhu River inlet once served as the outlet and connected the rift lake to the Indian ocean (Ivory et al., 2016). By performing analyses on the Ruhuhu River watershed, we can determine if there are tectonic controls impacting the river’s flow behavior. Digital elevation models (DEM) provided by satellite imagery data will be utilized to assess the fluvial patterns and landform characteristics for evidence of tectonic deformation to test the hypothesis that a structural uplift in the Ruhuhu watershed was responsible for the change in Lake Malawi’s hydrology and biodiversity.
STREAM CHANNEL RESPONSES TO INCREASED NONPOINT SOURCE POLLUTION: A SPATIAL ANALYSIS OF THE RED RIVER GORGE WATERSHED
Throughout the state, the Kentucky Division of Water has recognized several watersheds in need of urgent restoration (Figure 1). This status is a result of at least one nonpoint source pollution such as urban runoff, failed septic systems, agriculture, and surface mining. Among this list is the Red River Gorge Watershed, covering ~148 mi^2. Within the drainage area, pathogens introduced by illegal dumping, loss of streamside vegetation, erosion, and runoff from towns, fields, surface mines, and mills threaten public health. KDOW has attributed the poor water quality to sources of increased sedimentation, impairing the aquatic habitat of local headwater tributaries. This project aims to define probable cause of increased sedimentation to unregulated outdoor regulation and other regional land uses as a function of the regional geology. Evident in Figure 2 and Figure 3, most portions of USFS designated trails lie on the more resistant upper Mississippian and Pennsylvanian formations. In Figure 4, however, the trails lying among seemingly resistant strata are actually lying amid a very expansive region characterized by risk of landslides and slope instability. Figure 5 illustrates the regional surface gradient, supporting the risk of slope failures as well as showing the range of elevation the trails actually occupy. In Figure 2, concentrations of barren land and forested regions provide evidence for trail popularity, land use, and stream channel responses to increased sedimentation sources. Where the park is largely accessible, there will be increased impacts of downstream aquatic habitat impairment, sediment production, runoff, and bank destabilization.
OBSERVING POTENTIAL SOURCES AND IMPACTS OF RECREATIONAL ACTIVITY CAUSED SEDIMENTATION IN THE RED RIVER GORGE, KY
Involvement in recreational activities is growing in popularity. In 1999, a national survey revealed that hiking was the most popular form of outdoor recreation engaged by 67% of Americans (Cordell, 1999). In 2012, the outdoor recreation economy grew 5% annually between 2005-2011, a time of economic recession when many industries contracted. The importance of understanding the connection of land use and presence in the environment is increasing as the efforts to preserve forested and wild lands are impacted by encroaching development and rising tourism. Characterized by its geology and sandstone arches, Red River Gorge Geological Area is internationally recognized for its rock climbing opportunities. Red River Gorge is a National Natural Landmark and Historic District of Daniel Boone National Forest, comprising several congressional designations including a National Wild and Scenic River, National Scenic Byway, and Wilderness. Described by the geographic distribution of geologic formations, the overall rugged terrain and erodible shale and siltstone units support high levels of natural erosion without human disturbance. The purpose of this project was to estimate the bed load sediment storage of point bars along the most popular stretch of the river and be able to make interpretations on the intensity unregulated hiking and camping activities have on the river’s channel stability and erosion.
EXPLORING SHORELINE MIGRATION AND SEDIMENT PLUME AREA ALONG THE OUTLET OF THE RUHUHU RIVER WATERSHED, TANZANIA
Digital elevation data studied in this project was obtained from the NASA Shuttle Radar Topographic Mission (SRTM) database that is distributed by USGS. The highest resolution data for eastern Africa has a 3 arc-second resolution (approx. 90m) and is formatted in 5 deg x 5 deg tiles. The files are georeferenced to the WGS84 datum. Aerial imagery provided by Landsat 4-5TM C-1 Level-1 was displayed in false colour composite to assess the difference in sediment plume pixels from the pixels that made up the rest of Lake Malawi. Eight datasets were acquired from earthexplorer.usgs.gov for images that only had less than 10% cloud cover, acquisition time was during the day, and the data were also limited to summer months. Limiting the data to summer months reduces sources of inaccuracy by removing any seasonal variation of sediment supply within the river. Shoreline data was traced along the eastern margin of the lake for each of the 8 datasets. Sediment plume polygons were mapped over lighter-blue/cyan pixels just beyond the outlet of the river. The polygons were developed this way to ensure maximum control of where the outlet began from the shoreline.
DESCRIBING THE HISTORY AND ORIGIN OF CARBONATE MUD MOUNDS IN SOUTHERN KY
The objective was to determine the history and origin of facies present in a specific carbonate mud mound outcrop in south-central Kentucky. By integrating our knowledge of the regional geological history of the Neoacadian Orogeny, concepts of basement uplift and sea level transgression, and sediment delivery mechanisms that might have existed in the channel at the time of deposition, we could incorporate field observations to determine the origin of the structure. Field observations involved characterizing representative sections of the outcrop, measuring, describing, and photographing the exposed area. Sedimentological, paleontological, and stratigraphic data including lithologies, biogenic structures, fossil fragments, and textures were carefully noted. The field notes were used to develop a representative stratigraphic column.