Browsing by Subject "Playa"
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Item A geological and sedimentological approach to inferring paleoclimate from buried soils within playa fills, southern high plains, Texas(2013-05) Dunne, Gabrielle; Sweet, Dustin E.; Perry, Gad; Parsons, TonyPaleoclimate can be used as a frame work for predicting variability and thresholds of future climate change. The small size and ephemeral nature of inundation make playa wetlands highly sensitive to climatic fluctuations and consequently playas may be able to provide a high resolution terrestrial archive of paleoclimate (Bowen and Johnson, 2012). Holliday et al., (1996) study playa wetlands on the Southern High Plains which are contemporaneous with the Blackwater Draw Formation. The multiple buried soil profiles observed in these playas may extend back 1.6 million years, giving them the potential to be utilized as quaternary climate proxies. Previous studies that use playa lake sediments as a paleoclimate proxy (Bowen and Johnson, 2012, Holliday et al., 2008, Holliday et al., 1996) focus on carbon dating, stratigraphy and analysis of soil profiles. Paleosols preserved in continental settings may be able to provide a long term, continuous climatic record, equal in resolution to marine isotope records (Retallack, 2007), especially under aggradational conditions. Paleosols form at the Earth’s surface in direct contact with the atmosphere, giving them potential as one of the most powerful tools in paleoclimate interpretation (Sheldon and Tabor, 2009). Sheldon and Tabor (2009) summarize whole-rock geochemistry methods to study paleosols in a range of depositional setting. Geochemical ratios and trends observed within major oxides and selected trace elements indicate pedogenic processes in paleosols such as, weathering, leaching and illuviation that are largely climatically driven (Sheldon & Tabor, 2009). Whole-rock geochemistry is interchangeable between paleosols and modern soils allowing comparative studies and inferences to be made regarding the conditions under which paleosols formed (Dreise et al., 2005). The aim of this study is to determine whether the well-established geochemical methods of paleosol analysis as described by Sheldon and Tabor (2009) can be successfully applied to the buried soil profiles of playa wetlands, an area where this type of study has not been previously explored. The objective is to apply these methods to data collected from playa wetlands on the Southern High Plains to; · Assess the degree of weathering within the buried soil profiles. · Assess the grain size distribution within the soil profile. · Assess the variability in buried soil profiles between the playa floor and playa edge. · Asses the variability in buried soil profiles between the eastern and western margins of the Southern High Plains. Comparisons between our finding and the findings of others working in the same area which date their sediments e.g. Bowen and Johnson (2012, Holliday et al., (2008) and Holliday et al., (1996) can be used to determine if the whole-rock geochemistry of playa sediment can be used as a viable proxy for interpreting quaternary climate on the Southern High Plains. Absolute age control of the cores was not assessed; however, we utilize grain size distribution data in comparison with the well-established northerly fining trend observed in the Blackwater Draw Formation to assess reworking and thus, a relatively younger age. Results indicate that buried soils grain size distributions are inconsistent with the range expected within the Blackwater Draw Formation, thus we infer that these paleosols were developed on reworked Blackwater Draw Formation sediments, and thus younger than ~ 40,000 years. Furthermore, C14 dates from nearby playas are used to bolster the grain size comparison trends and suggest that the buried soils analyzed range from ~11-20 ky. The cores were obtained from the center and edge of two playas in Texas, one located in Floyd County, which is on the edge of the eastern escarpment and the other from Bailey County, which is further to the west (Fig 1.0). The cores crossed between two and three buried soil profiles. Samples were obtained from each core at 100 mm intervals for analysis. For each sample data on grain size, major elements (Wt %) and minor elements (PPM) was collected. This data was plotted against depth and trends were analyzed to infer the boundaries of the buried surfaces and different horizons within the buried soil profiles. To determine the degree of weathering within each profile ratios of mobile versus immobile elements were plotted against depth. The pedogenic processes that we attribute as the cause, of the physical and geochemical properties within our core, can be compared with modern pedogenic processes resulting in similar characteristics to infer climatic conditions at the time of their formation.Item AMPHIBIANS OF THE SOUTHERN GREAT PLAINS: HABITAT AND THE IMPACTS OF TEMPERATURE AND pH ON SURVIVAL(2013-05) Kissner, Jessica; Griffis-Kyle, Kerry; McIntyre, Nancy E.; Haukos, David A.; Wallace, Mark C.Global climate change has had an increasing role in the decline of amphibian populations due to direct (e.g. critical temperature thresholds) and indirect (e.g. temperature stress, spreading of disease, and habitat alteration and loss) effects of increasing atmospheric temperature. Due to the complexity of habitats needed to complete all of their life stages, amphibians are subject to stressors through a number of systems (e.g., water quality, climatic characteristics, and terrestrial habitat). Furthermore, habitat currently used by amphibians may become inhospitable due to indirect stressing effects of increased temperatures projected for the Southern Great Plains (SGP). To protect and manage for species at risk, we must first understand their basic community assemblages, distributions, habitat associations, and tolerances. Because little amphibian research has come from northeastern New Mexico, collecting data on these parameters will be a useful tool for future research and management in this area. The objectives of this study were to: (1) examine amphibian species presence, richness, an index of reproductive success, and larval growth in northeastern New Mexico and relate them to site-specific and landscape-level habitat characteristics and (2) identify environmental factors that may jeopardize population persistence in the future. After conducting field work, I determined an additional objective based on the current average high temperature (28.3°C) and pH ranges (4.9 to 9.4) I recorded: (3) to determine the effect of a 5.6°C increase in average summer temperature by 2090 (to 33.9°C) due to climate change on embryo and tadpole survival, the effects of pH 4.9 and 9.4 on embryo and tadpole survival, and the effects of the interactions between pH and temperature on embryo and tadpole survival. Over 2011 and 2012, I sampled each playa wetland 5 times over a 17-day sampling period after precipitation of >2cm using call, visual encounter, egg mass, dip net, and funnel trap surveys to examine the amphibian community. I also collected tadpole measurements throughout development to examine larval growth patterns. Water quality was sampled during each survey, and ArcMap was employed to determine landscape-level habitat features. I sampled 14 playa wetlands in northeastern New Mexico, detecting 7 amphibian species with a maximum species richness per playa of 4. I detected reproduction in 4-6 species (as Pelobatid tadpoles are difficult to identify to species), and larval growth in Anaxyrus cognatus, Pseudacris clarkii, and Pelobatid spp. was exponential up to age 17 days (all p < 0.01). I also documented the first New Mexico state record of Pseudacris clarkii (spotted chorus frog). Although I did not document any statistically significant associations between amphibian species presence, richness, or reproductive success and habitat characteristics, I observed a trend of no P. clarkii reproduction at the acidic sites (4.9-6.9) even though adults were present in playa wetlands with pH 4.9-9.4. Based on my field observations about amphibian natural history from 2011, I hypothesized that increased temperature due to global climate change in 2090 may influence the ability of anurans to survive in pH-stressed playas. I tested these hypotheses in the lab in order to strengthen my field-based inferences. In 2012, I performed a fully-factorial laboratory experiment using the 2011 pH extremes (4.9 and 9.4), 2011 current average temperature (28.3°C), and 2090 projected temperature (33.9°C ), with embryos from 3 pairs of wild-caught P. clarkii. The results of my experiment suggest that P. clarkii cannot successfully reproduce in water with high temperature (33.9°C), regardless of the pH conditions. Furthermore, survival to metamorphosis in acidic conditions (pH 4.9), regardless of temperature, is unlikely, findings consistent with both my field observations and laboratory results. Survival to metamorphosis in basic conditions (pH 9.4) is very low (9%), compared to survival at pH 7 (84 %) that other studies have documented. Based on my findings, an increase in summer temperature of 5.6°C over the next 70 years will likely cause mortality and extirpation of some amphibian species in the Southern Great Plains. My results demonstrate the threat to P. clarkii due to projected climate change and suggest that other amphibian species may also be vulnerable, particularly for anuran populations that are at the edge of their range such as Gastrophryne olivaea, a New Mexico state-endangered species. By combining field and laboratory techniques and coming to a similar conclusion, I have been able to provide conclusions about the effect of temperature and pH on amphibian survival and population persistence.Item Diversity, distribution, and development of the Odonata of the Southern High Plains of Texas(Texas Tech University, 2009-05) Reece, Bryan A.; McIntyre, Nancy E.; Deslippe, Richard J.; Martin, Clyde F.; Mulligan, Kevin; Strauss, Richard E.The diversity, distribution, and developmental patterns of odonates (dragonflies and damselflies; Insecta: Odonata) were examined in the playa system of the Southern High Plains of Texas from 2003-2008. Comparisons were made in these factors between playas surrounded by the two dominant forms of land use (cropland, grassland). Controlled field and lab experiments were performed to examine the causal relationship between environmental variables and growth, development, and survival of larvae of a focal species. Land-use type did have an influence on certain variables, but not consistently or on all variables. Over one hundred new county records were discovered, indicating how little is known about this system. In addition, the dragonfly holdings at the Museum of Texas Tech University were sorted, identified, and compiled, revealing numerous other new county records.Item Examination of polycyclic aromatic hydrocarbons in an urban stormwater system and bioaccumulation in Odonata(2013-08) Heintzman, Lucas; McIntyre, Nancy E.; Carr, Deborah; Griffis-Kyle, KerryPolycyclic aromatic hydrocarbons (PAHs) are toxic organic pollutants produced from combustion processes. Associated with urban runoff they have been detected worldwide in urban wetlands. PAH contaminations in wetlands are known to be influenced by hydrology and environmental factors. Because PAHs and their associated metabolites are carcinogenic, mutagenic, and teratogenic, they pose significant risks to wetland-dependent organisms. Provided meager scientific data on PAHs in playa wetlands, I investigated the occurrence of 16 PAHs within playa surface water samples and tissues of amphibious organisms (Odonata: dragonflies and damselflies, a flagship group of predatory wetland insects) from seven urban playas along a runoff gradient in Lubbock, Texas. PAH detections from surface water samples were highly variable across sites and dates, with naphthalene and pyrene occurring most often in water samples. Adult Odonata PAH detections were also variable but significantly different from corresponding surface water samples (suggesting bioaccumulation rather than passive chemical exposure), with naphthalene and fluoranthene occurring most often. The number of specific PAH compound detections was significantly associated with percent impervious surface within 300 m of a playa, but not with gradient position or number of inflows. Therefore, results indicate that for urban playas of Lubbock, land-use factors are more important in determining PAH contamination than hydrologic factors.Item Implementing conjugate gradients with incomplete Cholesky preconditioning in playa(2012-12) Kennedy, Kimberly R; Long, Kevin; Howle, Victoria E.; Juan, LourdesIn computational sciences, solving an immensely large system of equa- tions is a commonly recurring problem. One of the most effective iterative solvers used for these systems is the method of Conjugate Gradients (CG). CG solves the system Ax = b where A is a NxN symmetric positive definite (SPD), b is a known vector, and x is the unknown vector that is the solution of the mentioned system. There is a version of CG that is used to solve non-symmetric nonsingular matrices but it involves transforming the system Ax = b into AT Ax = A^Tb. Though CG can converge within N iterations in exact arithmetic, it can be vastly improved when a preconditioner is applied. There are several preconditioners that one can use for CG. However, Incomplete Cholesky factorization () was the preconditioner used in this research thus it will be the the primary focus. The implementation of both CG and Incomplete Cholesky Conjugate Gradients (ICCG) can vary in complexity depending on the software used to formulate the code. In Playa, the solver and preconditioners are abstracted so that the end user is able to use a general method or specific method for solving their problem. However, the implementation of ICCG relied on another subpackage Ifpack for the creation of the preconditioners which led to several test matrices having bad preconditioners.Item Simulation of unsaturated flow and heat transport within playa soils(2012-12) Pavur, Robert; Rainwater, Ken; Zartman, Richard E.; Stovall, Jeff N.; Gitz, DennisThe primary objective in this research was to use the observed data and an appropriate unsaturated flow model to estimate the amount of water that can pass the root zone and eventually recharge the Ogallala aquifer for particular playas following specific inundation periods. The first step in approaching this challenge was to screen the field data collected by the playa instrument stations. This step was necessary to determine which parts of the data set provided complete description of the necessary field conditions. The second step was to select a software package that employed input parameters available in this research project either through collected field data or previous study results. Third, the available input parameters were provided to the model, and calibration of the model was performed. Most input parameters were determined with relative ease while others presented difficult challenges, which indicated future research topics. Finally, the modeled results were produced to provide estimates of potential recharge.Item Spatial distribution and morphology of sediments on the Texas Southern High Plains, USA Playa Wetlands(2010-12) Villarreal, Carlos J.; Zartman, Richard E.; Hernandez, Annette; Hudnall, Wayne H.; Gitz, DennisPlaya wetlands are unique geomorphic features on the Southern High Plains of the United States and serve as major recharge sites for the Ogallala aquifer. This study was conducted to evaluate outerbasin cropping system influence on sedimentation within playas. Six playas, three cropland and three rangeland outerbasin watersheds, were selected for the research. Twenty-five soil core samples were collected from each playa using the spoke-wheel design. Samples were taken to Texas Tech University and processed for soil color and particle size distribution analysis. Watershed management was an important aspect influencing the degree of sedimentation in playa wetlands. Sediment depth patterns suggested uneven distribution across the playa basins. Watershed drainage networks and topographic characteristics may have influenced spatial distribution. Measured sediment depth did not vary between land uses, but the cropland playas accumulated more sediments (greater volume) than the playas surrounded by rangeland. Soil color evaluation proved to be an adequate parameter to distinguish historically deposited sediments from the pre-settler sediments. The surface sediment soil color was predominately 10YR 3/2 (very-dark, grayish brown) for the Briscoe and Swisher County playas and 10YR 3/1 (very-dark gray) for the Floyd County playas. Spatial distribution of sediments could be used to evaluate outerbasin management practices.Item Surface and subsurface flow relationships to Ogallala aquifer recharge on the Southern High Plains of Texas(Texas Tech University, 2008-12) Netthisinghe, Annesly; Hudnall, Wayne H.; Mulligan, Kevin; Rainwater, Ken; Zartman, Richard E.; Thompson, Thomas L.Playa lakes, the common geomorphic features on the Southern High Plains, are important sites for Ogallala aquifer recharge. Playas are closed depressions on the landscape that collect surface runoff from the surrounding area. Water in playas is lost through evaporation, evapotranspiration and recharge. Thus, playa watershed characteristics, playa morphology and playa basin soil characteristics become important considerations of playa hydrology. Understanding the playa hydrology is imperative to develop playa management decision support tools to enhance recharge. This research focused on the surface and sub-surface hydrology of playa basins. Four playas on the Texas High Plains with grassland outer basins were studied. Three of them were formed in geographic areas in which the surrounding soils are fine, and the other one was surrounded by loamy soils. Playas studied ranged from 7 to 12 ha. in size and were 9 to 18 meters deep within the landscapes. Playa floors were 0.5 to 0.75 m below the annulus. Playa watersheds were as large as 6.5 km2 and had drainage channel inputs measuring up to 18.5 km long at 1% contributing watershed area. Playas formed from fine sediment areas had extensive surface drainage networks with high drainage density as compared to the one formed from loamy sediments. Sedimentation from drainage channels impacted the typical playa structure. Erosional and depositional effects of drainage deformed the playa annulus to a more flat structure. This structural change in playas increased the surface area and the potential for water evaporation. Playa basin soils were indicative of the hydrological processes. Soil morphological features such as gleying and pedogenic carbonate distribution were self explanatory for the water inundation and playa recharge. Clayey playa floor soils were noncalcareous, indicative of flushing carbonates from the profiles by the recharging waters. Slickensides developed within the deep playa floor soils similarly illustrated the deep water percolation. Playa annulus soils were coarse in texture as compared to the playa floor soils. Redoximorphic features appearing in playa annulus soils provided evidence of either extended hydroperiods in playa annulus areas and/or the effect of lateral water movement from the playa floor. Few drainage input channels flowing on low relief landscapes could explain the non ponding nature of some playas. Absence of redoximorphic features in those playa floor soils suggests similar non-ponding hydrologic history. Noncalcareous playa floor soils at the drainage input zone is consistent with the recharge through this type of playas. High intensity rainfall events, soil stratification, and permeability contrasts, along and slope of playa basins suggest potential through-flow for these playas. Variability in earth conductivity, as measured by electromagnetic induction (EMI), was an effective tool to diagnose the through-flow areas. Spatial variability patterns of soil apparent electrical conductivity refined the focus areas for potential through-flow within the playa basins. Pedological evidence identified the soil textural contrasts of through-flow. Depending on the depth to sand lens, soil ECa vertical heterogeneity as defined by the profile ratio reflected specific signatures for potential through-flow areas. The profile ratio proved to be an effective indicator to identify the through-flow areas within the playa basins. This research proposes that through-flow in playa basins has the potential to be a significant source of recharge. Flow verification and assessment,as a source of recharge is still needed. Electromagnetic induction in combination with pedological analysis and Geographic Information Systems can be a powerful through-flow analysis tool.