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Sample records for municipio playa colectadas

  1. Ecology of playa lakes

    USGS Publications Warehouse

    Haukos, David A.; Smith, Loren M.

    1992-01-01

    Between 25,000 and 30,000 playa lakes are in the playa lakes region of the southern high plains (Fig. 1). Most playas are in west Texas (about 20,000), and fewer, in New Mexico, Oklahoma, Kansas, and Colorado. The playa lakes region is one of the most intensively cultivated areas of North America. Dominant crops range from cotton in southern areas to cereal grains in the north. Therefore, most of the native short-grass prairie is gone, replaced by crops and, recently, grasses of the Conservation Reserve Program. Playas are the predominant wetlands and major wildlife habitat of the region.More than 115 bird species, including 20 species of waterfowl, and 10 mammal species have been documented in playas. Waterfowl nest in the area, producing up to 250,000 ducklings in wetter years. Dominant breeding and nesting species are mallards and blue-winged teals. During the very protracted breeding season, birds hatch from April through August. Several million shorebirds and waterfowl migrate through the area each spring and fall. More than 400,000 sandhill cranes migrate through and winter in the region, concentrating primarily on the larger saline lakes in the southern portion of the playa lakes region.The primary importance of the playa lakes region to waterfowl is as a wintering area. Wintering waterfowl populations in the playa lakes region range from 1 to 3 million birds, depending on fall precipitation patterns that determine the number of flooded playas. The most common wintering ducks are mallards, northern pintails, green-winged teals, and American wigeons. About 500,000 Canada geese and 100,000 lesser snow geese winter in the playa lakes region, and numbers of geese have increased annually since the early 1980’s. This chapter describes the physiography and ecology of playa lakes and their attributes that benefit waterfowl.

  2. Interstitial brines in playa sediments

    USGS Publications Warehouse

    Jones, B.F.; Van Denburgh, A.S.; Truesdell, A.H.; Rettig, S.L.

    1969-01-01

    Study of several closed drainages in the Great Basin has shown that the interstitial solutions of shallow, fine-grained playa deposits store a large quantity of dissolved solids and are often more concentrated than associated lakes and ponds, except in peripheral zones of stream or ground-water inflow. These interstitial fluids, when compared with local runoff, impoundments, or spring waters, commonly have a distinctive ionic composition which sometimes cannot be explained by either simple mixing of surface and subsurface inflow or by evaporative concentration. At Abert Lake, Oregon, the interstitial solute concentrations increased with depth to values as much as five times greater than the lake, except where springs indicate significant ground-water input. Where Na+, Cl, and CO2 species constitute more than 90% of the solutes, Na+ Cl- ratios in the lake water are lower than in interstitial solutions of bottom cores and higher than in playa fluids. At the same time, Na+ K+ ratios are highest in the fluids of lake bottom muds and lowest in playa interstitials. In deeper playa profiles, interstitial Na+ Cl- tended to decrease with depth (5 ft. maximum). In the Abert Lake area, as in other parts of the western Great Basin, Na+ Cl- ratios are indicative of total CO2 in solution and the effects of organic decay in surficial sediments. These ratios, coupled with data on silica and bulk density, show that higher PCO2 accompanying decay promotes silicate dissolution and hydrogen ion exchange, stripping alkalis from sediment which had preferentially adsorbed K+ when entering the lake. On subsequent loss of pore fluid in the playa regime, silica initially released to solution in the lake environment is readsorbed on dissolution products. ?? 1969.

  3. Astronomy at Nabta Playa, Southern Egypt

    NASA Astrophysics Data System (ADS)

    McKim Malville, J.

    Nabta Playa may contain the oldest human-made features with astronomical alignments in Egypt. In the Late and Terminal Neolithic (7,500-5,400 BP), nomadic pastoralists built a ceremonial center on the western shore of Nabta Playa, consisting of some 30 complex megalithic structures, stone circles, and lines of megaliths crossing the playa. The megaliths may once have aligned with Arcturus, the Belt of Orion, Sirius, and α Cen. Reorientations of the northern set of megaliths suggest a response to precession. Elaborate burials at the nearby cemetery at Gebel Ramlah indicate the nomads consisted of Mediterranean and sub-Saharan populations with little social stratification.

  4. Microbial Signatures In Sulfate-Rich Playas

    NASA Astrophysics Data System (ADS)

    Glamoclija, M.; Steele, A.; Starke, V.; Zeidan, M.; Potochniak, S.; Sirisena, K.; Widanagamage, I. H.

    2016-05-01

    Microbes that live in playas represent organisms able to cope with transient environments, ranging from fresh to hyper-saline water settings and from wet to dry. We will try to identify mineral and chemical signatures of their presence.

  5. Dynamics of salt playa polygons

    NASA Astrophysics Data System (ADS)

    Goehring, L.; Fourrière, A.

    2014-12-01

    In natural salt playa or in evaporation pools for the salt extraction industry, one can sometimes see surprising regular structures formed by ridges of salt. These ridges connect together to form a self-organized network of polygons one to two meters in diameter, which we call salt polygons. Here we propose a mechanism based on porous media convection of salty water in soil to explain the formation and the scaling of the salt polygons. Surface evaporation causes a steady upward flow of salty water, which can cause precipitation near the surface. A vertical salt gradient then builds up in the porous soil, with heavy salt-saturated water lying over the less salty source water. This can drive convection when a threshold is reached, given by a critical Rayleigh number of about 7. We suggest that the salt polygons are the surface expression of the porous medium convection, with salt crystallizing along the positions of the convective downwellings. To study this instability directly, we developed a 2D analogue experiment using a Hele-Shaw cell filled with a porous medium saturated with a salt solution and heated from above. We perform a linear stability analysis of this system, and find that it is unstable to convection, with a most unstable wavelength that is set by a balance between salt diffusion and water evaporation. The Rayleigh number in our experiment is controlled by the particle size of our model soil, and the evaporation rate. We obtain results that scale with the observation of natural salt polygons. Using dye, we observe the convective movement of salty water and find downwelling convective plumes underneath the spots where surface salt ridges form, as shown in the attached figure.

  6. The restless rock of Racetrack Playa

    NASA Astrophysics Data System (ADS)

    Jackson, Brian; Lorenz, Ralph; Norris, Richard

    2015-07-01

    Tucked away in California's Death Valley National Park, the flat basin known as Racetrack Playa is littered with stones that seem to migrate across the landscape. But how do they do it? Brian Jackson describes how he and collaborators Ralph Lorenz and Richard Norris solved a long-standing mystery.

  7. Salt Playas of the Bolivian Altiplano

    NASA Technical Reports Server (NTRS)

    2003-01-01

    In the high plateau of southwestern Bolivia, two large salt deserts, or playas, are located between the eastern and western Andes. The Salar de Uyuni is the largest and highest playa in the world, encompassing an area of more than 9000 square kilometers and situated more than 3600 meters above sea level. It is separated by a range of hills from its smaller neighbor to the north, the Salar de Coipasa. During the Pleistocene the climate of the region was wetter and the entire area was covered by a massive lake. As the waters slowly dried, abundant dissolved minerals were left behind to form the playas. The salt pans are now excellent indicators of rainfall fluctuations within the region and are also important sites for the study of paleoclimatology.

    These two image pairs from the Multi-angle Imaging SpectroRadiometer (MISR)depict the playas on January 16, 2002 and January 3, 2003. At this time of year the wet season has already begun, and the Salar de Coipaso is usually at least partially flooded. Data from these two dates were processed identically to preserve relative variations in brightness between them. Varying degrees of surface moisture around the two playas are illustrated by the different display techniques of the right and left-hand panels.

    At left are two false-color views acquired by MISR's nadir camera. Data from the near-infrared, green and blue bands are displayed as red, green and blue. This spectral display causes bright, wet surfaces to appear blue-green because water selectively absorbs longer wavelengths such as near-infrared. Significantly more standing water is present in the Salar de Coipaso in 2002 than in 2003. However, a stronger signal at the near-infrared band on the 2003 date, which causes the overall hue in the 2003 image to be redder than 2002, suggests an increase in photosynthetic activity (plant growth) at the 2003 date compared with one year earlier.

    The right-hand panels were created using only red band data, and are

  8. Grass buffers for playas in agricultural landscapes: A literature synthesis

    USGS Publications Warehouse

    Melcher, Cynthia P.; Skagen, Susan K.

    2005-01-01

    Future research should entail multiple-scale approaches at regional, wetland-complex, and individual watershed scales. Information needs include direct measures of buffer effectiveness in ‘real-world’ systems, refinement and field tests of buffer-effectiveness models, how buffers may affect floral and faunal communities of playas, and basic ecological information on playa function and playa wildlife ecology. Understanding how wildlife communities respond to patch size and habitat fragmentation is crucial for addressing questions regarding habitat quality of grass buffers in playa systems.

  9. Physical loss and modification of Southern Great Plains playas.

    PubMed

    Johnson, Lacrecia A; Haukos, David A; Smith, Loren M; McMurry, Scott T

    2012-12-15

    Playas are the primary wetland system in the Southern Great Plains (SGP) of North America providing critical stopover habitats for migratory birds in the Western Hemisphere. Collectively, these wetlands form the keystone ecosystem in this region supporting biodiversity for North America and provide habitat for native plants and animals that are essential for maintenance of international biological diversity along with other local and regional ecological services. Large-scale landscape changes in this region, primarily as a result of agriculturally-based anthropogenic impacts, threaten playas with functional loss and physical extinction. These impacts are not considered in current estimates of the number of extant functional playas, leading to biased estimates by groups or agencies extrapolating research or monitoring results, conducting conservation planning, and modeling impacts of future climate change. Using a combination of stochastic and empirical data, we identified impacts to playas and playa watersheds and quantified the extent and rate of these impacts relative to physical loss. Only 0.2% of playas had no wetland or watershed modification and we conservatively estimate that 17% of playas recently existing on the landscape no longer are represented by an apparent depression. With the inclusion of sediment volume estimates where ≥100% of the volume of original differentiated playa soil has been filled, 60% or 16,855 playas have been physically lost from the SGP despite a continued presence of a depression. Data also show that small playas are being lost more rapidly than larger ones; the average size (±SE) of extant playas has increased from 7.5 ± 0.47 to 8.5 ± 0.55 ha. The reduced ecological condition of 95.3% of playas remaining on the landscape exceeds historical predictions of a maximum 85% of playas ever being modified. Given the results of this study these changes can now be accounted for, resulting in more informed management and

  10. Physical loss and modification of Southern Great Plains playas.

    PubMed

    Johnson, Lacrecia A; Haukos, David A; Smith, Loren M; McMurry, Scott T

    2012-12-15

    Playas are the primary wetland system in the Southern Great Plains (SGP) of North America providing critical stopover habitats for migratory birds in the Western Hemisphere. Collectively, these wetlands form the keystone ecosystem in this region supporting biodiversity for North America and provide habitat for native plants and animals that are essential for maintenance of international biological diversity along with other local and regional ecological services. Large-scale landscape changes in this region, primarily as a result of agriculturally-based anthropogenic impacts, threaten playas with functional loss and physical extinction. These impacts are not considered in current estimates of the number of extant functional playas, leading to biased estimates by groups or agencies extrapolating research or monitoring results, conducting conservation planning, and modeling impacts of future climate change. Using a combination of stochastic and empirical data, we identified impacts to playas and playa watersheds and quantified the extent and rate of these impacts relative to physical loss. Only 0.2% of playas had no wetland or watershed modification and we conservatively estimate that 17% of playas recently existing on the landscape no longer are represented by an apparent depression. With the inclusion of sediment volume estimates where ≥100% of the volume of original differentiated playa soil has been filled, 60% or 16,855 playas have been physically lost from the SGP despite a continued presence of a depression. Data also show that small playas are being lost more rapidly than larger ones; the average size (±SE) of extant playas has increased from 7.5 ± 0.47 to 8.5 ± 0.55 ha. The reduced ecological condition of 95.3% of playas remaining on the landscape exceeds historical predictions of a maximum 85% of playas ever being modified. Given the results of this study these changes can now be accounted for, resulting in more informed management and

  11. Topography, surface features, and flooding of Rogers Lake playa, California

    USGS Publications Warehouse

    Dinehart, Randal L.; McPherson, Kelly R.

    1998-01-01

    Rogers Lake is a desert playa used as a military airport for Edwards Air Force Base in the Antelope Valley of southern California. Previous measurements of land subsidence and ground-water levels in the study area indicated that ground-water pumping induced tensional stresses in the playa, which were sporadically relieved through the formation of long cracks. Drying of the sediments beneath the playa also may have accelerated the natural formation of giant desiccation polygons. When water flows across the playa, the cracks erode into fissures of sufficient width and depth to endanger traffic on the playa. Topographic surveys of the playa were made to derive a contour map that would allow examination of erosive flow paths. Crack networks were surveyed in selected areas during 1995 and compared with cracks visible in aerial photographs taken in 1990. Crack networks remained visible in their positions following several inundations of the playa. The density of the crack networks increased in all of the selected areas.

  12. Understanding and constraining global controls on dust emissions from playas

    NASA Astrophysics Data System (ADS)

    Bryant, Robert; Eckardt, Frank; Vickery, Kate; Wiggs, Giles; Hipondoka, Martin; Murray, Jon; Baddock, Matt; Brindley, Helen; King, James; Nield, Jo; Thomas, Dave; Washington, Richard; Haustein, Karsten

    2016-04-01

    Playas are ephemeral, endorheic lake systems that are common in arid regions. They have been identified as both regionally and globally significant sources of mineral dust. Emissions of dust from large playas can therefore impact significantly on regional climate through a range of land/atmosphere interactions. However, not all playas have or will emit dust, and those that do emit dust rarely do so consistently. Thus, global models that target ephemeral lakes at source areas often struggle to model the emission characteristics of the locations accurately. It is clear that our understanding of controls on dust emission from these environments varies at global scales (i.e. relevant to climate models) is poorly understood. Existing research confirms that the potential for dust emission from playas within dryland regions can be extremely varied; large disparities are noted to exist from one playa to another, and significant spatial/temporal heterogeneity has been observed within those playas that do emit dust. Research also shows that dust fluxes from playa surfaces varies vary based on hydrological gradient or ephemeral inflows and may change over time in response to human or climate forcing mechanisms. Consequently, despite the presence of abundant fine sediment and suitable wind conditions, some playas will remain supply limited and will not emit dust as they are either too wet (e.g. via extensive groundwater discharge) not salty enough (e.g. salts have been removed from the surface by groundwater recharge) or there is not a sufficient supply of sand (coarse particles) on or at the upwind edge of the playa surface to cause dust emission. Other playas (e.g. Owens Lake) have emitted dust at a disproportionate (regionally/nationally) significant level seemingly without constraint (becoming effectively transport capacity limited) through optimal combinations of the same factors. Finally, we can also see situations where dust emitting playa systems flip between supply

  13. Evaporation from groundwater discharge playas, Estancia Basin, central New Mexico

    USGS Publications Warehouse

    Menking, Kirsten M.; Anderson, Roger Y.; Brunsell, Nathaniel A.; Allen, Bruce D.; Ellwein, Amy L.; Loveland, Thomas A.; Hostetler, Steven W.

    2000-01-01

    Bowen ratio meteorological stations have been deployed to measure rates of evaporation from groundwater discharge playas and from an adjacent vegetated bench in the Estancia Basin, in central New Mexico. The playas are remnants of late Pleistocene pluvial Lake Estancia and are discharge areas for groundwater originating as precipitation in the adjacent Manzano Mts. They also accumulate water during local precipitation events. Evaporation is calculated from measured values of net radiation, soil heat flux, atmospheric temperature, and relative humidity. Evaporation rates are strongly dependent on the presence or absence of standing water in the playas, with rates increasing more than 600% after individual rainstorms. Evaporation at site E-12, in the southeastern part of the playa Complex, measured 74 cm over a yearlong period from mid-1997 through mid-1998. This value compares favorably to earlier estimates from northern Estancia playas, but is nearly three times greater than evaporation at a similar playa in western Utah. Differences in geographical position, salt crust composition, and physical properties may explain some of the difference in evaporation rates in these two geographic regions.

  14. Deposition of playa windblown dust over geologic time scales

    NASA Astrophysics Data System (ADS)

    Pelletier, Jon D.; Cook, Joseph P.

    2005-11-01

    Thick eolian deposits are commonly observed beneath desert pavements downwind of dust-emitting playas. These deposits play an important role in piedmont-surface evolution, controlling surface hydrologic conductivity and rates of pedogenesis. To better understand the factors controlling the spatial distribution of eolian deposition, we developed a numerical model that treats deposition from spatially distributed playa sources using analytic point-source solutions for deposition from a Gaussian plume. The model also accounts for complex downwind topography. As a test case, model predictions were compared to eolian deposit thicknesses on Eagle Mountain piedmont, southern Amargosa Valley, California, which receives dust from nearby Franklin Lake playa. The close relationship between the model predictions and mapped thicknesses suggests that eolian transport and deposition can be modeled from basin to regional scales within this framework. These results have important implications for hydrologic, pedogenic, and air-quality problems.

  15. Dynamics of playa lakes in the Texas High Plains

    NASA Technical Reports Server (NTRS)

    Reeves, C. C., Jr. (Principal Investigator)

    1972-01-01

    The author has identified the following significant results. Three small playa lake basins on the southern High Plains, Texas, have been examined by geologists, pedologists, hydrologists, and botanists to establish ground truth for correlation with ERTS-1 imagery. Although the sites are recognizable, details of the three playa basins are too small, at present resolution, to be accurately determined by the available MSS imagery. However, a fourth study site, consisting of a dual playa complex approximately 5 miles long in a basin of 9 square miles, does resolve available imagery allowing accurate measurement of water fluctuations and water depth. Of the available MSS imagery, Band 5 is the most usable. Definition of Band 4 is less due to reduced tonal contrast. The greatest tonal contrast appears on Band 6 and Band 7 between dry land and water areas. Band 6 is particularly good for defining large water areas, Band 7 being best for small lake basins, and Band 5 for growing fields.

  16. Investigation of a playa lake bed using geophysical electrical methods

    NASA Astrophysics Data System (ADS)

    Herrmenn, M.; Gurrola, H.; William, R.; Montalvo, R.; Horton, S.; Homberg, J.; Allen, T.; Bribiesca, E.; Lindsey, C.; Anderson, H.; Seshadri, S.; Manns, S.; Hassan, A.; Loren, C.

    2005-12-01

    The 2005 undergraduate applied geophysical class of Texas Tech University conducted a geophysical survey of a playa lake approximately 10 miles northwest of Lubbock Texas. The playa lake is primarily used as grazing land for two llamas and a hand full of sheep, and has been recently used as a dump for broken down sheds and barrels. Our goal was to model the subsurface of the transition from the playa to plains geology and investigate the possible contamination, of the soil and the data, by the metal dumped at the surface. We conducted our survey with and EM31 and homemade D.C. resistivity and SP equipment that allowed students to grasp the theories more clearly. SP readings were collected using clay pots constructed from terracotta pots and copper tubing purchased at the local hardware store and voltage measurements collected with handle held multi-meters. D.C. resistivity data were collected in a dipole-dipole array using 20 nine volt batteries connected in series with a large enough variable resistor and amp meter to regulate steady current flow. A multi meter was used to collect voltage readings. Wenner array data were collected using a home-made multi-filament cable connected switch box to allow a central user to regulate current and take voltage reading. A map of conductivity produced from a 10 m of EM31 reading show that conductivity anomalies mirror topography. The SP profiles show high values in the playa lake that drop off as we move from the clay rich lake bed to normal grassland. Analysis of both the Dipole-Dipole and Wenner array data support a model with 3 flat layers increasing in resistivity with depth. It appears that these remain flat passing beneath the playa and the playa is eroded into these layers.

  17. Comments on Racetrack playa: Rocks moved by wind alone

    NASA Astrophysics Data System (ADS)

    Sanz-Montero, M. E.; Cabestrero, Ó.; Rodríguez-Aranda, J. P.

    2016-03-01

    The mechanisms by which rocks move across the beds of playa lakes leaving tracks continue to be debated (Sanz-Montero and Rodríguez-Aranda, 2013; Norris et al., 2014; Sanz-Montero et al., 2015a,b; Baumgardner and Shaffer, 2015; Jones and Hooke, 2015). In this regard, the article by Jones and Hooke (Aeolian Research 19, 2015) is particularly interesting since it provides a description of these mechanisms by R. Jones who, during a storm event in 1972, was probably the first person to witness movement of rocks. The dominant meteorological conditions described by Jones during the period when the tracks were formed are, significantly, rather similar to those previously described by Clements (1952) at Little Bonnie Claire Playa (Nevada, USA). The storm conditions referred to in the article also coincide with the observations, measurements and deductions made by Sanz-Montero and Rodríguez-Aranda (2013) and Sanz-Montero et al. (2015a,b) at Altillo Chica playa lake, Central Spain. Furthermore, we were able to carry out an on-site analysis of the sedimentary structures at Racetrack playa in June 2015, allowing us to verify the similarity of the features present at both sites. Together with the important role played by gusty winds in the formation of the tracks, all the above mentioned studies point to the presence of a thin veneer of water, just a few millimeters deep, in the area of the playa lake where the rock movements occur. However, Jones and Hooke (2015) disregard the force exerted by moving water and analyze the coefficient of friction assuming that the rocks are moved by wind alone. We offer an alternative explanation for the movement of rocks both at Racetrack and Altillo Chica playa lake which considers not only the wind but also the role played by moving water in conjunction with other parameters which modify the erosion thresholds (rocks acting as obstacles) and reduce friction (benthic microorganisms).

  18. Geomorphic and hydrologic controls of dust emissions during drought from Yellow Lake playa, West Texas, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research on the factors that control dust emissions from playas has revealed a number of complex geomorphic and hydrologic factors, yet there are few measurements of dust emissions from playas during drought or low-emission seasons. Deflation of Yellow Lake, a saline playa in West Texas, produces sa...

  19. Estimating Recharge through Playa Lakes to the Southern High Plains Aquifer

    NASA Astrophysics Data System (ADS)

    Rainwater, K.; Ganesan, G.; Gitz, D.; Zartman, R.; Hudnall, W.; Smith, L.

    2009-12-01

    In the Southern High Plains of Texas, it is accepted that focused recharge to the High Plains Aquifer (locally known as the Ogallala) occurs through over 20,000 playa lakes, which are local depressions that collect storm runoff. The amount and rate of recharge is not precisely known, and the impact of the land use surrounding each playa lake on the amount of runoff has not been quantified. Each playa exists within its own watershed, and many of those are cultivated, while others are surrounded by native grassland or conservation reserve program (CRP) lands. The amount of sediments entering most playas following cultivation has been substantial, but whether this erosion has had a harmful influence on recharge is unknown. Changing recharge rates can also impact the playa ecosystems that are pivotal to many types of local wildlife. Improved understanding of playa recharge is necessary for proper management strategies for long-term survivability of the Ogallala aquifer. Over the last four years, the research team selected and instrumented 30 playas (10 counties, one cropland playa, one native grassland playa, one CRP playa in each) for observation of their water budgets. To quantify recharge in each playa, data collection includes sufficient weather instrumentation to determine local precipitation and free water evaporation, as well as water level monitoring in the playa lake. The depth/area/volume relationship for each playa was developed by local GPS surveying. Between rainfall/runoff events, seepage through the playa bottom is calculated as the difference between the change in the volume of water stored in the playa and the calculated free water evaporation. The research team hopes to keep the instrumentation operational for as long as possible, hopefully several years, to observe enough inundation events to characterize a range of behaviors in the different playa basins. In this presentation, initial water budget analyses for several of the initially instrumented

  20. Dust emission from wet and dry playas in the Mojave Desert, USA

    USGS Publications Warehouse

    Reynolds, R.L.; Yount, J.C.; Reheis, M.; Goldstein, H.; Chavez, P.; Fulton, R.; Whitney, J.; Fuller, C.; Forester, R.M.

    2007-01-01

    The interactions between playa hydrology and playa-surface sediments are important factors that control the type and amount of dust emitted from playas as a result of wind erosion. The production of evaporite minerals during evaporative loss of near-surface ground water results in both the creation and maintenance of several centimeters or more of loose sediment on and near the surfaces of wet playas. Observations that characterize the texture, mineralogic composition and hardness of playa surfaces at Franklin Lake, Soda Lake and West Cronese Lake playas in the Mojave Desert (California), along with imaging of dust emission using automated digital photography, indicate that these kinds of surface sediment are highly susceptible to dust emission. The surfaces of wet playas are dynamic - surface texture and sediment availability to wind erosion change rapidly, primarily in response to fluctuations in water-table depth, rainfall and rates of evaporation. In contrast, dry playas are characterized by ground water at depth. Consequently, dry playas commonly have hard surfaces that produce little or no dust if undisturbed except for transient silt and clay deposited on surfaces by wind and water. Although not the dominant type of global dust, salt-rich dusts from wet playas may be important with respect to radiative properties of dust plumes, atmospheric chemistry, windborne nutrients and human health.

  1. Geohydrology and evapotranspiration at Franklin Lake Playa, Inyo County, California

    SciTech Connect

    1990-12-01

    Franklin Lake playa is one of the principal discharge areas of the Furnace Creek Ranch-Alkali Flat ground-water-flow system in southern Nevada and adjacent California. Yucca Mountain, Nevada, located within this flow system, is being evaluated by the US Department of Energy to determine its suitability as a potential site for a high-level nuclear-waste repository. To assist the US Department of Energy with its evaluation of the Yucca Mountain site, the US Geological Survey developed a parameter-estimation model of the Furnace Creek Ranch-Alkali Flat ground-water-flow system. Results from sensitivity analyses made using the parameter-estimation model indicated that simulated rates of evapotranspiration at Franklin Lake playa had the largest effect on the calculation of transmissivity values at Yucca Mountain of all the model-boundary conditions and, therefore, that evapotranspiration required careful definition. 72 refs., 59 figs., 26 tab.

  2. Geohydrology and evapotranspiration at Franklin Lake playa, Inyo County, California

    SciTech Connect

    Czarnecki, J.B.

    1997-12-31

    Franklin Lake playa is one of the principal discharge areas of the Furnace Creek Ranch-Alkali Flat ground-water-flow system in southern Nevada and adjacent California. Yucca Mountain, Nevada, located within this flow system, is being evaluated by the US Department of Energy to determine its suitability as a potential site for a high-level nuclear-waste repository. To assist the U.S. Department of Energy with its evaluation of the Yucca Mountain site, the US Geological Survey developed a parameter-estimation model of the Furnace Creek Ranch-Alkali Flat ground-water-flow system. Results from sensitivity analyses made using the parameter-estimation model indicated that simulated rates of evapotranspiration at Franklin Lake playa had the largest effect on the calculation of transmissivity values at Yucca Mountain of all the model-boundary conditions and, therefore, that evapotranspiration required careful definition.

  3. Bacterial succession within an ephemeral hypereutrophic mojave desert playa lake

    USGS Publications Warehouse

    Navarro, J.B.; Moser, D.P.; Flores, A.; Ross, C.; Rosen, Michael R.; Dong, H.; Zhang, G.; Hedlund, B.P.

    2009-01-01

    Ephemerally wet playas are conspicuous features of arid landscapes worldwide; however, they have not been well studied as habitats for microorganisms. We tracked the geochemistry and microbial community in Silver Lake playa, California, over one flooding/desiccation cycle following the unusually wet winter of 2004-2005. Over the course of the study, total dissolved solids increased by 10-fold and pH increased by nearly one unit. As the lake contracted and temperatures increased over the summer, a moderately dense planktonic population of 1 ?????106 cells ml-1 of culturable heterotrophs was replaced by a dense population of more than 1????????109 cells ml-1, which appears to be the highest concentration of culturable planktonic heterotrophs reported in any natural aquatic ecosystem. This correlated with a dramatic depletion of nitrate as well as changes in the microbial community, as assessed by small subunit ribosomal RNA gene sequencing of bacterial isolates and uncultivated clones. Isolates from the early-phase flooded playa were primarily Actinobacteria, Firmicutes, and Bacteroidetes, yet clone libraries were dominated by Betaproteobacteria and yet uncultivated Actinobacteria. Isolates from the late-flooded phase ecosystem were predominantly Proteobacteria, particularly alkalitolerant isolates of Rhodobaca, Porphyrobacter, Hydrogenophaga, Alishwenella, and relatives of Thauera; however, clone libraries were composed almost entirely of Synechococcus (Cyanobacteria). A sample taken after the playa surface was completely desiccated contained diverse culturable Actinobacteria typically isolated from soils. In total, 205 isolates and 166 clones represented 82 and 44 species-level groups, respectively, including a wide diversity of Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Gemmatimonadetes, Acidobacteria, and Cyanobacteria. ?? 2008 Springer Science+Business Media, LLC.

  4. Site study plan for Playa investigations, Deaf Smith County, Texas: Salt Repository Project

    SciTech Connect

    Not Available

    1987-04-02

    This plan defines the purpose and objectives of the Playa Investigation Study, presents a plan of work to provide the information necessary to resolve issues, and discusses the rationale for test method selection. The required information will be obtained from existing well drilling records, describing and testing of soil and rock samples recovered from project test holes, geophysical well logs, seismic surveys, and shallow test pits excavated at ground surface. There have been numerous, often conflicting, theories presented to explain the origin(s) of the playas of the Texas High Plains. The primary purpose of this study is to establish if existing playas and playa alignments are related to deeper subsurface structure, such as faulting or salt dissolution, the potential for future playa development, and the significance of existing and/or future playas on siting a repository in Deaf Smith County, Texas. 11 refs.

  5. Development rates of Late Quaternary soils, Silver Lake Playa, California

    USGS Publications Warehouse

    Reheis, M.C.; Harden, J.W.; McFadden, L.D.; Shroba, R.R.

    1989-01-01

    Soils formed on alluvial fan deposits that range in age from about 35 000 to 200 yr BP near Silver Lake playa in the Mojave Desert permit study of the rates of soil development in an arid, hyperthermic climate. Field-described properties of soils were quantified and analyzed using a soil development index that combines properties and horizon thicknesses. Pedogenic CaCO3 (as indicated by color), pH increase, and dry consistence appear to change with age at linear rates, whereas rubification appears to change at a logarithmic rate. The linear rates are best attributed to the progressive accumulation of CaCO3- and salt-rich eolian dust derived from the playa and other mnore distant sources. The total-texture values of soils on fans older than 10 000 yr BP are similar, which suggests that playas in this area may have been wet enough to restrict the availability of fines from these sources for many thousands of years prior to 10 000 yr BP. Equations derived from regressions of soil age and properties can be used to estimate ages of undated, lithologically similar deposits in similar climates and geomorphic settings. -from Authors

  6. Recharge Rates and Chemistry Beneath Playas of the High Plains Aquifer - A Literature Review and Synthesis

    USGS Publications Warehouse

    Gurdak, Jason J.; Roe, Cassia D.

    2009-01-01

    Playas are ephemeral, closed-basin wetlands that are important zones of recharge to the High Plains (or Ogallala) aquifer and critical habitat for birds and other wildlife in the otherwise semiarid, shortgrass prairie and agricultural landscape. The ephemeral nature of playas, low regional recharge rates, and a strong reliance on ground water from the High Plains aquifer has prompted many questions regarding the contribution of recharge from playas to the regional aquifer. To address these questions and concerns, the U.S. Geological Survey, in cooperation with the Playa Lakes Joint Venture, present a review and synthesis of the more than 175 publications about recharge rates and chemistry beneath playas and interplaya settings. Although a number of questions remain regarding the controls on recharge rates and chemistry beneath playas, the results from most published studies indicate that recharge rates beneath playas are substantially (1 to 2 orders of magnitude) higher than recharge rates beneath interplaya settings. The synthesis presented here supports the conceptual model that playas are important zones of recharge to the High Plains aquifer and are not strictly evaporative pans. The major findings of this synthesis yield science-based implications for the protection and management of playas and ground-water resources of the High Plains aquifer and directions for future research.

  7. Macropolygon morphology, development, and classification on North Panamint and Eureka playas, Death Valley National Park CA

    USGS Publications Warehouse

    Messina, P.; Stoffer, P.; Smith, W.C.

    2005-01-01

    Panamint and Eureka playas, both located within Death Valley National Park, exhibit a host of surficial features including fissures, pits, mounds, and plant-covered ridges, representing topographic highs and lows that vary up to 2 m of relief from the playa surface. Aerial photographs reveal that these linear strands often converge to form polygons, ranging in length from several meters to nearly a kilometer. These features stand out in generally dark contrast to the brighter intervening expanse of flat, plant-free, desiccated mud of the typical playa surface. Ground-truth mapping of playa features with differential GPS (Global Positioning System) was conducted in 1999 (North Panamint Valley) and 2002 (Eureka Valley). High-resolution digital maps reveal that both playas possess macropolygons of similar scale and geometry, and that fissures may be categorized into one of two genetic groups: (1) shore-parallel or playa-interior desiccation and shrinkage; and (2) tectonic-induced cracks. Early investigations of these features in Eureka Valley concluded that their origin may have been related to agricultural activity by paleo-Indian communities. Although human artifacts are abundant at each locale, there is no evidence to support the inference that surface features reported on Eureka Playa are anthropogenic in origin. Our assumptions into the genesis of polygons on playas is based on our fortuitous experience of witnessing a fissure in the process of formation on Panamint Playa after a flash flood (May 1999); our observations revealed a paradox that saturation of the upper playa crusts contributes to the establishment of some desiccation features. Follow-up visits to the same feature over 2 yrs' time are a foundation for insight into the evolution and possible longevity of these features. ?? 2005 Elsevier B.V. All rights reserved.

  8. Macropolygon morphology, development, and classification on North Panamint and Eureka playas, Death Valley National Park CA

    NASA Astrophysics Data System (ADS)

    Messina, Paula; Stoffer, Phil; Smith, Ward C.

    2005-12-01

    Panamint and Eureka playas, both located within Death Valley National Park, exhibit a host of surficial features including fissures, pits, mounds, and plant-covered ridges, representing topographic highs and lows that vary up to 2 m of relief from the playa surface. Aerial photographs reveal that these linear strands often converge to form polygons, ranging in length from several meters to nearly a kilometer. These features stand out in generally dark contrast to the brighter intervening expanse of flat, plant-free, desiccated mud of the typical playa surface. Ground-truth mapping of playa features with differential GPS (Global Positioning System) was conducted in 1999 (North Panamint Valley) and 2002 (Eureka Valley). High-resolution digital maps reveal that both playas possess macropolygons of similar scale and geometry, and that fissures may be categorized into one of two genetic groups: (1) shore-parallel or playa-interior desiccation and shrinkage; and (2) tectonic-induced cracks. Early investigations of these features in Eureka Valley concluded that their origin may have been related to agricultural activity by paleo-Indian communities. Although human artifacts are abundant at each locale, there is no evidence to support the inference that surface features reported on Eureka Playa are anthropogenic in origin. Our assumptions into the genesis of polygons on playas is based on our fortuitous experience of witnessing a fissure in the process of formation on Panamint Playa after a flash flood (May 1999); our observations revealed a paradox that saturation of the upper playa crusts contributes to the establishment of some desiccation features. Follow-up visits to the same feature over 2 yrs' time are a foundation for insight into the evolution and possible longevity of these features.

  9. Dynamics of Playa Lakes in the Texas High Plains

    NASA Technical Reports Server (NTRS)

    Reeves, C. C., Jr. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. This project is designed to correlate ERTS-1 satellite imagery signatures with the water balance ecosystem and geology of select playa lake basins in West Texas. The principal work consisted of monitoring the weather instruments, the measurement of water levels and water depths examination of MSS imagery, and measurement of water and mud areas by use of ESIAC (Electronic Satellite Image Analysis Console) at Stanford Research Center, Menlo Park, California. A cost/benefit analysis, comparing the use of ERTS-1 data to more conventionally secured data, revealed that use of ERTS-1 data for such a survey reduces cost from $2.00 to $0.03/square mile.

  10. Magnesite formation in playas: A natural analogue for carbon sequestration

    NASA Astrophysics Data System (ADS)

    Power, Ian; Harrison, Anna; Wilson, Siobhan; Dipple, Gregory; Fallon, Stewart

    2015-04-01

    Non-marine carbonate deposits are of renewed interest as natural analogues for carbon sequestration and storage. Specifically, the sequestration of anthropogenic carbon dioxide (CO2)in Mg-carbonate minerals is being actively investigated as a strategy for reducing greenhouse gas emissions1. In northern British Columbia, hydromagnesite-magnesite playas (hectare-scale) have formed since the last deglaciation, suggesting that these minerals possess a level of stability required for long-term carbon storage2. Quantitative mineralogical and hydrogeochemical data, as well as microscopy and field observations, were used to formulate a comprehensive facies model that describes the depositional environments for the formation of these playas. Over several millennia, there have been transitions from deposition of siliciclastic to subaqueous Ca-Mg-carbonate to subaerial Mg-carbonate sediments3,4. Consequently, a complex assemblage of carbonate minerals is present within the playas including magnesite [MgCO3], the most stable Mg-carbonate for storing CO2. Magnesite precipitation at near-surface temperatures is kinetically inhibited due to the strong hydration of Mg2+ ions in solution5. Thus, understanding the rates of, and controls on, magnesite formation at low temperatures remains a challenge. Magnesite abundances at the surface (1 to 41 wt.%) and at depth (1 to 86 wt.%) within the playas are highly variable4. There is a propensity for hydrated Mg-carbonate minerals to undergo transformation to less hydrated, more stable forms (lansfordite > nesquehonite > dypingite > hydromagnesite)5; however, stable, radiogenic, and clumped isotope6 data as well as electron microscopy demonstrate that magnesite formation is likely dominated by direct precipitation from aqueous solution in the shallow subsurface (~3-10 ° C). An observed variation in magnesite crystal morphology with depth is attributed to different crystal growth mechanisms induced by changes in magnesite saturation state

  11. Simulated natural hydrologic regime of an intermountain playa conservation site

    USGS Publications Warehouse

    Sanderson, J.S.; Kotliar, N.B.; Steingraeber, D.A.; Browne, C.

    2008-01-01

    An intermountain playa wetland preserve in Colorado's San Luis Valley was studied to assess how its current hydrologic function compares to its natural hydrologic regime. Current hydrologic conditions were quantified, and on-site effects of off-site water use were assessed. A water-budget model was developed to simulate an unaltered (i.e., natural) hydrologic regime, and simulated natural conditions were compared to observed conditions. From 1998-2002, observed stream inflows accounted for ??? 80% of total annual water inputs. No ground water discharged to the wetland. Evapotranspiration (ET) accounted for ??? 69% of total annual water loss. Simulated natural conditions differed substantially from current altered conditions with respect to depth, variability, and frequency of flooding. During 1998-2002, observed monthly mean surface-water depth was 65% lower than under simulated natural conditions. Observed monthly variability in water depth range from 129% greater (May) to 100% less (September and October) than simulated. As observed, the wetland dried completely (i.e., was ephemeral) in all years; as simulated, the wetland was ephemeral in two of five years. For the period 1915-2002, the simulated wetland was inundated continuously for as long as 16 years and nine months. The large differences in observed and simulated surface-water dynamics resulted from differences between altered and simulated unaltered stream inflows. The maximum and minimum annual total stream inflows observed from 1998-2005 were 3.1 ?? 106 m3 and 0 m3, respectively, versus 15.5 ?? 106 m3 and 3.2 ?? 106 m3 under simulated natural conditions from 1915-2002. The maximum simulated inflow was 484% greater than observed. These data indicate that the current hydrologic regime of this intermountain playa differs significantly from its natural hydrologic regime, which has important implications for planning and assessing conservation success. ?? 2008, The Society of Wetland Scientists.

  12. Occurrence of cotton herbicides and insecticides in playa lakes of the High Plains of West Texas

    USGS Publications Warehouse

    Thurman, E.M.; Bastian, K.C.; Mollhagen, T.

    2000-01-01

    During the summer of 1997, water samples were collected and analyzed for pesticides from 32 playa lakes of the High Plains that receive drainage from both cotton and corn agriculture in West Texas. The major cotton herbicides detected in the water samples were diuron, fluometuron, metolachlor, norflurazon, and prometryn. Atrazine and propazine, corn and sorghum herbicides, were also routinely detected in samples from the playa lakes. Furthermore, the metabolites of all the herbicides studied were found in the playa lake samples. In some cases, the concentration of metabolites was equal to or exceeded the concentration of the parent compound. The types of metabolites detected suggested that the parent compounds had been transported to and had undergone degradation in the playa lakes. The types of metabolites and the ratio of metabolites to parent compounds may be useful in indicating the time that the herbicides were transported to the playa lakes. The median concentration of total herbicides was 7.2 ??g/l, with the largest total concentrations exceeding 30 ??g/l. Organophosphate insecticides were detected in only one water sample. Further work will improve the understanding of the fate of these compounds in the playa lake area. Copyright (C) 2000 Elsevier Science B.V.

  13. Biological correlates of modernization in a Guatemalan highland municipio.

    PubMed

    Scholl, T O; Odell, M E

    1976-01-01

    The demographic correlates of modernization were studied in a municipio of the Guatemalan highlands using, as indicators of modernization, the introduction of chemical fertilizers and of a religous revitalization movement. Accion Catolica. Records, taken from interviews, of 340 women divided into declines (decennial groups) within ten-year birth cohorts extending from before 1925 to 1954, were checked for representativeness against the birth registries for the entire municipio for the years 1965-69.

  14. Biological correlates of modernization in a Guatemalan highland municipio.

    PubMed

    Scholl, T O; Odell, M E

    1976-01-01

    The demographic correlates of modernization were studied in a municipio of the Guatemalan highlands using, as indicators of modernization, the introduction of chemical fertilizers and of a religous revitalization movement. Accion Catolica. Records, taken from interviews, of 340 women divided into declines (decennial groups) within ten-year birth cohorts extending from before 1925 to 1954, were checked for representativeness against the birth registries for the entire municipio for the years 1965-69. PMID:1275431

  15. Grass buffers for playas in agricultural landscapes: An annotated bibliography

    USGS Publications Warehouse

    Melcher, Cynthia P.; Skagen, Susan K.

    2005-01-01

    References on best management practices (BMPs) for agricultural lands were included because certain BMPs are crucial for informing decisions about buffer design/ effectiveness and overall playa ecology. We also included various papers that increase the spectrum of time over which buffer theories and practices have evolved. An unannotated section lists references that we did not prioritize for annotation and references that may be helpful but were beyond the scope of this document. Finally, we provide notes on conversations we had with scientists, land managers, and other buffer experts whom we consulted, and their contact information. We conclude the bibliography with appendices of common and scientific names of birds and plants and acronyms used in both the bibliography. In the annotations, italicized text signifies our own editorial remarks. Readers should also note that much of the work on buffers has been designed using English units of measure rather than metrics; in most cases, their results have been converted to metrics for publication, explaining the seemingly odd or irregular buffer widths and other parameters reported.

  16. The response of playa and sabkha hydraulics and mineralogy to climate forcing.

    PubMed

    Tyler, Scott W; Muñoz, José F; Wood, Warren W

    2006-01-01

    Dry playa lakes and sabkhat often represent the terminus of large ground water flow systems and act as integrators of both upgradient (recharge) and downgradient discharge (evaporation). Ground water levels beneath playa/sabkha systems show a variety of surprising responses driven by large evaporation demands and chemical processes not typically encountered in more humid regions. When the water table is very close to the land surface, almost instantaneous rises can be observed with little observed change in either upgradient ground water recharge or potential evaporation. Conversely, when water tables are several meters below the playa surface, water table responses to interannual variability of recharge can be damped and lag significantly behind such changes. This review of the dynamics of shallow water tables in playa lakes and sabkhat discusses the pertinent hydraulic and solute processes and extracts a simple but comprehensive model based on soil physics for predicting the water table response to either upstream recharge changes or changes in potential evaporation at the playa/sabkha. Solutes and associated authigenic minerals are also shown to be important in discriminating both the causes and effects of water level fluctuations. PMID:16681514

  17. Lithostratigraphy and geochronology of fills in small playa basins on the Southern High Plains, United States

    SciTech Connect

    Holliday, V.T.; Hovorka, S.D.; Gustavson, T.C.

    1996-08-01

    Playa basins are small depressions (typically <=1.5 km{sup 2}) on the Southern High Plains of northwestern Texas and eastern New Mexico. There are about 25000 playas in the region; they lie on the Blackwater Draw Formation (Pleistocene), a widespread eolin deposit, and locally on the Ogallala Formation (Miocene-Pliocene). Understanding the lithostratigraphy and chronostratigraphy of the fill in the basins is important because it should (1) provide clues to the origin and evolution of playas, which have been long debated; (2) yield a paleoenvironmental record for the region; and (3) aid in understanding the history and future of the regional aquifer because playas are the principal source of recharge. Data from 19 playa basins, combined with published data from 4 other basins, show that the basin fill is composed of six distinctive facies: (1) lacustrine mud; (2) lacustrine carbonate; (3) lacustrine delta deposits; (4) eolian sand and silt; (5) eolian loam; and (6) accretionary eolian deposits (Blackwater Draw Formation). Dating is based on radiocarbon ages from the fill in 12 basins and from lunettes adjacent to 5 basins. All dated basins were present at the end of the Pleistocene and some were present in some form throughout the Pleistocene. These lithostratigraphic and chronostratigraphic relationships show that some basins have a prolonged history as depressions. 96 refs., 7 figs., 3 tabs.

  18. Modeling sediment accumulation in North American playa wetlands in response to climate change, 1940-2100

    USGS Publications Warehouse

    Burris, Lucy; Skagen, Susan K.

    2013-01-01

    Playa wetlands on the west-central Great Plains of North America are vulnerable to sediment infilling from upland agriculture, putting at risk several important ecosystem services as well as essential habitats and food resources of diverse wetland-dependent biota. Climate predictions for this semi-arid area indicate reduced precipitation which may alter rates of erosion, runoff, and sedimentation of playas. We forecasted erosion rates, sediment depths, and resultant playa wetland depths across the west-central Great Plains and examined the relative roles of land use context and projected changes in precipitation in the sedimentation process. We estimated erosion with the Revised Universal Soil Loss Equation (RUSLE) using historic values and downscaled precipitation predictions from three general circulation models and three emissions scenarios. We calibrated RUSLE results using field sediment measurements. RUSLE is appealing for regional scale modeling because it uses climate forecasts with monthly resolution and other widely available values including soil texture, slope and land use. Sediment accumulation rates will continue near historic levels through 2070 and will be sufficient to cause most playas (if not already filled) to fill with sediment within the next 100 years in the absence of mitigation. Land use surrounding the playa, whether grassland or tilled cropland, is more influential in sediment accumulation than climate-driven precipitation change.

  19. Opposing environmental gradients govern vegetation zonation in an intermountain playa

    USGS Publications Warehouse

    Sanderson, J.S.; Kotliar, N.B.; Steingraeber, D.A.

    2008-01-01

    Vegetation zonation was investigated at an intermountain playa wetland (Mishak Lakes) in the San Luis Valley (SLV) of southern Colorado. Plant composition and abiotic conditions were quantified in six vegetation zones. Reciprocal transplants were performed to test the importance of abiotic factors in governing zonation. Abiotic conditions differed among several vegetation zones. Prolonged inundation led to anaerobic soils in the Eleocharis palustris and the submerged aquatics zones, on the low end of the site's 1.25 m elevation gradient. On the high end of the gradient, soil salinity and sodicity (a measure of exchangeable sodium) were high in the Distichlis spicata zone (electrical conductivity, EC = 5.3 dS/m, sodium absorption ratio, SAR = 44.0) and extreme in the Sarcobatus vermiculatus zone (EC = 21 dS/m, SAR = 274). Transplanted species produced maximum biomass in the zone where they originated, not in any other higher or lower vegetation zone. The greatest overall transplant effect occurred for E. palustris, which experienced a ??? 77% decline in productivity when transplanted to other zones. This study provides evidence that physical factors are a major determinant of vegetation zone composition and distribution across the entire elevation gradient at Mishak Lakes. Patterns at Mishak Lakes arise from counter-directional stress gradients: a gradient from anaerobic to well-oxygenated from basin bottom to upland and a gradient from extremely high salinity to low salinity in the opposing direction. Because abiotic conditions dominate vegetation zonation, restoration of the altered hydrologic regime of this wetland to a natural hydrologic regime may be sufficient to re-establish many of the natural biodiversity functions provided by these wetlands. ?? 2008 The Society of Wetland Scientists.

  20. Water regime of Playa Lakes from southern Spain: conditioning factors and hydrological modeling.

    PubMed

    Moral, Francisco; Rodriguez-Rodriguez, Miguel; Beltrán, Manuel; Benavente, José; Cifuentes, Victor Juan

    2013-07-01

    Andalusia's lowland countryside has a network of small geographically isolated playa lakes scattered across an area of 9000 km2 whose watersheds are mostly occupied by clayey rocks. The hydrological model proposed by the authors seeks to find equilibrium among usefulness, simplicity, and applicability to isolated playas in a semiarid context elsewhere. Based in such model, the authors have used monthly climatic data, water stage measurements, and the basin morphometry of a particular case (Los Jarales playa lake) to calibrate the soil water budget in the catchment and the water inputs from the watershed (runoff plus groundwater flow) at different scales, from monthly to daily. After the hydrologic model was calibrated, the authors implemented simulations with the goal of reproducing the past hydrological dynamics and forecasting water regime changes that would be caused by a modification of the wetland morphometry.

  1. Effectiveness of vegetation buffers surrounding playa wetlands at contaminant and sediment amelioration

    USGS Publications Warehouse

    Haukos, David A.; Johnson, Lacrecia A.; Smith, Loren M.; McMurry, Scott T.

    2016-01-01

    Playa wetlands, the dominant hydrological feature of the semi-arid U.S. High Plains providing critical ecosystem services, are being lost and degraded due to anthropogenic alterations of the short-grass prairie landscape. The primary process contributing to the loss of playas is filling of the wetland through accumulation of soil eroded and transported by precipitation from surrounding cultivated watersheds. We evaluated effectiveness of vegetative buffers surrounding playas in removing metals, nutrients, and dissolved/suspended sediments from precipitation runoff. Storm water runoff was collected at 10-m intervals in three buffer types (native grass, fallow cropland, and Conservation Reserve Program). Buffer type differed in plant composition, but not in maximum percent removal of contaminants. Within the initial 60 m from a cultivated field, vegetation buffers of all types removed >50% of all measured contaminants, including 83% of total suspended solids (TSS) and 58% of total dissolved solids (TDS). Buffers removed an average of 70% of P and 78% of N to reduce nutrients entering the playa. Mean maximum percent removal for metals ranged from 56% of Na to 87% of Cr. Maximum removal was typically at 50 m of buffer width. Measures of TSS were correlated with all measures of metals and nutrients except for N, which was correlated with TDS. Any buffer type with >80% vegetation cover and 30–60 m in width would maximize contaminant removal from precipitation runoff while ensuring that playas would continue to function hydrologically to provide ecosystem services. Watershed management to minimize erosion and creations of vegetation buffers could be economical and effective conservation tools for playa wetlands.

  2. Effectiveness of vegetation buffers surrounding playa wetlands at contaminant and sediment amelioration.

    PubMed

    Haukos, David A; Johnson, Lacrecia A; Smith, Loren M; McMurry, Scott T

    2016-10-01

    Playa wetlands, the dominant hydrological feature of the semi-arid U.S. High Plains providing critical ecosystem services, are being lost and degraded due to anthropogenic alterations of the short-grass prairie landscape. The primary process contributing to the loss of playas is filling of the wetland through accumulation of soil eroded and transported by precipitation from surrounding cultivated watersheds. We evaluated effectiveness of vegetative buffers surrounding playas in removing metals, nutrients, and dissolved/suspended sediments from precipitation runoff. Storm water runoff was collected at 10-m intervals in three buffer types (native grass, fallow cropland, and Conservation Reserve Program). Buffer type differed in plant composition, but not in maximum percent removal of contaminants. Within the initial 60 m from a cultivated field, vegetation buffers of all types removed >50% of all measured contaminants, including 83% of total suspended solids (TSS) and 58% of total dissolved solids (TDS). Buffers removed an average of 70% of P and 78% of N to reduce nutrients entering the playa. Mean maximum percent removal for metals ranged from 56% of Na to 87% of Cr. Maximum removal was typically at 50 m of buffer width. Measures of TSS were correlated with all measures of metals and nutrients except for N, which was correlated with TDS. Any buffer type with >80% vegetation cover and 30-60 m in width would maximize contaminant removal from precipitation runoff while ensuring that playas would continue to function hydrologically to provide ecosystem services. Watershed management to minimize erosion and creations of vegetation buffers could be economical and effective conservation tools for playa wetlands.

  3. Microbial mats in playa lakes and other saline habitats: Early Mars analog?

    NASA Technical Reports Server (NTRS)

    Bauld, John

    1989-01-01

    Microbial mats are cohesive benthic microbial communities which inhabit various Terra (Earth-based) environments including the marine littoral and both permanent and ephemeral (playa) saline lakes. Certain geomorphological features of Mars, such as the Margaritifer Sinus, were interpreted as ancient, dried playa lakes, presumably formed before or during the transition to the present Mars climate. Studies of modern Terran examples suggest that microbial mats on early Mars would have had the capacity to survive and propagate under environmental constraints that would have included irregularly fluctuating regimes of water activity and high ultraviolet flux. Assuming that such microbial communities did indeed inhabit early Mars, their detection during the Mars Rover Sample Return (MRSR) mission depends upon the presence of features diagnostic of the prior existence of these communities or their component microbes or, as an aid to choosing suitable landing, local exploration or sampling sites, geomorphological, sedimentological or chemical features characteristic of their playa lake habitats. Examination of modern Terran playas (e.g., the Lake Eyre basin) shows that these features span several orders of magnitude in size. While stromatolites are commonly centimeter-meter scale features, bioherms or fields of individuals may extend to larger scales. Preservation of organic matter (mats and microbes) would be favored in topographic lows such as channels or ponds of high salinity, particularly those receiving silica-rich groundwaters. These areas are likely to be located near former zones of groundwater emergence and/or where flood channels entered the paleo-playa. Fossil playa systems which may aid in assessing the applicability of this particular Mars analog include the Cambrian Observatory Hill Beds of the Officer Basin and the Eocene Wilkins Peak Member of the Green River Formation.

  4. Effectiveness of vegetation buffers surrounding playa wetlands at contaminant and sediment amelioration.

    PubMed

    Haukos, David A; Johnson, Lacrecia A; Smith, Loren M; McMurry, Scott T

    2016-10-01

    Playa wetlands, the dominant hydrological feature of the semi-arid U.S. High Plains providing critical ecosystem services, are being lost and degraded due to anthropogenic alterations of the short-grass prairie landscape. The primary process contributing to the loss of playas is filling of the wetland through accumulation of soil eroded and transported by precipitation from surrounding cultivated watersheds. We evaluated effectiveness of vegetative buffers surrounding playas in removing metals, nutrients, and dissolved/suspended sediments from precipitation runoff. Storm water runoff was collected at 10-m intervals in three buffer types (native grass, fallow cropland, and Conservation Reserve Program). Buffer type differed in plant composition, but not in maximum percent removal of contaminants. Within the initial 60 m from a cultivated field, vegetation buffers of all types removed >50% of all measured contaminants, including 83% of total suspended solids (TSS) and 58% of total dissolved solids (TDS). Buffers removed an average of 70% of P and 78% of N to reduce nutrients entering the playa. Mean maximum percent removal for metals ranged from 56% of Na to 87% of Cr. Maximum removal was typically at 50 m of buffer width. Measures of TSS were correlated with all measures of metals and nutrients except for N, which was correlated with TDS. Any buffer type with >80% vegetation cover and 30-60 m in width would maximize contaminant removal from precipitation runoff while ensuring that playas would continue to function hydrologically to provide ecosystem services. Watershed management to minimize erosion and creations of vegetation buffers could be economical and effective conservation tools for playa wetlands. PMID:27423768

  5. Numerous Unpaired Meteorites Exposed on a Deflating Playa Lake at Lucerne Valley, California

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.; Verish, Robert S.; Moore, Carleton B.; Oriti, Ronald A.

    2000-01-01

    Out of 16 well-characterized 1 to 37 g meteorite specimens recovered from Lucerne Dry Lake (an approximately 3 7 km playa in the southern Mojave Desert of California), there are 9 separate ordinary chondrite finds. The ratio of independent meteorites to total number of specimens (0.6) is among the highest in the world. This is due to lack of initial deep burial of the small meteorites, significant deflation of the lake exposing falls of individual stones (or small numbers of paired meteorites), and the absence of a large meteorite shower in the region. Playas appear to be excellent candidates for high-yield meteorite-collecting areas.

  6. The utilization of ERTS-1-generated photographs in the evaluation of the Iranian playas as potential locations for economic and engineering development. [hydrology and morphology of playa soils

    NASA Technical Reports Server (NTRS)

    Krinsley, D. B. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Hydrologic inventories, throughout the year, were made in interior basins that have not been measured previously because of their inaccessibility. Interior basins during the last ERTS-1 year (August 1972 to August 1973) had driest ground conditions in late September 1972 and had wettest ground conditions from March through May 1973, depending upon location. Bearing strengths of playa soils can be inferred from the changing hydrologic conditions through the seasons as recorded by ERTS-1, with prior ground control. Slight differences in salt-crust morphology and in moisture contest of playa soils can be greatly enhanced by rationing and stretching techniques. Differences in water area and silt content can be enhanced by using a three-stage photographic masking technique employing bands 4, 5, and 7.

  7. Hydrogeologic processes in saline systems: Playas, sabkhas, and saline lakes

    USGS Publications Warehouse

    Yechieli, Y.; Wood, W.W.

    2002-01-01

    Pans, playas, sabkhas, salinas, saline lakes, and salt flats are hydrologically similar, varying only in their boundary conditions. Thus, in evaluating geochemical processes in these systems, a generic water and solute mass-balance approach can be utilized. A conceptual model of a coastal sabkha near the Arabian Gulf is used as an example to illustrate the various water and solute fluxes. Analysis of this model suggests that upward flux of ground water from underlying formations could be a major source of solutes in the sabkha, but contribute only a small volume of the water. Local rainfall is the main source of water in the modeled sabkha system with a surprisingly large recharge-to-rainfall ratio of more than 50%. The contribution of seawater to the solute budget depends on the ratio of the width of the supratidal zone to the total width and is generally confined to a narrow zone near the shoreline of a typical coastal sabkha. Because of a short residence time of water, steady-state flow is expected within a short time (50,000 years). The solute composition of the brine in a closed saline system depends largely on the original composition of the input water. The high total ion content in the brine limits the efficiency of water-rock interaction and absorption. Because most natural systems are hydrologically open, the chemistry of the brines and the associated evaporite deposits may be significantly different than that predicted for hydrologically closed systems. Seasonal changes in temperature of the unsaturated zone cause precipitation of minerals in saline systems undergoing evaporation. Thus, during the hot dry season months, minerals exhibit retrograde solubility so that gypsum, anhydrite and calcite precipitate. Evaporation near the surface is also a major process that causes mineral precipitation in the upper portion of the unsaturated zone (e.g. halite and carnallite), provided that the relative humidity of the atmosphere is less than the activity of water

  8. Water-Chemistry Evolution and Modeling of Radionuclide Sorption and Cation Exchange during Inundation of Frenchman Flat Playa

    SciTech Connect

    Hershey, Ronald; Cablk, Mary; LeFebre, Karen; Fenstermaker, Lynn; Decker, David

    2013-08-01

    Atmospheric tests and other experiments with nuclear materials were conducted on the Frenchman Flat playa at the Nevada National Security Site, Nye County, Nevada; residual radionuclides are known to exist in Frenchman Flat playa soils. Although the playa is typically dry, extended periods of winter precipitation or large single-event rainstorms can inundate the playa. When Frenchman Flat playa is inundated, residual radionuclides on the typically dry playa surface may become submerged, allowing water-soil interactions that could provide a mechanism for transport of radionuclides away from known areas of contamination. The potential for radionuclide transport by occasional inundation of the Frenchman Flat playa was examined using geographic information systems and satellite imagery to delineate the timing and areal extent of inundation; collecting water samples during inundation and analyzing them for chemical and isotopic content; characterizing suspended/precipitated materials and archived soil samples; modeling water-soil geochemical reactions; and modeling the mobility of select radionuclides under aqueous conditions. The physical transport of radionuclides by water was not evaluated in this study. Frenchman Flat playa was inundated with precipitation during two consecutive winters in 2009-2010 and 2010-2011. Inundation allowed for collection of multiple water samples through time as the areal extent of inundation changed and ultimately receded. During these two winters, precipitation records from a weather station in Frenchman Flat (Well 5b) provided information that was used in combination with geographic information systems, Landsat imagery, and image processing techniques to identify and quantify the areal extent of inundation. After inundation, water on the playa disappeared quickly, for example, between January 25, 2011 and February 10, 2011, a period of 16 days, 92 percent of the areal extent of inundation receded (2,062,800 m2). Water sampling provided

  9. A water resource assessment of the playa lakes of the Texas High Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Texas Water Development Board (TWDB) staff are studying the water-resource potential of playa lakes in the Texas High Plains in partnership with the U. S. Department of Agriculture— Agricultural Research Service and Texas Tech University. Phase 1 of the research seeks to measure the volume of water ...

  10. Monitoring infiltration and recharge of playa lakes in the Texas Southern High Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Preliminary results from playa lakes monitored by the Texas Water Development Board (TWDB) suggest that a small volume of deep infiltration and recharge to the Ogallala aquifer occurs along the margins of the lake beds, while the majority of infiltration associated with a typical inundation remains ...

  11. Biophysical Controls over Carbon and Nitrogen Stocks in Desert Playa Wetlands

    NASA Astrophysics Data System (ADS)

    McKenna, O. P.; Sala, O. E.

    2014-12-01

    Playas are ephemeral desert wetlands situated at the bottom of closed catchments. Desert playas in the Southwestern US have not been intensively studied despite their potential importance for the functioning of desert ecosystems. We want to know which geomorphic and ecological variables control of the stock size of soil organic carbon, and soil total nitrogen in playas. We hypothesize that the magnitude of carbon and nitrogen stocks depends on: (a) catchment size, (b) catchment slope, (d) catchment vegetation cover, (e) bare-ground patch size, and (f) catchment soil texture. We chose thirty playas from across the Jornada Basin (Las Cruces, NM) ranging from 0.5-60ha in area and with varying catchment characteristics. We used the available 5m digital elevation map (DEM) to calculate the catchment size and catchment slope for these thirty playas. We measured percent cover, and patch size using the point-intercept method with three 10m transects in each catchment. We used the Bouyoucos-hydrometer soil particle analysis to determine catchment soil texture. Stocks of organic carbon and nitrogen were measured from soil samples at four depths (0-10 cm, 10-30 cm, 30-60 cm, 60-100 cm) using C/N combustion analysis. In terms of nitrogen and organic carbon storage, we found soil nitrogen values in the top 10cm ranging from 41.963-214.365 gN/m2, and soil organic carbon values in the top 10cm ranging from 594.339-2375.326 gC/m2. The results of a multiple regression analysis show a positive relationship between catchment slope and both organic carbon and nitrogen stock size (nitrogen: y= 56.801 +47.053, R2=0.621; organic carbon: y= 683.200 + 499.290x, R2= 0.536). These data support our hypothesis that catchment slope is one of factors controlling carbon and nitrogen stock in desert playas. We also applied our model to the 69 other playas of the Jornada Basin and estimated stock sizes (0-10cm) between 415.07-447.97 Mg for total soil nitrogen and 4627.99-5043.51 Mg for soil organic

  12. Using the WRF model to simulate the playa breeze over Dugway Proving Ground

    NASA Astrophysics Data System (ADS)

    Spade, Daniela Maria

    The aim of this model and observation based study is to investigate the Advanced Research Weather Research and Forecasting Model's (WRF-ARW, although WRF from hereout) ability to simulate the three-dimensional structure of playa breezes and drainage flows occurring in Dugway Proving Ground, Utah using sub-km nesting in addition to improved land use and terrain datasets (as compared to the default datasets provided with WRF), in addition to studying the diurnal cycle and interactions between the playa breeze and drainage flows. A playa breeze is a thermally forced air circulation system that develops near the edge of playas, which have properties distinct from the surrounding land cover, including a higher thermal conductivity, a higher albedo due to the presence of a thin salt crust at the surface, sparse vegetation cover relative to the surrounding land cover, and a higher latent heat flux. The combination of each of these characteristics produces a thermally direct circulation, with low-level flow away from the playa during the day and toward the playa at night, the result of a cooler playa during the day and a warmer playa at night. Five model runs were performed using the Noah land Surface model, each employing a four telescoping nest strategy. Each model run was given a different set of physical parameterizations, with some using GFS model output and others using NAM model output. The object behind utilizing five model runs was to isolate the impacts made by the differing model parameterization schemes used for each simulation. This was accomplished by comparing the model run output to in situ weather observations, provided courtesy of the Mountain Terrain Atmospheric Modeling and Observation Program (MATERHORN), an ongoing Multidisciplinary University Research Initiative (MURI) sponsored by the Office of Naval Research with the University of Notre Dame acting as Project Lead. It was found that each of the five model simulations tended to produce a longer

  13. Ratosa playa lake in southern Spain. Karst pan or compound sink?

    PubMed

    Rodríguez-Rodríguez, Miguel; Martos-Rosillo, Sergio; Pedrera, Antonio; Benavente-Herrera, José

    2015-04-01

    In Andalusia (Spain), there are more than 45 semiarid playa lakes protected as natural reserves and related to karstic outcrops. Some of them are located over regional karstic aquifers and have internal drainage networks with sporadic surface outlets, such as sinkholes (compound sinks), but the majority of such playas have no internal drainage systems, so the only water output is evaporation (karst pans). Karst pans are perched and disconnected from the groundwater system. The fact that the Ratosa playa lake is partially located over a karstic Sierra, as well as other hydromorphological observations, it is suggested that the system could be of a compound type, but a detailed hydrogeological analysis showed that the playa is disconnected from the aquifer, so it is in fact a karst pan. Once the hydrological functioning had been established, a monthly water balance for a 10-year period (1998-2008), enabled us to reproduce the evolution of the water level of the playa lake. Estimations of runoff were carried out by a soil water estimate for a water holding capacity in the soil of 191 mm. Results show a good correlation (>90%) after calibration with the time series of water level in the lake for the same period confirming geological observations. Our results highlight that this water body is extremely vulnerable to hydrological alterations of its watershed caused by human activities, particularly those related to land-use change for agriculture. For this reason, we propose a new protection zone, based on hydrological knowledge, instead of the present Peripheral Area of Protection. PMID:25810083

  14. Ratosa playa lake in southern Spain. Karst pan or compound sink?

    PubMed

    Rodríguez-Rodríguez, Miguel; Martos-Rosillo, Sergio; Pedrera, Antonio; Benavente-Herrera, José

    2015-04-01

    In Andalusia (Spain), there are more than 45 semiarid playa lakes protected as natural reserves and related to karstic outcrops. Some of them are located over regional karstic aquifers and have internal drainage networks with sporadic surface outlets, such as sinkholes (compound sinks), but the majority of such playas have no internal drainage systems, so the only water output is evaporation (karst pans). Karst pans are perched and disconnected from the groundwater system. The fact that the Ratosa playa lake is partially located over a karstic Sierra, as well as other hydromorphological observations, it is suggested that the system could be of a compound type, but a detailed hydrogeological analysis showed that the playa is disconnected from the aquifer, so it is in fact a karst pan. Once the hydrological functioning had been established, a monthly water balance for a 10-year period (1998-2008), enabled us to reproduce the evolution of the water level of the playa lake. Estimations of runoff were carried out by a soil water estimate for a water holding capacity in the soil of 191 mm. Results show a good correlation (>90%) after calibration with the time series of water level in the lake for the same period confirming geological observations. Our results highlight that this water body is extremely vulnerable to hydrological alterations of its watershed caused by human activities, particularly those related to land-use change for agriculture. For this reason, we propose a new protection zone, based on hydrological knowledge, instead of the present Peripheral Area of Protection.

  15. Strontium isotope geochemistry of soil and playa deposits near Yucca Mountain, Nevada

    SciTech Connect

    Marshall, B.D.; Mahan, S.A.

    1994-12-31

    The isotopic composition of strontium contained in the carbonate fractions of soils provides an excellent tracer which can be used to test models for their origin. This paper reports data on surface coatings and cements, eolian sediments, playas and alluvial fan soils which help to constrain a model for formation of the extensive calcretes and fault infillings in the Yucca Mountain region. The playas contain carbonate with a wide range of strontium compositions; further work will be required to fully understand their possible contributions to the pedogenic carbonate system. Soils from an alluvial fan to the west of Yucca Mountain show that only small amounts of strontium are derived from a fan draining a carbonate terrane have strontium component. Although much evidence points to an eolian source for at least some of the strontium in the pedogenic carbonates near Yucca Mountain, an additional component or past variation of strontium composition in the eolian source is required to model the pedogenic carbonate system.

  16. Sliding rocks on Racetrack Playa, Death Valley National Park: first observation of rocks in motion.

    PubMed

    Norris, Richard D; Norris, James M; Lorenz, Ralph D; Ray, Jib; Jackson, Brian

    2014-01-01

    The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s. Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action. We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras. The largest observed rock movement involved > 60 rocks on December 20, 2013 and some instrumented rocks moved up to 224 m between December 2013 and January 2014 in multiple move events. In contrast with previous hypotheses of powerful winds or thick ice floating rocks off the playa surface, the process of rock movement that we have observed occurs when the thin, 3 to 6 mm, "windowpane" ice sheet covering the playa pool begins to melt in late morning sun and breaks up under light winds of -4-5 m/s. Floating ice panels 10 s of meters in size push multiple rocks at low speeds of 2-5 m/min. along trajectories determined by the direction and velocity of the wind as well as that of the water flowing under the ice. PMID:25162535

  17. Sliding Rocks on Racetrack Playa, Death Valley National Park: First Observation of Rocks in Motion

    PubMed Central

    Lorenz, Ralph D.; Ray, Jib; Jackson, Brian

    2014-01-01

    The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s. Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action. We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras. The largest observed rock movement involved >60 rocks on December 20, 2013 and some instrumented rocks moved up to 224 m between December 2013 and January 2014 in multiple move events. In contrast with previous hypotheses of powerful winds or thick ice floating rocks off the playa surface, the process of rock movement that we have observed occurs when the thin, 3 to 6 mm, “windowpane” ice sheet covering the playa pool begins to melt in late morning sun and breaks up under light winds of ∼4–5 m/s. Floating ice panels 10 s of meters in size push multiple rocks at low speeds of 2–5 m/min. along trajectories determined by the direction and velocity of the wind as well as that of the water flowing under the ice. PMID:25162535

  18. Filed-Analog Study: Efficiency of microbial fossilization in sulfate-rich playas

    NASA Astrophysics Data System (ADS)

    Glamoclija, M.; Zeidan, M.; Potochniak, S.

    2015-12-01

    The samples with the highest priority for sample return will be samples that contain potential life signatures. Sulfate-rich salts have been identified as important component of Mars sedimentary deposits, illustrating the importance of near-surface hydrological processes during the planet's history. The presence of Noachian/early Hesperian sulfate-rich deposits have been identified by the MER's Opportunity at Meridiani Planum and by MRO mission in sedimentary sequences within Gale crater, the Mars Science Laboratory landing site. White Sands National Monument, which we are using as a terrestrial analog in our study, holds active playas that may contain different sizes of water bodies during the year. Alkali Flat contains also preserved deposits of Pleistocene Lake Otero. The presence of a range of modern playas and equivalent Pleistocene deposits allows for an excellent comparison of these different extreme transitional habitats and potential of preservation of organics in an evaporitic playa setting. We have performed shallow drilling (1m) of the Lake Lucero deposits and of Lake Otero evaporitic sequence. The XRD analysis revealed that samples are mainly composed of gypsum and minor mineral phases as brushite, halite and quartz. SEM/EDS revealed the presence of amorphous phases such as halite, glauberite, magnesium chlorite salt, and diatom shells and biofilm. Biofilm is found in near surface samples, which may be attributed to microbial adaptation to desert environment and considered as one of the characteristics of modern and not fossil microbial communities. The compositional difference of salt precipitates associated with potentially geologically old biofilm and the modern counterpart are still ongoing and our findings will be presented at the conference. Further, comparison of environmental physicochemical conditions and molecular biology will be used to determine the characteristics of modern microbial habitats/deposits and to attempt to distinguish them

  19. Investigating playa surface textures: The impact of chemistry and environment on surface morphology and dust

    NASA Astrophysics Data System (ADS)

    Tollerud, H. J.; Fantle, M. S.

    2010-12-01

    Mineral dust is an important component of geochemical cycles, but its impact on those cycles is not thoroughly understood. For instance, dust inputs to the ocean have been suggested to affect the iron cycle by stimulating natural iron fertilization, which then could modify climate. The influence of dust on geochemical cycles is determined by the chemical and mineralogical composition of dust inputs, which is governed in turn by the composition of dust source regions. A loose, unconsolidated surface texture is more easily ablated by wind, and so a location where composition and environmental characteristics encourage this type of surface is more likely to produce dust and influence geochemical cycles. Also, if evaporation concentrates evaporites such as calcite at the surface of a dust producing region, dust Ca concentrations are likely to be higher. Playas can be regionally significant dust source regions, and they are amenable to study as their surface textures often vary significantly across small areas. This study investigates surface processes experimentally, and compares the results to observations of surface texture in a natural playa system (the Black Rock Desert, Nevada). We dry surfaces with 25% to 75% clay and quartz at 40°C for approximately a day, wet the surface to simulate rain, and then repeat the cycle multiple times. We estimate surface roughness, measure surface strength with a penetrometer, and investigate thermal characteristics with an IR camera (wavelength range 8-12μm). We find that textures similar to those in playas can be reproduced with cycles of wetting and drying, such as might occur in an arid environment with intermittent rain. We investigate the addition of calcite and halite, since their precipitation potentially can disrupt the clay surfaces through the formation and expansion of crystals, thereby linking the chemical composition with the disruption of a strong surface texture and an increased chance of dust production. In the

  20. Effects of landuse and precipitation on pesticides and water quality in playa lakes of the southern high plains.

    PubMed

    Anderson, Todd A; Salice, Christopher J; Erickson, Richard A; McMurry, Scott T; Cox, Stephen B; Smith, Loren M

    2013-06-01

    The 25000 playa wetlands within the Southern High Plains (SHP) of the United States of America (USA) are the dominant hydrogeomorphic feature in the region, providing habitat for numerous plants and wildlife. The SHP are among the most intensively cultivated regions; there are concerns over the degradation and/or loss of playa wetland habitat. We examined water quality in playa wetlands surrounded by both grassland and agriculture and measured water concentrations of pesticides used on cotton (acephate, trifluralin, malathion, pendimethalin, tribufos, bifenthrin, λ-cyhalothrin, acetamiprid, and thiamethoxam), the dominant crop in the SHP. Pesticides used on cotton were detected in water samples collected from all playas. Precipitation events and the amount of cultivation were related to pesticide concentrations in sediment and water. Our results show that pesticide concentrations were related in some circumstances to time, precipitation, and tilled-index for some but not all pesticides. We further compared measured pesticide concentrations in playas to toxicity benchmarks used by the US EPA in pesticide ecological risk assessments to obtain some insight into the potential for ecological effects. For all pesticides in water, the maximum measured concentrations exceeded at least one toxicity benchmark, while median concentrations did not exceed any benchmarks. This analysis indicates that there is a potential for adverse effects of pesticides to aquatic organisms. PMID:23541358

  1. Dust emissions from undisturbed and disturbed, crusted playa surfaces: Cattle trampling effects

    NASA Astrophysics Data System (ADS)

    Baddock, Matthew C.; Zobeck, Ted M.; Van Pelt, R. Scott; Fredrickson, Ed L.

    2011-06-01

    Dry playa lake beds can be significant sources of fine dust emission. This study used a portable field wind tunnel to quantify the PM 10 emissions from a bare, fine-textured playa surface located in the far northern Chihuahua Desert. The natural, undisturbed crust and its subjection to two levels of animal disturbance (one and ten cow passes) were tested. The wind tunnel generated dust emissions under controlled conditions for firstly an initial blow-off of the surface, followed by two longer runs with sand added to the flow as an abrader material. Dust was measured using a GRIMM particle monitor. For the study playa, no significant differences in PM 10 concentration and emission flux were found between the untrampled surface and following a single animal pass. This was the case for both the initial blow-offs and tests on plots under a steady abrader rate. Significantly higher dust loading was only associated with the effect of 10 animal passes. In the blow-offs, the higher PM 10 yield after 10 passes reflected the greater availability of easily entrainable fine particles. Under abrasion, the effect of the heaviest trampling increased the emission flux by a third and abrasion efficiency by around 50% more than values on the untrampled surface. This enhanced abrasion efficiency persisted for a 30 min period under abrasion before the positive effect of the disturbance was no longer evident. The findings highlight the role of a threshold of disturbance that determines if supply-limited surfaces will exhibit enhanced wind erosion or not after undergoing perturbation.

  2. Characteristics of playa deposits as seen on SIR-A, Seasat and Landsat coregistered data

    NASA Technical Reports Server (NTRS)

    Rebillard, PH.; Naraghi, M.

    1984-01-01

    A classification technique currently under development has been applied for the qualitative study of a playa located in Northeastern Algeria using coregistered SIR-A, Seasat and Landsat MSS 7 data. This classification which is texture based can be applied to only single band imagery at this time. The first results are very encouraging and reach conclusions similar to those obtained with more time consuming classifiers. The signature of each class is well expressed for the Landsat picture. Misclasifications occur with the SIR-A or Seasat images.

  3. Aeolian responses to climate variability during the past century on Mesquite Lake Playa, Mojave Desert

    NASA Astrophysics Data System (ADS)

    Whitney, J. W.; Breit, G. N.; Buckingham, S. E.; Reynolds, R. L.; Bogle, R. C.; Luo, L.; Goldstein, H. L.; Vogel, J. M.

    2015-02-01

    The erosion and deposition of sediments by wind from 1901 to 2013 have created large changes in surface features of Mesquite Lake playa in the Mojave Desert. The decadal scale recurrence of sand-sheet development, migration, and merging with older dunes appears related to decadal climatic changes of drought and wetness as recorded in the precipitation history of the Mojave Desert, complemented by modeled soil-moisture index values. Historical aerial photographs, repeat land photographs, and satellite images document the presence and northward migration of a mid-20th century sand sheet that formed during a severe regional drought that coincided with a multi-decadal cool phase of the Pacific Decadal Oscillation (PDO). The sand sheet slowly eroded during the wetter conditions of the subsequent PDO warm phase (1977-1998) due to a lack of added sediment. Sand cohesion gradually increased in the sand sheet by seasonal additions of salt and clay and by re-precipitation of gypsum, which resulted in the wind-carving of yardangs in the receding sand sheet. Smaller yardangs were aerodynamically shaped from coppice dunes with salt-clay crusts, and larger yardangs were carved along the walls and floor of trough blowouts. Evidence of a 19th century cycle of sand-sheet formation and erosion is indicated by remnants of yardangs, photographed in 1901 and 1916, that were found buried in the mid-20th century sand sheet. Three years of erosion measurements on the playa, yardangs, and sand sheets document relatively rapid wind erosion. The playa has lowered 20 to 40 cm since the mid-20th century and a shallow deflation basin has developed since 1999. Annually, 5-10 cm of surface sediment was removed from yardang flanks by a combination of wind abrasion, deflation, and mass movement. The most effective erosional processes are wind stripping of thin crusts that form on the yardang surfaces after rain events and the slumping of sediment blocks from yardang flanks. These wind

  4. Briny lakes on early Mars? Terrestrial intracrater playas and Martian candidates

    NASA Technical Reports Server (NTRS)

    Lee, P.

    1993-01-01

    Recently, salt-rich aqueous solutions have been invoked in the preterrestrial alteration of the Nakhla and Lafayette SNC meteorites. The findings substantiate the long-standing suspicion that salts are abundant on Mars and, more importantly, that brines have played a significant role in Martian hydrogeological history. Adding to the growing body of evidence, I report here on the identification of several unusual intracrater high-albedo features in the ancient cratered highlands of Mars, which I interpret as possible saline playas, or salt pans.

  5. Briny lakes on early Mars? Terrestrial intracrater playas and Martian candidates

    NASA Astrophysics Data System (ADS)

    Lee, P.

    Recently, salt-rich aqueous solutions have been invoked in the preterrestrial alteration of the Nakhla and Lafayette SNC meteorites. The findings substantiate the long-standing suspicion that salts are abundant on Mars and, more importantly, that brines have played a significant role in Martian hydrogeological history. Adding to the growing body of evidence, I report here on the identification of several unusual intracrater high-albedo features in the ancient cratered highlands of Mars, which I interpret as possible saline playas, or salt pans.

  6. Mapping playa evaporite minerals with AVIRIS data - A first report from Death Valley, California

    NASA Technical Reports Server (NTRS)

    Crowley, James K.

    1993-01-01

    The feasibility of using imaging spectrometry in studies of playa evaporites is demonstrated by mapping efflorescent salt crusts in Death Valley (California), using Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data and a recently developed least-squares spectral band-fitting algorithm. It is shown that it was possible to remotely identify eight different saline minerals, including three borates that have not been previously reported for the Death Valley efflorescent crusts: hydroboracite, pinnoite, and rivadavite. The three borates are locally important phases in the crusts; at least one of them, rivadavite, appears to be forming directly from brine.

  7. The application of remote sensing technology to the inventory of playa lakes in the High Plains of Texas

    NASA Technical Reports Server (NTRS)

    Wyatt, A. W.; Ellis, M. L.; Bell, A. E.

    1975-01-01

    The feasibility of using LANDSAT digital data to inventory the playa lakes of the High Plains region of Texas was investigated. The project will use the detection and mapping (DAM) package developed at NASA-Johnson Space Center. The economy of the High Plains region is dependent on ground water for irrigation and the Ogallala aquifer is being depleted faster than it is being recharged. The playa lakes represent a potential source of artificial recharge for the aquifer and an inventory is the first step in that direction.

  8. Numerical investigation of coupled density-driven flow and hydrogeochemical processes below playas

    NASA Astrophysics Data System (ADS)

    Hamann, Enrico; Post, Vincent; Kohfahl, Claus; Prommer, Henning; Simmons, Craig T.

    2015-11-01

    Numerical modeling approaches with varying complexity were explored to investigate coupled groundwater flow and geochemical processes in saline basins. Long-term model simulations of a playa system gain insights into the complex feedback mechanisms between density-driven flow and the spatiotemporal patterns of precipitating evaporites and evolving brines. Using a reactive multicomponent transport model approach, the simulations reproduced, for the first time in a numerical study, the evaporite precipitation sequences frequently observed in saline basins ("bull's eyes"). Playa-specific flow, evapoconcentration, and chemical divides were found to be the primary controls for the location of evaporites formed, and the resulting brine chemistry. Comparative simulations with the computationally far less demanding surrogate single-species transport models showed that these were still able to replicate the major flow patterns obtained by the more complex reactive transport simulations. However, the simulated degree of salinization was clearly lower than in reactive multicomponent transport simulations. For example, in the late stages of the simulations, when the brine becomes halite-saturated, the nonreactive simulation overestimated the solute mass by almost 20%. The simulations highlight the importance of the consideration of reactive transport processes for understanding and quantifying geochemical patterns, concentrations of individual dissolved solutes, and evaporite evolution.

  9. Trail formation by ice-shoved "sailing stones" observed at Racetrack Playa, Death Valley National Park

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.; Norris, J. M.; Jackson, B. K.; Norris, R. D.; Chadbourne, J. W.; Ray, J.

    2014-08-01

    Trails in the usually-hard mud of Racetrack Playa in Death Valley National Park attest to the seemingly-improbable movement of massive rocks on an exceptionally flat surface. The movement of these rocks, previously described as "sliding stones", "playa scrapers", "sailing stones" etc., has been the subject of speculation for almost a century but is an exceptionally rare phenomenon and until now has not been directly observed. Here we report documentation of multiple rock movement and trail formation events in the winter of 2013-2014 by in situ observation, video, timelapse cameras, a dedicated meteorological station and GPS tracking of instrumented rocks. Movement involved dozens of rocks, forming fresh trails typically of 10s of meters length at speeds of ~5 cm s-1 and were caused by wind stress on a transient thin layer of floating ice. Fracture and local thinning of the ice decouples some rocks from the ice movement, such that only a subset of rocks move in a given event.

  10. Hydrology and surface morphology of the Bonneville Salt Flats and Pilot Valley Playa, Utah

    USGS Publications Warehouse

    Lines, Gregory C.

    1979-01-01

    The Bonneville Salt Flats and Pilot Valley are in the western part of the Great Salt Lake Desert in northwest Utah. The areas are separate, though similar, hydrologic basins, and both contain a salt crust. The Bonneville salt crust covered about 40 square miles in the fall of 1976, and the salt crust in Pilot Valley covered 7 square miles. Both areas lack any noticeable surface relief (in 1976, 1.3 feet on the Bonneville salt crust and 0.3 foot on the Pilot Valley salt crust). The salt crust on the Salt Flats has been used for many years for automobile racing, and brines from shallow lacustrine deposits have been used for the production of potash. In recent years, there has been an apparent conflict between these two major uses of the area as the salt crust has diminished in both thickness and extent. Much of the Bonneville Racetrack has become rougher, and there has also been an increase in the amount of sediment on the south end of the racetrack. The Pilot Valley salt crust and surrounding playa have been largely unused. Evaporite minerals on the Salt Flats and the Pilot Valley playa are concentrated in three zones: (1) a carbonate zone composed mainly of authigenic clay-size carbonate minerals, (2) a sulfate zone composed mainly of authigenic gypsum, and (3) a chloride zone composed of crystalline halite (the salt crust). Five major types of salt crust were recognized on the Salt Flats, but only one type was observed in Pilot Valley. Geomorphic differences in the salt crust are caused by differences in their hydrologic environments. The salt crusts are dynamic features that are subject to change because of climatic factors and man's activities. Ground water occurs in three distinct aquifers in much of the western Great Salt Lake Desert: (1) the basin-fill aquifer, which yields water from conglomerate in the lower part of the basin fill, (2) the alluvial-fan aquifer, which yields water from sand and gravel along the western margins of both playas, and (3) the

  11. Multi-temporal water extent analysis of a hypersaline playa lake using Landsat Imagery

    NASA Astrophysics Data System (ADS)

    Kilic, Ecenur; Kamil Yilmaz, Koray; Lutfi Suzen, Mehmet

    2016-04-01

    Distinguishing inland water bodies from satellite imagery has always been one of the main practices of remote sensing. In some cases this differentiation can directly be obtained by visual interpretation. However, in case of hyper-saline playa lakes, presence of high albedo salt crust in the lake bed hampers visual interpretation and requires further attention. Lake Tuz is a hypersaline playa lake which is ranked as the second largest lake in Turkey. Spatio-temporal changes in lake water extent are important both economically and hydrologically including salt production, lake water balance, drought and over-exploitation issues. This study investigates the spatiotemporal changes in Lake Tuz water extent during the last decade using single-band thresholding and multi-band indices extracted from the multi-temporal Landsat 5 TM and Landsat 7 ETM+ images. The applicability of different satellite-derived indices including Normalized Difference Water Index (NDWI), Modified NDWI (MNDWI), Automated Water Extraction Index (AWEI) and Tasseled Cap Wetness (TCw) were investigated for the extraction of lake water extent from Landsat imagery. Our analysis indicated that, overall, NDWI is superior to other tested indices in separating wet/dry pixels over the lake bottom covered with salt crust. Using a NDWI thresholding procedure, the annual and seasonal variation in the Lake Tuz water extent were determined and further linked to hydro-meteorological variables such as precipitation.

  12. Playa Soil Moisture and Evaporation Dynamics During the MATERHORN Field Program

    NASA Astrophysics Data System (ADS)

    Hang, Chaoxun; Nadeau, Daniel F.; Jensen, Derek D.; Hoch, Sebastian W.; Pardyjak, Eric R.

    2016-06-01

    We present an analysis of field data collected over a desert playa in western Utah, USA in May 2013, the most synoptically active month of the year, as part of the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program. The results show that decreasing surface albedo, decreasing Bowen ratio and increasing net radiation with increasing soil moisture sustained a powerful positive feedback mechanism promoting large evaporation rates immediately following rain events. Additionally, it was found that, while nocturnal evaporation was negligible during dry periods, it was quite significant (up to 30 % of the daily cumulative flux) during nights following rain events. Our results further show that the highest spatial variability in surface soil moisture is found under dry conditions. Finally, we report strong spatial heterogeneities in evaporation rates following a rain event. The cumulative evaporation for the different sampling sites over a five-day period varied from ≈ 0.1 to ≈ 6.6 mm. Overall, this study allows us to better understand the mechanisms underlying soil moisture dynamics of desert playas as well as evaporation following occasional rain events.

  13. Strontium isotope geochemistry of soil and playa deposits near Yucca Mountain, Nevada

    SciTech Connect

    Marshall, B.D.; Mahan, S.A.

    1994-12-31

    The isotopic composition of strontium contained in the carbonate fractions of soils provides an excellent tracer which can be used to test models for their origin. This paper reports data on surface coatings and cements, eolian sediments, playas and alluvial fan soils which help to constrain a model for formation of the extensive calcretes and fault infilling in the Yucca Mountain region. The playas contain carbonate with a wide range of strontium compositions; further work will be required to fully understand their possible contributions to the pedogenic carbonate system. Soils from an alluvial fan to the west of Yucca Mountain show that only small amounts of strontium are derived from weathering of silicate detritus. However, calcretes from a fan draining a carbonate terrane have strontium compositions dominated locally by the limestone strontium component. Although much evidence points to an eolian source for at least some of the strontium in the pedogenic carbonates near Yucca Mountain, an additional component or past variation of strontium composition in the eolian source is required to model the pedogenic carbonate system.

  14. Sodium toxicity and pathology associated with exposure of waterfowl to hypersaline playa lakes of southeast New Mexico

    USGS Publications Warehouse

    Meteyer, C.U.; Dubielzig, R.D.; Dein, F.J.; Baeten, L.A.; Moore, M.K.; Jehl, J.R.; Wesenberg, K.E.

    1997-01-01

    Cause of mortality was studied in waterfowl in hypersaline playa lakes of southeast New Mexico during spring and fall migration. Mortality was not common in wild ducks resting on the playas during good weather. However, when birds remained on the lakes for prolonged periods of time, such as during experimental trials and stormy weather, a heavy layer of salt precipitated on their feathers. Sodium toxicity was the cause of death for all experimental mallards housed on playa water and for 50% of the wild waterfowl found moribund or dead during the spring of 1995. Gross lesions included heavy salt precipitation on the feathers, ocular lens opacities, deeply congested brains, and dilated, thin-walled, fluid-filled cloacae. Microscopic lesions in the more severely affected birds included liquefaction of ocular lens cortex with lens fiber swelling and multifocal to diffuse ulcerative conjunctivitis with severe granulocytic inflammation, edema, and granulocytic vasculitis resulting in thrombosis. Inflammation similar to that seen in the conjunctiva occasionally involved the mucosa of the mouth, pharynx, nasal turbinates, cloaca, and bursa. Transcorneal movement of water in response to the hypersaline conditions on the playa lakes or direct contact with salt crystals could induce anterior segment dehydration of the aqueous humor and increased osmotic pressure on the lens, leading to cataract formation.

  15. A hydrous Ca-bearing magnesium carbonate from playa lake sediments, Salines Lake, Spain

    USGS Publications Warehouse

    Queralt, I.; Julia, R.; Plana, F.; Bischoff, J.L.

    1997-01-01

    Sediments of playa Lake Salines, SE, Spain, contain a carbonate mineral characterized by X-ray diffraction peaks very similar to, but systematically shifted from those of pure magnesite. Analyses (SEM, IR and Raman spectroscopy, DTA, TGA, and ICP) indicate the mineral is a hydrous Ca-bearing magnesium carbonate with the chemical formula (Mg0.92,Ca0.08)CO3??3H2O. Thermal characteristics of the mineral are similar to those of other known hydrated magnesium carbonates. X-ray and electron diffraction data suggests a monoclinic system (P21/n space group) with unit-cell parameters of a = 6.063(6), b = 10.668(5), and c = 6.014(4) A?? and ?? = 107.28??.

  16. Mapping playa evaporite minerals with AVIRIS data: A first report from death valley, California

    USGS Publications Warehouse

    Crowley, J.K.

    1993-01-01

    Efflorescent salt crusts in Death Valley, California, were mapped by using Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data and a recently developed least-squares spectral band-fitting algorithm. Eight different saline minerals were remotely identified, including three borates, hydroboracite, pinnoite, and rivadavite, that have not been previously reported from the Death Valley efflorescent crusts. The three borates are locally important phases in the crusts, and at least one of the minerals, rivadavite, appears to be forming directly from brine. Borates and other evaporite minerals provide a basis for making remote chemical measurements of desert hydrologic systems. For example, in the Eagle Borax Spring area, the AVIRIS mineral maps pointed to elevated magnesium and boron levels in the ground waters, and to the action of chemical divides causing subsurface fractionation of calcium. Many other chemical aspects of playa brines should have an expression in the associated evaporite assemblages. Certain anhydrous evaporites, including anhydrite, glauberite, and thenardite, lack absorption bands in the visible and near-infrared wavelength range, and crusts composed of these minerals could not be characterized by using AVIRIS. In these situations, thermal-infrared remote sensing data may complement visible and near-infrared data for mapping evaporites. Another problem occurred in wet areas of Death Valley, where water absorption caused low signal levels in the 2.0-2.5 ??m wavelength region that obscured any spectral features of evaporite minerals. Despite these difficulties, the results of this study demonstrate the potential for using AVIRIS and other imaging spectrometer data to study playa chemistry. Such data can be useful for understanding chemical linkages between evaporites and ground waters, and will facilitate studies of how desert ground-water regimes change through time in response to climatic and other variables. ?? 1993.

  17. Sedimentology of a Permian playa lake: the Boda Claystone Formation, Hungary

    NASA Astrophysics Data System (ADS)

    Konrád, Gyula; Sebe, Krisztina; Halász, Amadé; Babinszki, Edit

    2010-04-01

    The Upper Permian Boda Claystone Formation (BCF) in SW Hungary has been previously been identified as a saline lake deposit. A country-wide screening found this 800-1000 m thick succession the most suitable for the disposal of high-level radioactive waste in Hungary, and research into this formation has consequently been intensified since. The investigations included a detailed study of the sedimentological characteristics. Data obtained by mapping of the 25 km2 outcrop area of the formation and from more than 40 boreholes were processed. The sedimentary structures were investigated on outcrop to microscopic scales, and cycles in the succession were interpreted. The main lithofacies, sedimentary structures and ichnofossils are presented. They indicate that the major part of the succession was deposited in a playa mudflat and is not of lacustrine origin in a strict sense. The lake sediments are represented by laminated and ripple-marked/flaser-type cross-laminated claystones and siltstones and by massive dolomites; trace fossils include crawling traces and burrows. Partial or complete drying out of the lake commonly occurred after the formation of carbonate mud by evaporation. Periodic fluvial influx is recorded by cross-bedded sandstones and unsorted gravelly sandstones of up to pebble-sized angular grains. Fenestral and stromatolitic structures reflect the repeated appearance of playa mudflat conditions. The silty claystones, which compose the major part of the succession, lost their primary structures due to pedogenic processes and indicate prolonged subaerial intervals with soil formation and only ephemeral inundations. The presence of pedogenic carbonate concretions supports the interpretation of an arid climate and a relatively shallow groundwater table. Drying-out events shown by desiccation cracks and authigenic breccias can be traced all over the succession. The various facies form small-scale sedimentary cycles showing a shallowing-upward trend and the

  18. Mapping playa evaporite minerals and associated sediments in Death Valley, California, with multispectral thermal infrared images

    USGS Publications Warehouse

    Crowley, J.K.; Hook, S.J.

    1996-01-01

    Efflorescent salt crusts and associated sediments in Death Valley, California, were studied with remote-sensing data acquired by the NASA thermal infrared multispectral scanner (TIMS). Nine spectral classes that represent a variety of surface materials were distinguished, including several classes that reflect important aspects of the playa groundwater chemistry and hydrology. Evaporite crusts containing abundant thenardite (sodium sulfate) were mapped along the northern and eastern margins of the Cottonball Basin, areas where the inflow waters are rich in sodium. Gypsum (calcium sulfate) crusts were more common in the Badwater Basin, particularly near springs associated with calcic groundwaters along the western basin margin. Evaporite-rich crusts generally marked areas where groundwater is periodically near the surface and thus able to replenish the crusts though capillary evaporation. Detrital silicate minerals were prevalent in other parts of the salt pan where shallow groundwater does not affect the surface composition. The surface features in Death Valley change in response to climatic variations on several different timescales. For example, salt crusts on low-lying mudflats form and redissolve during seasonal-to-interannual cycles of wetting and desiccation. In contrast, recent flooding and erosion of rough-salt surfaces in Death Valley probably reflect increased regional precipitation spanning several decades. Remote-sensing observations of playas can provide a means for monitoring changes in evaporite facies and for better understanding the associated climatic processes. At present, such studies are limited by the availability of suitable airborne scanner data. However, with the launch of the Earth Observing System (EOS) AM-1 Platform in 1998, multispectral visible/near-infrared and thermal infrared remote-sensing data will become globally available. Copyright 1996 by the American Geophysical Union.

  19. Mineralogical Composition and Potential Dust Source of Playas in the Western U.S. and Australia as Remotely Identified Through Imaging Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Raming, L. W.; Farrand, W. H.; Bowen, B.

    2015-12-01

    Playas are significant dust sources and as a result are potentially hazardous to human health. The composition of the dust is a function of the mineralogical content of the playa and associated brines. Playas are found in arid climates globally, however they are challenging to map geologically as they are often hard to access, have subtle variations in mineralogy, and are topographically featureless. This study uses remote sensing in the form of imaging spectroscopy to map the mineralogical composition of five playas from different geologic settings: Railroad Valley Playa, Nevada, USA; Bonneville Salt Flats, Utah, USA; White Sands National Monument, New Mexico, USA; Lake Brown, Western Australia, Australia; and Lake Tyrrell, Victoria, Australia.Multiple spectrometers were used for this study; these include the multispectral sensor ASTER, and the hyperspectral sensors AVIRIS, HICO, and HyMap. All scenes were processed in ENVI and corrected to at surface reflectance using FLAASH, QUAC or Empirical Line methods. Minerals were identified through a standard end-member extraction approach and mapped using multi-range spectral feature fitting and other methods. Additionally, remote data are combined with in-situ field-based spectra and sample-based laboratory spectra.Initial results suggest various and differing mineralogy between playas. The most abundant mineralogy includes clay minerals such as illite and montmorillonite and evaporites such as gypsum. Additionally there has been identification of Fe absorption bands in the visible / near infrared at White Sands National Monument, and Lake Brown and Lake Tyrell, suggesting the presence of iron bearing minerals. Further research will provide a more comprehensive list of minerals identified by absorption features as related to specific sensors. Collectively, these analyses will be used characterize overall patterns in playa surface mineralogy and to evaluate the parameters that influence playa dust source composition.

  20. Visible and near-infrared (0.4-2.5 μm) reflectance spectra of playa evaporite minerals

    USGS Publications Warehouse

    Crowley, James K.

    1991-01-01

    Visible and near-infrared (VNIR; 0.4–2.4 μm) reflectance spectra were recorded for 35 saline minerals that represent the wide range of mineral and brine chemical compositions found in playa evaporite settings. The spectra show that many of the saline minerals exhibit diagnostic near-infrared absorption bands, chiefly attributable to vibrations of hydrogen-bonded structural water molecules. VNIR reflectance spectra can be used to detect minor hydrate phases present in mixtures dominated by anhydrous halite or thenardite, and therefore will be useful in combination with X ray diffraction data for characterizing natural saline mineral assemblages. In addition, VNIR reflectance spectra are sensitive to differences in sample hydration state and should facilitate in situ studies of minerals that occur as fragile, transitory dehydration products in natural salt crusts. The use of spectral reflectance measurements in playa studies should aid in mapping evaporite mineral distributions and may provide insight into the geochemical and hydrological controls on playa mineral and brine development.

  1. Sedimentary facies and environmental ichnology of a ?Permian playa-lake complex in western Argentina

    USGS Publications Warehouse

    Zhang, G.; Buatois, L.A.; Mangano, M.G.; Acenolaza, F.G.

    1998-01-01

    A moderately diverse arthropod icnofauna occurs in ?Permian ephemeral lacustrine deposits of the Paganzo Basin that crop out at Bordo Atravesado, Cuesta de Miranda, western Argentina. Sedimentary successions are interpreted as having accumulated in a playa-lake complex. Deposits include three sedimentary facies: (A) laminated siltstone and mudstone: (B) current-rippled cross-laminated very fine grained sandstone: and (C) climbing and wave-rippled cross-laminated fine-grained sandstone deposited by sheet floods under wave influence in the playa-lake complex. Analysis of facies sequences suggests that repeated vertical facies associations result from transgressive regressive episodes of variable time spans. The Bordo Atravesado ichnofauna includes Cruziana problematica, Diplocraterion isp., cf. Diplopadichnus biformis, Kouphichnium? isp., Merostomichnites aicunai, Mirandaichnium famatinense, Monomorphichnus lineatus, Palaeophyeus tubularis, Umfolozia sinuosa and Umfolozia ef. U. longula. The assemblage is largely dominated by arthropod trackways and represents an example of the Scoyenia ichnofacies. Trace fossils are mostly preserved as hypichnial ridges on the soles of facies C beds, being comparatively rare in facies A and B. Ichnofossil preservation was linked to rapid influx of sand via sheet floods entering into the lake. Four taphonomic variants (types 1-4) are recognized, each determined by substrate consistency and time averaging. Type 1 is recorded by the presence of low density assemblages consisting of poorly defined trackways, which suggests that arthropods crawled in soft, probably slightly subaqueous substrates. Type 2 is represented by low to moderate density suites that include sharply defined trackways commonly associated with mud cracks, suggesting that the tracemakers inhabited a firm, desiccated lacustrine substrate. Type 3 displays features of types 1 and 2 and represents palimpsestic bedding surfaces, resulting from the overprint of terrestrial

  2. High Habitability Potentials Generated by Subsurface Salt Mixtures at DLT Playa on Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Wang, A.

    2015-12-01

    What is the habitability of a salty subsurface environment in a hyperarid region, where the salts are mixtures of chlorides, chloride hydrates, and hydrous sulfates? We report a new concept developed on the basis of observations on Mars, field investigations at DLT playa in Qaidam basin on Tibet Plateau, and the laboratory studies of chlorides and sulfates. The water activities maintained in a closed environment by either chlorides or by hydrous sulfates have been studied separately in laboratory. It was found that hydrous sulfates can keep high water activities (i.e., high relative humidity RH levels) in a closed environment (e.g., subsurface salty layers), and also require high RH for their deliquescence in order to generate liquid brine to support the essential functions of life form. In contrast, the deliquescence of chlorides and chloride hydrates can happen at mid-low RH levels, but an environment filled with chlorides and chloride hydrates would not provide a suitable RH range to induce their own deliquescence even with a considerable temperature (T) change, because their capability of maintaining a water activity (i.e., a RH level) in an enclosure is not a strong dependent of temperature. The coexistence of chlorides and hydrous sulfates was found by the in situ measurements of all landed missions to Mars (rovers and landers). This coexistence was also found in the subsurface of DLT playa on Tibet Plateau by a detailed mineralogy study (Laser Raman spectroscopy and XRD). In addition, microbial life at DLT was evidenced by four types of analyses. Within DLT subsurface, the highly hydrated sulfates (MgSO4.6-7H2O) would provide a suitable RH range (90-97%) for the deliquescence of co-existing chlorides (MgCl2.6H2O, KMgCl3.6H2O, NaCl, RH need to be > 33, 65, 75%) to start, which will form thin films of liquid brine at the surface of salt grains. Furthermore, we have found that the rates of deliquescence of chlorides are strong dependents of temperature. Thus a

  3. Isotopic Evidence for the Impact of Playa Water on Shallow Groundwater Flow in the Snake River Aquifer Beneath the INEEL

    NASA Astrophysics Data System (ADS)

    Conrad, M. E.; Depaolo, D. J.; Neher, E. R.

    2002-12-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) is located on the Snake River Plain in eastern Idaho. At Test Area North (TAN) on the INEEL, waste consisting of low-level radioactive isotopes, sewage and chlorinated solvents was injected into the upper aquifer through a 95 m well, resulting in a 2 km plume of TCE in the groundwater. The geology consists of fractured basalt flows separated by sedimentary interbeds. The depth to groundwater at the site is 65 m. At 120-160 m depth, a continuous interbed (the Q-R) acts as a confining layer between the upper and lower aquifer. The primary direction of flow in the Snake River Aquifer is NE to SW, but flow at TAN (as defined by the TCE plume) is perpendicular to the regional flow, starting out to the east and bending to the SE. Possible causes of this anomalous flow include injection and/or infiltration of wastewater, infiltration of water from ephemeral playa lakes (dry for the last 50 years due to agricultural diversion), or heterogeneous permeability due to subsurface geological features. Understanding this flow is critical for determining the risk factors associated with the contamination. We have measured the isotopic compositions of surface and groundwater from TAN. Water above the Q-R interbed is evaporated (δ18O values shifted up to 3‰ ). The degree of evaporation increases towards the edge of outline of the closest playa. The 87Sr/86Sr values are very uniform (0.71035+/-0.0001) and are equal to samples from the playa system. Conversely, water beneath the Q-R is not contaminated and is isotopically distinct from the water above the interbed (no evaporation, 87Sr/86Sr values >0.711). The playa water is the primary factor producing the flow patterns observed in the TAN area. Radiocarbon ages calculated from the 14C of DIC are 1800 to 2800 years BP, giving infiltration rates of 2-3 cm/yr. Given the possibility of subsurface DIC exchange with carbonates, these ages should be considered minimum

  4. An N-TIMS Br Isotopic Study of Australian Playa Lakes

    NASA Astrophysics Data System (ADS)

    Schaefer, B. F.

    2013-12-01

    Bromine possesses a chemistry broadly comparable to that of Cl and F, however its heavier mass and lower abundance results in slightly different behaviours in geochemical cycling. For example it is disproportionately enriched in sea water with respect to Cl. Br can be considered to be a 'hydrophile' element, and hence its behaviour is in governed by that of water. It possesses two isotopes 79Br (50.686%) and 81Br (49.314%). This study has developed new chemical extraction, and most significantly, new mass spectrometric protocols for Br isotopes for evaporites and waters using N-TIMS methodologies. Existing CF-IRMS methodologies offer internal precision of ~0.3‰ (1SD, [1]), whereas N-TIMS measurements of laboratory HBr and seawater standards produce external reproducibility of <0.05‰ (1SD) over an 24 month period with internal precision typically <0.03‰ (1SD) on single analyses. Australian playa lakes record variations of >5‰, comparable to that of the whole solar system. Regionality is implied on this preliminary data set whereby Lake Gairdner, which is sourced from a single, arid region lithology, is displaced from other, multi lithological sourced lakes from the same climatic zone. [1] Shouaker-Stash et al., Anal. Chem, 77; p4027-4033, 2005.

  5. Assessment of Sampling Approaches for Remote Sensing Image Classification in the Iranian Playa Margins

    NASA Astrophysics Data System (ADS)

    Kazem Alavipanah, Seyed

    There are some problems in soil salinity studies based upon remotely sensed data: 1-spectral world is full of ambiguity and therefore soil reflectance can not be attributed to a single soil property such as salinity, 2) soil surface conditions as a function of time and space is a complex phenomena, 3) vegetation with a dynamic biological nature may create some problems in the study of soil salinity. Due to these problems the first question which may arise is how to overcome or minimise these problems. In this study we hypothesised that different sources of data, well established sampling plan and optimum approach could be useful. In order to choose representative training sites in the Iranian playa margins, to define the spectral and informational classes and to overcome some problems encountered in the variation within the field, the following attempts were made: 1) Principal Component Analysis (PCA) in order: a) to determine the most important variables, b) to understand the Landsat satellite images and the most informative components, 2) the photomorphic unit (PMU) consideration and interpretation; 3) study of salt accumulation and salt distribution in the soil profile, 4) use of several forms of field data, such as geologic, geomorphologic and soil information; 6) confirmation of field data and land cover types with farmers and the members of the team. The results led us to find at suitable approaches with a high and acceptable image classification accuracy and image interpretation. KEY WORDS; Photo Morphic Unit, Pprincipal Ccomponent Analysis, Soil Salinity, Field Work, Remote Sensing

  6. Effects of agricultural tillage and sediment accumulation on emergent plant communities in playa wetlands of the U.S. High Plains.

    PubMed

    O'Connell, Jessica L; Johnson, Lacrecia A; Daniel, Dale W; McMurry, Scott T; Smith, Loren M; Haukos, David A

    2013-05-15

    Identifying community assembly filters is a primary ecological aim. The High Plains, a 30 million ha short-grass eco-region, is intensely cultivated. Cultivation disturbance, including plowing and eroded soil deposition down-slope of plowing, influences plant composition in depressional wetlands, such as playas, within croplands. We evaluated influences of wetland cultivation and sediment deposition on plant composition in playas embedded within croplands (46 plowed and 32 unplowed) and native grasslands (79) across 6 High Plains' states. Sediment accumulation ranged from 7 to 78 cm in cropland and 1 to 35 cm in grassland playas. Deeper sediments and plowing each decreased wetland plant richness, 28% and 70% respectively in cropland wetlands. Sediment depth reduced richness 37% in small grasslands playas while it increased richness 22% in larger ones, suggesting moderate disturbance increased richness when there were nearby propagule sources. Sediment depth was unrelated to species richness in plowed wetlands, probably because plowing was a strong disturbance. Plowing removed perennial plants from vegetation communities. Sediment accumulation also influenced species composition in cropland playas, e.g., probability of Eleocharis atropurpurea increased with sediment depth, while probability of Panicum capillare decreased. In grassland playas, observed lighter sediment depths did not influence species composition after accounting for wetland area. Sediment accumulation and plowing shift wetland plant communities toward annual species and decrease habitat connectivity for wetland-dependent organisms in cropland playas over 39,000 and 23,400 ha respectively. Conservation practices lessening sediment accumulation include short-grass buffer strips surrounding wetlands. Further, wetland tillage, allowed under federal agricultural conservation programs, should be eliminated.

  7. Effects of agricultural tillage and sediment accumulation on emergent plant communities in playa wetlands of the U.S. High Plains.

    PubMed

    O'Connell, Jessica L; Johnson, Lacrecia A; Daniel, Dale W; McMurry, Scott T; Smith, Loren M; Haukos, David A

    2013-05-15

    Identifying community assembly filters is a primary ecological aim. The High Plains, a 30 million ha short-grass eco-region, is intensely cultivated. Cultivation disturbance, including plowing and eroded soil deposition down-slope of plowing, influences plant composition in depressional wetlands, such as playas, within croplands. We evaluated influences of wetland cultivation and sediment deposition on plant composition in playas embedded within croplands (46 plowed and 32 unplowed) and native grasslands (79) across 6 High Plains' states. Sediment accumulation ranged from 7 to 78 cm in cropland and 1 to 35 cm in grassland playas. Deeper sediments and plowing each decreased wetland plant richness, 28% and 70% respectively in cropland wetlands. Sediment depth reduced richness 37% in small grasslands playas while it increased richness 22% in larger ones, suggesting moderate disturbance increased richness when there were nearby propagule sources. Sediment depth was unrelated to species richness in plowed wetlands, probably because plowing was a strong disturbance. Plowing removed perennial plants from vegetation communities. Sediment accumulation also influenced species composition in cropland playas, e.g., probability of Eleocharis atropurpurea increased with sediment depth, while probability of Panicum capillare decreased. In grassland playas, observed lighter sediment depths did not influence species composition after accounting for wetland area. Sediment accumulation and plowing shift wetland plant communities toward annual species and decrease habitat connectivity for wetland-dependent organisms in cropland playas over 39,000 and 23,400 ha respectively. Conservation practices lessening sediment accumulation include short-grass buffer strips surrounding wetlands. Further, wetland tillage, allowed under federal agricultural conservation programs, should be eliminated. PMID:23500104

  8. Final Scientific/ Technical Report. Playas Grid Reliability and Distributed Energy Research

    SciTech Connect

    Romero, Van; Weinkauf, Don; Khan, Mushtaq; Helgeson, Wes; Weedeward, Kevin; LeClerc, Corey; Fuierer, Paul

    2012-06-30

    found that the benefits of net metering (like savings on investments in infrastructure and on meeting state renewables requirements) outweigh the costs (like the lowered revenue to cover utility infrastructure costs). Many are eagerly awaiting a California Public Utilities Commission study due later this year, in the hopes that it will provide a relatively unbiased look at the issue. Meanwhile, some states continue to pursue virtual net metering policies. Under Colorado’s Solar Gardens Act, for example, utility customers can subscribe to power generated somewhere other than their own homes. The program allowed by that bill sold out in 30 minutes, evidence of the pent-up demand for this kind of arrangement. And California solar advocates are hoping for passage of a “shared renewables” bill in that state, which would provide for similar solar are significant in bringing solar power to the estimated 75% (likely a conservative number) of can’t put solar on our own roof. As great a resource as the sun is, when it comes to actually implementing solar or other renewables, technology advances, policy changes, bureaucratic practices, and increased energy consciousness will all have to happen to achieve a 30% by 2050 national goal. This project incorporated research activities focused on addressing each of these challenges. First, the project researchers evaluated several leading edge solar technologies by actually implementing these technologies at Playas, New Mexico, a remote town built in the 1970s by Phelps Dodge Mining Company for the company’s employees. This town was purchased by the New Mexico Institute of Mining and Technology in 2005 and converted to a training and research center. Playas is an all-electric town served by a substation about seven miles away. The town is the last user on a 240 kV utility transmission line owned by the Columbus Electric Cooperative (CEC) making it easy to isolate for experiment purposes. The New Mexico Institute of Mining and

  9. A spectral reflectance study (0.4-2.5 μm) of selected playa evaporite mineral deposits and related geochemical processes

    USGS Publications Warehouse

    Crowley, James K.

    1990-01-01

    Playa evaporite mineral deposits show major compositional variations related to differences in lithology, hydrology, and groundwater geochemistry. The use of visible and near-infrared (VNIR) spectral reflectance measurements as a technique for investigating the mineralogy of playa efflorescent crusts is examined. Samples of efflorescent crust were collected from 4 playa: Bristol Dry Lake, Saline Valley, Teels Marsh, and Rhodes Marsh--all located in eastern California and western Nevada. Laboratory and field spectral analyses coupled with X-ray diffraction analyses of the crusts yielded the following observations: VNIR spectra of unweathered salt crusts can be used to infer the general chemistry of near-surface brines; VNIR spectra are very sensitive for detecting minor hydrate mineral phases contained in mixtures with anhydrous, spectrally featureless, minerals such as halite (NaCl) and thernardite (Na2So4); borate minerals exhibit particularly strong VNIR spectral features that permit small amounts of borate to be detected in efflorescent salt crusts; remote sensing spectral measurements of playa efflorescent crusts may have applications in global studies of playa brines and minerals.

  10. The utilization of ERTS-1-generated photographs in the evaluation of the Iranian playas as potential locations for economic and engineering development. [water-borne sedimentation of playa lakes

    NASA Technical Reports Server (NTRS)

    Krinsley, D. B. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. False-color composites made from ratioed and stretched transparencies, generated from CCT's of ERTS-1, have enhanced hydrologic and morphologic differences within the playa surficial sediments. A composite of ratios 4/6, 5/7,15/61 and 4/7 using blue, red, yellow, and green, respectively, was useful in separating wet, water, and dry areas in the salt crust and for delineating smooth and rough salt where relief was less than 20 cm.

  11. Modeling aluminum-silicon chemistries and application to Australian acidic playa lakes as analogues for Mars

    NASA Astrophysics Data System (ADS)

    Marion, G. M.; Crowley, J. K.; Thomson, B. J.; Kargel, J. S.; Bridges, N. T.; Hook, S. J.; Baldridge, A.; Brown, A. J.; Ribeiro da Luz, B.; de Souza Filho, C. R.

    2009-06-01

    Recent Mars missions have stimulated considerable thinking about the surficial geochemical evolution of Mars. Among the major relevant findings are the presence in Meridiani Planum sediments of the mineral jarosite (a ferric sulfate salt) and related minerals that require formation from an acid-salt brine and oxidizing environment. Similar mineralogies have been observed in acidic saline lake sediments in Western Australia (WA), and these lakes have been proposed as analogues for acidic sedimentary environments on Mars. The prior version of the equilibrium chemical thermodynamic FREZCHEM model lacked Al and Si chemistries that are needed to appropriately model acidic aqueous geochemistries on Earth and Mars. The objectives of this work were to (1) add Al and Si chemistries to the FREZCHEM model, (2) extend these chemistries to low temperatures (<0 °C), if possible, and (3) use the reformulated model to investigate parallels in the mineral precipitation behavior of acidic Australian lakes and hypothetical Martian brines. FREZCHEM is an equilibrium chemical thermodynamic model parameterized for concentrated electrolyte solutions using the Pitzer approach for the temperature range from <-70 to 25 °C and the pressure range from 1 to 1000 bars. Aluminum chloride and sulfate mineral parameterizations were based on experimental data. Aluminum hydroxide and silicon mineral parameterizations were based on Gibbs free energy and enthalpy data. New aluminum and silicon parameterizations added 12 new aluminum/silicon minerals to this Na-K-Mg-Ca-Fe(II)-Fe(III)-Al-H-Cl-Br-SO 4-NO 3-OH-HCO 3-CO 3-CO 2-O 2-CH 4-Si-H 2O system that now contain 95 solid phases. There were similarities, differences, and uncertainties between Australian acidic, saline playa lakes and waters that likely led to the Burns formation salt accumulations on Mars. Both systems are similar in that they are dominated by (1) acidic, saline ground waters and sediments, (2) Ca and/or Mg sulfates, and (3) iron

  12. Modeling aluminum-silicon chemistries and application to Australian acidic playa lakes as analogues for Mars

    USGS Publications Warehouse

    Marion, G.M.; Crowley, J.K.; Thomson, B.J.; Kargel, J.S.; Bridges, N.T.; Hook, S.J.; Baldridge, A.; Brown, A.J.; Ribeiro da Luz, B.; de Souza, Filho C.R.

    2009-01-01

    Recent Mars missions have stimulated considerable thinking about the surficial geochemical evolution of Mars. Among the major relevant findings are the presence in Meridiani Planum sediments of the mineral jarosite (a ferric sulfate salt) and related minerals that require formation from an acid-salt brine and oxidizing environment. Similar mineralogies have been observed in acidic saline lake sediments in Western Australia (WA), and these lakes have been proposed as analogues for acidic sedimentary environments on Mars. The prior version of the equilibrium chemical thermodynamic FREZCHEM model lacked Al and Si chemistries that are needed to appropriately model acidic aqueous geochemistries on Earth and Mars. The objectives of this work were to (1) add Al and Si chemistries to the FREZCHEM model, (2) extend these chemistries to low temperatures (<0 ??C), if possible, and (3) use the reformulated model to investigate parallels in the mineral precipitation behavior of acidic Australian lakes and hypothetical Martian brines. FREZCHEM is an equilibrium chemical thermodynamic model parameterized for concentrated electrolyte solutions using the Pitzer approach for the temperature range from <-70 to 25 ??C and the pressure range from 1 to 1000 bars. Aluminum chloride and sulfate mineral parameterizations were based on experimental data. Aluminum hydroxide and silicon mineral parameterizations were based on Gibbs free energy and enthalpy data. New aluminum and silicon parameterizations added 12 new aluminum/silicon minerals to this Na-K-Mg-Ca-Fe(II)-Fe(III)-Al-H-Cl-Br-SO4-NO3-OH-HCO3-CO3-CO2-O2-CH4-Si-H2O system that now contain 95 solid phases. There were similarities, differences, and uncertainties between Australian acidic, saline playa lakes and waters that likely led to the Burns formation salt accumulations on Mars. Both systems are similar in that they are dominated by (1) acidic, saline ground waters and sediments, (2) Ca and/or Mg sulfates, and (3) iron

  13. Effects of sediment removal on vegetation communities in Rainwater Basin playa wetlands.

    PubMed

    Beas, Benjamin J; Smith, Loren M; LaGrange, Theodore G; Stutheit, Randy

    2013-10-15

    Sedimentation from cultivated agricultural land use has altered the natural hydrologic regimes of depressional wetlands in the Great Plains. These alterations can negatively affect native wetland plant communities. Our objective was to determine if restored wetlands are developing plant communities similar to reference wetland conditions following hydrologic restoration. For this study, hydrology was restored via sediment removal. Thirty-four playa wetlands in reference, restored, and agricultural condition within the Rainwater Basin Region of Nebraska were sampled in 2008 and 2009. In 2008, reference and restored wetlands had higher species richness and more native, annual, and perennial species than agricultural wetlands. Restored wetlands had similar exotic species richness compared to reference and agricultural wetlands; however, reference wetlands contained more than agricultural wetlands. Restored wetlands proportion of exotics was 3.5 and 2 times less than agricultural wetlands and reference wetlands respectively. In 2009, reference and restored wetlands had higher species richness, more perennial species, and more native species than agricultural wetlands. Restored wetlands contained a greater number and proportion of annuals than reference and agricultural wetlands. Canonical Correspondence Analysis showed that reference, restored, and agricultural wetlands are dominated by different plant species and guilds. Restored wetland plant communities do not appear to be acting as intermediates between reference and agricultural wetland conditions or on a trajectory to reach reference conditions. This may be attributed to differing seed bank communities between reference and restored wetlands, dispersal limitations of perennial plant guilds associated with reference wetland conditions, and/or management activities may be preventing restored wetlands from reaching reference status.

  14. Mapping Playa Evaporite Minerals, White Sands, New Mexico Using Landsat ETM+

    NASA Astrophysics Data System (ADS)

    Ghrefat, H. A.; Goodell, P. C.

    2002-12-01

    Evaporite minerals are the main source of several industrial and agricultural minerals important to the U.S. and world economy. Landsat ETM+ data covering the White Sands, New Mexico have been used in this study. The White Sands Dune Field, Lake Lucero, and Alkali Flat have been chosen as target sites. The study aims to determine the number of evaporite mineral endmembers that can be detected and mapped using Landsat ETM+. Furthermore, the study also aims to determine the spatial distribution of fractional abundances of evaporite mineral endmembers assuming a linear mixing model. The Minimum Noise Fraction (MNF) transform and Principal Component Analysis (PCA) were employed to determine a reduced set of noise-free spectral bands. The Pixel Purity Index (PPI) and n-D Visualization (nDV) were conducted on the reduced set of spectral bands to identify spectrally pure evaporite mineral endmembers in the image. Mineral maps of the spatial distribution and relative abundance of evaporite minerals were performed using two different algorithms: Spectral Angle Mapper (SAM) and Linear Spectral Unmixing (LSU). Four evaporite mineral endmembers have been identified using Spectral Angle Mapper. These minerals are gypsum, halite, calcite, and thenardite. The results of Linear Spectral Unmixing showed that the most common and abundant evaporite mineral in the White Sands is gypsum. The results of Spectral Angle Mapper (SAM) and Linear Spectral Unmixing (LSU) are validated by collecting field samples from different locations within the White Sands. A good match has been determined between results of Landsat ETM+ data and field and laboratory work. Mapping of playa evaporite minerals is of potential importance for the goal of saline soil characterization, regional groundwater hydrology and quality, and mineral resource development.

  15. Saline Playas on Qinghai-Tibet Plateau as Mars Analog for the Formation-Preservation of Hydrous Salts and Biosignatures

    NASA Astrophysics Data System (ADS)

    Wang, A.; Zheng, M.; Kong, F.; Sobron, P.; Mayer, D. P.

    2010-12-01

    Qinghai-Tibet (QT) Plateau has the highest average elevation on Earth (~ 4500 m, about 50-60% of atmospheric pressure at sea-level). The high elevation induces a tremendous diurnal (and seasonal) temperature swing caused by high level of solar irradiation during the day and low level of atmospheric insulation during the evening. In addition, the Himalaya mountain chain (average height >6100 m) in the south of the QT Plateau largely blocks the pathway of humid air from the Indian Ocean, and produces a Hyperarid region (Aridity Index, AI ~ 0.04), the Qaidam Basin (N32-35, E90-100) at the north edge of the QT Plateau. Climatically, the low P, T, large ΔT, high aridity, and high UV radiation all make the Qaidam basin to be one of the most similar places on Earth to Mars. Qaidam basin has the most ancient playas (up to Eocene) and the lakes with the highest salinity on QT Plateau. More importantly, Mg-sulfates appear in the evaporative salts within the most ancient playas (Da Langtang) at the northwest corner of Qaidam basin, which mark the final stage of the evaporation sequence of brines rich in K, Na, Ca, Mg, Fe, C, B, S, and Cl. The evaporation minerals in the saline playas of Qaidam basin, their alteration and preservation under hyperarid conditions can be an interesting analog for the study of Martian salts and salty regolith. We conducted a field investigation at Da Langtan playa in Qaidam basin, with combined remote sensing (ASTER on board of NASA’s Terra satellite, 1.656, 2.167, 2.209, 2.62, 2.336, 2.40 µm), in situ sensing of a portable NIR spectrometer (WIR, 1.25-2.5 µm continuous spectral range), and the laboratory analyses of collected samples from the field (ASD spectrometer, 0.4 -2.5 µm, and Laser Raman spectroscopy). The results indicate that the materials contributing the high albedo layers in playa deposits are carbonate-gypsum-bearing surface soils, salt-clay-bearing exhaumed Pleistocene deposits, dehydrated Na-sulfates, hydrous Mg

  16. Potential transport pathways of dust emanating from the playa of Ebinur Lake, Xinjiang, in arid northwest China

    NASA Astrophysics Data System (ADS)

    Ge, Yongxiao; Abuduwaili, Jilili; Ma, Long; Wu, Na; Liu, Dongwei

    2016-09-01

    In this paper, the HYSPLIT model, driven with reanalysis meteorological data from 1978 to 2013, was used to understand the potential transport characteristics of dust and salt dust emanating from the playa of Ebinur Lake in arid northwest China. Daily air parcel trajectories were computed forward for 8 days from an origin centered over Ebinur Lake at 100 m above ground level. Air parcel trajectory density plots were mapped for seven levels: 0-100 m agl., 100-500 m agl., 500-1000 m agl., 1000-1500 m agl., 1500-2000 m agl., 2000-3000 m agl., and 3000-5000 m agl. These show that potential dust transport pathways have clear seasonal differentiation. The potential transport distance of dust and salt dust is greatest in spring and summer. In autumn and winter, the potential transport of the high-density air trajectory is below 1000 m traveling a shorter distance. Potential dust transport pathways showed notifying directivity in different seasons and heights. Southeast in spring and summer, and north to northeast in autumn and winter are the two main potential transport channels of dust and salt dust. Accordingly, dust and salt dust from the playa of Ebinur Lake may influence the atmospheric processes and biogeochemical cycles of a vast region. The main area of influence of dust and salt dust is close to the source area, and will significantly accelerate the melting of snow and ice in the Tianshan Mountains. This highlights the urgent need to combine remote sensing, isotope and other methods to further research the transport characteristics of dust and salt dust from the playa of the Ebinur Lake.

  17. Mapping compositional and particle size variations across Silver Lake Playa: Relevance to analyses of Mars TIR data

    NASA Technical Reports Server (NTRS)

    Petroy, S. B.; Arvidson, Raymond E.; Kahle, A. B.

    1991-01-01

    The high spectral and spatial resolution thermal infrared (TIR) data to be acquired from the upcoming Mars Observer-Thermal Emission Spectra (TES) mission will map the composition and texture of the Martian sediments. To prepare for these data, portions of two remote sensing experiments were conducted to test procedures for extracting surface property information from TIR data. Reported here is the continuing analysis of Thermal Infrared Multispectral Scanner (TIMS) data, field emission spectra, laboratory Fourier Transform Infrared (FTIR) reflectance spectra, and field observations with respect to the physical characteristics (composition, emissivity, etc.) of Silver Lake playa in southern California.

  18. A new ranavirus isolated from Pseudacris clarkii tadpoles in playa wetlands in the southern High Plains, Texas.

    PubMed

    Torrence, Shannon M; Green, D Earl; Benson, Catherine J; Ip, Hon S; Smith, Loren M; McMurry, Scott T

    2010-06-01

    Mass die-offs of amphibian populations pose a challenging problem for conservation biologists. Ranaviruses often cause systemic infections in amphibians and, in North America, are especially virulent and lethal to larvae and metamorphs. In this paper we describe a novel ranavirus isolate as well as the first recorded occurrence of ranavirus in the southern High Plains of Texas and in associated populations of the spotted chorus frog Pseudacris clarkii. The breeding sites were playas, that is, wetlands that fill via isolated thunderstorms that can occur infrequently; thus, not every playa has water or breeding amphibians annually. We did not detect ranavirus in sympatric anurans, but other reports document ranaviruses in Pseudacris spp. elsewhere. The occurrence of multiple isolates of ranavirus in a number of Pseudacris species suggests that this genus of frogs is highly susceptible to ranaviruses and may experience exceptionally high mortality rates from infection. Thus, the virus may contribute to substantial seasonal population declines and low seasonal recruitment, with negative impacts on populations of breeding adults in successive years. PMID:20848879

  19. A new ranavirus isolated from Pseudacris clarkii tadpoles in playa wetlands in the southern High Plains, Texas.

    PubMed

    Torrence, Shannon M; Green, D Earl; Benson, Catherine J; Ip, Hon S; Smith, Loren M; McMurry, Scott T

    2010-06-01

    Mass die-offs of amphibian populations pose a challenging problem for conservation biologists. Ranaviruses often cause systemic infections in amphibians and, in North America, are especially virulent and lethal to larvae and metamorphs. In this paper we describe a novel ranavirus isolate as well as the first recorded occurrence of ranavirus in the southern High Plains of Texas and in associated populations of the spotted chorus frog Pseudacris clarkii. The breeding sites were playas, that is, wetlands that fill via isolated thunderstorms that can occur infrequently; thus, not every playa has water or breeding amphibians annually. We did not detect ranavirus in sympatric anurans, but other reports document ranaviruses in Pseudacris spp. elsewhere. The occurrence of multiple isolates of ranavirus in a number of Pseudacris species suggests that this genus of frogs is highly susceptible to ranaviruses and may experience exceptionally high mortality rates from infection. Thus, the virus may contribute to substantial seasonal population declines and low seasonal recruitment, with negative impacts on populations of breeding adults in successive years.

  20. Building on previous OSL dating techniques for gypsum: a case study from Salt Basin playa, New Mexico and Texas

    USGS Publications Warehouse

    Mahan, Shannon; Kay, John

    2012-01-01

    The long term stability and reliability of the luminescence signal for gypsum has not been well documented or systematically measured until just recently. A review of the current literature for luminescence dating of gypsum is compiled here along with original efforts at dating an intact and in-situ bed of selenite gypsum at Salt Basin Playa, New Mexico and Texas. This effort differs from other documented luminescence dating efforts because the gypsum is not powdery or redistributed from its original growth patterns within the playa basin but is instead of a crystalline form. Sixteen ages from eight cores were ultimately produced with seven of the ages coming from rare detrital quartz encased in or with the gypsum crystals while the remaining ages are from the crystalline gypsum. As far as can be ascertained, the quartz was measured separately from the gypsum and no contaminants were noted in any of the aliquots. Some basic and preliminary tests of signal stability were measured and found to be mitigated by lessening of pre-heat protocols. Ages ranged from 8 ka to 10 ka in the shallow cores and 16 ka to 22 ka in the deeper cores. These ages will be useful in determining rates of gypsum growth within a sequence of evaporates which, in turn, will help to better document historic rates of evaporation and thus estimate, with more precision, the corresponding annual evaporation rates.

  1. Reconstructing relative flooding intensities responsible for hurricane-induced deposits from Laguna Playa Grande, Vieques, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Woodruff, Jonathan D.; Donnelly, Jeffrey P.; Mohrig, David; Geyer, Wayne R.

    2008-05-01

    Extreme coastal flooding, primarily during hurricane strikes,has deposited sand-rich layers in Laguna Playa Grande, a back-barrierlagoon located on the island of Vieques, Puerto Rico. Silici-clasticgrain-size distributions within these overwash deposits finelandward (away from the barrier and toward the mainland). Asimple advective-settling model can explain this pattern oflateral sorting and is used to constrain the relative magnitudeof past flooding events. A deposit associated with the A.D.1928 San Felipe hurricane is used as a modern analogue to testthe technique, which produces reasonable estimates for waveheights that exceed the barrier during the event. A 5000 yrreconstruction of local flooding intensity is developed thatprovides a measure of the competence for each overwash eventto transport coarser-grained sediment a fixed distance intothe lagoon. This reconstruction indicates that although theLaguna Playa Grande record exhibits large-scale changes in hurricanefrequency on centennial to millennial time scales, the magnitudeof these events has stayed relatively constant. Over the last5000 yr, no evidence exists for an anomalously large hurricaneor tsunami event with a competence for sediment transport greaterthan historical hurricane events.

  2. Geologic investigation of Playa Lakes, Tonopah Test Range, Nevada : data report.

    SciTech Connect

    Rautman, Christopher Arthur

    2004-12-01

    Subsurface geological investigations have been conducted at two large playa lakes at the Tonopah Test Range in central Nevada. These characterization activities were intended to provide basic stratigraphic-framework information regarding the lateral distribution of ''hard'' and ''soft'' sedimentary materials for use in defining suitable target regions for penetration testing. Both downhole geophysical measurements and macroscopic lithilogic descriptions were used as a surrogate for quantitative mechanical-strength properties, although some quantitative laboratory strength measurements were obtained as well. Both rotary (71) and core (19) holes on a systematic grid were drilled in the southern half of the Main Lake; drill hole spacings are 300 ft north-south and 500-ft east-west. The drilled region overlaps a previous cone-penetrometer survey that also addressed the distribution of hard and soft material. Holes were drilled to a depth of 40 ft and logged using both geologic examination and down-hole geophysical surveying. The data identify a large complex of very coarse-grained sediment (clasts up to 8 mm) with interbedded finer-grained sands, silts and clays, underlying a fairly uniform layer of silty clay 6 to 12 ft thick. Geophysical densities of the course-grained materials exceed 2.0 g/cm{sup 2}, and this petrophysical value appears to be a valid discriminator of hard vs. soft sediments in the subsurface. Thirty-four holes, including both core and rotary drilling, were drilled on a portion of the much larger Antelope Lake. A set of pre-drilling geophysical surveys, including time-domain electromagnetic methods, galvanic resistivity soundings, and terrain-conductivity surveying, was used to identify the gross distribution of conductive and resistive facies with respect to the present lake outline. Conductive areas were postulated to represent softer, clay-rich sediments with larger amounts of contained conductive ground water. Initial drilling, consisting of

  3. Supply-limited horizontal sand drift at an ephemerally crusted, unvegetated saline playa

    USGS Publications Warehouse

    Gillette, Dale A.; Niemeyer, T.C.; Helm, P.J.

    2001-01-01

    A site at Owens Dry Lake was observed for more than 4 years. The site was a vegetation-free saline playa where the surface formed "ephemeral crusts," crusts that form after rainfall. Sometimes these crusts were destroyed and often a layer of particles on the crust would engage in vigorous aeolian activity. Three "phases" of active sand drifting are defined as almost no movement (extreme supply limitation), loose particles on crust with some degree of sand drift (moderate supply limitation), and unlimited source movement corresponding to a destroyed surface crust (unlimited supply). These "phases" occurred 45, 49, and 6% of the time, respectively. The accumulation of loose particles on the crust was mostly the result of in situ formation. Crusted sediments with loose particles on top can exhibit mass flux rates about the same as for noncrusted sediments. Crusted sediments limit or eliminate sand drift in two conditions: for rough crusts that effect a sufficiently high threshold friction velocity (above the wind friction velocity) and for limited amounts of loose particles on the crust where particle supply is less than would be transported in normal saltation for a thick sandy surface. These "supply-limited" cases are similar to wind erosion of limited spilled material on a hard concrete surface. We quantified "supply limitation" by defining a "potential" or "supply unlimited" sand drift function Q = AG where A represents supply limitation that decreases as the particle source is depleted. Here Q is the mass of sand transported through a surface perpendicular to the ground and to the wind and having unit width during time period t, and G = ??? u*(u*2 - u*t2) dt for u* > u*t. G is integrated for the same time period t as for Q, u* is the friction velocity of the wind, and u*t is the threshold friction velocity of the wind. Hard crusts (usually formed in the summer) tended to show almost no change of threshold friction velocity with time and often gave total

  4. Geologic and paleoseismic study of the Lavic Lake fault at Lavic Lake Playa, Mojave Desert, Southern California

    USGS Publications Warehouse

    Rymer, M.J.; Seitz, G.G.; Weaver, K.D.; Orgil, A.; Faneros, G.; Hamilton, J.C.; Goetz, C.

    2002-01-01

    Paleoseismic investigations of the Lavic Lake fault at Lavic Lake playa place constraints on the timing of a possible earlier earthquake along the 1999 Hector Mine rupture trace and reveal evidence of the timing of the penultimate earthquake on a strand of the Lavic Lake fault that did not rupture in 1999. Three of our four trenches, trenches A, B, and C, were excavated across the 1999 Hector Mine rupture; a fourth trench, D, was excavated across a vegetation lineament that had only minor slip at its southern end in 1999. Trenches A-C exposed strata that are broken only by the 1999 rupture; trench D exposed horizontal bedding that is locally warped and offset by faults. Stratigraphic evidence for the timing of an earlier earthquake along the 1999 rupture across Lavic Lake playa was not exposed. Thus, an earlier event, if there was one along that rupture trace, predates the lowest stratigraphic level exposed in our trenches. Radiocarbon dating of strata near the bottom of trenches constrains a possible earlier event to some time earlier than about 4950 B.C. Buried faults revealed in trench D are below a vegetation lineament at the ground surface. A depositional contact about 80 cm below the ground surface acts as the upward termination of fault breaks in trench D. Thus, this contact may be the event horizon for a surface-rupturing earthquake prior to 1999-the penultimate earthquake on the Lavic Lake fault. Radiocarbon ages of detrital charcoal samples from immediately below the event horizon indicate that the earthquake associated with the faulting occurred later than A.D. 260. An approximately 1300-year age difference between two samples at about the same stratigraphic level below the event horizon suggests the potential for a long residence time of detrital charcoal in the area. Coupled with a lack of bioturbation that could introduce young organic material into the stratigraphic section, the charcoal ages provide only a maximum bounding age; thus, the recognized

  5. The utilization of ERTS-1-generated photographs in the evaluation of the Iranian playas as potential locations for economic and engineering development

    NASA Technical Reports Server (NTRS)

    Krinsley, D. B. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Seasonal monitoring of hydrologic conditions at three playa lakes provides a basis for constructing an annual water inventory for these lakes. Although the extreme variation in the extent of playa lakes must be considered, the principal periods of their fluctuations are generally constant. Playa lakes provide an important water source for arid region needs, and their water can be diverted and stored for use during the long, hot, and dry summer. At their 1973 maxima, approximately 400 million cu m and 794 million cu m of water were available at the lakes at Qom and Neriz playas, respectively. These lakes adjoin areas of moderately dense population that have severe annual water deficits. A preliminary road alignment across the Great Kavir in north-central Iran has been prepared from an analysis of ERTS-1 images of that area from September 2, 1972, through May 12, 1973, a total of 6 scenes. An all-weather road constructed along this alignment could reduce the distance between points north and south of the Great Kavir by as much as 700 km.

  6. Unravelling aquifer-wetland interaction using CSAMT and gravity methods: the Mollina-Camorra aquifer and the Fuente de Piedra playa-lake, southern Spain

    NASA Astrophysics Data System (ADS)

    Pedrera, A.; Martos-Rosillo, S.; Galindo-Zaldívar, J.; Rodríguez-Rodríguez, M.; Benavente, J.; Martín-Rodríguez, J. F.; Zúñiga-López, M. I.

    2016-06-01

    The hydrological regime of Fuente de Piedra playa-lake (Málaga, southern Spain) has been significantly affected by the intensive exploitation of groundwater in the area. The playa-lake is situated above clays, marls, and gypsum, and under unaltered conditions received surface-subsurface runoff within the watershed as well as groundwater discharge from two carbonate aquifers. We have analyzed the structure of the main one, the Mollina-Camorra carbonate aquifer, by combining controlled source audio magnetotellurics (CSAMT), gravity prospecting, and time-domain electromagnetic (TDEM) soundings. This geophysical information, together with new structural and hydrogeological data, was gathered to develop a new conceptual hydrogeological model. This model allows the hydrological linkage of the carbonate aquifer with the playa-lake system to be established. Moreover, the intensive exploitation in the carbonate aquifer, even outside the watershed of the playa-lake, has affected the hydrological regime of the system. This multidisciplinary work demonstrates the potential of geophysical methods for understanding wetland-aquifer interaction, having important groundwater management implications.

  7. Impact of Diagenesis on Biosignature Preservation Potential in Playa Lake Evaporites in Verde Formation, Arizona: Implications for Mars Exploration

    NASA Astrophysics Data System (ADS)

    Shkolyar, S.; Farmer, J. D.

    2015-12-01

    Major priorities for Mars science include assessing the preservation potential and impact of diagenesis on biosignature preservation in aqueous sedimentary environments. We address these priorities with field and lab studies of playa evaporites of the Verde Formation (upper Pliocene) in Arizona. Evaporites studied include bottom-nucleated halite and displacive growth gypsum in magnesite-rich mudstone. These lithotypes are potential analogs for ancient lacustrine habitable environments on Mars. This study aimed to understand organic matter preservation potential under different diagenetic histories. Methods combined outcrop-scale field observations and lab analyses, including: (1) thin-section petrography to understand diagenetic processes and paragenesis; (2) X-ray powder diffraction to obtain bulk mineralogy; (3) Raman spectroscopy to identify and place phases (and kerogenous fossil remains) within a microtextural context; (4) Total Organic Carbon (TOC) analyses to estimate weight percentages of preserved organic carbon for each subfacies endmember; and (5) electron microprobe to create 2D kerogen maps semi-quantifying kerogen preservation in each subfacies. Results revealed complex diagenetic histories for each evaporite subfacies and pathways for organic matter preservation. Secondary gypsum grew displacively within primary playa lake mudstones during early diagenesis. Mudstones then experienced cementation by Mg-carbonates. Displacive-growth gypsum was sometimes dissolved, forming crystal molds. These molds were later either infilled by secondary sulfates or recrystallized to gypsum pseudomorphs with minor phases present (i.e., glauberite). These observations helped define taphonomic models for organic matter preservation in each subfacies. This work has the potential to inform in situ target identification, sampling strategies, and data interpretations for future Mars Sample Return missions (e.g., sample caching strategies for NASA's Mars 2020 mission).

  8. Groundwater Modeling of Playa-Focused Recharge at the Southwestern Edge of the High Plains Aquifer in West Texas

    NASA Astrophysics Data System (ADS)

    Blainey, J.; Pickens, J. F.; grisak, G. E.; Holt, R. M.; Sigda, J.; Cook, S.; Hughes, E.

    2011-12-01

    Ongoing hydrogeologic investigations at a licensed low-level radioactive waste disposal site in Andrews County, Texas include monitoring of a groundwater system in Ogallala (Neogene), Antlers (Cretaceous), and Gatuna (Neogene/Quaternary) Formation sediments on the southwestern edge of the Southern High Plains physiographic province. The disposal site is underlain by unsaturated sands and gravels of these laterally contiguous sediments, informally termed the OAG. North of the site these sediments develop into the continuously saturated High Plains or Ogallala aquifer. Episodes of focused recharge to the OAG sediments have been observed during the last 9 years of groundwater level monitoring near small playas and topographic depressions that collect water after large precipitation events. During smaller precipitation events water is stored in the unsaturated zone and evapotranspired, predominately by mesquite, creosote and grasses. The climate is semi-arid with average evaporation rates far exceeding the estimated average annual precipitation of 15-16 inches/year. Monitoring at more than 250 wells in the OAG and environmental tracer studies confirm a conceptual model of playa-focused natural recharge to the groundwater system with little or no recharge occurring in inter-playa areas. The thickness of the OAG saturated sediments in the vicinity of the disposal sites ranges from 3 feet to 10 feet, with areas of discontinuous saturation away from areas of focused recharge. Environmental tracer studies show the groundwater in the OAG is poorly mixed and disconnected from regional groundwater flow further to the northeast. The disposal facilities are located over a structural high on the erosional surface of the Dockum Group, which immediately underlies the OAG sediments. This feature, referred to as the red bed ridge, is roughly coincident with the topographic divide between the High Plains and the Pecos Valley physiographic provinces and serves as a divide for

  9. A Br Isotopic Study of Australian Arid Playa Lakes and halophyte vegetation as a monitor of Br transport

    NASA Astrophysics Data System (ADS)

    Schaefer, B. F.

    2014-12-01

    Bromine possesses a chemistry broadly comparable to that of Cl and F, however its heavier mass and lower abundance results in slightly different behaviours in geochemical cycling. For example it is disproportionately enriched in sea water with respect to Cl. Br can be considered to be a "hydrophile" element, and hence its behaviour is in governed by that of water. It possesses two isotopes 79Br (50.686%) and 81Br (49.314%). This study has developed new chemical extraction, and most significantly, new mass spectrometric protocols for Br isotopes on silicates, evaporites and waters using N-TIMS methodologies. Existing CF-IRMS methodologies offer internal precision of ~0.3‰ (1SD, [1]), whereas N-TIMS measurements of laboratory HBr and seawater standards produce external reproducibility of <0.07‰ (1SD) over an 18 month period with internal precision typically <0.06‰ (1SD) on single analyses. This study presents the first high precision, N-TIMS isotopic data on playa lake evaporites, recording a >5‰ variation in solar system 81Br/79Br. Also presented is data from the analysis of the halophylic saltbush (sp Atriplex) adjacent to the lakes to constrain biological fractionation of Br isotopes. Variations of ~4‰ are observed between the lakes with a comparable shift for the leaves of the saltbush. [1] Shouaker-Stash et al., Anal. Chem, 77; p4027-4033, 2005.

  10. Avian cholera in waterfowl: the role of lesser snow and ross's geese as disease carriers in the Playa Lakes Region.

    PubMed

    Samuel, Michael D; Shadduck, Daniel J; Goldberg, Diana R; Johnson, William P

    2005-01-01

    We collected samples from apparently healthy geese in the Playa Lakes Region (USA) during the winters of 2000-01 and 2001-02 to determine whether carriers of Pasteurella multocida, the bacterium that causes avian cholera, were present in wild populations. With the use of methods developed in laboratory challenge trials (Samuel et al., 2003a) and a serotype-specific polymerase chain reaction method for identification of P. multocida serotype 1, we found that a small proportion of 322 wild birds (<5%) were carriers of pathogenic P. multocida. On the basis of serology, an additional group of these birds (<10%) were survivors of recent avian cholera infection. Our results confirm the hypothesis that wild waterfowl are carriers of avian cholera and add support for the hypothesis that wild birds are a reservoir for this disease. In concert with other research, this work indicates that enzootic infection with avian cholera occurs in lesser snow goose (Chen caerulescens caerulescens) populations throughout their annual cycle. Although fewer Ross's geese (Chen rossii) were sampled, we also found these birds were carriers of P. multocida. Even in the absence of disease outbreaks, serologic evidence indicates that chronic disease transmission and recent infection are apparently occurring year-round in these highly gregarious birds and that a small portion of these populations are potential carriers with active infection. PMID:15827210

  11. Investigation into avian mortality in the Playa Lakes region of southeastern New Mexico: Final Report - June 1997

    USGS Publications Warehouse

    Dein, F. Joshua; Baeten, Laurie A.; Moore, Melody K.; Samuel, Michael D.; Miller, Paul D.; Murphy, Christopher; Sissler, Steven; Jeske, Clinton W.; Jehl, Joseph R.; Yaeger, J. S.; Bauer, B.; Mahoney, Shiela A.

    1997-01-01

    This Final Report is a review of work on a cooperative study undertaken by the USGS Biological Resources Division's National Wildlife Health Center (NWHC) and National Wetlands Research Center (NWRC; formerly the Southern Science Center) from 1994 through 1997. The study was initiated at the request of the Bureau of Land Management (BLM), through a request to the former National Biological Service. The Southeastern New Mexico Playa Lakes Coordinating Committee (SENMPLCC) played an important role in outlining the research needs. The initial Study Plan document, which outlines the background, objectives and methods for the first two years is available as Appendix 1. A letter indicating modifications to the Study Plan was sent to the SENMPLCC chair on April 25,1995, and is Appendix 2. An Interim Report, covering this work was completed and submitted in September 1995. The Literature Review section of the study was completed and presented to SENMPLCC in August, 1995. Following SENMPLCC review, NWHC was asked to develop a series of questions that could be posed from information gained in the initial phase (Appendix 3). The NWHC and NWRC were then directed to begin work to answer the top three questions, within the available fiscal resources. NWRC could continue with work outlined under the original Study Plan (Appendix 1), however an additional Study Plan for experiments performed by NWHC and collaborators and is available as Appendix 4.

  12. [Distribution patterns and bioerosion of the sea urchin Centrostephanus coronatus (Diadematoida: Diadematidae), at the reef of Playa Blanca, Colombian Pacific].

    PubMed

    Toro-Farmer, Gerardo; Cantera, Jaime R; Londoño-Cruz, Edgardo; Orozco, Carlos; Neira, Raul

    2004-03-01

    Regular sea-urchins are one of the main bioeroding organisms affecting coral reefs around the world. The abundance, distribution and bioerosion rate of the sea-urchin Centrostephanus coronatus, were determined in different reef zones of Playa Blanca fringing reef (Gorgona Island, Colombian pacific coast) during 1997 and 1998. The erosion rates were determined calcinating the gut content of the sea-urchins to eliminate all organic components and preserve the inorganic portion of calcium carbonate. C. coronatus showed the highest densities towards the central zones of the reef (plain-crest and front) (12.4 ind/m2; range 0-48 ind/m2). The highest mean bioerosion rate was 0.103 kgCaCO3/m2/yr in the reef plain-crest (0-0.69 kgCaCO3/m2/yr). In the other zones, (back reef and reef front) the mean bioerosion rates were 0.071 (range 0-0.39) and 0.052 (range 0-0.31) kgCaCO3/m2/yr respectively. According to the present data, it can be seen that the destruction of coralline skeletons, produced in this reef by sea-urchins is rather low, compared with the abrasion caused by these organisms in other places of the world. However, the combined action of C. coronatus and other bioeroding organisms (borers and grazers). along with some adverse environmental factors to corals, can be causing a negative balance between normal processes of reef accretion-destruction in Gorgona Island reefs.

  13. [Distribution patterns and bioerosion of the sea urchin Centrostephanus coronatus (Diadematoida: Diadematidae), at the reef of Playa Blanca, Colombian Pacific].

    PubMed

    Toro-Farmer, Gerardo; Cantera, Jaime R; Londoño-Cruz, Edgardo; Orozco, Carlos; Neira, Raul

    2004-03-01

    Regular sea-urchins are one of the main bioeroding organisms affecting coral reefs around the world. The abundance, distribution and bioerosion rate of the sea-urchin Centrostephanus coronatus, were determined in different reef zones of Playa Blanca fringing reef (Gorgona Island, Colombian pacific coast) during 1997 and 1998. The erosion rates were determined calcinating the gut content of the sea-urchins to eliminate all organic components and preserve the inorganic portion of calcium carbonate. C. coronatus showed the highest densities towards the central zones of the reef (plain-crest and front) (12.4 ind/m2; range 0-48 ind/m2). The highest mean bioerosion rate was 0.103 kgCaCO3/m2/yr in the reef plain-crest (0-0.69 kgCaCO3/m2/yr). In the other zones, (back reef and reef front) the mean bioerosion rates were 0.071 (range 0-0.39) and 0.052 (range 0-0.31) kgCaCO3/m2/yr respectively. According to the present data, it can be seen that the destruction of coralline skeletons, produced in this reef by sea-urchins is rather low, compared with the abrasion caused by these organisms in other places of the world. However, the combined action of C. coronatus and other bioeroding organisms (borers and grazers). along with some adverse environmental factors to corals, can be causing a negative balance between normal processes of reef accretion-destruction in Gorgona Island reefs. PMID:17357401

  14. Septic tanks as larval habitats for the mosquitoes Aedes aegypti and Culex quinquefasciatus in Playa-Playita, Puerto Rico.

    PubMed

    Burke, R; Barrera, R; Lewis, M; Kluchinsky, T; Claborn, D

    2010-06-01

    Adult Aedes aegypti (Linnaeus) (Diptera: Culicidae) were previously recovered from emergence traps on septic tanks in southeastern Puerto Rico. In this study we quantified immature mosquito abundance and its relationship with structural variables of the septic tanks and chemical properties of the water containing raw sewage. A miniaturized floating funnel trap was used to sample 89 septic tanks for larvae in the Puerto Rican community of Playa-Playita. Aedes aegypti larvae were recovered from 18% of the sampled tanks (10.3 larvae per septic tank per day). Larval presence was positively associated with cracking of the septic tank walls and uncovered access ports. Larval abundance was positively associated with cracking of the septic tank walls and larger tank surface areas, and inversely associated with the total dissolved solids (TDS). Culex quinquefasciatus (Say) larvae were also recovered from 74% of the septic tanks (129.6 larvae per septic tank per day). Larval presence was negatively associated with TDS in the water and larval abundance was positively associated with cracking of the septic tank walls. A screened, plastic emergence trap was used to sample 93 septic tanks within the community for Ae. aegypti and Cx. quinquefasciatus adults. Aedes aegypti adults were recovered from 49% of the sampled tanks (8.7 adults per septic tank per day) and Cx. quinquefasciatus adults were recovered from 97% of the sampled tanks (155.5 adults per septic tank per day). Aedes aegypti adult presence was positively associated with cracking, uncapped openings and septic water pH. The Ae. aegypti adult counts were positively associated with cracking and inversely associated with TDS and conductivity. This study marks the first published record of the recovery of Ae. aegypti larvae from holding tanks containing raw sewage in the Caribbean region. Our study indicates that Ae. aegypti larvae are present in sewage water and that septic tanks have at least the potential to maintain

  15. Changes in water level, land use, and hydrological budget in a semi-permanent playa lake, southwest Spain.

    PubMed

    Rodríguez-Rodríguez, M; Green, A J; López, R; Martos-Rosillo, S

    2012-01-01

    Medina playa lake, a Ramsar site in western Andalusia, is a brackish lowland lake of 120 ha with an average depth of 1 m. Water flows into Medina from its 1,748-ha watershed, but the hydrology of the lake has not previously been studied. This paper describes the application of a water budget model on a monthly scale over a 6-year period, based on a conceptual hydrological model, and considers different future scenarios after calibration to improve the understanding of the lake's hydrological functioning. Climatic variables from a nearby weather station and observational data (water-level evolution) were used to develop the model. Comparison of measured and predicted values demonstrated that each model component provided a reasonable output with a realistic interaction among the components. The model was then used to explore the potential consequences of land-use changes. Irrigation of olive groves would significantly reduce both the hydroperiod (becoming dry 15% of the time) and the average depth of the lake (water level <0.5 m 40% of the time). On the other hand, removal of an artificial overflow would double the average flooded surface area during high-water periods. The simulated water balance demonstrates that the catchment outputs are dominated by lake evaporation and surface outflow from the lake system to a creek. Discrepancies between predicted and observed water levels identify key areas of uncertainty for future empirical research. The study provides an improved basis for future hydrological management of the catchment and demonstrates the wider utility of this methodology in simulating this kind of system. This methodology provides a realistic appraisal of potential land-use management practices on a catchment-wide scale and allows predictions of the consequences of climate change.

  16. Geohydrology and evapotranspiration at Franklin Lake playa, Inyo County, California; with a section on estimating evapotranspiration using the energy-budget eddy-correlation technique

    USGS Publications Warehouse

    Czarnecki, John B.; Stannard, David I.

    1997-01-01

    Franklin Lake playa is one of the principal discharge areas of the ground-water-flow system associated with Yucca Mountain, Nevada, the potential site of a high-level nuclear-waste repository. By using the energy-budget eddy-correlation technique, measurements made between June 1983 and April 1984 to estimate evapotranspiration were found to range from 0.1 centimeter per day during winter months to about 0.3 centimeter per day during summer months; the annual average was 0.16 centimeter per day. These estimates were compared with evapotranspiration estimates calculated from six other methods.

  17. The microbiological activity and toxicity of oil-polluted playa solonchaks and filled grounds within the Severnye Buzachi Oil Field (Kazakhstan)

    NASA Astrophysics Data System (ADS)

    Tynybaeva, T. G.; Kostina, N. V.; Terekhov, A. M.; Kurakov, A. V.

    2008-10-01

    The number of colony-forming units of microorganisms, the viable biomass, and also the intensity of the microbiological processes (respiration, nitrogen fixation, denitrification, and cellulose decomposition) in playa solonchaks and sandy-loamy filled grounds in the territory of the Severnye Buzachi Oilfields (Kazakhstan) were much lower than in other soil types attesting to the limited capability of these substrates for selfpurification. Upon pollution by oil at concentrations of 100 600 mg/kg, the number of copiotrophic bacteria increased, whereas the actinomycetal and fungal populations were reduced and the biomass pool, the rates of CO2 emission, the potential nitrogen fixation, and denitrification became higher. The microbial communities of the playa solonchaks were weakly active and consumed few applied substrates. The biotesting with Artemia salina L. showed that some areas belonged to the lands of the 4th danger class, although the majority of the soil and substrate samples were not toxic. The germination of Lepidium sativum L. seeds was suppressed because of the salt toxicity, which is not related to the oil concentration (30 to 600 mg/kg).

  18. Determinacion de periodos fundamentales del suelo mediante vibraciones ambientales en el municipio de Humacao, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Cintron Aponte, Rommel

    La tecnica de Nakamura ha sido utilizada a nivel mundial para determinar periodos fundamentales del suelo. La tecnica consiste en calcular y graficar cocientes espectrales H/V de vibraciones ambientales registradas sobre el suelo. Mediciones de vibraciones ambientales fueron tomadas en 151 lugares dentro del municipio de Humacao, localizado al este de Puerto Rico. Los datos se procesaron utilizando espectros de Fourier y espectros de potencia. La tecnica fue validada al compararla con los resultados de cocientes espectrales H/V de registros de sismos debiles y tambien con una modelacion numerica realizada con datos de un ensayo "downhole". Las graficas de los cocientes espectrales H/V fueron divididas en casos y grupos, los cuales dependen de la facilidad para identificar el periodo fundamental pico y amplitudes en frecuencias menores de 1 Hz, respectivamente. Los resultados obtenidos con ambos espectros fueron comparados y se concluye que los mismos se complementan para proveer resultados mas confiables. Se crearon mapas de periodos fundamentales, factores de amplitud, isoperiodos y clasificacion sismica de sitio. Los mapas de isoperiodos fueron realizados en las zonas mas pobladas sobre depositos de suelo. El mapa de periodos fundamentales del suelo mostro buena correlacion con la geologia local. El mapa de clasificacion sismica derivado de periodos de sitio fue comparado con el mapa de clasificacion sismica derivado de barrenos geotecnicos. El mapa de clasificacion obtenido de periodos puede sobreestimar un poco algunas clasificaciones del suelo. Sin embargo, este mapa puede proveer un estimado aproximado de la velocidad de onda de corte promedio del suelo hasta una profundidad de 100 pies (30 metros).

  19. The application of remotely sensed data to pedologic and geomorphic mapping on alluvial fan and playa surfaces in Saline Valley, California

    NASA Technical Reports Server (NTRS)

    Miller, D. A.; Petersen, G. W.; Kahle, A. B.

    1986-01-01

    Arid and semiarid regions yield excellent opportunities for the study of pedologic and geomorphic processes. The dominance of rock and soil exposure over vegetation not only provides the ground observer with observational possibilities but also affords good opportunities for measurement by aircraft and satellite remote sensor devices. Previous studies conducted in the area of pedologic and geomorphic mapping in arid regions with remotely sensed data have utilized information obtained in the visible to near-infrared portion of the spectrum. Thermal Infrared Multispectral Scanner (TIMS) and Thematic Mapping (TM) data collected in 1984 are being used in comjunction with maps compiled during a Bureau of Land Management (BLM) soil survey to aid in a detailed mapping of alluvial fan and playa surfaces within the valley. The results from this study may yield valuable information concerning the application of thermal data and thermal/visible data combinations to the problem of dating pedologic and geomorphic features in arid regions.

  20. Soil-Gas Identification of Environmental Factors Affecting CO2 Concentrations Beneath a Playa Wetland: Implications for Soil-Gas Monitoring at Carbon Storage Sites

    NASA Astrophysics Data System (ADS)

    Romanak, K.; Bennett, P.

    2009-12-01

    Strategies for identifying and interpreting the effects of environmental factors on near-surface CO2 concentrations are essential to developing accurate monitoring protocols at carbon storage sites. Based on the results of a three-year study of a natural analogue we present, 1) a method for using soil-gas to identify near-surface CO2 cycling, and 2) a framework for developing monitoring protocols and site evaluation for near-surface monitoring. Near-surface CO2 production, consumption, and re-distribution was observed in the vadose-zone of a highly CO2-reactive playa wetland in the Texas High Plains. Atmospheric conditions, organic and inorganic soil carbon, subsurface pressure, water flux, and surface and groundwater chemistry were compared to real-time background measurements of CO2, CH4, O2+Ar, and N2 from depths up to 45 feet. Carbon isotopes and spatially and temporally variable concentrations of CO2 ≤ 17%, CH4 ≤ 2%, and O2 from 21-0% indicate CO2 and CH4 are produced by microbes. Molar gas ratios of O2 and CO2 distinguish between oxidation of organic matter (CH2O + O2 → CO2 + H2O), CH4 oxidation (CH4 + 2O2 → CO2 + 2H2O), and potentially acetate fermentation (CH3COOH → CH4 + CO2). O2 consumption and distribution is regulated by water flux that supplies dissolved organics to microbes at depth and regulates oxygen supply by blocking vertical permeability and atmospheric gas exchange. A surface flux experiment indicates that when playa floors are dry, subsurface wetting fronts from rain events or previous ponding periods block vertical permeability resulting in surface flux measurements that do not represent subsurface conditions. Samples with CO2+O2 < 21% and N2 > 78% identify dissolution of CO2 and carbonate minerals into recharging groundwater resulting in loss of pore pressure and chemically-induced advection of atmosphere into pores. Inverse geochemical reaction modeling (PHREEQC) of playa surface water and perched groundwater in high PCO2 zones

  1. Beach erosion and nest site selection by the leatherback sea turtle Dermochelys coriacea (Testudines: Dermochelyidae) and implications for management practices at Playa Gandoca, Costa Rica.

    PubMed

    Spanier, Matthew J

    2010-12-01

    Leatherback sea turtles (Dermochelys coriacea) nest on dynamic, erosion-prone beaches. Erosive processes and resulting nest loss have long been presumed to be a hindrance to clutch survival. In order to better understand how leatherbacks cope with unstable nesting beaches, I investigated the role of beach erosion in leatherback nest site selection at Playa Gandoca, Costa Rica. I also examined the potential effect of nest relocation, a conservation strategy in place at Playa Gandoca to prevent nest loss to erosion, on the temperature of incubating clutches. I monitored changes in beach structure as a result of erosion at natural nest sites during the time the nest was laid, as well as in subsequent weeks. To investigate slope as a cue for nest site selection, I measured the slope of the beach where turtles ascended from the sea to nest, as well as the slopes at other random locations on the beach for comparison. I examined temperature differences between natural and relocated nest sites with thermocouples placed in the sand at depths typical of leatherback nests. Nests were distributed non-randomly in a clumped distribution along the length of the beach and laid at locations that were not undergoing erosion. The slope at nest sites was significantly different than at randomly chosen locations on the beach. The sand temperature at nest depths was significantly warmer at natural nest sites than at locations of relocated nests. The findings of this study suggest leatherbacks actively select nest sites that are not undergoing erosive processes, with slope potentially being used as a cue for site selection. The relocation of nests appears to be inadvertently cooling the nest environment. Due to the fact that leatherback clutches undergo temperature-dependent sex determination, the relocation of nests may be producing an unnatural male biasing of hatchlings. The results of this study suggest that the necessity of relocation practices, largely in place to protect nests

  2. First Observation of Rock Motion on Racetrack Playa, Death Valley National Park—Role of a Persistent Pool, Sun, Zephyrs, Windowpane Ice, and Tugboats

    NASA Astrophysics Data System (ADS)

    Norris, R. D.; Norris, J. M.

    2014-12-01

    Trails in the mud-cracked surface of Racetrack Playa have been scored by hundreds of rocks up to 320 kg, but the mechanism of movement is debated. In Winter 2013-2014, we observed rocks in motion associated with a transient pool formed by winter precipitation. The pond was 7 cm deep on the southern edge of the playa, tapering to a mud flat to the north. Freezing during cold winter nights formed floating "windowpane" ice 3-5 mm thick. Rocks repeatedly moved on sunny days under light winds of 3-5 m/second, as the ice broke up near midday and was set into motion by wind stress on melt pools and the ice surface. Ice panels shoved rocks along the mud like a tugboat, sometimes forming moving imbricated ice piles upstream of the rocks and in other cases moving faster than the rocks and forming brash-filled leads downstream. GPS units mounted in experimental rocks recorded a creeping pace of 2-6 m/minute, a speed that made it difficult to observe trail formation visually. The 2013-2014 pond formed on November 20-24 and persisted through early February 2014. During this time rocks were observed moving at least five times, and studies of "stiz marks" formed by rocks at the ends of trail segments show that there were likely 3-5 additional move events. Observed travel times ranged from a few seconds to 16 minutes. In one event, two experimental rocks 153 m apart began moving simultaneously and traveled 64.1 and 65.6 m respectively, ultimately moving 157-162 m in subsequent events. Rock motion depends on the creation of winter pools sufficiently deep to allow the formation of floating ice and exposed to the light winds and sun needed for ice breakup. The combination of these events is extremely rare, leading to highly episodic trail formation. Our observations differ from previous hypotheses in that the rocks were moved by thinner ice, at slower speeds, and by lighter winds than predicted.

  3. Beach erosion and nest site selection by the leatherback sea turtle Dermochelys coriacea (Testudines: Dermochelyidae) and implications for management practices at Playa Gandoca, Costa Rica.

    PubMed

    Spanier, Matthew J

    2010-12-01

    Leatherback sea turtles (Dermochelys coriacea) nest on dynamic, erosion-prone beaches. Erosive processes and resulting nest loss have long been presumed to be a hindrance to clutch survival. In order to better understand how leatherbacks cope with unstable nesting beaches, I investigated the role of beach erosion in leatherback nest site selection at Playa Gandoca, Costa Rica. I also examined the potential effect of nest relocation, a conservation strategy in place at Playa Gandoca to prevent nest loss to erosion, on the temperature of incubating clutches. I monitored changes in beach structure as a result of erosion at natural nest sites during the time the nest was laid, as well as in subsequent weeks. To investigate slope as a cue for nest site selection, I measured the slope of the beach where turtles ascended from the sea to nest, as well as the slopes at other random locations on the beach for comparison. I examined temperature differences between natural and relocated nest sites with thermocouples placed in the sand at depths typical of leatherback nests. Nests were distributed non-randomly in a clumped distribution along the length of the beach and laid at locations that were not undergoing erosion. The slope at nest sites was significantly different than at randomly chosen locations on the beach. The sand temperature at nest depths was significantly warmer at natural nest sites than at locations of relocated nests. The findings of this study suggest leatherbacks actively select nest sites that are not undergoing erosive processes, with slope potentially being used as a cue for site selection. The relocation of nests appears to be inadvertently cooling the nest environment. Due to the fact that leatherback clutches undergo temperature-dependent sex determination, the relocation of nests may be producing an unnatural male biasing of hatchlings. The results of this study suggest that the necessity of relocation practices, largely in place to protect nests

  4. Development of a new platform for airborne measurements of atmospheric CO2 and CH4 and comparison with GOSAT measurements at Railroad Valley playa, Nevada

    NASA Astrophysics Data System (ADS)

    Tadic, J.; Loewenstein, M.; Iraci, L. T.; Gore, W.; Schiro, K. A.; Olson, R. A.; Sheffner, E. J.; Yates, E. L.

    2011-12-01

    Measurements of carbon dioxide (CO2) play an important role in understanding the global carbon cycle and its contribution to global warming. In recent years methane (CH4) has received increasing attention as the second most important anthropogenic greenhouse gas because of the high uncertainty of its sources and sinks. Aircraft measurements of greenhouse gases are essential for observations in the free troposphere and lower stratosphere to better understand changes at regional and continental scales. Recently new types of high-accuracy analyzers based on cavity-ring down spectroscopy have become available for use on aircraft. One of them, Picarro 2301-m, was remodeled and adapted for use outside the cabin of an Alpha Jet. In this unique attempt, the instrument was redesigned from a single unit to multiple units that fit inside the Alpha jet wing pod, with special emphasis on internal thermal management. After remodeling, the platform was tested in a laboratory, in a chamber with variable pressure and temperature, and in the field. This newly developed platform exhibits several important characteristics: the modular structure of the platform allows usage of other instruments simultaneously, the platform is capable of measuring both vertical and horizontal profiles of CO2 and CH4, and it is very insensitive to flight maneuvers. The new platform was used on 22-26th of June, 2011, to create spatial and temporal profiles of CO2 and CH4 over a playa in Railroad Valley, Nevada, USA. The playa is a flat, dry lakebed with virtually no vegetation, approximately 15 km x 15 km in size, 1434 m in elevation and 110 km southwest of the nearest city (Ely, Nevada). The time and location of flights were selected to coincide with the overpass of Greenhouse Gases Observing Satellite (GOSAT). Airborne (Alpha Jet) in-situ measurements of CO2 and CH4 were collected to support the vicarious calibration experiment to validate column-averaged dry air mole fractions of CO2 and CH4 (XCO2 and

  5. Avian cholera in waterfowl: the role of lesser snow and Ross's geese as carriers of avian cholera in the Playa Lakes region

    USGS Publications Warehouse

    Samuel, M.D.; Shadduck, D.J.; Goldberg, D.R.; Johnson, W.P.

    2005-01-01

    We collected samples from apparently healthy geese in the Playa Lakes Region (USA) during the winters of 2000a??01 and 2001a??02 to determine whether carriers of Pasteurella multocida, the bacterium that causes avian cholera, were present in wild populations. With the use of methods developed in laboratory challenge trials (Samuel et al., 2003a) and a serotype-specific polymerase chain reaction method for identification of P. multocida serotype 1, we found that a small proportion of 322 wild birds (<5%) were carriers of pathogenic P. multocida. On the basis of serology, an additional group of these birds (<10%) were survivors of recent avian cholera infection. Our results confirm the hypothesis that wild waterfowl are carriers of avian cholera and add support for the hypothesis that wild birds are a reservoir for this disease. In concert with other research, this work indicates that enzootic infection with avian cholera occurs in lesser snow goose (Chen caerulescens caerulescens) populations throughout their annual cycle. Although fewer Rossa??s geese (Chen rossii) were sampled, we also found these birds were carriers of P. multocida. Even in the absence of disease outbreaks, serologic evidence indicates that chronic disease transmission and recent infection are apparently occurring year-round in these highly gregarious birds and that a small portion of these populations are potential carriers with active infection.

  6. [Chemical and nutritional composition in the marine snail Strombus gracilior (Mesogastropoda: Strombidae) of various sizes and sexes in Playa Panamá, Costa Rica].

    PubMed

    Jiménez-Arce, G

    1993-12-01

    74 individuals of "cambute" (Strombus gracilior), were collected in Playa Panamá (10 degrees 35' 45"N, 85 degrees 40' 09" W), Costa Rica. The sex ratio was 1:1 and the size range 70-80mm (total length). The yield was 80% of edible meat. The average values of the macroconstituents to both sizes were: water 72.6% males and 70.9% females; 19.09g% protein in males and 26.89g% in females; carbohydrates 1.85g% males and 1.35g% females; 0.44g% crude fiber both males and females; within ashes there wre variations (2.30-3.71g%) among size and sex. Fat reached a maximum value of 0.94 and 0.91g% (length 80mm) for males and females respectively. In minerals, maximum values for the Na and K of 1440.88 and 1898.33 micrograms/g respectively were obtained for 80mm males; females of the same size showed values of 1376.97 micrograms/g for the Na and of 2393.09 micrograms/g for K; the other minerals (Cu, Mg, Fe) had lower values in relation to the above but the normal according to the literature. PMID:7701073

  7. Use RUSLE2 model to assess the impact of soil erosion on playa inundation and hydrophyte conditions in the Rainwater Basin, Nebraska.

    PubMed

    Tang, Zhenghong; Gu, Yue; Jiang, Weiguo; Xue, Yuan; Bishop, Andy; LaGrange, Ted; Nugent, Eleanor

    2016-06-01

    Playas in the Rainwater Basin region in Nebraska are globally important wetlands that are continuously threatened by culturally accelerated sedimentation. Using annual habitat survey data and wetland vegetation inventories, inundation and hydrophyte community distributions were evaluated for properties under different types of conservation status. Annual soil erosion rates from surrounding watersheds were calculated to estimate sediment accumulated rates using the Revised Universal Soil Loss Equation 2 (RUSLE2). The slope-length component of the RUSLE2 was derived from 2009 light detection and ranging (LiDAR) data after the methods described by Van Remortel (Computers & Geosciences 30:1043-1053, 2004). Wetlands enrolled in conservation programs were inundated more and were dominated to a greater degree by hydrophytes than wetlands not enrolled in these programs. The mean estimated soil erosion rate at the Rainwater Basin landscape level was 4.67 tons/ha/year, and the mean estimated sediment accumulation depth for public watersheds was estimated as 0.19 cm/year. Without appropriate conservation actions, the current inundated acres and wetland acres growing hydrophytes would be further reduced by sediment accumulation. The results illustrated the importance of conservation programs to protect wetlands. PMID:27138004

  8. Use RUSLE2 model to assess the impact of soil erosion on playa inundation and hydrophyte conditions in the Rainwater Basin, Nebraska.

    PubMed

    Tang, Zhenghong; Gu, Yue; Jiang, Weiguo; Xue, Yuan; Bishop, Andy; LaGrange, Ted; Nugent, Eleanor

    2016-06-01

    Playas in the Rainwater Basin region in Nebraska are globally important wetlands that are continuously threatened by culturally accelerated sedimentation. Using annual habitat survey data and wetland vegetation inventories, inundation and hydrophyte community distributions were evaluated for properties under different types of conservation status. Annual soil erosion rates from surrounding watersheds were calculated to estimate sediment accumulated rates using the Revised Universal Soil Loss Equation 2 (RUSLE2). The slope-length component of the RUSLE2 was derived from 2009 light detection and ranging (LiDAR) data after the methods described by Van Remortel (Computers & Geosciences 30:1043-1053, 2004). Wetlands enrolled in conservation programs were inundated more and were dominated to a greater degree by hydrophytes than wetlands not enrolled in these programs. The mean estimated soil erosion rate at the Rainwater Basin landscape level was 4.67 tons/ha/year, and the mean estimated sediment accumulation depth for public watersheds was estimated as 0.19 cm/year. Without appropriate conservation actions, the current inundated acres and wetland acres growing hydrophytes would be further reduced by sediment accumulation. The results illustrated the importance of conservation programs to protect wetlands.

  9. Physical, chemical, and mineralogical data from surficial deposits, groundwater levels, and water composition in the area of Franklin Lake playa and Ash Meadows, California and Nevada

    USGS Publications Warehouse

    Goldstein, Harland L.; Breit, George N.; Yount, James C.; Reynolds, Richard L.; Reheis, Marith C.; Skipp, Gary L.; Fisher, Eric M.; Lamothe, Paul J.

    2011-01-01

    This report presents data and describes the methods used to determine the physical attributes, as well as the chemical and mineralogical composition of surficial deposits; groundwater levels; and water composition in the area of Franklin Lake playa and Ash Meadows, California and Nevada. The results support studies that examine (1) the interaction between groundwater and the ground surface, and the transport of solutes through the unsaturated zone; (2) the potential for the accumulation of metals and metalloids in surface crusts; (3) emission of dust from metal-rich salt crust; and (4) the effects of metal-rich dusts on human and ecosystem health. The evaporation of shallow (<3 to 4 m) groundwater in saline, arid environments commonly results in the accumulation of salt in the subsurface and (or) the formation of salt crusts at the ground surface. Ground-surface characteristics such as hardness, electrical conductivity, and mineralogy depend on the types and forms of these salt crusts. In the study area, salt crusts range from hard and bedded to soft and loose (Reynolds and others, 2009). Depending on various factors such as the depth and composition of groundwater and sediment characteristics of the unsaturated zone, salt crusts may accumulate relatively high contents of trace elements. Soft, loose salt crusts are highly vulnerable to wind erosion and transport. These vulnerable crusts, which may contain high contents of potentially toxic trace elements, can travel as atmospheric dust and affect human and ecosystem health at local to regional scales.

  10. Braidplain, floodplain and playa lake, alluvial-fan, aeolian and palaeosol facies composing a diversified lithogenetical sequence in the permian and triassic of South Devon (England)

    NASA Astrophysics Data System (ADS)

    Mader, Detlef

    The Permian and Triassic of South Devon (England) are a continental red bed sequence of very diversified lithogenetical composition. Within the thick series, the distribution of the main depositional environments being fluvial braidplain, fluvial floodplain and playa lake, alluvial fan, aeolian dune and calcrete palaeosol changes repeatedly in both horizontal and vertical direction. Significant sedimentary milieus such as aeolian dunes and calcrete palaeosols occur repeatedly within the succession, but are also lacking in several parts of the sequence. Fluvial braidplain deposits comprise conglomerates, sandstones, intraformational reworking horizons and mudstones and originate in channels and overbank plains of a braided river system. Conglomerates and sandstones are formed by migration of bars and spreading out of sheets during infilling of streams and aggradation of flats. Gravel is often enriched as lag pockets or veneers within steeper scour holes and kolk pots or on the plane floor of the watercourse. Finer-grained sandstones and mudstones are laid down by suspension settling in stagnant water bodies such as small lakes in the overbank area and residual pools in interbar depressions during low-stage or waning-flow in active channels or in abandoned streams. Spectacular bioturbation features in some sandstones with both horizontal tubes and vertical burrows testify to the colonization of the sediments at the bottom of the rivers with declining discharge and transport capacity. Intraformational reworking horizons with ghost-like remnants of degraded sandstones, mudstones and pedogenic carbonates document partially severe condensation of the sequence by removal of some facies elements from the depositional record. The occasionally occurring gravel-bearing mudstones or silty-clayey sandstones represent products of high-energy water surges overspilling the channel banks and transporting sandy and gravelly bed-load in limited amounts beyond the levee wall. The

  11. Surface-water, water-quality, and ground-water assessment of the Municipio of Comerio, Puerto Rico, 1997-99

    USGS Publications Warehouse

    Rodríguez-Martínez, Jesús; Gómez-Gómez, Fernando; Santiago-Rivera, Luis; Oliveras-Feliciano, M. L.

    2001-01-01

    To meet the increasing need for a safe and adequate supply of water in the municipio of Comerio, an integrated surface-water, water-quality, and ground-water assessment of the area was conducted. The major results of this study and other important hydrologic and water-quality features were compiled in a Geographic Information System, and are presented in two 1:30,000-scale map plates to facilitate interpretation and use of the diverse water-resource data. Because the supply of safe drinking water was a critical issue during recent dry periods, the surface-water assessment portion of this study focused on analysis of low-flow characteristics in local streams and rivers. Low-flow characteristics were evaluated at one continuous-record gaging station based on graphical curve-fitting techniques and log-Pearson Type III frequency curves. Estimates of low-flow characteristics for 13 partial-record stations were generated using graphical-correlation techniques. Flow-duration characteristics for the continuous- and partial-record stations were estimated using the relation curves developed for the low-flow study. Stream low-flow statistics document the general hydrology under current land- and water-use conditions. A sanitary quality survey of streams utilized 24 sampling stations to evaluate about 84 miles of stream channels with drainage to or within the municipio of Comerio. River and stream samples for fecal coliform and fecal streptococcus analyses were collected on two occasions at base-flow conditions to evaluate the sanitary quality of streams. Bacteriological analyses indicate that about 27 miles of stream reaches within the municipio of Comerio may have fecal coliform bacteria concentrations above the water-quality goal established by the Puerto Rico Environmental Quality Board (Junta de Calidad Ambiental de Puerto Rico) for inland surface waters. Sources of fecal contamination may include illegal discharge of sewage to storm-water drains, malfunction of sanitary

  12. Surface-water, water-quality, and ground-water assessment of the Municipio of Carolina, Puerto Rico, 1997-99

    USGS Publications Warehouse

    Rodríguez-Martínez, Jesús; Gómez-Gómez, Fernando; Santiago-Rivera, Luis; Oliveras-Feliciano, M. L.

    2001-01-01

    To meet the increasing need for a safe and adequate supply of water in the municipio of Carolina, an integrated surface-water, water-quality, and ground-water assessment of the area was conducted. The major results of this study and other important hydrologic and water-quality features were compiled in a Geographic Information System and are presented in two 1:30,000-scale map plates to facilitate interpretation and use of the diverse water-resources data. Because the supply of safe drinking water was a critical issue during recent dry periods, the surface-water assessment portion of this study focused on analysis of low-flow characteristics in local streams and rivers. Low-flow characteristics were evaluated for one continuous-record gaging station, based on graphical curve-fitting techniques and log-Pearson Type III frequency analysis. Estimates of low-flow characteristics for seven partial-record stations were generated using graphical-correlation techniques. Flow-duration characteristics were computed for the one continuous-record gaging station and were estimated for the partial-record stations using the relation curves developed from the low-flow study. Stream low-flow statistics document the general hydrology under current land and water use. Low-flow statistics may substantially change as a result of streamflow diversions for public supply, and an increase in ground-water development, waste-water discharges, and flood-control measures; the current analysis provides baseline information to evaluate these impacts and develop water budgets. A sanitary quality survey of streams utilized 29 sampling stations to evaluate the sanitary quality of about 87 miles of stream channels. River and stream samples were collected on two occasions during base-flow conditions and were analyzed for fecal coliform and fecal streptococcus. Bacteriological analyses indicate that a significant portion of the stream reaches within the municipio of Carolina may have fecal coliform

  13. Cross-calibration of the Terra MODIS, Landsat 7 ETM+ and EO-1 ALI sensors using near-simultaneous surface observation over the Railroad Valley Playa, Nevada, test site

    USGS Publications Warehouse

    Chander, G.; Angal, A.; Choi, T.; Meyer, D.J.; Xiong, X.; Teillet, P.M.

    2007-01-01

    A cross-calibration methodology has been developed using coincident image pairs from the Terra Moderate Resolution Imaging Spectroradiometer (MODIS), the Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) and the Earth Observing EO-1 Advanced Land Imager (ALI) to verify the absolute radiometric calibration accuracy of these sensors with respect to each other. To quantify the effects due to different spectral responses, the Relative Spectral Responses (RSR) of these sensors were studied and compared by developing a set of "figures-of-merit." Seven cloud-free scenes collected over the Railroad Valley Playa, Nevada (RVPN), test site were used to conduct the cross-calibration study. This cross-calibration approach was based on image statistics from near-simultaneous observations made by different satellite sensors. Homogeneous regions of interest (ROI) were selected in the image pairs, and the mean target statistics were converted to absolute units of at-sensor reflectance. Using these reflectances, a set of cross-calibration equations were developed giving a relative gain and bias between the sensor pair.

  14. Surface-Water, Water-Quality, and Ground-Water Assessment of the Municipio of Mayaguez, Puerto Rico, 1999-2002

    USGS Publications Warehouse

    Rodríguez-Martínez, Jesús; Santiago-Rivera, Luis; Guzman-Rios, Senen; Gómez-Gómez, Fernando; Oliveras-Feliciano, Mario L.

    2004-01-01

    The surface-water assessment portion of this study focused on analysis of low-flow characteristics in local streams and rivers, because the supply of safe drinking water was a critical issue during recent dry periods. Low-flow characteristics were evaluated at one continuous-record gaging station based on graphical curve-fitting techniques and log-Pearson Type III frequency curves. Estimates of low-flow characteristics for 20 partial-record stations were generated using graphical-correlation techniques. Flow-duration characteristics for the continuous- and partial-record stations were estimated using the relation curves developed for the low-flow study. Stream low-flow statistics document the general hydrology under current land use, water-use, and climatic conditions. A survey of streams and rivers utilized 37 sampling stations to evaluate the sanitary quality of about 165 miles of stream channels. River and stream samples for fecal coliform and fecal streptococcus analyses were collected on two occasions at base-flow conditions. Bacteriological analyses indicate that a significant portion of the stream reaches within the municipio of Mayaguez may have fecal coliform bacteria concentrations above the water-quality goal (standard) established by the Puerto Rico Environmental Quality Board (Junta de Calidad Ambiental de Puerto Rico) for inland surface waters. Sources of fecal contamination may include: illegal discharge of sewage to storm-water drains, malfunctioning sanitary sewer ejectors, clogged and leaking sewage pipes, septic tank leakage, unfenced livestock, and runoff from livestock pens. Long-term fecal coliform data from five sampling stations located within or in the vicinity of the municipio of Mayaguez have been in compliance with the water-quality goal for fecal coliform concentration established in July 1990. Geologic, topographic, soil, hydrogeologic, and streamflow data were compiled into a database and used to divide the municipio of Mayaguez into

  15. 40 CFR 81.355 - Puerto Rico.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Adjuntas Municipio Aguada Municipio Aguadilla Municipio Aguas Buenas Municipio Aibonito Municipio Anasco... Aguada Municipio Aguadilla Municipio Aguas Buenas Municipio Aibonito Municipio Anasco Municipio Arecibo... Municipio Aguas Buenas Municipio Aibonito Municipio Añasco Municipio Arecibo Municipio Arroyo...

  16. 40 CFR 81.355 - Puerto Rico.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Adjuntas Municipio Aguada Municipio Aguadilla Municipio Aguas Buenas Municipio Aibonito Municipio Anasco... Aguada Municipio Aguadilla Municipio Aguas Buenas Municipio Aibonito Municipio Anasco Municipio Arecibo... Municipio Aguas Buenas Municipio Aibonito Municipio Añasco Municipio Arecibo Municipio Arroyo...

  17. 40 CFR 81.355 - Puerto Rico.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Adjuntas Municipio Aguada Municipio Aguadilla Municipio Aguas Buenas Municipio Aibonito Municipio Anasco... Aguada Municipio Aguadilla Municipio Aguas Buenas Municipio Aibonito Municipio Anasco Municipio Arecibo.... Aguadilla Municipio Unclassifiable/Attainment. Aguas Buenas Municipio Unclassifiable/Attainment....

  18. 40 CFR 81.355 - Puerto Rico.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Adjuntas Municipio Aguada Municipio Aguadilla Municipio Aguas Buenas Municipio Aibonito Municipio Anasco... Aguada Municipio Aguadilla Municipio Aguas Buenas Municipio Aibonito Municipio Anasco Municipio Arecibo.... Aguadilla Municipio Unclassifiable/Attainment. Aguas Buenas Municipio Unclassifiable/Attainment....

  19. 40 CFR 81.355 - Puerto Rico.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Statewide Unclassifiable/Attainment Adjuntas Municipio Aguada Municipio Aguadilla Municipio Aguas Buenas.../Attainment Adjuntas Municipio Aguada Municipio Aguadilla Municipio Aguas Buenas Municipio Aibonito Municipio... Unclassifiable/Attainment. Aguadilla Municipio Unclassifiable/Attainment. Aguas Buenas Municipio...

  20. Herbert Marcuse's Theory of Play--A Social Philosophical Perspective.

    ERIC Educational Resources Information Center

    Volkwien, Karin A. E.

    Sport has been widely discussed, by conservatives who argue that sport operates within the realm of freedom, and so lies outside the deterministic nexus of capitalist economics and policies, and leftists who argue that sport reproduces the repressive features of capitalism and serves as an ideological tool of the latter. The purpose of this study…

  1. Dynamics of playa lakes in the Texas High Plains

    NASA Technical Reports Server (NTRS)

    Reeves, C. C., Jr.

    1973-01-01

    This study shows that satellite imagery can be used for a census of the thousands of lake basins which commonly exist in semi-arid areas, and which sporadically contain water at various times of the year. Storm paths and runoff collected by such lake basins can also be closely monitored, the accuracy dependent on periodicity of the orbits and the size of the basins. Study of the relationships between spectral differences (obtained from ERTS-1 imagery) and the water balance ecosystem of the lake basins is in a preliminary stage. However, examination of ERTS-1 MSS frames show that Band 4 has the poorest tonal contrast in semi-arid West Texas, Band 5 is best for definition of vegetation, Band 6 is best for defining larger water areas, and Band 7 is best for counting small lake basins with water. Ground-truth studies reveal significant differences between test sites, the relative importance of which will be reflected by the hydrologic balance of each lake basin.

  2. Dynamics of playa lakes in the Texas High Plains

    NASA Technical Reports Server (NTRS)

    Reeves, C. C., Jr. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. ERTS-1 MSS imagery has been found useful for taking a regional wet census of the tens of thousands of lake basins on the Southern High Plains, Texas and New Mexico. Once the ground truth which has been correlated with the MSS imagery, is correlated with CCT data, and reliable computer classifications are determined, a lake census from CCT printouts will be possible. Correlation of satellite imagery products with water fluctuations and water budget is also underway.

  3. Dynamics of playa lakes in the Texas High Plains

    NASA Technical Reports Server (NTRS)

    Reeves, C. C., Jr. (Principal Investigator)

    1972-01-01

    The author has identified the following significant results. Regional viewing of ERTS-1 imagery around the test sites shows that storm paths can be accurately traced and a count made of the number of intermittent lake basins filled by the storm. Therefore, during wet years ERTS-type imagery can be used to conduct a reliable count of the tens of thousands of natural lake basins on the southern High Plains which contain water. This type of regional overview of water filled basins in the normally arid southern High Plains is illustrated by bands 6 and 7, ERTS E-1078-16524.

  4. Probabilistic flood forecasting tool for Andalusia (Spain). Application to September 2012 disaster event in Vera Playa.

    NASA Astrophysics Data System (ADS)

    García, Darío; Baquerizo, Asunción; Ortega, Miguel; Herrero, Javier; Ángel Losada, Miguel

    2013-04-01

    Torrential and heavy rains are frequent in Andalusia (Southern Spain) due to the characteristic Mediterranean climate (semi-arid areas). This, in combination with a massive occupation of floodable (river sides) and coastal areas, produces severe problems of management and damage to the population and social and economical activities when extreme events occur. Some of the most important problems are being produced during last years in Almería (Southeastern Andalusia). Between 27 and 28 September 2012 rainstorms characterized by 240mm in 24h (exceeding precipitation for a return period of 500 years) occurred. Antas River and Jático creek, that are normally dry, became raging torrents. The massive flooding of occupied areas resulted in eleven deaths and two missing in Andalucía, with a total estimated cost of all claims for compensation on the order of 197 million euros. This study presents a probabilistic flood forecasting tool including the effect of river and marine forcings. It is based on a distributed, physically-based hydrological model (WiMMed). For Almería the model has been calibrated with the largest event recorded in Cantoria gauging station (data since 1965) on 19 October 1973. It was then validated with the second strongest event (26 October 1977). Among the different results of the model, it can provide probability floods scenarios in Andalusia with up 10 days weather forecasts. The tool has been applied to Vera, a 15.000 inhabitants town located in the east of Almería along the Antas River at an altitude of 95 meters. Its main economic resource is the "beach and sun" based-tourism, which has experienced an enormous growth during last decades. Its coastal stretch has been completely built in these years, occupying floodable areas and constricting the channel and rivers mouths. Simulations of the model in this area for the 1973 event and published in March 2011 on the internet event already announced that the floods of September 2012 may occur.

  5. Play--A Multi-Modal Manifestation in Kindergarten Education in China

    ERIC Educational Resources Information Center

    Vong, Keang-Ieng

    2012-01-01

    Play, as an educational concept, has entered many kindergartens in China; yet it has not become a core idea, or been prioritised in the teaching and learning process. An ongoing trans-provincial study started in 2008, using observation, interviews and document analyses. Based on findings from nine kindergartens in three provinces, this article…

  6. The Sign Told Me how to Play--A Lesson in Risk Reduction.

    ERIC Educational Resources Information Center

    Wallach, Frances

    1988-01-01

    Two constantly appearing claims in most playground accident suits are improper supervision and lack of warning to the users. This article discusses legal implications of improper signage, explains use of symbols, and presents general sign guidelines to ensure proper safety measures. (MLH)

  7. Self-Esteem through Play--A Natural for Special Children.

    ERIC Educational Resources Information Center

    Shriver, Eunice Kennedy

    1984-01-01

    Let's Play to Grow, a club for families with handicapped children, helps special children develop social and recreational skills. Special families meet monthly to learn how to enjoy and accept themselves. Parents develop relationships with other families with similiar problems. (DF)

  8. What We Know about Play--A Walk through Selected Research.

    ERIC Educational Resources Information Center

    Oliver, Susan J.; Klugman, Edgar

    2002-01-01

    Describes the "Playing for Keeps" project of maintaining a comprehensive, categorized database summarizing current knowledge on play. Presents selected findings and information about: child development theories, studies about the developmental benefits of play, investigations into why play is useful for children, and documentation of the impact of…

  9. Australian Acid Playa Lake as a Mars Analog: Results from Sediment Lipid Analysis

    NASA Astrophysics Data System (ADS)

    Graham, H.; Baldridge, A. M.; Stern, J. C.

    2015-12-01

    The ephemeral saline acidic lakes on the Yilgarn Craton of Western Australia have been suggested as geochemical analogues to martian terrains. Both are characterized by interbedded phyllosilicates and hydrated sulfates. On Mars, these areas indicate shifting environmental conditions, from the neutral/alkaline and wet conditions that dominated during the Noachian era to the more familiar dry, acidic conditions that began in the Hesperian. The habitability of such a dynamic environment can be informed by investigation of the Yilgarn Lake system. Previous work has found phospholipid fatty acids (PLFA) evidence of microbial communities in sections of sediment cores taken from Lake Gilmore. These communities include both Gram-positive and -negative bacteria, Actinomycetes, and even methanotrophs. Given recurring detection of methane on the martian surface, evidence of a methane cycling community in an analogous environment is of particular interest. In this study we analyze the carbon isotope composition of bulk organic material as well as extracted lipids from the Lake Gilmore sediment cores at both a near-shore and mid-lake location. These analyses reveal very low accumulations of organic carbon, concentrated primarily in the gypsum-rich near-shore core. The near-shore sediments show a down-core decrease in abundance of organic carbon as well as depletion in the carbon isotope composition (δ13C) with depth. Bulk carbon did not exhibit the unique, highly depleted, diagnostic signature associated with methanotrophic biomass. Compound-specific isotope analysis (CSIA) of carbon in extracted methanotroph PFLAs can confirm the presence of a methane cycling metabolism at depth. Also, additional extractions have isolated lipids associated with lake-edge grasses. These analyses consider both the chain-length distribution and carbon CSIA of these lipids in order to understand the effect of terrestrial detritus on any preserved methanotroph carbon signal, given the very low amounts of microbial biomass found in lake cores. While the mineralogy does not suggest anaerobic conditions, further investigation includes extraction of archaeal lipids in order to identify the presence of any methanogenic community associated with the putative methanotrophic community.

  10. Impact of Diagenesis on Biosignature Preservation Potential in Playa Lake Evaporites of the Verde Formation, Arizona: Implications for Mars Exploration

    NASA Astrophysics Data System (ADS)

    Shkolyar, S.; Farmer, J. D.

    2016-05-01

    We studied evaporite subfacies in the Verde Fmn., AZ. We identified diagenetic pathways and assessed how diagenesis affected biosignature preservation potential (BPP) in each. Results revealed eight pathways, each with diverse impacts on BPP.

  11. Technical procedures for water resources, Deaf Smith County site, Texas: Volume 1: Environmental Field Program: Final draft

    SciTech Connect

    Not Available

    1987-08-01

    This volume contains Technical Procedures pursuant to the Water Resources Site Study Plan including, determination of basin topographic characteristics, determination of channel and playa lake characteristics, operation of a stream gaging station, operation of a playa lake stage gaging system, and processing of data from a playa lake stage gaging system.

  12. Bolivia

    Atmospheric Science Data Center

    2013-04-18

    article title:  Salt Playas of the Bolivian Altiplano     ... In the high plateau of southwestern Bolivia, two large salt deserts, or playas, are located between the eastern and western Andes. The ... dissolved minerals were left behind to form the playas. The salt pans are now excellent indicators of rainfall fluctuations within the ...

  13. Let the Music Play!--A Short-Term but No Long-Term Detrimental Effect of Vocal Background Music with Familiar Language Lyrics on Foreign Language Vocabulary Learning

    ERIC Educational Resources Information Center

    de Groot, Annette M. B.; Smedinga, Hilde E.

    2014-01-01

    Participants learned foreign vocabulary by means of the paired-associates learning procedure in three conditions: (a) in silence, (b) with vocal music with lyrics in a familiar language playing in the background, or (c) with vocal music with lyrics in an unfamiliar language playing in the background. The vocabulary to learn varied in concreteness…

  14. Surface scattering properties estimated from modeling airborne multiple emission angle reflectance data

    NASA Technical Reports Server (NTRS)

    Guinness, Edward A.; Arvidson, Raymond E.; Irons, J. R.; Harding, D. J.

    1991-01-01

    Here, researchers apply the Hapke function to airborne bidirectional reflectance data collected over three terrestrial surfaces. The objectives of the study were to test the range of natural surfaces that the Hapke model fits and to evaluate model parameters in terms of known surface properties. The data used are multispectral and multiple emission angle data collected during the Geologic Remote Sensing Field Experiment (GRSFE) over a mud-cracked playa, an artificially roughened playa, and a basalt cobble strewn playa at Lunar Lake Playa in Nevada. Airborne remote sensing data and associated field measurements were acquired at the same time. The airborne data were acquired by the Advanced Solid State Array Spectroradiometer (ASAS) instrument, a 29-spectral band imaging system. ASAS reflectance data for a cobble-strewn surface and an artificially rough playa surface on Lunar Lake Playa can be explained with the Hanke model. The cobble and rough playa sites are distinguishable by a single scattering albedo, which is controlled by material composition; by the roughness parameter, which appears to be controlled by the surface texture and particle size; and the symmetry factor of the single particle phase function, which is controlled by particle size and shape. A smooth playa surface consisting of compacted, fine-grained particles has reflectance variations that are also distinct from either the cobble site or rough playa site. The smooth playa appears to behave more like a Lambertian surface that cannot be modeled with the Hapke function.

  15. Numerical dating of a Late Quaternary spit-shoreline complex at the northern end of Silver Lake playa, Mojave Desert, California: A comparison of the applicability of radiocarbon, luminescence, terrestrial cosmogenic nuclide, electron spin resonance, U-series and amino acid racemization methods

    USGS Publications Warehouse

    Owen, L.A.; Bright, Jordon; Finkel, R.C.; Jaiswal, M.K.; Kaufman, D.S.; Mahan, S.; Radtke, U.; Schneider, J.S.; Sharp, W.; Singhvi, A.K.; Warren, C.N.

    2007-01-01

    A Late Quaternary spit-shoreline complex on the northern shore of Pleistocene Lake Mojave of southeastern California, USA was studied with the goal of comparing accelerator mass spectrometry (AMS) radiocarbon, luminescence, electron spin resonance (ESR), terrestrial cosmogenic radionuclide (TCN) surface exposure, amino acid racemization (AAR) and U-series dating methods. The pattern of ages obtained by the different methods illustrates the complexity of processes acting in the lakeshore environment and highlights the utility of a multi-method approach. TCN surface exposure ages (mostly ???20-30 ka) record the initial erosion of shoreline benches, whereas radiocarbon ages on shells (determined in this and previous studies) within the spit, supported by AAR data, record its construction at fluctuating lake levels from ???16 to 10 ka. Luminescence ages on spit sediment (???6-7 ka) and ESR ages on spit shells (???4 ka) are anomalously young relative to radiocarbon ages of shells within the same deposits. The significance of the surprisingly young luminescence ages is not clear. The younger ESR ages could be a consequence of post-mortem enrichment of U in the shells. High concentrations of detrital thorium in tufa coating spit gravels inhibited the use of single-sample U-series dating. Detailed comparisons such as this provide one of the few means of assessing the accuracy of Quaternary dating techniques. More such comparisons are needed. ?? 2007 Elsevier Ltd and INQUA.

  16. The Origin of the Meridiani Sediments: the Key for Understanding the Formation of Sulfates and Layered Deposits on Mars

    NASA Technical Reports Server (NTRS)

    Niles, P.B.; Michalski, J.

    2009-01-01

    Following the discoveries made by the Opportunity rover at Meridiani Planum, members of the MER science team proposed that the Meridiani deposits are playa evaporites reworked by eolian processes. Alternate hypotheses have also been proposed to explain the deposits at Meridiani Planum, and these have highlighted serious problems with the provenance of the sedimentary material in the proposed playa hypothesis. These problems include: indications of cation-conservative weathering, the lack of a topographic basin, the intimate commingling of the most soluble and least soluble salts, and the overall scale of the deposit. These observations are important challenges to the playa scenario, and suggest that the sediment was derived from a different source.

  17. 40 CFR 117.1 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., all terms shall have the meanings stated in 40 CFR part 116. (a) Reportable quantities means.... Wetlands generally included playa lakes, swamps, marshes, bogs, and similar areas such as sloughs,...

  18. 40 CFR 117.1 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., all terms shall have the meanings stated in 40 CFR part 116. (a) Reportable quantities means.... Wetlands generally included playa lakes, swamps, marshes, bogs, and similar areas such as sloughs,...

  19. 40 CFR 117.1 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., all terms shall have the meanings stated in 40 CFR part 116. (a) Reportable quantities means.... Wetlands generally included playa lakes, swamps, marshes, bogs, and similar areas such as sloughs,...

  20. Neurotoxicity of Thyroid Disrupting Contaminants

    EPA Science Inventory

    Thyroid hormones playa critical role in the normal development ofthe mammalian brain. Thyroid disrupting chemicals (TDCs) are environmental contaminants that alter the structure or function ofthe thyroid gland, alter regulatory enzymes associated with thyroid hormone (TH) homeost...

  1. Water resources

    NASA Technical Reports Server (NTRS)

    Simons, D. B.

    1975-01-01

    Applications of remote sensing technology to analysis of watersheds, snow cover, snowmelt, water runoff, soil moisture, land use, playa lakes, flooding, and water quality are summarized. Recommendations are given for further utilization of this technology.

  2. Threshold velocities for input of soil particles into the air by desert soils

    SciTech Connect

    Gillette, D.A.; Adams, J.; Endo, A.; Smith, D.; Kihl, R.

    1980-10-20

    Desert soils mostly from the Mojave Desert were tested for threshold friction velocity (the friction velocity above which soil erosion takes place) with an open-bottomed portable wind tunnel. Several geomorphological settings were chosen to be representative of much of the surface of the Mojave Desert, for example, playas, alluvial fans, and aeolian features. Variables which increase threshold velocity are decreasing proportion of sand, increasing size of dry aggregates of the soil, and increasing fraction of the soil mass larger than 1 mm. Threshold velocity increases with different types of soil surfaces in the following order: disturbed soils (except disturbed heavy clay soils), sand dunes, alluvial and aeolian sand deposits, disturbed playa soils, skirts of playas, playa centers, and desert pavement (alluvial deposits). 21 references, 5 figures, 6 tables.

  3. Neogene and Quaternary foraminifera and paleoenvironments of a corehole from Horn Island, Mississippi

    USGS Publications Warehouse

    Gibson, Thomas G.

    1994-01-01

    The only semipermanent surface water available on the Southern High Plains plateau of Texas and New Mexico is contained in saline lakes and in the playa lakes that form in shallow depressions, called playa basins, following heavy rainfall. The playas generally are accepted as the main source of recharge to the underlying High Plains (Ogallala) aquifer of the region, and they constitute the major wildlife habitat on the Southern High Plains. Their use as water sources, holding ponds, and waste-disposal sites by agricultural and industrial operations may potentially lead to ground-water contamination and habitat degradation. Therefore, playa lakes will play an essential role in the collection of surface-water quality and ecological data for the Southern High Plains study unit of the National Water-Quality Assessment program of the U.S. Geological Survey.

  4. Remote sensing of dust source heterogeneity; Case study Etosha Pan, Namibia

    NASA Astrophysics Data System (ADS)

    Bryant, Robert; Eckardt, Frank; Vickery, Kate; Wiggs, Giles; Hipondoka, Martin; Murray, Jon; Baddock, Matt; Brindley, Helen; King, James; Nield, Jo; Thomas, Dave; Washington, Richard; Haustein, Karsten

    2016-04-01

    Etosha Pan is a large playa situated in semi-arid northern Namibia. It sits in a basin 1000 m amsl, has a surface area of approximately 5000 km2. This playa has been identified as one of the largest sources of mineral dust in the Southern Hemisphere. To both map dust emission events and uncover sub-basin scale controls on mineral dust emissions, multiple time-series of remote sensing data (2004-2014) for this playa are presented. These depict: (a) mineral aerosol concentration in the vicinity of the playa, and (b) the surface hydrology of the playa basin. Seasonal wind velocities/direction data are also presented (ERA-Interim), and together with aerosol characterization, they depict clear seasonality in dust emission/transport, significant inter-annual variability in aerosol loadings, and evidence of inter-event variability in plume chemistry. The gross spatial and temporal behavior of the dust cycle of this ephemeral lake can be directly related to inherent variability in groundwater depth and periods of surface inundation. In most years, surface water interacts with < 30% of the playa surface; often for relatively short periods (< 3 months). However, Etosha Pan can also experience extensive periods of flooding and inundation (>80% basin cover, lasting for up to 12 months). Data from these wet and dry periods, in conjunction with locations of observed dust plumes emanating from the playa surface, allow us to identify direct links between dust emission and surface hydrology; thereby allowing, for the first time, a characterization of the emission potential of the playa surface. These observations have provided a clear context for both field investigation and modelling of this dust source as part of the DO4-Models (Dust Observations for Models) project that aimed to understand the variability in dust emission processes at relevant scales for climate modelling.

  5. Nitrate reduction during ground-water recharge, Southern High Plains, Texas

    NASA Astrophysics Data System (ADS)

    Fryar, Alan E.; Macko, Stephen A.; Mullican, William F., III; Romanak, Katherine D.; Bennett, Philip C.

    2000-01-01

    In arid and semi-arid environments, artificial recharge or reuse of wastewater may be desirable for water conservation, but NO 3- contamination of underlying aquifers can result. On the semi-arid Southern High Plains (USA), industrial wastewater, sewage, and feedlot runoff have been retained in dozens of playas, depressions that focus recharge to the regionally important High Plains (Ogallala) aquifer. Analyses of ground water, playa-basin core extracts, and soil gas in an 860-km 2 area of Texas suggest that reduction during recharge limits NO 3- loading to ground water. Tritium and Cl - concentrations in ground water corroborate prior findings of focused recharge through playas and ditches. Typical δ15N values in ground water (>12.5‰) and correlations between δ15N and ln CNO -3-N suggest denitrification, but O 2 concentrations ≥3.24 mg l -1 indicate that NO 3- reduction in ground water is unlikely. The presence of denitrifying and NO 3--respiring bacteria in cores, typical soil-gas δ15N values <0‰, and decreases in NO 3--N/Cl - and SO 42-/Cl - ratios with depth in cores suggest that reduction occurs in the upper vadose zone beneath playas. Reduction may occur beneath flooded playas or within anaerobic microsites beneath dry playas. However, NO 3--N concentrations in ground water can still exceed drinking-water standards, as observed in the vicinity of one playa that received wastewater. Therefore, continued ground-water monitoring in the vicinity of other such basins is warranted.

  6. Hyperspectral Mapping of Iron-bearing Minerals Associated with Dry and Ephemeral Lakes

    NASA Astrophysics Data System (ADS)

    Farrand, W. H.; Bowen, B. B.

    2014-12-01

    This research project is utilizing data from the Hyperspectral Imager for the Coastal Ocean (HICO) on the International Space Station (ISS) to examine a set of playas and ephemeral lakes in Australia and in the southwestern United States. HICO collects hyperspectral data from 0.35 to 1.08 μm thus excluding the SWIR vibrational overtone region of clays and carbonates. We are assessing the utility of HICO for detecting iron-bearing minerals and materials associated with playas and mapping their fractional abundance outside of the playa boundaries. Sites being investigated include the clastics-dominated Railroad Valley and Lunar Lake playas of Nevada, the evaporite-dominated Bonneville Salt Flats, and the acid-saline Lake Tyrrell of northwest Victoria, Australia. HICO, and supporting airborne hyperspectral datasets (AVIRIS and HyMap), are being converted from at-sensor radiance to surface reflectance using the FLAASH radiance transfer-based atmospheric correction software. Fe-bearing minerals and materials are determined through a standardized endmember detection approach using the commercial ENVI software and mapped using a variety of approaches including linear spectral mixture analysis, constrained energy minimization, and spectral feature fitting. Interpretations of remote data are guided by field-based observations and mapping. We are using the remote sensing data to assess the surface state of the playa (wet vs. dry, soft vs. hard). These factors have bearing in that dusts stripped from playa surfaces can affect nearby human communities and agricultural fields. Playas are also used for recreation and sometimes as transportation corridors and their physical state has important bearing for those functions. Assessing the types of minerals present has relevance for their impact as wind-entrained particulates that could have adverse effects on the health of humans, crops, or livestock.

  7. Recharge from a subsidence crater at the Nevada test site

    USGS Publications Warehouse

    Wilson, G. V.; Ely, D.M.; Hokett, S. L.; Gillespie, D. R.

    2000-01-01

    Current recharge through the alluvial fans of the Nevada Test Site (NTS) is considered to be negligible, but the impact of more than 400 nuclear subsidence craters on recharge is uncertain. Many of the craters contain a playa region, but the impact of these playas has not been addressed. It was hypothesized that a crater playa would focus infiltration through the surrounding coarser-grained material, thereby increasing recharge. Crater U5a was selected because it represented a worst case for runoff into craters. A borehole was instrumented for neutron logging beneath the playa center and immediately outside the crater. Physical and hydraulic properties were measured along a transect in the crater and outside the crater. Particle-size analysis of the 14.6 m of sediment in the crater and morphological features of the crater suggest that a large ponding event of ≈63000 m3 had occurred since crater formation. Water flow simulations with HYDRUS-2D, which were corroborated by the measured water contents, suggest that the wetting front advanced initially by as much as 30 m yr−1 with a recharge rate 32 yr after the event of 2.5 m yr−1Simulations based on the measured properties of the sediments suggest that infiltration will occur preferentially around the playa perimeter. However, these sediments were shown to effectively restrict future recharge by storing water until removal by evapotranspiration (ET). This work demonstrated that subsidence craters may be self-healing.

  8. Depositional model for carbonate-evaporite cyclicity: Middle Pennsylvanian of Paradox basin

    SciTech Connect

    Kendall, A.C.

    1987-05-01

    The Paradox basin is a classic area for the study of relations between carbonates and evaporites. Previous depositional models assume carbonates and evaporites are coeval, implying that the evaporites were deep water deposits. Stratigraphic relationships are, however, complicated by previously unrecognized salt dissolution. Restoration of the missing salts indicates that evaporites entirely postdate marine carbonates in each cycle. Anhydrites and silty dolomites that succeed halites are reinterpreted as shallow hypersaline to subaerial deposits. These playa-like sediments are abruptly overlain by organic-rich shales that represent anoxic and the deepest-water deposits in the sequence. Paradox basin salts and succeeding playa deposits formed in a deep but desiccated basin. Sea level rises drowned the formerly exposed basin rims, causing sudden complete floodings of the basin and the abrupt contacts between playa deposits and deep-water shales. The shale-carbonate-evaporite sequences that form lower parts of cycles resulted from sea level falls. These ultimately exposed basin rims, isolating the basin, and allowed evaporative draw down and the deposition of basin-central evaporites. In contrast, the halite-anhydrite-silty dolomite sequences of the upper parts of cycles arose when sediment aggradation caused expansion of the evaporite depositional area onto basin flanks. There brine reflux became more significant. This reduced residence times of brines in the basin so that, progressively, salinities decreased and only less-saline sediments were able to persist in the playa environment. Cycles end (or begin) when renewed sea level rises drowned the basin-central playas.

  9. Ground truthing for methane hotspots at Railroad Valley, NV - application to Mars

    NASA Astrophysics Data System (ADS)

    Detweiler, A. M.; Kelley, C. A.; Bebout, B.; McKay, C. P.; DeMarines, J.; Yates, E. L.; Iraci, L. T.

    2011-12-01

    During the 2010 Greenhouse gas Observing SATellite (GOSAT) calibration and validation campaign at Railroad Valley (RRV) playa, NV, unexpected methane and carbon dioxide fluctuations were observed at the dry lakebed. Possible sources included the presence of natural gas (thermogenic methane) from oil deposits in the surrounding playa, and/or methane production from microbial activity (biogenic) in the subsurface of the playa. In the summer of 2011, measurements were undertaken to identify potential methane sources at RRV. The biogenicity of the methane was determined based on δ13C values and methane/ethane ratios. Soil gas samples and sediments were collected at different sites in the playa and surrounding areas. The soils of the playa consist of a surface crust layer (upper ~ 10 cm) grading to a dense clay below about 25 cm. Soil gas from the playa, sampled at about 20 and 80 cm depths, reflected atmospheric methane concentrations, ranging from 2 to 2.4 ppm, suggesting that no methane was produced within the playa. Natural springs on the northeast and western border of the playa, detected as methane hotspots from a flyover by the Sensor Integrated Environmental Remote Research Aircraft (SIERRA), were also sampled. Bubbles in these springs had methane concentrations that ranged from 69 to 84% by volume. In addition, ethane was detected at very low concentrations, giving methane/ethane ratios in excess of 100,000, indicating biogenic methane in the springs. Soils and sediments collected at the playa and spring sites were incubated in vials over a period of ~23 days. Methane production was observed in the spring sites (avg. 228.6 ± 49.1 nmol/g/d at Kate Springs), but was not evident for the playa sites. The incubation data, therefore, corroborated in situ methane concentration measurements. Particulate organic carbon (POC) was low for all sites samples (0.05-0.38%), with the exception of Kate Springs, which had a much higher POC concentration of 3.4 ± 0

  10. In situ spectroradiometric quantification of ERTS data

    NASA Technical Reports Server (NTRS)

    Yost, E. (Principal Investigator)

    1972-01-01

    The author has identified the following significant results. Additive color photographic analysis of ERTS-1 multispectral imagery indicates that the presence of soil moisture in playas (desert dry lakes) can be readily detected from space. Time sequence additive color presentations in which 600-700 nm bands taken at three successive 18-day cycles show that changes in soil moisture of playas with time can be detected as unique color signatures and can probably be quantitatively measured using photographic images of multispectral scanner data.

  11. 13. View of disassembled steam engine showing cylinder, piston rod, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. View of disassembled steam engine showing cylinder, piston rod, parallel motion links and steam chest. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  12. 8. General oblique view: east side of south end, from ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. General oblique view: east side of south end, from the Dos Hermanos Highway Bridge - Puente Guillermo Esteves, Spanning San Antonio Channel at PR-25 (Juan Ponce de Leon Avenue), San Juan, San Juan Municipio, PR

  13. 1. Oblique view: east side, from Condado Lagoon Beach on ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Oblique view: east side, from Condado Lagoon Beach on southeast (context) - Puente Guillermo Esteves, Spanning San Antonio Channel at PR-25 (Juan Ponce de Leon Avenue), San Juan, San Juan Municipio, PR

  14. 10. OBLIQUE VIEW OF THE BRIDGE FROM THE SOUTHEAST. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. OBLIQUE VIEW OF THE BRIDGE FROM THE SOUTHEAST. - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  15. 9. Partial elevation of west side showing pillar, central and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. Partial elevation of west side showing pillar, central and southern sections, from San Antonio Highway Bridge. - Puente Ferroviario San Antonio, Spanning San Antonio Channel at PR-1, San Juan, San Juan Municipio, PR

  16. 3. SOUTHEAST APPROACHELEVATION. Puente de la Marina, San LorenzoFlorida ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. SOUTHEAST APPROACH-ELEVATION. - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  17. 3. General view of bridge and channel, from southwest, with ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. General view of bridge and channel, from southwest, with fishermen's facilities in the background. - Puente Ferroviario San Antonio, Spanning San Antonio Channel at PR-1, San Juan, San Juan Municipio, PR

  18. 3. Partial elevation: west side of north end, from the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Partial elevation: west side of north end, from the San Antonio Railroad Bridge - Puente Guillermo Esteves, Spanning San Antonio Channel at PR-25 (Juan Ponce de Leon Avenue), San Juan, San Juan Municipio, PR

  19. 4. Partial elevation: west side of south end, from the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. Partial elevation: west side of south end, from the San Antonio Railroad Bridge - Puente Guillermo Esteves, Spanning San Antonio Channel at PR-25 (Juan Ponce de Leon Avenue), San Juan, San Juan Municipio, PR

  20. 9. OBLIQUE VIEW OF THE BRIDGE FROM THE SOUTH. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. OBLIQUE VIEW OF THE BRIDGE FROM THE SOUTH. - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  1. 7. Detail view: east side of north end, showing remains ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Detail view: east side of north end, showing remains of Fort San Antonio - Puente Guillermo Esteves, Spanning San Antonio Channel at PR-25 (Juan Ponce de Leon Avenue), San Juan, San Juan Municipio, PR

  2. 14. Oblique detail; understructure beneath short span used for docking ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Oblique detail; understructure beneath short span used for docking fishing boats, north of northen pillar, from northwest. - Puente Ferroviario San Antonio, Spanning San Antonio Channel at PR-1, San Juan, San Juan Municipio, PR

  3. 4. NORTHWEST APPROACHELEVATION. Puente de la Marina, San LorenzoFlorida ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. NORTHWEST APPROACH-ELEVATION. - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  4. 5. NORTHEAST SIDEELEVATION. Puente de la Marina, San LorenzoFlorida ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. NORTHEAST SIDE-ELEVATION. - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  5. 8. Detail view of steam dome attached to top of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. Detail view of steam dome attached to top of Lancashire double flue boiler. - Hacienda Azucarera El Coto, Sugar Mill Ruins, .5 Mi. SW of Rt. 347 Bridge Over Guanajibo River, San German, San German Municipio, PR

  6. 5. Detail view of masonry foundations and flue openings for ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. Detail view of masonry foundations and flue openings for Jamaican Train. - Hacienda Azucarera El Coto, Sugar Mill Ruins, .5 Mi. SW of Rt. 347 Bridge Over Guanajibo River, San German, San German Municipio, PR

  7. 7. Photocopy of measured drawing, ca. 1881; details of castiron ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Photocopy of measured drawing, ca. 1881; details of cast-iron tower, stairway, cast-iron lantern and balcony balustrade - Faro de los Morillos de Cabo Rojo, Los Morillos de Cabo Rojo, Cabo Rojo, Cabo Rojo Municipio, PR

  8. 7. Detail view of steam engine showing cylinder, crosshead guide, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Detail view of steam engine showing cylinder, crosshead guide, eccentric red and valve mechanism. - Hacienda Azucarera la Igualdad, Sugar Mill Ruins & Steam Engine, PR Route 332, Guanica, Guanica Municipio, PR

  9. 4. View of steam engine looking SW showing valve end; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. View of steam engine looking SW showing valve end; flywheel and reduction gears to left. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  10. 2. 3/4 view looking SW showing threeroll can mill, reduction ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. 3/4 view looking SW showing three-roll can mill, reduction gear, flywheel with steam engine in background. - Hacienda Azucarera la Igualdad, Sugar Mill Ruins & Steam Engine, PR Route 332, Guanica, Guanica Municipio, PR

  11. 6. Detail view of steam engine showing base, governor drive ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Detail view of steam engine showing base, governor drive pulley and eccentric. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  12. 12. View of disassembled steam engine sitting in open shed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. View of disassembled steam engine sitting in open shed showing base, columns and entablature. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  13. 7. Detail view of steam engine showing flywheel spokes and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Detail view of steam engine showing flywheel spokes and hub sector. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  14. 10. Side view of cane mill looking NW with steam ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Side view of cane mill looking NW with steam engine in background. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  15. 46. View of Plaza de Armas taken through archway between ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    46. View of Plaza de Armas taken through archway between Plaza de Armas and Carmen Bastion, looking southwest - Castillo de San Felipe del Morro, Northwest end of San Juan, San Juan, San Juan Municipio, PR

  16. 17. Detail view of coupling shaft connection between reduction gear ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. Detail view of coupling shaft connection between reduction gear and cane mill drive gears - Hacienda Azucarera la Igualdad, Sugar Mill Ruins & Steam Engine, PR Route 332, Guanica, Guanica Municipio, PR

  17. 17. View of disassembled reduction gear parts including bull and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. View of disassembled reduction gear parts including bull and intermediate gears and pedestal bearing. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  18. 1. General view of guard house and entrance to Coast ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. General view of guard house and entrance to Coast Guard Base from La Putilla Street, looking southwest - U.S. Coast Guard Base, San Juan, Guard House, La Puntilla Finalle, San Juan, San Juan Municipio, PR

  19. 25. Front elevation of coffee husker showing framework supporting gears, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. Front elevation of coffee husker showing framework supporting gears, shaft and pulleys that drove husker. HAER PR, 6-MAGU, 1B-10 - Hacienda Buena Vista, PR Route 10 (Ponce to Arecibo), Magueyes, Ponce Municipio, PR

  20. 12. Detail: pier wall and undersides of encased steel beams: ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. Detail: pier wall and undersides of encased steel beams: easternmost steel beam span, facing west. - Puente del Caño Perdomo, Route PR-2 spanning Cano Perdomo Channel, Arecibo, Arecibo Municipio, PR

  1. 50. Trash strainer and sluice gate at top of castiron ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    50. Trash strainer and sluice gate at top of cast-iron pipe penstock leading to Barker turbine. HAER PR, 6-MAGU, 1D-2 - Hacienda Buena Vista, PR Route 10 (Ponce to Arecibo), Magueyes, Ponce Municipio, PR

  2. 32. Coffee bean sluiceway on ground floor showing chute bringing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. Coffee bean sluiceway on ground floor showing chute bringing beans from first floor hopper. HAER PR, 6-MAGU, 1B-17 - Hacienda Buena Vista, PR Route 10 (Ponce to Arecibo), Magueyes, Ponce Municipio, PR

  3. View of furnace feeding into the drum type coffee dryer ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of furnace feeding into the drum type coffee dryer on second floor of structure, view towards southeast - Santaella Coffee Processing Site, Highway 139, Kilometer 10.6, Maraguez, Ponce Municipio, PR

  4. 18. DETAIL VIEW OF DEVICE ON OUTSIDE OF COFFEE HUSKER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. DETAIL VIEW OF DEVICE ON OUTSIDE OF COFFEE HUSKER THAT ADJUSTED ANGLE OF HUSKER VAT WALLS - Hacienda Cafetalera Santa Clara, Coffee Mill, KM 19, PR Route 372, Hacienda La Juanita, Yauco Municipio, PR

  5. View towards west from across Rio Cerrillos of coffee processing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View towards west from across Rio Cerrillos of coffee processing structure (on left) with the Santaella residence (on right) - Santaella Coffee Processing Site, Highway 139, Kilometer 10.6, Maraguez, Ponce Municipio, PR

  6. Planar view of northwest side of coffee processing structure No. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Planar view of northwest side of coffee processing structure No. 1, view towards the southeast - Finca Silem, Coffee Processing Structure No. 1, Highway 139, Kilometer 9.3, Maraguez, Ponce Municipio, PR

  7. Interior view of coffee processing structure No. 1, showing concrete ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view of coffee processing structure No. 1, showing concrete reservoirs on floor, view towards the west - Finca Silem, Coffee Processing Structure No. 1, Highway 139, Kilometer 9.3, Maraguez, Ponce Municipio, PR

  8. 17. DETAIL VIEW OF WHAT APPEARS TO BE STIRRING FORK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. DETAIL VIEW OF WHAT APPEARS TO BE STIRRING FORK THAT MIXED COFFEE BEANS AS THEY WERE HUSKED - Hacienda Cafetalera Santa Clara, Coffee Mill, KM 19, PR Route 372, Hacienda La Juanita, Yauco Municipio, PR

  9. Planar view towards the southeast of the front of coffee ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Planar view towards the southeast of the front of coffee processing structure with the Santaella residence to the left - Santaella Coffee Processing Site, Highway 139, Kilometer 10.6, Maraguez, Ponce Municipio, PR

  10. Exterior view of hipped roof with coffee processing structure in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior view of hipped roof with coffee processing structure in background, view towards the southwest - Pou Coffee Processing Structure, Casa No. 2, Highway 139, Kilometer 12, Maraguez, Ponce Municipio, PR

  11. View towards east of interior wall structure with parts of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View towards east of interior wall structure with parts of coffee despulpadora in foreground - Finca Silem, Coffee Processing Structure No. 1, Highway 139, Kilometer 9.3, Maraguez, Ponce Municipio, PR

  12. View towards the northeast of coffee beans drying on the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View towards the northeast of coffee beans drying on the third floor with hopper and drum type dryer in background - Santaella Coffee Processing Site, Highway 139, Kilometer 10.6, Maraguez, Ponce Municipio, PR

  13. 13. DETAIL OF BEVEL GEAR TRANSFERRING HORIZONTAL DRIVE FROM MAIN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. DETAIL OF BEVEL GEAR TRANSFERRING HORIZONTAL DRIVE FROM MAIN WATERWHEEL SHAFT TO VERTICAL SHAFT DRIVING COFFEE HUSKING MILL ON SECOND FLOOR - Hacienda Cafetalera Santa Clara, Coffee Mill, KM 19, PR Route 372, Hacienda La Juanita, Yauco Municipio, PR

  14. Nrf2 Expression Modifies Influenza A Entry and Replication inNasal Epithelial Cells

    EPA Science Inventory

    Influenza infection is a major cause of morbidity and mortality worldwide, especially during pandemics outbreaks. Emerging data indicate that phase II antioxidant enzyme pathways could playa role in virus-associated inflammation and immune clearance. While Nrf2-dependent gene exp...

  15. Play as Experience

    ERIC Educational Resources Information Center

    Henricks, Thomas S.

    2015-01-01

    The author investigates what he believes one of the more important aspects of play--the experience it generates in its participants. He considers the quality of this experience in relation to five ways of viewing play--as action, interaction, activity, disposition, and within a context. He treats broadly the different forms of affect, including…

  16. Monitoring sediment transfer processes on the desert margin

    NASA Technical Reports Server (NTRS)

    Millington, Andrew C.; Arwyn, R. Jones; Quarmby, Neil; Townshend, John R. G.

    1987-01-01

    LANDSAT Thematic Mapper and Multispectral Scanner data have been used to construct change detection images for three playas in south-central Tunisia. Change detection images have been used to analyze changes in surface reflectance and absorption between wet and dry season (intra-annual change) and between different years (inter-annual change). Change detection imagery has been used to examine geomorphological changes on the playas. Changes in geomorphological phenomena are interpreted from changes in soil and foliar moisture levels, differences in reflectances between different salt and sediments and the spatial expression of geomorphological features. Intra-annual change phenomena that can be detected from multidate imagery are changes in surface moisture, texture and chemical composition, vegetation cover and the extent of aeolian activity. Inter-annual change phenomena are divisible into those restricted to marginal playa facies (sedimentation from sheetwash and alluvial fans, erosion from surface runoff and cliff retreat) and these are found in central playa facies which are related to the internal redistribution of water, salt and sediment.

  17. The Education of the Active Televiewer of School Age.

    ERIC Educational Resources Information Center

    Munoz, Patricio Calderon; Torres, Miguel Reyes

    In response to a series of problem symptoms related to the influence of television on students, a team of professors at the Universidad de Playa Ancha de Ciencias de la Educacion in Chile undertook a project designed to train television viewers to become critical viewers of the medium. Specific objectives of the project included: (1) to design a…

  18. Groundwater discharge by evapotranspiration, Dixie Valley, west-central Nevada, March 2009-September 2011

    USGS Publications Warehouse

    Garcia, C. Amanda; Huntington, Jena M; Buto, Susan G.; Moreo, Michael T.; Smith, J. LaRue; Andraski, Brian J.

    2014-01-01

    Mean annual basin-scale ETg totaled about 28 million cubic meters (Mm3) (23,000 acre-feet [acre-ft]), and represents the sum of ETg from all ET units. Annual groundwater ET from vegetated areas totaled about 26 Mm3 (21,000 acre-ft), and was dominated by the moderate-to-dense shrubland ET unit (54 percent), followed by sparse shrubland (37 percent) and grassland (9 percent) ET units. Senesced grasses observed in the northern most areas of the moderate-to-dense ET unit likely confounded the vegetation index and led to an overestimate of ETg for this ET unit. Therefore, mean annual ETg for moderate-to-dense shrubland presented here is likely an upper bound. Annual groundwater ET from the playa ET unit was 2.2 Mm3 (1,800 acre-ft), whereas groundwater ET from the playa lake ET unit was 0–0.1 Mm3 (0–100 acre-ft). Oxygen-18 and deuterium data indicate discharge from the playa center predominantly represents removal of local precipitation-derived recharge. The playa lake estimate, therefore, is considered an upper bound. Mean annual ETg estimates for Dixie Valley are assumed to represent the pre‑development, long-term ETg rates within the study area.

  19. 75 FR 23608 - Final Flood Elevation Determinations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-04

    ... and Review, 58 FR 51735. Executive Order 13132, Federalism. This final rule involves no policies that... 1978, 3 CFR, 1978 Comp., p. 329; E.O. 12127, 44 FR 19367, 3 CFR, 1979 Comp., p. 376. Sec. 67.11 0 2... the intersection of Southeast 3rd Avenue and South Whitaker Road. Playa Lake 23 Approximately...

  20. Nasal lavage natural killer cell function is suppressed in smokers after live attenuated influenza virus

    EPA Science Inventory

    Background Modified function of immune cells in nasal secretions may playa role in the enhanced susceptibility to resp iratory viruses that is seen in smokers. Innate immune cells in nasal secretions have largely been characterized by cellular differentials using morphologic c...

  1. Habitat preferences of migrant and wintering northern harriers in northwestern Texas

    USGS Publications Warehouse

    Littlefield, C.D.; Johnson, D.H.

    2005-01-01

    We studied habitat preferences of northern harriers ( Circus cyaneus) in four counties of the Southern High Plains of northwestern Texas from October 1989 to May 1995. Harriers generally arrived in late July and departed in April. They hunted over a variety of habitats in the study area but mainly in Conservation Reserve Program (CRP) grasslands and vegetated playa basins. CRP grasslands, playa basins, and shortgrass prairie were used disproportionately to their availability, whereas winter wheat was used less than its availability. Brown harriers (adult females or subadults of either sex) foraged in CRP about as often as adult males but more frequently in playas and prairies, whereas adult males foraged more in winter wheat. As underground water sources for irrigation continue to be depleted, agricultural practices are likely to change. Depending on how the land is used after irrigation ceases, harriers may benefit if CRP grasslands, vegetated playas, and shortgrass prairies persist. If dominant land use reverts to livestock grazing, however, the harrier population will be negatively affected.

  2. Education as Free Use: Giorgio Agamben on Studious Play, Toys, and the Inoperative Schoolhouse

    ERIC Educational Resources Information Center

    Lewis, Tyson E.

    2014-01-01

    In this essay, I argue that the work of Giorgio Agamben provides us with a theory of studious play which cuts across many of the categories that polarize educational thought. Rather than either ritualized testing or constructivist playfulness, Agamben provides a model of what he refers to as studious play--a practice which suspends the logic of…

  3. The Landscape Documentary: Unveiling the Face of "Wasteland."

    ERIC Educational Resources Information Center

    Denton, Craig L.

    This paper outlines the process of a photographic landscape documentary project which set out to unveil the face of Utah's West Desert (a 42,000 square-mile, sparsely-populated, broad, rugged land of salt bed "playas" and high mountain ranges) comprising one-third of the state and which hoped to make the West Desert, recently under consideration…

  4. Children's Free Play: What Has Happened to It?

    ERIC Educational Resources Information Center

    Partridge, Susan

    This paper addresses the current abandonment of children's free play--a proven, broad-based, indispensable learning experience--in favor of formal learning and instruction. Educational research has found that play is the natural learning medium of children, yet this understanding is not guiding educators' practice. This condition has caused many…

  5. Graphic-Narrative Play: Young Children's Authoring through Drawing and Telling

    ERIC Educational Resources Information Center

    Wright, Susan

    2007-01-01

    This arts-based research illustrates how young children engage in "graphic-narrative play"--a personal fantasy-based experience depicted on paper--while representing imaginary worlds centered on the topic, "what the future will be like". The descriptions show how the children not only made representations, but also manipulated these in abstract…

  6. Play Theory: A Personal Journey and New Thoughts

    ERIC Educational Resources Information Center

    Sutton-Smith, Brian

    2008-01-01

    A preeminent play-theory scholar reviews a lifetime devoted to the study of play in a lively, even playful, recounting of his illustrious career and some of its autobiographical roots. The author covers the development of his three major theories of play--as a viability variable, as culturally relative play forms, and as a co-evolutionary…

  7. 75 FR 52972 - Notice of Temporary Closures and Restrictions on Specific Uses of Public Lands in Pershing County...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-30

    ... safety and resources on public lands within and adjacent to the Burning Man Festival on the Black Rock... lands on and adjacent to the Burning Man Event conducted on the Black Rock Desert playa within the Black... necessary to provide a safe environment for the participants of the Burning Man Festival and to members...

  8. 77 FR 48529 - Notice of Temporary Closure and Temporary Restrictions of Specific Uses on Public Lands in...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-14

    ... to protect public safety and resources on public lands within and adjacent to the Burning Man event... Burning Man event permitted on the Black Rock Desert playa within the Black Rock Desert-High Rock Canyon... environment for the participants of the Burning Man event and to members of the public visiting the Black...

  9. 78 FR 36748 - Caribbean Fishery Management Council; Scoping Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-19

    ... p.m.--Asociaci n de Pescadores Unidos de Playa Hucares de Naguabo, Naguago, Puerto Rico. ] July 12... agencies representatives on the development of island-specific fishery management plans for Puerto Rico, St... will be held in Puerto Rico and in the U.S. Virgin Islands. See SUPPLEMENTARY INFORMATION for...

  10. Development of Saline Flow Systems in Closed Basins

    NASA Astrophysics Data System (ADS)

    Huntington, J. M.; Halford, K. J.; Garcia, C.

    2011-12-01

    Saline playas frequently occur in closed basins, such as the Humboldt Salt Marsh in Dixie Valley, in west-central Nevada. This playa is the terminus of a local groundwater flow system, is comprised of dense clay, and has shallow groundwater salinities more than 5 times the salinity of sea water (TDS concentrations of 172,000 to 311,900 mg/L). The saline system has developed and continues to expand as surface runoff and groundwater evaporates from the playa surface and dissolved solutes remain. Negligible discharge of fresh groundwater occurs where the saline system is present, because the fresh-water / saltwater interface that abuts the playa is analogous hydraulically to interfaces in coastal aquifers. The period of time necessary to develop a relatively isolated saline flow system was quantified by simulating a hypothetical cross-section with a variable-density groundwater flow and transport model (SEAWAT). Preliminary analysis suggests that the perimeter of saline system expands between 10 and 100 m every 10,000 years.

  11. [Community structure of sponges (Porifera) in three reefs at Morrocoy National Park, Venezuela and its correspondence with some environmental variables].

    PubMed

    Romero, Marco A; Villamizar, Estrella; Malaver, Nora

    2013-09-01

    Sponges have an important ecological role in coral reef ecosystems. However, when compared to other benthic Phyla, it has been little researched. This research was focused in the variability of the community structure of sponges in three locations at Morrocoy National Park (Cayo Sombrero, Playa Mero and Punta Brava) exposed to different environmental conditions (transparency and currents intensity) and affected in different degree of severity by a mass mortality event in 1996. A total of 15 transects (10 m long and 1 m wide) were evaluated in three strata (between 3 and 15 m depth) in each site, where all the individuals were counted by species. Relative abundance by species, diversity and evenness were calculated. Locations showed differences respect turbidity, wave and current intensity. 27 species were found in Morrocoy; Cayo Sombrero (23), Playa Mero (18) and Punta Brava (15). Agelas sceptrum, Amphimedon erina and Niphates erecta were the most common in first location; Niphates erecta and Dysidea etheria in Playa Mero and Dysidea etheria, Niphates erecta and Amphimedon erina in Punta Brava. The species composition showed statistical differences between all three locations; Cayo Sombrero resulted the most diverse and even, followed by Playa Mero and Punta Brava. According to Sorensen Similarity Index results, Cayo Sombrero and Playa Mero were more similar, while Punta Brava resulted the most different. The variability in environmental conditions and the differential mass mortality effects of 1996 in all three reefs, were probably the main causes of the differences between their sponge communities. Nevertheless, we cannot conclude about the weight of these factors.

  12. Hydrogeologic framework and occurrence, movement, and chemical characterization of groundwater in Dixie Valley, west-central Nevada

    USGS Publications Warehouse

    Huntington, Jena M.; Garcia, C. Amanda; Rosen, Michael R.

    2014-01-01

    can be several orders of magnitude more transmissive than surrounding and underlying consolidated rocks and Dixie Valley playa deposits. Transmissivity estimates in the basin fill throughout Dixie Valley ranged from 30 to 45,500 feet squared per day; however, a single transmissivity value of 0.1 foot squared per day was estimated for playa deposits. Groundwater generally flows from the mountain range uplands toward the central valley lowlands and eventually discharges near the playa edge. Potentiometric contours east and west of the playa indicate that groundwater is moving eastward from the Stillwater Range and westward from the Clan Alpine Mountains toward the playa. Similarly, groundwater flows from the southern and northern basin boundaries toward the basin center. Subsurface groundwater flow likely enters Dixie Valley from Fairview and Stingaree Valleys in the south and from Jersey and Pleasant Valleys in the north, but groundwater connections through basin-fill deposits were present only across the Fairview and Jersey Valley divides. Annual subsurface inflow from Fairview and Jersey Valleys ranges from 700 to 1,300 acre-feet per year and from 1,800 to 2,300 acre-feet per year, respectively. Groundwater flow between Dixie, Stingaree, and Pleasant Valleys could occur through less transmissive consolidated rocks, but only flow through basin fill was estimated in this study. Groundwater in the playa is distinct from the freshwater, basin-fill aquifer. Groundwater mixing between basin-fill and playa groundwater systems is physically limited by transmissivity contrasts of about four orders of magnitude. Total dissolved solids in playa deposit groundwater are nearly 440 times greater than total dissolved solids in the basin-fill groundwater. These distinctive physical and chemical flow restrictions indicate that groundwater interaction between the basin fill and playa sediments was minimal during this study period (water years 2009–11). Groundwater in Dixie Valley

  13. Selected hydrologic data for the Bonneville Salt Flats and Pilot Valley, western Utah, 1991-93

    USGS Publications Warehouse

    Mason, James L.; Brothers, W.C.; Gerner, L.J.; Muir, P.S.

    1995-01-01

    This report contains hydrologic data collected during 1991-93 in the Bonneville Salt Flats and Pilot Valley study area of western Utah. These data were collected in cooperation with the U.S. Department of the Interior, Bureau of Land Management, as part of a study to investigate possible salt loss from the Bonneville Salt Flats. The Bonneville Salt Flats and adjacent Pilot Valley are located in the western part of the Great Salt Lake Desert in Utah, near the Nevada border. The Bonneville Salt Flats playa has a thick, perennial salt crust and the Pilot Valley playa has a thin, ephemeral salt crust. Well-completion data, including well depth and screened intervals, are presented in this report for selected shallow and deep monitoring wells. Water-level measurements are reported with corresponding specfic-gravity and temperature measurements. Results of chemical analyses are reported for brine collected from wells and pore fluids extracted from cores.

  14. Pesticide Use Plan (PUP) for Pantex Plant

    SciTech Connect

    Schoenhals, M.G.

    1995-12-31

    Federal Insecticide, Fungicide, and Rodenticide Act and its Worker Protection Standard, EPA authority, state regulations, and Texas Department of Agriculture authority make up a complex set of environment compliance requirements. The Pantex Plant northeast of Amarillo, Texas is currently dedicated to the disassembly of nuclear weapons. Ironically large areas of the Pantex Plant Site have been farmed for over 40 years. Pesticides are an integral part of agronomic production practices once economic thresholds for certain pests are exceeded. Horticulture and industrial operations also use pesticides. Pesticides can migrate to several playa lakes onsite, where they may threaten compliance with the Clean Water Act. Plant personnel are aware of the need to provide a chemically safe work environment, protect the public, and ensure an ecologically healthy environment. Thus a PUP has been developed to coordinate all pesticide use, ensure safety of agricultural and industrial workers, and protect the playa habitat. The PUP provides guidelines for pesticide use, notification, training, and safety.

  15. Groundwater discharge by evapotranspiration, Dixie Valley, west-central Nevada, March 2009-September 2011

    USGS Publications Warehouse

    Garcia, C. Amanda; Huntington, Jena M; Buto, Susan G.; Moreo, Michael T.; Smith, J. LaRue; Andraski, Brian J.

    2014-01-01

    Mean annual basin-scale ETg totaled about 28 million cubic meters (Mm3) (23,000 acre-feet [acre-ft]), and represents the sum of ETg from all ET units. Annual groundwater ET from vegetated areas totaled about 26 Mm3 (21,000 acre-ft), and was dominated by the moderate-to-dense shrubland ET unit (54 percent), followed by sparse shrubland (37 percent) and grassland (9 percent) ET units. Senesced grasses observed in the northern most areas of the moderate-to-dense ET unit likely confounded the vegetation index and led to an overestimate of ETg for this ET unit. Therefore, mean annual ETg for moderate-to-dense shrubland presented here is likely an upper bound. Annual groundwater ET from the playa ET unit was 2.2 Mm3 (1,800 acre-ft), whereas groundwater ET from the playa lake ET unit was 0&nd

  16. Reconnaissance investigation of brine in the eastern Rub al Khali, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Smith, C.L.

    1981-01-01

    Al Uruq al Mu'taridah-Umm as Samim area is located in a large topographic depression in the eastern Rub al Khali desert where playas several thousand square kilometers in area are exposedo A crust of eolian sand cemented with gypsum and halite has formed on many playa surfaces. Anhydrite nodules are common in the sampled area, where the depth to ground water generally exceeds 172 Cmo The chemistry of the three ground-water samples collected near the water well Ramallah-1 (lat 22?10'20'' N., long 54?20'37'' E.) is similar to that of sabkhah-related brines on the coast of the United Arab Emirates. Although there is no indication of economic quantities of evaporite minerals in the sampled area, the extent of the depression and its unique geologic environment recommend it for resource-evaluation studies.

  17. Arsenic and mercury contamination of sediments of geothermal springs, mangrove lagoon and the Santispac bight, Bahía Concepción, Baja California peninsula.

    PubMed

    Leal-Acosta, María Luisa; Shumilin, Evgueni; Mirlean, Nicolai; Sapozhnikov, Dmitry; Gordeev, Vyacheslav

    2010-12-01

    In order to find out the environmental impact on the coastal zone, the composition of sediments of the intertidal geothermal hot spring zone and adjacent area of Playa Santispac in the pristine Bahía Concepción (Baja California peninsula) was studied. High concentrations of As (13-111 mg kg⁻¹) and Hg (0.55-25.2 mg kg⁻¹) were found in the sediments of the geothermal sources. Arsenic and Hg concentrations decrease rapidly in the adjacent small mangrove lagoon sediments and reach background levels (0.7-2.6 mg kg⁻¹ and 6-60 μg kg⁻¹ respectively) in the marine sediments collected in front of Playa Santispac.

  18. NASA IKONOS Radiometric Characterization

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary; Ryan, Robert E.; Kelly, Michelle; Holekamp, Kara; Daehler, Erik; Zanoni, Vicki; Schiller, Stephen; Thome, Kurtis

    2002-01-01

    NASA acquired imagery from the IKONOS satellite as part of its Scientific Data Purchase (SDP) program, which purchases scientific data sets from commercial sources. This viewgraph presentation describes the IKONOS satellite and its sensors, and then gives an overview of characterization efforts undertaken by NASA in cooperation with other government agencies. The characterization included relative radiometric correction, absolute radiometric characterization of data from Lunar Lake Playa, Nevada, and calibration of data from Stennis Space Center, Mississippi.

  19. A 250,000-year record of lunette dune accumulation on the Southern High Plains, USA and implications for past climates

    NASA Astrophysics Data System (ADS)

    Rich, Julie

    2013-02-01

    A concentration of lake/playa basins occurs on the Southern High Plains (SHP) of northwest Texas and eastern New Mexico. Associated with these lake/playas are lee-side lunettes positioned on their southeast margins ranging in height from 1.5 to >10 m. An OSL dating program was applied to 30 samples from lunettes associated with large lakes and small playa basins. Samples were extracted from trenched dune sections or from deep cores. Earlier SHP lunette investigations show depositional ages primarily in the late Wisconsin and Holocene. This research extends the timing of lunette accretion to the middle Pleistocene, the earliest recorded deposition for these features. The expanded chronology permitted investigation into dune morphology on nested lunettes built on contracting lake margins. Outer lunettes formed prior to inner dunes, but simultaneous deposition occurred on downwind ridges as younger lee-side dunes were constructed. Large lake lunettes were inactive during discreet SHP pluvial episodes from early Wisconsin to LGM. Conversely, these lunettes accreted when climatic conditions promoted basin desiccation and aeolian deflation. This suggests their mode of formation contrasts with lunette models recognized for other regions. From post LGM to earliest Holocene, active lunette accretion occurred from 16 to 11 ka followed by a significant period of lunette construction during the mid-Holocene. Late Holocene-lunette deposition was interrupted by intervals of landscape stability. Lunette deposition between 1300s and 1700s corresponds with drought intervals recognized in tree-ring records from adjacent regions. Recent lunette activity on the plateau is contemporary with the 1930's 'dust bowl'. Further insight into SHP response to changing climatic conditions was given by comparing lunette depositional events with previous investigations on sedimentation intervals for draws, lake/playa basins, and sand sheets.

  20. Technical procedures for ecology: Environmental field program, Deaf Smith County Site, Texas: Final draft

    SciTech Connect

    Not Available

    1987-08-01

    This volume contains Technical Procedures pursuant to the Land Use Site Study Plan including walkover surveys for threatened, endangered, or candidate species; vegetation classification and mapping; reclamation planning; wetland and floodplain determination and characterization of playas; wildlife habitat mapping methods; mammal sampling; bird survey methods; reptile and amphibian survey methods; preexisting environmental; stress and disturbance studies methods; voucher specimens for plants; and voucher specimens to wildlife. 9 refs., 5 figs., 1 tab.

  1. AVIRIS study of Death Valley evaporite deposits using least-squares band-fitting methods

    NASA Technical Reports Server (NTRS)

    Crowley, J. K.; Clark, R. N.

    1992-01-01

    Minerals found in playa evaporite deposits reflect the chemically diverse origins of ground waters in arid regions. Recently, it was discovered that many playa minerals exhibit diagnostic visible and near-infrared (0.4-2.5 micron) absorption bands that provide a remote sensing basis for observing important compositional details of desert ground water systems. The study of such systems is relevant to understanding solute acquisition, transport, and fractionation processes that are active in the subsurface. Observations of playa evaporites may also be useful for monitoring the hydrologic response of desert basins to changing climatic conditions on regional and global scales. Ongoing work using Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data to map evaporite minerals in the Death Valley salt pan is described. The AVIRIS data point to differences in inflow water chemistry in different parts of the Death Valley playa system and have led to the discovery of at least two new North American mineral occurrences. Seven segments of AVIRIS data were acquired over Death Valley on 31 July 1990, and were calibrated to reflectance by using the spectrum of a uniform area of alluvium near the salt pan. The calibrated data were subsequently analyzed by using least-squares spectral band-fitting methods, first described by Clark and others. In the band-fitting procedure, AVIRIS spectra are fit compared over selected wavelength intervals to a series of library reference spectra. Output images showing the degree of fit, band depth, and fit times the band depth are generated for each reference spectrum. The reference spectra used in the study included laboratory data for 35 pure evaporite spectra extracted from the AVIRIS image cube. Additional details of the band-fitting technique are provided by Clark and others elsewhere in this volume.

  2. Surface processes on Venus

    NASA Technical Reports Server (NTRS)

    Arvidson, R. E.

    1992-01-01

    Magellan synthetic aperture radar (SAR) and altimetry data were analyzed to determine the nature and extent of surface modification for venusian plains in the Sedna Planitia, Alpha Regio, and western Ovda Regio areas. Specific cross sections derived from the SAR data were also compared to similar data for dry terrestrial basaltic lava flows (Lunar Crater and Cima volcanic fields) and playas (Lunar and Lavic Lakes) for which microtopographic profiles (i.e., quantitative roughness information) were available.

  3. Field investigation of dried lakes in western United States as an analogue to desiccation fractures on Mars

    NASA Astrophysics Data System (ADS)

    El-Maarry, M. R.; Watters, W. A.; Yoldi, Z.; Pommerol, A.; Fischer, D.; Eggenberger, U.; Thomas, N.

    2015-12-01

    Potential Desiccation Polygons (PDPs), tens to hundreds of meters in size, have been observed in numerous regions on Mars, particularly in ancient (>3 Gyr old) terrains of inferred paleolacustrine/playa geologic setting, and in association with hydrous minerals such as smectites. Therefore, a better understanding of the conditions in which large desiccation polygons form could yield unique insight into the ancient climate on Mars. Many dried lakebeds/playas in western United States display large (>50 m wide) desiccation polygons, which we consider to be analogues for PDPs on Mars. Therefore, we have carried out fieldwork in seven of these dried lakes in San Bernardino and the Death Valley National Park regions complemented with laboratory and spectral analysis of collected samples. Our study shows that the investigated lacustrine/playa sediments have (a) a soil matrix containing ~40-75% clays and fine silt (by volume) where the clay minerals are dominated by illite/muscovite followed by smectite, (b) carbonaceous mineralogy with variable amounts of chloride and sulfate salts, and significantly, (c) roughly similar spectral signatures in the visible-near-infrared (VIS-NIR) range. We conclude that the development of large desiccation fractures is consistent with water table retreat. In addition, the comparison of the mineralogical to the spectral observations further suggests that remote sensing VIS-NIR spectroscopy has its limitations for detailed characterization of lacustrine/playa deposits. Finally, our results imply that the widespread distribution of PDPs on Mars indicates global or regional climatic transitions from wet conditions to more arid ones making them important candidate sites for future in situ missions.

  4. Megabreccia deposits in an extensional basin: The Miocene-Pliocene Horse Camp Formation, east-central Nevada

    SciTech Connect

    Schmitt, J.G.; Brown, C.L. )

    1991-06-01

    Three varieties of megabreccia deposits are present in alluvial-lacustrine extensional basin fill of the Miocene-Pliocene Horse Camp Formation of east-central Nevada. Coherent debris sheets (150-300 m thick; up to 1,500 m long) consist of Oligocene-Miocene volcanic rock masses which are internally fractured yet retain their stratigraphic integrity. Fracture zones show variable amounts of displacement (up to 5 cm) and brecciation. These debris sheets overlie horizontally stratified sandstone and laminated claystone interpreted as playa deposits and are overlain by lithified grus. Emplacement of these coherent debris sheets was by landslide or block slide. Associated deposits of large boulders within playa facies suggest gliding of blocks broken from the edges of the landslides across wet playa surfaces. Large (1.6 - 2.4 km-long) allochthonous blocks consist of intact Paleozoic and Tertiary volcanic stratigraphic sequences which are brecciated and attenuated. Brecciation is accompanied in places by incorporation of muddy sand matrix. These blocks may be fragments of the upper plate of low-angle detachment faults which broke away as gravity-driven blocks from the nearby Horse Range and slid along the uplifted former detachment surface into the adjacent Horse Camp basin. Megabreccia deposits characterize Teritary extensional basins in western North America. Detailed analysis of their stratigraphic, sedimentologic, and structural relations can provide a better understanding of the complex tectonosedimentary history of these basins.

  5. Megaliths and Neolithic astronomy in southern Egypt

    NASA Astrophysics Data System (ADS)

    Malville, J. Mckim; Wendorf, Fred; Mazar, Ali A.; Schild, Romauld

    1998-04-01

    The Sahara west of the Nile in southern Egypt was hyperarid and unoccupied during most of the Late Pleistocene epoch. About 11,000 years ago the summer monsoons of central Africa moved into Egypt, and temporary lakes or playas were formed. The Nabta Playa depression, which is one of the largest in southern Egypt, is a kidney-shaped basin of roughly 10km by 7km in area. We report the discovery of megalithic alignments and stone circles next to locations of Middle and Late Neolithic communities at Nabta, which suggest the early development of a complex society. The southward shift of the monsoons in the Late Neolithic age rendered the area once again hyperarid and uninhabitable some 4,800 radiocarbon years before the present (years BP). This well-determined date establishes that the ceremonial complex of Nabta, which has alignments to cardinal and solstitial directions, was a very early megalithic expression of ideology and astronomy. Five megalithic alignments within the playa deposits radiate outwards from megalithic structures, which may have been funerary structures. The organization of the megaliths suggests a symbolic geometry that integrated death, water, and the Sun. An exodus from the Nubian Desert at ~4,800 years BP may have stimulated social differentiation and cultural complexity in predynastic Upper Egypt.

  6. Assessment of the effects of farming and conservation programs on pesticide deposition in high plains wetlands.

    PubMed

    Belden, Jason B; Hanson, Brittany Rae; McMurry, Scott T; Smith, Loren M; Haukos, David A

    2012-03-20

    We examined pesticide contamination in sediments from depressional playa wetlands embedded in the three dominant land-use types in the western High Plains and Rainwater Basin of the United States including cropland, perennial grassland enrolled in conservation programs (e.g., Conservation Reserve Program [CRP]), and native grassland or reference condition. Two hundred and sixty four playas, selected from the three land-use types, were sampled from Nebraska and Colorado in the north to Texas and New Mexico in the south. Sediments were examined for most of the commonly used agricultural pesticides. Atrazine, acetochlor, metolachlor, and trifluralin were the most commonly detected pesticides in the northern High Plains and Rainwater Basin. Atrazine, metolachlor, trifluralin, and pendimethalin were the most commonly detected pesticides in the southern High Plains. The top 5-10% of playas contained herbicide concentrations that are high enough to pose a hazard for plants. However, insecticides and fungicides were rarely detected. Pesticide occurrence and concentrations were higher in wetlands surrounded by cropland as compared to native grassland and CRP perennial grasses. The CRP, which is the largest conservation program in the U.S., was protective and had lower pesticide concentrations compared to cropland.

  7. Effects of the Conservation Reserve Program on Hydrologic Processes in the Southern High Plains

    NASA Astrophysics Data System (ADS)

    Haacker, E. M.; Smidt, S. J.; Kendall, A. D.; Basso, B.; Hyndman, D. W.

    2015-12-01

    The Southern High Plains Aquifer is a rapidly depleting resource that supports agriculture in parts of New Mexico and the Texas Panhandle. The development of the aquifer has changed the landscape and the water cycle of the region. This study illustrates the evolving patterns of land use and the effects of cultivation, from irrigated to dryland farming to the countermanding influence of the Conservation Reserve Program (CRP). Previous research indicates that greater recharge rates occur under cultivated land in the Southern High Plains than under unbroken soil: the transition to cultivation causes increased recharge, under both dryland and irrigated management, though most recharge still occurs through playa lakes. The Conservation Reserve Program takes land out of crop production, replacing the land cover with something more like the natural ecosystem. This may decrease recharge below fields, and reduce runoff that feeds playa lakes; or, CRP may help stabilize playa lakes, increasing recharge. Changes to the water cycle are investigated at the field scale using the System Approach to Land Use Sustainability (SALUS) crop model, and at the regional scale with the Landscape Hydrology Model (LHM), and compared with historical data and water table elevations.

  8. Simultaneous observations of the critical aeolian threshold of two surfaces

    NASA Astrophysics Data System (ADS)

    Stout, John E.

    2007-03-01

    Threshold is an important parameter in wind erosion research and in the field of aeolian research in general. A new technique was recently developed that provides a means of determining threshold with a sampling system that continuously collects wind data along with critical information regarding saltation activity. By employing two identical sampling systems, it was possible to monitor the threshold of a highly mobile sand surface while simultaneously monitoring the threshold of a less mobile playa surface. Results indicate that threshold could be measured at both locations with enough precision to establish clear differences between the surfaces. The sandy surface at the Morgenstern Dunes site was considerably more active than the Yellow Lake playa site over the 113-day sampling period because of its consistently lower threshold. The Morgenstern site tended to maintain a fairly constant threshold of around 5.4 to 5.5 m/s whereas the threshold of the Yellow Lake playa surface varied from a low of 6.4 m/s to values greater than 13.3 m/s. Limitations of this method lie in the fact that threshold can be determined only when winds are blowing sufficiently strongly to cause sediment transport.

  9. Lithium- and boron-bearing brines in the Central Andes: exploring hydrofacies on the eastern Puna plateau between 23° and 23°30'S

    NASA Astrophysics Data System (ADS)

    Steinmetz, R. L. López

    2016-04-01

    Internally drained basins of the Andean Plateau are lithium- and boron-bearing systems. The exploration of ionic facies and parental links in a playa lake located in the eastern Puna (23°-23°30'S) was assessed by hydrochemical determinations of residual brines, feed waters and solutions from weathered rocks. Residual brines have been characterized by the Cl- (SO4 =)/Na+ (K+) ratio. Residual brines from the playa lake contain up to 450 mg/l of boron and up to 125 mg/l of lithium, and the Las Burras River supplies the most concentrated boron (20 mg/l) and lithium (3.75 mg/l) inflows of the basin. The hydro-geochemical assessment allowed for the identification of three simultaneous sources of boron: (1) inflow originating from granitic areas of the Aguilar and Tusaquillas ranges; (2) weathering of the Ordovician basement; and (3) boron-rich water from the Las Burras River. Most of the lithium input of the basin is likely generated by present geothermal sources rather than by weathering and leaching of ignimbrites and plutonic rocks. However, XRD analyses of playa lake sediments revealed the presence of lithian micas of clastic origin, including taeniolite and eucriptite. This study is the first to document these rare Li-micas from the Puna basin. Thus, both residual brines and lithian micas contribute to the total Li content in the studied hydrologic system.

  10. Observation of the geology and geomorphology of the 1999 Marsokhod test site

    USGS Publications Warehouse

    De Hon, R. A.; Barlow, N.G.; Reagan, M.K.; Bettis, E. Arthur; Foster, C.T.; Gulick, V.C.; Crumpler, L.S.; Aubele, J.C.; Chapman, M.G.; Tanaka, K.L.

    2001-01-01

    The Marsokhod rover returned data from six stations that were used to decipher the geomorphology and geology of a region not previously visited by members of the geomorphology field team. Satellite images and simulated descent images provided information about the regional setting. The landing zone was on an alluvial apron flanking a mountain block to the west and a playa surface to the east. Rover color images, infrared spectra analysis of the mountains, and the apron surface provided insight into the rock composition of the nearby mountains. From the return data the geomorphology team interpreted the region to consist of compressionally deformed, ancient marine sediments and igneous rocks exposed by more recent extensional tectonics. Unconsolidated alluvial materials blanket the lower flanks of the mountains. An ancient shoreline cut into alluvial material marks a high stand of water during a past, wetter climate period. Playa sediments floor a present-day, seasonally, dry lake. Observations made by the rover using panoramic and close-up (hand specimens-scale) image data and color scene data confirmed the presence of boulders, cobbles, and fines of various provinces. Rover traverses to sites identified as geologically distinct, such as fan, channel, shoreline, and playa, provided useful clues to the geologic interpretations. Analysis of local rocks was given context only through comparison with distant geologic features. These results demonstrated the importance of a multifaceted approach to site interpretation through comparison of interpretations derived by differing geologic techniques. Copyright 2001 by the American Geophysical Union.

  11. Assessment of the effects of farming and conservation programs on pesticide deposition in high plains wetlands.

    PubMed

    Belden, Jason B; Hanson, Brittany Rae; McMurry, Scott T; Smith, Loren M; Haukos, David A

    2012-03-20

    We examined pesticide contamination in sediments from depressional playa wetlands embedded in the three dominant land-use types in the western High Plains and Rainwater Basin of the United States including cropland, perennial grassland enrolled in conservation programs (e.g., Conservation Reserve Program [CRP]), and native grassland or reference condition. Two hundred and sixty four playas, selected from the three land-use types, were sampled from Nebraska and Colorado in the north to Texas and New Mexico in the south. Sediments were examined for most of the commonly used agricultural pesticides. Atrazine, acetochlor, metolachlor, and trifluralin were the most commonly detected pesticides in the northern High Plains and Rainwater Basin. Atrazine, metolachlor, trifluralin, and pendimethalin were the most commonly detected pesticides in the southern High Plains. The top 5-10% of playas contained herbicide concentrations that are high enough to pose a hazard for plants. However, insecticides and fungicides were rarely detected. Pesticide occurrence and concentrations were higher in wetlands surrounded by cropland as compared to native grassland and CRP perennial grasses. The CRP, which is the largest conservation program in the U.S., was protective and had lower pesticide concentrations compared to cropland. PMID:22356096

  12. Geochemical evidence for diversity of dust sources in the southwestern United States

    USGS Publications Warehouse

    Reheis, M.C.; Budahn, J.R.; Lamothe, P.J.

    2002-01-01

    Several potential dust sources, including generic sources of sparsely vegetated alluvium, playa deposits, and anthropogenic emissions, as well as the area around Owens Lake, California, affect the composition of modern dust in the southwestern United States. A comparison of geochemical analyses of modern and old (a few thousand years) dust with samples of potential local sources suggests that dusts reflect four primary sources: (1) alluvial sediments (represented by Hf, K, Rb, Zr, and rare-earth elements, (2) playas, most of which produce calcareous dust (Sr, associated with Ca), (3) the area of Owens (dry) Lake, a human-induced playa (As, Ba, Li, Pb, Sb, and Sr), and (4) anthropogenic and/or volcanic emissions (As, Cr, Ni, and Sb). A comparison of dust and source samples with previous analyses shows that Owens (dry) Lake and mining wastes from the adjacent Cerro Gordo mining district are the primary sources of As, Ba, Li, and Pb in dusts from Owens Valley. Decreases in dust contents of As, Ba, and Sb with distance from Owens Valley suggest that dust from southern Owens Valley is being transported at least 400 km to the east. Samples of old dust that accumulated before European settlement are distinctly lower in As, Ba, and Sb abundances relative to modern dust, likely due to modern transport of dust from Owens Valley. Thus, southern Owens Valley appears to be an important, geochemically distinct, point source for regional dust in the southwestern United States. Copyright ?? 2002 Elsevier Science Ltd.

  13. 1. GENERAL VIEW OF THE BRIDGE, THE RIVER, AND AN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. GENERAL VIEW OF THE BRIDGE, THE RIVER, AND AN OLD SEGMENT OF THE SAN LORENZO-LAS PIEDRAS HIGHWAY FROM THE NORTH. - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  14. 6. SOUTHWEST SIDE PARTIAL ELEVATION OF NORTHWESTERN HALF OF THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. SOUTHWEST SIDE -PARTIAL ELEVATION OF NORTHWESTERN HALF OF THE BRIDGE, FROM THE NEW BRIDGE - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  15. 11. DETAIL: OBLIQUE VIEW FROM SOUTHWEST OF TYPICAL SPAN SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. DETAIL: OBLIQUE VIEW FROM SOUTHWEST OF TYPICAL SPAN SHOWING ART DECO RELIEFS AND REMAINS OF BRACKETS FOR SUPPORTING STEEL SIDEWALKS. - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  16. 8. SOUTHWEST SIDE PARTIAL ELEVATION OF SOUTHEASTERN QUARTER OF THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. SOUTHWEST SIDE -PARTIAL ELEVATION OF SOUTHEASTERN QUARTER OF THE BRIDGE FROM HILL, SHOWING THE QUEBRADA PUERCO BROOK. - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  17. 7. Oblique partial view of the bridge with its modified ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Oblique partial view of the bridge with its modified eastern end's box culverts and a part of the causeway, from the new bridge and the northeast. - Puente del Caño Perdomo, Route PR-2 spanning Cano Perdomo Channel, Arecibo, Arecibo Municipio, PR

  18. 2. GENERAL VIEW OF THE BRIDGE, THE RIVER, AND THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. GENERAL VIEW OF THE BRIDGE, THE RIVER, AND THE MARINA SECTOR OF SAN LORENZO FROM THE SOUTH. - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  19. Photocopy of photograph (original 35 millimeter negative in possession of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original 35 millimeter negative in possession of Luis Pumarada, San German, Puerto Rico). Luis Pumarada, Photographer, September 4, 1989. PUENTE RIO HONDO, DOMED PLATE DECK FROM BELOW. - Puente Rio Hondo, Spanning Hondo River on PR Road 156, Barrio Rio Hondo, Comerio, Comerio Municipio, PR

  20. 7. SOUTHWEST SIDE PARTIAL ELEVATION OF SOUTHEASTERN INNER QUARTER OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. SOUTHWEST SIDE -PARTIAL ELEVATION OF SOUTHEASTERN INNER QUARTER OF THE BRIDGE FROM HILL - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  1. Photocopy of photograph (original 35 millimeter negative in possession of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original 35 millimeter negative in possession of Luis Pumarada, San German, Puerto Rico). Luis Pumarada, Photographer, September 4, 1989. PUENTE RIO HONDO, VIEW OF SOUTH ABUTMENT. - Puente Rio Hondo, Spanning Hondo River on PR Road 156, Barrio Rio Hondo, Comerio, Comerio Municipio, PR

  2. Photocopy of photograph (original 35 millimeter negative in possession of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original 35 millimeter negative in possession of Luis Pumarada, San German, Puerto Rico). Luis Pumarada, Photographer, September 4, 1989. PUENTE RIO HONDO, VIEW FROM SOUTHWEST. - Puente Rio Hondo, Spanning Hondo River on PR Road 156, Barrio Rio Hondo, Comerio, Comerio Municipio, PR

  3. Up, down, and across the Land: Landscape Terms, Place Names, and Spatial Language in Tzeltal

    ERIC Educational Resources Information Center

    Brown, Penelope

    2008-01-01

    The Tzeltal language is spoken in a mountainous region of southern Mexico by some 280,000 Mayan corn farmers. This paper focuses on landscape and place vocabulary in the Tzeltal municipio of Tenejapa, where speakers use an absolute system of spatial reckoning based on the overall uphill (southward)/downhill (northward) slope of the land. The paper…

  4. [The city of Puebla in the regional context. I:ndustrialization and marginality].

    PubMed

    Velez Pliego, F M

    1994-01-01

    The city of Puebla concentrates 25.6% of the total population of the state of Puebla, 30% of its employed population, 42% of its secondary sector workers, and 52% of its tertiary sector workers. Puebla has historically been an intermediate point between Mexico City and the states of Veracruz, Chiapas, Tabasco, and Oaxaca. Its geographic location and importance as a pioneer in the country's textile industry and later its industrial diversification have allowed Puebla to be functionally complementary to Mexico City. Puebla's regional influence and territorial integration of neighboring areas are increasing. State governments of Puebla over the past 30 years have promoted these tendencies as a means of fortifying Puebla's economic and political position. Puebla's municipal boundaries have been expanding since 1960 to accommodate industrial parks and an industrial corridor along the Mexico City-Puebla highway. The boundaries have moved outward to incorporate urbanized neighboring settlements. Intraregional development has benefited the municipio of Puebla more than its neighbors. Puebla is the only municipio in the region considered to exhibit a very low degree of marginality. In the past 20 years, the 14 municipios in the region have nearly doubled their population, from 728,974 to 1,445,447 inhabitants. The municipio of Puebla has maintained a relative weight of about 73% of the regional total. Current trends suggest that Puebla's relative demographic importance will decline within the region. The ongoing diversification of economic activities should tend to reduce intraregional disparities.

  5. Xalacapan: Village and School in Zacapoaxtla, Puebla.

    ERIC Educational Resources Information Center

    Trueba, Enrique Torres

    Situated on the Sierra Madre's western slope is Zacapoaxtla, one of the 222 municipios in the State of Puebla, Mexico. From prehispanic times, Zacapoaxtla has been a "region de refugio" where groups of American Indians cluster, isolate themselves from the rest of the world, and maintain their cultural traditions insofar as the national economic…

  6. 1. Straighton view looking S at sugar cane crushing machinery ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Straight-on view looking S at sugar cane crushing machinery showing three-roll cane mill, single reduction gear, flywheel and steam engine. - Hacienda Azucarera la Igualdad, Sugar Mill Ruins & Steam Engine, PR Route 332, Guanica, Guanica Municipio, PR

  7. 1. Front view of steam engine and mill, looking NE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Front view of steam engine and mill, looking NE, showing (l to r) 6-column beam engine, flywheel, reduction gears and 3-roll cane mill. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  8. 23. General view of the top gundeck looking northwest from ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. General view of the top gundeck looking northwest from Austria Bastion showing ramp down and parapet wall of the Plaza de Armas on lower level - Castillo de San Felipe del Morro, Northwest end of San Juan, San Juan, San Juan Municipio, PR

  9. 2. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, 1956 ELEVATION OF CHAPEL AND SALLY PORT TOWARDS THE COURTYARD PLAZA DE ARMAS, SAN FELIPE DEL MORRO. - Castillo de San Felipe del Morro Sally Port & Chapel, Northwest end of San Juan Island, San Juan, San Juan Municipio, PR

  10. 37. Closeup of stairs in previous photo, leading up to ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. Close-up of stairs in previous photo, leading up to El Macho and down to Plaza de Armas, from Santa Barbara Bastion, viewed from northwest - Castillo de San Felipe del Morro, Northwest end of San Juan, San Juan, San Juan Municipio, PR

  11. 10. View looking S at large arched opening that led ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. View looking S at large arched opening that led from area where Jamaican Train was fired to steam engine and cane mill. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  12. 1988 Work Papers of the Summer Institute of Linguistics, University of North Dakota Session. Volume 32.

    ERIC Educational Resources Information Center

    Derbyshire, Desmond C., Ed.

    Six working papers in linguistics are presented. "The Semantics and Morphology of Mixtec Mood and Aspect" (J. Albert Bickford and Stephen A. Marlett) presents a relatively detailed description of the following grammatical categories in three Mixtec languages: Santiago Nuyoo, Santo Domingo Nuxaa, and Municipio of Tezoatlan. "Nonsyllabic Vocoids"…

  13. 2. General view of guard house and entrance to Coast ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. General view of guard house and entrance to Coast Guard Base from La Putilla Street, with view of Motor Pool (Building 122) on right side looking west - U.S. Coast Guard Base, San Juan, Guard House, La Puntilla Finalle, San Juan, San Juan Municipio, PR

  14. 49. Detail of top wall in S room showing two ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    49. Detail of top wall in S room showing two beam tie-backs. - Hacienda Azurarera Santa Elena, Sugar Mill Ruins, 1.44 miles North of PR Route 2 Bridge Over Rio De La Plata, Toa Baja, Toa Baja Municipio, PR

  15. 48. Detail of top of wall in S room showing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    48. Detail of top of wall in S room showing strap-iron beam tie-back anchored in wall with severely deteriorated beam in place. - Hacienda Azurarera Santa Elena, Sugar Mill Ruins, 1.44 miles North of PR Route 2 Bridge Over Rio De La Plata, Toa Baja, Toa Baja Municipio, PR

  16. Photocopy of photograph (original print located in Archivo General de ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original print located in Archivo General de Puerto Rico, San Juan, PR). CAISSON GATE GENERAL PLANS Dwg. 38-SJ-29 - Graving Dock, Caisson Gate, Southern end of Central Street bounded by Villaverde and La Paz Streets, Miramar, San Juan Municipio, PR

  17. Photocopy of photograph (original print located in Archivo General de ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original print located in Archivo General de Puerto Rico, San Juan, PR). CAISSON GATE FABRICATION PHOTO DATED 1-9-40 - Graving Dock, Caisson Gate, Southern end of Central Street bounded by Villaverde and La Paz Streets, Miramar, San Juan Municipio, PR

  18. Photocopy of photograph (original print located in Archivo General de ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original print located in Archivo General de Puerto Rico, San Juan, PR). CAISSON GATE FABRICATION PHOTO DATED APRIL 6, 1941 - Graving Dock, Caisson Gate, Southern end of Central Street bounded by Villaverde and La Paz Streets, Miramar, San Juan Municipio, PR

  19. Photocopy of photograph (original print located in Archivo General de ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original print located in Archivo General de Puerto Rico, San Juan, PR). PHYSICAL SETTING VIEW TO SOUTHWEST DATED 12-2-40 - Graving Dock, Caisson Gate, Southern end of Central Street bounded by Villaverde and La Paz Streets, Miramar, San Juan Municipio, PR

  20. Photocopy of photograph (original print located in Archivo General de ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original print located in Archivo General de Puerto Rico, San Juan, PR). GENERAL PLAN ELEVATION SHOWING GENERAL DETAILS - Graving Dock, Caisson Gate, Southern end of Central Street bounded by Villaverde and La Paz Streets, Miramar, San Juan Municipio, PR

  1. 40. Coffee bean drying trays that are stored in racks ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    40. Coffee bean drying trays that are stored in racks under building and pulled out to sun dry beans on terraces to the north and south of building. HAER PR, 6-MAGU, 1C-3 - Hacienda Buena Vista, PR Route 10 (Ponce to Arecibo), Magueyes, Ponce Municipio, PR

  2. 38. East elevation of coffee storage and drying shed with ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    38. East elevation of coffee storage and drying shed with circular, cattle watering pond in left foreground and coffee mill in background right. HAER PR, 6-MAGU, 1C-1 - Hacienda Buena Vista, PR Route 10 (Ponce to Arecibo), Magueyes, Ponce Municipio, PR

  3. Analysis and prediction of dryland land-surface processes and their influence on the meteorology of the Intermountain West

    NASA Astrophysics Data System (ADS)

    Massey, Jeffrey Duffus

    This dissertation examines the performance of Weather Research and Forecasting (WRF) model near-surface temperature and surface energy balance forecasts over Dugway Proving Ground (DPG) in northwest Utah during the Mountain Terrain Atmospheric Modeling and Observations Program (MATERHORN) field campaigns. This region of complex terrain has two distinct land surfaces, playa and sparsely vegetated desert shrub, which are common in other dryland regions. Operational WRF forecasts show persistent underprediction of the diurnal temperature range due to a nighttime warm bias and a daytime cold bias. The former is especially strong over the desert shrub. The nighttime warm bias can be improved through the utilization of in situ soil moisture observations and by replacing Johansen's 1975 parameterization of soil thermal conductivity in the Noah land surface model with that proposed by McCumber and Pielke in 1981 for silt loam and sandy loam soils. The daytime cold bias extends from the surface to above the top of the planetary boundary layer and is primarily caused by a regional overestimation of near-surface soil-moisture in operational land-surface analyses, which do not currently assimilate in situ soil-moisture observations. Bias correction of the soil-moisture analyses across the Intermountain West using North American Soil Moisture Database observations reduces the daytime cold bias. Utilization of observed soil moisture and the McCumber and Pielke soil thermal conductivity parameterization also improves the surface energy balance forecast over the desert shrub, but degrades it over the playa. Land surface processes unique to the playa are not currently accounted for in the Noah land surface model. Nevertheless, a larger and more accurate temperature gradient develops between the playa and desert shrub that forces a stronger daytime off-playa breeze. However, 10-m wind speed and direction forecasts show limited statistically significant improvement. This dissertation

  4. Hydrogeologic framework and occurrence, movement, and chemical characterization of groundwater in Dixie Valley, west-central Nevada

    USGS Publications Warehouse

    Huntington, Jena M.; Garcia, C. Amanda; Rosen, Michael R.

    2014-01-01

    can be several orders of magnitude more transmissive than surrounding and underlying consolidated rocks and Dixie Valley playa deposits. Transmissivity estimates in the basin fill throughout Dixie Valley ranged from 30 to 45,500 feet squared per day; however, a single transmissivity value of 0.1 foot squared per day was estimated for playa deposits. Groundwater generally flows from the mountain range uplands toward the central valley lowlands and eventually discharges near the playa edge. Potentiometric contours east and west of the playa indicate that groundwater is moving eastward from the Stillwater Range and westward from the Clan Alpine Mountains toward the playa. Similarly, groundwater flows from the southern and northern basin boundaries toward the basin center. Subsurface groundwater flow likely enters Dixie Valley from Fairview and Stingaree Valleys in the south and from Jersey and Pleasant Valleys in the north, but groundwater connections through basin-fill deposits were present only across the Fairview and Jersey Valley divides. Annual subsurface inflow from Fairview and Jersey Valleys ranges from 700 to 1,300 acre-feet per year and from 1,800 to 2,300 acre-feet per year, respectively. Groundwater flow between Dixie, Stingaree, and Pleasant Valleys could occur through less transmissive consolidated rocks, but only flow through basin fill was estimated in this study. Groundwater in the playa is distinct from the freshwater, basin-fill aquifer. Groundwater mixing between basin-fill and playa groundwater systems is physically limited by transmissivity contrasts of about four orders of magnitude. Total dissolved solids in playa deposit groundwater are nearly 440 times greater than total dissolved solids in the basin-fill groundwater. These distinctive physical and chemical flow restrictions indicate that groundwater interaction between the basin fill and playa sediments was minimal during this study period (water years 2009–11). Groundwater in Dixie Valley

  5. Estimated ground-water discharge by evapotranspiration from Death Valley, California, 1997-2001

    USGS Publications Warehouse

    DeMeo, Guy A.; Laczniak, Randell J.; Boyd, Robert A.; Smith, J. LaRue; Nylund, Walter E.

    2003-01-01

    The U.S. Geological Survey, in cooperation with the National Park Service and Inyo County, Calif., collected field data from 1997 through 2001 to accurately estimate the amount of annual ground-water discharge by evapotranspiration (ET) from the floor of Death Valley, California. Multispectral satellite-imagery and National Wetlands Inventory data are used to delineate evaporative ground-water discharge areas on the Death Valley floor. These areas are divided into five general units where ground-water discharge from ET is considered to be significant. Based upon similarities in soil type, soil moisture, vegetation type, and vegetation density; the ET units are salt-encrusted playa (21,287 acres), bare-soil playa (75,922 acres), low-density vegetation (6,625 acres), moderate-density vegetation (5,019 acres), and high-density vegetation (1,522 acres). Annual ET was computed for ET units with micrometeorological data which were continuously measured at six instrumented sites. Total ET was determined at sites that were chosen for their soil- and vegetated-surface conditions, which include salt-encrusted playa (extensive salt encrustation) 0.17 feet per year, bare-soil playa (silt and salt encrustation) 0.21 feet per year, pickleweed (pickleweed plants, low-density vegetation) 0.60 feet per year, Eagle Borax (arrowweed plants and salt grass, moderate-density vegetation) 1.99 feet per year, Mesquite Flat (mesquite trees, high-density vegetation) 2.86 feet per year, and Mesquite Flat mixed grasses (mixed meadow grasses, high-density vegetation) 3.90 feet per year. Precipitation, flooding, and ground-water discharge satisfy ET demand in Death Valley. Ground-water discharge is estimated by deducting local precipitation and flooding from cumulative ET estimates. Discharge rates from ET units were not estimated directly because the range of vegetation units far exceeded the five specific vegetation units that were measured. The rate of annual ground-water discharge by ET for

  6. A 16-year record of eolian dust in Southern Nevada and California, USA: Controls on dust generation and accumulation

    USGS Publications Warehouse

    Reheis, M.C.

    2006-01-01

    An ongoing project monitors modern dust accumulation in the arid southwestern United States to (1) determine the rate and composition of dust inputs to soils and (2) relate dust accumulation to weather patterns to help predict the effects of climate change on dust production and accumulation. The 16-year records of 35 dust-trap sites in the eastern Mojave Desert and southern Great Basin reveal how generation and accumulation of dust, including the silt-clay, carbonate, and soluble-salt fractions, is affected by the amount and seasonal distribution of rainfall and the behavior of different source types (alluvium, dry playas, and wet playas). Accumulation rates (fluxes) of the silt-clay fraction of dust, including carbonates, range from about 2-20 g/m2/yr. Average rates are higher in the southern part of the study area (south of latitude 36.5??N) and annually fluctuate over a larger range than rates in the northern part of the area. Sites throughout the study area show peaks in dust flux in the 1984-1985 sampling period and again in 1997-1999; northern sites also show increased flux in 1987-1988 and southern sites in 1989-1991. These peaks of dust flux correspond with both La Nina (dry) conditions and with strong El Nino (wet) periods. The accumulation rates of different components of mineral dusts fluctuate differently. For example, soluble-salt flux increases in 1987-1988, coincident with a moderate El Nino event, and increases very strongly in 1997-1999, overlapping with a strong El Nino event. Both of these high-rainfall winters were preceded and accompanied by strong summer rains. In contrast, little or no change in soluble-salt flux occurred during other periods of high winter rainfall but little summer rain, e.g. 1992-1995. The differences between northern vs. southern sites and between sites with playa dust sources vs. alluvial dust sources indicate that regional differences in the response of precipitation and vegetation growth to ENSO influence and

  7. A 16,000 14C yr B.P. packrat midden series from the USA-Mexico Borderlands

    USGS Publications Warehouse

    Holmgren, C.A.; Penalba, M.C.; Rylander, K.A.; Betancourt, J.L.

    2003-01-01

    A new packrat midden chronology from Playas Valley, southwestern New Mexico, is the first installment of an ongoing effort to reconstruct paleovegetation and paleoclimate in the U.S.A.-Mexico Borderlands. Playas Valley and neighboring basins supported pluvial lakes during full and/or late glacial times. Plant macrofossil and pollen assemblages from nine middens in the Playas Valley allow comparisons of two time intervals: 16,000-10,000 and 4000-0 14C yr B.P. Vegetation along pluvial lake margins consisted of open pinyon-juniper communities dominated by Pinus edulis, Juniperus scopulorum, Juniperus cf. coahuilensis, and a rich understory of C4 annuals and grasses. This summer-flowering understory is also characteristic of modern desert grassland in the Borderlands and indicates at least moderate summer precipitation. P. edulis and J. scopulorum disappeared or were rare in the midden record by 10,670 14C yr B.P. The late Holocene is marked by the arrival of Chihuahuan desert scrub elements and few departures as the vegetation gradually became modern in character. Larrea tridentata appears as late as 2190 14C yr B.P. based on macrofossils, but may have been present as early as 4095 14C yr B.P. based on pollen. Fouquieria splendens, one of the dominant desert species present at the site today, makes its first appearance only in the last millennium. The midden pollen assemblages are difficult to interpret; they lack modern analogs in surface pollen assemblages from stock tanks at different elevations in the Borderlands. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  8. Assessment of waterlogging in agricultural megaprojects in the closed drainage basins of the Western Desert of Egypt

    NASA Astrophysics Data System (ADS)

    El Bastawesy, M.; Ramadan Ali, R.; Faid, A.; El Osta, M.

    2013-04-01

    This paper investigates the development of waterlogging in the cultivated and arable areas within typical dryland closed drainage basins (e.g. the Farafra and Baharia Oases), which are located in the Western Desert of Egypt. Multi-temporal remote sensing data of the Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) were collected and processed to detect the land cover changes; cultivations, and the extent of water ponds and seepage channels. The Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) has been processed to delineate the catchment morphometrical parameters (i.e. drainage networks, catchment divides and surface areas of different basins) and to examine the spatial distribution of cultivated fields and their relation to the extracted drainage networks. The soil of these closed drainage basins is mainly shallow and lithic with high calcium carbonate content; therefore, the downward percolation of excess irrigation water is limited by the development of subsurface hardpan, which also saturates the upper layer of soil with water. The subsurface seepage from the newly cultivated areas in the Farafra Oasis has revealed the pattern of buried alluvial channels, which are waterlogged and outlined by the growth of diagnostic saline shrubs. Furthermore, the courses of these waterlogged channels are coinciding with their counterparts of the SRTM DEM, and the recent satellite images show that the surface playas in the downstream of these channels are partially occupied by water ponds. On the other hand, a large water pond has occupied the main playa and submerged the surrounding fields, as a large area has been cultivated within a relatively small closed drainage basin in the Baharia Oasis. The geomorphology of closed drainage basins has to be considered when planning for a new cultivation in dryland catchments to better control waterlogging hazards. The "dry-drainage" concept can be implemented as the drainage and seepage water can be

  9. Geoarchaeological investigations at the Winger site: A Late Paleoindian bison bonebed in Southwestern Kansas, U.S.A

    USGS Publications Warehouse

    Mandel, R.D.; Hofman, J.L.

    2003-01-01

    The Winger site is a deeply buried Late Paleoindian bison bonebed in a playa basin on the High Plains of midcontinental North America. The site is one of few stratified, Late Paleoindian bison kills recorded in the region. The bonebed is exposed in the bank of an intermittent stream that cut into the edge of the playa basin. Avocational archaeologists excavated a small portion of the exposed bonebed in the early 1970s and reported flakes in association with the skeletal remains. Limited reinvestigations of the site were undertaken in 2001, and a monthlong excavation was conducted in 2002 to assess the stratigraphy, geochronology, and archaeology. The bonebed is 35 ni long in a buried soil developed in fine-grained basin fill overlain by early Holocene alluvium (arroyo fill). Recent alluvium overlies a soil developed in the early Holocene alluvium, and modern deposits of eolian sand 2 to to < 35 cm thick mantle the site area. Artifacts found at the site include two Allen points and a flake tool discovered in the bone bed, and a biface and Allen point fragment in disturbed bonebed deposits. Excavation of 9 m2 of the bone bed revealed some fully articulated skeletons, and taphonomic observations suggest some of the bison collapsed while standing in a playa or pond margin setting. The remains of at least six bison are represented in the excavated sample from 2002, but many more animals are represented in the bonebed. A 14C age of ca. 9000 yr B.P. was determined on collagen from bison rib fragments. This age is consistent with the diagnostic artifacts found at Winger. ?? 2003 Wiley Periodicals, Inc.

  10. Observations of Near-Surface Heat-Flux and Temperature Profiles Through the Early Evening Transition over Contrasting Surfaces

    NASA Astrophysics Data System (ADS)

    Jensen, Derek D.; Nadeau, Daniel F.; Hoch, Sebastian W.; Pardyjak, Eric R.

    2016-06-01

    Near-surface turbulence data from the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program are used to study countergradient heat fluxes through the early evening transition. Two sites, subjected to similar large-scale forcing, but with vastly different surface and sub-surface characteristics, are considered. The Playa site is situated at the interior of a large dry lakebed desert with high sub-surface soil moisture, shallow water table, and devoid of vegetation. The Sagebrush site is located in a desert steppe region with sparse vegetation and little soil moisture. Countergradient sensible heat fluxes are observed during the transition at both sites. The transition process is both site and height dependent. At the Sagebrush site, the countergradient flux at 5 m and below occurs when the sign change of the sensible heat flux precedes the local temperature gradient sign change. For 10 m and above, the countergradient flux occurs when the sign change of the sensible heat flux follows the local temperature gradient sign change. At the Playa site, the countergradient flux at all tower levels occurs when the sign change of the sensible heat flux follows the local temperature gradient sign change. The phenomenon is explained in terms of the mean temperature and heat-flux evolution. The temperature gradient sign reversal is a top-down process while the flux reversal occurs nearly simultaneously at all heights. The differing countergradient behaviour is primarily due to the different subsurface thermal characteristics at the two sites. The combined high volumetric heat capacity and high thermal conductivity at the Playa site lead to small vertical temperature gradients that affect the relative magnitude of terms in the heat-flux tendency equation. A critical ratio of the gradient production to buoyant production of sensible heat flux is suggested so as to predict the countergradient behaviour.

  11. Hydrological indications of aeolian salts in mid-latitude deserts of northwestern China

    NASA Astrophysics Data System (ADS)

    Zhu, Bing-Qi

    2016-06-01

    Large sandy deserts in middle latitude of northwestern China were studied on salt variations in modern and ancient aeolian sediments, aiming to explore their hydrological indications at the present and past. Globally, sulphate is rich in arid to semi-arid deserts, including the aeolian loess sediments in China and soils in low-latitude deserts, but is less common in the aeolian sediments from the mid-latitude deserts in this study. The compositional differences between aeolian salts and local natural waters is evident, indicating the chemistry of aeolian salts and the associated parent brines may be significantly different than that predicted for hydrologically closed systems. The formation of aeolian salts in the studied deserts is strongly controlled by earth surface processes in a large scale but not in a local scale. Vertical changes in facies and salinities are abrupt in the studied palaeo-aeolian sediment samples, which were interbedded by lacustrine/fluvial sediments with OSL and 14C ages ranging between 40 and 2 ka BP, reflecting rapid high-amplitude changes in hydrological settings during late Pleistocene to later Holocene in these ancient playa systems. A great difference in salt composition between aeolian and lacustrine sediments suggests that the inorganic salt is a latent geoproxy in revealing local hydrological variations and climate change in the desert areas. But the environmental indications could be amphibolous for the sedimentary sequences with dual/multiple depositional end-members; under this situation an increase in sequence salinity does not always represent an enhanced environmental aridity. Ancient playas are arid or humid at the same time based on several sporadic records is not a valid approach to correlation of salt deposits in adjacent saline playa basin in the studied areas. Effects of earth surface processes including erosion, deposition and other processes on sediment properties will bias the hydrological implications of sediment

  12. Paleoclimatic implications of fossil shoreline deposits in the southern basin and range province during the Pleistocene-Holocene transition

    NASA Astrophysics Data System (ADS)

    Kowler, A. L.

    2010-12-01

    Paleolake shoreline deposits throughout the southern Basin and Range (SBAR) signify past intervals of steady-state climatic conditions occuring during the late Pleistocene slightly before, as well as after the Last Glacial Maximum (LGM; ~23-19 Ka). Unfortunately, a lack of knowledge about the age of fossil shoreline deposits—due to C-14 related uncertainties and incomplete dating of shorelines—has resulted in a large gap in our knowledge about past climatic and surface hydrologic conditions in the SBAR. Several studies collectively reveal multiple lake level oscillations during the LGM and last part of the Pleistocene, with reasonably well dated shoreline deposits existing for only four paleolakes: one in central New Mexico (Estancia), two in southwestern New Mexico (Playas and Cloverdale), and one in southeastern Arizona (Cochise). In summary, there is evidence for a pre-LGM high-stand at Cochise (>26 Ka), LGM high-stands at Estancia and Cloverdale (>20-16 Ka), deglacial age high-stands at Playas and Cochise (16-13 Ka), and latest Pleistocene-early Holocene still stands of as yet undetermined elevation at Playas and Estancia (13-9K). Further, the absence of high-stands from 11-10 Ka suggests that the Younger Dryas climatic reversal—which is detected in the stable O isotopic composition of speleothems from Cave-of-the-Bells in southeastern Arizona—was marked there by a decrease in mean annual air temperature without a significant increase in precipitation. Alternatively, if a return to glacial precipitation levels did occur, then it was for an interval so short that sedimentological evidence was not preserved. This presentation will cover the afore mentioned chronologies, along with discussion about associated atmospheric circulation patterns in the SBAR and across western North America.

  13. Mapping bathymetry and rip channels with WorldView2 multispectral data

    NASA Astrophysics Data System (ADS)

    Trimble, S. M.; Houser, C.

    2014-12-01

    Rip currents are a worldwide coastal hazard that have claimed 616 lives in Costa Rica since 2001 (~50/yr). Lifeguard staff, warning signs, and flag systems have been shown to reduce deaths at rip-prone beaches but are not a perfect system. At Playa Cocles, a popular beach destination along the Caribbean Coast of Costa Rica near Puerto Viejo, lifeguards post flags at the mouth of the 3 to 6 rip currents present each morning. In July 2014, these dangerous currents were measured with floating GPS drogues at speeds up to 3.1 m/s. The purpose of this study is to demonstrate the capability of the Digital Globe WorldView2 (WV2) multispectral satellite for identifying rip channels and mapping bathymetry in the surf zone (20m and less), because rips form at topographically low spots in the bathymetry as a result of feedback amongst waves, substrate, and antecedent bathymetry. WV2 was launched in 2009; it has a 1.1 day pass-over rate with 1.84m ground pixel resolution of 8 bands, including 'yellow' (585-625 nm) and 'coastal blue' (400-450 nm). Using one 25km2 image from 23 December 2009, during the "high season" of tourism, a bathymetric map of Playa Cocles is created and measured for accuracy. Results of the study will assist the Comisión Nacional de Emergencias de Costa Rica and the town of Puerto Viejo by creating a rip current hazard evaluation and prediction system for the rip-prone beach of Playa Cocles. This creation methodology may be repeated for any following dates or other locations in Costa Rica (or anywhere on the globe captured by WV2). Future work will build on this research to determine rip current strength, location, and seasonality from a combination of WV2 satellite information and field data.

  14. Description of floodplains and wetlands, Deaf Smith County site, Texas

    SciTech Connect

    Not Available

    1986-11-01

    Floodplains and wetlands are important features of the Texas Panhandle landscape, and are found on the Deaf Smith County site and in its vicinity. Use or disturbance of floodplains and wetlands in relation to the Civilian Radioactive Waste Management Program is subject to environmental review requirements implementing two Executive Orders. This report provides general information on playa wetlands in the Texas Panhandle, and describes and maps floodplains and wetlands on the Deaf Smith site and in its vicinity. The report is based on the published literature, with information from limited field reconnaissance included.

  15. Recovery of the Space Shuttle Columbia Avionics

    NASA Technical Reports Server (NTRS)

    Hames, Kevin L.

    2003-01-01

    Lessons Learned: a) Avionics data can playa critical role in the investigation of a "close call" or accident. b) Avionics designers should think about the role their systems might play in an investigation. c) Know your data, down to the bit level. d) Know your spacecraft - follow the data. e) Internal placement of circuit cards can affect their survivability. f) Think about how to reconstruct nonvolatile memory (e.g. serialize IC's, etc.) g) Use of external assets can aid in extracting data from avionics.

  16. Tectonically induced climate and its control on the distribution of depositional systems in a continental foreland basin, Cloverly and Lakota Formations (Lower Cretaceous) of Wyoming, U.S.A.

    NASA Astrophysics Data System (ADS)

    Elliott, William S.; Suttner, Lee J.; Pratt, Lisa M.

    2007-12-01

    Continental sediments of the Cloverly and Lakota Formations (Lower Cretaceous) in Wyoming are subdivided into three depositional systems: perennial to intermittent alluvial, intermittent to ephemeral alluvial, and playa. Chert-bearing sandstones, conglomerates, carbonaceous mudrocks, blocky mudrocks, and skeletal limestones were deposited by perennial to intermittent alluvial systems. Carbonaceous mudrocks contain abundant wood fragments, cuticle and cortical debris, and other vascular plant remains representing deposition in oxbow lakes, abandoned channels, and on floodplains under humid to seasonal conditions. Intraformational conglomerates, sandstones, bioturbated and blocky mudrocks with caliche nodules, and bioturbated limestones characterize deposition in intermittent to ephemeral alluvial systems. Bioturbated limestones are encased in bioturbated mudrocks with abundant pseudo-slickensides. The presence of caliche nodules in some of the blocky to bioturbated mudrocks is consistent with supersaturation and precipitation of calcium carbonate from groundwater under semi-arid conditions. Caliche nodules, pseudo-slickensides, and carbonate-rich floodplain sediments are interpreted to have been deposited by intermittent to ephemeral alluvial systems under seasonal to semi-arid climatic conditions. Laminated mudrocks, siltstones, vuggy carbonates, bedded to nodular evaporites, pebbly mudrocks, and diamictites were deposited in evaporative alkaline lakes or playas. Pebbly mudrocks and diamictites are interpreted to represent deposition from channelized and unchannelized hyperconcentrated flows on a playa, resulting from intense rain events within the basin. The areal abundance and distribution of these depositional systems change systematically across the overfilled portion of the Early Cretaceous Cordilleran foreland basin in Wyoming. The lower part (A-interval) of the Cloverly and Lakota Formations is characterized by deposits of perennial to intermittent rivers

  17. [Osteoarticular paleopathology in a Chinchorro body: report of one case].

    PubMed

    Silva-Pinto, Verónica; Valenzuela, Daniela; Sepúlveda, Marcela

    2013-05-01

    We report a severe osteo-arthropathy in a body of a Chinchorro adult mole exhumed from the pre-Hispanic site of Playa Miller 8, located in the city of Arica, on the northern coast of Chile. The advanced state of joint disease shows that the individual was cared by his social group, to be able to survive. This care was perpetuated in the postmortem treatment, applying red color to the body. Particular self-care social dynamics of Chinchorro society are inferred.

  18. Online Resource for Earth-Observing Satellite Sensor Calibration

    NASA Technical Reports Server (NTRS)

    McCorkel, J.; Czapla-Myers, J.; Thome, K.; Wenny, B.

    2015-01-01

    The Radiometric Calibration Test Site (RadCaTS) at Railroad Valley Playa, Nevada is being developed by the University of Arizona to enable improved accuracy and consistency for airborne and satellite sensor calibration. Primary instrumentation at the site consists of ground-viewing radiometers, a sun photometer, and a meteorological station. Measurements made by these instruments are used to calculate surface reflectance, atmospheric properties and a prediction for top-of-atmosphere reflectance and radiance. This work will leverage research for RadCaTS, and describe the requirements for an online database, associated data formats and quality control, and processing levels.

  19. Ecological investigations at the Pantex Plant Site, 1992

    SciTech Connect

    Cushing, C.E.; Mazaika, R.R.; Phillips, R.C.

    1993-09-01

    In 1992, Pantex requested that Pacific Northwest Laboratory (PNL) conduct a series of ecological surveys to provide baseline information for designing detailed ecological studies on the various ecosystems present at the Pantex plant site near Amarillo, Texas. To this end, PNL scientist and technicians visited the site at different times to conduct investigations and collect samples: July 6--13: birds, small mammals, general habitat assessment; August 10--14: wetland vegetation, birds, small mammals, Playa invertebrates; and September 7--11: birds, small mammals. This report presents the results of these three surveys.

  20. Unmixing AVIRIS data to provide a method for vegetation fraction subtraction

    NASA Technical Reports Server (NTRS)

    Zamudio, J. A.

    1992-01-01

    Five flight lines of Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were acquired over the Dolly Varden Mountains in northeastern Nevada on 2 June 1989. Signal-to-noise ratio values are given. The empirical line method was used to convert AVIRIS radiance values to reflectance. This method involves calculating gain and offset values for each band. These values are based upon a comparison of the imaging spectrometer data and field reflectance measurements, both taken over the same ground targets. The targets used were a dark andesite flow and a bright playa.

  1. In situ spectroradiometric quantification of ERTS data

    NASA Technical Reports Server (NTRS)

    Yost, E.

    1973-01-01

    The task of correlating in situ spectral reflectance measurements with ERTS imagery has commenced. A method of additive color analysis of a single multispectral band taken on different dates indicates that ERTS-1 bulk images have sufficient spatial and spectral fidelity to show indications of the presence of soil moisture in desert playas and changes in soil moisture with time. The chain of causality between soil moisture, in situ spectral reflectance, and ERTS multispectral scanner image density remains to be established during the subsequent phases of this study.

  2. Sedimentology, geochemistry and rock magnetic properties of beach sands in Galapagos Islands - implications for nesting marine turtles

    NASA Astrophysics Data System (ADS)

    Perez-Cruz, L.; Urrutia-Fucugauchi, J.; Vazquez-Gutierrez, F.; Carranza-Edwards, A.

    2007-12-01

    Marine turtles are well known for their navigation ability in the open ocean and fidelity to nesting beaches. Green turtle adult females migrate from foraging areas to island nesting beaches, traveling hundreds or thousands of kilometers each way. The marine turtle breeding in the Galapagos Islands is the Green Sea Turtle (Chelonia mydas agassisi); fairly common throughout the islands but with nesting sites located at Las Bachas (Santa Cruz), Barahona and Quinta Playa (Isabela), Salinas (Baltra), Gardner Bay (Española) and Bartolomé Islet. In order to characterize and to identify the geochemical signature of nesting marine turtle beaches in Galapagos Islands, sedimentological, geochemical and rock magnetic parameters are used. A total of one hundred and twenty sand samples were collected in four beaches to relate compositional characteristics between equivalent areas, these are: Las Bachas, Salinas, Barahona and Quinta Playa. Grain size is evaluated using laser particle analysis (Model Coulter LS 230). Bulk ICP-MS geochemical analysis is performed, following trace elements are analyzed: Al, V, Cr, Co, Ni, Cu, Zn, Cd, Ba, Pb, Fe, Mn, K, Na, Mg, Sr, Ca and Hg; and low-field magnetic susceptibility is measured in all samples at low and high frequencies. Granulometric analysis showed that Barahona and Quinta Playa are characterized for fine grained sands. In contrast, Salinas and Las Bachas exhibit medium to coarse sands. Trace metals concentrations and magnetic susceptibility show different distribution patterns in the beach sands. Calcium is the most abundant element in the samples. In particular, Co, K, and Na show similar concentrations in the four beaches. Las Bachas beach shows highest concentrations of Pb and Hg (maximum values 101.1 and 118.5 mg/kg, respectively), we suggest that the enrichment corresponds to an anthropogenic signal. Salinas beach samples show high concentrations of Fe, V, Cr, Zn, Mn and the highest values of magnetic susceptibility (maximum

  3. Spectral and Geological Characterization of Beach Components in Northern Puerto Rico

    NASA Astrophysics Data System (ADS)

    Caraballo Álvarez, I. O.; Torres-Perez, J. L.; Barreto, M.

    2015-12-01

    Understanding how changes in beach components may reflect beach processes is essential since variations along beach profiles can shed light on river and ocean processes influencing beach sedimentation and beachrock formation. It is likely these influences are related to beach proximity within the Río Grande de Manatí river mouth. Therefore, this study focuses on characterizing beach components at two sites in Manatí, Puerto Rico. Playa Machuca and Playa Tombolo, which are separated by eolianites, differ greatly in sediment size, mineralogy, and beachrock morphology. Several approaches were taken to geologically and spectrally characterize main beach components at each site. These approaches included field and microscopic laboratory identification, granulometry, and a comparison between remote sensing reflectance (Rrs) obtained with a field spectroradiometer and pre-existing spectral library signatures. Preliminary results indicate a positive correlation between each method. This study may help explore the possibility of using only Rrs to characterize beach and shallow submarine components for detailed image analysis and management of coastal features.This study focuses on characterizing beach components at two sites in Manatí, Puerto Rico. Playa Machuca and Playa Tombolo, two beaches that are separated by eolianites, differ greatly in sediment size and mineralogy, as well as in beachrock morphology. Understanding how changes in beach components may reflect beach processes is essential, since it is likely that differences are mostly related to each beaches' proximity to the Río Grande de Manatí river mouth. Hence, changes in components along beach profiles can shed light on the river's and the ocean's influence on beach sedimentation and beachrock formation. Several approaches were taken to properly geologically and spectrally characterize the main beach components at each site. These approaches included field and microscopic laboratory identification

  4. Mars Exploration Rover Field Observations of Impact Craters at Gusev Crater and Meridiani Planum and Implications for Climate Change

    NASA Technical Reports Server (NTRS)

    Golombek, M.; Grant, J. A.; Crumpler, L. S.

    2005-01-01

    The Mars Exploration Rovers have provided a field geologist's perspective of impact craters in various states of degradation along their traverses at Gusev crater and Meridiani Planum. This abstract will describe the craters observed and changes to the craters that constrain the erosion rates and the climate [l]. Changes to craters on the plains of Gusev argue for a dry and desiccating environment since the Late Hesperian in contrast to the wet and likely warm environment in the Late Noachian at Meridiani in which the sulfate evaporites were deposited in salt-water playas or sabkhas.

  5. Relationships between topographic roughness and aeolian processes

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Lancaster, N.; Gaddis, L.; Rasmussen, K. R.; White, B. R.; Saunders, R. S.; Wall, S.; Dobrovolskis, Anthony R.; Iversen, J. D.

    1991-01-01

    The interaction between winds and desert surfaces has important implications for sediment transport on Earth, Mars, and Venus, and for understanding the relationships between radar backscatter and aerodynamic roughness as part of the NASA Shuttle Imaging radar (SIR-C) Mission. Here, researchers report results from measurements of boundary layer wind profiles and surface roughness at sites in Death Valley and discuss their implications. The sites included a flat to undulating gravel and sand reg, alluvial fans, and a playa. Estimates of average particle size composition of Death Valley sites and arithmetic mean values of aerodynamic roughness are given in tabular form.

  6. Directional variations in thermal emission from geologic surfaces

    NASA Technical Reports Server (NTRS)

    Jakosky, Bruce M.; Finiol, Gary W.; Henderson, Bradley G.

    1990-01-01

    The directional emission properties of geologic surfaces were investigated using a ground-based, hand-held infrared radiometer and thermistor probe. Field sites involved surfaces ranging from smooth playa and sand surfaces to a very rough aa lava flow. Large directional variations in thermal emission were found; they result from the presence of surface roughness at large scales producing spatial variations in kinetic temperature and at small scales producing emissivity variations. These variations are important in remotely determining surface structure and understanding surface energy balance and emission spectra.

  7. Desert Landforms and Surface Processes in the Mojave National Preserve and Vicinity

    USGS Publications Warehouse

    Stoffer, Philip W.

    2004-01-01

    Landscape features in the Mojave National Preserve are a product of ongoing processes involving tectonic forces, weathering, and erosion. Long-term climatic cycles (wet and dry periods) have left a decipherable record preserved as landform features and sedimentary deposits. This website provides and introduction to climate-driven desert processes influencing landscape features including stream channels, alluvial fans, playas (dry lakebeds), dunes, and mountain landscapes. Bedrock characteristics, and the geometry of past and ongoing faulting, fracturing, volcanism, and landscape uplift and subsidence influence the character of processes happening at the surface.

  8. Artificial-recharge experiments and operations on the Southern High Plains of Texas and New Mexico

    USGS Publications Warehouse

    Brown, Richmond F.; Signor, Donald C.

    1973-01-01

    Experiments using highly turbid water from playa lakes for injection into the Ogallala Formation have resulted in greatly decreased yield of the recharge wells, Recharge of ground or surface water of good quality has indicated, however, that injection through wells is an effective method of recharging the aquifer. Water that is slightly turbid can be successfully injected for a period of time, but generally results in constantly declining yields and capacity for recharge. Redevelopment through pumping and surging significantly prolongs the life of recharge wells under some conditions. Surface spreading is little practiced on the High Plains, but locally may be a feasible means of artificial recharge.

  9. Medium-term shoreline evolution of the mediterranean coast of Andalusia (SW Spain)

    NASA Astrophysics Data System (ADS)

    Liguori, Vincenzo; Manno, Giorgio; Messina, Enrica; Anfuso, Giorgio; Suffo, Miguel

    2015-04-01

    Coastal environment is a dynamic system in which numerous natural processes are continuously actuating and interacting among them. As a result, geomorphologic, physical and biological characteristics of coastal environments are constantly changing. Such dynamic balance is nowadays seriously threatened by the strong and increasing anthropic pressure that favors erosion processes, and the associated loss of environmental, ecologic and economic aspects. Sandy beaches are the most vulnerable environments in coastal areas. The aim of this work was to reconstruct the historical evolution of the Mediterranean coastline of Andalusia, Spain. The investigated area is about 500 km in length and includes the provinces of Cadiz, Malaga, Granada and Almeria. It is essentially composed by cliffed sectors with sand and gravel pocket beaches constituting independent morphological cells of different dimensions. This study was based on the analysis of aerial photos and satellite images covering a period of 55 years, between 1956 and 2011. Aerial photos were scanned and geo-referenced in order to solve scale and distortion problems. The shoreline was considered and mapped through the identification of the wet / dry sand limit which coincides with the line of maximum run-up; this indicator - representing the shoreline at the moment of the photo - is the most easily identifiable and representative one in microtidal coastal environments. Since shoreline position is linked to beach profile characteristics and to waves, tide and wind conditions at the moment of the photo, such parameters were taken into account in the calculation of shoreline position and changes. Specifically, retreat/accretion changes were reconstructed applying the DSAS method (Digital Shoreline Analysis System) proposed by the US Geological Survey. Significant beach accretion was observed at Playa La Mamola (Granada), with +1 m/y, because the construction of five breakwaters, and at Playa El Cantal (Almeria) and close

  10. Oil contamination of sedimentary shores of the Galápagos Islands following the wreck of the Jessica.

    PubMed

    Kingston, P F; Runciman, D; McDougall, J

    2003-01-01

    Sediment samples were collected from sandy beaches at a variety of sites in the southern Galápagos Archipelago to assess levels of hydrocarbon contamination following the wreck of the oil tanker Jessica. Hydrocarbon levels in sediments were generally very low by international standards ranging between 0.4 and 48.9 ppm, with contamination attributable to the Jessica only detected at three sites Santa Fe, Playa Estación (Puerto Ayora, Santa Cruz) and Long Beach (Isabela). There was evidence of residual hydrocarbon contamination from sources other than the wreck of the Jessica.

  11. The Triassic Santa Juana Formation at the lower Biobío River, south central Chile

    NASA Astrophysics Data System (ADS)

    Nielsen, Sven N.

    2005-09-01

    A sequence of Triassic rocks is exposed near the town of Concepción, Chile. These clastic strata are interpreted as the deposits of rivers, lakes, playas, and alluvial fans. The deposits comprise conglomerates, arkosic sandstones, and sand-, silt- and mudstones. Four facies associations comprising eight sedimentary facies can be distinguished. Plant fossils from the sedimentary sequence of the Santa Juana Formation indicate a Carnian age. The flora includes ferns ( Gleichenites, Cladophlebis, Dictyophyllum, Thaumatopteris, Asterotheca, Saportaea) and seed ferns ( Kurtziana, Antevsia, Dicroidium), ginkgophytes ( Sphenobaiera), cycads ( Pseudoctenis), conifers ( Heidiphyllum, Telemachus, Rissikia), and gymnosperms of uncertain affinities ( Linguifolium, Gontriglossa). Two new species are presented: Pseudoctenis santajuanensis and Gontriglossa reinerae.

  12. Ground water discharge by evapotranspiration in wetlands of an arid intermountain basin

    NASA Astrophysics Data System (ADS)

    Sanderson, John S.; Cooper, David J.

    2008-04-01

    SummaryTo improve basin-scale modeling of ground water discharge by evapotranspiration (ET) in relation to water table depth, daily ET was measured using the Bowen ratio energy balance method during 1999-2005 in five herbaceous plant dominated wetlands in an arid intermountain basin in Colorado, USA. Three wetlands were wet meadows supplied primarily by regional ground water flow and two were playas supplied primarily by local stream flow. In wet meadows, mean daily water table depth (WTD) ranged from 0.00 m (ground surface) to 1.2 m, with low inter-annual variability. In wet meadows, annual actual ET (ET a) was 751-994 mm, and ground water discharge from the shallow aquifer (ET g) was 75-88% of ET a. In playas, mean daily WTD ranged from -0.65 to 1.89 m, with high inter-annual variability. In playas, annual ET a was 352-892 mm, and ET g was 0-77% of ET a. The relationship of annual ET g to WTD was compared to existing ET g-WTD models. For wet meadows, ET g decreased exponentially as WTD increased from 0.13 to 0.95 m ( r2 = 0.83, CV = 5%, p < 0.001). In comparison with our findings, existing models under- and over-estimate ET g by -30% to 47% at WTD of 0.13 m, and they under-estimate ET g by -12% to -42% at WTD of 0.95 m. This study found that as the water table declined from near the soil surface to 0.95 m, ET g decreased only ˜26% versus 39-55% estimated by existing models. The magnitude of ET g decrease was 220 mm, whereas existing models predicted decreases up to 700 mm (218% greater). In playas, there was no clear ET g-WTD relationship. Instead, ET g was strongly dependent on the surface water supply. When sufficient surface water inputs occurred to meet ET demand, ET g was ≈0 mm/yr and independent of WTD. When inputs did not meet ET demand, ET g was positive though highly variable at WTD up to 1.68 m.

  13. 11. Photocopy of drawing (this photograph is an 8''x 10''contact ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Photocopy of drawing (this photograph is an 8''x 10''contact print; February 7, 1989 revision of a September, 1986 as built drawing by D. Monclova, in possession of the Highway Administration Office of the Puerto Rico Highway and Transportation Authority) Bridge over Santiago (sic) Channel, Route no. 2 km. 75.50, Arecibo, P.R. Bridge no. 53. No. 1 of 2. - Puente del Caño Carate, Spanning Cano Carate Channel, Arecibo, Arecibo Municipio, PR

  14. 13. Photocopy of drawing (this photograph is an 8''x 10'' ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. Photocopy of drawing (this photograph is an 8''x 10'' contact print; November 1, 1993 revision of a May, 1982 as built drawing by M. Villafane, in possession of the Highway System Administration Office of the Puerto Rico Highway and Transportation Authority) Bridge over Perdomo Channel, Road no. P.R.2, Km. 75.60, Arecibo, P.R. no. 1 of 3. - Puente del Caño Perdomo, Route PR-2 spanning Cano Perdomo Channel, Arecibo, Arecibo Municipio, PR

  15. 14. Photocopy of drawing (this photograph is an 8''x 10'' ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Photocopy of drawing (this photograph is an 8''x 10'' contact print; November 1, 1993 revision of a May, 1982 as built drawing by M. Villafane, in possession of the Highway System Administration Office of the Puerto Rico Highway and Transportation Authority) Bridge over Perdomo Channel, Road no. P.R.2, Km. 75.60, Arecibo, P.R. no. 2 of 3. - Puente del Caño Perdomo, Route PR-2 spanning Cano Perdomo Channel, Arecibo, Arecibo Municipio, PR

  16. 15. Photocopy of drawing (this photograph is an 8''x 10'' ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. Photocopy of drawing (this photograph is an 8''x 10'' contact print; November 1, 1993 revision of a May, 1982 as built drawing by M. Villafane, in possession of the Highway System Administration Office of the Puerto Rico Highway and Transportation Authority) Bridge over Perdomo Channel, Road no. P.R.2, Km. 75.60, Arecibo, P.R. no. 3 of 3. - Puente del Caño Perdomo, Route PR-2 spanning Cano Perdomo Channel, Arecibo, Arecibo Municipio, PR

  17. [Infant mortality in the indigenous population: backwardness and contrasts].

    PubMed

    Fernandez Ham, P

    1993-01-01

    Some 6.4 million speakers of indigenous languages were enumerated in the 1990 Mexican census. The same census provided the basis for an indirect estimate of infant mortality using data on the numbers of live born and surviving children. Municipios with 40% or more of the population speaking an indigenous language were studied. The overall estimated infant mortality rate for indigenous municipios was 55.1/1000 live births, the equivalent of the Mexican infant mortality rate around 1982. Mexico's national infant mortality rate in 1990 was 34.8/1000. Great contrasts were found in indigenous infant mortality rates. Campeche, Quintana Roo, and Yucatan, the states of the Mayan region, had a low rate of 35.09/1000, very close to the national average. Infant mortality levels were relatively low in the indigenous populations of Hidalgo, the state of Mexico, and Michoacan, with rates of 44 to 48. Chiapas, Oaxaca, Puebla, Durango, Guerrero, and San Luis Potosi had rates of 55 to 65. The highest rates were in states with few indigenous municipios, including Chihuahua, Jalisco, and Nayarit. The Huichol of Jalisco had the highest rate at 100.01/1000. Infant mortality levels were found to be correlated in different degrees with socioeconomic indicators. The highest infant mortality rates were in the indigenous regions with the poorest socioeconomic conditions.

  18. Swords into plowshares: Military geology and national security projects

    SciTech Connect

    Neal, J.T.

    1994-12-31

    Military geology and national security projects are often comparable, achieving their rai-son d`etre in support of national goals, military operations, and/or systems-all for vital national interests. The application of Geoscience to these ends, especially engineering geology, has occurred from pole to pole and included every conceivable environment and natural condition. In the conduct of such projects, the Geosciences have advanced, and vice versa. Desert trafficability, most notably regarding playa surfaces, is both temporary and variable and not a persistent condition as some early authors believed. Playas in Australia, Iran, and the US show that saline efflorescence is removed following surface water dissolution and subsequent deflation, resulting in very hard crusts. Magadiite, a hydrous sodium silicate and possible precursor of bedded chert, was first discovered in North America at Alkali Lake, OR, during a military project. Pleistocene Lake Trinity, a small and mostly buried evaporate basin in the northern Jornada del Muerto, NM, was discovered during exploratory drilling in support of a military test program.

  19. Geoarchaeology and Geochronology of the Miami (Clovis) Site, Southern High Plains of Texas

    NASA Astrophysics Data System (ADS)

    Holliday, Vance T.; Haynes, C. Vance; Hofman, Jack L.; Meltzer, David J.

    1994-03-01

    The Miami site, excavated in 1937, is in a small "playa" basin on the High Plains surface. The site is one of the earliest documented co-occurrences of Clovis points and mammoth. Reinvestigation of the site and related collections was undertaken to better understand the stratigraphy, geochronology, and archaeology. The basin, 23 m diameter × 1.6 m deep, filled with (1) dark gray silty clay, and (2) near the top of the section, a lens of well-sorted silt or loess. The basin started to fill ca. 13,700 yr B.P., the loess dates to ca. 11,400 yr B.P., and the bone bed probably dates to ca. 11,400-10,500 yr B.P. The loess may be the local manifestation of a "Clovis drought." The partial remains of five mammoths (three adults and two juveniles) were recovered in 1937; no other animal remains are known. The bone is heavily weathered and there are no clear indications of human modification. Artifacts found at the site include three Clovis points and a scraper found among the bones and two flakes and a scraper found on the surface near the playa. The origins of the bone and stone assemblage are uncertain but four scenarios are offered: a successful mammoth kill, an unsuccessful kill with wounded animals dying at the watering hole, opportunistic scavenging following natural deaths, or a palimpsest of multiple deaths following both natural and human causes.

  20. Assessment and Determination land uses of Qom's Hoze Soltan Lake southern lands by FAO Agenda and It's Rehabilitation Strategies

    NASA Astrophysics Data System (ADS)

    Karimpour Reihan, Majid

    2010-05-01

    Increase of playas, decrease of water quality, soil and plant degradation is one of important problems in recent decays. Notwithstanding increase of playa wetlands- 4 million ha in our country- is perform some investigations about this biome and components and this lack of investigation is made degradation of water, soil, plant potentials and at least desertification. Then, management the biome and planning for sustainable development is very important because of sensitive this environments and has requirement to recognize ecological properties and components, so in this study, try to investigate fasting and latent this regions. At last for potentialization of region for rangeland, water and dry culture use, assessment and classification of region was performed with aim of FAO formula. According to this formula, environmental factors studied and performed grading and classifying. Basis on results, the region is not proper for dry farming and view of water farming and rangeland was settled in 5 and 6 classes. Latest result should be conserving the region. For this act, our introduced 13 halophyte plats with view of investigation of 20 factors. May god will, ganged this regions to good rangelands and forests of dry regions. Key words: Assessment of lands, Hoze Soltane of Qom, environmental factors, FAO, Compatible Plants, Reclamation strategies

  1. Global analysis of the effect of local climate on the hatchling output of leatherback turtles

    PubMed Central

    Santidrián Tomillo, Pilar; Saba, Vincent S.; Lombard, Claudia D.; Valiulis, Jennifer M.; Robinson, Nathan J.; Paladino, Frank V.; Spotila, James R.; Fernández, Carlos; Rivas, Marga L.; Tucek, Jenny; Nel, Ronel; Oro, Daniel

    2015-01-01

    The most recent climate change projections show a global increase in temperatures along with precipitation changes throughout the 21st century. However, regional projections do not always match global projections and species with global distributions may exhibit varying regional susceptibility to climate change. Here we show the effect of local climatic conditions on the hatchling output of leatherback turtles (Dermochelys coriacea) at four nesting sites encompassing the Pacific, Atlantic and Indian Oceans. We found a heterogeneous effect of climate. Hatchling output increased with long-term precipitation in areas with dry climatic conditions (Playa Grande, Pacific Ocean and Sandy Point, Caribbean Sea), but the effect varied in areas where precipitation was high (Pacuare, Caribbean Sea) and was not detected at the temperate site (Maputaland, Indian Ocean). High air temperature reduced hatchling output only at the area experiencing seasonal droughts (Playa Grande). Climatic projections showed a drastic increase in air temperature and a mild decrease in precipitation at all sites by 2100. The most unfavorable conditions were projected for Sandy Point where hatching success has already declined over time along with precipitation levels. The heterogeneous effect of climate may lead to local extinctions of leatherback turtles in some areas but survival in others by 2100. PMID:26572897

  2. Shell shape variation in the Nassariid Buccinanops globulosus in northern Patagonia

    NASA Astrophysics Data System (ADS)

    Avaca, María Soledad; Narvarte, Maite; Martín, Pablo; van der Molen, Silvina

    2013-09-01

    Morphological variation among natural populations is a phenomenon commonly observed in marine invertebrates and well studied, particularly, in shelled gastropods. The nassariid Buccinanops globulosus is interesting to study shell shape variation because it exhibits strong interpopulation differences in life history features, including maximum size, fecundity and growth rate. In this study, we examined the pattern of variation in size and shell shape among populations and between sexes of B. globulosus (Bahía San Antonio 40°29'S 63°01'W, Playa Villarino 40°45'S 64°40'W and Bahía Nueva 42°46'S 65°02'W). In particular, we used geometric morphometric techniques to test: (1) whether the two components of shell morphology (size and shape) are independent and (2) whether shape differences between sexes are consistently found among populations, regardless of their body sizes. Our results show shell shape variation between the populations of B. globulosus of northern Patagonia. Intra-specific shell shape variation is affected by body size, indicating allometry. Regardless of the size differences, individuals from Playa Villarino have high-spired shells, and shorter apertures and wider columellar area than individuals from the other populations. Also, sex-related shape differences were consistently found at each population, thus suggesting a common sexual dimorphism in shell morphology for this species. The functional significance of the variability found is discussed in terms of the flexibility of developmental programmes for morphology as well as the evolution of phenotypic plasticity.

  3. Global analysis of the effect of local climate on the hatchling output of leatherback turtles.

    PubMed

    Santidrián Tomillo, Pilar; Saba, Vincent S; Lombard, Claudia D; Valiulis, Jennifer M; Robinson, Nathan J; Paladino, Frank V; Spotila, James R; Fernández, Carlos; Rivas, Marga L; Tucek, Jenny; Nel, Ronel; Oro, Daniel

    2015-01-01

    The most recent climate change projections show a global increase in temperatures along with precipitation changes throughout the 21(st) century. However, regional projections do not always match global projections and species with global distributions may exhibit varying regional susceptibility to climate change. Here we show the effect of local climatic conditions on the hatchling output of leatherback turtles (Dermochelys coriacea) at four nesting sites encompassing the Pacific, Atlantic and Indian Oceans. We found a heterogeneous effect of climate. Hatchling output increased with long-term precipitation in areas with dry climatic conditions (Playa Grande, Pacific Ocean and Sandy Point, Caribbean Sea), but the effect varied in areas where precipitation was high (Pacuare, Caribbean Sea) and was not detected at the temperate site (Maputaland, Indian Ocean). High air temperature reduced hatchling output only at the area experiencing seasonal droughts (Playa Grande). Climatic projections showed a drastic increase in air temperature and a mild decrease in precipitation at all sites by 2100. The most unfavorable conditions were projected for Sandy Point where hatching success has already declined over time along with precipitation levels. The heterogeneous effect of climate may lead to local extinctions of leatherback turtles in some areas but survival in others by 2100. PMID:26572897

  4. Classification of the LCVF AVIRIS test site with a Kohonen artificial neural network

    NASA Technical Reports Server (NTRS)

    Merenyi, Erzsebet; Singer, Robert B.; Farrand, William H.

    1993-01-01

    We present a classification of an AVIRIS spectral image of the Lunar Crater Volcanic Field (LCVF). Geologic mapping from such data is made possible by distinctive mineral signatures: absorption features and the shape of the spectral continuum. The subtle spectral shape differences between some of the geological units in this scene along with the high dimensionality of the spectral presents a challenging pattern recognition task. We found an artificial neural network powerful in separating 13 geological units based on the full spectral resolution. The LCVF, in northern Nye County, Nevada, was the primary focus of the NASA-sponsored Geologic Remote Sensing Field Experiment in the summer of 1989. It consists of over 100 square miles of Quaternary basaltic pyroclastic and flow deposits. These deposits lie atop ignimbrites and silicic lava flows of Tertiary age and in turn are overlain by Quaternary alluvial and playa deposits. This AVIRIS image was collected on September 29, 1989 at 11:44 at 11:44 PDT. The 256-by-256 pixel subsection in this study contains oxidized basaltic cinder deposits, the southern half of the Lunar Lake playa, and outcrops of the Rhyollite of Big Sand Spring Valley. Vegetation in LCVF is sparse, but locally abundant within washes and near springs.

  5. Geochemistry of Precambrian carbonates: 3-shelf seas and non-marine environments of the Archean

    SciTech Connect

    Veizer, J. Ruhr Universitaet, Bochum ); Clayton, R.N. ); Hinton, R.W. Grant Institute of Geology, Edinburgh ); von Brunn, V. ); Mason, T.R. ); Buck, S.G. ); Hoefs, J. )

    1990-10-01

    A comprehensive whole-rock study of mineralogical, chemical, and isotopic attributes of Archean carbonates suggests that their lithologies and facies have been controlled by tectonic setting. In the first two papers of this series they have shown that the dominant lithology of sedimentary carbonates in greenstone belt settings is limestone. In this paper the authors suggest that the Archean shelf sequences are mostly dolostone, and the contemporaneous lacustrine playa lakes are characterized by limestone facies. The present study is of the shelf environments of the Archean, represented by the Pongola Supergroup of South Africa and the Hamersley Group of Australia. The lacustrine playa examples have been sampled from the Ventersdorp Supergroup of South Africa and the Fortescue Group of Australia. Geological, trace element, and oxygen isotope considerations of the shelf carbonates suggest that their original mineralogy may have been aragonite and that the Pongola dolostones probably represent a direct dolomitization product of this precursor. In contrast, the stabilization of the Hamersley carbonates may have involved an additional step of transformation of a metastable precursor into limestone prior to dolomitization.

  6. Remotely-Sensed Regional-Scale Evapotranspiration of a Semi-Arid Great Basin Desert and its Relationship to Geomorphology, Soils, and Vegetation

    NASA Technical Reports Server (NTRS)

    Laymon, C.; Quattrochi, D.; Malek, E.; Hipps, L.; Boettinger, J.; McCurdy, G.

    1997-01-01

    Landsat Thematic Mapper data is used to estimate instantaneous regional-scale surface water and energy fluxes in a semi-arid Great Basin desert of the western United States. Results suggest that it is possible to scale from point measurements of environmental state variables to regional estimates of water and energy exchange. This research characterizes the unifying thread in the classical climate-topography-soil-vegetation relation-the surface water and energy balance-through maps of the partitioning of energy throughout the landscape. The study was conducted in Goshute Valley of northeastern Nevada, which is characteristic of most faulted graben valleys of the Basin and Range Province of the western United States. The valley comprises a central playa and lake plain bordered by alluvial fans emanating from the surrounding mountains. The distribution of evapotranspiration (ET) is lowest in the middle reaches of the fans where the water table is deep and plants are small, resulting in low evaporation and transpiration. Highest ET occurs in the center of the valley, particularly in the playa, where limited to no vegetation occurs, but evaporation is relatively high because of a shallow water table and silty clay soil capable of large capillary movement. Intermediate values of ET are associated with large shrubs and is dominated by transpiration.

  7. Remotely-Sensed Regional-Scale Evapotranspiration of a Semi-Arid Great Basin Desert and its Relationship to Geomorphology, Soils, and Vegetation

    NASA Technical Reports Server (NTRS)

    Laymon, C.; Quattrochi, D.; Malek, E.; Hipps, L.; Boettinger, J.; McCurdy, G.

    1998-01-01

    Landsat thematic mapper data are used to estimate instantaneous regional-scale surface water and energy fluxes in a semi-arid Great Basin desert of the western United States. Results suggest that it is possible to scale from point measurements of environmental state variables to regional estimates of water and energy exchange. This research characterizes the unifying thread in the classical climate-topography-soil-vegetation relation -the surface water and energy balance-through maps of the partitioning of energy throughout the landscape. The study was conducted in Goshute Valley of northeastern Nevada, which is characteristic of most faulted graben valleys of the Basin and Range Province of the western United States. The valley comprises a central playa and lake plain bordered by alluvial fans emanating from the surrounding mountains. The distribution of evapotranspiration (ET) is lowest in the middle reaches of the fans where the water table is deep and plants are small, resulting in low evaporation and transpiration. Highest ET occurs in the center of the valley, particularly in the playa, where limited to no vegetation occurs, but evaporation is relatively high because of a shallow water table and silty clay soil capable of large capillary movement. Intermediate values of ET are associated with large shrubs and is dominated by transpiration.

  8. Three-dimensional geologic mapping of the Cenozoic basin fill, Amargosa Desert basin, Nevada and California

    USGS Publications Warehouse

    Taylor, Emily M.; Sweetkind, Donald S.

    2014-01-01

    Understanding the subsurface geologic framework of the Cenozoic basin fill that underlies the Amargosa Desert in southern Nevada and southeastern California has been improved by using borehole data to construct three-dimensional lithologic and interpreted facies models. Lithologic data from 210 boreholes from a 20-kilometer (km) by 90-km area were reduced to a limited suite of descriptors based on geologic knowledge of the basin and distributed in three-dimensional space using interpolation methods. The resulting lithologic model of the Amargosa Desert basin portrays a complex system of interfingered coarse- to fine-grained alluvium, playa and palustrine deposits, eolian sands, and interbedded volcanic units. Lithologic units could not be represented in the model as a stacked stratigraphic sequence due to the complex interfingering of lithologic units and the absence of available time-stratigraphic markers. Instead, lithologic units were grouped into interpreted genetic classes, such as playa or alluvial fan, to create a three-dimensional model of the interpreted facies data. Three-dimensional facies models computed from these data portray the alluvial infilling of a tectonically formed basin with intermittent internal drainage and localized regional groundwater discharge. The lithologic and interpreted facies models compare favorably to resistivity, aeromagnetic, and geologic map data, lending confidence to the interpretation.

  9. Mars' "White Rock" feature lacks evidence of an aqueous origin: Results from Mars Global Surveyor

    USGS Publications Warehouse

    Ruff, S.W.; Christensen, P.R.; Clark, R.N.; Kieffer, H.H.; Malin, M.C.; Bandfield, J.L.; Jakosky, B.M.; Lane, M.D.; Mellon, M.T.; Presley, M.A.

    2001-01-01

    The "White Rock" feature on Mars has long been viewed as a type example for a Martian playa largely because of its apparent high albedo along with its location in a topographic basin (a crater). Data from the Mars Global Surveyor Thermal Emission Spectrometer (TES) demonstrate that White Rock is not anomalously bright relative to other Martian bright regions, reducing the significance of its albedo and weakening the analogy to terrestrial playas. Its thermal inertia value indicates that it is not mantled by a layer of loose dust, nor is it bedrock. The thermal infrared spectrum of White Rock shows no obvious features of carbonates or sulfates and is, in fact, spectrally flat. Images from the Mars Orbiter Camera show that the White Rock massifs are consolidated enough to retain slopes and allow the passage of saltating grains over their surfaces. Material appears to be shed from the massifs and is concentrated at the crests of nearby bedforms. One explanation for these observations is that White Rock is an eroded accumulation of compacted or weakly cemented aeolian sediment. Copyright 2001 by the American Geophysical Union.

  10. Landsat radiometric continuity using airborne imaging spectrometry

    NASA Astrophysics Data System (ADS)

    McCorkel, J.; Angal, A.; Thome, K.; Cook, B.

    2015-12-01

    NASA Goddard's Lidar, Hyperspectral and Thermal Imager (G-LiHT) includes a scanning lidar, an imaging spectrometer and a thermal camera. The Visible Near-Infrared (VNIR) Imaging Spectrometer acquires high resolution spectral measurements (1.5 nm resolution) from 0.4 to 1.0 µm. The SIRCUS-based calibration facility at NASA's Goddard Space Flight Center was used to measure the absolute spectral response (ASR) of the G-LiHT's imaging spectrometer. Continuously tunable lasers coupled to an integrating sphere facilitated a radiance-based calibration for the detectors in the reflective solar bands. The transfer of the SIRCUS-based laboratory calibration of G-LiHT's Imaging Spectrometer to the Landsat sensors (Landsat 7 ETM+ and Landsat 8 OLI) is demonstrated using simultaneous overpasses over the Red Lake Playa and McClaw's Playa sites during the commissioning phase of Landsat 8 in March 2013. Solar Lunar Absolute Imaging Spectrometer (SOLARIS) is the calibration demonstration system for the reflected solar instrument of CLARREO. A portable version of SOLARIS, known as Suitcase SOLARIS, also calibrated using a SIRCUS-based setup, was deployed for ground measurements as a part of both the field campaigns. Simultaneous measurements of SOLARIS allow cross-comparison with G-LiHT and Landsat sensors. The transfer of the lab-based calibration of G-LiHT to Landsat sensors show that the sensors agree within 5% with a 1-3% calibration uncertainty of G-LiHT's Imaging Spectrometer.

  11. Radiometric calibration of Advanced Land Imager using reflectance-based results between 2001 and 2005

    NASA Astrophysics Data System (ADS)

    McCorkel, J.; Thome, K.; Biggar, S.; Kuester, M.

    2006-08-01

    The Landsat series of sensors have supplied the remote sensing community with a continuous data set dating to the early 1970s. An important aspect of retaining the continuity of these data is that a Landsat follow-on as well as current Landsat instruments must be understood radiometrically throughout their mission. The Advanced Land Imager (ALI), for example, was developed as a prototype for the next generation of Landsat Instruments, and as such there was a significant effort to understand its radiometric characteristics as well as how it compares with previous Landsat sensors. The Remote Sensing Group at the University of Arizona has been part of this effort since the late 2000 launch of ALI through the use of the reflectance-based method of vicarious calibration. The reflectance-based approach consists of ground-based measurements of atmospheric conditions and surface reflectance at the time of satellite overpass to predict the at-sensor radiance seen by the sensor under study. The work compares results from the reflectance-based approach obtained from well-characterized test sites such as Railroad Valley Playa in Nevada and Ivanpah Playa in California as applied to ALI, Landsat-5 TM, and Landsat-7 EMT+. The results from the comparison use a total of 14 ALI dates spanning in time from 2001 to late 2005 and show that ALI agrees with the current radiometric results from TM and ETM+ to within 5%.

  12. On the dispersal of leatherback turtle hatchlings from Mesoamerican nesting beaches.

    PubMed

    Shillinger, George L; Di Lorenzo, Emanuele; Luo, Hao; Bograd, Steven J; Hazen, Elliott L; Bailey, Helen; Spotila, James R

    2012-06-22

    So little is known about the early life history of leatherback turtles (Dermochelys coriacea) from hatchling to adulthood that this period has been termed the 'lost years'. For critically endangered eastern Pacific leatherback populations, continued and rapid declines underscore the urgent need to develop conservation strategies across all life stages. We investigate leatherback hatchling dispersal from four Mesoamerican nesting beaches using passive tracer experiments within a regional ocean modelling system. The evolution of tracer distribution from each of the nesting beaches showed the strong influence of eddy transport and coastal currents. Modelled hatchlings from Playa Grande, Costa Rica, were most likely to be entrained and transported offshore by large-scale eddies coincident with the peak leatherback nesting and hatchling emergence period. These eddies potentially serve as 'hatchling highways', providing a means of rapid offshore transport away from predation and a productive refuge within which newly hatched turtles can develop. We hypothesize that the most important leatherback nesting beach remaining in the eastern Pacific (Playa Grande) has been evolutionarily selected as an optimal nesting site owing to favourable ocean currents that enhance hatchling survival. PMID:22378803

  13. Preliminary description of quaternary and late pliocene surficial deposits at Yucca Mountain and vicinity, Nye County, Nevada

    SciTech Connect

    Hoover, D.L.

    1989-11-01

    The Yucca Mountain area, in the south-central part of the Great Basin, is in the drainage basin of the Amargosa River. The mountain consists of several fault blocks of volcanic rocks that are typical of the Basin and Range province. Yucca Mountain is dissected by steep-sided valleys of consequent drainage systems that are tributary on the east side to Fortymile Wash and on the west side to an unnamed wash that drains Crater Flat. Most of the major washes near Yucca Mountain are not integrated with the Amargosa River, but have distributary channels on the piedmont above the river. Landforms in the Yucca Mountain area include rock pediments, ballenas, alluvial pediments, alluvial fans, stream terraces, and playas. Early Holocene and older alluvial fan deposits have been smoothed by pedimentation. The semiconical shape of alluvial fans is apparent at the junction of tributaries with major washes and where washes cross fault and terrace scarps. Playas are present in the eastern and southern ends of the Amargosa Desert. 39 refs., 9 figs., 1 tab.

  14. Late Holocene marine terraces of the Cartagena region, southern Caribbean: The product of neotectonism or a former high stand in sea-level?

    NASA Astrophysics Data System (ADS)

    Ignacio Martínez, J.; Yokoyama, Yusuke; Gomez, Andres; Delgado, Adriana; Matsuzaki, Hiroyuki; Rendon, Esteban

    2010-03-01

    The detailed stratigraphic survey and paleontological study (mollusks, corals, foraminifera and ostracods) of four low-level, ˜3 m, marine terrace sections: Punta Canoas, Manzanillo del Mar, Playa de Oro, and Tierra Bomba Island, from the Cartagena region, southern Caribbean, supplemented with 22 radiocarbon dates, reveals that the northern terraces were deposited as parasequences in a clastic depositional system compared to the Tierra Bomba Island succession that was deposited in a carbonate depositional system between ˜3600 and ˜1700 cal yrs BP. Drier conditions and the southern location of the ITCZ at about 3 ka triggered stronger easterly Trades and more dynamic southwestward sediment drift fed by the Magdalena River mouth, thus promoting the formation of sand spits that ultimately isolated the Cienaga de Tesca coastal lagoon from the Caribbean Sea. Our estimates support the hypothesis that the present position of the terraces is the product of neotectonism rather than a higher 3 ka, sea-level. Upheaval of the terraces varies between ˜3.8 mmyr -1 at Punta Canoas and ˜2.2 mmyr -1 at Tierra Bomba to ˜1.5 mmyr -1 at Manzanillo del Mar and Playa de Oro terraces. Our study corroborates previous contentions on the role of mud diapirism and the dynamics of the Dique Fault as late Holocene upheaval mechanisms.

  15. ERTS-1 evaluation of natural resources management applications in the Great Basin

    NASA Technical Reports Server (NTRS)

    Tueller, P. T.; Lorain, G.

    1973-01-01

    The relatively cloud free weather in the Great Basin has allowed the accumulation of several dates of excellent ERTS-1 imagery. Mountains, valleys, playas, stream courses, canyons, alluvial fans, and other landforms are readily delineated on ERTS-1 imagery, particularly with MSS-5. Each band is useful for identifying and studying one or more natural resource features. For example, crested wheatgrass seedings were most easily identified and measured on MSS-7. Color enhancements simulating CIR were useful for depicting meadow and phreatophytic vegetation along water bodies and stream courses. Work is underway to inventory and monitor wildfire areas by age and successional status. Inventories have been completed on crested wheatgrass seedings over the entire State of Nevada, and inventories of playa surfaces, water surfaces, phreatophytic vegetation, snow cover, meadows, and other features is continuing. Vegetation ecotones are being delineated for vegetation mapping. The pinyon/juniper-northern desert shrub ecotone has been identified with considerable success. Phenology changes can be used to describe vegetation changes for management.

  16. Small mammals associated with colonies of black-tailed prairie dogs (Cynomys ludovicianus) in the Southern High Plains

    USGS Publications Warehouse

    Pruett, A.L.; Boal, C.W.; Wallace, M.C.; Whitlaw, H.A.; Ray, J.D.

    2010-01-01

    We compared diversity and abundance of small mammals at colonies of black-tailed prairie dogs (Cynomys ludovicianus) and paired non-colony sites. Of colonies of black-tailed prairie dogs in our study area, >80 were on slopes of playa lakes; thus, we used sites of colonies and non-colonies that were on slopes of playa lakes. We trapped small mammals on 29 pairs of sites. Overall abundance did not differ between types of sites, but some taxa exhibited associations with colonies (Onychomys leucogaster) or non-colonies (Chaetodipus hispidus, Reithrodontomys, Sigmodon hispidus). Diversity and evenness of small mammals did not differ between colonies and non-colonies in 2002, but were higher on non-colonies in 2003. Although we may not have detected some rare or infrequently occurring species, our data reveal differences in diversity and evenness of more common species among the types of sites. Prairie dogs are touted as a keystone species with their colonies associated with a greater faunal diversity than adjacent lands. Our findings contradict several studies reporting greater diversity and abundance of small mammals at colonies of prairie dogs. We suggest that additional research across a wider landscape and incorporating landscape variables beyond the immediate trapping plot may further elucidate interspecific associations between black-tailed prairie dogs and species of small rodents.

  17. Diagenetic contrast of sandstones in hydrocarbon prospective Mesozoic rift basins (Ethiopia, UK, USA)

    NASA Astrophysics Data System (ADS)

    Wolela, A.

    2014-11-01

    Diagenetic studied in hydrocarbon-prospective Mesozoic rift basins were carried out in the Blue Nile Basin (Ethiopia), Ulster Basin (United Kingdom) and Hartford Basin (United States of America). Alluvial fan, single and amalgamated multistorey meandering and braided river, deep and shallow perennial lake, shallow ephemeral lake, aeolian and playa mud-flat are the prominent depositional environments. The studied sandstones exhibit red bed diagenesis. Source area geology, depositional environments, pore-water chemistry and circulation, tectonic setting and burial history controlled the diagenetic evolution. The diagenetic minerals include: facies-related minerals (calcrete and dolocrete), grain-coating clay minerals and/or hematite, quartz and feldspar overgrowths, carbonate cements, hematite, kaolinite, illite-smectite, smectite, illite, chlorite, actinolite, laumontite, pyrite and apatite. Diversity of diagenetic minerals and sequence of diagenetic alteration can be directly related to depositional environment and burial history of the basins. Variation in infiltrated clays, carbonate cements and clay minerals observed in the studied sandstones. The alluvial fan and fluviatile sandstones are dominated by kaolinite, illite calcite and ferroan calcite, whereas the playa and lacustrine sandstones are dominated by illite-smectite, smectite-chlorite, smectite, chlorite, dolomite ferroan dolomite and ankerite. Albite, pyrite and apatite are predominantly precipitated in lacustrine sandstones. Basaltic eruption in the basins modified mechanically infiltrated clays to authigenic clays. In all the studied sandstones, secondary porosity predominates over primary porosity. The oil emplacement inhabited clay authigenesis and generation of secondary porosity, whereas authigenesis of quartz, pyrite and apatite continued after oil emplacement.

  18. Antimicrobial Susceptibilities of Aeromonas spp. Isolated from Environmental Sources▿

    PubMed Central

    Huddleston, Jennifer R.; Zak, John C.; Jeter, Randall M.

    2006-01-01

    Aeromonas spp. are ubiquitous aquatic bacteria that cause serious infections in both poikilothermic and endothermic animals, including humans. Clinical isolates have shown an increasing incidence of antibiotic and antimicrobial drug resistance since the widespread use of antibiotics began. A total of 282 Aeromonas pure cultures were isolated from both urban and rural playa lakes in the vicinity of Lubbock, Texas, and several rivers in West Texas and New Mexico. Of these, at least 104 were subsequently confirmed to be independent isolates. The 104 isolates were identified by Biolog and belonged to 11 different species. The MICs of six metals, one metalloid, five antibiotics, and two antimicrobial drugs were determined. All aeromonads were sensitive to chromate, cobalt, copper, nickel, zinc, cefuroxime, kanamycin, nalidixic acid, ofloxacin, tetracycline, and sulfamethoxazole. Low incidences of trimethoprim resistance, mercury resistance, and arsenite resistance were found. Dual resistances were found in 5 of the 104 Aeromonas isolates. Greater numbers of resistant isolates were obtained from samples taken in March versus July 2002 and from sediment versus water. Plasmids were isolated from selected strains of the arsenite- and mercury-resistant organisms and were transformed into Escherichia coli XL1-Blue MRF′. Acquisition of the resistance phenotypes by the new host showed that these resistance genes were carried on the plasmids. Mercury resistance was found to be encoded on a conjugative plasmid. Despite the low incidence of resistant isolates, the six playa lakes and three rivers that were sampled in this study can be considered a reservoir for antimicrobial resistance genes. PMID:16950901

  19. Global analysis of the effect of local climate on the hatchling output of leatherback turtles

    NASA Astrophysics Data System (ADS)

    Santidrián Tomillo, Pilar; Saba, Vincent S.; Lombard, Claudia D.; Valiulis, Jennifer M.; Robinson, Nathan J.; Paladino, Frank V.; Spotila, James R.; Fernández, Carlos; Rivas, Marga L.; Tucek, Jenny; Nel, Ronel; Oro, Daniel

    2015-11-01

    The most recent climate change projections show a global increase in temperatures along with precipitation changes throughout the 21st century. However, regional projections do not always match global projections and species with global distributions may exhibit varying regional susceptibility to climate change. Here we show the effect of local climatic conditions on the hatchling output of leatherback turtles (Dermochelys coriacea) at four nesting sites encompassing the Pacific, Atlantic and Indian Oceans. We found a heterogeneous effect of climate. Hatchling output increased with long-term precipitation in areas with dry climatic conditions (Playa Grande, Pacific Ocean and Sandy Point, Caribbean Sea), but the effect varied in areas where precipitation was high (Pacuare, Caribbean Sea) and was not detected at the temperate site (Maputaland, Indian Ocean). High air temperature reduced hatchling output only at the area experiencing seasonal droughts (Playa Grande). Climatic projections showed a drastic increase in air temperature and a mild decrease in precipitation at all sites by 2100. The most unfavorable conditions were projected for Sandy Point where hatching success has already declined over time along with precipitation levels. The heterogeneous effect of climate may lead to local extinctions of leatherback turtles in some areas but survival in others by 2100.

  20. Global analysis of the effect of local climate on the hatchling output of leatherback turtles.

    PubMed

    Santidrián Tomillo, Pilar; Saba, Vincent S; Lombard, Claudia D; Valiulis, Jennifer M; Robinson, Nathan J; Paladino, Frank V; Spotila, James R; Fernández, Carlos; Rivas, Marga L; Tucek, Jenny; Nel, Ronel; Oro, Daniel

    2015-11-17

    The most recent climate change projections show a global increase in temperatures along with precipitation changes throughout the 21(st) century. However, regional projections do not always match global projections and species with global distributions may exhibit varying regional susceptibility to climate change. Here we show the effect of local climatic conditions on the hatchling output of leatherback turtles (Dermochelys coriacea) at four nesting sites encompassing the Pacific, Atlantic and Indian Oceans. We found a heterogeneous effect of climate. Hatchling output increased with long-term precipitation in areas with dry climatic conditions (Playa Grande, Pacific Ocean and Sandy Point, Caribbean Sea), but the effect varied in areas where precipitation was high (Pacuare, Caribbean Sea) and was not detected at the temperate site (Maputaland, Indian Ocean). High air temperature reduced hatchling output only at the area experiencing seasonal droughts (Playa Grande). Climatic projections showed a drastic increase in air temperature and a mild decrease in precipitation at all sites by 2100. The most unfavorable conditions were projected for Sandy Point where hatching success has already declined over time along with precipitation levels. The heterogeneous effect of climate may lead to local extinctions of leatherback turtles in some areas but survival in others by 2100.

  1. Geomorphic and land cover identification of dust sources in the eastern Great Basin of Utah, U.S.A.

    NASA Astrophysics Data System (ADS)

    Hahnenberger, Maura; Nicoll, Kathleen

    2014-01-01

    This study identifies anthropogenically disturbed areas and barren playa surfaces as the two primary dust source types that repeatedly contribute to dust storm events in the eastern Great Basin of western Utah, U.S.A. This semi-arid desert region is an important contributor to dust production in North America, with this study being the first to specifically identify and characterize regional dust sources. From 2004 to 2010, a total of 51 dust event days (DEDs) affected the air quality in Salt Lake City, UT. MODIS satellite imagery during 16 of these DEDs was analyzed to identify dust plumes, and assess the characteristics of dust source areas. A total of 168 plumes were identified, and showed mobilization of dust from Quaternary deposits located within the Bonneville Basin. This analysis identifies 4 major and 5 secondary source areas for dust in this region, which produce dust primarily during the spring and fall months and during moderate or greater drought conditions, with a Palmer Drought Index (PDI) of - 2 or less. The largest number of observed dust plumes (~ 60% of all plumes) originated from playas (ephemeral lakes) and are classified as barren land cover with a silty clay soil sediment surface. Playa surfaces in this region undergo numerous recurrent anthropogenic disturbances, including military operations and anthropogenic water withdrawal. Anthropogenic disturbance is necessary to produce dust from the vegetated landscape in the eastern Great Basin, as evidenced by the new dust source active from 2008 to 2010 in the area burned by the 2007 Milford Flat Fire; this fire was the largest in Utah's history due to extensive cover of invasive cheatgrass (Bromus tectorum) along with drought conditions. However, dust mobilization from the Milford Flat Burned Area was limited to regions that had been significantly disturbed by post-fire land management techniques that consisted of seeding, followed by chaining or tilling of the soil. Dust storms in the eastern

  2. Hydrogeologic setting and hydrologic data of the Smoke Creek Desert basin, Washoe County, Nevada, and Lassen County, California, water years 1988-90

    USGS Publications Warehouse

    Maurer, D.K.

    1993-01-01

    Smoke Creek Desert is a potential source of water for urban development in Washoe County, Nevada. Hydrogeologic data were collected from 1988 to 1990 to learn more about surface- and ground-water flow in the basin. Impermeable rocks form a boundary to ground-water flow on the east side of the basin and at unknown depths at the base of the flow system. Permeable volcanic rocks on the west and north sides of the basin represent a previously unrecognized aquifer and provide potential avenues for interbasin flow. Geophysical data indicate that basin-fill sediments are about 2,000 feet thick near the center of the basin. The geometry of the aquifers, however, remains largely unknown. Measurements of water levels, pressure head, flow rate, water temperature, and specific conductance at 19 wells show little change from 1988 to 1990. Chemically, ground water begins as a dilute sodium and calcium bicarbonate water in the mountain blocks, changes to a slightly saline sodium bicarbonate solution beneath the alluvial fans, and becomes a briny sodium chloride water near the playa. Concentrations of several inorganic constituents in the briny water near the playa commonly exceed Nevada drinking-water standards. Ground water in the Honey Lake basin and Smoke Creek Desert basin has similar stable-isotope composition, except near Sand Pass. If interbasin flow takes place, it likely occurs at depths greater than 400-600 feet beneath Sand Pass or through volcanic rocks to the north of Sand Pass. Measure- ments of streamflow indicate that about 2,800 acre-feet/year discharged from volcanic rocks to streamflow and a minimum of 7.300 acre-feet/year infiltrated and recharged unconsolidated sediments near Smoke, Buffalo, and Squaw Creeks during the period of study. Also about 1,500 acre-feet per year was lost to evapotranspiration along the channel of Smoke Creek, and about 1,680 acre-feet per year of runoff from Smoke, Buffalo, and Squaw Creeks was probably lost to evaporation from the

  3. Utilizing an Extraterrestrial Analogue to Predict Sediment Migration on Frenchman Flat due to Convective Vortex (Dust Devil) Activity

    NASA Astrophysics Data System (ADS)

    McGee, B. W.

    2006-12-01

    A synthesis of terrestrial and Martian data suggests that a convective vortex, or "dust devil," is a significant, non-random terrestrial eolian sediment transport phenomenon, which has implications for sediment-based migration of radionuclides on Frenchman Flat playa, a 20 square-mile mountain-bounded dry lake bed approximately centered in Frenchman Flat on the Nevada Test Site (NTS). Planetary scientists are often forced to rely on terrestrial analogues to begin characterizing extraterrestrial processes. However, as the planetary database matures, an increasing number of well-characterized extraterrestrial analogues for terrestrial processes will become available. Such analogues may provide a convenient means to investigate poorly understood or otherwise inaccessible terrestrial phenomena. Historical atmospheric nuclear experiments conducted from 1951 to 1962 deposited radionuclides into surface sediments across parts of Frenchman Flat playa, where dust devils are known to commonly occur, especially during the summer months. Recent information from both terrestrial and Martian studies yields that dust devils can be significant contributors to both the local eolian sediment transport regime and the regional climate system. Additionally, the use of terrestrial desert environments as Martian analogues, as well as the recent, unique discovery of Mars-like dust devil tracks in Africa, has established a working correlation between Earth, Mars, and the dust devil phenomenon. However, while the difficulty in tracking dust devil paths on Earth has hindered the determination of any net sediment transport due to dust devils, the dramatic albedo contrast in disturbed sediment on Mars lends to the formation of persistent, curvilinear dust devil tracks. These tracks illustrate that in zones of preferential formation, dust devils possess non-random orientations over seasonal timescales with respect to prevailing wind. By calibrating these Martian orientations with meteorological

  4. Soil Moisture Dynamics and Evaporation in Arid Intermountain Environments

    NASA Astrophysics Data System (ADS)

    Hang, C.; Pardyjak, E.; Nadeau, D. F.; Jensen, D. D.; Hoch, S.

    2014-12-01

    Mountain flows have been studied for several decades now and it is safe to say that their main features are well understood under steady conditions and over idealized terrain. The Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program was designed to better understand atmospheric fluid dynamics across all scales over realistic mountainous terrain as well as under transient and steady conditions. As part of MATERHORN, a large field campaign was conducted in May 2013. The main study area, a playa site, covers an area of several hundred square kilometers. It is mostly devoid of vegetation, characterized by a flat surface, shallow water table and a heterogeneous soil moisture spatial distribution even in dry conditions. Recent studies have shown that soil moisture plays a critical role in the dynamics of mountain flows, but a detailed understanding of these has not been sufficiently quantified. The objectives of this study are thus: 1) to quantify the spatial heterogeneity of soil moisture on the playa site; 2) to describe how soil moisture affects the surface energy balance; 3) to identify the key controlling mechanisms on evaporation after a rain event in an arid area; 4) to explore the existence of nocturnal evaporation and investigate its main driving factors. To do this, we applied the gravimetric method to measure volumetric water content in the surface soil layer (0 - 2 cm and 4 - 6 cm) twice per 24-h intensive observation period at 17 sites evenly distributed on a 180 x 240 m grid. Near-surface atmospheric variables as well as ground heat-flux were also measured by a flux tower located close to the soil sampling sites. Preliminary data analysis reveals that the highest spatial variability in surface soil moisture is found under dry conditions. Our results also show that decreasing surface albedo with increasing soil moisture sustained a powerful positive feedback loop promoting large evaporation rates. Finally, it was found that while

  5. Late Cenozoic geomorphologic signal of Andean forearc deformation and tilting associated with the uplift and climate changes of the Southern Atacama Desert (26°S 28°S)

    NASA Astrophysics Data System (ADS)

    Riquelme, Rodrigo; Hérail, Gérard; Martinod, Joseph; Charrier, Reynaldo; Darrozes, José

    2007-05-01

    We analyze remarkable examples of the large (˜ 10,000 km 2) and local-scale (˜ 100 km 2) landscape forms related to Late Cenozoic geomorphologic evolution of the Andean forearc region in the Southern Atacama Desert. We also consider the continental sedimentary deposits, so-called "Atacama Gravels", which are related to the degradation of the landscape during the Neogene. Our analysis integrates 1:50,000 field cartography, Landsat TM images observations, ˜ 1:1000 sedimentary logging data, and 50 m horizontal resolution topographic data to reconstruct the Late Cenozoic geomorphologic evolution of this region and discuss the factors that control it, i.e., Miocene aridification of the climate and Neogene Central Andean uplift. We determine that the Precordillera was already formed in the Oligocene and most of the present-day altitude of the Precordillera was reached before that time. Afterward, five episodes of geomorphologic evolution can be differentiated: (1) the development of an Oligocene deep incised drainage system cutting the uplifted Precordillera (up to 2000 m of vertical incision) and connecting it to the Ocean; followed by (2) the infilling of deep incised valleys by up to 400 m of Atacama Gravels. This infill started in the Early Miocene with the development of fluvial deposition and finished in the Middle Miocene with playa and playa lake depositions. We propose that playa-related deposition occurs in an endorheic context related to tectonic activity of the Atacama Fault System and Coastal Cordillera uplift. However, the upward sedimentologic variation in the Atacama Gravels evidences a progressive aridification of the climate. Subsequently, we have identified the effects of the Middle-Upper Miocene slow tectonic deformation: the Neogene Andean uplift is accommodated by a tilting or flexuring of the inner-forearc (Central Depression and Precordillera) related to some hundreds of meters of uplift in the Precordillera. This tilting or flexuring results

  6. Sedimentary archives of extreme flooding events in the Northeastern Caribbean

    NASA Astrophysics Data System (ADS)

    Woodruff, J. D.; Donnelly, J. P.; Scileppi, E.

    2004-12-01

    Flooding associated with both hurricanes and tsunamis can be extremely hazardous to coastal communities. Accurately reconstructing the past history and intensity of these extreme events is valuable when assessing future risks to specific coastal regions. Overwash deposits preserved within backbarrier lagoons and salt ponds can provide a means for documenting previous flooding activity; however, the details of how these individual flooding events are recorded within these environments is still not completely understood. An analysis of sediment cores collected from a lagoon system in the Northeastern Caribbean (Laguna Playa Grande, Vieques, Puerto Rico) reveal coarse-grained deposits interlaminated within fine-grain lagoon sediments. These coarse-grained laminae consist of beach and nearshore sediments and can be mapped across the lagoon. These coarse-grained strata are likely overwash deposits that may provide a high-resolution record of extreme flooding events in the region over the last 5000 years. Understanding the sedimentary record of historical events of known intensity and duration is necessary, however, in order to make inferences about the cause of prehistoric coarse-grained layers. Vieques has experienced relatively little coastal development and contains a well documented history of storm and tsunami activity since its colonization in the 16th century. The island thus provides an excellent opportunity to study how recent extreme flooding events have been preserved in a natural lagoon system. Overwash deposits preserved at Laguna Playa Grande over the last 200 years are analyzed in order to identify which historically documented flooding events appear to have left a sedimentological record. These deposits are initially identified based on high resolution grain-size analysis and x-radiographic imaging. Activity levels for Pb-210 and C-137 are measured to date recent sediments (over the past 200 yrs) and to link individual coarse-grained strata with

  7. Properties of solonetzes on terraces of salt lakes Bulukhta and Khaki in the Caspian Lowland

    NASA Astrophysics Data System (ADS)

    Shabanova, N. P.; Lebedeva, M. P.

    2016-06-01

    A comparative assessment of pedogenetic processes in solonetzes (Calcic Gypsic Salic Solonetzes (Siltic, Albic, Cutanic, Differentic)) developing on terraces of lake depressions within the Volga-Ural interfluve of the Caspian Lowland has been performed on the basis of data on their macro- and micromorphological features and chemical, physicochemical, and physical properties. The studied soils have number of common characteristics shaped by the humus-accumulative, solonetzic, eluvial-illuvial, calcification, and gypsification processes. However, it is shown that macro- and micromorphological indicators of solonetzic processes (the development of clay-humus coatings and the character of structural units in the solonetzic (B) horizon) do not always agree with the modern physicochemical conditions of the development of this process. This is explained by differences in the degree and chemistry of the soil salinization and the depth and salinity of the groundwater. Solonetzes developing on the second terrace of Playa Khaki are distinguished by the highest water content and maximum thickness of the horizons depleted of soluble salts. They are characterized by the well-pronounced humus-accumulative process leading to the development of the light-humus (AJ) horizon. In other solonetzes, the accumulation of humus is weaker, and their topsoil part can be diagnosed as the solonetzic-eluvial (SEL) horizon. Active solodic process and illuviation of organomineral substances with the development of thick coatings and infillings in the B horizon are also typical of solonetzes on the second terrace of Playa Khaki. Micromorphological data indicate that, at present, layered clayey coatings in these soils are subjected to destruction and in situ humification owing to the active penetration of plant roots into the coatings with their further biogenic processing by the soil microfauna. The process of gleyzation (as judged from the number of Fe-Mn concentrations) is most active in

  8. [Tap water as a dietary source of exposure to fluoride in Tenerife; risk assessment].

    PubMed

    González Sacramento, Nazaret; Rubio Armendáriz, Carmen; Gutiérrez Fernández, Ángel José; Luis González, Gara; Hardisson de la Torre, Arturo; Revert Girones, Consuelo

    2015-04-01

    Introducción: el agua de consumo humano es la principal fuente de exposición al fluoruro para la población. De acuerdo con el Real Decreto 140/2003, el contenido en fluoruro en el agua de consumo humano no debe superar el valor paramétrico de 1,5 mg/L. Históricamente, ciertas aguas de consumo en Tenerife han superado este valor debido a sus características geológicas/volcánicas. El flúor juega un papel importante en la prevención de la caries dental. Sin embargo, la exposición crónica a concentraciones superiores a 1,5 mg/L en el agua de bebida puede provocar trastornos como la fluorosis dental. Objetivos: determinar la cantidad de fluoruro en el agua de consumo humano de 11 municipios del norte de la isla de Tenerife que en el momento del estudio superaba el valor paramétrico de fluoruro y estimar y evaluar toxicológicamente las ingestas diarias a partir del consumo de agua considerando las IDR (Ingestas Diarias Recomendadas) establecidas en España para distintos grupos poblacionales. Método: 44 muestras de aguas de abastecimiento público recogidas en los 11 municipios objeto del estudio fueron analizadas usando la determinación potenciométrica de fluoruro mediante el uso de un electrodo de ión selectivo. Resultados: 9 de los 11 municipios las aguas de abasto presentaron concentraciones de fluoruro medias que superaron el valor paramétrico fijado por la legislación española. Considerando un consumo medio diario de agua de 2 L, la ingesta diaria recomendada (IDR) para mujeres (3 mg/día) es superada en 9 de los 11 municipios y la IDR para hombres (4 mg/día) es superada en 5 de los 11 municipios. Considerando un consumo medio diario de agua de 1,5 L, la IDR establecida para los niños de 2 a 3 años (0,7 mg/día) es superada ampliamente en todos los municipios. Conclusiones: los resultados obtenidos evidencian el problema de salud pública existente en la isla de Tenerife y justifican las restricciones de consumo establecidas por la Direcci

  9. [Some economic and demographic norms of workers from three settled municipalities].

    PubMed

    Barrientos, G E; Pastor, M E

    1991-09-01

    Preliminary data on household structures of proletarian and semiproletarian workers in 3 municipios of the state of Puebla, Mexico, are presented. This work is part of a larger study of the 5 municipios with the highest proportion of industrial workers in the state of Puebla. Among the 3 municipios in the present study, Puebla contained 48.4% of the state's industrial workers, Tehuacan 6.9%, and Cholula 3.9%. A structured questionnaire was used during interviews with 27 male and 25 female factory workers in Puebla, 24 male and 15 female workers in Cholula, and 25 male and 20 female factory workers in Tehuacan. 16% of households of industrial workers in Puebla and Cholula supplemented their wage income with agricultural work, compared to 27% in Tehuacan. 10 of the workers, all women, were under 20 years old. 73% of women workers were under 30 years old, compared to 34% of the male workers. Women workers virtually disappeared after 40 years. Less educated women tend to enter the labor force at early ages and use their incomes to aid the parental budget. The tendency is reinforced by the preference of factories for a very young female labor force that also stops working a young age due to marriage. Women supported households alone in 8 cases and with the aid of other women in 4 cases. 52 households depended on the income of 1 man and another 17 on the income of more than 1 man. 48 of the women but only 7 of the men belonged to households in which both men and women were economically active. Households supported by just 1 man tended to be quite large. The data suggest a postponement of the age at 1st pregnancy among female workers.

  10. The effects of 3 environmental risks on mortality disparities across Mexican communities

    PubMed Central

    Stevens, Gretchen A.; Dias, Rodrigo H.; Ezzati, Majid

    2008-01-01

    The disparities in the burden of ill health caused by environmental risks should be an important consideration beyond their aggregate population effects. We used comparative risk assessment methods to calculate the mortality effects of unsafe water and sanitation, indoor air pollution from household solid fuel use, and ambient urban particulate matter pollution in Mexico. We also estimated the disparities in mortality caused by each risk factor, across municipios (counties) of residence and by municipio socioeconomic status (SES). Data sources for the analysis were the national census, population-representative health surveys, and air quality monitoring for risk factor exposure; systematic reviews and meta-analyses of epidemiological studies for risk factor effects; and vital statistics for disease-specific mortality. During 2001–2005, unsafe water and sanitation, household solid fuel use, and urban particulate matter pollution were responsible for 3,000, 3,600, and 7,600 annual deaths, respectively. Annual child mortality rates would decrease by 0.2, 0.1, and 0.1 per 1,000 children, and life expectancy would increase by 1.0, 1.2, and 2.4 months, respectively, in the absence of these environmental exposures. Together, these risk factors caused 10.6% of child deaths in the lowest-SES communities (0.9 deaths per 1,000 children), but only 4.0% in communities in the highest-SES ones (0.1 per 1,000). In the 50 most-affected municipios, these 3 exposures were responsible for 3.2 deaths per 1,000 children and a 10-month loss of life expectancy. The large disparities in the mortality effects of these 3 environmental risks should form the basis of interventions and environmental monitoring programs. PMID:18974224

  11. 12. Photocopy of drawing (this photograph is an 8' x ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. Photocopy of drawing (this photograph is an 8' x 10' contact print; May 12, 1982 revision of a January 18, 1974 as built drawing by F. Marquez Ramos, in possesion of the Bridge Evaluation Office of the Puerto Rico Department of Transportation and Public Works) BRIDE (sic) OVER RIO GRANDE DE LOIZA, ROAD NO. 980 KM. 10.6 - Puente de la Marina, San Lorenzo-Florida & Cerro Gordo Neighborhoods, spanning Rio Grande de Loiza River at Narciso Varona-Suarez Street, San Lorenzo, San Lorenzo Municipio, PR

  12. [Internal migration].

    PubMed

    Borisovna, L

    1991-06-01

    Very few studies have been conducted that truly permit explanation of internal migration and it repercussions on social and economic structure. It is clear however that a profound knowledge of the determinants and consequences of internal migration will be required as a basis for economic policy decisions that advance the goal of improving the level of living of the population. the basic supposition of most studies of the relationship of population and development is that socioeconomic development conditions demographic dynamics. The process of development in Mexico, which can be characterized by great heterogeneity, consequently produces great regional disparities. At the national level various studies have estimated the volume of internal migration in Mexico, but they have usually been limited to interstate migration because the main source of data, the census, is classified by states. But given the great heterogeneity within states in all the elements related to internal migration, it is clear that studies of internal migration within states are also needed. Such studies are almost nonexistent because of their technical difficulty. National level studies show that interstate migration increased significantly between 1940-80. The proportion of Mexicans living outside their states of birth increased by 558% in those years, compared to the 342% increase in the total Mexican population. Although Puebla has a high rate of increase, migration has kept it below Mexico's national growth rate. Migration between Puebla and other states and within Puebla has led to an increasing unevenness of spatial distribution. Between 1970-80, 57 of Puebla's municipios had growth rates above the state average of 2.8%/year, 6 had growth rates equal to the average, and 129 had growth rates that were below the average but not negative. 25 states with negative growth rates that were considered strongly expulsive. In 1980, 51.7% of the population was concentrated in the 57 municipios

  13. Boca de Potrerillos

    NASA Astrophysics Data System (ADS)

    Murray, William Breen

    Boca de Potrerillos is an archaeological site located in the municipio of Mina, Nuevo León, about 60 km. northwest of Monterrey, Mexicós third largest city. Its principal feature is one of the largest concentrations of petroglyphs in the country. Archaeoastronomical features include petroglyphic markers of the cardinal directions, dot configurations which count lunar synodic periods, and one of the earliest horizon calendars in North America. They indicate that the site was probably used for sky observation from the Middle Archaic time period onward and may represent evidence of the initial stages in the development of Mesoamerican numeration and astronomy.

  14. Geochemistry of Precambrian carbonates. V - Late Paleoproterozoic seawater

    NASA Technical Reports Server (NTRS)

    Veizer, Jan; Plumb, K. A.; Clayton, R. N.; Hinton, R. W.; Grotzinger, J. P.

    1992-01-01

    A study of mineralogy, chemistry, and isotopic composition of the Coronation Supergroup (about 1.9 Ga, NWT), Canada, and the McArthur Group (about 1.65 NT), Australia, is reported in order to obtain better constrained data for the first- and second-order variations in the isotopic composition of late Paleoproterozoic (1.9 +/- 0.2 Ga) seawater. Petrologically, both carbonate sequences are mostly dolostones. The McArthur population contains more abundant textural features that attest to the former presence of sulfates and halite, and the facies investigated represent ancient equivalents of modern evaporitic sabkhas and lacustrine playa lakes. It is suggested that dolomitization was an early diagenetic event and that the O-18 depletion of the Archean to late Paleoproterozoic carbonates is not an artifact of postdepositional alteration.

  15. Advances in water resources monitoring from space

    NASA Technical Reports Server (NTRS)

    Salomonson, V. V.

    1974-01-01

    Nimbus-5 observations indicate that over the oceans the total precipitable water in a column of atmosphere can be estimated to within + or - 10%, the liquid water content of clouds can be estimated to within + or - 25%, areas of precipitation can be delineated, and broad estimates of the precipitation rate obtained. ERTS-1 observations permit the measurement of snow covered area to within a few percent of drainage basin area and snowline altitudes can be estimated to within 60 meters. Surface water areas as small as 1 hectare can be inventoried over large regions such as playa lakes region of West Texas and Eastern New Mexico. In addition, changes in land use on water-sheds occurring as a result of forest fires, urban development, clear cutting, or strip mining can be rapidly obtained.

  16. Late Pleistocene woodlands in the Bolson de Mapimi: A refugium for the Chihuahuan Desert Biota?

    NASA Astrophysics Data System (ADS)

    Van Devender, Thomas R.; Burgess, Tony L.

    1985-11-01

    Packrat middens radiocarbon dated at 12,280 ± 345 and 12,700 ± 165 yr B.P. record expansions of junipers and papershell pinyon ( Pinus remota) into the desert lowlands of Durango and Coahuila, Mexico (26° N). Extralocal trees and shrubs presently occur 24-580 km in nearly all directions including more subtropical areas to the northeast and southeast. An equable Late Wisconsin climate marked by mild winters with increased precipitation and by cool summers with reduced summer monsoons is proposed. The extensive playas of the Bolson de Mapimi probably held water at that time. The Bolson de Mapimi was not a geographical refugium unaffected by glacial climates, although many Chihuahuan Desert plants and animals probably remain in situ as members of equable woodlands. Equable climates, low extinction rates, and repeated, rapid glacial/interglacial climatic fluctuations may have been important in the evolution and accumulation of species at lower latitudes.

  17. Simulating Groundwater Recharge Across the Southern High Plains

    NASA Astrophysics Data System (ADS)

    Smidt, S. J.; Haacker, E. M.; Kendall, A. D.; Hyndman, D. W.

    2015-12-01

    Quantifying recharge and water availability across the Southern High Plains is a difficult, but necessary, challenge for future groundwater and agricultural projections. Overland flow is not common due to limited precipitation, dry soils, and high evapotranspiration. The majority of runoff is temporarily stored in playa lakes, leading to the bulk of recharge across the region occurring in localized infiltration zones beneath these lakes. Despite the importance of regional recharge estimates, limited information exists that integrates complex characteristics of the land, climate, and hydrology in order to quantify recharge across the entire Southern High Plains aquifer. This study applies the Landscape Hydrology Model (LHM) to capture these characteristics and simulate surface water flow and groundwater recharge. This model simulates the complete water cycle across large regions, including irrigation estimates, establishing a framework to estimate recharge and groundwater availability in the Southern High Plains region. Results from this study can be used to predict the likely impacts of climate change and improve water management strategies.

  18. [Embrionary development of Strombus pugilis (Mesogastropoda: Strombidae) in the laboratory].

    PubMed

    Brito Manzano, N; Aldana Aranda, D

    2000-12-01

    Stages from oviposition to veliger hatching are described for Strombus pugilis under laboratory conditions. Two egg masses from Playa Seyba, México, (20 degrees 45' N, 91 degrees 45' W) were used (three sub-samples per mass). Each sub-sample was immersed in a 11 container at 29 +/- 1 degrees C. This description is based on stages known from Strombus gigas, which include number of: fertilized eggs, morulae, gastrulae, trochophore larvae with slow movements, larvae with primordium foot, larvae with eyes, larvae with statocyst and veliger larvae. Eggs with first division appeared five hours after oviposition in the three replicates of each mass, although in greatest number in one of the egg masses. Trochophore larvae with slow movements appear after 50-54 hours and veligers hatch after 90 hours. PMID:15266793

  19. A Wind-tunnel Study of Atmospheric Boundary-Layer Flow over Vegetated Surfaces to Suppress PM10 Emission on Owens (dry) Lake

    NASA Astrophysics Data System (ADS)

    Kim, Dae Seong; Cho, Greg H.; White, Bruce R.

    Dust storms on Owens (dry) Lake located 200 milesnortheast of Los Angeles, California, U.S.A., havecaused serious PM10 emission problems. Alaboratory-based experimental study was conducted toinvestigate the efficiency of ''vegetation cover'' onthe playa to suppress dust emission rates as part ofa mitigation plan.Erodible lakebed material and field vegetation (saltgrass) taken from Owens (dry) Lake were placed in awind tunnel to simulate near-surface wind flow in theatmospheric boundary layer. Vertical wind-speedprofiles and vertical PM10-concentration profileswere measured over six different levels of surfacevegetation cover. In order to understand the mechanismof aeolian particle transport and dust injection intothe atmosphere, the roughness parameter, z0, thefriction velocity, u*, and the surface dragcoefficient, CD, were carefully determined.

  20. Extrasolar Planets Observed with JWST and the ELTs

    NASA Technical Reports Server (NTRS)

    Deming, L. Drake

    2010-01-01

    The advent of cryogenic space-borne infrared observatories such as the Spitzer Space Telescope has lead to a revolution in the study of planets and planetary systems orbiting sun-like stars. Already Spitzer has characterized the emergent infrared spectra of close-in giant exoplanets using transit and eclipse techniques. The James Webb Space Telescope (JWST) will be able to extend these studies to superEarth exoplanets orbiting in the habitable zones of M-dwarf stars in the near solar neighborhood. The forthcoming ground-based Extremely Large Telescopes (ELTs) will playa key role in these studies, being especially valuable for spectroscopy at higher spectral resolving powers where large photon fluxes are needed. The culmination of this work within the next two decades will be the detection and spectral characterization of the major molecular constituents in the atmosphere of a habitable superEarth orbiting a nearby lower main sequence star.

  1. Lithium Resources for the 21st Century

    NASA Astrophysics Data System (ADS)

    Kesler, S.; Gruber, P.; Medina, P.; Keolian, G.; Everson, M. P.; Wallington, T.

    2011-12-01

    Lithium is an important industrial compound and the principal component of high energy-density batteries. Because it is the lightest solid element, these batteries are widely used in consumer electronics and are expected to be the basis for battery electric vehicles (BEVs), hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) for the 21st century. In view of the large incremental demand for lithium that will result from expanded use of various types of EVs, long-term estimates of lithium demand and supply are advisable. For GDP growth rates of 2 to 3% and battery recycling rates of 90 to 100%, total demand for lithium for all markets is expected to be a maximum of 19.6 million tonnes through 2100. This includes 3.2 million tonnes for industrial compounds, 3.6 million tonnes for consumer electronics, and 12.8 million tonnes for EVs. Lithium-bearing mineral deposits that might supply this demand contain an estimated resource of approximately 39 million tonnes, although many of these deposits have not been adequately evaluated. These lithium-bearing mineral deposits are of two main types, non-marine playa-brine deposits and igneous deposits. Playa-brine deposits have the greatest immediate resource potential (estimated at 66% of global resources) and include the Salar de Atacama (Chile), the source of almost half of current world lithium production, as well as Zabuye (China/Tibet) and Hombre Muerto (Argentina). Additional important playa-brine lithium resources include Rincon (Argentina), Qaidam (China), Silver Peak (USA) and Uyuni (Bolivia), which together account for about 35% of the estimated global lithium resource. Information on the size and continuity of brine-bearing aquifers in many of these deposits is limited, and differences in chemical composition of brines from deposit to deposit require different extraction processes and yield different product mixes of lithium, boron, potassium and other elements. Numerous other brines in playas

  2. Evolutionary characteristics of lakes and palaeoclimatic undulation in the Qaidam Basin, China

    NASA Astrophysics Data System (ADS)

    Huang, Qi; Teh-Lung, Ku; Phillips, Fred M.

    1993-03-01

    The Qaidam Basin is a tectonically controlled depression at 2700 m altitude on the northern margin of the Tibet Plateau. A succession of Neogene clastic sediments indicates lake depocentre migration from NW to SE. Towards late Pliocene, evaporative conditions developed with formation of gypsum, halite, celestite, mirabilite and bloedite. Continued deformation through Pleistocene developed a series of NW-SE trending domes and troughs. This setting continued to exert a controlling influence on basin and brine evolution and the progressive development of sulfate to chloride brines as dry conditions intensified in late Pleistocene, at the end of which, extensive flat floors were formed in Dalangtan, Qarhan and other playas. The model, which was set up based on the synthetic analyses, divides the fluctuating palaeoclimate since 750ka, B. P. into 11 warm and humid stages and 10 dry and cold stages. The water of the lakes evaporated during the dry-cold periods and were freshened during the warm-humid periods.

  3. Some examples of the utility of HCMM data in geologic remote sensing. [Heat Capacity Mapping Mission

    NASA Technical Reports Server (NTRS)

    Kahle, A. B.; Schieldge, J. P.; Abrams, M. J.; Alley, R. E.

    1981-01-01

    Examples of HCMM (Heat Capacity Mapping Mission) data in geologic remote sensing are presented, and the data set is composed of HCMM and aircraft digital scanner data and ground truth data from four western U.S. test sites. Data are used in the thermal model to test thermal data effectiveness, and changes in temperature with depth and time for dry soils are described by the model. It is found that the HCMM thermal inertia image is useful in the separability of bedrock and alluvium in Death Valley, and aa and pahoehoe flows in the Pisgah basalt flow. In a color composite of HCMM day temperature, night temperature, and day visible images of the Pisgah Crater test site, it is possible to distinguish alluvium, playa, aa and pahoehoe basalt flow, rhyolite intrusives, and other elements. Ground checking of units at a few points will extend capabilities to large areas and assist in creating telegeologic maps.

  4. Mesoscopic modeling of liquid water transport in polymer electrolyte fuel cells

    SciTech Connect

    Mukherjee, Partha P; Wang, Chao Yang

    2008-01-01

    A key performance limitation in polymer electrolyte fuel cells (PEFC), manifested in terms of mass transport loss, originates from liquid water transport and resulting flooding phenomena in the constituent components. Liquid water leads to the coverage of the electrochemically active sites in the catalyst layer (CL) rendering reduced catalytic activity and blockage of the available pore space in the porous CL and fibrous gas diffusion layer (GDL) resulting in hindered oxygen transport to the active reaction sites. The cathode CL and the GDL therefore playa major role in the mass transport loss and hence in the water management of a PEFC. In this article, we present the development of a mesoscopic modeling formalism coupled with realistic microstructural delineation to study the profound influence of the pore structure and surface wettability on liquid water transport and interfacial dynamics in the PEFC catalyst layer and gas diffusion layer.

  5. Recent Results From the Opportunity Rover's Exploration of Endeavour Crater, Mars

    NASA Technical Reports Server (NTRS)

    Arvidson, R. E.; Squyres, S. W.; Gellert, R.; Mittlefehldt, D. W.

    2014-01-01

    The Mars Exploration Rover Opportunity is beginning its 11th year of exploration and as of sol 3535 (1/3/14 UTC) has traversed 38,729 m (based on wheel turns) across the plains of Meridiani and the rim of the approx. 22 km wide Noachian Endeavour Crater. Opportunity has investigated ancient sulfate-rich sand-stones (Burns formation) that dominate the plains and formed in ancient playa and dune environments, characterized impact breccias (Shoemaker formation) and their aqueous alteration on Endeavour's Cape York rim segment, and investigated extensive aqueous alteration of rocks on Cape York's Matijevic Hill that stratigraphically underlie Shoemaker formation and predate the Endeavour-forming event. In this abstract results from Opportunity's recent exploration of Endeavour's rim are covered, focusing on comparing what was found on Matijevic Hill with observations acquired on Murray Ridge, where Opportunity will spend its sixth winter at Cook Haven.

  6. Number of oil-killed birds and fate of bird carcasses at crude oil pits in Texas

    USGS Publications Warehouse

    Flickinger, Edward L.; Bunck, C.M.

    1987-01-01

    A survey was taken of bird losses in crude oil pits near the central Texas Gulf Coast and in northwestern Texas. At one pit near the Texas Coast, 297 bird carcasses (largely ducks) were counted. Duck losses from oil pollution in northwestern Texas occurred largely in playa basins of the Permian Basin south of the Panhandle. To determine the fate of birds that die in oil pits, 40 carcasses of nine bird species were placed in two crude oil pits near the central Texas Coast in October (19) 1981 and December (15) 1981 and April (6) 1982 and studied for 5 months. Rate of sinking and disappearance of carcasses were positively related to carcass size. In a comparison of three seasons, the time required for a carcass to disappear was longer in winter when oil temperatures were lowest and shorter in spring and fall when oil temperatures were highest.

  7. Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of the Lake Manix Basin, Mojave Desert: Guidebook for Fall Field Trip, Friends of the Pleistocene, Pacific Cell, October 4-7, 2007

    USGS Publications Warehouse

    Reheis, Marith C.; Miller, David M.; Redwine, Joanna L.

    2007-01-01

    The 2007 field trip of the Pacific Cell, Friends of the Pleistocene, visited features of the Quaternary geology and geomorphology of the Lake Manix basin in the Mojave Desert. This report is the guidebook for this trip and includes some discussion of relations observable along the road and at various field trip stops. The Mojave River originates in the San Bernardino Mountains and in high-water years flows north and east to its terminus in Silver Lake playa north of Baker, Calif. Along this course, the river passes through or near several basins that were internally drained prior to integration by the Mojave River, including the Victorville, Harper, Manix, and Soda Lake basins. Sediments in the Lake Manix basin record Mojave River discharge and lake fluctuations that began during the middle Pleistocene and continued through most of the late Pleistocene.

  8. Investigación del USGS sobre el ecosistema de arrecifes de coral en el Atlántico

    USGS Publications Warehouse

    Kuffner, Ilsa B.; Yates, Kimberly K.; Zawada, David G.; Richey, Julie N.; Kellogg, Christina A.; Toth, Lauren T.; Torres-Garcia, Legna M.

    2015-10-23

    Los arrecifes de coral son estructuras sólidas, biomineralizadas que protegen comunidades costeras actuando como barreras protectoras de peligros tales como los huracanes y los tsunamis. Estos proveen arena a las playas a través de procesos naturales de erosión, fomentan la industria del turismo, las actividades recreacionales y proveen hábitats pesqueros esenciales. La conti-nua degradación mundial de ecosistemas de arrecifes de coral está bien documentada. Existe la necesidad de enfoque y organización de la ciencia para entender los procesos complejos físicos y biológicos e interacciones que están afectando el estado de los arrecifes coralinos y su capacidad para responder a un entorno cambiante.

  9. A quantitative model of ground-water flow during formation of tabular sandstone uranium deposits

    USGS Publications Warehouse

    Sanford, R.F.

    1994-01-01

    Presents a quantitative simulation of regional groundwater flow during uranium deposition in the Westwater Canyon Member and Jackpile Sandstone Member of the Upper Jurassic Morrison Formation in the San Juan basin. Topographic slope, shoreline position, and density contrasts in the lake and pore fluids controlled the directions of flow and recharge-discharge areas. The most important results for uranium ore deposit formation are that regional groundwater discharged throughout the basin, regional discharge was concentrated along the shore line or playa margin, flow was dominantly gravity driven, and compaction dewatering was negligible. A strong association is found between the tabular sandstone uranium deposits and major inferred zones of mixed local and regional groundwater discharge. -from Author

  10. Thermal Targets for Satellite Calibration

    SciTech Connect

    Villa-Aleman, E.

    2001-01-10

    The Savannah River Technology Center (SRTC) is currently calibrating the Multispectral Thermal Imager (MTI) satellite sponsored by the Department of Energy. The MTI imager is a research and development project with 15 wavebands in the visible, near-infrared, short-wave infrared, mid-wave infrared and long-wave infrared spectral regions. A plethora of targets with known temperatures such as power plant heated lakes, volcano lava vents, desert playas and aluminized Mylar tarps are being used in the validation of the five thermal bands of the MTI satellite. SRTC efforts in the production of ''cold targets'' with aluminized Mylar tarps will be described. Visible and thermal imagery and wavelength dependent radiance measurements of the calibration targets will be presented.

  11. Fluvial sedimentary styles and associated depositional environments in the buntsandstein west of river rhine in saar area and pfalz (F.R. Germany) and vosges (France)

    NASA Astrophysics Data System (ADS)

    Dachroth, Wolfgang

    The Buntsandstein west of river Rhine in Saar area, Pfalz and Vosges consists of three fluvial magnacycles which are characterized by different associated non-alluvial environments. The stratigraphic sequence is divided by several unconformities reflecting tectonic movements which were connected with periods of extension of the depositional area. Two major phases and two minor events are recognized by the evaluation of the Pfalz unconformity and the Lothringen unconformity, and the Leuter unconformity and the Saar unconformity, respectively. The Lower Buntsandstein (including Zechstein) compries the first magnacycle and is built up of alluvial-fan deposits, fluvial braidplain sediments and marine to lagoonal deposits. Some aeolian sands as well as several palaeosols are also present. The palaeolandscape consists of alluvial fans seaming the margin of the basin and fluvial braidplains reaching from the toes of the fan belt to the centre of the depositional area which is occupied by a lagoonal sea that partially evolves into a playa-lake with progressive refreshment. The Middle Buntsandstein comprises the second magnacycle and is composed of an alternation of aeolian Dünnschichten and fluvial Felsbänke. The third facies are alluvial-fan deposits of palaeogeographically restricted distribution along the margins of the basin. The aeolian Dünnschichten originate in the marginal parts of chott-type depressions (in comparison with the recent Chott Djerid in Tunesia) where rising ground water moistens the dry sediments that are laid down on the playa floor and thus allows their enhanced preservation. In dry periods, wind-blown sand is spread out as plane sheets or as migrating wind ripple trains, or accumulates to barchanoid-type dunes that advance across the flat. Depending on supply of sand, all stages of transition between dune fields with only narrow interdune corridors between the ridges and interdune playas with isolated widely-spaced dunes are developed. The

  12. Technical report for the alkali lake ecological assessment, phase 1 reconnaissance (FY 91 and FY 92)

    SciTech Connect

    Linder, G.

    1993-03-01

    The report summarizes the results of three field survey trips (June and September 1991, May 1992) taken to investigate the ecological effects associated with the release of over a million gallons of hazardous waste from herbicide production on the Alkali Lake playa. Sampling of soil, sediment, groundwater, soil-dwelling invertebrates and vegetation confirmed that hazardous materials from the waste disposal area are migrating westerly within the shallow aquifer to West Alkali Lake. Two areas of dead vegetation were identified and permanently marked to determine if these areas are changing in size and location. Preliminary calculations using a linear food-chain model suggested that small mammalian herbivores would probably not display adverse effects due to dietary exposures to the contaminants. However, nestling shorebirds may be exposed to concentrations potentially associated with adverse biological effects.

  13. The SEMATECH Berkeley microfield exposure tool: learning a the 22-nm node and beyond

    SciTech Connect

    Naulleau, Patrick; Anderson, Christopher; Baclea-an, Lorie-Mae; Denham, Paul; George, Simi; Goldberg, Kenneth A.; Goldstein, Michael; Hoef, Brian; Hudyma, Russ; Jones, Gideon; Koh, Chawon; La Fontaine, Bruno; McClinton, Brittany; Miyakawa, Ryan; Montgomery, Warren; Roller, John; Wallow, Tom; Wurm, Stefan

    2009-02-16

    Microfield exposure tools (METs) continue to playa dominant role in the development of extreme ultraviolet (EUV) resists. One of these tools is the SEMATECH Berkeley 0.3-NA MET operating as a SEMATECH resist and mask test center. Here we present an update summarizing the latest resist test and characterization results. The relatively small numerical aperture and limited illumination settings expected from 1st generation EUV production tools make resist resolution a critical issue even at the 32-nm node. In this presentation, sub 22 nm half pitch imaging results of EUV resists are reported. We also present contact hole printing at the 30-nm level. Although resist development has progressed relatively well in the areas of resolution and sensitivity, line-edge-roughness (LER) remains a significant concern. Here we present a summary of recent LER performance results and consider the effect of system-level contributors to the LER observed from the SEMA TECH Berkeley microfield tool.

  14. Climate Change from the Mars Exploration Rover Landing Sites: From Wet in the Noachian to Dry and Desiccating Since the Hesperian

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Grant, J. A.; Crumpler, L. S.; Greeley, R.; Arvidson, R. E.

    2005-01-01

    Mars Exploration Rover Opportunity discovered sedimentary dirty evaporites in Meridiani Planum that were deposited in salt-water playas or sabkhas in the Noachian, roughly coeval with a variety of geomorphic indicators (valley networks, degraded craters and highly eroded terrain) of a possible early warmer and wetter environment. In contrast, the cratered plains of Gusev that Spirit has traversed (exclusive of the Columbia Hills) have been dominated by impact and eolian processes and a gradation history that argues for a dry and desiccating environment since the Late Hesperian. This paper reviews the surficial geology and gradation history of the plains in Gusev crater as observed along the traverse by Spirit that supports this climate change from the two landing sites on Mars.

  15. Poisoning of Canada geese in Texas by parathion sprayed for control of Russian wheat aphid

    USGS Publications Warehouse

    Flickinger, Edward L.; Juenger, Gary; Roffe, Thomas J.; Smith, Milton R.; Irwin, Roy J.

    1991-01-01

    Approximately 200 Canada geese (Branta canadensis) died at a playa lake in the Texas Panhandle shortly after a winter wheat field in the basin adjacent to the lake was treated with parathion to control newly invading Russian wheat aphids (Diuraphis noxia). No evidence of infectious disease was diagnosed during necropsies of geese. Brain ChE activities were depressed up to 77% below normal. Parathion residues in GI tract contents of geese ranged from 4 to 34 ppm. Based on this evidence, parathion was responsible for the goose mortalities. Parathion applications to winter wheat will undoubtedly increase if parathion is applied for control of both Russian wheat aphids and greenbugs (Schizaphis graminum). Geese may potentially be exposed to widespread applications of parathion from fall to spring, essentially their entire wintering period.

  16. Hydrology of the Bonneville Salt Flats, northwestern Utah, and simulation of ground-water flow and solute transport in the shallow-brine aquifer

    USGS Publications Warehouse

    Mason, James L.; Kipp, Kenneth L.

    1998-01-01

    This report describes the hydrologic system of the Bonneville Salt Flats with emphasis on the mechanisms of solute transport. Variable-density, three-dimensional computer simulations of the near-surface part of the ground-water system were done to quantify both the transport of salt dissolved in subsurface brine that leaves the salt-crust area and the salt dissolved and precipitated on the land surface. The study was designed to define the hydrology of the brine ground-water system and the natural and anthropogenic processes causing salt loss, and where feasible, to quantify these processes. Specific areas of study include the transport of salt in solution by ground-water flow and the transport of salt in solution by wind-driven ponds and the subsequent salt precipitation on the surface of the playa upon evaporation or seepage into the subsurface. In addition, hydraulic and chemical changes in the hydrologic system since previous studies were documented.

  17. Constellation Program Electrical Ground Support Equipment Research and Development

    NASA Technical Reports Server (NTRS)

    McCoy, Keegan S.

    2010-01-01

    At the Kennedy Space Center, I engaged in the research and development of electrical ground support equipment for NASA's Constellation Program. Timing characteristics playa crucial role in ground support communications. Latency and jitter are two problems that must be understood so that communications are timely and consistent within the Kennedy Ground Control System (KGCS). I conducted latency and jitter tests using Alien-Bradley programmable logic controllers (PLCs) so that these two intrinsic network properties can be reduced. Time stamping and clock synchronization also play significant roles in launch processing and operations. Using RSLogix 5000 project files and Wireshark network protocol analyzing software, I verified master/slave PLC Ethernet module clock synchronization, master/slave IEEE 1588 communications, and time stamping capabilities. All of the timing and synchronization test results are useful in assessing the current KGCS operational level and determining improvements for the future.

  18. Avian cholera in the central and Mississippi flyways 1979-80

    USGS Publications Warehouse

    Brand, C.J.

    1984-01-01

    Waterfowl mortality from avian cholera during July 1979-May 1980 was widespread in the Central and Mississippi flyways, occurring in a wide variety of species and locations from nesting grounds of snow geese (Chen caerulescens) on Hudson Bay south to waterfowl wintering areas on the Texas coast and playa lakes region. Mortality estimates at the various sites ranged from several birds to over 72,000. The chronological and geographic occurrence of outbreaks corresponded closely to waterfowl migrations from infected sites, suggesting that waterfowl served to distribute avian cholera along migration routes. Recurrent outbreaks at several locations suggest that these sites have become enzootic for this disease. The magnitude of avian cholera mortality and its geographic spread during 1979-80 underscores the need to address management of this disease on an intra- and inter-flyway basis.

  19. Metaviromics of Namib Desert Salt Pans: A Novel Lineage of Haloarchaeal Salterproviruses and a Rich Source of ssDNA Viruses.

    PubMed

    Adriaenssens, Evelien M; van Zyl, Leonardo Joaquim; Cowan, Don A; Trindade, Marla I

    2016-01-08

    Viral communities of two different salt pans located in the Namib Desert, Hosabes and Eisfeld, were investigated using a combination of multiple displacement amplification of metaviromic DNA and deep sequencing, and provided comprehensive sequence data on both ssDNA and dsDNA viral community structures. Read and contig annotations through online pipelines showed that the salt pans harbored largely unknown viral communities. Through network analysis, we were able to assign a large portion of the unknown reads to a diverse group of ssDNA viruses. Contigs belonging to the subfamily Gokushovirinae were common in both environmental datasets. Analysis of haloarchaeal virus contigs revealed the presence of three contigs distantly related with His1, indicating a possible new lineage of salterproviruses in the Hosabes playa. Based on viral richness and read mapping analyses, the salt pan metaviromes were novel and most closely related to each other while showing a low degree of overlap with other environmental viromes.

  20. An exploitation of coregistered SIR-A, Seasat and Landsat images

    NASA Technical Reports Server (NTRS)

    Rebillard, P.; Nguyen, T. P.

    1983-01-01

    Multispectral registration and classification of SIR-A, Seasat SAR, and Landsat MSS data is presented over two playas located in the northeastern Algerian Sahara. A supervised classification was made over six classes: salt, palm trees, dunes, limestones, gypsum and sand. The best classification is obtained by using all of the data. The images using radar only misclassify trees and salt, limestone and dunes, gypsum and dunes. Landsat only gives a good map but lacks the roughness information contained in the radar data. The Landsat/SIR-A combination gives a better classification than the Landsat/Seasat combination. Density number histograms computed within several classes on the Seasat and SIR-A data show the misclassification is mainly due to the Seasat data.

  1. Cultural resources: Deaf Smith and Swisher County locations, Palo Duro Basin, Texas

    SciTech Connect

    Not Available

    1984-12-01

    Cultural resources are prehistoric and historic sites, including archeological and paleontological sites, that are important to a group of people. They are protected by both federal and state legislation. In the area covered by the Deaf Smith and Swisher County locations, four stages of cultural development have been identified: Paleo-Indian, Archaic, Ceramic (Neo-Indian or Neo-American), and Historic. Areas where undiscovered cultural resources are most likely to be found include sources of water, playa lakes, and historic trails. Because extensive surveying has not been done in either location, the number of identified sites is low. However, the potential for finding undiscovered sites is high for significant parts of both locations.

  2. Visual assessments for Swisher County and Deaf Smith County locations, Palo Duro Basin, Texas

    SciTech Connect

    Not Available

    1984-12-01

    The area of the Swisher and Deaf Smith County locations is characterized by vast open spaces with limited vertical relief and vegetative cover. The stream valleys and areas around the playa lakes provide the only significant topographical relief in either location, and the areas in range vegetation provide the only major contrast to the dominant land cover of agricultural crops. Tree stands occur almost exclusively in association with orchards, country clubs, farmsteads, and urban areas. Because of climatic conditions in the region, there are few permanent water bodies in either location. Grain elevators, farmsteads, and other cultural modifications (roads, utility lines, fence rows, etc.) are scattered throughout both locations, but they constitute a very small portion of the visible landscape. These features help provide scale in the landscape and also serve as visual landmarks.

  3. Technical procedures for water resources: Volume 3, Environmental Field Program, Deaf Smith County Site, Texas: Final draft

    SciTech Connect

    Not Available

    1987-08-01

    To ensure that the environmental field program comprehensively addresses the issues and requirements of the project, a site study plan (SSP) has been prepared for Water Resources (ONWI, 1987). This technical procedure (TP) has been developed to implement the field program described in the Water Resources Site Study Plan. This procedure provides the general method for the field collection of water and sediment samples from playa lakes using an Alpha horizontal type sampler or equivalent or a peristaltic pump for water and a KB-coring devise or ponar grab for sediments. The samples will be preserved and then shipped to a laboratory for analysis. The water quality and sediment samples will be collected as part of the surface-water quality field study described in the Site Plan for Water Resources. 15 refs., 5 figs., 3 tabs.

  4. Site Study Plan for laboratory soil mechanics, Deaf Smith County site, Texas: Revision 1

    SciTech Connect

    Not Available

    1987-12-01

    This Site Study Plan for laboratory soil mechanics describes the laboratory testing to be conducted on soil samples collected as part of the characterization of the Deaf Smith County site, Texas. This study provides for measurements of index, mechanical, thermal, hydrologic, chemical, and mineral properties of soils from boring throughout the site. Samples will be taken from Playa Borings/Trenching, Transportation/Utilities Foundation Borings, Repository Surface Facilities Design Foundation Borings, and Exploratory Shaft Facilities Design Foundation Borings. Data from the laboratory tests will be used for soil strata characterization, design of foundations for surface structures, design of transportation facilities and utility structures, design of impoundments, design of shaft lining, design of the shaft freeze wall, shaft permitting, performance assessment calculations, and other program requirements. A tentative testing schedule and milestone log are given. A quality assurance program will be utilized to assure that activities affecting quality are performed correctly and that appropriate documentation is maintained. 18 refs., 6 figs., 3 tabs.

  5. The Impact of Horizontal and Temporal Resolution on Convection and Precipitation with High-Resolution GEOS-5

    NASA Technical Reports Server (NTRS)

    Putman, William P.

    2012-01-01

    Using a high-resolution non-hydrostatic version of GEOS-5 with the cubed-sphere finite-volume dynamical core, the impact of spatial and temporal resolution on cloud properties will be evaluated. There are indications from examining convective cluster development in high resolution GEOS-5 forecasts that the temporal resolution within the model may playas significant a role as horizontal resolution. Comparing modeled convective cloud clusters versus satellite observations of brightness temperature, we have found that improved. temporal resolution in GEOS-S accounts for a significant portion of the improvements in the statistical distribution of convective cloud clusters. Using satellite simulators in GEOS-S we will compare the cloud optical properties of GEOS-S at various spatial and temporal resolutions with those observed from MODIS. The potential impact of these results on tropical cyclone formation and intensity will be examined as well.

  6. Does localized recharge occur at a discharge area within the ground-water flow system of Yucca Mountain, Nevada?

    SciTech Connect

    Czarnecki, J.B.; Kroitoru, L.; Ronen, D. |; Magaritz, M.

    1992-10-01

    Studies done in 1984, at a central site on Franklin Lake playa (also known as Alkali Flat, a major discharge area of the ground-water flow system that includes Yucca Mountain, Nevada, the potential site of a high-level nuclear-waste repository) yield limited hydraulic-head and hydrochemical data from a 3-piezometer nest which indicated a slightly downward hydraulic gradient ({minus}0.02) and decreasing concentration of dissolved solids with increasing depth. Hydraulic-head measurements in June, 1989 made at the piezometer nest showed a substantially larger downward gradient ({minus}0.10) and a 0. 83{minus}meter higher water level in the shallowest piezometer (3.29 meters deep), indicating the possibility of localized recharge. during the period of September-November, 1989, a multilevel sampler was used to obtain detailed hydrochemical profiles of the uppermost 1. 5 m of the saturated zone.

  7. A Marine Origin for the Meridiani Planum Landing Site?

    NASA Technical Reports Server (NTRS)

    Parker, T. J.; Haldemann, A. F.

    2005-01-01

    The Opportunity instruments have provided compelling evidence that the sulfate-rich chemical and siliciclastic sediments at the Meridiani Planum landing site were deposited in shallow water. The local paleo-environment is most often characterized as a broad, shallow sea or large playa, with surface conditions cycling between wet and dry episodes, interbedding evaporates with eolian fine sediments [e.g., 1,2]. This particular working hypothesis is reasonable, considering the area characterized by the rover s mobility. An alternative, marine origin will be considered here, a working hypothesis that we feel provides a better fit to the local-scale results identified by Opportunity, and the regional-scale characteristics of Meridiani Planum provided by data from orbiting spacecraft, when considered together.

  8. Landsat radiometric cross-calibration: extended analysis of tandem image data sets

    NASA Astrophysics Data System (ADS)

    Teillet, P. M.; Markham, Brian L.; Irish, Richard R.

    2005-10-01

    The paper presents the results of an extended analysis of image data sets acquired during the tandem-orbit configuration in 1999 for the purposes of radiometric cross-calibration of the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) and Landsat-5 Thematic Mapper (TM) sensors. Earlier work focused on the tandem pair for the Railroad Valley Playa, Nevada (RVPN) site to tie down the Landsat-5 TM calibration based on the more accurate Landsat-7 ETM+ calibration. This paper describes new results based on as many as eight tandem image pairs. The additional tandem images are of vegetated areas for which little or no ground reference data were available. Increasing the number of tandem pairs yielded results for the Landsat 5 TM gain coefficients within approximately +/- 1 % of the RVPN-based results in spectral bands 1, 2, 3 and 7, and within -2 % and -4 % of the RVPN-based results for spectral bands 4 and 5, respectively.

  9. Mapping composition in dust-producing regions: Extending geochemical measurements over large scales with remote sensing

    NASA Astrophysics Data System (ADS)

    Tollerud, H. J.; Elmore, A. J.; Fantle, M. S.

    2009-12-01

    Dust is a critical, yet understudied, component of geochemical cycles. Dust inputs to the ocean have been deemed especially significant in the iron cycle, for instance, since dust stimulates natural iron fertilization and thus potentially affects climate. Dust may also be important to the cycles of other elements, such as calcium (Ca). To determine the importance of dust relative to other geochemical inputs, some estimate must be made of the mass flux of Ca from dust-producing regions. However, understanding the spatial distribution of Ca within terrain known to generate dust has been problematic. Remote sensing may offer a critical perspective with measurement at landscape scales instead of extrapolation from a few point measurements, allowing for investigation closer to the scale at which dust is produced. This study investigates the elemental geochemistry of surface sediments and the distribution of non-silicate bound Ca in a large playa system (Black Rock Desert) in northwestern Nevada (USA). We used satellite-derived hyperspectral data, field-collected ground spectra, surface sediment samples, and Synthetic Aperture Radar (SAR) in our analysis. We collected approximately 50 samples and their spectra from the Black Rock Desert in July/August 2007. We measured the bulk and soluble Ca by ICP-OES and mineralogy by x-ray diffraction (XRD). Assuming all Ca in weak HCl (0.5 N) leaches is derived from calcite, we found that calcite concentrations in a subset of collected samples range from 5 to 15 wt. %. Acid-soluble calcite, which was generally 90 to 100 mol % of the total Ca in sediments (determined by lithium metaborate fusion), correlates well with the relative abundance of calcite determined by XRD analyses. Using hyperspectral measurements of surface reflectance, we found that acid soluble Ca concentration is correlated with the depth of a calcite absorption feature at 2335 nm. We then mapped this depth in satellite hyperspectral data from the Hyperion

  10. Ecological and Taxonomic Features of Actinomycetal Complexes in Soils of the Lake Elton Basin

    NASA Astrophysics Data System (ADS)

    Zenova, G. M.; Dubrova, M. S.; Kuznetsova, A. I.; Gracheva, T. A.; Manucharova, N. A.; Zvyagintsev, D. G.

    2016-02-01

    In the sor (playa) solonchaks of chloride and sulfate-chloride salinity (the content of readily soluble salts is 0.9-1.0%) in the delta of the Khara River discharging into Lake Elton, the number of mycelial actinobacteria (actinomycetes) is low ((2-3) × 103 CFU/g of soil). At a distance from the water's edge, these soils are substituted for the light chestnut ones, for which an elevated number of actinomycetes (an order of magnitude higher than in the sor solonchaks) and a wider generic spectrum are characteristic. The actinomycetal complex is included the Streptomyces and Micromonospora genera, whereas in the sor solonchaks around the lake, representatives of Micromonospora were not found.

  11. Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in the Vermejo Project area and the Maxwell National Wildlife Refuge, Colfax County, northeastern New Mexico, 1993

    USGS Publications Warehouse

    Bartolino, J.R.; Garrabrant, L.A.; Wilson, Mark; Lusk, J.D.

    1996-01-01

    invertebrates. Concentrations of other elements were below their respective toxicity levels. Plants, invertebrates, fish, and fish fillets were collected and analyzed. These analyses were compared to diagnostic criteria and to each other to determine the extent of bioaccumulation of trace elements. Plants contained larger dry weight concentrations of aluminum, arsenic, boron, chromium, iron, lead, magnesium, manganese, nickel, and vanadium than invertebrates and fish. Adult brine flies, gathered from playas, contained larger geometric mean dry weight concentrations of boron, magnesium, and selenium than other invertebrates. Of all samples collected, the largest mercury concentrations were found in fish fillets, although these concentrations were below levels of concern. Mercury and selenium bioaccumulation was evident in various habitats of the study area. Biological samples from Natural playa, an endemic wetland, and Half playa, a playa that receives additional water through seepage and irrigation delivery canals, generally had elevated concentrations of boron, iron, magnesium, and selenium than samples from reservoir and river sites. Selenium concentrations were lowest in biota from the two reservoir sites, although a wetland immediately downstream from the dam impounding Lake No. 13 (created by seepage from the reservoir) had elevated concentrations of selenium in biota. The geometric mean selenium concentration of whole-fish samples, except those from Lakes No. 13 and No. 14, exceeded the 5-mg/g dry weight selenium concentration that demarcates the approximate lower limit of the threshold range of concentrations that have been associated with adverse effects on piscine reproduction. Biota collected on and in the area around Maxwell National Wildlife Refuge contained concentrations of selenium that are in the low

  12. Mojave remote sensing field experiment

    NASA Technical Reports Server (NTRS)

    Arvidson, Raymond E.; Petroy, S. B.; Plaut, J. J.; Shepard, Michael K.; Evans, D.; Farr, T.; Greeley, Ronald; Gaddis, L.; Lancaster, N.

    1991-01-01

    The Mojave Remote Sensing Field Experiment (MFE), conducted in June 1988, involved acquisition of Thermal Infrared Multispectral Scanner (TIMS); C, L, and P-band polarimetric radar (AIRSAR) data; and simultaneous field observations at the Pisgah and Cima volcanic fields, and Lavic and Silver Lake Playas, Mojave Desert, California. A LANDSAT Thematic Mapper (TM) scene is also included in the MFE archive. TM-based reflectance and TIMS-based emissivity surface spectra were extracted for selected surfaces. Radiative transfer procedures were used to model the atmosphere and surface simultaneously, with the constraint that the spectra must be consistent with field-based spectral observations. AIRSAR data were calibrated to backscatter cross sections using corner reflectors deployed at target sites. Analyses of MFE data focus on extraction of reflectance, emissivity, and cross section for lava flows of various ages and degradation states. Results have relevance for the evolution of volcanic plains on Venus and Mars.

  13. Using remote sensing and GIS techniques to estimate discharge and recharge. fluxes for the Death Valley regional groundwater flow system, USA

    USGS Publications Warehouse

    D'Agnese, F. A.; Faunt, C.C.; Keith, Turner A.

    1996-01-01

    The recharge and discharge components of the Death Valley regional groundwater flow system were defined by remote sensing and GIS techniques that integrated disparate data types to develop a spatially complex representation of near-surface hydrological processes. Image classification methods were applied to multispectral satellite data to produce a vegetation map. This map provided a basis for subsequent evapotranspiration and infiltration estimations. The vegetation map was combined with ancillary data in a GIS to delineate different types of wetlands, phreatophytes and wet playa areas. Existing evapotranspiration-rate estimates were then used to calculate discharge volumes for these areas. A previously used empirical method of groundwater recharge estimation was modified by GIS methods to incorporate data describing soil-moisture conditions, and a recharge potential map was produced. These discharge and recharge maps were readily converted to data arrays for numerical modelling codes. Inverse parameter estimation techniques also used these data to evaluate the reliability and sensitivity of estimated values.

  14. [Demography of the snail Plicopurpura pansa (Neotaenioglossa: Muricidae) and constitution of the associated mollusk community, in Guerrero, Mexico].

    PubMed

    Flores-Garza, Rafael; Flores-Rodriguez, Pedro; García-Ibáñez, Sergio; Valdés-González, Arcadio

    2007-01-01

    We quarterly sampled the molluskan community of Playa Ventura, Guerrero, Mexico. Sample size (20 m2 in lm2 units) was determined by the spatial distribution pattern of Plicopurpura pansa using a negative binomial distribution. The density of the P. pansa was 5.19 snails/m2 and the sex ratio near 1:1. The average size was 20.10 mm (most females were 10.5 to 27.0 mm; most males 12.0 to 27.0 mm). Density was high and small sized dominated. Mean size varied with time. General mean weight was 1.79 g. Females weight varied more, maybe because of the reproductive cycle. Recruits were collected in five samplings. Most copulation activity was in March of 2001. The associated community includes 26 species of Gastropoda, five ofBivalvia and one of Polyplacophora, Brachidontes semilaevis being dominant. PMID:19086391

  15. Avian cholera in common crows, Corvus brachyrhynchos, from the central Texas panhandle.

    PubMed

    Taylor, T T; Pence, D B

    1981-10-01

    An epornitic of avian cholera involving approximately 150 birds is described from a flock of common crows, Corvus brachyrhynchos, on a single playa lake utilized as a roost in Castro County, Texas, during early spring of 1980. There was a concomitant epornitic of avian cholera involving several hundred ducks and geese of several species on adjacent lakes in he same area. Crows scavenged extensively on waterfowl carcasses. Gross and histopathologic lesions in waterfowl were typical of acute avian cholera. Crows had a more chronic form of the disease, especially neurological involvement with the most common lesion consisting of a hemorrhagic meningitis. Other endemic species from which Pasteurella multocida was isolated included the short-eared owl, Asio flammeus, and cottontail rabbit, Silvilagus sp. The role of crows in the dissemination and maintenance of avian cholera is discussed.

  16. Equation of state for shock compression of distended solids

    NASA Astrophysics Data System (ADS)

    Grady, Dennis; Fenton, Gregg; Vogler, Tracy

    2014-05-01

    Shock Hugoniot data for full-density and porous compounds of boron carbide, silicon dioxide, tantalum pentoxide, uranium dioxide and playa alluvium are investigated for the purpose of equation-of-state representation of intense shock compression. Complications of multivalued Hugoniot behavior characteristic of highly distended solids are addressed through the application of enthalpy-based equations of state of the form originally proposed by Rice and Walsh in the late 1950's. Additive measures of cold and thermal pressure intrinsic to the Mie-Gruneisen EOS framework is replaced by isobaric additive functions of the cold and thermal specific volume components in the enthalpy-based formulation. Additionally, experimental evidence reveals enhancement of shock-induced phase transformation on the Hugoniot with increasing levels of initial distension for silicon dioxide, uranium dioxide and possibly boron carbide. Methods for addressing this experimentally observed feature of the shock compression are incorporated into the EOS model.

  17. Equation of State for Shock Compression of High Distension Solids

    NASA Astrophysics Data System (ADS)

    Grady, Dennis

    2013-06-01

    Shock Hugoniot data for full-density and porous compounds of boron carbide, silicon dioxide, tantalum pentoxide, uranium dioxide and playa alluvium are investigated for the purpose of equation-of-state representation of intense shock compression. Complications of multivalued Hugoniot behavior characteristic of highly distended solids are addressed through the application of enthalpy-based equations of state of the form originally proposed by Rice and Walsh in the late 1950's. Additivity of cold and thermal pressure intrinsic to the Mie-Gruneisen EOS framework is replaced by isobaric additive functions of the cold and thermal specific volume components in the enthalpy-based formulation. Additionally, experimental evidence supports acceleration of shock-induced phase transformation on the Hugoniot with increasing levels of initial distention for silicon dioxide, uranium dioxide and possibly boron carbide. Methods for addressing this experimentally observed facet of the shock compression are introduced into the EOS model.

  18. Correlation of foreshocks and aftershocks and asperities

    NASA Astrophysics Data System (ADS)

    Hsu, Vindell; Helsley, Charles E.; Berg, Eduard; Novelo-Casanova, David A.

    1984-11-01

    A close correlation in spatial distribution of local seismic activity and energy release patterns before and after the 1979 Petatlan, Mexico earthquake suggests heterogeneity within the fault plane of this major low-angle thrust event associated with subduction along the Middle America Trench. A simple two-asperity model is proposed to account for the complexity. Foreshocks and aftershocks of the neighboring 1981 Playa Azul earthquake showed a similar pattern. As both events occurred at the junction of the Orozco Fracture Zone and the Middle America Trench, we speculate that the observed complex fault plane is caused by subduction of the rugged ocean floor of the Orozco Fracture Zone. Short-term precursory seismicity prior to the Petatlan earthquake can be explained by using the asperity model and migration of a slip front from the south-east to the north-west across the main shock source region.

  19. In Brief: Anoxic ``dead zones'' in oceans; Some Mars rocks likely formed in water

    NASA Astrophysics Data System (ADS)

    Showstack, Randy; Jacobs, Judith

    2004-04-01

    The number of oxygen-starved ``dead zones'' in the world's oceans and seas is rising, according to a report of the United Nations Environment Programme published 29 March-the result of excessive nutrients, mainly nitrogen, from the use of synthetic fertilizers in agriculture, as well as vehicle and factory air emissions. NASA's Opportunity Rover has found that some rocks on Mars probably formed as deposits in a shallow salt flat, or playa, rover science team members announced on 23 March. When scientists announced on 2 March that they had found strong evidence that a rock outcrop in Mars' Meridiana Planum region once was a wet and habitable environment, they had still been uncertain about whether the rocks had been laid down in liquid water. (See Eos, 16 March 2004.)

  20. Metaviromics of Namib Desert Salt Pans: A Novel Lineage of Haloarchaeal Salterproviruses and a Rich Source of ssDNA Viruses

    PubMed Central

    Adriaenssens, Evelien M.; van Zyl, Leonardo Joaquim; Cowan, Don A.; Trindade, Marla I.

    2016-01-01

    Viral communities of two different salt pans located in the Namib Desert, Hosabes and Eisfeld, were investigated using a combination of multiple displacement amplification of metaviromic DNA and deep sequencing, and provided comprehensive sequence data on both ssDNA and dsDNA viral community structures. Read and contig annotations through online pipelines showed that the salt pans harbored largely unknown viral communities. Through network analysis, we were able to assign a large portion of the unknown reads to a diverse group of ssDNA viruses. Contigs belonging to the subfamily Gokushovirinae were common in both environmental datasets. Analysis of haloarchaeal virus contigs revealed the presence of three contigs distantly related with His1, indicating a possible new lineage of salterproviruses in the Hosabes playa. Based on viral richness and read mapping analyses, the salt pan metaviromes were novel and most closely related to each other while showing a low degree of overlap with other environmental viromes. PMID:26761024

  1. Application of the ERTS system to the study of Wyoming resources with emphasis on the use of basic data products

    NASA Technical Reports Server (NTRS)

    Houston, R. S.; Marrs, R. W.; Breckenridge, R. M.; Blackstone, D. L., Jr.

    1974-01-01

    Many potential users of ERTS data products and other aircraft and satellite imagery are limited to visual methods of analyses of these products. Illustrations are presented from Wyoming studies that have employed these standard data products for a variety of geologic and related studies. Possible economic applications of these studies are summarized. Studies include regional geologic mapping for updating and correcting existing maps and to supplement incomplete regional mapping; illustrations of the value of seasonal images in geologic mapping; specialized mapping of such features as sand dunes, playa lakes, lineaments, glacial features, regional facies changes, and their possible economic value; and multilevel sensing as an aid in mineral exploration. Examples of cooperative studies involving botanists, plant scientists, and geologists for the preparation of maps of surface resources that can be used by planners and for environmental impact studies are given.

  2. Mycelial actinobacteria in salt-affected soils of arid territories of Ukraine and Russia

    NASA Astrophysics Data System (ADS)

    Grishko, V. N.; Syshchikova, O. V.; Zenova, G. M.; Kozhevin, P. A.; Dubrova, M. S.; Lubsanova, D. A.; Chernov, I. Yu.

    2015-01-01

    A high population density (up to hundreds of thousands or millions CFU/g soil) of mycelial bacteria (actinomycetes) is determined in salt-affected soils of arid territories of Ukraine, Russia, and Turkmenistan. Of all the studied soils, the lowest amounts of actinomycetes (thousands and tens of thousands CFU/g soil) are isolated from sor (playa) and soda solonchaks developed on the bottoms of drying salt lakes in Buryatia and in the Amu Darya Delta. Actinomycetes of the Streptomyces, Micromonospora, and Nocardiopsis genera were recorded in the studied soils. It is found that conditions of preincubation greatly affect the activity of substrate consumption by the cultures of actinomycetes. This could be attributed to changes in the metabolism of actinomycetes as a mechanism of their adaptation to the increased osmotic pressure of the medium. The alkali tolerance of halotolerant actinomycetes isolated from the salt-affected soils is experimentally proved.

  3. Metaviromics of Namib Desert Salt Pans: A Novel Lineage of Haloarchaeal Salterproviruses and a Rich Source of ssDNA Viruses.

    PubMed

    Adriaenssens, Evelien M; van Zyl, Leonardo Joaquim; Cowan, Don A; Trindade, Marla I

    2016-01-01

    Viral communities of two different salt pans located in the Namib Desert, Hosabes and Eisfeld, were investigated using a combination of multiple displacement amplification of metaviromic DNA and deep sequencing, and provided comprehensive sequence data on both ssDNA and dsDNA viral community structures. Read and contig annotations through online pipelines showed that the salt pans harbored largely unknown viral communities. Through network analysis, we were able to assign a large portion of the unknown reads to a diverse group of ssDNA viruses. Contigs belonging to the subfamily Gokushovirinae were common in both environmental datasets. Analysis of haloarchaeal virus contigs revealed the presence of three contigs distantly related with His1, indicating a possible new lineage of salterproviruses in the Hosabes playa. Based on viral richness and read mapping analyses, the salt pan metaviromes were novel and most closely related to each other while showing a low degree of overlap with other environmental viromes. PMID:26761024

  4. Microelements in solonchaks of the western Trans-Baikal region

    NASA Astrophysics Data System (ADS)

    Sosorova, S. B.; Merkusheva, M. G.; Boloneva, L. N.; Baldanova, A. L.; Ubugunov, L. L.

    2016-04-01

    Distribution patterns of microelements (Mn, Zn, Ni, Cu, Cr, Co, Pb, and Cd) in solonchaks of the western Trans-Baikal region were studied. It was found that their concentrations in typical solonchaks of haloxerophytic steppe differed from those in solonchaks of moistened habitats (playa, gleyed, and dark solonchaks) because of the differences in their landscape positions and ecological conditions. A general rise in the contents of the microelements was observed from the northeast to the southwest in agreement with changes in the parent materials. Different degrees of correlation of the contents of the microelements and their exchangeable forms with the contents of soluble salts, humus, and physical clay in the soils and the soil reaction were found. The average and extreme concentrations of the microelements were determined. The studied typical solonchaks differed from the zonal chestnut soils in the higher contents of Co, Cr, and Cd; whereas solonchaks of moistened habitats were enriched in Mn, Co, and Cd.

  5. Tectonic and climatic controls on fan systems: The Kohrud mountain belt, Central Iran

    NASA Astrophysics Data System (ADS)

    Jones, Stuart J.; Arzani, Nasser; Allen, Mark B.

    2014-04-01

    Late Pleistocene to Holocene fans of the Kohrud mountain belt (Central Iran) illustrate the problems of differentiating tectonic and climatic drivers for the sedimentary signatures of alluvial fan successions. It is widely recognised that tectonic processes create the topography that causes fan development. The existence and position of fans along the Kohrud mountain belt, NE of Esfahan, are controlled by faulting along the Qom-Zefreh fault system and associated fault zones. These faults display moderate amounts of historical and instrumental seismicity, and so may be considered to be tectonically active. However, fluvial systems on the fans are currently incising in response to low Gavkhoni playa lake levels since the mid-Holocene, producing incised gullies on the fans up to 30 m deep. These gullies expose an interdigitation of lake deposits (dominated by fine-grained silts and clays with evaporites) and coarse gravels that characterise the alluvial fan sediments. The boundaries of each facies are mostly sharp, with fan sediments superimposed on lake sediments with little to no evidence of reworking. In turn, anhydrite-glauberite, mirabilite and halite crusts drape over the gravels, recording a rapid return to still water, shallow ephemeral saline lake sedimentation. Neither transition can be explained by adjustment of the hinterland drainage system after tectonic uplift. The potential influence in Central Iran of enhanced monsoons, the northward drift of the Intertopical Convergence Zone (ITCZ) and Mediterranean climates for the early Holocene (~ 6-10 ka) point to episodic rainfall (during winter months) associated with discrete high magnitude floods on the fan surfaces. The fan sediments were deposited under the general influence of a highstand playa lake whose level was fluctuating in response to climate. This study demonstrates that although tectonism can induce fan development, it is the sensitive balance between aridity and humidity resulting from changes in

  6. Regional and climatic controls on seasonal dust deposition in the southwestern U.S.

    USGS Publications Warehouse

    Reheis, M.C.; Urban, F.E.

    2011-01-01

    Vertical dust deposition rates (dust flux) are a complex response to the interaction of seasonal precipitation, wind, changes in plant cover and land use, dust source type, and local vs. distant dust emission in the southwestern U.S. Seasonal dust flux in the Mojave-southern Great Basin (MSGB) deserts, measured from 1999 to 2008, is similar in summer-fall and winter-spring, and antecedent precipitation tends to suppress dust flux in winter-spring. In contrast, dust flux in the eastern Colorado Plateau (ECP) region is much larger in summer-fall than in winter-spring, and twice as large as in the MSGB. ECP dust is related to wind speed, and in the winter-spring to antecedent moisture. Higher summer dust flux in the ECP is likely due to gustier winds and runoff during monsoonal storms when temperature is also higher. Source types in the MSGB and land use in the ECP have important effects on seasonal dust flux. In the MSGB, wet playas produce salt-rich dust during wetter seasons, whereas antecedent and current moisture suppress dust emission from alluvial and dry-playa sources during winter-spring. In the ECP under drought conditions, dust flux at a grazed-and-plowed site increased greatly, and also increased at three annualized, previously grazed sites. Dust fluxes remained relatively consistent at ungrazed and currently grazed sites that have maintained perennial vegetation cover. Under predicted scenarios of future climate change, these results suggest that an increase in summer storms may increase dust flux in both areas, but resultant effects will depend on source type, land use, and vegetation cover. ?? 2011.

  7. Ancient sedimentary structures in the <3.7 Ga Gillespie Lake Member, Mars, that resemble macroscopic morphology, spatial associations, and temporal succession in terrestrial microbialites.

    PubMed

    Noffke, Nora

    2015-02-01

    Sandstone beds of the <3.7 Ga Gillespie Lake Member on Mars have been interpreted as evidence of an ancient playa lake environment. On Earth, such environments have been sites of colonization by microbial mats from the early Archean to the present time. Terrestrial microbial mats in playa lake environments form microbialites known as microbially induced sedimentary structures (MISS). On Mars, three lithofacies of the Gillespie Lake Member sandstone display centimeter- to meter-scale structures similar in macroscopic morphology to terrestrial MISS that include "erosional remnants and pockets," "mat chips," "roll-ups," "desiccation cracks," and "gas domes." The microbially induced sedimentary-like structures identified in Curiosity rover mission images do not have a random distribution. Rather, they were found to be arranged in spatial associations and temporal successions that indicate they changed over time. On Earth, if such MISS occurred with this type of spatial association and temporal succession, they would be interpreted as having recorded the growth of a microbially dominated ecosystem that thrived in pools that later dried completely: erosional pockets, mat chips, and roll-ups resulted from water eroding an ancient microbial mat-covered sedimentary surface; during the course of subsequent water recess, channels would have cut deep into the microbial mats, leaving erosional remnants behind; desiccation cracks and gas domes would have occurred during a final period of subaerial exposure of the microbial mats. In this paper, the similarities of the macroscopic morphologies, spatial associations, and temporal succession of sedimentary structures on Mars to MISS preserved on Earth has led to the following hypothesis: The sedimentary structures in the <3.7 Ga Gillespie Lake Member on Mars are ancient MISS produced by interactions between microbial mats and their environment. Proposed here is a strategy for detecting, identifying, confirming, and differentiating

  8. Depositional setting of the Upper Jurassic Hith Anhydrite of the Arabian Gulf: An analog to holocene evaporites of the United Arab Emirates and Lake MacLeod of Western Australia

    SciTech Connect

    Alsharhan, A.S. ); Kendall, C.G.St.C. )

    1994-07-01

    The Upper Jurassic Hith Anhydrite is a major hydrocarbon seal in the Arabian Gulf region. Outcrops, core samples from the subsurface, and the literature indicate that the Hith Formation is composed mainly of anhydrite. In most locations where a section of the Hith Formation has been measured, this unit contains less than 20% carbonate much of which is in the form of thin laminations. This lack of carbonate, locally thick layers of salt, and the predominance of anhydrite favor a playa for the setting in which this sediment was accumulated. In fact, much of the Hith has the sedimentary characteristics of the Holocene Lake MacLeod playa of Western Australia, which is dominated by layers of gypsum and halite (what little carbonate that occurs is found in layers at the base of the section). Locally the Hith appears to have accumulated in a sabkha setting, particularly toward central Abu Dhabi where it pinches out into shallow-water, and peritidal carbonate. This sabkha setting is indicated by the interbedded relationship of the Hith anhydrites with these carbonates and the local predominance of horizontally flattened nodules and enterolithic layers of anhydrite. These latter features match some of the characteristic fabrics found in the Holocene coastal sabkhas of the United Arab Emirates. As with the local occurrences in the Hith, the Holocene sabkhas are dominated by carbonates and are divisible into a series of lateral facies belts. These are also expressed as equivalent vertical layers. Traced from seaward to landward, or from the base of the vertical sequence upward, these facies are characterized by (1) algal mat, (2) a layer of a gypsum crystal mush (3) active anhydrite replacement of gypsum (4) anhydrite with no gypsum mush, and (5) recycled eolianite and storm-washover sediments.

  9. The distribution, structure, and composition of freshwater ice deposits in Bolivian salt lakes

    USGS Publications Warehouse

    Hurlbert, S.H.; Chang, Cecily C.Y.

    1988-01-01

    Freshwater ice deposits are described from seven, high elevation (4117-4730 m), shallow (mean depth <30 cm), saline (10-103 g l-1) lakes in the southwestern corner of Bolivia. The ice deposits range to several hundred meters in length and to 7 m in height above the lake or playa surface. They are located near the lake or salar margins; some are completely surrounded by water, others by playa deposits or salt crusts. Upper surfaces and sides of the ice deposits usually are covered by 20-40 cm of white to light brown, dry sedimentary materials. Calcite is the dominant crystalline mineral in these, and amorphous materials such as diatom frustules and volcanic glass are also often abundant. Beneath the dry overburden the ice occurs primarily as horizontal lenses 1-1000 mm thick, irregularly alternating with strata of frozen sedimentary materials. Ice represents from 10 to 87% of the volume of the deposits and yields freshwater (TFR <3 g l-1) when melted. Oxygen isotope ratios for ice are similar to those for regional precipitation and shoreline seeps but much lower than those for the lakewaters. Geothermal flux is high in the region as evidenced by numerous hot springs and deep (3.0-3.5 m) sediment temperatures of 5-10??C. This flux is one cause of the present gradual wasting away of these deposits. Mean annual air temperatures for the different lakes probably are all in the range of -2 to 4??C, and mean midwinter temperatures about 5??C lower. These deposits apparently formed during colder climatic conditions by the freezing of low salinity porewaters and the building up of segregation ice lenses. ?? 1988 Dr W. Junk Publishers.

  10. Effects of artificial recharge on the Ogallala aquifer, Texas

    USGS Publications Warehouse

    Brown, Richmond Flint; Keys, W.S.

    1985-01-01

    Four recharge tests were conducted by injecting water from playa lakes through wells into the Ogallala Formation. Injection was by gravity flow and by pumping under pressure. At one site, 34-acre feet of water was injected by gravity and produced a significant increase in yield of the well. At a second site, gravity injection of only 0.58 acre-foot caused a significant decrease in permeability due to plugging by suspended sediment. At two other sites, injection by pumping 6 and 14 acre-feet respectively, resulted in discharge of water at the surface and in perching of water above the water table. Differences in success of recharge were largely due to aquifer lithology and, therefore, the type of permeability; the concentration of suspended solids in the recharge water; and the injection technique. The injection technique can be controlled and the concentration of suspended solids can be minimized by treatment, but the site for well recharge will accept water most rapidly if it is selected on the basis of a favorable geohydrologic environment. Geophysical logs were used to study the effect of aquifer lithology on recharge and to understand the movement of injected water. Temperature logs were particularly useful in tracing the movement of recharged water. Natural-gamma, gamma-gamma, and neutron logs provided important data on lithology and porosity in the aquifer and changes in porosity and water distribution resulting from recharge. Effective recharge of the Ogallala Formation, using water from playa lakes, is possible where geohydrologic conditions are favorable and the recharge system is properly constructed.

  11. Depositional processes and facies of Trail Fan sandflat: Death Valley, California

    SciTech Connect

    Malicse, A.E.; Mazzullo, J.M.; Eide, M.G. )

    1992-01-01

    A study was conducted of the alluvial fan to playa transition along Trail fan in Death Valley, California with the primary objectives of documenting sedimentary facies and textural features of so-called arid region sandflat. The study involved description of sedimentary structures along trenches and meter-deep cores, description of surficial bedforms, and collection of samples for lithological analyses. Surficial features of Trail Fan sandflat gradually change downdip as a function of texture, ground water depth, and runoff. They include: (1) tongues of mudflows; (2) shallow braided channels that taper out into mudflat or coalesced into single channels; (3) puffy grounds; and (4) flat-smooth surface of the mudflat. The sediment's texture shows a fining downdip trend except when the surface are draped by mudflows. Four facies are distinguished downdip from the alluvial fan to playa mudflat. Facies 1 consists of massive, light gray, matrix to grain supported gravel, and is interpreted as debris flow or streamflow deposit. Facies 2 consists of thin-bedded (0.6--0.06 m), tan, massive, gravelly mud and is interpreted as mudflow deposit. Facies 2 consists of repeated sequences of thick-bedded (0.15 to 0.3 m), massive to planar stratified, graveliferous sand with mud drape and is interpreted as poorly sorted sheetflood or streamflow deposit. Facies 4 consist of light gray, planar laminated, coarsening upward mud to muddy sand, and is interpreted as mudflat facies. This study shows that arid region sandflat facies is a mosaic of mudflow, debris flow, sheetflood and streamflow deposits and is more complex than previous sandflat models described.

  12. Deep burial diagenesis in Rotliegende reservoirs of the NW German Basin

    SciTech Connect

    Ramseyer, K. ); Gaupp, R.; Matter, A.

    1990-05-01

    A deeply buried Permian continental sequence forms the major gas reservoir in northwest Germany. Deposits of fluvial, eolian, and playa lake shoreline facies show the most favorable reservoir properties. Burial diagenesis is greatly influenced by primary depositional textures and eogenetic processes. However, growth of authigenic clay minerals (illite, kaolinite/dickite, chlorite) relates to changes in the chemistry and flow rate of formation waters. Three different mesogenetic fluid types can be recognized: (1) Alkaline fluids from basin center red beds: The presence of pore-lining chlorite in porous subarkoses of the playa shoreline facies probably is related to a compaction-driven influx of alkaline waters from the shaly, red bed sequences of the basin center. (2) Acidic fluids from coal-bearing Late Carboniferous sediments: An aureole of dickite/kaolinite, several hundred meters wide, is developed in Rotliegende arkosic sands where they are juxtaposed against Carboniferous horsts. In this zone, almost all feldspars were destroyed and the formation of dickite/kaolinite was followed by illite growth and bitumen impregnation. In an outer aureole with less extensive feldspar destruction, kandite minerals are not present, but a dense meshwork of well-crystallized, platy illite fills the pores. The intensity of illitization diminishes away from the Carboniferous sediments (i.e., with increasing distance of fluid migration). K-Ar ages reveal that this illite precipitated within a period when organic maturation products were expelled from the coal measures into Rotliegende sediments and when Paleozoic faults were reactivated. (3) Brines from overlying Zechstein evaporites: During late mesogenetic uplift local influxes of these brines resulted in the formation of pore-plugging carbonate and sulfate cements.

  13. Lower Cretaceous lacustrine deposits and paleosol development

    SciTech Connect

    Mantzios, C.; Vondra, C.F.

    1987-05-01

    The Little Sheep Mudstone Member of the Lower Cretaceous Cloverly Formation in the Big Horn basin, Wyoming, is predominantly a montmorillonite-rich lacustrine deposit. It is informally subdivided into lower and upper units. The lower unit is a playa-lake deposit rich in bentonite derived from the alteration of volcanic ash which had its origin to the west. Horizons of silcretes and septarian nodules are common. The latter show irregular lenticular cracks and are filled with coarse calcite and barite crystals. They formed by desiccation of a clay-gel during dry periods. Silcretes are diagenetic products that formed due to the lowering of silica solubility along with decreasing of the pH value. Desiccation cracks on the playa surface were filled with chalcedony which later underwent replacement by calcite. The upper unit is a perennial saline lake deposit similar to that accumulating in Lake Magadi of the Eastern Rift Valley, Kenya, Chert nodules covered with calcium carbonate form stratigraphically persistent horizons. This chert is the product of the magadiite-kenyaite-chert transformation of Hay. Lenticular devitrified tuffs occurring at various stratigraphic positions up to 3 m thick were deposited in depressions or swales. Locally the tuffs show evidence of mass movement. Pedogenic features in both units indicate paleosol development. Tree trunks, plant roots, burrows, clay-rich zones, and organic-rich A and more iron-rich B master horizons are recognized. These paleosols resemble modern-day Vertisols. The lower unit is not as extensive areally as the upper unit which is present throughout the Big Horn basin, indicating that extensive lakes occurred during the Early Cretaceous in the Sevier foreland basin.

  14. Geomorphic and Chemical Characteristics of Dust and Soil in the Eastern Great Basin of Utah, U.S.A.

    NASA Astrophysics Data System (ADS)

    Hahnenberger, M.; Nicoll, K.; Perry, K. D.

    2014-12-01

    This study identifies anthropogenically disturbed areas and barren playa surfaces as the two primary dust source types that repeatedly contribute to dust storm events in the eastern Great Basin of western Utah, U.S.A. Further, dust samples were found to be distinctally different elementally compared to soil samples in this region. This analysis used MODIS and USDA Land cover data to identify 4 major and 5 secondary source areas for dust in this region, which produce dust primarily during the spring and fall months and during moderate or greater drought conditions. The largest number of observed dust plumes (~ 60% of all plumes) originated from playas (ephemeral lakes) and are classified as barren land cover with a silty clay soil sediment surface. Anthropogenic disturbance is necessary to produce dust from the vegetated landscape in the eastern Great Basin, as evidenced by the new dust source active from 2008 to 2010 in the area burned by the 2007 Milford Flat Fire; this fire was the largest in Utah's history due to extensive cover of invasive cheatgrass along with drought conditions. Dust and soil samples contain similar enrichments of major soil elements, however, dust samples were significantly more enriched in Na derived from the surface salts of the Sevier Dry Lake. Trace elements were generally more enriched in dust samples and had larger enrichment values than seen in previous studies. Further, for dust and soil samples, the fine fraction (<2.5 μm) was more enriched in trace elements than the coarse fraction (2.5 to 10 μm). Composition of dust transported has influences on human health, ecosystem functioning, and biogeochemical cycling. Dust storms in the eastern Great Basin negatively impact air quality and transportation in the populated regions of Utah; this study details an improved forecasting protocol for dust storm events that will benefit transportation planning and improve public health.

  15. Occurrence of synthetic musk fragrances in effluent and non-effluent impacted environments.

    PubMed

    Chase, Darcy A; Karnjanapiboonwong, Adcharee; Fang, Yu; Cobb, George P; Morse, Audra N; Anderson, Todd A

    2012-02-01

    Synthetic musk fragrances (SMFs) are considered micropollutants and can be found in various environmental matrices near wastewater discharge areas. These emerging contaminants are often detected in wastewater at low concentrations; they are continuously present and constitute a constant exposure source. Objectives of this study were to investigate the environmental fate, transport, and transformation of SMFs. Occurrence of six polycyclic musk compounds (galaxolide, tonalide, celestolide, phantolide, traseolide, cashmeran) and two nitro musk compounds (musk xylene and musk ketone) was monitored in wastewater, various surface waters and their sediments, as well as groundwater, soil cores, and plants from a treated wastewater land application site. Specifically, samples were collected quarterly from (1) a wastewater treatment plant to determine initial concentrations in wastewater effluent, (2) a storage reservoir at a land application site to determine possible photolysis before land application, (3) soil cores to determine the amount of sorption after land application and groundwater recharge to assess lack thereof, (4) a lake system and its sediment to assess degradation, and (5) non-effluent impacted local playa lakes and sediments to assess potential sources of these compounds. All samples were analyzed using gas chromatography coupled with mass spectrometry (GC-MS). Data indicated that occurrence of SMFs in effluent-impacted environments was detectable at ng/L and ng/g concentrations, which decreased during transport throughout wastewater treatment and land application. However, unexpected concentrations, ng/L and ng/g, were also detected in playa lakes not receiving treated effluent. Additionally, soil cores from land application sites had ng/g concentrations, and SMFs were detected in plant samples at trace levels. Galaxolide and tonalide were consistently found in all environments. Information on occurrence is critical to assessing exposure to these potential

  16. Persistent leatherback turtle migrations present opportunities for conservation.

    PubMed

    Shillinger, George L; Palacios, Daniel M; Bailey, Helen; Bograd, Steven J; Swithenbank, Alan M; Gaspar, Philippe; Wallace, Bryan P; Spotila, James R; Paladino, Frank V; Piedra, Rotney; Eckert, Scott A; Block, Barbara A

    2008-07-15

    Effective transboundary conservation of highly migratory marine animals requires international management cooperation as well as clear scientific information about habitat use by these species. Populations of leatherback turtles (Dermochelys coriacea) in the eastern Pacific have declined by >90% during the past two decades, primarily due to unsustainable egg harvest and fisheries bycatch mortality. While research and conservation efforts on nesting beaches are ongoing, relatively little is known about this population of leatherbacks' oceanic habitat use and migration pathways. We present the largest multi-year (2004-2005, 2005-2006, and 2007) satellite tracking dataset (12,095 cumulative satellite tracking days) collected for leatherback turtles. Forty-six females were electronically tagged during three field seasons at Playa Grande, Costa Rica, the largest extant nesting colony in the eastern Pacific. After completing nesting, the turtles headed southward, traversing the dynamic equatorial currents with rapid, directed movements. In contrast to the highly varied dispersal patterns seen in many other sea turtle populations, leatherbacks from Playa Grande traveled within a persistent migration corridor from Costa Rica, past the equator, and into the South Pacific Gyre, a vast, low-energy, low-productivity region. We describe the predictable effects of ocean currents on a leatherback migration corridor and characterize long-distance movements by the turtles in the eastern South Pacific. These data from high seas habitats will also elucidate potential areas for mitigating fisheries bycatch interactions. These findings directly inform existing multinational conservation frameworks and provide immediate regions in the migration corridor where conservation can be implemented. We identify high seas locations for focusing future conservation efforts within the leatherback dispersal zone in the South Pacific Gyre.

  17. Technical procedures for the implementation of cultural resource site studies, Deaf Smith County, Texas: Preliminary draft

    SciTech Connect

    Not Available

    1987-09-30

    Cultural resources at the Deaf Smith County site will be identified, evaluated and managed through the implementation of studies detailed in the Site Study Plan for Cultural Resources. This technical procedure outlines the conduct of pedestrian survey and the documentation of identified cultural resources. The purpose of the field surveys is to identify and document cultural resources in the areas that will be affected by site characterization activities and to record the environmental setting of identified cultural resources. Three pedestrian surveys will cover 100 percent of the on-site and off-site project areas. Survey 1 will provide coverage of the Repository Surface Facility (RSF) area, which includes the Exploratory Shaft Facility (ESF) and two linear engineering design borehole (EDBH) seismic survey corridors. Survey 2 will provide coverage of a 39 km/sup 2/ (15 mi/sup 2/) area that includes the 23 km/sup 2/ (9 mi/sup 2/) Deaf Smith County site plus a 0.4 to 0.8 kM (1/4 to 1/2 mi) border area but excludes the area covered by Survey 1. Survey 3 will cover offsite geotechnical test areas, such as the locations of playa boreholes, deep playa wells, hydrologic tests, site foundation borings, and their access routes. The purpose of site documentation or recording is to address the project information needs for land use permits and approvals, engineering design support, and cultural resource evaluation for National Register of Historic Places eligibility. Site documentation will consist of gathering sufficient data on identified resources to complete Texas Natural Resource Information System (TNRIS). 7 refs., 3 figs.

  18. Drought modulated by North Atlantic sea surface temperatures for the last 3,000 years along the northwestern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Livsey, Daniel; Simms, Alexander R.; Hangsterfer, Alexandra; Nisbet, Robert A.; DeWitt, Regina

    2016-03-01

    In 2012 the most severe United States drought since the 1930's occurred, highlighting the need for a better understanding of the climate factors driving droughts. Spatial-temporal analysis of United States precipitation data from 1900 to 1999 indicates that the Atlantic Multidecadal Oscillation (AMO) primarily modulates drought frequency. Tree rings provide the highest resolution and most spatially distributed drought records beyond secular time-series; however, as most tree-ring records only extend to ca. 1000 years before present (BP), a new broadly distributed, quantitative, multi-millennial, proxy of past drought is needed to determine if the AMO modulated drought across North America through the late Holocene. In this study, we develop a new quantitative drought proxy from a transfer function between X-Ray Fluorescence (XRF) derived elemental data from a Texas playa and a tree-ring drought record. Using this transfer function, a 954-year tree-ring drought record was extended to ca. 3000 BP. Changes in the extended drought record correspond with timing of the Roman Climate Optimum, Medieval Warm Period, Little Ice Age, and changes in the AMO as recorded in a proxy record derived from North Atlantic ice-rafted debris. These results indicate that lacustrine-derived XRF element data can be used as a quantitative tool to reconstruct past drought records, and suggest that AMO modulated drought in southern Texas for the last 3000 years. Additional studies using XRF-derived element data as a drought proxy are needed to determine the utility of this proxy in non-playa lacustrine systems.

  19. Water-level predictions for Indian Wells Valley ground-water basin, California, 1978

    USGS Publications Warehouse

    Mallory, Michael J.

    1979-01-01

    Ground-water pumpage in Indian Wells Valley, virtually a closed basin in the Mojave Desert of southern California, has increased gradually since 1945 and presently exceeds the long-term mean annual recharge (perennial supply). In order to aid in the understanding and management of the ground-water basin, a digital ground-water model was constructed by the U.S. Geological Survey. Since the original development of this model, conditions in the basin, including areal distribution and rates of ground-water pumpage, have changed. The results of simulation for the period 1969-76 constitute a second verification of the original model. Calculated heads for 1976 agree with the observed heads, indicating a good calibration of the original model. A predictive simulation for the period 1977-2020 used pumpage values increasing from about 15,500 acre-feet per year to about 26,000 acre-feet per year. The pumpage used in this report reflects a slightly slower growth rate and a more concentrated pattern of development than that investigated when the model was originally developed. The effects of this pattern of pumpage are reflected in the water levels simulated by the model. Predicted drawdowns for 1983 are less extensive but locally more severe than those predicted earlier. The reversal of the hydraulic gradient between China Lake playa and the city of Ridgecrest, as produced by these drawdowns by the year 2020, suggests that the water-quality effects of such drawdowns should be investigated, as this could result in inferior water from the China Lake playa area flowing southward into areas of withdrawal. (Woodard-USGS)

  20. Simulation of Carbon-14 Migration Through a Thick Unsaturated Alluvial Basin Resulting from an Underground Nuclear Explosion

    NASA Astrophysics Data System (ADS)

    Martian, P.; Larentzos, J.

    2008-12-01

    Yucca Flat is one of several areas on the Nevada Test Site that was used for underground nuclear testing. Extensive testing performed in the unsaturated and saturated zones have resulted in groundwater contamination and surface subsidence craters in the vicinity of the underground test areas. Simulation of multiphase 14C transport through the thick Yucca Flat alluvial basin was performed to estimate the magnitude of radionuclide attenuation occurring within the unsaturated zone. Parameterization of the 14C transport in the multiphase flow and transport simulator (FEHM) was verified with experimental data collected from a large unsaturated soil column experiment. The experimental data included 14C as a radio-labeled bicarbonate solution, SF6 gas, and lithium bromide solution breakthroughs. Two representative simulation cases with working points located at shallow and deep depths relative to the water table were created to investigate the impact of subsidence crater-enhanced recharge, crater-playa areal extent, gas-phase partitioning, solid-phase partitioning, and a reduced permeability/porosity compressed zone created during the explosion on 14C transport. The representative shallow test had a detonation point located 175 m below land surface, and the deep test had a working point 435 m below land surface in a 500 m deep unsaturated zone. Carbon-14 transport is influenced by gas-phase diffusion and sorption within the alluvium. Gas-phase diffusion is an attenuation mechanism that transports 14C gas as 14CO2 throughout the unsaturated zone and exposes it to a large amount of soil moisture, resulting in dilute concentrations. The simulations indicated that the majority of the 14C inventory remains in the unsaturated zone over a 1,000-year time period after detonation because gas-phase diffusion moves the bulk of the 14C away from the higher recharge occurring in crater playas. Retardation also plays a role in slowing advective aqueous phase transport to the water

  1. Occurrence of synthetic musk fragrances in effluent and non-effluent impacted environments.

    PubMed

    Chase, Darcy A; Karnjanapiboonwong, Adcharee; Fang, Yu; Cobb, George P; Morse, Audra N; Anderson, Todd A

    2012-02-01

    Synthetic musk fragrances (SMFs) are considered micropollutants and can be found in various environmental matrices near wastewater discharge areas. These emerging contaminants are often detected in wastewater at low concentrations; they are continuously present and constitute a constant exposure source. Objectives of this study were to investigate the environmental fate, transport, and transformation of SMFs. Occurrence of six polycyclic musk compounds (galaxolide, tonalide, celestolide, phantolide, traseolide, cashmeran) and two nitro musk compounds (musk xylene and musk ketone) was monitored in wastewater, various surface waters and their sediments, as well as groundwater, soil cores, and plants from a treated wastewater land application site. Specifically, samples were collected quarterly from (1) a wastewater treatment plant to determine initial concentrations in wastewater effluent, (2) a storage reservoir at a land application site to determine possible photolysis before land application, (3) soil cores to determine the amount of sorption after land application and groundwater recharge to assess lack thereof, (4) a lake system and its sediment to assess degradation, and (5) non-effluent impacted local playa lakes and sediments to assess potential sources of these compounds. All samples were analyzed using gas chromatography coupled with mass spectrometry (GC-MS). Data indicated that occurrence of SMFs in effluent-impacted environments was detectable at ng/L and ng/g concentrations, which decreased during transport throughout wastewater treatment and land application. However, unexpected concentrations, ng/L and ng/g, were also detected in playa lakes not receiving treated effluent. Additionally, soil cores from land application sites had ng/g concentrations, and SMFs were detected in plant samples at trace levels. Galaxolide and tonalide were consistently found in all environments. Information on occurrence is critical to assessing exposure to these potential

  2. Persistent leatherback turtle migrations present opportunities for conservation.

    PubMed

    Shillinger, George L; Palacios, Daniel M; Bailey, Helen; Bograd, Steven J; Swithenbank, Alan M; Gaspar, Philippe; Wallace, Bryan P; Spotila, James R; Paladino, Frank V; Piedra, Rotney; Eckert, Scott A; Block, Barbara A

    2008-07-15

    Effective transboundary conservation of highly migratory marine animals requires international management cooperation as well as clear scientific information about habitat use by these species. Populations of leatherback turtles (Dermochelys coriacea) in the eastern Pacific have declined by >90% during the past two decades, primarily due to unsustainable egg harvest and fisheries bycatch mortality. While research and conservation efforts on nesting beaches are ongoing, relatively little is known about this population of leatherbacks' oceanic habitat use and migration pathways. We present the largest multi-year (2004-2005, 2005-2006, and 2007) satellite tracking dataset (12,095 cumulative satellite tracking days) collected for leatherback turtles. Forty-six females were electronically tagged during three field seasons at Playa Grande, Costa Rica, the largest extant nesting colony in the eastern Pacific. After completing nesting, the turtles headed southward, traversing the dynamic equatorial currents with rapid, directed movements. In contrast to the highly varied dispersal patterns seen in many other sea turtle populations, leatherbacks from Playa Grande traveled within a persistent migration corridor from Costa Rica, past the equator, and into the South Pacific Gyre, a vast, low-energy, low-productivity region. We describe the predictable effects of ocean currents on a leatherback migration corridor and characterize long-distance movements by the turtles in the eastern South Pacific. These data from high seas habitats will also elucidate potential areas for mitigating fisheries bycatch interactions. These findings directly inform existing multinational conservation frameworks and provide immediate regions in the migration corridor where conservation can be implemented. We identify high seas locations for focusing future conservation efforts within the leatherback dispersal zone in the South Pacific Gyre. PMID:18630987

  3. Alluvial fan facies in Death Valley: Contrasts with fluvial gravels and implications for the interpretation of ancient fan'' gravels

    SciTech Connect

    Middleton, G.V. . Dept. of Geology)

    1993-03-01

    Sedimentary environments in Death Valley belong to three major groups: fans, washes, and playas. Fans in Death Valley include both diamicts and bedded gravels. Seven facies may be recognized. The diamicts include: (1) matrix-rich, coarse wackestones; (2) thin, matrix-rich, fine wackestones, that may show grading; (3) matrix-poor, coarse packstones, transitional to wackestones. The bedded facies include: (4) weakly bedded, poorly sorted packstones or grainstones, that show patchy imbrication, and cut-and-fill structures; (5) packed, imbricated cobble lenses, generally interbedded in facies 4; (6) distinctly bedded gravels, that are better bedded, finer and better sorted, and show better imbrication than facies 4, but still do not show clear separation of sand and gravel beds; (7) backfill cross-bedded gravels. Sand beds are not seen in fan deposits. Sand is present in eolian deposits of the playa, as plane-laminated, back-eddy deposits in Death Valley Wash, and as laminated or rippled sand in the Amargosa River, which drains into the south end of Death Valley. The most remarkable features of the fan and wash deposits are the very weak segregation of sand and gravel, and the absence of any lower flow-regime structures produced by ripples or dunes. During floods, the slope of fan and wash surfaces is steep enough to produce upper regime flows. Most fans in Death Valley itself are not strongly dominated by debris flow deposits (diamicts). Within a fan, facies vary little from proximal to distal regions, but may differ strongly from facies seen in adjacent fans.

  4. Groundwater flow near the Shoal Site, Sand Springs Range, Nevada: Impact of density-driven flow

    SciTech Connect

    Chapman, J.; Mihevc, T.; McKay, A.

    1994-09-01

    The nature of flow from a highland recharge area in a mountain range in north-central Nevada to discharge areas on either side of the range is evaluated to refine a conceptual model of contaminant transport from an underground nuclear test conducted beneath the range. The test, known as the Shoal event, was conducted in 1963 in granitic rocks of the Sand Springs Range. Sparse hydraulic head measurements from the early 1960s suggest flow from the shot location to the east to Fairview Valley, while hydrochemistry supports flow to salt pans in Fourmile Flat to the west. Chemical and isotopic data collected from water samples and during well-logging arc best explained by a reflux brine system on the west side of the Sand Springs Range, rather than a typical local flow system where all flow occurs from recharge areas in the highlands to a central discharge area in a playa. Instead, dense saline water from the playa is apparently being driven toward the range by density contrasts. The data collected between the range and Fourmile Flat suggest the groundwater is a mixture of younger, fresher recharge water with older brine. Chemical contrasts between groundwater in the east and west valleys reflect the absence of re-flux water in Fairview Valley because the regional discharge area is distant and thus there is no accumulation of salts. The refluxing hydraulic system probably developed after the end of the last pluvial period and differences between the location of the groundwater divide based on hydraulic and chemical indicators could reflect movement of the divide as the groundwater system adjusts to the new reflux condition.

  5. Rocky 7 prototype Mars rover field geology experiments 1. Lavic Lake and sunshine volcanic field, California

    USGS Publications Warehouse

    Arvidson, R. E.; Acton, C.; Blaney, D.; Bowman, J.; Kim, S.; Klingelhofer, G.; Marshall, J.; Niebur, C.; Plescia, J.; Saunders, R.S.; Ulmer, C.T.

    1998-01-01

    Experiments with the Rocky 7 rover were performed in the Mojave Desert to better understand how to conduct rover-based, long-distance (kilometers) geological traverses on Mars. The rover was equipped with stereo imaging systems for remote sensing science and hazard avoidance and 57Fe Mo??ssbauer and nuclear magnetic resonance spectrometers for in situ determination of mineralogy of unprepared rock and soil surfaces. Laboratory data were also obtained using the spectrometers and an X ray diffraction (XRD)/XRF instrument for unprepared samples collected from the rover sites. Simulated orbital and descent image data assembled for the test sites were found to be critical for assessing the geologic setting, formulating hypotheses to be tested with rover observations, planning traverses, locating the rover, and providing a regional context for interpretation of rover-based observations. Analyses of remote sensing and in situ observations acquired by the rover confirmed inferences made from orbital and simulated descent images that the Sunshine Volcanic Field is composed of basalt flows. Rover data confirmed the idea that Lavic Lake is a recharge playa and that an alluvial fan composed of sediments with felsic compositions has prograded onto the playa. Rover-based discoveries include the inference that the basalt flows are mantled with aeolian sediment and covered with a dense pavement of varnished basalt cobbles. Results demonstrate that the combination of rover remote sensing and in situ analytical observations will significantly increase our understanding of Mars and provide key connecting links between orbital and descent data and analyses of returned samples. Copyright 1998 by the American Geophysical Union.

  6. Persistent Leatherback Turtle Migrations Present Opportunities for Conservation

    PubMed Central

    Shillinger, George L; Palacios, Daniel M; Bailey, Helen; Bograd, Steven J; Swithenbank, Alan M; Gaspar, Philippe; Wallace, Bryan P; Spotila, James R; Paladino, Frank V; Piedra, Rotney; Eckert, Scott A; Block, Barbara A

    2008-01-01

    Effective transboundary conservation of highly migratory marine animals requires international management cooperation as well as clear scientific information about habitat use by these species. Populations of leatherback turtles (Dermochelys coriacea) in the eastern Pacific have declined by >90% during the past two decades, primarily due to unsustainable egg harvest and fisheries bycatch mortality. While research and conservation efforts on nesting beaches are ongoing, relatively little is known about this population of leatherbacks' oceanic habitat use and migration pathways. We present the largest multi-year (2004–2005, 2005–2006, and 2007) satellite tracking dataset (12,095 cumulative satellite tracking days) collected for leatherback turtles. Forty-six females were electronically tagged during three field seasons at Playa Grande, Costa Rica, the largest extant nesting colony in the eastern Pacific. After completing nesting, the turtles headed southward, traversing the dynamic equatorial currents with rapid, directed movements. In contrast to the highly varied dispersal patterns seen in many other sea turtle populations, leatherbacks from Playa Grande traveled within a persistent migration corridor from Costa Rica, past the equator, and into the South Pacific Gyre, a vast, low-energy, low-productivity region. We describe the predictable effects of ocean currents on a leatherback migration corridor and characterize long-distance movements by the turtles in the eastern South Pacific. These data from high seas habitats will also elucidate potential areas for mitigating fisheries bycatch interactions. These findings directly inform existing multinational conservation frameworks and provide immediate regions in the migration corridor where conservation can be implemented. We identify high seas locations for focusing future conservation efforts within the leatherback dispersal zone in the South Pacific Gyre. PMID:18630987

  7. Ancient sedimentary structures in the <3.7 Ga Gillespie Lake Member, Mars, that resemble macroscopic morphology, spatial associations, and temporal succession in terrestrial microbialites.

    PubMed

    Noffke, Nora

    2015-02-01

    Sandstone beds of the <3.7 Ga Gillespie Lake Member on Mars have been interpreted as evidence of an ancient playa lake environment. On Earth, such environments have been sites of colonization by microbial mats from the early Archean to the present time. Terrestrial microbial mats in playa lake environments form microbialites known as microbially induced sedimentary structures (MISS). On Mars, three lithofacies of the Gillespie Lake Member sandstone display centimeter- to meter-scale structures similar in macroscopic morphology to terrestrial MISS that include "erosional remnants and pockets," "mat chips," "roll-ups," "desiccation cracks," and "gas domes." The microbially induced sedimentary-like structures identified in Curiosity rover mission images do not have a random distribution. Rather, they were found to be arranged in spatial associations and temporal successions that indicate they changed over time. On Earth, if such MISS occurred with this type of spatial association and temporal succession, they would be interpreted as having recorded the growth of a microbially dominated ecosystem that thrived in pools that later dried completely: erosional pockets, mat chips, and roll-ups resulted from water eroding an ancient microbial mat-covered sedimentary surface; during the course of subsequent water recess, channels would have cut deep into the microbial mats, leaving erosional remnants behind; desiccation cracks and gas domes would have occurred during a final period of subaerial exposure of the microbial mats. In this paper, the similarities of the macroscopic morphologies, spatial associations, and temporal succession of sedimentary structures on Mars to MISS preserved on Earth has led to the following hypothesis: The sedimentary structures in the <3.7 Ga Gillespie Lake Member on Mars are ancient MISS produced by interactions between microbial mats and their environment. Proposed here is a strategy for detecting, identifying, confirming, and differentiating

  8. Using remote sensing and GIS techniques to estimate discharge and recharge fluxes for the Death Valley regional groundwater flow system, USA

    USGS Publications Warehouse

    D'Agnese, F. A.; Faunt, C.C.; Turner, A.K.; ,

    1996-01-01

    The recharge and discharge components of the Death Valley regional groundwater flow system were defined by techniques that integrated disparate data types to develop a spatially complex representation of near-surface hydrological processes. Image classification methods were applied to multispectral satellite data to produce a vegetation map. The vegetation map was combined with ancillary data in a GIS to delineate different types of wetlands, phreatophytes and wet playa areas. Existing evapotranspiration-rate estimates were used to calculate discharge volumes for these area. An empirical method of groundwater recharge estimation was modified to incorporate data describing soil-moisture conditions, and a recharge potential map was produced. These discharge and recharge maps were readily converted to data arrays for numerical modelling codes. Inverse parameter estimation techniques also used these data to evaluate the reliability and sensitivity of estimated values.The recharge and discharge components of the Death Valley regional groundwater flow system were defined by remote sensing and GIS techniques that integrated disparate data types to develop a spatially complex representation of near-surface hydrological processes. Image classification methods were applied to multispectral satellite data to produce a vegetation map. This map provided a basis for subsequent evapotranspiration and infiltration estimations. The vegetation map was combined with ancillary data in a GIS to delineate different types of wetlands, phreatophytes and wet playa areas. Existing evapotranspiration-rate estimates were then used to calculate discharge volumes for these areas. A previously used empirical method of groundwater recharge estimation was modified by GIS methods to incorporate data describing soil-moisture conditions, and a recharge potential map was produced. These discharge and recharge maps were readily converted to data arrays for numerical modelling codes. Inverse parameter

  9. Near-wall vorticity measurements at the SLTST site

    NASA Astrophysics Data System (ADS)

    Foss, John; Treat, Scott; Neal, Douglas

    2003-11-01

    Two, four-sensor, vorticity probes were positioned at 15cm above the playa (desert floor) at the STLTEST [1] site (13 June 2003). Portions of the 3-hour record exhibit neutral stability conditions. The recently developed (Hicks, et al. [2]) 100kHz Pulse Width Modulated-Constant Temperature Anemometer was sampled at 50kHz to ensure the complete resolution of the smallest scales of motion. ω _z(t) and ω _y(t) data, derived using the processing algorithms described in Foss and Hicks [3], will be interrogated for insight into the balance: partial u'v'/partial y = v'ω z w'ω _y+ as well as various turbulence properties. ONR support (N00014-00-1-0753), R. Joslin, Program Director, through a subcontract from the Univ. of Utah, is gratefully acknowledged for these experiments. [1] J.C. Klewicki and M.M. Metzger, "Studies of high Reynolds number turbulence in the atmospheric surface layer over the salt playa of western Utah," in A.J. Smits, ed. IUTAM Symposium on Reynolds Number Scaling in Turbulent Flow, Kluwer, Princeton, NJ, 2002. [2] J.F. Foss and Hicks, T.J., "Processing Time Series Data (Velocity, Shear Stress) from the Pulse Width Modulated-Constant Temperature Anemometer (PWM-CTA)", 19th International Congress on Instrumentation in Aerospace Simulations Facilities, IEEE, pp. 448-453 (2001). [3] Hicks, T.J., J.K. Schwannecke, M.J. Norconk, A.M. Hellum and J.F. Foss, "The Evolved 100kHz PWM-CTA", ICIASF'03, Göttengen, Germany, 2003.

  10. Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers

    PubMed Central

    2010-01-01

    Background Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers Dry Lakes. We surveyed branchiopods during the wet season to estimate abundances and then conducted a laboratory microcosm experiment, in which dried sediment containing cysts and the overlying algal crust were inundated and cultured. Microcosm trials were run with and without shrimps; each type of trial was run for two lengths of time: 30 and 60 days. We estimated the effect of shrimps on algae by measuring chlorophyll content and the relative abundance of algal species. Results We found two species of fairy shrimps (Branchinecta mackini and B. gigas), one tadpole shrimp (Lepidurus lemmoni), and a clam shrimp (Cyzicus setosa) in our wet-season field survey. We collected Branchinecta lindahli in a pilot study, but not subsequently. The dominant taxa were C. setosa and B. mackini, but abundances and species composition varied greatly among playas. The same species found in field surveys also occurred in the microcosm experiment. There were no significant differences as a function of experimental treatments for either chlorophyll content or algal species composition (Microcoleus vaginatus dominated all treatments). Conclusions The results suggest that there was no direct effect of shrimps on algae. Although the pans harbored an apparently high abundance of branchiopods, these animals had little role in regulating primary producers in this environment. PMID:21143855

  11. Precipitation Based Malaria Patterns in the Amazon -- Will Deforestation Alter Risk?

    NASA Astrophysics Data System (ADS)

    Olson, S. H.; Durieux, L.; Elguero, E.; Foley, J.; Gagnon, R.; Guegan, J.; Patz, J.

    2007-12-01

    The World Health Organization, estimates that forty-two percent of malaria cases are "associated with policies and practices regarding land use, deforestation, water resource management, settlement siting and modified house design". This estimate was drawn from expert opinion and studies performed at local scales, but little research has investigated the cumulative impacts of land use and land cover changes occurring in the Amazon Basin on malaria. Much less is understood about the impact of changing land use and subsequent precipitation regimes on malaria risk. To understand how land use practices may alter malaria patterns in the Basin we present an analysis of municipio (n=755) malaria case data and monthly precipitation patterns between 1996 and 1999. Climate data originated from the CRU TS 2.1 half-degree grid resolution climate data set. We present a hierarchical (random coefficients) log-linear Poisson model relating malaria incidence to precipitation for both municipos and states. At the Basin scale precipitation and cases show strong relationships. Precipitation and cases are asynchronous across the period of observation, but detailed inspection of states and individual municipios reveal geographic dependencies of precipitation and malaria incidence. Future research will link the patterns of precipitation and malaria to anticipated changes in climate from deforestation in the Basin.

  12. Participatory Risk Mapping of Malaria Vector Exposure in Northern South America using Environmental and Population Data

    PubMed Central

    Fuller, D.O.; Troyo, A.; Alimi, T.O.; Beier, J.C.

    2014-01-01

    Malaria elimination remains a major public health challenge in many tropical regions, including large areas of northern South America. In this study, we present a new high spatial resolution (90 × 90 m) risk map for Colombia and surrounding areas based on environmental and human population data. The map was created through a participatory multi-criteria decision analysis in which expert opinion was solicited to determine key environmental and population risk factors, different fuzzy functions to standardize risk factor inputs, and variable factor weights to combine risk factors in a geographic information system. The new risk map was compared to a map of malaria cases in which cases were aggregated to the municipio (municipality) level. The relationship between mean municipio risk scores and total cases by muncípio showed a weak correlation. However, the relationship between pixel-level risk scores and vector occurrence points for two dominant vector species, Anopheles albimanus and An. darlingi, was significantly different (p < 0.05) from a random point distribution, as was a pooled point distribution for these two vector species and An. nuneztovari. Thus, we conclude that the new risk map derived based on expert opinion provides an accurate spatial representation of risk of potential vector exposure rather than malaria transmission as shown by the pattern of malaria cases, and therefore it may be used to inform public health authorities as to where vector control measures should be prioritized to limit human-vector contact in future malaria outbreaks. PMID:24976656

  13. THAO-CHILD HEALTH PROGRAMME: COMMUNITY BASED INTERVENTION FOR HEALTHY LIFESTYLES PROMOTION TO CHILDREN AND FAMILIES: RESULTS OF A COHORT STUDY.

    PubMed

    Gómez Santos, Santiago Felipe; Estévez Santiago, Rocío; Palacios Gil-Antuñano, Nieves; Leis Trabazo, Maria Rosaura; Tojo Sierra, Rafael; Cuadrado Vives, Carmen; Beltrán de Miguel, Beatriz; Ávila Torres, José Manuel; Varela Moreiras, Gregorio; Casas Esteve, Rafael

    2015-12-01

    Introducción: la obesidad infantil es una de las principales preocupaciones de salud pública. La etiología multifactorial y multinivel requiere de intervenciones complejas como las intervenciones de base comunitaria (CBI). El Programa Thao-Salud Infantil es una CBI implementada en España desde 2007. Objetivo: mostrar la metodología Thao y los últimos resultados transversales y longitudinales. Métodos: estudio de cohortes longitudinal (4 años de seguimiento) y estudio transversal. Resultados: el estudio longitudinal encontró un incremento del 1% en la prevalencia de exceso de peso tras 4 años de implementación del Programa Thao en 10 municipios con 6.697 niños y niñas involucrados. El estudio transversal llevado a cabo con 20.636 niños y niñas de 22 municipios encontró una prevalencia de exceso de peso infantil del 26,6%. Discusión: actualmente un freno en el incremento de la prevalencia de exceso de peso infantil es considerado como un éxito debido a la alta prevalencia a nivel mundial. Son necesarios más estudios metodológicamente bien realizados para conocer la eficacia de las CBI en este campo.

  14. [Genetic isolates and inbreeding customs in three rural municipalities from Honduras].

    PubMed

    Herrera-Paz, Edwin Francisco

    2016-01-01

    Introducción: el método de isonimia ha sido utilizado ampliamente para la determinación de la estructura genética aproximada de las poblaciones humanas. El objetivo del estudio fue evaluar la magnitud del aislamiento genético y las costumbres endogámicas en 57 comunidades de tres municipios rurales de Honduras utilizando las técnicas de isonimia. Métodos: se utilizó el listado de 408 apellidos diferentes utilizados por 20 712 votantes registrados en el Tribunal Supremo Electoral, que residen en las 57 comunidades estudiadas. Para cada comunidad se calcularon los valores de la isonimia aleatoria (IR), no aleatoria (IN) y total (IT) con el fin de evaluar los coeficientes de consanguinidad FST, FIS y FIT. Resultados: se encontró alta consanguinidad debido a aislamiento y a costumbres endogámicas en muchas comunidades. En los tres municipios se observó desviación significativa del comportamiento exógamo típico de otras poblaciones de Honduras. Conclusiones: muchas de las comunidades estudiadas presentan una elevada consanguinidad debido al aislamiento, la segregación étnica y/o costumbres endogámicas.

  15. [Thoughts on the spatial distribution of population].

    PubMed

    Borisovna, L; Velez, F

    1991-12-01

    Preliminary results of Mexico's 1990 census indicate that during the past decade population distribution in Puebla followed the traditional Mexican pattern of concentration and dispersion. 10 of Puebla's 217 municipios had over 50,000 inhabitants and were home to 43.6% of the state's population on 8% of its territory. The municipios of the city of Puebla contained over 25% of the state population. 74 municipios had 10,000-40,000 inhabitants, or 42% of the population on 51% of the territory. The 133 municipios with populations under 10,000 contained 14% of the state population on 41% of its territory. The demographic growth of the state is clearly related to that of the capital. The city of Puebla absorbed 11% of the state population in 1940, 15% in 1960, and 26% in 1991. Its population of 1,054,921 in 1990 was much higher than that of the next largest city, Tehuacan, with 155,174. The Puebla metropolitan zone covers 1340 sq km and includes 16 municipios, 10 in the state of Puebla and 6 in Tlaxcala. 1980 statistics show that the metropolitan zone concentrated 37.5% of the state's industrial establishments, 50% of industrial capital investment, and 58% of industrial manpower, and generated 53% of crude industrial production. About 1/4 of immigrants to the state live in the city of Puebla. 65% of migrants are aged 15-49 years, vs. 49% of the native population. 44% of the native population but only 13% the immigrant population is aged under 15 years. 31% of migrants were aged 15-24 years when they moved to Puebla. A considerably higher proportion of migrants than natives to the city of Puebla are in consensual unions. Most migrant to Puebla come from nearby states: Veracruz, Tlaxcala, Oaxaca, and recently Mexico City. Slightly over 1/3 of nonnatives in the city of Puebla are from Puebla state. Inmigrants are evenly divided between those of rural and urban origin, but those of urban origin travelled farther to the city. Women predominated among rural migrants to the

  16. Geohydrology and water utilization in the Willcox Basin, Graham and Cochise Counties, Arizona

    USGS Publications Warehouse

    Brown, S.G.; Schumann, Herbert H.

    1969-01-01

    The Willcox basin is an area of interior drainage in the northern part of Sulphur Springs Valley, Cochise and Graham Counties, Ariz. The basin comprises about 1,500 square miles, of which the valley floor occupies about 950 square miles. The basin probably formed during middle and late Tertiary time, when the area was subjected to large-scale faulting accompanied by the uplift of the mountain ranges that presently border it. During and after faulting, large quantities of alluvium were deposited in the closed basin. The rocks in the basin are divided into two broad groups--the rocks of the mountain blocks, of Precambrian through Tertiary age, and the rocks of the basin, of Tertiary and Quaternary age. The mountain blocks consist of igneous, metamorphic, and sedimentary rocks; the water-bearing characteristics of these rocks depend primarily on their degree of weathering and fracturing. Even in areas where these rocks are fractured and jointed, only small amounts of water have been developed. The rocks of the basin consist of moderately consolidated alluvium, poorly consolidated alluvium, and unconsolidated alluvium. The water-bearing characteristics of the moderately and poorly consolidated alluvium are not well known. The unconsolidated alluvium underlies most of the valley floor and consists of two facies, stream deposits and lake beds associated with the old playa. The lenticular sand and gravel layers interbedded in silt- and clay-size material of the unconsolidated alluvium constitute the principal aquifer in the basin. The other aquifers, which yield less water, consist of beds of poorly to moderately consolidated sand- and gravel-size material; these beds occur in both the poorly consolidated and moderately consolidated alluvium. In the Stewart area the median specific capacity of wells per 100 feet of saturated unconsolidated alluvium was 20 gallons per minute, and in the Kansas Settlement area the specific capacity of wells penetrating the poorly and

  17. [Analysis of the definitive statistics of the 11th General Population and Housing Census].

    PubMed

    Aguayo Hernandez, J R

    1992-01-01

    The 11th General Census of Population and Housing conducted in March 1990 enumerated 2,204,054 inhabitants in Sinaloa, for a density of 37.9 per sq. km. Sinaloa's population thus increased sevenfold from 297,000 in 1900. The proportion of Sinalioans in Mexico's population increased from 2.2% in 1900 to 2.7% in 1990. 38.4% of the population was under age 14, 57.0% was 14064, and 4.6% as over 65. The greatest challenge for the year 2010 will be to meet the demand for educational facilities, employment, and services for the growing elderly population. Sinaloa's population grew at an annual rate of 1.1 between 1980-90. 17 of its 18 municipios showed slowing growth rates between 1980-90, with only Escuinapa increasing its rate. Sinaloa's growth rate of 1.8% is still relatively high, and the population in the year 2000 is projected at 2.6 million. Population distribution and migration present problems that should be more actively addressed. Urban-urban migration is increasing in importance. In 1990, Sinaloa had 5247 localities of which only 85 had more than 2500 inhabitants and 4717 had fewer than 500. Growth of midsize localities with 500-2499 inhabitants may constitute an alternative allowing the demographic deconcentration and decentralization that Sinaloa urgently requires. The lack of jobs, infrastructure, educational and health services, housing, and food in the dispersed 4717 communities with fewer than 500 inhabitants makes them sources of emigration. Sinaloa's population is concentrated along the coast and in the 3 valleys of the north and central regions, which contain 80.8% of the population. One-third of the population lives on 12.1% of the territory in 2 municipios, while 12 municipios covering 67% of the territory contain just 24% of the population. Sinaloa's growth rate has declined from 4.3% between 1960-70 to 3.7% from 1970-80 and 1.8% in 1980-90.

  18. Earthquake behavior along the Levant fault from paleoseismology (Invited)

    NASA Astrophysics Data System (ADS)

    Klinger, Y.; Le Beon, M.; Wechsler, N.; Rockwell, T. K.

    2013-12-01

    The Levant fault is a major continental structure 1200 km-long that bounds the Arabian plate to the west. The finite offset of this left-lateral strike-slip fault is estimated to be 105 km for the section located south of the restraining bend corresponding roughly to Lebanon. Along this southern section the slip-rate has been estimated over a large range of time scales, from few years to few hundreds thousands of years. Over these different time scales, studies agree for the slip-rate to be 5mm/yr × 2 mm/yr. The southern section of the Levant fault is particularly attractive to study earthquake behavior through time for several reasons: 1/ The fault geometry is simple and well constrained. 2/ The fault system is isolated and does not interact with obvious neighbor fault systems. 3/ The Middle-East, where the Levant fault is located, is the region in the world where one finds the longest and most complete historical record of past earthquakes. About 30 km north of the city of Aqaba, we opened a trench in the southern part of the Yotvata playa, along the Wadi Araba fault segment. The stratigraphy presents silty sand playa units alternating with coarser sand sediments from alluvial fans flowing westwards from the Jordan plateau. Two fault zones can be recognized in the trench and a minimum of 8 earthquakes can be identified, based on upward terminations of ground ruptures. Dense 14C dating through the entire exposure allows matching the 4 most recent events with historical events in AD1458, AD1212, AD1068 and AD748. Size of the ground rupture suggests a bi-modal distribution of earthquakes with earthquakes rupturing the entire Wadi Araba segment and earthquakes ending in the extensional jog forming the playa. Timing of earthquakes shows that no earthquakes occurred at this site since about 600 years, suggesting earthquake clustering along this section of the fault and potential for a large earthquake in the near future. 3D paleoseismological trenches at the Beteiha

  19. Mutiple Isotope Forensics on Nitrate in the Poisoning of Wild Horses in 2007.

    NASA Astrophysics Data System (ADS)

    Michalski, G.; Dahman, C.; Earman, S.; Hershey, R.

    2008-12-01

    Multiple isotopes ratios in nitrate can be used as powerful tracers of biogeochemical ýprocesses and used in natural forensics. In June of 2007, 71 wild horses were found dead ýnear the Main Lake depression in the Cactus Flat playa at the U.S. Air Force's Nevada ýTest and Training Range in southern Nevada. Toxicology reports showed that the horses ýdied from acute nitrate poisoning and subsequent testing of the Main Lake depression ýwater showed that it contained nitrate concentrations as high as 10 times the ýrecommended limits for livestock. Concerns among land managers and the community ýled to extensive news coverage of the event, which fueled speculation that the high levels ýof nitrate were caused by dumping of deicing urea onto the playa. We conducted a ýmultiple isotope forensics study on nitrate obtained from the water, sediment, and soils ýfrom surrounding stream inlets to the playa. This included δ 15N, δ ýý18O, and Δ 17O analysis. Our δ 18O values were ýenriched (relative to SMOW) ~ 15‰ to 31‰ suggesting atmospheric ýdeposition, known to accumulate in arid soils, may be important. However, Δ ýý17O values of ~2‰ discounted atmospheric deposition as a significant ýsource of nitrate; we estimate only 10 % of the total load. The ýnitrate δ 15N values were extremely positive, ranging from 38‰ to ýý7.5‰, effectively ruling out the oxidation of urea (δ 15N -ýý1.0‰). The most probable scenario that would explain the high δ ýý15N and δ 18O low Δ 17O, and high [NO3-] is ýnitrogen in manure/urine with enriched δ 15N was deposited around the rim ýof the Main Lake depression during the dry summer and then partially volatilized, further ýenriching the δ 15N. During the winter, this N was dissolved by ýprecipitation and mixed with atmospheric nitrate. As the water in the Main Lake ýdepression evaporated over the next spring and summer, this N mixture slowly ýconcentrated. At some point, nitrification of NH4

  20. Stereo Pair: Patagonia, Argentina

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This view of northern Patagonia, near El Cain, Argentina shows complexly eroded volcanic terrain, with basalt mesas, sinkholes, landslide debris, playas, and relatively few integrated drainage channels. Surrounding this site (but also extending far to the east) is a broad plateau capped by basalt, the Meseta de Somuncura. Here, near the western edge of the plateau, erosion has broken through the basalt cap in a variety of ways. On the mesas, water-filled sinkholes (lower left) are most likely the result of the collapse of old lava tubes. Along the edges of the mesas (several locations) the basalt seems to be sliding away from the plateau in a series of slices. Water erosion by overland flow is also evident, particularly in canyons where vegetation blankets the drainage channels (green patterns, bottom of image). However, overland water flow does not extend very far at any location. This entire site drains to local playas, some of which are seen here (blue). While the water can reach the playas and then evaporate, what becomes of the eroded rock debris? Wind might excavate some of the finer eroded debris, but the fate of much of the missing bedrock remains mysterious.

    This cross-eyed stereoscopic image pair was generated using topographic data from the Shuttle Radar Topography Mission, combined with an enhanced Landsat 7 satellite color image. The topography data are used to create two differing perspectives of a single image, one perspective for each eye. In doing so, each point in the image is shifted slightly, depending on its elevation. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions.

    Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The

  1. Anaglyph: Patagonia, Argentina

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This view of northern Patagonia, near El Cain, Argentina shows complexly eroded volcanic terrain, with basalt mesas, sinkholes, landslide debris, playas, and relatively few integrated drainage channels. Surrounding this site (but also extending far to the east) is a broad plateau capped by basalt, the Meseta de Somuncura. Here, near the western edge of the plateau, erosion has broken through the basalt cap in a variety of ways. On the mesas, water-filled sinkholes (lower left) are most likely the result of the collapse of old lava tubes. Along the edges of the mesas (several locations) the basalt seems to be sliding away from the plateau in a series of slices. Water erosion by overland flow is also evident, particularly in canyons where vegetation blankets the drainage channels (bright patterns, bottom of image). However, overland water flow does not extend very far at any location. This entire site drains to local playas, some of which are seen here (dark lakes with bright shores). While the water can reach the playas and then evaporate, what becomes of the eroded rock debris? Wind might excavate some of the finer eroded debris, but the fate of much of the missing bedrock remains mysterious.

    This anaglyph was generated by first draping a Landsat Thematic Mapper image over a topographic map from the Shuttle Radar Topography Mission, then producing the two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and the right eye with a blue filter.

    Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7 Thematic Mapper image used here was

  2. Stratigraphy and sedimentology of a dry to wet eolian depositional system, Burns formation, Meridiani Planum, Mars

    NASA Astrophysics Data System (ADS)

    Grotzinger, J. P.; Arvidson, R. E.; Bell, J. F.; Calvin, W.; Clark, B. C.; Fike, D. A.; Golombek, M.; Greeley, R.; Haldemann, A.; Herkenhoff, K. E.; Jolliff, B. L.; Knoll, A. H.; Malin, M.; McLennan, S. M.; Parker, T.; Soderblom, L.; Sohl-Dickstein, J. N.; Squyres, S. W.; Tosca, N. J.; Watters, W. A.

    2005-11-01

    Outcrop exposures of sedimentary rocks at the Opportunity landing site (Meridiani Planum) form a set of genetically related strata defined here informally as the Burns formation. This formation can be subdivided into lower, middle, and upper units which, respectively, represent eolian dune, eolian sand sheet, and mixed eolian sand sheet and interdune facies associations. Collectively, these three units are at least 7 m thick and define a "wetting-upward" succession which records a progressive increase in the influence of groundwater and, ultimately, surface water in controlling primary depositional processes. The Burns lower unit is interpreted as a dry dune field (though grain composition indicates an evaporitic source), whose preserved record of large-scale cross-bedded sandstones indicates either superimposed bedforms of variable size or reactivation of lee-side slip faces by episodic (possibly seasonal) changes in wind direction. The boundary between the lower and middle units is a significant eolian deflation surface. This surface is interpreted to record eolian erosion down to the capillary fringe of the water table, where increased resistance to wind-induced erosion was promoted by increased sediment cohesiveness in the capillary fringe. The overlying Burns middle unit is characterized by fine-scale planar-laminated to low-angle-stratified sandstones. These sandstones accumulated during lateral migration of eolian impact ripples over the flat to gently undulating sand sheet surface. In terrestrial settings, sand sheets may form an intermediate environment between dune fields and interdune or playa surfaces. The contact between the middle and upper units of the Burns formation is interpreted as a diagenetic front, where recrystallization in the phreatic or capillary zones may have occurred. The upper unit of the Burns formation contains a mixture of sand sheet facies and interdune facies. Interdune facies include wavy bedding, irregular lamination with

  3. Equatorial Layered Deposits in Arabia Terra, Mars: Facies and Process Variability

    NASA Astrophysics Data System (ADS)

    Pondrelli, M.; Rossi, A.; van Gasselt, S.; Le Deit, L.; Glamoclija, M.; Cavalazzi, B.; Franchi, F.; Fueten, F.; Hauber, E.; Zegers, T.

    2012-12-01

    Genetic mechanisms proposed to explain Equatorial Layered Deposits (ELDs) formation include subglacial volcanism, aeolian/airfall, lacustrine, lacustrine/volcanic and spring-fed deposition. ELDs have been frequently shown to consist of sulfates (e.g. Gendrin et al., 2005) that might form as a response to evaporation in a playa environment (Hoefen et al., 2003) or during spring precipitation (e.g. Allen and Oehler, 2008; Rossi et al., 2008). The importance of groundwater-dominated hydrological systems was proposed to explain the formation of light-toned deposits in Meridiani Planum and Arabia Terra (e.g. Andrews-Hanna et al. 2007). Additionally, fluid expulsion processes have been invoked to explain the formation of mounds within the light-toned deposits in Arabia Terra (Allen and Oehler, 2008; Rossi et al., 2008; Pondrelli et al., 2011). Potential for habitable conditions of both playa and spring-related settings (Cavalazzi et al., 2007; Glamoclija et al., 2011) coupled with the high preservation potential within sulfates (Panieri et al., 2010), make these deposits a good candidate to understand the potential past habitability of the planet. In order to investigate ELDs genesis, an area in the vicinity of Firsoff crater, where ELDs are present within and outside the craters, was selected for geological mapping and analysis of the landforms and their association using the available dataset, including CRISM in order to infer ELDs composition. Within Firsoff crater, ELDs form a bulge that can be estimated to be at least a few hundred meters thick, while, outside the craters, ELDs form flat-lying deposits. Although heavily eroded by wind and carved by yardangs, several morphologies within the ELDs in the craters seem to be depositional, which would exclude that the entire Firsoff basin had been originally filled by ELDs. Within craters, ELDs consist of roughly meter thick layers draping and onlapping the substratum. They appear affected by polygonal patterns with no

  4. An AEM-TEM study of weathering and diagenesis, Abert Lake, Oregon: II. Diagenetic modification of the sedimentary assemblage

    USGS Publications Warehouse

    Banfield, J.F.; Jones, B.F.; Veblen, D.R.

    1991-01-01

    This paper compares the mineralogy and chemistry of clay minerals in sediments from various depths and positions in Abert Lake and surrounding playa with those of the weathered materials entering the lake in order to reveal the nature and extent of post-depositional mineralogical modification. Analytical electron microscope (AEM) data from individual clay particles reveal that each sample is comprised of a highly inhomogeneous smectite assemblage. The thin clay flakes (commonly less than 10 nm wide) display a complete range in octahedral sheet compositions from nearly dioctahedral to nearly trioctahedral. The very abundant Mg-rich lake smectites with an estimated composition K0.29(Al0.23-Mg2.16Fe0.30)Si3.80Al0.20O10(OH)2 are not formed by weathering. This confirms the importance of diagenetic Mg uptake. Lattice-fringe imaging failed to reveal distinct brucite-like or vermiculite-like layers, suggesting that interstratifications of this type are rare or absent. Siliceous coatings on clay particles (identified by silica excess in smectite analyses) seem to favor topotactic overgrowth of stevensite rather than addition of brucite-like layers to the dioctahedral nuclei. The growth of K-stevensite dilutes the Al content of the crystal, and thus the increasing diagenetic modification reduces rather than supplements its illite component. Smectite compositions within individual samples were highly variable, yet source-related characteristics such as the abundance of Fe-rich smectite were apparent. Little evidence for systematic K or Mg enrichment with depth was identified in samples from depths of down to 16 feet below the sediment-water interface. The most magnesian assemblages are associated both with weathering sources of Mg-rich smectite and playa environments subjected to repeated wetting and drying cycles. Thus, the observations suggest that clay compositions primarily reflect changes in lake levels, brine composition, and source characteristics, rather than time and

  5. Mulitple Origins of Sand Dune-Topography Interactions on Titan

    NASA Astrophysics Data System (ADS)

    Goggin, H.; Ewing, R. C.; Hayes, A.; Cisneros, J.; Epps, J. C.

    2015-12-01

    The interaction between sand dune patterns and topographic obstacles is a primary signal of sand transport direction in the equatorial region of Saturn's moon, Titan. The streamlined, tear drop appearance of the sand-dune patterns as they wrap around obstacles and a dune-free zone on the east side of many obstacles gives the impression that sand transport is from the west to east at equatorial latitudes. However, the physical mechanism behind the dune-obstacle interaction is not well explained, leaving a gap in our understanding of the equatorial sand transport and implied wind directions and magnitudes on Titan. In order to better understand this interaction and evaluate wind and sand transport direction, we use morphometric analysis of optical images on Earth and Cassini SAR images on Titan combined with analog wind tunnel experiments to study dune-topography interactions. Image analysis is performed in a GIS environment to map spatial variations in dune crestline orientations proximal to obstacles. We also use digital elevation models to and analyze the three-dimensional geometry - height, length, width and slope of the dune-topography relationships on Earth. Preliminary results show that dune patterns are deflected similarly around positive, neutral, or negative topography, where positive topography is greater than the surrounding dune height, neutral topography is at dune height and negative topography is lower than dune heights. In the latter case these are typically intra-dune field playas. The obstacle height, width, slope and wind variability appear to play a primary role in determining if a lee-dune, rather than a dune-free lee-zone, develops. In many cases a dune-free playa with evaporite and mud desiccation polygons forms lee-ward of the obstacle. To support and elaborate on the mapping and spatial characterization of dune-topography interactions, a series of experiments using a wind tunnel were conducted. Wind tunnel experiments examine the formation

  6. Large landslides, composed of megabreccia, interbedded in Miocene basin deposits, southeastern Arizona

    USGS Publications Warehouse

    Krieger, Medora Louise Hooper

    1977-01-01

    The landslides in the Kearny and El Capitan Mountain quadrangles, Pinal and Gila Counties, Ariz., are tabular or lens like masses of megabreccia enclosed in Miocene basin deposits. The megabreccias within individual slide blocks are composed of pervasively brecciated Precambrian and younger formations that remain in normal stratigraphic sequence, indicating that each landslide moved as a fairly coherent mass. The megabreccias consist of fresh, mostly angular rock fragments in a comminuted matrix of the same composition as the fragments. The matrix ranges in amount from sparse to abundant. Where the matrix is sparse, the fragments fit tightly with little or no rotation. Locally fragments are rotated but not moved far; most units within a slide block are lithologically homogeneous. The Kearny landslides are conformably interbedded in steeply east-dipping playa and alluvial deposits. They form map units from a few tens of meters to nearly 4 km long and from less than 1 to 270 m wide. Narrow ridges expose sections through the landslides at about right angles to the direction of movement. The upper (proximal) ends have been eroded; the lower (distal) ends are buried. The El Capitan landslide dips very gently southward. Although partly dissected during erosion of the enclosing alluvial and lakebed deposits, its approximate original outline is still preserved. It forms a thin sheet, 5-15 m thick and at least 3.8 km long; the maximum outcrop width, near its distal end, is about 1.5 km. The Kearny landslides show little evidence of having exerted differential pressure on the underlying soft playa and alluvial deposits, and the contacts with the underlying sediments have little relief. The distal end of the El Capitan landslide, on the other hand, has considerable relief. As the landslide came to an abrupt stop, the end plowed into the underlying sediments, compressing them into fol9.s and forming sandstone dikes. The source of the El Capitan landslide is a well

  7. Microbially mediated mineral carbonation

    NASA Astrophysics Data System (ADS)

    Power, I. M.; Wilson, S. A.; Dipple, G. M.; Southam, G.

    2010-12-01

    Mineral carbonation involves silicate dissolution and carbonate precipitation, which are both natural processes that microorganisms are able to mediate in near surface environments (Ferris et al., 1994; Eq. 1). (Ca,Mg)SiO3 + 2H2CO3 + H2O → (Ca,Mg)CO3 + H2O + H4SiO4 + O2 (1) Cyanobacteria are photoautotrophs with cell surface characteristics and metabolic processes involving inorganic carbon that can induce carbonate precipitation. This occurs partly by concentrating cations within their net-negative cell envelope and through the alkalinization of their microenvironment (Thompson & Ferris, 1990). Regions with mafic and ultramafic bedrock, such as near Atlin, British Columbia, Canada, represent the best potential sources of feedstocks for mineral carbonation. The hydromagnesite playas near Atlin are a natural biogeochemical model for the carbonation of magnesium silicate minerals (Power et al., 2009). Field-based studies at Atlin and corroborating laboratory experiments demonstrate the ability of a microbial consortium dominated by filamentous cyanobacteria to induce the precipitation of carbonate minerals. Phototrophic microbes, such as cyanobacteria, have been proposed as a means for producing biodiesel and other value added products because of their efficiency as solar collectors and low requirement for valuable, cultivable land in comparison to crops (Dismukes et al., 2008). Carbonate precipitation and biomass production could be facilitated using specifically designed ponds to collect waters rich in dissolved cations (e.g., Mg2+ and Ca2+), which would allow for evapoconcentration and provide an appropriate environment for growth of cyanobacteria. Microbially mediated carbonate precipitation does not require large quantities of energy or chemicals needed for industrial systems that have been proposed for rapid carbon capture and storage via mineral carbonation (e.g., Lackner et al., 1995). Therefore, this biogeochemical approach may represent a readily

  8. Biologically induced mineralization of dypingite by cyanobacteria from an alkaline wetland near Atlin, British Columbia, Canada

    PubMed Central

    Power, Ian M; Wilson, Siobhan A; Thom, James M; Dipple, Gregory M; Southam, Gordon

    2007-01-01

    Background This study provides experimental evidence for biologically induced precipitation of magnesium carbonates, specifically dypingite (Mg5(CO3)4(OH)2·5H2O), by cyanobacteria from an alkaline wetland near Atlin, British Columbia. This wetland is part of a larger hydromagnesite (Mg5(CO3)4(OH)2·4H2O) playa. Abiotic and biotic processes for magnesium carbonate precipitation in this environment are compared. Results Field observations show that evaporation of wetland water produces carbonate films of nesquehonite (MgCO3·3H2O) on the water surface and crusts on exposed surfaces. In contrast, benthic microbial mats possessing filamentous cyanobacteria (Lyngbya sp.) contain platy dypingite (Mg5(CO3)4(OH)2·5H2O) and aragonite. Bulk carbonates in the benthic mats (δ13C avg. = 6.7‰, δ18O avg. = 17.2‰) were isotopically distinguishable from abiotically formed nesquehonite (δ13C avg. = 9.3‰, δ18O avg. = 24.9‰). Field and laboratory experiments, which emulated natural conditions, were conducted to provide insight into the processes for magnesium carbonate precipitation in this environment. Field microcosm experiments included an abiotic control and two microbial systems, one containing ambient wetland water and one amended with nutrients to simulate eutrophic conditions. The abiotic control developed an extensive crust of nesquehonite on its bottom surface during which [Mg2+] decreased by 16.7% relative to the starting concentration. In the microbial systems, precipitation occurred within the mats and was not simply due to the capturing of mineral grains settling out of the water column. Magnesium concentrations decreased by 22.2% and 38.7% in the microbial systems, respectively. Laboratory experiments using natural waters from the Atlin site produced rosettes and flakey globular aggregates of dypingite precipitated in association with filamentous cyanobacteria dominated biofilms cultured from the site, whereas the abiotic control again precipitated

  9. Geomorphology of MODIS-Visible Dust Plumes in the Chihuahuan Desert - Preliminary Results

    NASA Astrophysics Data System (ADS)

    Gill, T. E.; Mbuh, M. J.; Dominguez, M. A.; Lee, J. A.; Baddock, M. C.; Lee, C. E.; Whitehead, S. C.; Rivera Rivera, N. I.; Peinado, P.

    2009-12-01

    We identified 28 days since 2001 when blowing dust impacted El Paso, Texas and dust plumes were visible on NASA MODIS Terra/Aqua satellite images in the surrounding Chihuahuan Desert. Initiation points of >270 individual plumes were located on the MODIS images. Land use/land cover for each point was determined by field work, aerial photography, and/or soil/geological maps, and points were assigned to the geomorphic classes proposed by Bullard et al. (this session). Although dust plume identification is subjective (weak plumes, plumes obscured by clouds, and plumes occurring when the satellites are not overhead will be missed), these data provide preliminary information on the relationship between geomorphology and the initiation of major dust storms in the Chihuahuan Desert. Ephemeral lakes and alluvial low-relief non-incised lands are roughly equal producers of satellite-visible dust plumes in the Chihuahuan Desert. Anthropogenic modification of alluvial floodplains for cropping (primarily in the Casas Grandes and Del Carmen river basins) impacts dust generation, since about 2/3 of alluvial low-relief sites show evidence of agriculture. These agricultural fields are generally fallow during the November- April windy season. Not including agricultural lands, playas represent ~2x the number of sources as low-relief alluvial deposits. Aeolian sand deposits (predominantly coppice dunes and sand sheets overlaying alluvial or lacustrine sediments) account for about 1/7 of the points. These sands may act as erosional agents, providing saltating particles for sandblasting and bombardment of other sediments exposed nearby. Edges of ephemeral lakes are proportionally important sources (~10% of the points), likely due to the convergence of saltating sand, fine lacustrine sediments, and low roughness lengths of playa surfaces. Alluvial fans and alluvial uplands are minor dust sources compared to their overall prevalence in the region. Gobi/gibber/stony deposits are known dust

  10. Integrated hydrogeochemical, isotopic and geomorphological depiction of the groundwater salinization in the aquifer system of Delhi, India

    NASA Astrophysics Data System (ADS)

    Kumar, Manish; Rao, M. Someshwar; Deka, Jyoti Prakash; Ramanathan, AL.; Kumar, Bhishm

    2015-11-01

    exploitation of groundwater, and enhanced evaporation have together resulted in saline playa condition in some part of the region. The scenario was further verified by matching the required condition for the formation of salt pan or playa with the existing geo-morphological conditions of the area. Isotopic results indicate that salinity flushing is possible and proceeds in the areas of freshwater recharge.

  11. Monitoring Changes in Moisture Load Using Elastic Displacements in the Vadose Zone

    NASA Astrophysics Data System (ADS)

    Thrash, C. J.; Murdoch, L. C.; Germanovich, L. N.; Weinberg, A.

    2014-12-01

    Monitoring changes in mass over scales of several meters to hundreds of meters or more has many applications to characterization of the Critical Zone, including assessing changes in soil moisture, erosion or deposition of sediment, and melting or accumulation of snow or ice. A technique has been developed to monitor average changes in mass on those scales using continuous high-resolution measurements of displacement made with a vertical extensometer (called a DELTA extensometer). An increase of mass above the extensometer causes the soil to contract, which causes the extensometer to function similar to a weighing lysimeter. DELTA extensometers have been deployed at field sites near Clemson, South Carolina, and in northern Texas. The extensometers in South Carolina are in saprolite derived from biotite gneiss, whereas the ones in Texas are in clayey silt underlying playas. The instruments are in the vadose zone at depths of 3m to 6m. Signals from co-located extensometers are remarkably similar, demonstrating reproducibility of the technique. The extensometers respond to loading from a person or vehicle, and this load is used to estimate the Young's modulus of soil enveloping the extensometer. Displacement during small to moderate rainfalls is typically linear with the accumulated rain (~0.2 micron/mm of rain, for example). The displacement levels out during large rainfalls, potentially due to the onset of overland flow that would limit the water load during precipitation. This suggests that the onset of overland flow could be evaluated using this technique. Seasonal temperature fluctuations at the soil surface can penetrate to the depths of the extensometers causing displacement from thermal expansion and contraction. Thermal effects account for approximately 100 μm of displacement over an annual cycle at one instrument. It appears that much of the thermal signal can be removed by data analysis. Pore pressure changes in the vicinity of the extensometer can also

  12. Preliminary Results from a Late Pleistocene to Holocene Paleoclimate Study of the Lake Sediment Cores, Northern New Mexico

    NASA Astrophysics Data System (ADS)

    Cedillo, D. N.; Brister, A. R.; LoPresti, C. A.; Maldonado, M.; Pitrucha, R. M.; West, C.; Martinez, E.; Lineline, J.; Petronis, M. S.

    2011-12-01

    activity, these lacustrian systems shrank to their current condition of minor low-volume isolated lakes and numerous playas and pluvial bodies. We hypothesize that sediments from the LVNWR and surrounding playas contain an invaluable and untapped record of late Pleistocene to Holocene climatic change.

  13. Long-term comparison of the fish community in a Costa Rican rocky shore marine reserve.

    PubMed

    Myers, Mark C; Wagner, Jonathan; Vaughan, Christopher

    2011-03-01

    Despite their role in supporting diverse marine fish communities, tropical rocky shores and reefs have attracted less research and fewer targeted conservation efforts compared to coral reefs. We studied fish community composition in Playa Blanca Marine Reserve (9 degrees 40' N - 84 degrees 40' W), a rocky shore site on the central Pacific coast of Costa Rica. We conducted visual surveys of fishes along six strip transects soon after the area was designated a marine reserve in 1995, then again in 2006 following an eleven-year period of complete protection. We recorded a total of 31 406 sightings of 72 species from 30 families. Pomacentrids (42.5%), labrids (16.6%) and haemulids (14.8%) dominated the community, accounting for > 70% of total fish abundance. In comparison to other sites in the region, the fish community was more similar to one reported from Bahia Honda, Panama (7 degrees 50' N - 81 degrees 35 W) than from the geographically more proximate Culebra Bay, Costa Rica (10 degrees 45' N - 85 degrees 43 W). Sixty-one species from 26 families were recorded in 1995; sixty-nine species from 28 families in 2006. Our results suggest that the Playa Blanca Marine Reserve is fulfilling its conservation role. Average fish abundance, species richness and Shannon's index of community diversity were greater in 2006 than 1995, and fish community composition varied significantly within each transect among years. Much of the change in community composition among years resulted from spatial and temporal variation in the abundance of a few dominant species, including Abudefduf troschelli, Thalassoma lucasanum, Chromis atrilobata, and Stegastes flavilatus/acapulcoensis. Of the 48 species/species groups recorded in both years, 37 (77%) were more abundant in 2006 than 1995, and several species recorded as uncommon or rare in 1995 were more frequent and abundant in 2006. Fish community composition and the abundance of some species changed in the reserve over time, but further

  14. Geophysical and Hydrological Characterization of Alluvial Fans in the Valle El Sauz Encinillas, Chihuahua, México.

    NASA Astrophysics Data System (ADS)

    Villalobos-Aragón, A.; Chávez-Aguirre, R.; Osuna-Vizcarra, A.; Espejel-García, V. V.

    2007-05-01

    The Valle El Sauz Encinillas (VESE) is located 92 km north of Chihuahua City, México. Despite being the principal aquifer feeding Chihuahua City, and being flanked by two well studied geological features (Bloque Calera-Del Nido to the West, and the Sierra Peña Blanca to the East), a lack of available hydrogeological data prevails in the valley. The goals of this study are two: 1) geomorphometrical analysis of the sub-basins and alluvial fans, and 2) determination of the alluvial fan geoelectrical units via electrical-resistivity soundings. The Basin and Range system forms a closed sub-basin with a lacustrine basin system in extinction process. The aquifer is located in alluvial Quaternary sediments, with varying granulometry, reaching a thickness of 600 meters at the center of the valley. The biggest alluvial fan in the VESE is located at the Cañón de Santa Clara, and intersects the playa-lake deposits of the Laguna de Encinillas. This fan has a surface of 73.2 km2 and an average slope of 0.437°. The geomorphometrical analysis included the sub-basins, currents, and the fans in the area. These analyses allow a comparison between alluvial fans in the VESE and those in Death Valley, California, USA. The alluvial fans in both areas show a similar behavior in all plots. Twenty electrical resistivity soundings (Schlumberger array, AB/2 distance of 400 m) were performed in the alluvial fan. The basement and four other geoelectrical units were identified in the fan. The geophysical data, granulometric determinations, plus geochemical information of twelve wells in the area were analyzed. These data show how the decrease in granulometry, both frontally and laterally in the fan, results in a rise of the hydraulic conductivity and transmisivity values (water wells in Los Sauces and El Faro). However, both the permeability and the water quality in its distal portion, are affected by the playa lake deposits, the raising ratio of clay-size sediments (and evaporites) in the

  15. Detection and Preliminary Assessment of Source Areas of the 15 December 2003 Dust Storm in the Chihuahuan Desert, Southwestern North America

    NASA Astrophysics Data System (ADS)

    Rivera Rivera, N. I.; Gill, T. E.; Bleiweiss, M. P.; Hand, J. L.; Dominguez A., M.; Ruiz, A.; Perez, A. E.; Emmert, S. P.; Lee, J. A.; Mulligan, K. R.

    2005-12-01

    Dust storms can disperse large quantities of fine aeolian sediment regionally and even globally. These extreme aerosol events frequently originate with multiple dust plumes developing simultaneously over a large region. Dust outbreaks originating in the southwestern USA and northern Mexico seasonally transport aerosols long distances across continental North America. However, dust sources in this region are not well characterized. Remote sensing data can be used to assess the frequency and magnitude of these dust events for potential impacts on climate, visibility and health-related air quality issues. We applied a technique that consists of examining visible spectral bands, as well as difference "split-window" images for far-infrared (far-IR) channels using a variety of satellite imagery (NOAA/GOES/GVAR/Imager, NOAA/POES/AVHRR and NASA/TERRA/MODIS). This technique was used to locate the origin of multiple dust plumes in the Chihuahuan Desert region of the southwestern United States and northwestern Mexico during a significant dust event that occurred on December 15, 2003. After dust sources were identified, we superimposed their locations on Landsat-7 images to assess surface features of these aeolian "hotspots," and visited many of these sites to determine the geomorphology, soil/sediment properties, and land use associated with these dust sources. Dust plumes in the Chihuahuan Desert on 15 December 2003 emanated from several land types, including saline playas, bare desert soils, disturbed/abandoned lands, and agricultural areas. In Mexico, sources included several sites along the edges of pluvial Lake Palomas near the contacts between sand sheets and lacustrine sediments, small dry lake beds (lagunas secas) and several sites in the Casas Grandes river basin in Chihuahua. In the United States, dust emission hotspots included dry, unvegetated saline playas (the White Sands near the E and SE edges of Lake Lucero, New Mexico, and the northern Salt Basin west of the

  16. Fertility determinants in the oil region of Mexico.

    PubMed

    Pick, J B; Tellis, G L; Butler, E W

    1989-01-01

    This study analyzes fertility determinants in the oil region of Mexico, consisting of the states of Veracruz, Tabasco, and Campeche. Data are from the 1980 Mexican census and the unit of analysis is the municipio. The regression models, in which the dependent variables of children ever born and child-woman ratio are examined, reveal religious variables to be most significant, with greater fertility for non-Catholics and persons with no religion than for Catholics. Also of great importance are economic variables. Literacy and urbanization, both "classical" Mexican fertility variables, reduce fertility. There are major differences among three urban/rural and three indigenous language subsamples. Results are discussed vis-a-vis demographic theories and prior research. PMID:2814568

  17. El Planetario Móvil de la Municipalidad de la ciudad de Córdoba

    NASA Astrophysics Data System (ADS)

    Suárez, F. E.; Campos, M.; Goldes, G. V.; Carranza, G. J.; Romero, R.; Juri, H. O.

    Se describen las características y operatoria del nuevo Planetario Móvil. Se trata de un equipamiento de propiedad de la Municipalidad de la Ciudad de Córdoba que es operado por personal y en el predio de la Universidad, en virtud de un convenio suscripto entre ambas instituciones. El planetario consta de una cúpula inflable y de un proyector con programas alternativos que incluyen temas de astronomía, geografía, biología y medio ambiente, entre otros. En la actualidad opera en las instalaciones del Pabellón Argentina de la Ciudad Universitaria y recibe delegaciones escolares de todo el territorio provincial. El Planetario Móvil es parte de un proyecto más amplio de divulgación científica en el cual interactúan la Universidad y el Municipio.

  18. Fertility determinants in the oil region of Mexico.

    PubMed

    Pick, J B; Tellis, G L; Butler, E W

    1989-01-01

    This study analyzes fertility determinants in the oil region of Mexico, consisting of the states of Veracruz, Tabasco, and Campeche. Data are from the 1980 Mexican census and the unit of analysis is the municipio. The regression models, in which the dependent variables of children ever born and child-woman ratio are examined, reveal religious variables to be most significant, with greater fertility for non-Catholics and persons with no religion than for Catholics. Also of great importance are economic variables. Literacy and urbanization, both "classical" Mexican fertility variables, reduce fertility. There are major differences among three urban/rural and three indigenous language subsamples. Results are discussed vis-a-vis demographic theories and prior research.

  19. [The interaction of municipal labor markets in the state of Tabasco: an approximation via the use of gravitational models].

    PubMed

    Juarez, E

    1993-01-01

    Employment is an important factor in state planning and a variable in both economic activity and population. Multiregional methodologies which incorporate territorial variables in functional type analyses may be used to study the interactions between municipal labor markets, helping identify those that should receive priority assistance in developing their sources of employment. This work uses a gravitational model to analyze interactions between the local labor markets of 17 seats of municipios in the state of Tabasco as demonstrated with data from the census of 1990. The working hypothesis was that alternatives for labor market growth are distributed hierarchically in descending order of supply as a function of the size of the economically active population in each locality, the relative participation of the unemployed in each locality, and the distance between the localities. The modeling of interaction between local labor markets is achieved in three stages. First, a gravitational model is adjusted with restrictions in the origins. The next step requires use of the parameters resulting from the first step to predict the number of trips to each destination, as a function of levels of unemployment in each locality producing trips. The third stage consists of predictive application of a gravitational model restricted in both origin and destination to define the magnitude of flows between each point of origin and each point of destination. The general character of the gravitational model is described for each step. The model suggests that the main interactions between local labor markets at the level of seats of municipios are located in the center of the state. Three municipal seats in particular had great potential for labor market growth. A separate system of labor market interaction was observed in the southern part of the state. The coastal zone did not appear to offer an alternative for labor market growth. PMID:12287864

  20. Cesarean birth in the border region: a descriptive analysis based on US Hispanic and Mexican birth certificates.

    PubMed

    McDonald, Jill A; Mojarro Davila, Octavio; Sutton, Paul D; Ventura, Stephanie J

    2015-01-01

    Cesarean birth (CB) is more prevalent in the US-Mexico border region than among all US Hispanics. Comparable data from US and Mexican birth certificates can be used to compare prevalence and identify risk factors on either side of the border. Using 2009 US and Mexican birth certificates, we compared the characteristics of US Hispanic and Mexican CBs in six geographic subgroups: US and Mexican border counties/municipios, US and Mexican non-border counties/municipios and the US and Mexico overall. We also explored cesarean prevalence over time. During 2000-2009, CB rates increased from 22.1 to 31.6 % among US Hispanics and from 25.9 to 37.9 % among Hispanics in the US border region. 2009 rates were 44.5 % in Mexico and 43.1 % in the Mexican border region. In both countries, CB rates were similar for primiparas and multiparas. Higher education, being married and parity >4 were associated with CB in Mexico; being married was associated in the US. Hispanic rates were higher in the US border than non-border region for all age groups. Along the border, cesarean rates for Hispanics were highest in Texas (43.5 %) and neighboring Tamaulipas (49.8 %). Higher cesarean prevalence in Mexico than in US Hispanics, while unexplained, is consistent with high prevalence in some Latin American countries. Higher cesarean prevalence among Hispanics in the US border region than among Hispanics nationwide cannot be explained by maternal age or parity. Medical indications are also unlikely to explain such high rates, which are undesirable for mothers and infants.

  1. [In Process Citation].

    PubMed

    Castillo-Castañeda, Patricia Carolina; Gaxiola-Robles, Ramón; Méndez-Rodríguez, Lía Celina; Labrada-Martagón, Vanessa; Zenteno-Savín, Tania

    2016-01-01

    Introducción: los plaguicidas organoclorados (POC) pueden incrementar la producción de especies reactivas de oxígeno (ERO). Tales efectos pueden ser contrarrestados por el sistema antioxidante, el cual se encuentra también en la leche materna. Objetivo: evaluar los indicadores de estrés oxidativo en leche materna asociados a la presencia de POC y su relación con la ingesta de alimentos marinos. Métodos: la leche materna fue colectada de 108 mujeres lactantes. Los indicadores de estrés oxidativo (actividad enzimática antioxidante, concentración de glutatión, producción de radical superóxido [O 2•- ], concentración de peroxidación de lípidos y carbonilos proteicos) se analizaron por espectrofotometría. Las concentraciones de POC se midieron por cromatografía de gases. Resultados y discusión: la producción de O 2•- no presentó relación significativa con las concentraciones de POC. Se encontraron correlaciones significativas entre las concentraciones de POC y la actividad de las enzimas antioxidantes (actividad de glutatión reductasa [GR] y concentración de aldrín [r = - 0,5], actividad de superóxido dismutasa [SOD] y concentración de α-HCH [r = 0,45]). El daño oxidativo mostró baja correlación con el contenido de POC (r < 0,30, p < 0,05). Es posible que los niveles de POC no sean suficientes para incrementar la producción de O 2•- , ya sea que el incremento en la producción de ERO se deba a especies reactivas diferentes a O 2•- o debido a que la capacidad antioxidante es suficiente para evitar el daño oxidativo en leche materna. Conclusión: los resultados de este estudio sugieren que la dieta marina no es un factor determinante en el nivel de contaminación por POC, ni en el daño oxidativo presente en leche materna. PMID:27238808

  2. [In Process Citation].

    PubMed

    Castillo-Castañeda, Patricia Carolina; Gaxiola-Robles, Ramón; Méndez-Rodríguez, Lía Celina; Labrada-Martagón, Vanessa; Zenteno-Savín, Tania

    2016-03-25

    Introducción: los plaguicidas organoclorados (POC) pueden incrementar la producción de especies reactivas de oxígeno (ERO). Tales efectos pueden ser contrarrestados por el sistema antioxidante, el cual se encuentra también en la leche materna. Objetivo: evaluar los indicadores de estrés oxidativo en leche materna asociados a la presencia de POC y su relación con la ingesta de alimentos marinos. Métodos: la leche materna fue colectada de 108 mujeres lactantes. Los indicadores de estrés oxidativo (actividad enzimática antioxidante, concentración de glutatión, producción de radical superóxido [O 2•- ], concentración de peroxidación de lípidos y carbonilos proteicos) se analizaron por espectrofotometría. Las concentraciones de POC se midieron por cromatografía de gases. Resultados y discusión: la producción de O 2•- no presentó relación significativa con las concentraciones de POC. Se encontraron correlaciones significativas entre las concentraciones de POC y la actividad de las enzimas antioxidantes (actividad de glutatión reductasa [GR] y concentración de aldrín [r = - 0,5], actividad de superóxido dismutasa [SOD] y concentración de α-HCH [r = 0,45]). El daño oxidativo mostró baja correlación con el contenido de POC (r < 0,30, p < 0,05). Es posible que los niveles de POC no sean suficientes para incrementar la producción de O 2•- , ya sea que el incremento en la producción de ERO se deba a especies reactivas diferentes a O 2•- o debido a que la capacidad antioxidante es suficiente para evitar el daño oxidativo en leche materna. Conclusión: los resultados de este estudio sugieren que la dieta marina no es un factor determinante en el nivel de contaminación por POC, ni en el daño oxidativo presente en leche materna.

  3. MICROBIOLOGICAL ASSESSMENT OF LETTUCE SALADS AND ANTIMICROBIAL RESISTANCE OF STAPHYLOCOCCUS SPP.

    PubMed

    Guimarães César, Josi; Madruga Peres, Andriele; Pereira das Neves, Caroline; Tupiniquim Freitas de Abreu, Érica; Fagundes de Mello, Jozi; Nunes Moreira, Ângela; Lameiro Rodrigues, Kelly

    2015-11-01

    Introducción: la procura por estabelecimientos que ofrecen alimentos prontos para consumo ha aumentado, sin embrago, los alimentos disponibles en estos locales pueden estar contaminados con microorganismos patogénicos, pudiendo causar enfermedades transmitidas por alimentos. Objetivos: evaluar la calidad microbiológica de las ensaladas de lechuga en los restaurantes de Pelotas RS Brasil, a través de los recuentos de coliformes termotolerantes, Escherichia coli, Staphylococcus spp. y la detección de Salmonella spp. Resistencia a los antimicrobianos de Staphylococcus spp. también se evalúan. Métodos: fueron colectadas 36 muestras de ensaladas de lechuga en nueve restaurantes y realizada la cuantificación de coliformes termotolerantes, Escherichia coli y Staphylococcus spp. e investigación de Salmonella spp., siguiendo la metodología del Bacteriological Analytical Manual. Los aislados de Staphylococcus spp. fueron sometidos al examen de resistencia a antimicrobianos por el método de difusión con discos. Resultados y discusión: de las 36 muestras de ensalada de lechuga, 61,1% presentaron cuantificación de coliformes termotolerantes superiores a lo permitido por la legislación brasileña, y hubo confirmación de E. coli en 5,6% de las muestras. La cuantificación de Staphylococcus coagulasa positiva representó 5,6% de los aislados y Staphylococcus coagulasa negativa representó 77,8%. Todas las muestras presentaron ausencia de Salmonella spp. De los 30 aislados de Staphylococcus spp. examinados, 56,7% fueron resistentes a penicilina, 46,7% a oxacilina, 26,7% a eritromicina y 23,3% fueron multirresistentes. Conclusión: la calidad microbiológica de las ensaladas de lechuga se mostró inadecuada debido a la presencia de microorganismos patogénicos, y los aislados de Staphylococcus spp. presentaron elevado porcentaje de resistencia antimicrobiana.

  4. Modern and Ancient Extremely Acid Saline Deposits: Terrestrial Analogs for Martian Environments?

    NASA Astrophysics Data System (ADS)

    Benison, Kathleen C.; LaClair, Deidre A.

    2003-11-01

    Extremely acid (pH <1) saline lakes and groundwaters existed in the mid-Permian of the mid-continent of North America. Modern counterparts have been found in acid saline lake systems throughout southern Australia. We compare and contrast the Permian Opeche Shale of North Dakota and Nippewalla Group of Kansas to modern Australian salt lakes in southern Western Australia and in northwest Victoria. With the exception of some minor variations in pH, evaporite mineralogy, and water geochemistry, the Permian and modern systems are similar and characterized by: (1) ephemeral saline continental playas hosted by red siliciclastic sediments, (2) evaporite minerals, including abundant sulfates, (3) Al-Fe-Si-rich waters with low pH values, (4) acidophilic microbes, and (5) paucity of carbonates. The composition of these terrestrial systems is strikingly similar to compositional data returned from the martian surface. Specifically, both Earth and martian systems have high amounts of iron oxides and sulfates, and little, if any, carbonates. We propose that the modern and ancient terrestrial acid saline environments may be good analogs for possible environments on Mars.

  5. Strong Acid Mixture and Sequential Geochemical Arsenic Extractions in Surface Sediments from the Santa Maria La Reforma Coastal Lagoon, Mexico: A Bioavailability Assessment.

    PubMed

    Rivera-Hernández, José R; Green-Ruiz, Carlos

    2016-02-01

    Thirty-three sediment samples were collected from the Santa Maria La Reforma coastal lagoon and digested by way of a strong acid mixture and sequential arsenic (As)-extraction method to determine the arsenic (As) content and bioavailability. The As content was determined by atomic fluorescence spectrometry. In addition, grain-size analyses were performed, and organic carbon, carbonate, and iron (Fe) and manganese (Mn) concentrations were determined. Fe and Mn determination was performed by atomic absorption spectroscopy. A Pearson correlation matrix and As enrichment factors were calculated. Sediment concentrations from Santa Maria La Reforma ranged from 3.6 to 25 µg As g(-1) with an average of 13.4 ± 7.6 µg As g(-1). The highest values were observed in the northern (Playa Colorada), north-central (Mocorito River discharge zone), and southern zones ("El Tule" agricultural drain). Most samples were classified as exhibiting no or minor As enrichment and were lower than the threshold effect level (TEL; 7.24 µg g(-1)) for biota (MacDonald et al. in Ecotoxicology 5:253-278, 1996). Low bioavailable As values (<3 %) were measured in the majority of the sediment. The highest As percentages were associated with the oxyhydroxide fraction (F5). The results indicate that As bioavailability is negligible. PMID:26743199

  6. Paleogeographic and paleotectonic development of Laramide basins of SW Utah

    SciTech Connect

    Goldstrand, P.M. )

    1993-04-01

    Initial Laramide-style deformation in SW Utah began in latest Cretaceous (late Campanian or Maastrichtian) time during deposition of the conglomeratic Canaan Peak Formation (TKcp) which thins onto a broad arch located on the northern Paunsaugunt Plateau (Paunsaugunt upwarp). This NNE-SSW trending upward affected sediment dispersal patterns during the early Paleocene and was the southern basin margin for braided fluvial sediments of the Grand Castle Formation (Tgc). These sediments were shed SE, from the inactive Sevier highlands, as far east as the Table Cliff Plateau. Laramide deformation increased during the late( ) Paleocene, after deposition of the Tgc, with the formation of at least two closed basins. During the late( ) Paleocene, the Johns Valley and Upper Valley anticlines, and Circle Cliff Uplift developed with sediment being shed to the SE, E, and SW into the Pine Hollow basin. During initial development of the Pine Hollow basin, the underlying TKcp and Tgc were reworked into the basal Pine Hollow Formation. Small alluvial fans bounded the basin, grading laterally into low-energy fluvial, playa mudflat, and ephemeral lacustrine environments. The basal Claron Formation represents a broad, closed basin that initially developed during the later Paleocene to the SW of the Pine Hollow basin. The Claron basin was bordered by low relief uplands, fluvial floodplains, and calcrete paleosols to the north and moderate relief uplands to the west and east. Shallow lacustrine deposition occurred to the south. Lacustrine onlap of Laramide structures by middle Eocene suggests cessation of Laramide deformation by this time.

  7. Study of time-lapse processing for dynamic hydrologic conditions. [electronic satellite image analysis console for Earth Resources Technology Satellites imagery

    NASA Technical Reports Server (NTRS)

    Serebreny, S. M.; Evans, W. E.; Wiegman, E. J.

    1974-01-01

    The usefulness of dynamic display techniques in exploiting the repetitive nature of ERTS imagery was investigated. A specially designed Electronic Satellite Image Analysis Console (ESIAC) was developed and employed to process data for seven ERTS principal investigators studying dynamic hydrological conditions for diverse applications. These applications include measurement of snowfield extent and sediment plumes from estuary discharge, Playa Lake inventory, and monitoring of phreatophyte and other vegetation changes. The ESIAC provides facilities for storing registered image sequences in a magnetic video disc memory for subsequent recall, enhancement, and animated display in monochrome or color. The most unique feature of the system is the capability to time lapse the imagery and analytic displays of the imagery. Data products included quantitative measurements of distances and areas, binary thematic maps based on monospectral or multispectral decisions, radiance profiles, and movie loops. Applications of animation for uses other than creating time-lapse sequences are identified. Input to the ESIAC can be either digital or via photographic transparencies.

  8. Oxychlorine Detections on Mars: Implications for Cl Cycling

    NASA Technical Reports Server (NTRS)

    Sutter, B.; Jackson, W. A.; Ming, D. W.; Archer, P. D.; Stern, J. C.; Mahaffy, P. R.; Gellert, R.

    2016-01-01

    The Sample Analysis at Mars (SAM) instrument has detected evolved O2 and HCl indicating the presence of perchlorate and/or chlorate (oxychlorine) in all 11 sediments analyzed to date. The hyperarid martian climate is believed to have allowed accumulation of oxychlorine and assumed chloride contents similar to those in hyperarid terrestrial settings. The linear correlation of oxychlorine and chloride of Gale Crater sediments is low (r (sup 2) equals 0.64). Correlations present in hyperarid Antarctica and the Atacama Desert are attributed to unaltered atmospheric source coupled with minimal redox cycling by biological activity. Terrestrial semi-arid to arid settings have low correlations similar to Gale Crater and are attributed to additional inputs of Cl minus from sea salt, dust, and/or proximal playa settings, and possible reduction of oxychlorine phases during wetter periods. While microbiological processes could contribute to low oxychlorine/chloride correlations on Mars, several abiotic mechanisms are more likely, such as changing oxychlorine production rates with time and/or post-depositional geochemical redox processes that altered the Gale Crater oxychlorine and chloride contents.

  9. Secondary island formation in collisional and collisionless kinetic simulations of magnetic reconnection

    SciTech Connect

    Dayton, William S; Roytershteyn, Vadim; Gary, Peter; Yin, L; Albright, B J; Bowers, K J; Karimabadi, H

    2009-01-01

    The evolution of magnetic reconnection in large-scale systems often gives rise to extended current layers that are unstable to the formation of secondary magnetic islands. The role of these islands in the reconnection process and the conditions under which they form remains a subject of debate. In this work, we benchmark two different kinetic particle-in-cell codes to address the formation of secondary islands for several types of global boundary conditions. The influence on reconnection is examined for a range of conditions and collisionality limits. Although secondary islands are observed in all cases, their influence on reconnection may be different depending on the regime. In the collisional limit, the secondary islands playa key role in breaking away from the Sweet-Parker scaling and enabling faster reconnection. In the collisionless limit, their formation is one mechanism for controlling the length of the diffusion region. In both limits, the onset of secondary islands leads to a time dependent behavior in the reconnection rate. In all cases considered, the number of secondary islands increases for larger systems.

  10. Determination of in-flight AVIRIS spectral, radiometric, spatial and signal-to-noise characteristics using atmospheric and surface measurements from the vicinity of the rare-earth-bearing carbonatite at Mountain Pass, California

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Vane, Gregg; Conel, James E.

    1988-01-01

    An assessment of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) performance was made for a flight over Mountain Pass, California, July 30, 1987. The flight data were reduced to reflectance using an empirical algorithm which compensates for solar, atmospheric and instrument factors. AVIRIS data in conjunction with surface and atmospheric measurements acquired concurrently were used to develop an improved spectral calibration. An accurate in-flight radiometric calibration was also performed using the LOWTRAN 7 radiative transfer code together with measured surface reflectance and atmospheric optical depths. A direct comparison with coincident Thematic Mapper imagery of Mountain Pass was used to demonstrate the high spatial resolution and good geometric performance of AVIRIS. The in-flight instrument noise was independently determined with two methods which showed good agreement. A signal-to-noise ratio was calculated using data from a uniform playa. This ratio was scaled to the AVIRIS reference radiance model, which provided a basis for comparison with laboratory and other in-flight signal-to-noise determinations.

  11. A diatom record of climate and hydrology for the past 200 KA from Owens Lake, California with comparison to other Breat Basin records

    USGS Publications Warehouse

    Bradbury, J.P.

    1997-01-01

    Diatoms from lake sediments beneath Owens Lake playa, Inyo County, California, document a nearly continuous paleolimnological record of climate and hydrologic change since the penultimate glacial-interglacial cycle based on a chronology established by radiocarbon, tephrochronology, and paleomagnetic control. Freshwater planktic diatoms (especially species of Stephanodiscus), plagioclase feldspar-rich sediments with high magnetic susceptibility, and Juniperus-type pollen characterized the penultimate glaciation at Owens Lake. Saline diatoms dominated in the following interglacial period, and there are several episodes during which freshwater planktic diatoms became abundant between 100 and 50 ka that may represent interstadial climatic conditions. Saline diatoms fell to low values after 50 ka, but warm-season Aulacoseira species indicate episodes of significant summer precipitation in the hydrologic balance of Owens Lake prior to the last glacial maximum. By 25 ka, glacial environments were again characterized by abundant Juniperus, plagioclase feldspar, and Stephanodiscus species. Generally and Holocene climates were recorded in Owens Lake by short-term fluctuations of saline and freshwater diatoms, desiccation, and oolitic sediments barren of diatoms. Comparison to paleoclimate records both north and south of Owens Lake suggest a southerly displacement of storm tracks originating from the Aleutian Low during glacial episodes.

  12. Eocene climates, depositional environments, and geography, greater Green River basin, Wyoming, Utah, and Colorado

    SciTech Connect

    Roehler, H.W.

    1993-12-31

    The climates, depositional environments, and geography of Eocene rocks in the greater Green River basin are investigated to determine the origin, mode of deposition, and areal distribution of the Wasatch, Green River, Bridger, and Washakie Formations. The data indicate that Eocene climates ranged from cool temperature to tropical and were affected by both terrestrial and astronomical factors. The terrestrial factors were mainly latitude, altitude, regional geography, tectonism, and volcanism. The astronomical factors are interpreted from reptitious rock sequences in the Wilkins Peak Member of the Green River Formation that record seasonal changes, 21,000 year precession of the equinox cycles, 100,000 year eccentricity cycles, and an undetermined cycle of 727,000 years. Eight depositional environments are identified, discussed, and illustrated by diagrams, columnar sections, and photographs. They are: (1) fluvial, (2) paludal, (3) freshwater lacustrine, (4) saltwater lacustrine, (5) pond and playa lake, (6) evaporite (salt pan), (7) mudflat, and (8) volcanic and fluviovolcanic. The areal distribution of the eight depositional environments in the Wasatch, Green River, Bridger, and Washakie Formations is illustrated by photographs and 13 paleogeographic maps. 76 refs., 90 figs.

  13. Origin of fibrous clays in Tunisian Paleogene continental deposits

    NASA Astrophysics Data System (ADS)

    Zaaboub, Noureddine; Abdeljaouad, Saadi; López-Galindo, Alberto

    2005-12-01

    This paper presents mineralogical and geochemical data from several continental sequences located in Central (Ain Ghréwiss and Kébar) and Central-Southern Tunisia (Selja, Kef Schefeir, Shib, Oum El Kcheb and Haidoudi). These sequences vary in age from Late Palaeocene to Early Oligocene and contain considerable quantities of fibrous clays (up to 75% palygorskite and 90% sepiolite). These clays appear in assocation with carbonates (mainly dolomite), detrital aluminosilicates (illite, Al smectites, mixed-layers illite-smectite and kaolinite), quartz and lesser quantities of gypsum and halite. The textural characteristics observed by electron microscopy, the trace and rare earth elements contents and their distribution in the various mineral phases, together with the isotopic composition of dolomite and fibrous clays, provide good clues as to the genesis of the neoformed minerals. Thus, the sepiolite would have precipitated directly in lacustrine, playa-lake or sebka environments under alkaline conditions, high Si and Mg and low Al activity, and arid to semiarid climate. On the other hand, the palygorskite would have formed by transformation of already existing illite and/or smectite type aluminosilicates in solutions in equilibrium with isotopically heavier and, therefore, more evaporated solutions than the sepiolite.

  14. Low Frequency Turbulence as the Source of High Frequency Waves in Multi-Component Space Plasmas

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.; Krivorutsky, Emmanuel N.; Uritsky, Vadim M.

    2011-01-01

    Space plasmas support a wide variety of waves, and wave-particle interactions as well as wavewave interactions are of crucial importance to magnetospheric and ionospheric plasma behavior. High frequency wave turbulence generation by the low frequency (LF) turbulence is restricted by two interconnected requirements: the turbulence should be strong enough and/or the coherent wave trains should have the appropriate length. These requirements are strongly relaxed in the multi-component plasmas, due to the heavy ions large drift velocity in the field of LF wave. The excitation of lower hybrid waves (LHWs), in particular, is a widely discussed mechanism of interaction between plasma species in space and is one of the unresolved questions of magnetospheric multi-ion plasmas. It is demonstrated that large-amplitude Alfven waves, in particular those associated with LF turbulence, may generate LHW s in the auroral zone and ring current region and in some cases (particularly in the inner magnetosphere) this serves as the Alfven wave saturation mechanism. We also argue that the described scenario can playa vital role in various parts of the outer magnetosphere featuring strong LF turbulence accompanied by LHW activity. Using the data from THEMIS spacecraft, we validate the conditions for such cross-scale coupling in the near-Earth "flow-braking" magnetotail region during the passage of sharp injection/dipolarization fronts, as well as in the turbulent outflow region of the midtail reconnection site.

  15. Nitrous Oxide: A Greenhouse Gas That is Also an Ozone Layer Depleting Gas

    NASA Astrophysics Data System (ADS)

    Reed, S.; Uriarte, M.; Wood, T. E.; Cavaleri, M. A.; Lugo, A. E.

    2014-12-01

    Nitrous oxide, N2O, is the major source of nitrogen oxides in the stratosphere, where these oxides playa critical roles in ozone layer depletion by itself and moderating ozone layer depletion by chlorinated chemicals. Thus N2O plays a complex role in the stratosphere. Nitrous oxide is also a greenhouse gas and it contributes to the radiative forcing of climate. Indeed, it is considered the third most important greenhouse gas next to carbon dioxide and methane. This dual role of nitrous oxide makes it an interesting gas for the atmosphere- it bridges the issue of ozone layer depletion and climate change. Nitrous oxide has both natural and anthropogenic sources. Therefore, one needs to consider this important distinction between natural and anthropogenic sources as well as its role in two related but separate environmental issues. Further, the sources of nitrous oxide are varied and diffuse, which makes it difficult to quantify different sources. However, it is clear that a majority of anthropogenic nitrous oxide comes from food production (including agricultural and animal growth practices), an activity that is at the heart of human existence. Thus, limiting N2O emissions is not a simple task! I will briefly summarize our understanding of these roles of nitrous oxide in the earth's atmosphere and touch on the possible ways to limit N2O emissions.

  16. An astrobiological perspective on Meridiani Planum

    USGS Publications Warehouse

    Knoll, A.H.; Carr, M.; Clark, B.; Des Marais, D.J.; Farmer, J.D.; Fischer, W.W.; Grotzinger, J.P.; McLennan, S.M.; Malin, M.; Schroder, C.; Squyres, S.; Tosca, N.J.; Wdowiak, T.

    2005-01-01

    Sedimentary rocks exposed in the Meridiani Planum region of Mars record aqueous and eolian deposition in ancient dune and interdune playa-like environments that were arid, acidic, and oxidizing. On Earth, microbial populations have repeatedly adapted to low pH and both episodic and chronic water limitation, suggesting that, to a first approximation, the Meridiani plain may have been habitable during at least part of the interval when deposition and early diagenesis took place. On the other hand, the environmental conditions inferred for Meridiani deposition would have posed a challenge for prebiotic chemical reactions thought to have played a role in the origin of life on Earth. Orbital observations suggest that the combination of sulfate minerals and hematite found in Meridiani rocks may be unusual on the martian surface; however, there is reason to believe that acidity, aridity, and oxidizing conditions were broadly distributed on ancient Mars. When these conditions were established and how much environmental heterogeneity existed on early Mars remain to be determined. Because sulfates and iron oxides can preserve detailed geochemical records of environmental history as well as chemical, textural and microfossil signatures of biological activity, Meridiani Planum is an attractive candidate for Mars sample return. ?? 2005 Elsevier B.V. All rights reserved.

  17. Airborne Fraunhofer line discriminator (FLD) luminescence imaging systems and its application to exploration problems

    USGS Publications Warehouse

    Watson, Robert D.; Theisen, Arnold F.; Hemphill, William R.; Barringer, Anthony R.

    1980-01-01

    Experiments with an imaging airborne Fraunhofer line discriminator (FLD) are being conducted to establish the feasibility of delineating the areal extent of luminescent materials on the earth's surface from aircraft and spacecraft. All luminescence measurements are related to a standard set of conditions with rhodamine wt dye used as a reference standard. The FLD has a minimum detectable rhodamine wt concentration of 0.1 parts per billion (ppb) at a signal-to-noise ratio of 5.0. Luminescence, when expressed in a signal-to-noise ratio (R) is related to equivalent ppb rhodamine wt through the relationship ppb=(0.1R-0.4). Luminescent materials imaged from an aircraft altitude of approximately 2400 m above terrain include fluorite in association with molybdenum, Pinenut Mountains, Nevada (R=62.0); mineralized playas, Claunch, New Mexico (R=960.0); uranium and vanadium-bearing outcrops, Big Indian Valley, Utah (R=105.0); uranophane sandstones, Sandia Mountains, New Mexico (R=60.0); phosphate outcrops, Pine Mountain, California (R=76.0); and marine oil slicks, Santa Barbara Channel, California (R=24.0). Correlation between the amount of fluorite in the rocks and soils of the Pinenut Mountains and luminescence, measured by the FLD, is as high as 0.88 at the 95 percent confidence level.

  18. Simulated effects of increased recharge on the ground-water flow system of Yucca Mountain and vicinity, Nevada-California

    USGS Publications Warehouse

    Czarnecki, J.B.

    1984-01-01

    A study was performed to assess the potential effects of changes in future climatic conditions on the groundwater system in the vicinity of Yucca Mountain, the site of a potential mined geologic repository for high-level nuclear wastes. These changes probably would result in greater rates of precipitation and, consequently, greater rates of recharge. The study was performed by simulating the groundwater system, using a two-dimensional, finite-element, groundwater flow model. The simulated position of the water table rose as much as 130 meters near the U.S. Department of Energy 's preferred repository area at Yucca Mountain for a simulation involving a 100-percent increase in precipitation compared to modern-day conditions. Despite the water table rise, no flooding of the potential repository would occur at its current proposed location. According to the simulation, springs would discharge south and west of Timber Mountain, along Fortymile Canyon, in the Amargosa Desert near Lathrop Wells and Franklin Lake playa, and near Furnace Creek Ranch in Death Valley, where they presently discharge. Simulated directions of groundwater flow paths near the potential repository area generally would be the same for the baseline (modern-day climate) and the increased-recharge simulations, but the magnitude of flow would increase by 2 to 4 times that of the baseline-simulation flow. (USGS)

  19. Lithium-bearing rocks of the Horse Spring Formation, Clark County, Nevada

    USGS Publications Warehouse

    Brenner-Tourtelot, E. F.; Glanzman, R.K.

    1978-01-01

    The Horse Spring Formation of Miocene age in Clark County, Nevada, contains as much as 0.5% Li in individual samples. Rock sequences which average 0.1% Li range from 3 m thick near Gold Butte (south of Mesquite, Nev.) to as much as 40 m thick near Lava Butte (east of Las Vegas, Nev.) about 75 km to the west. The lithium-bearing beds are light colored to white and contain hectorite in a dolomite, magnesite, or calcite matrix. Varied amounts of gypsum, halite, celestite, clinoptilolite, quartz, feldspar, biolite and colemanite are also present locally. Hectorite is the only lithium mineral recognized to date. The lithium-rich rocks contain low concentrations of most other minor elements except that boron and strontium are enriched. Rarely, barium, arsenic, and zinc are present in anomalously large amounts. The lithium-enriched part of the Horse Spring Formation was formed from a series of volcanic ashes which were deposited in a playa. Relict volcanic ash is recognizable in thin sections as remnant glass shards and vitroclastic textures. Most of the original glass has been altered to clay minerals, carbonate minerals, or zeolites, presumably through interaction with highly saline pore waters. Abundant evidence of spring activity suggests that thermal waters played a part in releasing the lithium from volcanic materials. ?? 1978.

  20. First occurrence of tetrapod footprints from the continental Triassic of the Sidi Said Maachou area (Western Meseta, Morocco)

    NASA Astrophysics Data System (ADS)

    Hminna, Abdelkbir; Voigt, Sebastian; Klein, Hendrik; Saber, Hafid; Schneider, Jörg W.; Hmich, Driss

    2013-04-01

    The Sidi Said Maachou area in the Moroccan western Meseta preserves a succession, up to 400 m thick, of hitherto poorly studied continental Triassic deposits. Recent detailed geological mapping proposes a lithostratigraphic subdivision of the predominantly red-coloured siliciclastic deposits into three formations. Laminated mudstones and fine-grained sandstones in the upper part of the Oued Oum Er Rbiaa Formation have the most interesting fossil content including plant impressions, rhizoliths, fish scales, and invertebrate and vertebrate traces. These biogenic remains are partially associated with tool marks, microbially induced sedimentary structures, oscillation ripples, desiccation cracks, and halite pseudomorphs, suggesting sedimentation in a playa-like, fluvio-lacustrine system under semiarid conditions. All tetrapod footprints from these beds are assigned to Brachychirotherium parvum and indistinguishable from other occurrences of the ichnogenus in Central Europe and North America. Supposed trackmakers are archosaurs of the crocodile stem-group (Crurotarsi) that were widely spread over Triassic Pangaea. Because Brachychirotherium is only known from Late Triassic (Carnian-Rhaetian) deposits, the same age is attributed to the footprint horizon of the Oued Oum Er Rbiaa Formation. This is the first record of Brachychirotherium on the African continent and the first record of Triassic tetrapod footprints in Morocco outside of the High Atlas.

  1. Airborne Multiangle SpectroPolarimeteric Imager (AirMSPI): Calibration and Comparison with Collocated Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) Data

    NASA Astrophysics Data System (ADS)

    Seidel, F. C.; Diner, D. J.; Bruegge, C. J.; Rheingans, B. E.; Garay, M. J.; Daugherty, B. J.; Chipman, R. A.; Davis, A.

    2014-12-01

    The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) is a pushbroom multiangle spectropolarimetric camera with spectral bands near 355, 380, 445, 470, 555, 660, 865, and 935 nm. Flying on NASAs's high-altitude ER-2 aircraft since 2010, AirMSPI uses dual photoelastic modulator (PEM)-based technology to provide accurate measurements of the Stokes linear polarization parameters Q and U in the 470, 660, and 865 nm bands, providing unique observing capabilities for aerosol, cloud, and surface studies. We describe the methodologies used for radiometric and polarimetric calibration and characterization of the AirMSPI instrument, which make use of a combination of laboratory and vicarious techniques. A 1.65 m integrating sphere and overflights of Ivanpah Playa, NV are used for radiometric calibration. Radiometric cross-comparisons with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), also flying on the ER-2, are used to validate the radiometric scale. For polarimetric calibration, a well-calibrated Polarization State Generator is used to provide known polarimetric inputs. A high-extinction rotating wiregrid polarizer is used to derive polarimetric calibration coefficients for each pixel, and the results are then validated using partially polarized light generated using tilted glass plates. Examples of collocated multiangular, polarimetric imagery from AirMSPI and hyperspectral imagery from AVIRIS will be shown, presenting new opportunities for atmosphere and surface remote sensing.

  2. Long-term vegetation change at a fully protected Sonoran Desert site

    USGS Publications Warehouse

    Turner, R.M.

    1990-01-01

    At MacDougal Crater in the Sierra del Pinacate Reserve, Sonora, Mexico, 3 sources of data were used: a series of exactly matched photographs, begun in 1907; detailed permanent-plot maps, dating from 1959-1960; and an age-distribution analysis of a 170-yr old population of Carnegiea gigantea. The crater vegetation is dominated by the woody perennials Cercidium microphyllum, Encelia farinosa, Prosopis sp. and Larrea tridentata, and the columnar cactus Carnegiea gigantea. Various populations of L. tridentata declined 50-90%, and Cercidium declined 60% during the first half of this century with little or no recruitment since. Carnegiea numbers increased 4-fold over the same period. A 200-fold increase in Prosopis in the playa-like crater center occurred in the early 1970s. Elsewhere on the crater floor, Encelia density increased markedly during the same period from insignificant levels in the early 1960s. Age distribution analysis for the Carnegiea population reveals three major establishment peaks during the 1790-1960 period. The high mortality for some of the species was probably the result of the prolonged drought during 1936-1964. Establishment surges for some appear related to periods of unusually heavy precipitation during certain seasons. -from Author

  3. High-resolution topography along surface rupture of the 16 October 1999 Hector Mine, California (Mw 7.1) from airborne laser swath mapping

    USGS Publications Warehouse

    Hudnutt, K.W.; Borsa, A.; Glennie, C.; Minster, J.-B.

    2002-01-01

    In order to document surface rupture associated with the Hector Mine earthquake, in particular, the area of maximum slip and the deformed surface of Lavic Lake playa, we acquired high-resolution data using relatively new topographic-mapping methods. We performed a raster-laser scan of the main surface breaks along the entire rupture zone, as well as along an unruptured portion of the Bullion fault. The image of the ground surface produced by this method is highly detailed, comparable to that obtained when geologists make particularly detailed site maps for geomorphic or paleoseismic studies. In this case, however, for the first time after a surface-rupturing earthquake, the detailed mapping is along the entire fault zone rather than being confined to selected sites. These data are geodetically referenced, using the Global Positioning System, thus enabling more accurate mapping of the rupture traces. In addition, digital photographs taken along the same flight lines can be overlaid onto the precise topographic data, improving terrain visualization. We demonstrate the potential of these techniques for measuring fault-slip vectors.

  4. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill Hole Data in Yucca Flat, Nye County, Nevada

    USGS Publications Warehouse

    Sweetkind, Donald S.; Drake II, Ronald M.

    2007-01-01

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin including alluvial fan, channel, basin axis, and playa deposits.

  5. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill-Hole Data in Yucca Flat, Nye County, Nevada

    USGS Publications Warehouse

    Sweetkind, Donald S.; Drake II, Ronald M.

    2007-01-01

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill-hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin such as alluvial fan, channel, basin axis, and playa deposits.

  6. Death Valley Lower Carbonate Aquifer Monitoring Program Wells Down gradient of the Proposed Yucca Mountain Nuclear Waste Repository

    SciTech Connect

    Inyo County

    2006-07-26

    Inyo County has participated in oversight activities associated with the Yucca Mountain Nuclear Waste Repository since 1987. The overall goal of these studies are the evaluation of far-field issues related to potential transport, by ground water, or radionuclides into Inyo County, including Death Valley, and the evaluation of a connection between the Lower Carbonate Aquifer (LCA) and the biosphere. Our oversight and completed Cooperative Agreement research, and a number of other investigators research indicate that there is groundwater flow between the alluvial and carbonate aquifers both at Yucca Mountain and in Inyo County. In addition to the potential of radionuclide transport through the LCA, Czarnecki (1997), with the US Geological Survey, research indicate potential radionuclide transport through the shallower Tertiary-age aquifer materials with ultimate discharge into the Franklin Lake Playa in Inyo County. The specific purpose of this Cooperative Agreement drilling program was to acquire geological, subsurface geology, and hydrologic data to: (1) establish the existence of inter-basin flow between the Amargosa Basin and Death Valley Basin; (2) characterize groundwater flow paths in the LCA through Southern Funeral Mountain Range, and (3) Evaluation the hydraulic connection between the Yucca Mountain repository and the major springs in Death Valley through the LCA.

  7. Comparison of inversion models using AIRSAR data for Death Valley, California

    NASA Technical Reports Server (NTRS)

    Kierein-Young, Kathryn S.

    1993-01-01

    Polarimetric Airborne Synthetic Aperture Radar (AIRSAR) data were collected for the Geologic Remote Sensing Field Experiment (GRSFE) over Death Valley, California, USA, in September 1989. AIRSAR is a four-look, quid-polarizaiton, three frequency instrument. It collects measurements at C-band (5.66 cm), L-band (23.98 cm), and P-band (68.13 cm), and has a GIFOV of 10 meters and a swath width of 12 kilometers. Because the radar measures at three wavelengths, different scales of surface roughness are measured. Also, dielectric constants can be calculated from the data. The scene used in this study is in Death Valley, California and is located over Trail Canyon alluvial fan, the valley floor, and Artists Drive alluvial fan. The fans are very different in mineralogic makeup, size, and surface roughness. Trail Canyon fan is located on the west side of the valley at the base of the Panamint Range and is a large fan with older areas of desert pavement and younger active channels. The source for the material on southern part of the fan is mostly quartzites and there is an area of carbonate source on the northern part of the fan. Artists Drive fan is located at the base of the Black Mountains on the east side of the valley and is a smaller, young fan with its source mostly from volcanic rocks. The valley floor contains playa and salt deposits that range from smooth to Devil's Golf course type salt pinnacles.

  8. Estimates of deep drainage rates at the U.S. Department of Energy Pantex Plant, Amarillo, Texas

    SciTech Connect

    Fayer, M.J.; Richmond, M.C.; Wigmosta, M.S.; Kelley, M.E.

    1998-04-01

    In FY 1996, the Pacific Northwest National Laboratory (PNNL) provided technical assistance to Battelle Columbus Operations (BCO) in their ongoing assessment of contaminant migration at the Pantex Plant in Amarillo, Texas. The objective of this report is to calculate deep drainage rates at the Pantex Plant. These deep drainage rates may eventually be used to predict contaminant loading to the underlying unconfined aquifer for the Pantex Plant Baseline Risk Assessment. These rates will also be used to support analyses of remedial activities involving surface alterations or the subsurface injection withdrawal of liquids or gases. The scope of this report is to estimate deep drainage rates for the major surface features at the Pantex Plant, including ditches and playas, natural grassland, dryland crop rotation, unvegetated soil, and graveled surfaces. Areas such as Pantex Lake that are outside the main plant boundaries were not included in the analysis. All estimates were derived using existing data or best estimates; no new data were collected. The modeling framework used to estimate the rates is described to enable future correlations, improvements, and enhancements. The scope of this report includes only data gathered during FY 1996. However, a current review of the data gathered on weather, soil, plants, and other information in the time period since did not reveal anything that would significantly alter the results presented in this report.

  9. Marginal erg facies: A trial approach toward a descriptive classification

    SciTech Connect

    Caputo, M.V. ); Langford, R.P. )

    1991-03-01

    During the late 1970s and early 1980s, sedimentologists began recognizing the margins of eolian sand seas as separate, components which differed from interior sand seas in geometry, extent, and facies. Stratigraphers have now observed these differences in eolian rocks. Erg margins may be grouped in five ways: (1) by associations with extradunal environments-coastal plain, lacustrine, periglacial, marine (tidal flat, coastal sabkha, beach, and lagoon), and arid alluvial (alluvial fan, fluvial, playa, inland sabkha); (2) by allocyclic controls-eustasy, plate tectonism, and climate; (3) by autocyclic controls-local tectonism, topography, vegetation, hydrology, structure, sediment source and supply, and wind regime; (4) by geographic position-upwind, downwind, and along-wind margins; and (5) by sedimentary facies-texture and architecture. In contrast with erg interiors, erg margins are characterized by smaller, less complex dune-forms related to thinner sand accumulation; elementary dune architecture; more vegetation and bioturbation; high occurrence of sand sheet, zibar, and serir facies; expansive, low-relief interdunes with widely distributed dunes; and a greater proportion of interbedded extradunal deposits. Some of the published studies on ancient eolian systems have identified erg margin facies that have been influences by marine and arid alluvial processes. Few reports have described lacustrine-eolian and periglacial-eolian interactions. This study is an attempt to organize known features of modern and ancient erg margins into a scheme based on erg margin controls.

  10. Ediacaran in Uruguay: Facts and controversies

    NASA Astrophysics Data System (ADS)

    Aubet, Natalie R.; Pecoits, Ernesto; Heaman, Larry M.; Veroslavsky, Gerardo; Gingras, Murray K.; Konhauser, Kurt O.

    2014-11-01

    The Ediacaran of Uruguay has been regarded as containing a significant geological and paleontological record, which would make these successions critical to unraveling diverse aspects regarding the assembly of southwestern Gondwana and to understanding the conditions surrounding the rise of animal life in a period punctuated by drastic paleoenvironmental changes. However, a review of currently available data leads to the conclusion that, although variable, the stratigraphy, distribution and age of these units remain ambiguous. The same is true for existing basin models and tectonic evolution, which show different and sometimes contradicting supporting evidence. Here, we propose that the Ediacaran record consists of the Maldonado Group (Playa Hermosa, Las Ventanas and San Carlos formations), and the Tacuarí, Barriga Negra, Rocha and Sierra de Aguirre formations. The Arroyo del Soldado Group (Yerbal, Polanco Limestones and Cerro Espuelitas formations) and the Arroyo de la Pedrera Group (Piedras de Afilar and Cerro Victoria formations) were likely deposited between 700 and 1000 Ma. The best available radiometric age constraints indicate intense magmatic-tectonic activity occurred between 600 and 560 Ma, incompatible with previous models suggesting a stable, Atlantic-type passive margin on this portion of southwestern Gondwana. Further research is needed in order to firmly establish a consistent litho- and chronostratigraphic framework; particularly, before attempting any regional or global correlation, and inferences on global paleoenvironmental and paleobiological events.

  11. Sand injectites at the base of the Coconino Sandstone, Grand Canyon, Arizona (USA)

    NASA Astrophysics Data System (ADS)

    Whitmore, John H.; Strom, Ray

    2010-10-01

    In the Grand Canyon, large tabular and wedge shaped sand-filled cracks commonly occur at the base of the Coconino Sandstone, penetrating downward into the coarse siltstones of the Hermit Formation. All previous workers have casually identified the vertical sand-filled cracks as desiccation cracks. Until now, they have never been studied. Cracks and their associated features were found and examined at thirty locations; and it was found that they have characteristics difficult to explain using desiccation mud cracks or large playa cracks as a model. Instead, it was found the cracks have features commonly found in clastic dikes and sand injectites. Some lateral sand bodies associated with the cracks have clastic sill-like characteristics. Liquefaction and injection of the basal Coconino into the Hermit is indicated by 1) macroscopic and microscopic banding (flow structures) within the cracks, 2) bedded sandstone clast breccias in structureless sandstone lenses at the base of the Coconino, 3) lateral sand bodies which are connected to the vertical cracks, 4) a zoned depth distribution of cracks about the Bright Angel Fault zone, 5) insufficient clay mineralogy and particle size for the Hermit to crack by desiccation, 6) preferred orientation of the cracks roughly perpendicular to the Bright Angel Fault zone and several other features. Caution should be exercised when interpreting sand-filled cracks as desiccation features (i.e., "mud cracks"), even if the interpretation fits well with accepted paleoenvironmental models.

  12. Dark and Bright Albedo Changes in the Wake of a Titan Rainstorm

    NASA Astrophysics Data System (ADS)

    Barnes, Jason W.; Buratti, B. J.; Turtle, E. P.; Bow, J.; Dalba, P. A.; Perry, J.; Rodriguez, S.; LeMouelic, S.; Baines, K. H.; Sotin, C.; Lorenz, R. D.; Malaska, M. J.; McCord, T. B.; Clark, R. N.; Jaumann, R.; Hayne, P. O.; Nicholson, P. D.; Soderblom, J. M.; Soderblom, L. A.

    2012-10-01

    Turtle et al. (2011) previously announced large-scale surface changes in Titan's tropics following a 2010 September cloudburst event. Those changes were areas that had darkened, and the darkening was attributed to surface wetting by rain. Here we will discuss the results of continued monitoring of the darkened areas by Cassini VIMS and ISS. These new observations show that instead of reverting to their previous state, the rain-darkened areas instead brightened beyond their original albedos starting a few months after the cloudburst event. The brightening was unexpected, and spectra show that it occurs in each of Titan's atmospheric wavelength windows. The brightened spectra show some similarity to he heretofore unique signature of Xanadu. The areas slowly revert to their original spectra over a period of a year. The two hypotheses that we have not eliminated involve (1) volatile frosts resulting from evaporative cooling of rain-derived surface methane that later sublime, (2) deposition of a thin surface layer of very-fine-grained particles (similar to terrestrial playa lakes) that degrade due to aeolean erosion. Future calculations and observations will serve to constrain the mechanism that drives the brightening.

  13. Climate change impacts on leatherback turtle pelagic habitat in the Southeast Pacific

    NASA Astrophysics Data System (ADS)

    Willis-Norton, Ellen; Hazen, Elliott L.; Fossette, Sabrina; Shillinger, George; Rykaczewski, Ryan R.; Foley, David G.; Dunne, John P.; Bograd, Steven J.

    2015-03-01

    Eastern Pacific populations of the leatherback turtle (Dermochelys coriacea) have declined by over 90% during the past three decades. The decline is primarily attributed to human pressures, including unsustainable egg harvest, development on nesting beaches, and by-catch mortality. In particular, the effects of climate change may impose additional stresses upon already threatened leatherback populations. This study analyzes how the pelagic habitat of Eastern Pacific leatherbacks may be affected by climate change over the next century. This population adheres to a persistent migration pattern; following nesting at Playa Grande, Costa Rica, individuals move rapidly through equatorial currents and into foraging habitat within the oligotrophic South Pacific Gyre. Forty-six nesting females were fitted with satellite tags. Based on the turtle positions, ten environmental variables were sampled along the tracks. Presence/absence habitat models were created to determine the oceanographic characteristics of the preferred turtle habitat. Core pelagic habitat was characterized by relatively low sea surface temperatures and chlorophyll-a. Based on these habitat models, we predicted habitat change using output from the Geophysical Fluid Dynamics Laboratory prototype Earth System Model under the Special Report on Emissions Scenario A2 (business-as-usual). Although the model predicted both habitat losses and gains throughout the region, we estimated that overall the core pelagic habitat of the Eastern Pacific leatherback population will decline by approximately 15% within the next century. This habitat modification might increase pressure on a critically endangered population, possibly forcing distributional shifts, behavioral changes, or even extinction.

  14. Ground water flow in a desert basin: challenges of simulating transport of dissolved chromium.

    PubMed

    Andrews, Charles B; Neville, Christopher J

    2003-01-01

    A large chromium plume that evolved from chromium releases in a valley near the Mojave River was studied to understand the processes controlling fate and migration of chromium in ground water and used as a tracer to study the dynamics of a basin and range ground water system. The valley that was studied is naturally arid with high evapotranspiration such that essentially no precipitation infiltrates to the water table. The dominant natural hydrogeologic processes are recharge to the ground water system from the Mojave River during the infrequent episodes when there is flow in the river, and ground water flow toward a playa lake where the ground water evaporates. Agricultural pumping in the valley from the mid-1930s to the 1970s significantly altered ground water flow conditions by decreasing water levels in the valley by more than 20 m. This pumping declined significantly as a result of dewatering of the aquifer, and water levels have since recovered modestly. The ground water system was modeled using MODFLOW, and chromium transport was simulated using MT3D. Several innovative modifications were made to these modeling programs to simulate important processes in this ground water system. Modifications to MODFLOW include developing a new well package that estimates pumping rates from irrigation wells at each time step based on available drawdown. MT3D was modified to account for mass trapped above the water table when the water table declines beneath nonirrigated areas and to redistribute mass to the system when water levels rise.

  15. Great Salt Lake, and precursors, Utah: The last 30,000 years

    USGS Publications Warehouse

    Spencer, R.J.; Baedecker, M.J.; Eugster, H.P.; Forester, R.M.; Goldhaber, M.B.; Jones, B.F.; Kelts, K.; McKenzie, J.; Madsen, D.B.; Rettig, S.L.; Rubin, M.; Bowser, C.J.

    1984-01-01

    Sediment cores up to 6.5 m in length from the South Arm of Great Salt Lake, Utah, have been correlated. Radiocarbon ages and volcanic tephra layers indicate a record of greater than 30,000 years. A variety of approaches have been employed to collect data used in stratigraphic correlation and lake elevation interpretation; these include acoustic stratigraphy, sedimentologic analyses, mineralogy, geochemistry (major element, C, O and S isotopes, and organics), paleontology and pollen. The results indicate that prior to 32,000 year B.P. an ephemeral saline lake-playa system was present in the basin. The perennial lake, which has occupied the basin since this time, rose in a series of three major steps; the freshest water conditions and presumably highest altitude was reached at about 17,000 year B.P. The lake remained fresh for a brief period, followed by a rapid increase in salinity and sharp lowering in elevation to levels below that of the present Great Salt Lake. The lake remained at low elevations, and divided at times into a north and south Basin, until about 8,000 year B.P. Since that time, with the exception of two short rises to about 1290 m, the lake level has remained near the present elevation of 1280 m. ?? 1984 Springer-Verlag.

  16. Potential effects of climate change on aquatic ecosystems of the Great Plains of North America

    USGS Publications Warehouse

    Covich, A.P.; Fritz, S.C.; Lamb, P.J.; Marzolf, R.D.; Matthews, W.J.; Poiani, K.A.; Prepas, E.E.; Richman, M.B.; Winter, T.C.

    1997-01-01

    The Great Plains landscape is less topographically complex than most other regions within North America, but diverse aquatic ecosystems, such as playas, pothole lakes, ox-bow lakes, springs, groundwater aquifers, intermittent and ephemeral streams, as well as large rivers and wetlands, are highly dynamic and responsive to extreme climatic fluctuations. We review the evidence for climatic change that demonstrates the historical importance of extremes in north-south differences in summer temperatures and east-west differences in aridity across four large subregions. These physical driving forces alter density stratification, deoxygenation, decomposition and salinity. Biotic community composition and associated ecosystem processes of productivity and nutrient cycling respond rapidly to these climatically driven dynamics. Ecosystem processes also respond to cultural effects such as dams and diversions of water for irrigation, waste dilution and urban demands for drinking water and industrial uses. Distinguishing climatic from cultural effects in future models of aquatic ecosystem functioning will require more refinement in both climatic and economic forecasting. There is a need, for example, to predict how long-term climatic forecasts (based on both ENSO and global warming simulations) relate to the permanence and productivity of shallow water ecosystems. Aquatic ecologists, hydrologists, climatologists and geographers have much to discuss regarding the synthesis of available data and the design of future interdisciplinary research. ?? 1997 by John Wiley & Sons, Ltd.

  17. The ICDP-Hominin Sites and Paleolakes Drilling Project (HSPDP): new data from the Chew Bahir site in Ethiopia

    NASA Astrophysics Data System (ADS)

    Leng, Melanie; Dean, Jonathan; Asrat, Asfawossen; Cohen, Andrew; Foerster, Verena; Just, Janna; Klasen, Nicole; Lamb, Henry; Schäbitz, Frank; Trauth, Martin; Viehberg, Finn; Wagner, Bernd

    2016-04-01

    There are currently few long, continuous, Pleistocene records from East Africa, meaning it has been difficult to establish the relative influence of low- versus high-latitude forcing on East African climate and climatic conditions at the time of anatomically modern human origin and subsequent dispersal. We have been attempting to address these gaps in our knowledge by analysing lake sediments taken from Chew Bahir, an area of playa mudflats in southern Ethiopia close to the site of the oldest-known anatomically modern human fossils at Omo-Kibish. In March 2014, Chew Bahir was cored to a depth of ~40 metres, and the resulting sediment sequence is estimated to cover the last ~115ka. In December 2014, a nearby site was drilled to a depth of ~280 metres as part of the International Continental scientific Drilling Programme - Hominin Sites and Paleolakes Drilling Project (HSPDP). The oxygen and carbon isotope composition of endogenic calcite and other data from these cores will be presented. The data show some significant changes in water balance variability, the period prior to 70ka appears very unstable with some significant periods of drought and flood. Between 70-20ka the lake was stable and evaporative. The last 20ka years was wetter.

  18. Sample collection of virulent and non-virulent B. anthracis and Y. pestis for bioforensics analysis

    SciTech Connect

    Hong-geller, Elizabeth; Valdez, Yolanda E; Shou, Yulin; Yoshida, Thomas M; Marrone, Babetta L; Dunbar, John

    2009-01-01

    Validated sample collection methods are needed for recovery of microbial evidence in the event of accidental or intentional release of biological agents into the environment. To address this need, we evaluated the sample recovery efficiencies of two collection methods -- swabs and wipes -- for both non-virulent and virulent strains of B. anthracis and Y. pestis from four types of non-porous surfaces: two hydrophilic surfaces, stainless steel and glass, and two hydrophobic surfaces, vinyl and plastic. Sample recovery was quantified using Real-time qPCR to assay for intact DNA signatures. We found no consistent difference in collection efficiency between swabs or wipes. Furthermore, collection efficiency was more surface-dependent for virulent strains than non-virulent strains. For the two non-virulent strains, B. anthracis Sterne and Y. pestis A1122, collection efficiency was approximately 100% and 1 %, respectively, from all four surfaces. In contrast, recovery of B. anthracis Ames spores and Y. pestis C092 from vinyl and plastic was generally lower compared to collection from glass or stainless steel, suggesting that surface hydrophobicity may playa role in the strength of pathogen adhesion. The surface-dependent collection efficiencies observed with the virulent strains may arise from strain-specific expression of capsular material or other cell surface receptors that alter cell adhesion to specific surfaces. These findings contribute to validation of standard bioforensics procedures and emphasize the importance of specific strain and surface interactions in pathogen detection.

  19. Precipitation and lake-level changes in the West and Midwest over the past 10,000 to 24,000 years. Final report

    SciTech Connect

    Webb, T. III; Street, F.A.; Howe, S.

    1980-02-04

    The goal of the research described in this report is to document the climatic variability over the past 10,000 to 20,000 years in areas in which sites may be designated for the burial of nuclear wastes. Three separate data sets were studied, and the results are presented in three chapters. The first data set consisted of radiocarbon dates documenting past changes in lake levels in lakes and playas in the western United States. The sites were mapped where water levels were higher than the levels today and were presented in a table telling what evidence is available at each site. The lake-level fluctuations for the past 24,000 years at sites in the West were also mapped and time series for these fluctuations at four sites were presented. The second data set was a selection of the published radiocarbon-dated pollen diagrams from the western United States. These data are a valuable source of climatic information and complement the geological evidence of lake-level fluctuations in the West. A table is presented that gives the location, elevation, and number of radiocarbon dates for each site. The third data set was a set of fossil pollen data from 20 sites in the upper Midwest. These data were calibrated in terms of precipitation changes over the past 10,000 years, and maps are presented of the estimated precipitation changes between 10,000 and 7000 years ago and between 7000 years ago and today.

  20. Biological survey of Naval Petroleum Reserve No. 2 (Buena Vista), Kern County, California

    SciTech Connect

    O'Farrell, T.P.; Sauls, M.L.

    1987-06-01

    A field survey of Naval Petroleum Reserve No. 2, Kern County, California, was conducted to determine the distribution and relative abundance of endangered species and other wildlife. Of the 343 San Joaquin kit fox dens found in 40 sections, 33 were observed by surveyors in transit and 310 were found along transects. Of the latter, 264 were typical subterranean dens and 46 were atypical dens in man-made structures. Estimated density of dens was 28.8 +- 4.4 per square mile; relative density was 9.2/1000 acres. The number of typical dens observed per section was inversely correlated with the number of petroleum wells per section (intensity of development). Atypical dens were usually found to be in pipes or pipe culverts and were positively correlated with density of wells. Relative densities of black-tailed jackrabbits (41.9/1000 acres) and desert cottontails (17.1/1000 acres), preferred prey for foxes, were high compared with densities reported on other public lands. Most (81%) of the 19 blunt-nosed leopard lizards were observed in six adjacent sections located in the gentle foothills near Buena Vista Lake playa. Most (86%) of the 275 giant kangaroo rat burrow systems were observed in ten sections containing flat, relatively undeveloped terrain in and around upper Buena Vista Valley. San Joaquin antelope ground squirrels were the second most commonly observed diurnal vertebrate: 761 observations in 45 sections. A total of 6740 observations of 61 species of wildlife were made.