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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. Salt Playas of the Bolivian Altiplano

    NASA Image and Video Library

    2003-01-08

    In the high plateau of southwestern Bolivia, two large salt deserts, or playas, are located between the eastern and western Andes. NASA Terra spacecraft depicted the playas on January 16, 2002 and January 3, 2003.

  3. Geochronology of Playas Lake, NM and Willcox Playa, Arizona

    NASA Astrophysics Data System (ADS)

    Kowler, A.

    2008-12-01

    Playa lake basins contain valuable archives of late Quaternary paleoclimatic conditions in the southwestern United States. Previous research on lake basins in the region has revealed several pluvial intervals post- dating the last full glacial period; however, the timing of these intervals can only be assessed through the collective analysis of individual lake-level histories. While previous studies of lake core sediments have provided baseline data for climate modelers, the accuracy of most lake chronologies has been limited by uncertainties associated with 14C reservoir corrections. Further, most studies have used the sedimentological, chemical, and biological characteristics of lake sediments to infer relative lake-level. In contrast, radiocarbon-dated shoreline deposits-although unfortunately rare-can provide accurate information about the timing and duration of high stands, as well as a record of absolute lake-level during these events. Recent investigations of shoreline and spring sediments from playa lake basins provide preliminary geochronological and paleoenvironmental information about effective precipitation in the Southwest during the late Pleistocene and early Holocene. The results of ongoing investigations at Willcox Playa, Arizona, and Playas lake, New Mexico, are presented here.

  4. 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.

  5. 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.

  6. Precipitation response by Qom Playa, Iran

    NASA Astrophysics Data System (ADS)

    Gillespie, A. R.; Enzel, Y.; Mushkin, A.; Abbott, E.; Amit, R.; Crouvi, O.

    2006-12-01

    Playas, or dry lakes, are common landforms in the arid and semi-arid parts of the world. They integrate hydrologic and sedimentologic responses to climate at all temporal scales (individual storm to millennial) and, equally important, at regional to basin scales. Playas are also a source or sink for dust, depending on the water-sediment interaction. Therefore, playas are potentially useful in mapping and understanding global and regional climate changes, and geologic studies on individual playas have been useful in paleoclimate studies. The main difficulties in constructing and/or using such records lie in the lack of measured hydrological data, simply because most are located in remote areas such as the Sahara, and central and west Asia. High- resolution multispectral satellite remote sensing has been conducted for most of the Earth since 1973 and the archives are publicly available. These images offer a means of examining current and historical regional variations in precipitation, independent of point measurements, and thus may be especially valuable where there are few weather-monitoring programs. However, spectral images are not simple to use and may be impractical because of cost and availability of expertise. We provide here an example how the immense remote-sensing database provides a >40-yr history of surface-wetting events in playas that complements NCEP reanalysis weather data and recent TRMM rainfall data, which are modeled from cloud-top temperatures. Our analysis takes advantage of the temporal length of the archive to detect changes in hydrological conditions in Qom playa, south of Tehran (Iran), based on the spectral changes that attend wetting and drying of salts and clay and changes in the depth of standing water. High-resolution Landsat and Terra images with ~16-day repeats show variations in hydrology as patterns of playa wetting and drying that we tested against precipitation data. We found 259 Landsat cloud-free archived images of Qom Playa

  7. Evolution of playa basins on the Texas High Plains--Evidence from playa-basin fills

    SciTech Connect

    Hovorka, S.D. . Bureau of Economic Geology)

    1993-02-01

    Heterogeneous sediments in playa basins document the evolution of shallow depressions on the Texas High Plains surface through the late Quaternary. The suite of sediments encountered in playa-lake basins differs from the typical lithologies of the Blackwater Draw Formation in upland areas. The upland Blackwater Draw Formation has red-brown clayey silt containing root casts, well-developed soil fabrics, and abundant pedogenic carbonate nodules. Cores drilled in playa basins encountered a repetitive suite of gray clay, well-sorted fine to medium sand, and laminated sand and silt associated with clay drapes and beds of pedogenic calcite pebbles. The gray clay was deposited in ephemeral lakes similar to modern playa lakes. Small clams and drab colors extending downward from these deposits demonstrate ponding. Soil fabrics, soil slickensides, deep clay-filled cracks, and root tubules within the clayey beds indicate desiccation and exposure of the lake floor. Well-sorted sand layers represent episodic migration of sand sheets across the playa. Laminated sand and silt beds are interpreted as delta deposits that formed at the mouths of draws. Minimal soil formation indicates relatively rapid deposition during delta progradation. The suite of playa sediments interfingers with upland Blackwater Draw facies, documenting the temporal equivalence of playa and upland deposition and expansion and contraction of the lake within the playa basin. Complex patterns of oxidation, reduction, and precipitation and dissolution of calcite document the interaction between ground water and sediments.

  8. Pattern formation in Salt Playa

    NASA Astrophysics Data System (ADS)

    Lasser, Jana; Goehring, Lucas; Nield, Joanna

    2017-04-01

    Salt Playa, or crusts, often exhibit polygonal salt-ridge patterns with a diameter of roughly 1 m. Several mechanisms, like cracking or wrinkling of the surface crust have been discussed, but none of these can explain the scale of the observed patterns. We investigate a theory where we link the crust pattern to buoyancy-driven flows in the porous ground beneath them. In this model, salinity gradients arise due to evaporation at the ground surface. These gradients lead to the formation of convection cells, much like the convection caused by temperature gradients. The spatial scaling of these convection rolls significantly depends on the evaporation rate, while the onset of convection is controlled by the permeability of the soil. Here we will show a link between surface salt patterns and subsurface dynamics. We investigate the onset of convection, the scaling of convection cells, and the formation of salt crusts in a sandy soil confined to a Hele-Shaw cell in analogue experiments and link subsurface concentration gradients to surface crust patterns by means of a field study. The aim of the experiments and the field study is to explore how porous media convection can affect salt crust patterns in arid environments.

  9. Methods of Determining Playa Surface Conditions Using Remote Sensing

    DTIC Science & Technology

    1987-10-08

    Superiors 18 2•0 5. Coyote 0 6. Troy 17- 7. Lucerne 1 • 8. Soggy 0 2 14 15 16 9. Melville S 4 5010. Bristol 350 0 13 11. Cadiz Barstow* 6 * 12. Danby ...of saline deposits on wet soft playa, Danby Playa (original scale 1:30,000). Figure 5. Giant desiccation cracks, Lucerne Playa (left); surface...channels in soft surface, Danby Playa (right). Figure 6. Salt evaporation ponds on wet surface, Cadiz Playa. HAL, 400 700 1000 1300 800 2900 2200 2500

  10. 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.

  11. Playa basin development, southern High Plains, Texas and New Mexico

    SciTech Connect

    Gustavson, T.C. ); Holliday, V.T. )

    1992-01-01

    More than 20,000 playa basins have formed on fine-grained eolian sediments of the Quaternary Blackwater Draw and Tertiary Ogallala Formations on the High Plains of TX and NM. Numerous hypotheses have been proposed for the development of playa basins: (1) subsidence due to dissolution of underlying Permian bedded salt, (2) dissolution of soil carbonate and piping of clastic sediment into the subsurface, (3) animal activity, and (4) deflation. Evidence of eolian processes includes lee dunes and straightened shorelines on the eastern and southern margins of many playas. Lee dunes, which occur on the eastern side of ca 15% of playa basins and contain sediment deflated from adjacent playas, are cresentic to oval in plain view and typically account for 15--40% of the volume of the playa basin. Quaternary fossil biotas and buried calcic soils indicate that grasslands and semi-arid to aid climatic conditions prevailed as these basins formed. Evidence of fluviolacustrine processes in playa basins includes centripetal drainage leading to fan deltas at playa margins and preserved deltaic and lacustrine sediments. Playa basins expanded as fluvial processes eroded basin slopes and carried sediment to the basin floor where, during periods of minimal vegetation cover, loose sediment was removed by deflation. Other processes that played secondary roles in the development of certain playa basins include subsidence induced by dissolution of deeply buried Permian salt, dissolution of soil carbonate and piping, and animal activity. Two small lake basins in Gray County, TX, occur above strata affected by dissolution-induced subsidence. Dissolution of soil carbonate was observed in exposures and cores of strata underlying playa basins. Cattle, and in the past vast numbers of migrating buffalo, destroy soil crusts in dry playas, making these sediments more susceptible to deflation, and carry sediment out of flooded playas on their hooves.

  12. 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

  13. 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

  14. 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.

  15. Mysterious Roving Rocks of Racetrack Playa

    NASA Image and Video Library

    2017-09-27

    In some cases, the trail starts narrow and gets wider, as in this photo. Photo credit: NASA/GSFC/Leva McIntire/LPSA intern To read a feature story on the Racetrack Playa go to: www.nasa.gov/topics/earth/features/roving-rocks.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

  16. 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.

  17. Observation of playa salts as nuclei in orographic wave clouds

    NASA Astrophysics Data System (ADS)

    Pratt, Kerri A.; Twohy, Cynthia H.; Murphy, Shane M.; Moffet, Ryan C.; Heymsfield, Andrew J.; Gaston, Cassandra J.; Demott, Paul J.; Field, Paul R.; Henn, Tobias R.; Rogers, David C.; Gilles, Mary K.; Seinfeld, John H.; Prather, Kimberly A.

    2010-08-01

    During the Ice in Clouds Experiment-Layer Clouds (ICE-L), dry lakebed, or playa, salts from the Great Basin region of the United States were observed as cloud nuclei in orographic wave clouds over Wyoming. Using a counterflow virtual impactor in series with a single-particle mass spectrometer, sodium-potassium-magnesium-calcium-chloride salts were identified as residues of cloud droplets. Importantly, these salts produced similar mass spectral signatures to playa salts with elevated cloud condensation nuclei (CCN) efficiencies close to sea salt. Using a suite of chemical characterization instrumentation, the playa salts were observed to be internally mixed with oxidized organics, presumably produced by cloud processing, as well as carbonate. These salt particles were enriched as residues of large droplets (>19 μm) compared to smaller droplets (>7 μm). In addition, a small fraction of silicate-containing playa salts were hypothesized to be important in the observed heterogeneous ice nucleation processes. While the high CCN activity of sea salt has been demonstrated to play an important role in cloud formation in marine environments, this study provides direct evidence of the importance of playa salts in cloud formation in continental North America has not been shown previously. Studies are needed to model and quantify the impact of playas on climate globally, particularly because of the abundance of playas and expected increases in the frequency and intensity of dust storms in the future due to climate and land use changes.

  18. 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

  19. Mysterious Roving Rocks of Racetrack Playa

    NASA Image and Video Library

    2017-09-27

    Some of the moving rocks are large. This one is about 10 inches tall. Researchers in the late 1960s and early 1970s documented the movements of one very large rock that they named Karen. (The two men named all the rocks after women.) They estimated that Karen weighed 700 pounds. Credit: NASA/GSFC/Maggie McAdam To read a feature story on the Racetrack Playa go to: www.nasa.gov/topics/earth/features/roving-rocks.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

  20. Mysterious Roving Rocks of Racetrack Playa

    NASA Image and Video Library

    2017-09-27

    To investigate the rocks and trails, the interns collect many kinds of data, such as trail length, width, and depth; rock size; magnetic and radiation measurements; and GPS coordinates. The students also photograph the rocks, the trails and the cracks in the mud within and outside the trails. Photo credit: NASA/GSFC/Maggie McAdam To read a feature story on the Racetrack Playa go to: www.nasa.gov/topics/earth/features/roving-rocks.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

  1. 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.

  2. Microbial Nitrogen and Sulfur Cycles at the Playa and Playa-lake Deposits of White Sands National Monument, New Mexico

    NASA Astrophysics Data System (ADS)

    Glamoclija, M.; Fogel, M. L.; Steele, A.

    2011-12-01

    A deflationary basin, Alkali Flat, of White Sands National Monument holds active playas and a playa lake, which allows for an excellent comparison of these different (hyper)saline habitats. Playa lakes are commonly studied as extreme hypersaline environments, however from our data, less studied playa sediments and coarse selenite crystals showed to be more biologically challenging environments. The Flat contains dome structures composed of coarse selenites, an alternative newly discovered microbial habitat. A comparison of environmental physicochemical conditions and molecular biology was used to determine the characteristics of microbial habitats and communities and to decipher nodes of nitrogen and sulfur cycles. On Mars, the presence of sulfate rich playa deposits has been suggested for the deposits discovered by the Opportunity rover at Meridiani Planum. Recently, it has been suggested that the playa settings extended to a larger, Arabia Terra, zone of groundwater upwelling. The study of terrestrial analogue site with playa settings, such as Alkali Flat from New Mexico, provides an analogue system to explore and characterize the proposed habitable zones and their potential biosignatures. At White Sands, playa lake deposits held up to 55wt.% of water within the surface mirabilite crust, bottom layers composed of sulfates, clay, halite, and carbonates had less water. The lake deposits hold the only setting with reducing chemistry that was detected in the layers beneath the crust (with 3.42:1 ammonium (NH4) over nitric oxides (NO)). Playa sediments were 10 times drier than the playa lake deposits and had patchy surface crust of halite and gypsum. Selenite crystals were the driest among studied habitats (0.16wt.% H2O). Playa sediments and selenites contained 9.49 and 3.9 times more NO than NH4, suggesting importance of nitrification processes in these settings. Nitrogen fixation genes were detected only in playa lake deposits. A variety of ammonium oxidation genes

  3. ACCELERATED DEFLATION ON MESQUITE LAKE PLAYA, MOJAVE DESERT

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    Mesquite Lake Playa is a significant sediment source for high levels of dust in Las Vegas, Nevada. Located just south of the California-Nevada border, Mesquite Lake Playa is a gypsiferous playa characterized by scattered yardangs and sand sheets, and is partly ringed by high mesquite-stabilized dunes. A rapidly expanding deflation basin has been found on the southeastern part of the playa. The deflation basin is visible on a 2002 Landsat image, but it is not present on 1989 or earlier aerial photographs. By 2006, the basin was four times larger than in 2002 and nearly 59,000 m3 of sediment, calculated by a GIS analysis, had been excavated by the wind. The deflation basin has exposed late Pleistocene paludal sediment with good preservation of delicate surface features (e.g. mud cracks and tracks) that are quickly eroded after exposure to the wind. Wind measurements recorded over one year on the playa reveal that sand-moving winds occur only about 6 percent of the time with the greatest concentration of windstorms taking place during April and May. Approximately a third of the eroded sediment was likely added to the dust flux exiting this basin. The recent rapid expansion of the 1-2-m deep basin is attributed to lowering of the water table and exposure of dry, unconsolidated, gypsum-rich sediment. Loss of soil moisture reduces cohesion of the playa sediment, rendering it more susceptible to wind erosion. Wind-tunnel tests indicate that wind will transport eight times as much of the newly exposed, gypsum-rich sediment compared with the cohesive sediment of the undisturbed playa surface. Measured water levels on three old wells marginal to the playa show that the 2009 water table is 3-4 m lower than during the 1960s. The current water table is at 4-5 m beneath the playa, which may be lower than at any time since the Pleistocene. The recent water-level decline may be the result of ground-water extraction and a regional drought that began in the late 1990s. Continued

  4. Spatial distribution and morphology of sediments in Texas Southern High Plains playa wetlands

    USDA-ARS?s Scientific Manuscript database

    Playas are depressional geomorphic features on the U.S. High Plains. About 20,000 Southern High Plains playa wet¬lands serve as runoff catchment basins, which are thought to be focal points of Ogallala aquifer recharge. Sediments in playas can alter biodiversity services, impede aquifer recharge, an...

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

    USDA-ARS?s Scientific Manuscript database

    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...

  6. La importancia de la protección de las playas

    EPA Pesticide Factsheets

    Las playas son una parte importante de la vida en Estados Unidos. Las playas ofrecen un sinnúmero de beneficios para el medio ambiente, actividades recreativas y la economía local. Aprenda la importancia de las playas y cómo protegerlas.

  7. 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.

  8. 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.

  9. 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).

  10. Healthy Municipios in Latin America.

    PubMed

    Restrepo, H E; Llanos, G; Contreras, A; Rocabado, F; Gross, S; Suárez, J; González, J

    1995-09-01

    This article describes the Healthy Municipios movement in Latin America and gives examples of some PAHO projects that could become demonstration projects. The Healthy Municipios movement was established in the early 1990s. The movement aims to promote healthy municipalities according to objectives set forth in the 1987 Ottawa Charter on Health Promotion, the 1992 Declaration of Bogota, and the 1993 Caribbean Health Promotion Charter. The movement is a joint effort of government, the health sector, and the community in promoting health locally. Key features of the movement are its creativity, variety, political strength, and adaptation to local conditions. Technical cooperation serves the purpose of facilitating information exchange and promotes the use of modern techniques of analysis and scientific and technical information. All projects shared the following common features: initiation by the local community with strong political commitment, intersectoral organizational structure, widespread community mobilization and participation, problem solving activities, and a recognizable leader. Pioneering projects include the Comprehensive Project for Cienfuegos, Cuba; the Health Manizales, Colombia; the Network in Mexico; Baruta and El Hatillo, Venezuela; Valdivia, Chile; and San Carlos Canton, Costa Rica. It is concluded that these projects and most others aim to assure equity. These efforts are important for placing health on the political agenda and implementing healthy policies. The Valdivia project, for example, serves a population of about 120,000 in the urban city of Valdivia, the semi-urban area, and rural areas. The project was officially sanctioned by the President of Chile on World Health Day in 1993. Progress was reported in mass communication and school-based programs. Attention was directed also to prevention of risk factors for noncommunicable diseases and to the problem of traffic accidents.

  11. 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

  12. Evaluation of Radionuclide Mobilization and Redistribution during Playa Lake Formation on the Frenchman Flat Playa, Nevada Nuclear Security Site

    NASA Astrophysics Data System (ADS)

    LeFebre, K.; Hershey, R. L.; Decker, D.

    2011-12-01

    An array of programs has been investigating the environmental impacts of nuclear testing at the Nevada National Security Site since 1973. Because of above-ground testing in the 1950s, ground surface contamination on surface soils and neutron activation of nearby soil and materials has occurred from atmospheric deposition. Other concerns include redistribution of surface-deposited radionuclides by runoff, infiltration, wind, and other mechanical means. The goal of this study is to identify the potential for radionuclide mobilization and redistribution by chemical reactions during sporadic flooding of the Frenchman Flat Playa. Radionuclide mobility is dependent on a number of factors and might occur when the playa becomes flooded. Several geochemical processes that could mobilize and redistribute radionuclides include dissolution of playa minerals, precipitation of new minerals in different locations, sorption of radionuclides onto suspended or colloidal materials, and infiltration of soluble radionuclides to the subsurface environment. Following the heavy winter precipitation that flooded the playa in 2010 and 2011, playa-lake water samples were collected from easily accessed locations and analyzed for major ions, TDS, hydrogen and oxygen isotopes and radionuclides; suspended/precipitated materials were characterized by XRD; and, water-soil geochemical reactions were modeled. The geochemical software PHREEQC was used to model the soil-water evolution of the playa-lake water over time. Inputs to model simulations include precipitation chemistry, major-ion chemistry from water samples, mineralogy from XRD analysis of sediments, and radionuclides from spectroscopic measurements or literature values. Model simulations were constructed in a series of steps so that important water-soil chemical reactions could be determined and the changes in the playa water chemistry quantified as a result of these reactions. As the sequence of steps is taken, the simulations become

  13. Hydraulic gradient and dust emissivity along a playa to distal fan transect

    NASA Astrophysics Data System (ADS)

    Caldwell, T. G.; Sweeney, M.; Bacon, S. N.; McDonald, E.

    2009-12-01

    Distal alluvial fans along the margins of playas in the desert southwest, as well as the playas themselves, are subjected to severe temporal changes in groundwater levels. Soil moisture decreases with elevation above the playa floor where groundwater levels control both soil moisture and salinity. A series of measurements were conducted along transects of a wet playa (Soda Lake, California) and a dry playa (Silver Lake; California) to quantify changes in PM10) emissions, in addition to soil physical and chemical properties. The relatively high moisture content at the playa surface of Soda Lake is controlled by a perennial shallow ground water system that promotes the precipitation and wicking of evaporates and the formation of soluble salt crusts. In contrast, Silver Lake playa is underlain by a deep ground water system, therefore the playa surface remains dry throughout the year, except for unseasonably wet winters when flooding occurs of the playa surface during inundation events. Measurements were taken along linear transects across a diverse range of playa features ranging from the playa floor to distal fans using the Portable In-Situ Wind Erosion Lab (PI-SWERL), electromagnetic induction, and soil sampling. Results indicate that dust emissivity of undisturbed soils at a friction velocity (u*) of 0.56 m s-1 increases substantially at the playa fringe (3.53 ± 1.44 mg m-2 s-1) compared to the relatively higher distal alluvial fans (0.13 ± 0.08 mg m-2 s-1) and lower emission on the playa surfaces of either the silt crust of Silver Lake playa (<0.08 mg m-2 s-1) or salt crust of Soda Lake playa (<0.03 mg m-2 s-1). Soil chemistry shifts from stiff NaCl dominated salt-rich crusts on playas to hard CaSO4 gypsic-rich crusts on distal fans. The area between these landforms, the silt-rich playa fringe, is subjected to transient groundwater and surface water influx resulting in monovalent bicarbonate (HCO3-) salts which disperse clays and creates an area of high

  14. Land use and conservation reserve program effects on the persistence of playa wetlands in the High Plains.

    PubMed

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

    2014-04-15

    Watershed cultivation and subsequent soil erosion remains the greatest threat to the service provisioning of playa wetlands in the High Plains. The U.S. Department of Agriculture's (USDA) Conservation Reserve Program (CRP) plants perennial vegetation cover on cultivated lands including playa watersheds, and therefore, the program influences sediment deposition and accumulation in playas. Our objective was to measure the effects of the CRP on sediment deposition by comparing sediment depth and present/historic size characteristics in 258 playas among three High-Plains subregions (northern, central, and southern) and the three dominant watershed types: cropland, CRP, and native grassland. Sediment depth and resultant volume loss for CRP playas were 40% and 57% lower than cropland playas, but 68% and 76% greater than playas in native grassland. Playas in CRP had remaining volumes exceeding those of cropland playas. Grassland playas had nearly three times more original playa volume and 122% greater wetland area than CRP playas. Overall, playas were larger in the south than other subregions. Sediment depth was also three times greater in the south than the north, which resulted in southern playas losing twice as much total volume as northern playas. However, the larger southern playas provide more remaining volume per playa than those in other subregions. The results of this study demonstrate the importance of proper watershed management in preserving playa wetland ecosystem service provisioning in the High Plains. Furthermore, we identify regional differences in playas that may influence management decisions and provide valuable insight to conservation practitioners trying to maximize wetland services with limited resources.

  15. 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.

  16. Biophysical controls over concentration and depth distribution of soil organic carbon and nitrogen in desert playas

    NASA Astrophysics Data System (ADS)

    McKenna, Owen P.; Sala, Osvaldo E.

    2016-12-01

    Playa wetlands are important areas of soil organic carbon and nutrient storage in drylands. We conducted this study to assess how catchment biophysical variables control soil organic carbon and nitrogen in playas and how playas function differently than upland ecosystems. We found that playa organic carbon and nitrogen corresponded primarily with catchment vegetation cover and secondarily with catchment area, slope, and soil texture. The effect of increased organic matter production associated with high catchment vegetation cover overshadowed the potential effect of reduced run-on. We also found soil carbon and nitrogen profiles to be significantly shallower in playas than uplands. This trend is correlated with evidence of sedimentation and shallow-rooted plants in playas. Upland soils had a deeper carbon and nitrogen profile, which correlated with organic matter being generated by deeply rooted vegetation. In playas, C:N ratios remained constant through depth but in uplands, C:N ratios increased through depth. We found evidence that differences in rooting depth distributions and soil texture may explain these C:N variations between uplands and playas. In uplands, clay concentration increased with depth, whereas in playas, clay concentration did not change with depth, which highlighted the important role of sedimentation in these ecosystems. Our results suggest that small changes in playa catchment vegetation cover in response to climate change or grazing intensity would greatly impact playa soil organic carbon and nitrogen stocks. This effect would be due to the playa soils dependence on allochthonous organic matter and the large upland area that drains into playas.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. A modern subtropical playa complex: Salina de Ambargasta, central Argentina

    NASA Astrophysics Data System (ADS)

    Zanor, Gabriela A.; Piovano, Eduardo L.; Ariztegui, Daniel; Vallet-Coulomb, Christine

    2012-04-01

    Salina de Ambargasta is a playa located at mid latitudes in central Argentina (29 °S-64 °W). Because of its hydrological behaviour, this playa complex can be subdivided into a closed system "sensu-stricto" and an "open-like system" due to the presence of a seasonal outflow. Geomorphological and sedimentological features enable the separation of the Ambargasta playa into well-defined western, eastern and northern zones, where aeolian processes, groundwater supply and surface inflow, respectively, define distinctive sedimentary environments and typical processes of deposition. The following depositional settings were recognized: (1) alluvial fan; (2) sandflat; (3) springs; (4) dunes and palaeo-dune field; (5) dry mudflat; (6) capillary mudflat; (7) ephemeral saline lake (includes saline mudflat and salt pan). The dry mudflat is present at the highest topographical zone, where the groundwater influence is less important and only intermittent ponds are present. In the capillary mudflat, evaporite sedimentation is limited to the development of efflorescence by evaporative pumping. The ephemeral saline lake, placed in the lowermost topographical region, alternates cycles of lake expansion and contraction responding to inter-annual hydrological variability as well as to seasonal variability. Lake expansion takes place during early austral summer (December-March), while continuous evaporation of brine leads to the growth of halite crystals during late summer. Sodium chloride-type brines result from both chemical fractionation as evaporation increases and salt dissolution. The isotopic compositions of surficial and underground waters (δ18O and δ2H) indicate that lake waters become isotopically enriched during summer when evaporation plays a significant role in the playa complex.

  2. 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

  3. 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.

  4. Dust Generation Resulting from Desiccation of Playa Systems: Studies on Mono and Owens Lakes, California

    NASA Astrophysics Data System (ADS)

    Gill, Thomas Edward

    1995-01-01

    Playas, evaporites, and aeolian sediments frequently are linked components within the Earth system. Anthropogenic water diversions from terminal lakes form playas that release fugitive dust. These actions, documented worldwide, simulate aeolian processes activated during palaeoclimatic pluvial/interpluvial transitions, and have significant environmental impacts. Pluvial lakes Russell and Owens in North America's Great Basin preceded historic Mono and Owens Lakes, now desiccated by water diversions into dust-generating, evaporite -encrusted playas. Geochemical and hydrologic cycles acting on the Owens (Dry) Lake playa form three distinct crust types each year. Although initial dust production results from deflation of surface efflorescences after the playa dries, most aerosols are created by saltation abrasion of salt/silt/clay crusts at crust/ sand sheet contacts. The warm-season, clastic "cemented" crust is slowest to degrade into dust. If the playa surface is stabilized by an unbroken, non-efflorescent crust, dust formation is discouraged. When Mono Lake's surFace elevation does not exceed 1951 meters (6400 feet), similar processes will also generate dust from its saline lower playa. Six factors--related to wind, topography, groundwater, and sediments--control dust formation at both playas. These factors were combined into a statistical model relating suspended dust concentrations to playa/lake morphometry. The model shows the extent and severity of Mono Lake dust storms expands significantly below the surface level 6376 feet (1943.5 meters). X-ray diffraction analysis of Mono Basin soils, playa sediments, and aerosols demonstrates geochemical cycling of materials through land, air and water during Mono Lake's 1982 low stand. Soils and clastic playa sediments contain silicate minerals and tephra. Saline groundwater deposited calcite, halite, thenardite, gaylussite, burkeite and glauberite onto the lower playa. Aerosols contained silicate minerals (especially

  5. Preliminary results of dust emission data from Yellow Lake Playa, West Texas, USA

    USDA-ARS?s Scientific Manuscript database

    We investigated the relationship between groundwater and dust emission rates at Yellow Lake, a saline “wet” playa in West Texas with a long history of wind erosion. Deflation of the playa surface has generated lunettes composed of silt-clay aggregates and gypsum. Saltation sensors indicate that most...

  6. Dust Emissions from Undisturbed and Disturbed, Crusted Playa Surfaces: Cattle Trampling Effect

    USDA-ARS?s Scientific Manuscript database

    Dry playa lake beds can be a significant source of fine dust emissions during high wind events in arid and semiarid landscapes. The physical and chemical properties of the playa surface control the amount and properties of the dust emitted. In this study, we use a field wind tunnel to quantify the...

  7. A hydrological simulation of the water regime in two playa lakes located in southern Spain

    NASA Astrophysics Data System (ADS)

    Miguel, Rodriguez-Rodriguez; Malte, Schilling

    2014-08-01

    The subject of this paper is the detailed hydrological simulation of two playa lakes located in southern Spain from January 2011 to March 2012 on a daily basis. These playas are placed over a 400-km 2 shallow aquifer, which is exposed to an increasing stress caused by agricultural activities, mainly olive grove plantations. The objective of the paper is to elaborate a detailed numeric model that simulates the water regime of each playa lake on a daily scale. The simulation is compared to measured water level (WL) data of the playas in order to characterize the groundwater-surface interactions. The ultimate objective of this paper is to assess the environmental impact of the increasing anthropogenic water consumption within the area of research. The results of the GW-surface interaction were very consistent with previous works. One of the playa lakes is groundwater-dependent and the other one is presumably a perched playa lake. The GW discharge of the former playa (214 mm) during the research period stands in sharp contrast to no regional GW discharge in the latter. Water level data prove that the hydrological year (2011-2012) had a very negative water budget. The evapotranspiration estimation was almost as high as double the sum of the precipitation, the run-off, and the groundwater discharge. The simulation of an anthropologically altered water regime proves that water retrieval has a harmful impact on the WL of the playa lakes as well as on the aquifer.

  8. Dust emissions from undisturbed and disturbed, crusted playa surfaces: cattle trampling effects

    USDA-ARS?s Scientific Manuscript database

    Dry playa lake beds can be significant sources of fine dust emission. This study used a portable field wind tunnel to quantify the PM10 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 ...

  9. Linear Dunes and Playas, Simson Desert, South Australia, Australia

    NASA Image and Video Library

    1991-12-01

    This image of abstract shapes is comprised numerous subparallel, very long, orange colored linear dunes and patchy grey dry lakes (playas). The dunes are aligned north to south in the great central basin of Astralia (27.0S, 138.0E). The regularity of the dunes is created by the winds blowing from the south. As the dunes advance, jaged edges on the south side of each dry lake are formed while the north side is eroded smooth by the wind and water.

  10. 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.

  11. 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.

  12. A change-detection application on the evolution of Kahak playa (South Khorasan province, Iran)

    NASA Astrophysics Data System (ADS)

    Rezaei Moghaddam, Mohammad Hossein; Saghafi, Mahdi

    2006-12-01

    Kahak salt playa in South Khorasan province of Iran, have special geomorphological characteristics by the presence of ephemeral saline lakes, wetlands, salt crusts, surface accumulations of salt and zones of patterned ground. Salt crusts in the soil surface are unique in the region and have laminated horizons in the playa soil. Soil-surface salt accumulations are dominated by NaCl and gypsum. It has been found that distribution of chemical soluble is not uniform across the playa landscape, and this result influences on the variety form of patterned ground. In this study, the percent changes in some of the chemical elements such as NaCl, gypsum and also brine extent have been calculated in the playa. Indicating changes in Kahak salt playa is the main aim of this study by using remote sensing and GIS techniques. In this paper, techniques such as spectral un-mixing, maximum likelihood classification, band rationing, fuzzy classification and correlation relationships are discussed. This contribution presents modeling of temporal and spatial changes of salinity and playa developing using combined approaches that incorporate different data-fusion and data-integration techniques for two periods of date. Furthermore, percent changes in the surface-patterned ground of the playa have been calculated using texture and pattern analysis of the PCA1. Results have revealed that, in the playa developing, chemical materials such as sodium, NaCl, gypsum and also brine extent are positively correlated with each other and the most increased changes are related to gypsum and the most decreased changes are related to the NaCl. Also changes in the amount of agricultural area in the playa-lakes margin, show low effects in the desertification process.

  13. Racetrack and Bonnie Claire: southwestern US playa lakes as analogs for Ontario Lacus, Titan

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.; Jackson, Brian; Hayes, Alex

    2010-03-01

    We note the geomorphological and meteorological processes at Racetrack Playa, Death Valley National Park, as analogs for those at Ontario Lacus on Titan. Although Ontario is ˜50× larger, the planforms of the two features are nearly identical, both are extremely flat, and are in environments where infrequent rainfall occurs against a climate, where evaporation exceeds precipitation. While the famous moving rocks on the Racetrack Playa may be exceptional on the Earth, the lower gravity and thicker atmosphere may render wind-induced rock transport comparatively common on Titan. Nearby Bonnie Claire Playa also provides field insights into the interpretation of remote sensing data from Titan.

  14. 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.

  15. Ice rafts not sails: Floating the rocks at Racetrack Playa

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.; Jackson, Brian K.; Barnes, Jason W.; Spitale, Joe; Keller, John M.

    2011-01-01

    We suggest that the existence of many of the rock-carved trails at Racetrack Playa in Death Valley National Park is predominantly due to the effect of arbitrarily weak winds on rocks that are floated off the soft bed by small rafts of ice, as also occurs in arctic tidal beaches to form boulder barricades. These ice cakes need not have a particularly large surface area if the ice is adequately thick—the ice cakes allow the rocks to move by buoyantly reducing the reaction and friction forces at the bed, not by increasing the wind drag. The parameter space of ice thickness and extent versus rock size for flotation is calculated and found to be reasonable. We demonstrate the effect with a simple experiment.

  16. 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

  17. Green River iaminites: does the playa-lake model really invalidate the stratified-lake model

    SciTech Connect

    Boyer, B.W.

    1982-06-01

    Proponents of the playa-lake model have proposed deposition of most of the Green River Formation microlaminated carbonates (including oil shales) in lakes that were not perennially stratified (meromictic). However, there is a variety of evidence favoring a meromictic depositional environment: (1) close similarity of much of the lamination to varves in modern meromictic lakes, (2) evidence that hydrologic events favoring development of meromixis (chemical stratification) occurred prior to deposition of major accumulations of oil shale, (3) mutually exclusive distribution of fossil nekton (especially fish) and normal lacustrine benthos (including mollusks), and (4) analogy with a Quaternary playa that became a meromictic lake following increased inflow. The playa-lake model is untenable for the typical fish-bearing, kerogen-rich microlaminated sediments. These laminites were probably deposited in a large ectogenic meromictic lake - a chemically stratified lake that formed when increased fresh-water inflow ''drowned'' a saline playa complex.

  18. 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.

  19. Impact of One Hundred Years of Owens Lake Playa Dust on Nearby Alluvial Soils

    NASA Astrophysics Data System (ADS)

    Quick, D. J.; Reheis, M. C.; Stewart, B. W.; Chadwick, O.

    2009-12-01

    Owens Lake Playa in Owens Valley, California has been one of the largest point sources of PM-10 dust in the United States for about 100 years. Dust composition and deposition rates on the lakebed and downwind of the lakebed have been measured since 1991 by the USGS. These data circumscribe the amount and composition of dust likely to be incorporated into nearby soils. Our research documents the incorporation of playa dust in soils relative to distance from the playa by using strontium isotopes as a provenance tracer. There are distinct contrasts in trace element chemistry, strontium isotopic composition and particle size among the granitic parent material, the playa sediments and the regional dust fall. These contrasts allow us to develop quantitative estimates of the role of salts and fines in the soil profiles and to calculate the proportions derived from different sources. We sampled soils of similar texture (and inferred age) on alluvial fans derived from Sierra Nevada granites along the north-northwest—south-southeast valley axis and performed water and acid leaches on these samples to determine soluble salt concentrations as well as their strontium concentrations and isotope ratios. Early results demonstrate salt concentrations 2-8 X higher in soils adjacent to and immediately north of the playa, as well as a clear strontium isotope signature from the playa. We have thus far quantified playa dust inputs to soils in four locations near the playa and determined, in detail, the input and impact of playa dust to one soil in the Alabama Hills just north of the playa. We used this profile as an example of the possible effect on other surrounding soils over the next 100 years if the playa dust is not significantly mitigated. The Alabama soils have high measures of electrical conductivity (EC; the horizons range from about 250 µS/cm to more than 1100 µS/cm) compared to all other soils sampled, an average pH of 10.0 and a sodium adsorption ratio (SAR) greater than

  20. Diversity of Salmonella serovars in feedyard and nonfeedyard playas of the Southern High Plains in the summer and winter.

    PubMed

    Purdy, Charles W; Straus, David C; Clark, R Nolan

    2004-01-01

    To compare Salmonella isolates cultured from feedyard and nonfeedyard (control) playas (ie, temporary shallow lakes) of the Southern High Plains. Water and muck (sediment) samples were obtained from 7 feedyard playas and 3 nonfeedyard playas in the winter and summer. Each water and muck sample was enriched with sulfur-brilliant-green broth and incubated in a shaker at 37 degrees C for 24 hours. A sample (100 mL) of the incubated bacterial-enriched broth was then mixed with 100 mL of fresh sulfur-brilliant-green enrichment broth and incubated in a shaker at 37 degrees C for 24 hours. After the second incubation, a swab sample was streaked on differential media. Suspect Salmonella isolates were further identified by use of biochemical tests, and Salmonella isolates were confirmed and serovar determinations made. Salmonella isolates were not recovered from the 3 control playas. Seven Salmonella enterica serovars were isolated from 5 of 7 feedyard playas in the summer, and 13 S. enterica serovars were isolated from 7 of 7 feedyard playas in the winter. In the summer, 296 isolates were cultured, and 47 were Salmonella organisms. In the winter, 288 isolates were cultured, and 171 were Salmonella organisms. Results indicated that feedyard playas are frequently contaminated with many Salmonella serovars. These pathogens should be considered whenever feedyard managers contemplate the use of water from these playas. Water from feedyard playas should not be used to cool cattle in the summer or for dust abatement.

  1. 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.

  2. The water balance equations in saline playa lakes: comparison between experimental and recent data from Quero Playa Lake (central Spain)

    NASA Astrophysics Data System (ADS)

    Sánchez-Moral, S.; Ordóñez, S.; Benavente, D.; García del Cura, M. A.

    2002-04-01

    The Quero Playa Lake is an ephemeral saline playa lake located in the La Mancha region of central Spain. In this study, a daily monitoring of the brine physical properties, water activity, brine depth and main climatic parameters was simultaneously carried out together with determining the precipitation sequence of minerals. Field data were compared with the results of simulating the water evaporation in an environmental chamber. In this simulation, a similar hydrochemical composition for the saline lake was used, and the main climatic parameters, temperature and humidity, were controlled. The water balance equation for saline lakes has usually been described using the Wood and Sanford equation [Econ. Geol., 85(1990) 1226-1235]. Our experimental results required us to revise the water balance equation for the brine depth variations (d h/d t), that may be expressed as follows: {dh }/{dt }=p 1+k {A B}/{A L}+S I-S O-ξ-H+D, where p (mm) is the precipitation; k is the drainage coefficient of the lake; AL is the lake surface; AB is the drainage basin surface; SI and SO are the contribution of influent and effluent seepage to the depth of brine in the lake. The term ξ is the evaporation/condensation, defined as ξ= kpW( aW-RH), where k is the mass transfer coefficient (Dalton's equation); pW is the water pressure in equilibrium with the air; aW is the water activity of the brine; RH is the relative humidity. The other terms: H and D, correct the brine depth loss or/and gain a consequence of hydrated saline mineral precipitation and early diagenetic hydration/dehydration reactions. As a consequence of the above, we suggest that the water balance equation for saline lakes can be an important consideration in the interpretation of their evolution. The precipitation of hydrated saline minerals and the early diagenetic dehydration/hydration reactions imply changes in the d h/d t curves. As a result, the interpretation of the sequence of primary saline minerals in older

  3. 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.

  4. Playa lake and sheetflood deposits of the Upper Cretaceous Jindong Formation, Korea: Occurrences and palaeoenvironments

    NASA Astrophysics Data System (ADS)

    Paik, I. S.; Kim, H. J.

    2006-05-01

    Lake model of the Upper Cretaceous Jindong Formation in Korea was established on the basis of sedimentological and palaeobiological records of the playa lake and sheetflood deposits and their palaeoenvironmental implications. The playa lake and sheetflood deposits of the Jindong Formation are characterized by the common presence of traces of vanished evaporites, complicated polygonal desiccation cracks and rainprints, the pedogenic carbonate development, and the preservation of invertebrate traces and dinosaur and bird tracks. The traces of vanished evaporites including halite and sulphate evaporite occur as evaporite pseudopmorphs and moulds. The occurrence of all of the evaporite minerals as traces suggests that flooding stages persisted much longer than evaporation and desiccation stages. Invertebrates, birds, and dinosaurs inhabited the playa lake environment of the Upper Cretaceous Jindong Lake. The Jindong Lake formed by the combination of humid source area and arid depositional site due to an orographic effect in fault-bounded basin. Extensive development of the playa lake and sheetflood deposits with evaporite mineral casts and very limited association of shoreline deposits in the Jindong Formation are characteristic of closed lake, and the Jindong Lake is compared to a lake formed in partly drained closed basin. The aggradation of mudflat deposits indicates continued subsidence of the basin and continuation of an underfilled lake basin. The Jindong Lake expanded and stabilized as a playa lake surrounded by dry to saline mudflats, and palaeoclimate and subsidence rates changed little throughout the period of the Jindong Lake development.

  5. 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.

  6. 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.

  7. 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.

  8. Comparison of Infiltration Flux in Playa Lakes in Grassland and Cropland Basins, Southern High Plains of Texas

    USDA-ARS?s Scientific Manuscript database

    Playas are the dominant wetland type on the Southern High Plains (SHP) of Texas and capture runoff during periods of heavy rainfall. Observing the hydrologic functions of playa wetlands is important to evaluate their ecological services, which include encouragement of species biodiversity and recha...

  9. 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.

  10. Satellite Imagery Measures of the Astronomically Aligned Megaliths at Nabta Playa

    NASA Astrophysics Data System (ADS)

    Brophy, T. G.; Rosen, P. A.

    2003-12-01

    Astronomically aligned megalithic structures described in field reports (Wendorf, F. and Malville, J.M., The Megalith Alignments, pp.489-502 in Holocene Settlement of the Egyptian Sahara, Vol.I, 2001.) are identified in newly acquired georectified 60 cm panchromatic satellite imagery of Nabta Playa, southern Egypt. The satellite images allow refinement, often significant, of the reported locations of the megaliths. The report that the primary megalithic alignment was constructed to point to the bright star Sirius, circa 4,820 BC, is reconsidered in light of the satellite data, new field data, radiocarbon, lithostratigraphic and geochronologic data, and the playa sedimentation history. Other possible archaeoastronomical interpretations are considered for that alignment, including the three stars of Orion's Belt circa 6,270 BC that are also implicated in the small Nabta Playa `calendar circle'. Other new features apparent in the satellite imagery are also considered.

  11. 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.

  12. Tectonic constraints and hydrological functioning in several playa-lakes from southern Spain

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rodríguez, Miguel; Moral, Francisco; Díaz-Azpiroz, Manuel; Pérez-Valera, Fernando

    2013-04-01

    We have selected three main wetland systems located in southern Spain to describe the tectonic factors that have given rise to the formation of closed depressions originating playa - lakes in a semi arid climate context. The three wetlands are located in the provinces of Córdoba, Seville and Cádiz (Andalusia). The low-permeability of the materials - often Triassic clays and marls - forming the closed depressions generates a local groundwater flow system that coincides with the surface watershed. The main surface water inputs comes from the watershed (runoff) and the main groundwater inputs comes from a local aquifer placed at the bottom of the closed depression. Water outputs are mainly due to the evaporation from the playa-lake and ET from the vegetation. This hypothesis is coherent with the geological origin and is supported by hydrological observation, numerical modelling and and surface-groundwater daily monitoring of time series in some of the studied playas. The southernmost playa lake studied is Medina playa-lake, hosted in the northern edge of a 1748 ha closed basin (Cádiz). The main structure that has generated the northern edge is an antiform with a core of Triassic and Miocene sediments and an upper part formed by alluvial conglomerates. This antiform acts as a barrier to the natural runoff, flowing to the north, remaining the cause for the genesis of the endorheic basin that leads to the establishment of the playa-lake. The Conde playa-lake (Córdoba province) is also placed in the northern edge of its 1109 ha closed basin. In this case, clay, gypsum-rich matrix tectonic mélange with a NE-SW orientation has been described in this sector. This melange define a non-continuous NE-SW uplift ridge, which acts as a natural barrier to the northwardly directed runoff originating the Conde playa-lake formation Finally, in Seville province, there is a large (251 km2) continental inner depression, formerly a Quaternary inland delta, that has lead to the

  13. 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.

  14. 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.

  15. 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.

  16. Assessing Nebraska playa wetland inundation status during 1985-2015 using Landsat data and Google Earth Engine.

    PubMed

    Tang, Zhenghong; Li, Yao; Gu, Yue; Jiang, Weiguo; Xue, Yuan; Hu, Qiao; LaGrange, Ted; Bishop, Andy; Drahota, Jeff; Li, Ruopu

    2016-12-01

    Playa wetlands in Nebraska provide globally important habitats for migratory waterfowl. Inundation condition is an important indicator of playa wetland functionality. However, there is a lack of long-term continuous monitoring records for playa wetlands. The objective of this study was to determine a suitable index for Landsat images to map the playa inundation status in March and April during 1985-2015. Four types of spectral indices-negative normalized vegetation index, Normalized Difference Water Index (NDWI), modified NDWI, and Tasseled Cap Wetness-Greenness Difference (TCWGD)-were evaluated to detect playa inundation conditions from Landsat images. The results indicate that the TCWGD is the most suitable index for distinguishing playa inundation status. By using Landsat images and Google Earth Engine, we mapped the spring inundation condition of Nebraska playas during 1985-2015. The results show that the total inundated areas were 176.79 km(2) in spring migratory season, representing 18.92% of the total area of playa wetlands. There were 9898 wetlands inundated at least once in either March or April during the past 30 years, representing 29.41% of a total of 33,659 historical wetlands. After comparing the historical hydric soil footprints and the inundated areas, the results indicate that the hydrological conditions of the majority of playas in Nebraska have changed. The inundated wetlands are candidates for protection and/or partial restoration, and the un-inundated wetlands need more attention for wetland restoration. Wetlands in areas enrolled in conservation easements had a significantly high level of playa inundation status than non-conserved wetlands during spring migratory seasons in the past decades.These conservation easements only count for 4.29% of the total footprint areas, but they have contributed 20.82% of the inundation areas in Nebraska during the past 30 years.

  17. 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.

  18. 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

  19. Effects of salinity and temperature on respiratory metabolism of Salicornia utahensis from a Great Basin playa

    Treesearch

    Lyneen C. Harris; M. Ajmal Khan; Jiping Zou; Bruce N. Smith; Lee D. Hansen

    2001-01-01

    Plants that live in the desert playas of the Great Basin must simultaneously tolerate very high concentrations of salt and high temperature. This study characterizes the respiratory metabolism of one species growing in this environment. An isothermal calorimetric method was used to measure the dark metabolic heat rate (q) and CO2 production rate (RCO2) of stem tissue...

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

    USDA-ARS?s Scientific Manuscript database

    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 ...

  1. Water balance in the playa-lakes of an arid environment, Monegros, NE Spain

    NASA Astrophysics Data System (ADS)

    Castañeda, Carmen; García-Vera, Miguel Ángel

    2008-02-01

    The playa-lakes of the Monegros desert in north-east Spain are saline wetlands in an arid environment, a rare phenomenon in Europe. These extremely valuable habitats are threatened by changes associated with agricultural expansion and incorporation of new irrigated areas. An understanding of the present hydrologic regime will enable changes to be identified, particularly those brought about by flooding and pollution caused by irrigation surplus. This study sets out to show the results of applying a daily water balance in three selected playa-lakes. The balance was in two parts and consisted of: (1) the average balance for all the endorheic basin using the BALAN_11 program, and (2) the water balance in some playa-lakes, applying discharge flows obtained from the previous balance. The resulting volumes of water were converted to water depths and contrasted with reference volumes taken from field and Landsat images. The model was calibrated by applying various hypotheses of function which enabled the results to be adjusted. The proposed balance is an acceptable reproduction of field water measurements during this period, and underlines the consistency of the conceptual model. The methodology used is appropriate for understanding the playa-lakes function and for monitoring them for conservation purposes.

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

    USDA-ARS?s Scientific Manuscript database

    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 ...

  3. Satellite Imagery Measures of the Astronomically Aligned Megalithis at Nabta Playa.

    NASA Astrophysics Data System (ADS)

    Brophy, T.; Rosen, P.

    The Nabta Playa megalithic complex consists of two types of features: first are the large stones, many of them shaped, placed on or in the sediments of an ancient seasonal lake bed that is now hyper-ariad, second are large sculpted bedrocks features underneath the sediments and associated with the surface megaliths (Wendorf et al. 1992). The astronomically aligned surface megalithic structures described in field reports (Wendorf and Malville, 2001) are identified in recent georectified 60cm panchromatic satellite imagery of Nabta Playa, Southern Egypt. The satellite images allow refinement, often significant of the reported locations of the megaliths (Malville et al 1998, and Wendorf and Malville 2001). The report that a primary megalithic alignment was constructed to point to the bright star Sirius, circa 4820BC, is reconsidered in light of the satellite data, new field, data, radiocarbon, lithostratigraphic and geochronological data, and the playa sedimentation history. Other possible archaeoastronomical interpretations are considered for that alignment, including the three star asterism (of Alnitak, Alniham and Mintaka) circa 6270BC that is also implicated in the small Nebta Playa "calendar circle". Signatures of other possible features apparent in the satellite imagery and a recent field study are also considered. Only a small number of the subsurface bedrock sculptures have been excavated. We recommend the use of ground penetrating imaging methods to illuminate the known but not yet excavated subsurface features. The problem of determining the astronomical intent of the builders of the megalithic structures is approached by considering the complex of features as a whole.

  4. Suitability of Eastern Gamagrass for in situ Precipitation Catchment Forage Production in Playas

    USDA-ARS?s Scientific Manuscript database

    Freshwater playas, shallow ephemeral lakes whose basins fill after periods of prolonged or intense rainfall preceding runoff events, occupy 3-5% of the land in the Llano Estacado and are considered marginal farmlands. The goals of this work were to determine if a native species, eastern gamagrass, c...

  5. 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

  6. Gypsum ground: a new occurrence of gypsum sediment in playas of central Australia

    NASA Astrophysics Data System (ADS)

    Xiang Yang Chen; Bowler, James M.; Magee, John W.

    1991-06-01

    There are many playas (dry salt lakes) in arid central Australia (regional rainfall about 250 mm/y and pan evaporation around 3000 mm/y). Highly soluble salts, such as halite, only appear as a thin (several centimetres thick), white, ephemeral efflorescent crust on the dry surface. Gypsum is the major evaporite precipitating both at present and preserved in sediment sequences. One type of gypsum deposit forms a distinctive surface feature, which is here termed "gypsum ground". It consists of a thick (up to 80 cm) gypsum zone which rises from the surrounding smooth white playa surface and is overlain by a heaved brown crust. The gypsum zone, with an average gypsum content above 60%, consists of pure gypsum sublayers and interlayered clastic bands of sandy clay. The gypsum crystals are highly corroded, especially in the direction parallel to the c-axis and on the upper sides where illuviated clay has accumulated in corrosion hollows. Overgrowth parallel to the a- and b-axes is very common, forming highly discoidal habits. These secondary changes (corrosion and overgrowth) are well-developed in the vadose zone and absent from crystals below the long-term watertable (depth around 40 cm). These crystal characteristics indicate a rainwater leaching process. At Lake Amadeus, one of the largest playas (800 km 2) of central Australia, such gypsum ground occupies 16% of the total area. The gypsum ground is interpreted as an alteration of a pre-existing gypsum deposit which probably extended across the whole playa before breaking down, leaving a playa marginal terrace and several terrace islands within the gypsum ground. This pre-existing gypsum deposit, preserved in the residual islands, consists of pure, pale, sand-sized lenticular crystals. It is believed to have been deposited during an episode of high regional watertable, causing active groundwater seepage and more frequent surface brine in the playa. A later fall in watertable, probably resulting from climatic change

  7. Anthropogenically accelerated sediment accumulation within playa wetlands as a result of land cover change on the High Plains of the central United States

    NASA Astrophysics Data System (ADS)

    Bowen, Mark W.; Johnson, William C.

    2017-10-01

    Playa wetlands are ubiquitous features of the central and southern Great Plains, and in Kansas alone, there are > 22,000 playas. Consequently, playas are critical wetland resources for the region, providing a range of ecosystem functions, such as groundwater recharge, surface water storage, and wetland habitat. Anthropogenically accelerated sediment accumulation is the primary impact reducing playa ecosystem functions. Objectives of this study were to estimate the amount of recent sediment accumulated within playas, determine how watershed and playa morphometry and land cover influenced sediment accumulation, and assess the role of grass buffers in reducing sediment accumulation. Land surveys and sediment thickness measurements were conducted throughout 64 Kansas playas with watershed cropland ranging from 0 to 100% and grass buffers ranging from non-existent to continuous to a width of ≥ 30 m. Results indicate watershed and playa morphometry have minimal influence on recent sediment accumulation within playas, and land-cover change is the primary driver. Playas without grass buffers within cropland watersheds on average accumulated 8.5 cm of recent sediment and lost 30% volume of storage capacity, while those with grass buffers in mixed cropland watersheds accumulated an average of 1.8 cm of recent sediment and lost 7% volume. Playas within grassland watersheds on average accumulated 2.3 cm of recent sediment and lost 13% volume. Grass buffers, while rarely utilized, could be highly effective at reducing the impacts of anthropogenically accelerated sediment accumulation and protecting playa ecosystem functions. Without grass buffers, anthropogenically accelerated sediment deliveries will continue to accumulate within playas, greatly reducing ecosystem functions, and, ultimately, many playas will disappear from the landscape.

  8. 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.

  9. Geochemical controls of groundwaters upwelling in saline environments: Case study the discharge playa of Sidi El Hani (Sahel, Tunisia)

    NASA Astrophysics Data System (ADS)

    Tagorti, Mohamed Ali; Essefi, Elhoucine; Touir, Jamel; Guellala, Rihab; Yaich, Chokri

    2013-10-01

    Within the discharge playa of Sidi El Hani, the surrounding aquifers converge due to uprising underground waters. The Principal Component Analysis proves that the fluid density is inversely influenced by the rainfall and has a reciprocal effect with evaporation. This parameter is governed by uprising groundwaters and the convergence of waters and inflow in the sabkha result in a geochemical exceptionality. The fluid density maintains high values during the year, the modeling of which shows a third sinusoidal distribution. This model remains stable along a span of time because the surrounding aquifer feeds the discharge playa by a continuous salty water flow. In general, waters in the majority of drills surrounding the discharge playa have the same facies which is mainly made up of water charged with Na+ and Cl-. A sample from the northeast of discharge playa shows a geochemical similarity with two wells located in its vicinity.

  10. Using Australian Acidic Playa Lakes as Analogs for Phyllosilicate and Sulfate Depositional Environments on Mars

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    Recent work on the origin of martian sulfates and their relationship to phyllosilicate deposits suggest that these deposits formed in different eras of Mars' history, under distinct environmental conditions. In southwestern Meridiani Planum phyllosilicates exist in close proximity to sulfate deposits. One possible explanation for this relationship is that it is an unconformable stratigraphic sequence, representing a significant change in aqueous geochemical conditions over time. Specifically, it may be interpreted to record a change in environment from neutral pH aqueous alteration in the Noachian to an acidic evaporitic system in the late Noachian to the Hesperian. On Earth, two different geochemical systems need not be evoked to explain such chemical variation. Acidic playa lakes in Western Australia have large pH differences separated by only a few tens of meters and demonstrate how highly variable chemistries can coexist over short distances in natural environments. Playa lakes on Earth tend to be dominated by lateral flow of water and salts leading to lateral chemical variation. Heterogeneity of playa mineralogy in Australia is due to the varied source rocks of brines and the mixing of dilute oxidizing brines and freshwater with the saturated evaporitic brines. This is evidenced by the ferricretes in the near-shore environment and more soluble phases in basin interiors. Playa lakes on Mars would be much larger than their terrestrial counterparts, leading to the prevalence of large-scale surface and crustal advection of water and salt rather than short-distance lateral flow, except at lake boundaries. Little or no influx of freshwater would preclude the formation of playa rim (e.g., crater rim) ferricretes and silcretes. Instead, we expect to see mainly vertical facies changes, and any diachronous lateral facies changes are expected to occur on very large spatial scales. Comparison of high spatial resolution, hyperspectral airborne data for Australian playa

  11. Surface water hydrology and geomorphic characterization of a playa lake system: Implications for monitoring the effects of climate change

    NASA Astrophysics Data System (ADS)

    Adams, Kenneth D.; Sada, Donald W.

    2014-03-01

    Playa lakes are sensitive recorders of subtle climatic perturbations because these ephemeral water bodies respond to the flux of diffuse and channelized flow from their watersheds as well as from direct precipitation. The Black Rock Playa in northwestern Nevada is one of the largest playas in North America and is noted for its extreme flatness, varying less than one meter across a surface area of 310 km2. Geo-referenced Landsat imagery was used to map surface-area fluctuations of ephemeral lakes on the playa from 1972 to 2013 to provide baseline data on surface water hydrology of this system to compare to future hydrologic conditions caused by climate change. The area measurements were transformed into depth and volumetric estimates using results of detailed topographic global positioning system (GPS) surveys and correlated with available surface hydrological and meteorological monitoring data. Playa lakes reach their maximum size (<350 km2) in spring, fed by melting snows from high mountains on the periphery of the drainage basin, and usually desiccate by early- to mid-summer. The combination of a shallow groundwater table, sediment deposition, and hydro-aeolian planation probably are largely responsible for the flatness of the playa. When lakes do not form for a period of several years, the clay- and silt-rich playa surface transforms from one that is hard and durable into one that is soft and puffy, probably from upward capillary movement of water and resultant evaporation. Subsequent flooding restores the hard and durable surface. The near-global availability of Landsat imagery for the last 41 years should allow the documentation of baseline surface hydrologic characteristics for a large number of widely-distributed playa lake systems that can be used to assess the hydrologic effects of future climate changes.

  12. Sliding stones of Racetrack Playa, Death Valley, USA: The roles of rock thermal conductivity and fluctuating water levels

    NASA Astrophysics Data System (ADS)

    Kletetschka, Gunther; Hooke, Roger LeB.; Ryan, Andrew; Fercana, George; McKinney, Emerald; Schwebler, Kristopher P.

    2013-08-01

    On occasion, Racetrack playa in Death Valley National Park becomes flooded and temperatures then drop appreciably below freezing. The thermal conductivity of rock is greater than that of water, so heat is conducted from a partially-submerged rock faster than from water. Consequently, a collar of thicker ice forms at the water surface, a layer of ice forms on more deeply-submerged parts of the rock, and playa sediment beneath the rock may even become frozen to it. While this occurs, only a surface layer of ice forms on water away from the rock. Once the ice becomes thick enough, perhaps only 5-10 mm, either the buoyancy of the ice or additions of water to the playa by rain, snow-melt, or groundwater seepage then reduce the normal force between the rock and the playa to the point where wind shear can move the ice sheet with its entrained rocks, making trails (Stanley, 1955; Reid et al., 1995). After the ice melts, rocks are left at the ends of the trails, sometimes atop a pedestal of silt. A renewed increase in water level on the playa before the ice melts may lift a rock completely free of the playa surface and whisk it away, leaving a rockless trail. During a movement event, changes in rock orientation or water depth may result in changes in width along the track. Rock speeds are likely tens to hundreds of millimeters per second.

  13. Relief Inversion in the Avrona Playa as Evidence of Large-Magnitude Historical Earthquakes, Southern Arava Valley, Dead Sea Rift

    NASA Astrophysics Data System (ADS)

    Amit, Rivka; Zilberman, Ezra; Porat, Naomi; Enzel, Yehouda

    1999-07-01

    The Arava Valley section of the Dead Sea Transform (DST) in southern Israel is characterized by the absence of seismic activity in recent times. However, paleoseismic analysis of sediments in the Avrona Playa, a pull-apart basin along the DST, reveals that at least six M > 6 tectonic events have affected the Avrona playa in the last 14,000 yr. The recurrence interval of the events is approximately 2000 yr. Trenched normal faults and push-up ridges in the playa show that the upper 2 m of the deformed sedimentary sequence consists of playa deposits with uniform soil development. The deformed sediments and the soil are typical of basins with an endoreic fluvial system. Based on the limiting age of the sequence and the extent of soil development, faulting in the playa, followed by compression and uplift, occurred in the last 1000 yr. This most recent tectonic event displaced the surface by at least 1 m, consistent with a M > 6.5 earthquake. This earthquake changed the morphology of the Avrona Playa from a closed system with internal drainage to an open basin, resulting in relief inversion. The seismic quiescence in the Arava may indicate a seismic gap in this segment of the DST.

  14. Depositional and diagenetic processes of Qa Khanna playa, North Jordan basaltic plateau, Jordan

    NASA Astrophysics Data System (ADS)

    Howari, F. M.; Banat, K. M.; Abu-Salha, Y. A.

    2010-09-01

    The present study explored mineral occurrences and sediment characteristics of playas from northern Jordan and explained depositional and diagenetic processes as reflected from bulk chemistry and sedimentary structures. Mudcracks of different sizes and shape patterns, laminations, intersediment vesicles, and bioturbation pipes are the main sedimentary structures. Plagioclase, olivine, orthopyroxene, nepheline and other opaque minerals are all of detrital origin, and are derived from the basaltic bedrocks surrounding the studied playa. Evaporites are very rare; they are represented only by trace amounts of gypsum. The identified clay minerals in the clay fraction of the studied sediments, arranged according to their decreasing abundances are palygorskite, illite, kaolinite, smectite and chlorite. The elemental abundances were tied to clay, CaCO 3 and nearby igneous rocks. The type of clay minerals, the high pH values of the studied sediments, and the considerable incorporation of Mg and K in palygorskite and illite respectively, may strongly reflect a high evaporative and alkaline environment under arid to semi-arid conditions in an ephemeral lake of the Qa Khanna. Concentrations and distributions of both major and trace elements are essentially controlled by the clay mineralogy and the calcium carbonate content; Ca is mainly incorporated in the CaCO 3, which is either generated authigenically or by aeolian deposition. Fe and K are incorporated and fixed by illite under an evaporative and alkaline environment. Mg is incorporated in palygorskite while Mn is adsorbed on various clay minerals. Sr substitutes for Ca in the aeolian CaCO 3 and its presence in the studied sediments is independent of the prevailing conditions during the playa evolution. Rb substitutes for K in illite under the prevailing chemical conditions in the studied playa.

  15. Specular scattering on a terrestrial playa and implications for planetary surface studies

    NASA Technical Reports Server (NTRS)

    Shepard, Michael K.; Arvidson, Raymond E.; Guinness, Edward A.

    1993-01-01

    Multiangle Advanced Solid State Array Spectroradiometer (ASAS) and Portable Apparatus for Rapid Acquisition of Bidirectional Observations of Land and Atmosphere (PARABOLA) visible and near infrared reflectance data covering the Lunar Lake playa, Nevada, were modeled using specular and volume scattering theory. The volume component used to model the data was based on the Hapke (1986) model and the specular scattering component was based on Fresnel reflection from surface facets with a distribution of tilts. Specular scattering was needed to explain the several-fold increase in reflectance observed at high phase angles in the solar principal plane. Results imply single scattering albedos of approximately 0.93 to 0.95, a real index of refraction value of approximately 1.52 (at a wavelength of 0.66 micron), a small imaginary index of refraction and an exponential facet tilt probability function for the playa. Electron micrographs showed th playa surface to consist of ensembles of smooth, micrometer-scale ellipsoidal particles on gently undulating topography at the millimeter to centimeter scale. The exponential probability function is consistent with this observation. Mars and the icy satellites are discussed as possible places to look for a significant specular scattering component.

  16. Elemental geochemistry of wind-erodible playa sediments, Owens Lake, California

    NASA Astrophysics Data System (ADS)

    Gill, Thomas E.; Gillette, Dale A.; Niemeyer, Tezz; Winn, Russell T.

    2002-04-01

    Wind erosion of the dried bed (playa) of Owens Lake, California is an extremely intense source of mineral aerosol, transporting dust hundreds of kilometers downwind to critical ecological areas and several cities. A dust-producing site on the playa was studied over a four-year period to document the processes associated with aerosol emission. The playa takes on a variety of sedimentary forms and phases with surface crusts of differing susceptibilities to wind erosion. The sediments are classed into three general categories based on appearance: soft (saline), loose with drifting sand (salt-silt-clay), and hard and clean (silt-clay). Sediment samples were collected over a two-year period as the study site cycled through all three crust types, and the samples were crushed and analyzed by PIXE. The results indicate that visual appearance and sedimentary structure does not correlate with elemental composition. All sediment types contain significant concentrations of various elements including sodium, calcium and silicon. Potentially toxic trace elements are also found in the sediments. All sediment types contain lead and/or arsenic in tens of parts per million, as well as various other heavy metals. Pb and As levels do not clearly correlate with salt content or sediment type. Arsenic levels may be slightly higher in the crusts with loose material present and potentially lower in the clean hard crusts, while Pb was least frequently detected in the samples with loose material. Future research will add mineralogical and stable isotope analyses to correlate with the PIXE data.

  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. 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.

  19. Specular scattering on a terrestrial playa and implications for planetary surface studies

    NASA Astrophysics Data System (ADS)

    Shepard, Michael K.; Arvidson, Raymond E.; Guinness, Edward A.

    1993-10-01

    Multiangle Advanced Solid State Array Spectroradiometer (ASAS) and Portable Apparatus for Rapid Acquisition of Bidirectional Observations of Land and Atmosphere (PARABOLA) visible and near infrared reflectance data covering the Lunar Lake playa, Nevada, were modeled using specular and volume scattering theory. The volume component used to model the data was based on the Hapke (1986) model and the specular scattering component was based on Fresnel reflection from surface facets with a distribution of tilts. Specular scattering was needed to explain the several-fold increase in reflectance observed at high phase angles in the solar principal plane. Results imply single scattering albedos of approximately 0.93 to 0.95, a real index of refraction value of approximately 1.52 (at a wavelength of 0.66 micron), a small imaginary index of refraction and an exponential facet tilt probability function for the playa. Electron micrographs showed th playa surface to consist of ensembles of smooth, micrometer-scale ellipsoidal particles on gently undulating topography at the millimeter to centimeter scale. The exponential probability function is consistent with this observation. Mars and the icy satellites are discussed as possible places to look for a significant specular scattering component.

  20. Dust emission at Franklin Lake Playa, Mojave Desert (USA): Response to meteorological and hydrologic changes 2005-2008

    USGS Publications Warehouse

    Reynolds, Richard L.; Bogle, Rian C.; Vogel, John; Goldstein, Harland; Yount, James

    2009-01-01

    Playa type, size, and setting; playa hydrology; and surface-sediment characteristics are important controls on the type and amount of atmospheric dust emitted from playas. Soft, evaporite-rich sediment develops on the surfaces of some Mojave Desert (USA) playas (wet playas), where the water table is shallow (< 4 m). These areas are sources of atmospheric dust because of continuous or episodic replenishment of wind-erodible salts and disruption of the ground surface during salt formation by evaporation of ground water. Dust emission at Franklin Lake playa was monitored between March 2005 and April 2008. The dust record, based on day-time remote digital camera images captured during high wind, and compared with a nearby precipitation record, shows that aridity suppresses dust emission. High frequency of dust generation appears to be associated with relatively wet periods, identified as either heavy precipitation events or sustained regional precipitation over a few months. Several factors may act separately or in combination to account for this relation. Dust emission may respond rapidly to heavy precipitation when the dissolution of hard, wind-resistant evaporite mineral crusts is followed by the development of soft surfaces with thin, newly formed crusts that are vulnerable to wind erosion and (or) the production of loose aggregates of evaporite minerals that are quickly removed by even moderate winds. Dust loading may also increase when relatively high regional precipitation leads to decreasing depth to the water table, thereby increasing rates of vapor discharge, development of evaporite minerals, and temporary softening of playa surfaces. The seasonality of wind strength was not a major factor in dust-storm frequency at the playa. The lack of major dust emissions related to flood-derived sediment at Franklin Lake playa contrasts with some dry-lake systems elsewhere that may produce large amounts of dust from flood sediments. Flood sediments do not commonly

  1. 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

  2. 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

  3. 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

  4. Tectonic Controls on the development of Continental Playa-Lakes of the Guadalquivir River Basin (Betics, Spain)

    NASA Astrophysics Data System (ADS)

    Rodriguez-Rodriguez, M.; Moral, F.; Balanyá, J.; Diaz, M.; Exposito, I.

    2009-12-01

    Tectonic Controls On The Development Of Continental Playa-Lakes Of The Guadalquivir River Basin (Betics, Spain). Low permeable materials belonging to both the Olistostromic Unit (OU) and the Subbetic Zone (SZ) of the Betic orogen (southern Spain) define an ENE-WSW band located in the external part of the foreland fold-and-thrust belt. A notable hydrological feature observed in these materials is the presence of hundreds of ephemeral playa-lakes of different sizes, ranging from less than 1 ha to more than 1500 ha. Previous hydrogeological studies in the main playa-lakes of the OU/SZ have shown that the hydrological function unit in most of these ecosystems is the watershed, and that the water inputs filling the depressions come mainly from the surface and groundwater flows generated over such watershed. Nevertheless, the origin and formation of such endorheic depressions has been traditionally attributed to the karstification of evaporite rocks, mainly salt and gypsum, at a certain depth. There are no hydrogeological evidences, such as the existence of a karstic draining network (i.e. sinkholes or springs) that correlate with such hypothesis. Geological and morphological surveys made in the majority of these basins suggest that, although karstic phenomena have been observed in several wetlands, tectonic processes have a great importance in the formation of the depressions hosting playa-lakes and, thus, karstification may operate as a secondary process in the generation of the majority of the closed depressions. The main geomorphological features that have been recognized are: 1)The elongate shape and orientation of individual and/or groups of playa-lakes and associated depressions that are closely coincident with the prevailing structural directions in the region (NE-SW to ENE-WSW) and, 2)Field evidences of halokinetic movements that extrude materials and forms depressions, occasionally hosting playa-lakes at the borders. Because karst-based models do not fit a

  5. 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.

  6. Monitoring playa lake inundation in the western United States: Modern analogues to late-Holocene lake level change

    NASA Astrophysics Data System (ADS)

    Scuderi, Louis A.; Laudadio, Christine K.; Fawcett, Peter J.

    2010-01-01

    Closed basin playas are among the most sensitive hydrologic systems globally and are excellent indicators of current and past climatic variability. This variability can significantly impact hydrologic regimes and biotic communities, and is often expressed in lake-bed deposits and shoreline features. We analyzed two playa basins in western North America that lie to either side of the current divide between monsoon and westerly precipitation regimes. Using a 23-year sequence of Landsat images at a 16-day time step, we determined the playa inundation response to varying precipitation inputs. Our results show that a strongly contrasting lake-inundation response occurs in lake basins separated by only 200 km. The Animas/Lordsburg Basin shows a marked lake-area increase in response to winter precipitation events, while the more southerly Palomas Basin shows a stronger response to monsoonal and El Niño-type events. This sensitivity to different input sources over short distances may explain some of the apparent asynchronous behavior of playa response found in lake records. Comprehensive regional-scale inundation records could be used to understand the dynamics of playa inundation events and how these events are linked to atmospheric circulation, and possibly to understand the observed asynchronous behavior of lake basins during the late Pleistocene and Holocene.

  7. 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.

  8. 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.

  9. 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.

  10. Scattering behavior of Lunar Lake playa determined from parabola bidirectional reflectance data

    NASA Technical Reports Server (NTRS)

    Shepard, Michael K.; Arvidson, Raymond E.; Guinness, Edward A.; Deering, Donald W.

    1991-01-01

    Bidirectional reflectance data obtained with the Portable Apparatus for Rapid Acquisition of Bidirectional Observations of Land and Atmosphere instrument at Lunar Lake, Nevada, were analyzed to determine the scattering properties of playas. The data are approximated by a Lambertian function, except at high phase angles in the solar principal plane, where Fresnel reflectance appears to dominate. The data also depart slightly (15 percent) from a Lambertian function at high emission angles in all azimuthal planes. No published photometric model accounts for the observed data. It is hypothesized that the observed scattering behavior is the superposition of volume and surface (Fresnel) scattering mechanisms.

  11. Declining rock movement at Racetrack Playa, Death Valley National Park: An indicator of climate change?

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.; Jackson, Brian K.

    2014-04-01

    We have inspected Racetrack Playa at Death Valley over the last 7 years and have not observed major episodes of rock movement and trail generation. We compare this null observation with the literature record of the rock movement using a Monte Carlo method and find 4-to-1 odds that the rock movement probability has systematically declined. This statistically significant drop in movement rate may indicate a change in the probability of the required conditions for movement: we note decline in the occurrence of strong winds and in ice-forming cold in nearby weather records. Rock movement and trail formation may serve as an indicator of climate change.

  12. 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

  13. Scattering behavior of Lunar Lake playa determined from parabola bidirectional reflectance data

    NASA Technical Reports Server (NTRS)

    Shepard, Michael K.; Arvidson, Raymond E.; Guinness, Edward A.; Deering, Donald W.

    1991-01-01

    Bidirectional reflectance data obtained with the Portable Apparatus for Rapid Acquisition of Bidirectional Observations of Land and Atmosphere instrument at Lunar Lake, Nevada, were analyzed to determine the scattering properties of playas. The data are approximated by a Lambertian function, except at high phase angles in the solar principal plane, where Fresnel reflectance appears to dominate. The data also depart slightly (15 percent) from a Lambertian function at high emission angles in all azimuthal planes. No published photometric model accounts for the observed data. It is hypothesized that the observed scattering behavior is the superposition of volume and surface (Fresnel) scattering mechanisms.

  14. Dust Emissions from Undisturbed and Disturbed, Crusted Playa Surfaces: Cattle Trampling Effect

    NASA Astrophysics Data System (ADS)

    Zobeck, T. M.; Baddock, M. C.; van Pelt, R.; Fredrickson, E. L.

    2009-12-01

    Dry playa lake beds can be a significant source of fine dust emissions during high wind events in arid and semiarid landscapes. The physical and chemical properties of the playa surface control the amount and properties of the dust emitted. In this study, we use a field wind tunnel to quantify the dust emissions from a bare, fine-textured playa surface located in the Chihuahua Desert at the Jornada Experimental Range, near Las Cruces, New Mexico, USA. We tested natural, undisturbed crusted surfaces and surfaces that had been subjected to two levels of domestic animal disturbance. The animal disturbance was provided by trampling produced from one and ten passes along the length of the wind tunnel by a 630 kg Angus-Hereford cross cow. The trampling broke the durable crust and created loose erodible material. Each treatment (natural crust, one pass, and ten passes) was replicated three times. A push-type wind tunnel with a 6 m long, 0.5 m wide, and 1 m high test section was used to generate dust emissions under controlled conditions. Clean medium sand was dropped onto the playa surface to act as an abrader material. The tunnel wind speed was equivalent to 15 m/s at a height of 2 m over a smooth soil surface. The tunnel was initially run for ten minutes, with no abrader added. A second 30 minute run was subsequently sampled as abrader was added to the wind stream. Dust and saltating material were collected using an isokinetic slot sampler at the end of the tunnel. Total airborne dust was collected on two 25 cm x 20 cm glass fiber filters (GFF) and measured using a GRIMM particle monitor every 6 sec throughout each test run. Disturbance by trampling generated increased saltating material and airborne dust. The amount of saltating material measured during the initial (no abrader added) run was approximately 70% greater and 5.8 times the amount of saltating material measured on the one pass and ten pass plots, respectively, compared with that observed on the undisturbed

  15. Temperature and Emissivity Measurements with the Multispectral Thermal Imager Satellite at Ivanpah Playa

    SciTech Connect

    Villa-Aleman, E.

    2003-01-06

    The Multispectral Thermal Imager (MTI) is a research and development satellite sponsored by the Department of Energy (DOE) for accurate water surface temperature retrieval. MTI uses five thermal spectral bands to retrieve ground temperatures. The application of MTI for land-based temperature and emissivity retrieval has been limited. Savannah River Technology Center conducted several ground truth campaigns at Ivanpah Playa to measure reflectance, temperature and emissivity. The results of MTI temperature and emissivity retrievals and material identification will be discussed in context with the ground truth data.

  16. 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.

  17. [Reef fishes community structure of Playa Mero, Parque Nacional Morrocoy, Venezuela].

    PubMed

    Rodríguez, J; Villamizar, E

    2000-12-01

    The coral reef fish community was studied in Playa Mero, Morrocoy National Park, after the mass mortality of January, 1996 with a systematic sampling design. Transects and quadrates were used for corals, and a visual census for fishes. The coral community is highly disturbed with extensive areas of dead coral covered by algae, and low coverage and richness of coral species, gorgonians, sponges and briozooans. These factors have generated a relatively homogeneous environment with respect to the fish community, which was dominated by Scaridae and Pomacentridae that represented 75% of fish. Dominant fishes were mainly herbivorous (75.4% of all fish) apparently because of the disturbance that caused the settling of algae.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Trends in playa inundation and water storage in the Ogallala Aquifer and on the Texas High Plains

    USDA-ARS?s Scientific Manuscript database

    The Ogallala Aquifer is an important source of irrigation water on the Texas High Plains; however, significant decreases in saturated thickness threaten its future use for irrigation. A better understanding of the roles of playas, ephemeral surface ponds, in aquifer recharge is needed to establish l...

  6. Hydrogeological behaviour of the Fuente-de-Piedra playa lake and tectonic origin of its basin (Malaga, southern Spain)

    NASA Astrophysics Data System (ADS)

    Rodriguez-Rodriguez, Miguel; Martos-Rosillo, Sergio; Pedrera, Antonio

    2016-12-01

    Changes in the quantity of groundwater input due to water extraction for irrigation and urban supply has modified the water balance in the Fuente de Piedra playa lake. We have analysed the hydrogeology of the playa-lake system and developed a water-level model by means of a simple long-term water balance and piezometric analysis. In addition, a tectonic model is proposed to explain the endorheic basin development that led to the formation of the playa. Upright folds developed since the late Miocene and density-driven subsidence favoured the setting-up of and endorheic system located between the Atlantic and the Mediterranean basins in the Quaternary. The underlying low permeability rocks beneath the playa form a very stable aquitard with highly saline groundwater that prevents groundwater recharge of the lake into the aquitard. The hydrological modelling allowed us to simulate the evolution of the wáter level under a scenario of unaltered conditions during a 13-year period, showing that the percentage of days with dry conditions varies from 24.8% of the time under altered conditions to 14.9% as far as an unaltered scenario is concerned.

  7. The role of water in the development of surface roughness and mineralogical variability on playa surface sediments: Implications for aeolian erodibility and dust emission

    NASA Astrophysics Data System (ADS)

    Tollerud, Heather J.

    Playas are significant sources for atmospheric mineral dust, but the evolution of their surface erodibility through time is not well established, leading to difficulties in modeling dust emission. Investigation of the spatial and temporal variability of surfaces within dust source regions has the potential to elucidate the processes that control erodibility and to improve model predictions of dust emission. In this dissertation the variability in time and space of surface mineralogical composition, particle size distribution, and surface roughness is measured in a playa (the Black Rock Desert, NV, USA). Water is found to be critical to the development of playa surfaces. Analysis of samples from the Black Rock playa demonstrates that the playa is mainly composed of quartz (˜30 wt%), clay (˜45 wt%), plagioclase (˜10 wt%), calcite (2-15 wt%), and halite (0-40 wt%). Composition varies between the center of the playa (more frequently inundated) and edge, with smaller particles, more clay, less plagioclase, and less calcite in the central areas. The surface roughness of the Black Rock playa is observed through time (2004-2010) using synthetic aperture radar (SAR) remote sensing data. Surface roughness is relatively constant during the dry summer months, but changes significantly from year to year, suggesting that water and inundation have more control on playa surfaces than anthropogenic activity or saltation abrasion. Roughness is low in years with heavy precipitation, but late drying areas of the playa are rough. Small scale lab experiments on a playa analog surface demonstrate that cycles of wetting/drying increase roughness, particularly for surfaces with added CaCO 3; a surface with added CaCO3 produced aggregates of a size appropriate for saltation (<100 microm) through wetting/drying cycles, while a surface with added NaCl remained relatively smooth. These observations suggest a conceptual framework for the development of surfaces in a playa: inundation smooths

  8. 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??.

  9. Dust emission thresholds from sodic playas with varying geochemistry and environmental conditions

    NASA Astrophysics Data System (ADS)

    Nield, J. M.; McKenna Neuman, C.; O'Brien, P.

    2014-12-01

    Sodic playa surfaces can be major sources of dust emission but their erodibility depends on the surface salt crust characteristics. Here we determine dust emission thresholds in a wind tunnel for 22 different crusts with varying concentrations of sodium sulphate and sodium chloride. Crusts mimic those on Sua Pan, in the Makgadikgadi Basin, Botswana, which is one of the biggest dust hot spots in the Southern Hemisphere. Crusts were grown by encouraging capillary processes and subjected to several weeks of diurnal temperature variation to enable the development of hydrated and dehydrated salt crystals, along with low density, 'fluffy' sediment beneath the primary (and in some cases, secondary) crust. Spray on crusts and liquefied crusts were also developed for response comparison. Using laser scanning we tracked surface change and crystal growth, which we link to crust type and evaporation rates. We found that under pre-dawn and early morning Sua Pan conditions, crusts were typically non-emissive, but during mid-day temperature and humidity conditions typical of Sua Pan in August and September (dry and peak dust emission season), several crusts became friable and highly emissive above wind velocities of 7 m/s, which agrees with in-situ field observations. Thenardite capillary crusts were the most emissive, in contrast to supply limited, halite liquefied crusts which were relatively stable. Disturbances, or small crust fractures, common on polygonal surface patterns decreased the dust emission threshold values and enabled emission from more stable crusts. Our study confirms the potential of playa surfaces to emit dust without the presence of saltation, and highlights the sensitivity of emission thresholds to crust geochemistry, evaporation rates and temperature and humidity conditions.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Late Quaternary sedimentology and geochronology of small playas on the Southern High Plains, Texas and New Mexico, U.S.A.

    NASA Astrophysics Data System (ADS)

    Holliday, Vance T.; Mayer, James H.; Fredlund, Glen G.

    2008-07-01

    Playas are small, circular basins forming a ubiquitous component of the southern High Plains landscape. They are filled with carbonaceous mud deposited since the terminal Pleistocene. The stratigraphy and geochronology of 30 playas was investigated to better understand the paleoenvironmental record of basin filling. At the base of the fill in some playas is a well sorted eolian sand dated between ~ 13,000 and ~ 11,000 14C yr BP. The beginning of mud deposition, representing aggradation of eolian dust on a moist, vegetated playa floor was largely between ~ 12,000 and ~ 10,500 14C yr BP. Playa filling slowed ~ 9000 to ~ 4000 14C yr BP, probably due to dry conditions, increased ~ 4000 to ~ 2000 14C yr BP, then slowed again. Eolian sand and loam, likely representing regional aridity, accumulated in some basins episodically just prior to ~ 10,700 14C yr BP, between ~ 8600 and ~ 4700 14C yr BP, and at ~ 1300 14C yr BP. Stable C isotopes from one basin indicate that the playa was inundated only seasonally throughout the record beginning ~ 11,500 14C yr BP. The phytolith record in that basin indicates an abrupt shift toward cooling ~ 11,400 to ~ 11,200 14C yr BP and then increasing importance of xeric-adapted C 4 grasses through the Holocene.

  15. Microbial Ecology of Sediment-Groundwater Interface in the Lake Lucero Playa at the White Sands National Monument, New Mexico

    NASA Astrophysics Data System (ADS)

    Ramirez, S.; Glamoclija, M.; Widanagamage, I. H.; Zeidan, M.; Potochniak, S.

    2016-12-01

    The microbial ecology of playa lake sediments at the White Sands National Monument in New Mexico is conditioned by the physical and geochemical parameters of the surrounding environment, which due to its aridity and hypersalinity is considered an extreme habitat. The goal of this study is to couple microbial diversity analysis to environmental variations in geochemistry and mineralogy to learn more about the interactions of the microorganisms with their environment and to see how similar or different the communities that live at the surface and subsurface are from those in the groundwater and whether there is any overlap between the two. The 1m depth profile collected in the middle of the modern playa consists of predominantly gypsum minerals mixed with some quartz and minor mirabilite, halite, quartz, epsomite, celestine, and clays. The cation analysis has shown variation among different depth samples; however, the pending anion analysis coupled with detailed mineralogical data will provide a better insight into inorganically driven changes within this environment. SEM/EDS analysis showed no obvious microbial morphologies or biofilm in any of the samples. However, some unusual carbon-rich structures have been seen that may possibly be of biological origin. DNA isolation has been completed and the extracts have been sent out for Illumina MiSeq 515 sequencing. OUT-based analysis will be performed using Mothur and the data will be discussed and presented at the conference. Through this study, we are hoping to reveal what survival strategies microbes utilize to live and thrive in this extreme environment. Furthermore, much of the previous microbially-themed research on playa lakes has focused on studying the microbes within the actual water columns of the playas rather than the sediments or the groundwater, so this research will expand upon a poorly-understood field of study.

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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.

  1. Eolian deposition cycles since AD 500 in Playa San Bartolo lunette dune, Sonora, Mexico: Paleoclimatic implications

    NASA Astrophysics Data System (ADS)

    Ortega, Beatriz; Schaaf, Peter; Murray, Andrew; Caballero, Margarita; Lozano, Socorro; Ramirez, Angel

    2013-12-01

    Records of past climatic changes in desert environments are scarce due to the poor preservation of biological proxies. To overcome this lack we consider the paleoenvironmental significance and age of a lunette dune at the eastern rim of Playa San Bartolo (PSB) in the Sonoran Desert (Mexico). Thermoluminescence and optical stimulated luminescence (TL and OSL) provide the chronology of lunette dune development. Mineralogical, geochemical (major, trace and REE element concentrations) and rock magnetic analyses allow for the assessment of sediment provenance and changes in the composition of the PSB dune over time. The upper 6 m of dune accumulation occurred over the past 1.5 ka, largely during AD 500-1200, a period that correlates with the Medieval climatic anomaly (AD 300-1300). Variability in composition of dune sediments is attributed to changes in sediment sources. Sand sized deposits are mainly eroded from granitoids from nearby outcrops. Sandy silt deposits, rich in evaporative minerals, resulted after the flooding of PSB, later deflation and accumulation of both detritic and authigenic components in the dune. These findings suggest that main dune accretion occurred during regionally extended drought conditions, disrupted by sporadic heavy rainfall.

  2. Eolian sand deposition during th Medieval Climatic Anomaly in Playa San Bartolo, Sonora, Mexico

    NASA Astrophysics Data System (ADS)

    Ortega, B.; Schaaf, P. E.; Murray, A.; Caballero, M.; Lozano Garcia, S.; Ramirez, A.

    2012-12-01

    Records of past climatic changes in desert environments are scarce due to the poor preservation of biological proxies. To overcome this lack we consider the paleoenvironmental significance and age of a lunette dune in the eastern rim of the Playa San Bartolo (PSB) in Sonoran Desert (Mexico). Rock magnetism, mineralogical, and geochemical analysis (major, trace and REE) allow assessment of sediment provenance and changes in the composition of the PSB dune over time. Thermoluminiscence and optical stimulated luminescence (TL and OSL) provide the chronology of lunette dune development. Dune sediments are composed by intercalated layers of sand beds and sandy silt strata. Variability in composition of dune sediments is attributed to changes in sediment sources. Mineralogical, geochemical and magnetic data show clear differences between the sand and the sandy silt of the PSB dune deposits, which suggest different sediment sources. Sand sized deposits, characterized by coarse magnetite grains, are mainly eroded from granitoids from nearby outcrops. Sandy silt deposits, rich in fine grained magnetite and evaporative minerals, resulted after the erosion of volcanic rocks and their soils from sierras at the NE of PSB during heavy rainfall episodes, the flooding of PSB and later deflation and accumulation in the dune of both detritic and authigenic components. The upper 6 m of dune accumulation occurred largely during AD 500 to 1200, a period that correlates with the Medieval climatic anomaly (AD 300 to 1300). These findings suggest that main dune accretion occurred during regionally extended drought conditions, disrupted by sporadic heavy rainfall.

  3. 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

  4. Inflow to a crack in playa deposits of Yucca Lake, Nevada Test Site, Nye County, Nevada

    SciTech Connect

    Doty, G.C.; Rush, F.E.

    1985-01-01

    A crack about 1 mile long opened in 1969 in the dry bed of Yucca Lake, a playa on the Nevada Test Site. Accumulation of water from precipitation on the lakebed drained rapidly into the crack and led to concern whether the water entering the crack was directly recharging the very transmissive Paleozoic carbonate comprising the aquifer for the regional flow system. If so, runoff from nearby areas for past surface testing of nuclear devices possibly could contribute residual radioactive contaminants directly to the regional flow system by draining into this and similar cracks. An effort was made to determine the quality of water entering the crack by installing 10 Parshall flumes in a berm surrounding the crack and by monitoring inflow for about 3 years. Flow records from the flumes indicate that an estimated 5 million cubic feet of water flowed into the crack during the period of measurements. Results of one sample of water analyzed for chemical constituents and of several samples analyzed for radioactivity indicate that the water that entered the crack constituted no human-health hazard. In the event another crack opens in the lakebed, and if additional study is undertaken, an improved method of monitoring inflows would result in better records and improved understanding of these cracks.

  5. Sand-flat/playa mud-flat-lacustrine cycles in Fundy rift basin (Triassic-Jurassic), Nova Scotia: implications for climatic and tectonic controls

    SciTech Connect

    Mertz, K.A. Jr.; Hubert, J.F.

    1989-03-01

    Blomidon Formation red beds comprise over 200 m-scale cycles of (1) sand-flat sandstone (distal alluvial-fan deposits) and (2) playa sandy mudstone and/or lacustrine claystones. Rift basin subsidence and local sagging along the Glooscap fault system generated sand-flat/playa mud-flat cycles by shifting loci of active fan sedimentation toward and away from the playa surface as fan lobes migrated toward topographic lows. Episodes of intense aridity are recorded in the sand-flat and playa mud-flat deposits where amalgamated sheetflood packages are characterized by pervasive evaporite mineralization (principally gypsum) controlled by subsurface evolution of a Ca-SO/sub 4/-Na-Cl brine. Aridity is further evidenced by significant disruption of sedimentary fabrics beneath evaporite crusts, deep mud cracks, eolian sandstone layers and patches, and precipitation of authigenic calcium and magnesium-rich illite/smectite and analcime. Carbon isotopic data from early formed, low-magnesium calcite cements (pre-gypsum) reflect slightly to moderately elevated subsurface salinities that accompanied initial brine evolution. During relatively wetter periods, lacustrine platy claystones accumulated in shallow, oxidizing lakes that lapped onto the sand flats. Claystone units lack evaporite minerals and textures, and many units are partially burrowed. Carbon isotopic data from calcite cements are consistently lighter than sand-flat/playa mud-flat calcites and were in equilibrium with relatively fresh subsurface pore waters.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. [Biology and fishery of the lobster Panulirus gracilis in Playa Lagarto, Guanacaste, Costa Rica].

    PubMed

    Madrigal, Helven Naranjo

    2011-06-01

    Panulirus gracilis is a high valuable lobster species with considerable captures along the tropical Pacific coast. In this study, I present some biological and fishery parameters described after a sample of 843 lobsters, landed in Playa Lagarto from November 2007 to October 2008. From landing records, a total of 74.9% of lobsters were below the minimum legal catch size (80 mm CL). Carapace lengths were in the range of 42.8 and 143.6 mm for males and 115 and 35.8 mm for females. The size structure showed a wide overlapping of population segments, and a trend to increase with depth, where lung diving and "hooka" diving operations take place. Sex ratio was 1.36 M:H. The relationship between weight and LC revealed that females are heavier than males of the same size, and this difference was significant (p < 0.05). The von Bertalanffy growth parameters for males and females respectively (K = 0.45-0.38, LC(infinity) = 166.9-121.7) showed accelerated growth compared to other species. Males observed a higher growth rate than females. Furthermore, natural mortality (M), total mortality (Z) and fishing mortality (F) was higher in males (0.49-2.34-1.92) than in females (0.47-1.82-1.42). Recruitment was continuous for both sexes during the year, with an elevated intensity of 18.5% in July. Under the current fishing regime the population could be at risk of collapse, as indicated by the high exploitation rate (E) 0.80

  14. 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.

  15. 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.

  16. Subsidence beneath a playa basin on the Southern High Plains, U. S. A. Evidence from shallow seismic data

    SciTech Connect

    Paine, J.G. )

    1994-02-01

    Shallow seismic data from Sevenmile Basin, a large ephemeral lake (playa) basin in the Texas Panhandle, reveal that subsidence has been an important agent in basin formation. Sevenmile Basin is 5.5 x 3.6 km across and 14 m deep and contains 20 m of lacustrine and eolian sediments that interfinger with the Quaternary Blackwater Draw Formation. Seismic reflection and refraction data were collected from the unlithified and variably saturated clastic sequence beneath Seven-mile Basin to investigate the geological history and hydrogeological framework of playa basins, which recharge the regionally important Ogallala aquifer. Three-layer velocity models provide good solutions for reversed refraction data. Near-surface p-wave velocities (layer 1) range from 349 to 505 m/s, layer 2 velocities range from 806 to 851 m/s, and layer 3 velocities range from 2,037 to 2,161 m/s. Shallow test holes and drillers' logs suggest that layer 1 is composed of playa and upper Blackwater Draw Formation deposits, layer 2 consists of lower Blackwater Draw Formation and upper Ogallala Formation deposits, and layer 3 represents a competent and partly saturated zone near the top of the Ogallala aquifer. Reflection sections show a middle Ogallala reflector, a reflector at the top of Permian or Triassic bedrock, and internal bedrock reflectors that indicate a structural low beneath Sevenmile Basin. Increasing relief with age, from 14 m at the surface to 70 m on the middle Ogallala reflector to 110 m at the base of the Ogallala, is interpreted as evidence of subsidence of underlying Permian evaporite-bearing strata before or during Ogallala deposition. 29 refs., 12 figs., 2 tabs.

  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. Eolian sediments generated by anthropogenic disturbance of playas: human impacts on the geomorphic system and geomorphic impacts on the human system

    NASA Astrophysics Data System (ADS)

    Gill, Thomas E.

    1996-09-01

    In many of the Earth's arid and semiarid lands, saline lakes, playas, and similar landforms are disturbed as a result of human activity. Diversion and/or consumptive use of surface or groundwaters has created the effect of a climate change in numerous drainage basins, resulting in the desiccation of lakes and reactivation of eolian processes at many locations. Playas are natural sites for extensive eolian activity because of the deposition of clastic and chemical sediments in basins by surface water (via fluvial transport) and groundwater (via efflorescence). Wind erosion and deposition of playa sediments has had a major role in the development of landforms and sedimentary units in the present (lunette fields worldwide; Simpson Desert, Australia) and geological past, from the Triassic (Mercia Mudstone, England) to the Quaternary (Lahontan Basin and Cima Volcanic Field, USA). Anthropogenic disturbance or desiccation of playa systems has resulted in the eolian transport of sand (e.g. Lop Nor, China; Konya Basin, Turkey; Rajasthan, India; Kappakoola, Australia; several sites in West Africa) and/or dust (e.g. Aral Sea, Kazakhstan/Uzbekistan; Old Wives Lake, Canada; Kara Bogaz Gol, (ex-)USSR; Lake Texcoco, Mexico; Owens (dry) Lake, Mono Lake and other playas, USA). Typically, this is accomplished by abstraction of water and/or removal of vegetation from terminal lake basins. An extensive review of the literature documents many examples and/or potential examples of such phenomena in numerous nations. The reactivation of eolian processes from closed basins produces air pollution in the form of fugitive dust (naturally occurring compounds released into the atmosphere by human actions), and has significant environmental and economic impacts on human activities in the surrounding areas. Restoration or mitigation of degraded land on or surrounding playas has been accomplished at Lake Texcoco, Kara Bogaz Gol and the Konya Basin, and is being actively implemented at Mono Lake

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  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. Exploring Variability in Acidic Saline Playa Lakes in WA with HyMAP Hyperspectral Data

    NASA Astrophysics Data System (ADS)

    Baldridge, A. M.; Hook, S. J.; Souza Filho, C. R.; Thomson, B. J.; Bridges, N. T.; Crowley, J. K.

    2009-12-01

    Acid saline lakes in Western Australia have been recognized as useful chemical terrestrial analogs for aqueous mineral formation on Mars [e.g., 1]. In these lake systems, large pH and salinity differences are observed both laterally and vertically over scales of a few tens of meters[2, 3]. The variability in these lakes have been offered as an alternate formation mechanism for some of the phyllosilicates and sulfates on Mars, suggesting that these different mineral types may be separated by chemical gradients rather than by temporal boundaries[4]. To assess the ability to detect this variability remotely and to determine the extent of the surface variability, which may not be easily accessible in the field, spectral mapping for two of the acidic saline playa lakes was performed. HyMAP airborne data were acquired in December, 2008, of Lake Gilmore and Lake Chandler in WA. The HyMAP sensors have 126 bands that cover the wavelength range between 0.45 and 2.5 µm. Hyvista Corporation provided atmospherically corrected surface reflectance data at approximately 3m spatial resolution. Using the methodology described by [5] the HyMAP data were analyzed using ENVI to identify spectrally pure endmembers that can be used to distinguish mineralogy in the scene. Relevant (e.g. not roads, water or vegetation) spectral endmembers derived for each scene were identified visually using spectra from the ASTER spectral library[6]. The processing techniques were applied to all flight lines and ultimately a classification map mosaic was produced for selection of relevant and intriguing field sampling sites. The classification maps will be validated using field spectroscopy and visual inspection of representative samples collected from the field sites in October 2009, and laboratory spectroscopy and X-ray diffraction will be performed for further validation. The classification maps confirm variability in mineralogy across the lakes, validating geochemical modeling. There are also some

  7. A playa deposit of pre-Yellow Sands age (upper Rotliegend/Weissliegend) in the Permian of northeast England

    NASA Astrophysics Data System (ADS)

    Turner, Brian R.; Smith, Denys B.

    1997-12-01

    A complexly interbedded thin succession of sandstone, siltstone and mudstone beneath the Permian Yellow Sands Formation (upper Rotliegend/Weissliegend) was cored in a borehole 11 km off the coast of northeast England. The cored strata rest unconformably on fissured Westphalian B mudstone and mainly comprise low-dipping fine- to coarse-grained grey sandstone with unevenly spaced thinner dark-red to grey mudstone beds and laminae. Most of the sandstone beds are moderately to poorly sorted, fine- to very fine-grained subarkoses, with some sublitharenites, and are weakly to strongly cemented by dolomite (predominant), kaolinite and illite; sedimentary structures include subhorizontal plane to wavy lamination, ripple lamination, salt ridges and soft-sediment deformation. The siltstones and mudstones are more uniform in lithology and primary thickness; they contain sandstone-filled desiccation cracks, mudstone saucers and narrow sandstone dykes. Traces of possible former evaporite minerals are concentrated in the sandstones. By comparison with modem desert depositional environments, these strata are interpreted as the deposits of a playa occupying a depression on a stony, deflationary desert surface on a rock pediment or peneplain flanking the ancestral Pennines. The floor of the depression, which probably lay in the capillary fringe just above the contemporary water table, was periodically flooded so as to form a shallow playa lake. Comparable successions beneath the Yellow Sands have not been recorded from surface exposures in northeast England but mudstone beds at this stratigraphical level have been recorded in four other cored offshore boreholes and are presumed to be of similar origin to those described in this study. The stratigraphical position of these deposits suggests that they may be of pre-Yellow Sands age and coeval with or younger than the Basal Permian Breccia. Palynological analysis of mudstone samples from the core reveal the presence of plant material

  8. 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).

  9. Late Holocene evolution of playa lakes in the central Ebro depression based on geophysical surveys and morpho-stratigraphic analysis of lacustrine terraces

    NASA Astrophysics Data System (ADS)

    Gutiérrez, F.; Valero-Garcés, B.; Desir, G.; González-Sampériz, P.; Gutiérrez, M.; Linares, R.; Zarroca, M.; Moreno, A.; Guerrero, J.; Roqué, C.; Arnold, L. J.; Demuro, M.

    2013-08-01

    The origin and morpho-stratigraphic evolution of the largest playa-lake system (La Playa-El Pueyo) in the Bujaraloz-Sástago endorheic area, located in the semiarid central sector of the Ebro Depression, are analysed. The enclosed depressions are developed on gypsiferous Tertiary bedrock and show a prevalent WNW-ESE orientation parallel to the direction of the prevalent strong local wind (Cierzo). Yardangs have been carved in bedrock and unconsolidated terrace deposits in the leeward sector of the largest lake basins. A sequence of three lacustrine terrace levels has been identified by detailed geomorphological mapping. The treads of the upper, middle and lower terrace levels are situated at + 9 m, + 6 m and + 0.5 m above the playa-lake floors, respectively. Seismic refraction and electrical resistivity profiles acquired in La Playa reveal a thin basin fill (~ 2 m) with a planar base. These data allow ruling out the genetic hypothesis for the depressions involving the collapse of large bedrock cavities and support a mixed genesis of combined widespread dissolution and subsidence by groundwater discharge and eolian deflation during dry periods. The 5 m thick deposit of the middle terrace was investigated in hand-dug and backhoe trenches. Six AMS radiocarbon ages from this terrace indicate an aggradation phase between 3.9 ka and ca. 2 ka. These numerical ages yield a maximum average aggradation rate of 2.6 mm/yr and a minimum excavation rate by wind deflation of 3 mm/yr subsequent to the accumulation of the middle terrace. The latter figure compares well with those calculated in several arid regions of the world using yardangs carved in palaeolake deposits. The aggradation phase between 4 and 2 ka is coherent with other Iberian and Mediterranean records showing relatively more humid conditions after 4 ka, including the Iron Ages and the Iberian-Roman Period.

  10. Evaporite-mineral Dusts From a Dry Saline Playa in the Mojave Desert and Bioaccessibility of Their Trace Metals

    NASA Astrophysics Data System (ADS)

    Reynolds, R. L.; Breit, G. N.; Goldstein, H.; Morman, S.; Reheis, M. C.; Yount, J. C.; Bogle, R.; Vogel, J.; Ballantine, J.; King, J.

    2008-12-01

    Evaporite-rich sediments commonly form on the surfaces of dust-emitting dry saline lakes, including wet playas, where the depth to the saturated zone is less than about 4 m. These sediments may contain high levels of toxic metals and metalloids, but many important aspects about these kinds of settings remain poorly known: Conditions that promote and suppress dust emission; chemical relations among ground water, salt- rich crusts, and salt-rich dust; bioaccessibility of metals and metalloids in dust; and controls of human activity and climatic variability on dust emission and on metal contents of dust. A dust-emitting area in the Mojave Desert provides a setting where these factors can be evaluated. The area encompasses Ash Meadows to the north where dilute waters (0.7 mS/cm) both discharge and evaporate and Franklin Lake playa (FLP) about 20 km south where saline ground water (90 mS/cm) evaporates. These features are linked by north-to-south flow of shallow ground water in a confined aquifer beneath Carson Slough that has intermediate salinity (1.5- 16 mS/cm). In ground water at FLP, maximum dissolved concentrations of arsenic (16 mg/L), molybdenum (12 mg/L), selenium (0.7 mg/L), tungsten (0.3 mg/L), and uranium (4 mg/L) are explained by evaporative concentration. Monitoring of dust emission from FLP between March 2005 and April 2008, mainly using digital cameras triggered automatically by wind speeds greater than 4.5 m/s, reveals that aridity suppressed dust emission, whereas wet periods promoted dust emission by generating loose accumulations of salt minerals or thin salt crusts that are vulnerable to wind erosion. Samples of dust taken by a portable wind tunnel and of salt crusts contain highly variable contents of toxic metals and metalloids that have high levels of bioaccessibility when leached in fluids that simulate human gastric, intestinal, and lung fluids, with respective pHs of 1.5, 5.5, and 7.4. The levels of bioaccessible toxic substances correspond

  11. 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

  12. Dynamics of Groundwater Flow at an Alluvial Fan/Playa Margin Interface Based on Inorganic and Isotope Hydrochemistry

    NASA Astrophysics Data System (ADS)

    Vargas, L. M.; Hibbs, B. J.

    2009-12-01

    Mojave Chub (MC) Spring is located at an alluvial fan/playa margin interface between Soda Lake and the Soda Mountains, Mojave Desert. Identifying the source flows at MC Spring provides an opportunity to help managers protect the spring and the Mojave tui chub, a listed endangered species that survives in MC Spring. An alluvial fan formed on the flanks of the Soda Mountains is the likely source of recharge for a relatively dilute (2200 mg/L TDS) groundwater lens. Other groundwaters around the area are strongly mineralized, with salinities ranging from about 3500 mg/L to 30,000 mg/L TDS. Limestone Hill is an isolated carbonate outcrop located between the alluvial fan at Soda Mountains and the phreatic playa at Soda Lake. MC Spring flows from the opposite side of Limestone Hill, and is separated from Soda Mountains and the alluvial fan by Limestone Hill. Analysis of groundwater samples for standard inorganic parameters, chloride/bromide ratios, sulfur isotopes, stable O-H isotopes, and radioisotopes including tritium and carbon 14 identify similar physical, chemical, and age properties at MC Spring and in production wells at the site. Despite salinity variation, most waters have similar oxygen and deuterium stable isotope signatures, indicating that salinity enrichment occurs by evaporite mineral dissolution and not by groundwater evaporation. Tritium is not detected in shallow wells (2 to 5 meters deep) and deeper production wells (10 to 18 meters deep) at the site, despite the fact that the wells are located in an alluvial fan at the flanks of the Soda Mountains. Tritium data suggest sluggish groundwater movement and/or very small amount of active recharge at the Soda Mountains alluvial fan. Carbon 14 is about 70 to 80 percent modern carbon (PMC) in the shallow piezometers at the site but is only about 48 PMC in the deeper production wells, and about 45 PMC at MC Spring. These data and aquifer test data suggest a common source of recharge in the Soda Mountains

  13. Radar signatures of sediment availability-limited dune-fields and playas on Earth as a Titan analog.

    NASA Astrophysics Data System (ADS)

    Epps, J. C.; Ewing, R. C.

    2015-12-01

    Large areas within the dune fields that mantle the equatorial regions of Saturn's moon, Titan appear to be sand availability-limited. These areas occur at dune field margins and in the inferred lee-side of topographic obstacles within the dune fields. Viewed with Cassini radar, these areas are lighter-toned than radar dark dunes, which implies radar scattering off of a rough surface. Otherwise, these areas have no geomorphologic structure visible at the spatial resolution of the Cassini radar. Within dune environments rough, sediment-availability limited surfaces can occur as pebble or cobble lag, surface crusts, evaporite polygons, dessication cracks and dune-cross-stratification. This study aims to better understand radar-response to a range of sediment availability-limited surfaces in dune environments using terrestrial spaceborne synthetic aperture radar (SAR) acquisitions. We primarily target playas and interdune-areas in western North America, southern Africa and the Middle East. As a means for multi-temporal comparison between satellite platform acquisitions, the SAR backscatter coefficient, σ0, has been used as a measure of the radar return intensity (brightness) and the surface roughness. SAR systems measure the ratio between the power of the pulse transmitted and that of the echo received as projected into the slant-range geometry. Geometric and radiometric calibration of the backscatter values are necessary for inter-comparison of radar images acquired with different sensors, or even of images obtained by the same sensor if acquired in different modes and look geometries. In light of this, this investigation has considered and fused a number of SAR datasets from SRTM SIR-C/X-SAR, ERS-1/2, Envisat, and Radarsat as a means for spatial and temporal variation of σ0. Preliminary statistical analysis of the backscatter coefficient shows decadal and seasonal trends in the variation of surface roughness over the temporal range of the data sets. Further

  14. Chihuahuan desert flora of La Calera, Municipio de Agua Prieta, Sonora, Mexico

    Treesearch

    Ana Lilia Reina-Guerrero; Thomas R. Van Devender

    2013-01-01

    A total of 555 plant collections were made on 20 trips in 2002-2008 to La Calera area in the Sierra Anibácachi, Municipio de Agua Prieta, 11.3 km south of the Arizona border (31°13’59”N 109°37’53”W, elevation range from 1220 m to 1539 m) in northeastern Sonora. Chihuahuan desertscrub on limestone substrates is dominated by creosotebush (Larrrea divaricata), Chihuahuan...

  15. 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.

  16. 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.

  17. [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.

  18. 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

  19. Diagenesis of Paleozoic playa-lake and ephemeral-stream deposits from the Pimenta Bueno Formation, Siluro-Devonian (?) of the Parecis Basin, central Brazil

    NASA Astrophysics Data System (ADS)

    Goldberg, K.; Morad, S.; Al-Aasm, I. S.; De Ros, L. F.

    2011-07-01

    The Parecis Basin is a large intracratonic rift located in central Brazil and filled with Paleozoic carbonate, evaporite and siliciclastic sediments. The occurrence of gas seeps has recently attracted significant exploration interest by the Brazilian petroleum agency and by Petrobras. The continuously cored PB-01-RO well provided the first opportunity to study the depositional environments, diagenetic evolution and hydrocarbon potential of the largely unknown sedimentary successions of the Parecis Basin. The cored lithologies, belonging to the Siluro-Devonian (?) Pimenta Bueno Formation, are interpreted as deposited in playa-lake and ephemeral-stream environments. The deposits display a strong facies control on the diagenetic mineral assemblages and evolution. Diagenetic minerals in the ephemeral-stream deposits include eogenetic hematite and smectitic clay coats and quartz cement, and the mesogenetic process includes precipitation of sulfates (anhydrite and barite) and carbonates (calcite, dolomite and kutnahorite-ankerite-huntite), followed by partial dissolution of these carbonates and sulfates, and of feldspar grains. Telogenetic processes include the precipitation of hematite and kaolinite within secondary pores, and the replacement of anhydrite by gypsum. A second burial phase and mesodiagenesis is indicated by the precipitation of discrete K-feldspar crystals within moldic pores after dissolved feldspars, and by the illitization of etched, telogenetic kaolinite. The playa-lake deposits show early diagenetic dolomitization of lime mud, precipitation of anhydrite nodules and extensive silicification. The anhydrite nodules were replaced by gypsum and chalcedony during telodiagenesis. Potential source rocks are locally represented by organic shales. The fluvial sandstones show fair reservoir quality and limited compaction, as indicated by their intergranular volume, suggesting that the succession has undergone moderate burial. Potential seals for hydrocarbon

  20. 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.

  1. 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).

  2. Alluvial sediment or playas: What is the dominant source of sand and silt in desert soil vesicular A horizons, southwest USA

    NASA Astrophysics Data System (ADS)

    Sweeney, Mark R.; McDonald, Eric V.; Markley, Christopher E.

    2013-03-01

    Vesicular A (Av) soil horizons form beneath desert pavements from the accretion of aeolian sediment (dust) commonly thought to be derived primarily from desiccating pluvial lakes and playas, with contributions from ephemeral washes and alluvial fans. Particle size distributions of Av horizons are typically bimodal with primary modes of very fine silt and fine sand, suggesting that the horizon matrix is derived from multiple sources. Here we conduct detailed chemical and physical analysis of both Av horizon soil samples and potential sources of aeolian sediment to better constrain the relative contributions of dust associated with the development of Av horizons. Geochemical data from both sand (125-250 µm) and silt (2-32 µm) fractions in Av horizons and potential dust sources in the eastern Mojave Desert and western Sonora Desert, USA, point to large contributions from nearby sources including distal alluvial fans and washes, and comparably lower contributions from regional sources such as playas. The silt mode is derived from suspension transport of dust, and the fine sand mode is derived from saltating sand. The desiccation of pluvial lakes in the Mojave Desert is commonly believed to have driven episodes of aeolian activity, contributing to sand dunes and Av horizon formation. We propose that alluvial fans and washes are underappreciated as desert dust sources and that pulses of dust from late Pleistocene and Holocene alluvial fans dwarfed pulses of dust from desiccating pluvial lakes in the eastern Mojave Desert.

  3. Controls on the chemical composition of saline surface crusts and emitted dust from a wet playa in the Mojave Desert (USA)

    USGS Publications Warehouse

    Goldstein, Harland L.; Breit, George N.; Reynolds, Richard L.

    2017-01-01

    Saline-surface crusts and their compositions at ephemeral, dry, and drying lakes are important products of arid-land processes. Detailed understanding is lacking, however, about interactions among locally variable hydrogeologic conditions, compositional control of groundwater on vadose zone and surface salts, and dust composition. Chemical and physical data from groundwater, sediments, and salts reveal compositional controls on saline-surface crusts across a wet playa, Mojave Desert, with bearing on similar settings elsewhere. The compositions of chemically and isotopically distinctive shallow (<3 m) water masses are recorded in the composition of associated salts. In areas with deeper and more saline groundwater, however, not all ions are transported through the vadose zone. Retention of arsenic and other elements in the vadose zone diminishes the concentrations of potentially toxic elements in surface salts, but creates a reservoir of these elements that may be brought to the surface during wetter conditions or by human disturbance. Selective wind-erosion loss of sulfate salts was identified by the compositional contrast between surface salt crusts and underlying groundwater. At the sub-basin scale, compositional links exist among groundwater, salt crusts, and dust from wet playas. Across the study basin, however, lateral variations in groundwater and solid-salt compositions are produced by hydrogeologic heterogeneity.

  4. 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).

  5. 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

  6. 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

  7. 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

  8. 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.

  9. The chemistry of playa-lake-sediments as a tool for the reconstruction of Holocene environmental conditions - a case study from the central Ebro basin

    NASA Astrophysics Data System (ADS)

    Schütt, Brigitta

    The focus of the presented study is the reconstruction of the Holocene limnic and drainage basin conditions of the Laguna de Jabonera, a today playa-lake-system in the Desierto de Calanda, central Ebro Basin, using the inorganic characters of the lacustrine sediments. Mineralogical fabric helped to reconstruct the overall geomorphic processes and gives clues to the synsedimentary limnic environment (paleosalinity). The chemical composition of the lacustrine sediments largely reflects the mineralogical composition, but the higher resolution of the geochemical data compared to the mineralogical data enables to stratigraphically split the extracted core profile into three stratigraphic units. Supplementally, it is demonstrated that Statistics between chemical compounds point to the synsedimentary intensity of weathering and soil forming processes. As for the lacustrine sediments investigated there are no data yet available a preliminary chronological framework is derived by comparison with results from neighbouring areas. Based on this the hypothesis is put forward that during the socalled Little Ice Age subhumid to dry-subhumid environmental conditions occurred. Also possibly during the late Subboreal distinct wetter environmental conditions than today prevailed. Additionally, it is demonstrated that in the most recent past human impact is causing increased erosion rates and, thus, increased deposition of detritals in the most recent lacustrine sediments.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. End-Pleistocene to Holocene paleoenvironmental record from piston corer samples and the challenge of stratigraphic correlation of playa sediment data with a connected alluvial apron from Damghan Basin, Iran

    NASA Astrophysics Data System (ADS)

    Büdel, Christian; Hoelzmann, Philipp; Wennrich, Volker; Majid Padashi, Sajed; Baumhauer, Roland

    2015-04-01

    The study yields a first characterization and correlation of the end-Pleistocene to Holocene sediment archive of playa and playa lake deposits in the Damghan Basin, northern Iran. The Basin sediments are deposited since Mio- and Pliocene, which is valid for the connected alluvial fans, too. These are covering the area between the playa and mountains and while prograding from the mountain ranges they deliver gravels and fine-sediments to the basins sink. The processes on the studied alluvial apron are described and dated already and can be explained in seven morphodynamic phases, which are linked to a general lake level high-stand in north-east Iran at about 8000-9000 years ago. If and how these phases are passed on from the alluvial record down to the playa sediment record is aim of this study. Today the salt pans margins are highly affected by salt tectonic drifting and access was suboptimal. Only here drilling could be performed through about 280 centimeters of salt-crust unfrequently intercalated with loamy layers. For yielding undisturbed playa sediment records sampling was performed with inliner-tubes deployed in a piston corer (Kullenberg type). Thus at two different drilling sites in summation seven cores could be taken, down to a maximum depth of 129 cm and 1000 cm. Back in Germany the cores had been opened and initially described, photographed and optically scanned with a core logger. Regarding future studies, the aim was a best possible comprehensive documentation of the cores. Therefore basically grainsize measurements (laser diffraction), multi element analyses (XRF, ICP-OES, titrimetry) and mineralogical measurements (XRD) had been deployed on samples taken from every single previously identified layer. Continuous elemental data was secured by use of a XRF-scanning core logger. The sedimentological description together with laboratory element analyses shows saline conditions in the first three meters coincide with general coarser grain sizes. The next

  15. [Reproductive pattern and mean size of sexual maturity of female lobsters Panulirus gracilis (Decapoda: Palinuridae) in Playa Lagarto, Guanacaste, Costa Rica].

    PubMed

    Naranjo Madrigal, Helven

    2012-12-01

    The lobster P. gracilis is important as a fishery resource and also contributes to food security of fishers in coastal communities in the North Pacific of Costa Rica. Due to the importance of updating knowledge related to the reproductive pattern of this species, we analyzed 357 specimens of female lobsters caught by the fishing methods of "hookah" and lung diving, from November 2007 to October 2008 in Playa Lagarto. Furthermore, we examined the size composition by depth; monthly pattern of reproductive activity (RAI) associated with the relative increase in sea surface temperature, and also the mean size at maturity using Generalized Linear Models. Four physiological states of sexual maturity showed that females with no signs of mating or sexual maturity have a minimum mean size of 62.3mm of cephalothorax length (CL). There are characteristics of functional maturity from very small sizes ranging from 30 to 50mm CL, being the smallest berried female reported for this specie of 35.8mm CL and the highest percentage of mature females between 70 and 80mm CL. Percentages of RAI remained above 50% during the year except October and January. In addition, it observed an increase in the RAI that started from April and continued until August associated with a relative increase in temperature on March, although the correlation was not significant (r2=0.49, p>0.05). It is possible that the low mean size at maturity (70.2mm LC) for P. gracilis in this region is related to the fishing activity. It recommends the establishment of a ban in the region of at least five months (April-August) in order to protect the reproductive seasonality of the species and to promote a recruitment increase in the fishing areas.

  16. The balance between deposition and subsidence (tectonics) in a rift basin playa and its effect on the climatic record of an area: Evidence from Bristol Dry Lake, California

    SciTech Connect

    Rosen, M.R. )

    1991-03-01

    Two continuous core intervals drilled in Bristol Dry Lake, a large (150 km{sup 2}) playa in the central Mojave Desert of California, penetrated over 500 m of sediment and did not reach basement. The repetitious nature of the alternating shallow brine pond halite and siliciclastic and the consistency of the carbonate isotopic data from the surface and core indicate a relatively stable brine composition for most of the history of Bristol Dry Lake. All sedimentary structures and primary halite fabrics in the core indicate shallow-water, brine-pond halite alternated with halite-saturated siliciclastic muds in the basin center. A delicate balance of subsidence and mechanical and chemical deposition of evaporite and siliciclastic minerals was necessary to maintain the largely ephemeral lake environment of deposition through over 550 m of basin fill. The alternating brine pond/saline lake setting in Bristol Dry Lake is not directly related to climatic influences, and the sediments do not record major climatic events demonstrated in other closed-basin lakes. The reason for this insensitivity to climatic events is explained by the interior location of the basin, the low relief of the mountains surrounding the catchment, the large surface area of the catchment, and the low average sedimentation rates. All of the above criteria are at least partially controlled by the tectonics of the area, which, in turn, affect the sedimentation rate and supply water to the basin. Therefore, it is important to consider the influence of the above factors in determining global versus local, or regional, climate curves for a particular basin.

  17. Linking playa surface dust emission potential to feedbacks between surface moisture and salt crust expansion through high resolution terrestrial laser scanning measurements

    NASA Astrophysics Data System (ADS)

    Nield, J. M.; King, J.; Wiggs, G.

    2012-12-01

    The dust emissivity of salt pans (or playas) can be significant but is controlled by interactions between wind erosivity, surface moisture, salt chemistry and crust morphology. These surface properties influence the aeolian transport threshold and can be highly variable over both short temporal and spatial scales. In the past, field studies have been hampered by practical difficulties in accurately measuring properties controlling sediment availability at the surface in high resolution. Studies typically therefore, have investigated large scale monthly or seasonal change using remote sensing and assume a homogeneous surface when predicting dust emissivity. Here we present the first high resolution measurements (sub-cm) of salt crust expansion related to changes in diurnal moisture over daily and weekly time periods using terrestrial laser scanning (TLS, ground-based LiDAR) on Sua Pan, Botswana. The TLS measures both elevation and relative surface moisture change simultaneously, without disturbing the surface. Measurement sequences enable the variability in aeolian sediment availability to be quantified along with temporal feedbacks associated with crust degradation. On crusts with well-developed polygon ridges (high aerodynamic and surface roughness), daily surface expansion was greater than 30mm. The greatest surface change occurred overnight on the upper, exposed sections of the ridges, particularly when surface temperatures dropping below 10°C. These areas also experienced the greatest moisture variation and became increasingly moist overnight in response to an increase in relative humidity. In contrast, during daylight hours, the ridge areas were drier than the lower lying inter-ridge areas. Positive feedbacks between surface topography and moisture reinforced the maximum diurnal moisture variation at ridge peaks, encouraging crust thrusting due to overnight salt hydration, further enhancing the surface, and therefore, aerodynamic roughness. These feedbacks

  18. 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

  19. 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

  20. 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.

  1. 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

  2. Magnetostratigraphic and Stable Isotopic Analysis of Playa-Lacustrine Deposits in the Qaidam Basin, China: Implications for Climate-Environmental Changes and Orbital Forcing Mechanisms During the Plio-Quaternary Transition

    NASA Astrophysics Data System (ADS)

    Moe, A. E.; Heermance, R. V., III; Nie, J.; Li, L.; Kreuzer, R.; Garzione, C. N.; Zeng, L.; Su, Q.

    2016-12-01

    Recently deformed and exposed strata in the Qaidam Basin provide an ideal opportunity to study environmental changes, revealing climate variations over the past few million years. We present new sedimentological descriptions, magnetostratigraphy, and δ18O data to investigate the timing of lake level fluctuations in the western Qaidam Basin. Approximately 740 m of shale, limestone, and gypsum provide a complete record of playa-lacustrine deposition. The lower 477 m were sampled for magnetostratigraphic and isotopic analysis. Magnetostratigraphy defines 9 magnetozones that correlate between 3.6 Ma and 1.8 Ma. Stable isotope data from the lower 220 m implies cyclic changes throughout the section. Stratigraphic and δ18O observations combined with our age model provides a history of hydrologic changes within the basin. Prior to 3.5 Ma, recurring strata of gypsum capped mudstone indicate cyclic lake-desiccation with 20 kyr periodicity. From 3.5 Ma - 3.2 Ma, a decrease in gypsum shows 60 kyr - 100 kyr lake-desiccation cycles, suggesting higher lake levels and a more humid climate. Similarly, stable oxygen isotope data reveal strong 23 kyr precessional cycles and 100 kyr eccentricity cycles before 3.4 Ma, followed by 60 kyr and 100 kyr dominant cycles between 3.3 and 3.1 Ma. After 3.2 Ma, stratigraphic cycles double in duration to 40 kyr; further analysis of δ18O will confirm these results. At 2.8 Ma, a lack of gypsum coupled with the appearance of frequent limestone beds suggests a change in the hydrology at the onset of Northern Hemisphere glaciation, due either to climate change or to tectonic partitioning of the lake caused by growth of an adjacent fold. A decrease in the sedimentation rate from 0.28 mm/yr to 0.19 mm/yr occurs at the Plio-Quaternary Boundary (2.6 Ma), while gypsum beds reappear and increase up-section. By 2.2 Ma, gypsiferous mudstone with gypsum beds dominate and attest to the influence of hyper-arid conditions, similar to those observed in the

  3. 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...

  4. Mysterious Roving Rocks of Racetrack Playa

    NASA Image and Video Library

    2010-06-23

    A small level is used to see if the trail is tilted upward or downward. In most cases where a rock has moved, the trail is tilted very slightly uphill, but the interns don't think this has a noticeable effect on the movement. The compass is included for scale. Photo credit: Leva McIntire, NASA/GSFC/LPSA intern NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

  5. Mysterious Roving Rocks of Racetrack Playa

    NASA Image and Video Library

    2010-06-23

    This group photo of the LPSA interns and trip leaders was taken at Tea Kettle Junction in Death Valley, Calif. (Standing on left side, left to right): Kristopher Schwebler, Valerie Fox, Emily Kopp, Kyle Yawn, Dan Burger, Ian Schoch, Devon Miller; (left to right, sitting) Justin Wilde, Jessica Marbourg, Maggie McAdam (a trip leader), Leva McIntire, Ann Parsons (a trip leader), Mindy Krzykowski, Emma McKinney, Cynthia Cheung (LPSA principal investigator and a trip leader), George Fercana; (standing on right side): Kynan Rilee, Gregory Romine, Clint Naquin, Gunther Kletetschka (a trip leader), Andrew Ryan, and in the very back, Brian Jackson (a trip leader). Photo credit: NASA/GSFC/ Leva McIntire/LPSA intern NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

  6. 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.

  7. 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.

  8. Delineating Playas in the Arid Southwest: A Literature Review

    DTIC Science & Technology

    2001-04-01

    subterminalis, Suaeda fruticos, S. torreyana, Sarcobatus vermiculatus, Allenrolfea oc- cidentalis, and Nitrophila occidentalis. (3) Alkalai meadow and...successively upward. Pioneer plants such as Kochia californica or Suaeda fruticos may be initial colonizers; as aeolian material develops around them they may...such as Allenrolfea occidentalis, Nitrophi- la occidentalis, Salicornia subterminalis, Suaeda spp., and Sarcobatus vermiculatus as representatives of

  9. 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.

  10. 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…

  11. 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.

  12. 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.

  13. Comparison if seepage rates in playa lakes in grassland and cropland basins, Texas High Plains

    USDA-ARS?s Scientific Manuscript database

    Two sorghum isolines, a wild type (BTx 623) and an erect leaf mutant line (ERL 20) isolated from the wild type were field grown in rectilinear arrays at low (25 plants m-2) and high (12 plants/m-2) densities with sub-surface drip irrigation in an effort to eliminate confounding drought effects. Cano...

  14. Prokaryotic diversity in Aran-Bidgol salt lake, the largest hypersaline playa in Iran.

    PubMed

    Makhdoumi-Kakhki, Ali; Amoozegar, Mohammad Ali; Kazemi, Bahram; Pašić, Lejla; Ventosa, Antonio

    2012-01-01

    Prokaryotic diversity in Aran-Bidgol salt lake, a thalasohaline lake in Iran, was studied by fluorescence in situ hybridization (FISH), cultivation techniques, denaturing gradient gel electrophoresis (DGGE) of PCR-amplified fragments of 16S rRNA genes and 16S rRNA gene clone library analysis. Viable counts obtained (2.5-4 × 10(6) cells mL(-1)) were similar to total cell abundance in the lake determined by DAPI direct count (3-4×10(7) cells mL(-1)). The proportion of Bacteria to Archaea in the community detectable by FISH was unexpectedly high and ranged between 1:3 and 1:2. We analyzed 101 archaeal isolates and found that most belonged to the genera Halorubrum (55%) and Haloarcula (18%). Eleven bacterial isolates obtained in pure culture were affiliated with the genera Salinibacter (18.7%), Salicola (18.7%) and Rhodovibrio (35.3%). Analysis of inserts of 100 clones from the eight 16S rRNA clone libraries constructed revealed 37 OTUs. The majority (63%) of these sequences were not related to any previously identified taxa. Within this sampling effort we most frequently retrieved phylotypes related to Halorhabdus (16% of archaeal sequences obtained) and Salinibacter (36% of bacterial sequences obtained). Other prokaryotic groups that were abundant included representatives of Haloquadratum, the anaerobic genera Halanaerobium and Halocella, purple sulfur bacteria of the genus Halorhodospira and Cyanobacteria.

  15. Disruptive Effects of Colorful vs. Non-colorful Play Area on Structured Play-A Pilot Study with Preschoolers.

    PubMed

    Stern-Ellran, Keren; Zilcha-Mano, Sigal; Sebba, Rachel; Levit Binnun, Nava

    2016-01-01

    To contribute to young children's development, sensory enrichment is often provided via colorful play areas. However, little is known about the effects of colorful environments on children while they engage in age-appropriate tasks and games. Studies in adults suggest that aspects of color can distract attention and impair performance, and children are known to have less developed attentional and executive abilities than adults. Preliminary studies conducted in children aged 5-8 suggest that the colorfulness of both distal (e.g., wall decorations) and proximal (e.g., the surface of the desktop) environments can have a disruptive effect on children's performance. The present research seeks to extend the previous studies to an even younger age group and focus on proximal colorfulness. With a sample of 15 pre-schoolers (3-4 years old) we examined whether a colorful play surface compared to a non-colorful (white) play surface would affect engagement in developmentally appropriate structured play. Our pilot findings suggest that a colorful play surface interfered with preschoolers' structured play, inducing more behaviors indicating disruption in task execution compared with a non-colorful play surface. The implications of the current study for practice and further research are discussed.

  16. A 3,000-year quantitative drought record derived from XRF element data from a south Texas playa

    NASA Astrophysics Data System (ADS)

    Livsey, D. N.; Simms, A.; Hangsterfer, A.; Nisbet, R.; DeWitt, R.

    2013-12-01

    Recent droughts throughout the central United States highlight the need for a better understanding of the past frequency and severity of drought occurrence. Current records of past drought for the south Texas coast are derived from tree-ring data that span approximately the last 900 years before present (BP). In this study we utilize a supervised learning routine to create a transfer function between X-Ray Fluorescence (XRF) derived elemental data from Laguna Salada, Texas core LS10-02 to a locally derived tree-ring drought record. From this transfer function the 900 BP tree-ring drought record was extended to 3,000 BP. The supervised learning routine was trained on the first 100 years of XRF element data and tree-ring drought data to create the transfer function and training data set output. The model was then projected from the XRF elemental data for the next 800 years to create a deployed data set output and to test the transfer function parameters. The coefficients of determination between the model output and observed values are 0.77 and 0.70 for the 100-year training data set and 900-year deployed data set respectively. Given the relatively high coefficients of determination for both the training data set and deployed data set we interpret the model parameters are fairly robust and that a high-resolution drought record can be derived from the XRF element data. These results indicate that XRF element data can be used as a quantitative tool to reconstruct past drought records.

  17. 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.

  18. A preliminary floristic inventory in the Sierra de Mazatan, Municipios of Ures and Mazatan, Sonora, Mexico

    Treesearch

    Jose Jesus Sanchez-Escalante; Manuel Espericueta-Betancourt; Reyna Amanda Castillo-Gamez

    2005-01-01

    Presently, the flora of the Sierra de Mazatán contains 357 species of vascular plants distributed in 248 genera and 80 families. The families with the most species are Asteraceae (48), Fabaceae (45), Poaceae (28), Euphorbiaceae (18), and Acanthaceae, Cactaceae, Scrophulariaceae, and Solanaceae (11 each). The results show that the flora of the Sierra de Mazat...

  19. [Venezuelan equine encephalitis. Determination of antibodies in the human population of Municipio Mirand, Estado Zulia, Venezuela].

    PubMed

    Ryder, S; Núñez-Camargo, J; Rangel, P; Añez, F

    1993-01-01

    With the purpose of determining antibodies prevalence against Venezuelan Equine Encephalitis Virus in the population of Puertos de Altagracia and Sabaneta de Palmas of Miranda county, Zulia State, Venezuela, 199 subjects were studied: 57 from Puertos de Altagracia and 142 from Sabaneta de Palmas. They were classified in older (42.78%) and younger (57.2%) than 15 years. The blood specimens were processed for Hemagglutination Inhibition Test using EEV antigen Goajira strain at pH 6.5. We found that all 57 specimens from Puertos de Altagracia were negative, whereas of 142 specimens from Sabaneta de Palmas 17 were positive (11.97%). Of these, one was from a subject less than 15 years-old (5.85%) and 16 from individuals more than 15 years-old (94.15%). Positive titers were higher than 1:160 in 80% of cases. Being Sabaneta de Palmas one of the most affected areas in the 1962 epidemic in the Miranda county and keeping the affected ones high positivity with elevated titers, we conclude that this population could represent an enzootic zone similar to Paez county where a similar situation, of high positivity and elevated titers, many years after the last epidemic occurred in that area, has been described.

  20. Seasonality of births in a rural Zapotec municipio, 1945-1970.

    PubMed

    Malina, R M; Himes, J H

    1977-05-01

    The monthly distribution of live births were analyzed over a 26-year period from 1945-70 for a rural Zapotec-speaking community in Oaxaca, Mexico. Monthly distributions of births were not what would be expected by chance (p.001). High monthly percentages of births coincided closely with the rainy season in the Oaxaca Valley. The number of births during the rainy season exceeded that which was expected, while the number of births during the dry season was less than expected (p.001). Ethnographic observations for Zapotec communities suggest that the seasonal distribution of births may reflect the cultural pattern associated with the annual agricultural cycle. The 3 highest birth months were June, July, and August. Much rain falls in June and July after the crops have been planted in May. There is much anxiety about the rain and the crops which decreases sexual activity and fertility. Clinical observations indicate anxiety as a significant factor in male infertility.

  1. A comparison of in-situ aircraft measurements of carbon dioxide to GOSAT data measured over Railroad Valley playa, Nevada, USA

    NASA Astrophysics Data System (ADS)

    Tadić, J. M.; Loewenstein, M.; Frankenberg, C.; Iraci, L. T.; Yates, E. L.; Gore, W.; Kuze, A.

    2012-08-01

    In this paper we report vertical profiles of CO2 measured with a cavity ring-down spectrometer (CRDS, Picarro, Inc., 2301-m) on a research aircraft from near ground level to 8 km above mean sea level (a.m.s.l.). The airborne platform employed in this study is an Alpha Jet aircraft operated from NASA Ames Research Center. Flights were undertaken to Railroad Valley, Nevada, USA, to coincide with overpasses of the Greenhouse Gases Observing Satellite (GOSAT). Ground based CO2 was simultaneously measured using CRDS, also at the time and location of the airborne and satellite measurements. Results of three GOSAT coordinated aircraft profiles and ground based measurements in June 2011 are presented and discussed in this paper. The accuracy of the CO2 measurements has been determined based upon laboratory calibrations (WMO traceable standard) and pressure/temperature flight simulations in a test chamber. The 2-σ error bars for the CO2 data presented here are ± 0.4 ppm. Our column CO2 measurements, which include about 85% of the tropospheric mass, are extrapolated, using two different techniques, to include the remainder of the tropospheric and stratospheric CO2. The data are then analyzed using the ACOS (Atmospheric CO2 observations from space; JPL algorithm used to analyze XCO2 from GOSAT data) averaging kernels. ACOS version 2.9 is used to interpret the GOSAT data in a collaborative effort between JPL and the GOSAT team. Column averaged CO2, XCO2, measured by GOSAT and analyzed from our data ranged from 388.1 to 390.5 ppm. Values of XCO2 determined from our Alpha Jet measurements and from the GOSAT on three overflight days agree within 1 ppm or better (<0.3%).

  2. Application of a Combined Measurement and Modeling Method to Quantify Windblown Dust Emissions from the Exposed Playa at Mono Lake, California.

    PubMed

    Ono, Duane; Kiddoo, Phill; Howard, Christopher; Davis, Guy; Richmond, Kenneth

    2011-10-01

    Particulate matter ≤10 μm (PM10) emissions due to wind erosion can vary dramatically with changing surface conditions. Crust formation, mechanical disturbance, soil texture, moisture, and chemical content of the soil can affect the amount of dust emitted during a wind event. A refined method of quantifying windblown dust emissions was applied at Mono Lake, CA, to account for changing surface conditions. This method used a combination of real-time sand flux monitoring, ambient PM10 monitoring, and dispersion modeling to estimate dust emissions and their downwind impact. The method identified periods with high emissions and periods when the surface was stable (no sand flux), even though winds may have been high. A network of 25 Cox sand catchers (CSCs) was used to measure the mass of saltating particles to estimate sand flux rates across a 2-km(2) area. Two electronic sensors (Sensits) were used to time-resolve the CSC sand mass to estimate hourly sand flux rates, and a perimeter tapered element oscillating microbalance (TEOM) monitor measured hourly PM10 concentrations. Hourly sand flux rates were related by dispersion modeling to hourly PM10 concentrations to back-calculate the ratio of vertical PM10 flux to horizontal sand flux (K-factors). Geometric mean K-factor values (K f) were found to change seasonally, ranging from 1.3 × 10(-5) to 5.1 × 10(-5) for sand flux measured at 15 cm above the surface (q 15). Hourly PM10 emissions, F, were calculated by applying seasonal K-factors to sand flux measurements (F = K f × q 15). The maximum hourly PM10 emission rate from the study area was 76 g/m(2)·hr (10-m wind speed = 23.5 m/sec). Maximum daily PM10 emissions were estimated at 450 g/m(2)·day, and annual emissions at 1095 g/m(2)·yr. Hourly PM10 emissions were used by the U.S. Environmental Protection Agency (EPA) guideline AERMOD dispersion model to estimate downwind ambient impacts. Model predictions compared well with monitor concentrations, with hourly PM10 ranging from 16 to over 60,000 μg/m(3) (slope = 0.89, R (2) = 0.77). [Box: see text].

  3. Application of a combined measurement and modeling method to quantify windblown dust emissions from the exposed playa at Mono Lake, California.

    PubMed

    Ono, Duane; Kiddoo, Phill; Howard, Christopher; Davis, Guy; Richmond, Kenneth

    2011-10-01

    Particulate matter < or =10 microm (PM10) emissions due to wind erosion can vary dramatically with changing surface conditions. Crust formation, mechanical disturbance, soil texture, moisture, and chemical content of the soil can affect the amount of dust emitted during a wind event. A refined method of quantifying windblown dust emissions was applied at Mono Lake, CA, to account for changing surface conditions. This method used a combination of real-time sand flux monitoring, ambient PM10 monitoring, and dispersion modeling to estimate dust emissions and their downwind impact. The method identified periods with high emissions and periods when the surface was stable (no sand flux), even though winds may have been high. A network of 25 Cox sand catchers (CSCs) was used to measure the mass of saltating particles to estimate sand flux rates across a 2-km2 area. Two electronic sensors (Sensits) were used to time-resolve the CSC sand mass to estimate hourly sand flux rates, and a perimeter tapered element oscillating microbalance (TEOM) monitor measured hourly PM10 concentrations. Hourly sand flux rates were related by dispersion modeling to hourly PM10 concentrations to back-calculate the ratio of vertical PM10 flux to horizontal sand flux (K-factors). Geometric mean K-factor values (K(f)) were found to change seasonally, ranging from 1.3 x 10(-5) to 5.1 x 10(-5) for sand flux measured at 15 cm above the surface (q15). Hourly PM10 emissions, F, were calculated by applying seasonal K-factors to sand flux measurements (F = K(f) x q15). The maximum hourly PM10 emission rate from the study area was 76 g/m2 x hr (10-m wind speed = 23.5 m/sec). Maximum daily PM10 emissions were estimated at 450 g/m2 x day, and annual emissions at 1095 g/m2 x yr. Hourly PM10 emissions were used by the U.S. Environmental Protection Agency (EPA) guideline AERMOD dispersion model to estimate downwind ambient impacts. Model predictions compared well with monitor concentrations, with hourly PM10 ranging from 16 to over 60,000 microg/m3 (slope = 0.89, R2 = 0.77).

  4. Chemical evolution of shallow playa groundwater in response to post-pluvial isostatic rebound, Honey Lake Basin, California-Nevada, USA

    NASA Astrophysics Data System (ADS)

    Mayo, Alan L.; Henderson, Rachel M.; Tingey, David; Webber, William

    2010-05-01

    The 1,750-km2 endorheic Honey Lake basin (California-Nevada, USA) was part of the 22,000-km2 Pleistocene Lake Lahontan pluvial lake system which existed between 5,000 and 40,000 years BP. The basin consists of two subbasins separated by a low elevation divide. Groundwater in the western subbasin has a maximum total dissolved solids (TDS) content of only ˜1,300 mg/L; however eastern subbasin groundwater has a maximum TDS of ˜46,000 mg/L. This TDS distribution is unexpected because 94% of surface water TDS loading is to the western subbasin. In situ reactions and upwelling thermal groundwater contributing to groundwater chemistry were modeled using NETPATH. The TDS difference between the subbasins is attributed to post-Lake Lahontan isostatic rebound about 13,000 years ago. Prior to rebound the subbasins did not exist and the low point of the basin was in the eastern area where hydraulic isolation from the larger Lake Lahontan and frequent desiccation of the basin surface water resulted in evaporite mineral deposition in accumulating sediments. After rebound, the terminal sink for most surface water shifted to the western subbasin. Although most closed basins have not been impacted by isostatic rebound, results of this investigation demonstrate how tectonic evolution can impact the distribution of soluble minerals accumulating in shallow basins.

  5. 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 ...

  6. 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.

  7. [Occupational accidents in Municipio Maracaibo, Estado Zulia, Venezuela, 1979-1990. Determination of the frequency and risk factors which play a role in their production].

    PubMed

    Fernández-D'Pool, J; Montero-Proaño, G

    1993-01-01

    During the period of 1979-1990 job-related injuries were studied in Maracaibo, Zulia state, in order to analyze frequencies and causes. This information was obtained from annual reports on job-related injuries Form Number 15-411 of the Venezuelan Institute of Social Security (IVSS) which has been implemented nationally since 1982. Accidents that caused loss of man-hours were considered; variables considered were: age, risk category, day of the week, work shift, month, type of accident, agent, type of lesion, mechanical cause, body part affected and type of the activity in which the company is involved. The results were expressed as absolute values (mean +/- SE) and relative values. The mean accidents/year was 1651 +/- 177.97, most of them occurring in the age groups of 20-29 years (368.8) and 30-39 years (359.8). The triannual mean rate was higher for the group of the non-serious accidents (50%). Tuesday was the day of higher accidental incidence (22%) in addition to the morning shift between 9 and 11 hours (55%). Manufacturing was the economic activity most affected (43%). The most common causative agents were materials, substances and radiations (35%). The use of defective tools were the most frequent causes of mechanical accidents (31%). Upper limbs (46%) and between the type of lesion contusions or/and bruises (53%). It was concluded that, although the number of workers and accidents slowly diminished, the accidents rate slightly increased.

  8. 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…

  9. 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…

  10. Stereo Pair: Patagonia, Argentina

    NASA Image and Video Library

    2000-06-29

    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.

  11. 40 CFR 117.1 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    .... Wetlands generally included playa lakes, swamps, marshes, bogs, and similar areas such as sloughs, prairie potholes, wet meadows, prairie river overflows, mudflats, and natural ponds): Provided, That...

  12. 40 CFR 117.1 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    .... Wetlands generally included playa lakes, swamps, marshes, bogs, and similar areas such as sloughs, prairie potholes, wet meadows, prairie river overflows, mudflats, and natural ponds): Provided, That...

  13. 40 CFR 117.1 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    .... Wetlands generally included playa lakes, swamps, marshes, bogs, and similar areas such as sloughs, prairie potholes, wet meadows, prairie river overflows, mudflats, and natural ponds): Provided, That...

  14. Technical procedures for water resources, Deaf Smith County site, Texas: Volume 2: Environmental Field Program: Final draft

    SciTech Connect

    Not Available

    1987-08-01

    This volume contains the following Technical Procedures pursuant to the Water Resources Site Study Plan operation of a Playa Lake conductivity monitoring station and processing of data from a Playa Lake conductivity monitoring station. This procedure defines steps and methods for the installation, operation, and maintenance of the Playa Lake conductivity monitoring stations. Conductivity measurements will be taken at six playa lakes in the site study area to record changes in total dissolved solids as a function of stage. Playa lake conductivity and stage (volume) measurements will be used, in conjunction with other water quality data collected at the Playa Lake and precipitation stations, to determine the mass of dissolved solids entering and leaving the playas. This baseline information on the pollutant mass balance of the playas will be used to assess potential changes in playa lake water quality and the magnitude of those changes due to site development. The pollutant mass balances will also be used on determining the source of pollutants. 2 refs., 5 figs.

  15. 75 FR 75663 - Submission for OMB Review; Comment Request

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-06

    ... about the CQR Program to the highest elected officials at all levels of state, Municipio, and Tribal area government in the United States and Puerto Rico. Affected Public: State, Municipio, and...

  16. Sediments in Semi-arid Wetlands: US Southern High Plains

    USDA-ARS?s Scientific Manuscript database

    Playas are ephemeral wetlands on the semi-arid U.S. Southern High Plains that serve as runoff catchment basins and are thought to be focal points of Ogallala aquifer recharge. Sediments in playas alter biodiversity and hydroperiods. The purpose of this study was to evaluate the effects of outerbas...

  17. A Low T, High RH, and Potentially Life-Friendly Environment Within the Martian Salt-Rich Subsurface in Equatorial Regions

    NASA Astrophysics Data System (ADS)

    Wang, A.; Zheng, M. P.; Kong, F. J.; Ling, Z. C.; Kong, W. G.; Sobron, P.; Jolliff, B. L.

    2011-03-01

    Hydrated sulfates found in the subsurface at Gusev and at saline playa on the Tibet Plateau imply a high RH environment, supported by lab studies. A high-RH, salt-rich subsurface can accommodate organisms, e.g., halophiles in the Tibet saline playa.

  18. Pesticide resistance from historical agricultural chemical exposure in Thamnocephalus platyurus (Crustacea: Anostraca).

    PubMed

    Brausch, John M; Smith, Philip N

    2009-02-01

    Extensive pesticide usage in modern agriculture represents a considerable anthropogenic stressor to freshwater ecosystems throughout the United States. Acute toxicity of three of the most commonly used agricultural pesticides (Methyl Parathion 4ec, Tempo SC Ultra, Karmex DF, and DDT) was determined in two different wild-caught strains of the fairy shrimp Thamnocephalus platyurus. Fairy shrimp collected from playas surrounded by native grasslands were between 200% and 400% more sensitive than fairy shrimp derived from playas in agricultural watersheds for Methyl Parathion 4ec, Tempo SC Ultra, and Karmex DF, likely due to the development of resistance. Additionally, reduced sensitivity to DDT was observed among fairy shrimp from agriculturally-impacted playas as compared to those from native grassland-dominated playas. These data suggest that fairy shrimp inhabiting playas in agricultural regions have developed some degree of resistance to a variety of agrochemicals in response to historical usage.

  19. Redescripcion de la hembra y descripcion del macho de Pseudomethoca argyrocephala (Hymenoptera Mutillidae)

    Treesearch

    J.A. Genaro; J.A. Torres

    1999-01-01

    La especie Pseudomethoca argyrocephala fue descrita muy brevemente a partir de una hembra colectada en St. John, Islas Vfrgenes (Gerstaecker, 1874). Su presencia, inadvertida por la ausencia de ejemplares en las principales colecciones y la deposicion del holotipo en algun museo de Alemania, posiblemente motivo la omision en una clave para las especies antillanas (...

  20. 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.

  1. Sierra Nevada, California as seen from STS-59

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This view is oriented with the snow-covered mountains (Sierra Nevada of California) in the upper right corner. Then Owens Valley runs along the top of the photograph to Owens Lake playa at top center. The upper end of Death Valley extends from right to left in the foreground, with the drainage running down to a playa of Stovepipe Wells in the left foreground. Geologists are studying microwave signatures of the different playa surfaces, and the coatings on alluvial fans that extend from mountain masses, to try to sort out the history of different climates in this formerly wet but now hyperarid region.

  2. Sierra Nevada, California as seen from STS-59

    NASA Image and Video Library

    1994-04-14

    STS059-L09-162 (9-20 April 1994) --- Orient with the snow-covered mountains (Sierra Nevada of California) in the upper right corner. Then Owens Valley runs along the top of the photograph to Owens Lake playa at top center. The upper end of Death Valley extends from right to left in the foreground, with the drainage running down to a playa at Stovepipe Wells in the left foreground. Geologists are studying microwave signatures of the different playa surfaces, and the coatings on alluvial fans that extend from mountain masses, to try to sort out the history of different climates in this formerly wet but now hyperarid region.

  3. 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.

  4. 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...

  5. 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.

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Gillette, Dale A.; Adams, John; Endo, Albert; Smith, Dudley; Kihl, Rolf

    1980-10-01

    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: distrubed soils (except disturbed heavy clay soils), sand dunes, alluvial and aeolian sand deposits, disturbed playa soils, skirts of playas, playa centers, and desert pavements (alluvial deposits).

  9. 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...

  10. Thermophysical Properties of Martian Duricrust Analogs

    NASA Astrophysics Data System (ADS)

    Murphy, N. W.; Jakosky, B. M.; Mellon, M. T.; Budd, D. A.

    2009-03-01

    We measured thermophysical properties of samples of terrestrial duricrust from a gypsum deposit in New Mexico and Lunar Lake Playa. Our results suggest that well-indurated materials may cover a significant portion of the Mars surface.

  11. A Regional Guidebook for Applying the Hydrogeomorphic Approach to Assessing the Functions of Tidal Fringe Wetlands Along the Mississippi and Alabama Gulf Coast

    DTIC Science & Technology

    2007-04-01

    Hydrogeomorphic Approach vernal pools, prairie potholes in North and South Dakota, playa lakes in the high plains of Texas, kettles in New England...through evapotranspiration, intermittent or perennial outlets, or recharge to groundwater. Prairie potholes, playa lakes , vernal pools, and cypress domes...alterniflora salt marshes are a common example of tidal fringe wetlands. Lacustrine Fringe Lacustrine fringe wetlands are adjacent to lakes where

  12. 1. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    1. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 12, 1954 ELEVATION SOUTHEAST SIDE. - Castillo San Cristobal, Ravelin, Puerta de Tierra, San Juan, San Juan Municipio, PR

  13. 2. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    2. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 12, 1954 ELEVATION, SOUTHEST SIDE. - Castillo San Cristobal, Ravelin, Puerta de Tierra, San Juan, San Juan Municipio, PR

  14. Geophysical reconnaissance of Lemmon Valley, Washoe County, Nevada

    USGS Publications Warehouse

    Schaefer, Donald H.; Maurer, Douglas K.

    1981-01-01

    Rapid growth in the Lemmon Valley area, Nevada, during recent years has put increasing importance on knowledge of stored ground water for the valley. Data that would fill voids left by previous studies are depth to bedrock and depth to good-quality water beneath the two playas in the valley. Depths to bedrock calculated from a gravity survey in Lemmon Valley indicate that the western part of Lemmon Valley is considerably deeper than the eastern part. Maximum depth in the western part is about 2 ,600 feet below land surface. This depression approximately underlies the Silver Lake playa. A smaller, shallower depression with a maximum depth of about 1,500 feet below land surface exists about 2.5 miles north of the playa. The eastern area is considerably shallower. The maximum calculated depth to bedrock is about 1,000 feet below land surface, but the depth throughout most the eastern area is only about 400 feet below land surface. An electrical resistivity survey in Lemmon Valley consisting of 10 Schlumberger soundings was conducted around the playas. The maximum depth of poor-quality water (characterized by a resistivity less than 20 ohm-meters) differed considerably from place to place. Maximum depths of poor-quality water beneath the playa east of Stead varied from about 120 feet to almost 570 feet below land surface. At the Silver Lake playa, the maximum depths varied from about 40 feet in the west to 490 feet in the east. (USGS)

  15. A New Species of Culex (Melanoconion) from Southern Brazil (Diptera: Culicidae)

    DTIC Science & Technology

    1979-01-01

    and W. L. Jakob3 ABSTRACT. Cdex (Mehnoconion) Zopesi, a new species from Municipio Iguape, Estado SBo Paulo, southern Brazil is recognized. The...CostZZo do Eugenho, Municipio Iguape, in SZo Paulo state, southern Brazil in February and March, 1976. This material was found to contain specimens of

  16. Schooling for Some: Local Financial Commitment to Basic Education in Bahia, Brazil.

    ERIC Educational Resources Information Center

    Plank, David N.; Verhine, Robert E.

    1995-01-01

    Recent literature on Brazilian educational finance has documented low expenditure levels and problems of efficiency, efficacy, and equity. This paper analyzes financial data from Bahia state "municipios" and examines revenue and expenditure trends to explain variations in financial commitment across "municipios." Local interest…

  17. Traditional medicine of Baja California Sur (Mexico). I.

    PubMed

    Dimayuga, R E; Agundez, J

    1986-08-01

    This study deals with the medicinal use of 30 plants collected in the Municipio de Los Cabos and part of the Municipio de la Paz, Baja California Sur, Mexico. The plants were all taxonomically identified at least to genus level, and their medicinal use, as described to us by elder people, is discussed.

  18. 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.

  19. 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.

  20. Streamflow losses and ground-water level changes along the Big Lost River at the Idaho National Engineering Laboratory, Idaho

    SciTech Connect

    Bennett, C.M. )

    1990-01-01

    The Big Lost flows onto the eastern Snake River Plain near Arco, Idaho, and across the INEL. Stream-flow recharges the Snake River Plain aquifer from the Big Lost River channel, the INEL spreading areas, and playas at the river terminus. Average annual streamflow for the Big Lost River from 1965 to 1987 above the INEL diversion was 104,436 acre-ft; about 50% of this flow was diverted to the INEL spreading areas, about 9% infiltrated between the INEL diversion and Lincoln Boulevard, and the remainder infiltrated below Lincoln Boulevard or flowed into playas. Streamflow losses to evapotranspiration were minor compared to infiltration losses. Infiltration loss was estimated along the 44 river miles from Arco to playa 1 at discharges ranging from 37 to 372 cu ft/sec. At discharges less than 100 cu ft/sec, loss from Arco to the Big Lost River Sinks was 1 to 4 cu ft/sec/mile. Loss from the sinks to playa 1 ranged from 7 to 12 cu ft/sec/mile. Infiltration loss was greatest at large discharges. At a discharge of 372 cu ft/sec, a loss of 28 cu ft/sec/mi was estimated in the area of the Big Lost River is substantial immediately southwest of the Radioactive Waste Management Complex and in the area form the Naval Reactor Facility to playas 1 and 2.

  1. 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.

  2. 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.

  3. Hydrochemistry on the yilgarn block, western Australia: Ferrolysis and mineralisation in acidic brines

    NASA Astrophysics Data System (ADS)

    McArthur, J. M.; Turner, J. V.; Lyons, W. B.; Osborn, A. O.; Thirlwall, M. F.

    1991-05-01

    In the southeastern part of Western Australia internal drainage and a semi-arid climate have resulted in extensive development of playas. The brines beneath the playas wedge outwards and force local infiltration to crop out at playa margins as discharge zones. The discharging water contains dissolved Fe 2+, oxidation and hydrolysis (ferrolysis) of which generates very acidic water (pH ≥ 2.8). At least some of the alkalinity generated by the original reduction of Fe 3+ has been sequestered as subsurface calcrete within local soils. The acidity causes the dissolution of kaolinite, which is abundant in playa sediments and as a thick capping on weathered bedrock, giving water with a low pH and high concentrations of dissolved Al and Si. Evaporation, and mixing with playa brines containing high concentrations of K and SO 4, causes alunite to precipitate as pH rises from a minimum of 2.8, at chlorinities of 1 to 2 M, to > 6 at chlorinities of 4.8 M. The alunite deposits formed by this process are many orders of magnitude larger than occurrences elsewhere in the world. The large-scale mobilisation of Si during this process may be one mechanism for the formation of silica-cemented rocks (silcrete) that are widespread in the Australian regolith.

  4. 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

  5. Biological studies in the impact zone of the Liquefied Gaseous Fuels Spill Test Facility in Frenchman Flat, Nevada

    SciTech Connect

    Hunter, R.B.; Saethre, M.B.; Medica, P.A.; Greger, P.D.; Romney, E.M.

    1991-01-01

    Desert shrubs and rodents were monitored downwind of the Department of Energy Liquefied Gaseous Fuels Spill Test Facility (LGF), which is situated on a dry lake bed (playa). Plants were censused in 1981 and 1986 through 1990; rodent survival was measured from 1986 through 1990. During that time there were no apparent effects of the spill tests on animals or plants off the edge of the playa, which extends more than 2.5 kilometers from the facility. Plant populations increased in volume from 1981 through 1986, then declined precipitously during drought in 1989 and 1990. Rodent populations also declined during the drought. Some effects of spilled hydrogen fluoride gas were seen on plants growing on manmade mounds on the playa surface. Animal and bird species seen in the vicinity of the LGF are also reported. 11 refs., 10 figs., 16 tabs.

  6. Preliminary results on quaternary studies from Bajestan Basin (Kavir-e Namak), Iran

    NASA Astrophysics Data System (ADS)

    Majid Padashi, Seyed; Büdel, Christian; Ullmann, Tobias; Tintrup, Angela; Baumhauer, Roland

    2017-04-01

    The increasing population and demand for developing infrastructures on the one hand, and the recent issues on water and air quality on the other hand, in addition to droughts and the shrinking of many wetlands and lakes, have encouraged Iran recently to invest more in palaeoenvironmental research - specifically on quaternary basins. Preliminary results of our study through field work, satellite imagery processing, SRTM data analysis and drilling, have created new insights on the Iranian playas and the history of the lakes. A combined geological and geomorphological approach for studying young lakes and playas of Iran has led to the identification of at least five major types of lakes and playas in different parts of Iran; for example the Bajestan basin which ranks the second biggest playa of Iran, is placed in the edge of the central Iranian microplate and Lut structural block. The Bajestan Playa (Kavir-e Namak) is surrounded by cretaceous limestones in the south and Paleozoic formations in the north. The basin comprises several kinds of quaternary deposits including sand dunes and Aeolian deposits, fluvial sediments, alluvial fans and lake sediments. The aeolian activity in the basin is primarily shaping landforms in the southwest and the north of the area. The major fluvial activity is considered to be driven from east and south of the playa. The integration of field observations and data derived from the analysis of SRTM digital elevation model (90m) and Landsat satellite imagery shows that the major part of the playa has flat slope. In addition, the morphometric assessment and the hydrological modelling showed that the major current alluvial channels have SW/NE trend with the highest density and intensity of activity in south west of the basin. The major alluvial deposits in the north and south of the playa represent a dissimilar geomorphology. While the northern part of the basin, from the rock unit outcrops to the edge of playa, is occupied by a narrow

  7. Ferris Wheel Series Air Vent/Flat Top Events

    DTIC Science & Technology

    1968-09-27

    displacements and horizoe.Wi components of vel.city by direct ground shock. Flat Top I in limestone was ’sub- seismic through most of the range of measurement...cube root. Area 5 playa yielded smaller craters than Area 10 alluvium . Soil moisture was an important factor; Flat Top III, fired in the same soil 60...Results of Surface-Burst Scaling ----------------------- 89 4.5.2 Playa- Alluvium Comparison 90 - 4.5.3 Results, Flat Tops U and III 92 4.5.4 Results

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 8. General view looking S at archeological excavations along base ...

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

    8. General view looking S at archeological excavations along base of west wall of purging house. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  18. 16. View looking E at foundation ruins of steam engine ...

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

    16. View looking E at foundation ruins of 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

  19. 15. View looking N at foundation ruins of steam engine ...

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

    15. View looking N at foundation ruins of 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

  20. 18. View of Lancashire double tube boiler salvaged from another ...

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

    18. View of Lancashire double tube boiler salvaged from another site. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  1. 11. View looking from opposite direction (N) at arched opening ...

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

    11. View looking from opposite direction (N) at arched opening depicted in previous view. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  2. 19. View looking N at mill wall ruins with open ...

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

    19. View looking N at mill wall ruins with open end of purging house in background. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  3. 18. View of archeological excavations along base of mill wall ...

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

    18. View of archeological excavations along base of mill wall showing unidentified pits. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  4. 16. View of cane mill sitting under open shed showing ...

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

    16. View of cane mill sitting under open shed showing discharge and top rolls. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  5. 21. View of interior of purging house looking N showing ...

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

    21. View of interior of purging house looking N showing roof trussing. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  6. 25. View of chimney with mill wall ruins in background ...

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

    25. View of chimney with mill wall ruins in background looking S. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  7. 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

  8. 6. INTERIOR, FORMER QUARTERS OF THE SPANISH NAVY, LARGE ROOM ...

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

    6. INTERIOR, FORMER QUARTERS OF THE SPANISH NAVY, LARGE ROOM WING TO WEST OF ENTRANCE PORTICO SHOWING BEAMED CEILING CONSTRUCTION. - El Arsenal, Former Headquarters of the Spanish Navy, Calle Arsenal, San Juan, San Juan Municipio, PR

  9. 1. FORMER QUARTERS OF THE SPANISH NAVY, WEST ELEVATION OF ...

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

    1. FORMER QUARTERS OF THE SPANISH NAVY, WEST ELEVATION OF TWO STORY WING TO EAST OF PRINCIPAL COURTYARD. - El Arsenal, Former Headquarters of the Spanish Navy, Calle Arsenal, San Juan, San Juan Municipio, PR

  10. 7. INTERIOR, FORMER QUARTERS OF THE SPANISH NAVY, DETAIL OF ...

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

    7. INTERIOR, FORMER QUARTERS OF THE SPANISH NAVY, DETAIL OF THE UNDERSIDE OF BEAM AND BATTEN CEILING, WING TO WEST OF ENTRANCE PORTICO. - El Arsenal, Former Headquarters of the Spanish Navy, Calle Arsenal, San Juan, San Juan Municipio, PR

  11. 2. FORMER QUARTERS OF THE SPANISH NAVY, BRICK WALL CONSTRUCTION ...

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

    2. FORMER QUARTERS OF THE SPANISH NAVY, BRICK WALL CONSTRUCTION DETAIL SHOWING ARCHES OF SOUTH WALL OF WEST WING OF ENTRANCE PORTICO. - El Arsenal, Former Headquarters of the Spanish Navy, Calle Arsenal, San Juan, San Juan Municipio, PR

  12. 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

  13. 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

  14. 13. Detail view of arched opening where fuel was fed ...

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

    13. Detail view of arched opening where fuel was fed to fire Jamaican Train. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  15. 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

  16. 9. View looking S at archeological excavations at base of ...

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

    9. View looking S at archeological excavations at base of wall adjacent to Jamaican Train. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  17. 22. Detail view of castiron kettles used in Jamaican Train ...

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

    22. Detail view of cast-iron kettles used in Jamaican Train with standing man for scale. - Hacienda Azucarera La Concepcion, Sugar Mill Ruins, .3 Mi. W. of Junction of Rts. 418 & 111, Victoria, Agaudilla Municipio, PR

  18. 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

  19. 13. Aqueduct tablet with Benjamin NistalMoret (Project Historian) and Mrs. ...

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

    13. Aqueduct tablet with Benjamin Nistal-Moret (Project Historian) and Mrs. Charles Egbert (wife of Supervisory Architect) in picture. - Hacienda Buena Vista, PR Route 10 (Ponce to Arecibo), Magueyes, Ponce Municipio, PR

  20. 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

  1. 3. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    3. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 DETAIL OF GATE, WEST ELEVATION. - Fortin de San Jeronimo de Boqueron, Puerta de Tierra, San Juan, San Juan Municipio, PR

  2. 6. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    6. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 DETAIL OF ENTRANCE, EAST ELEVATION. - Fortin de San Juan de la Cruz, El Canuelo, Isla de Cabras, San Juan, San Juan Municipio, PR

  3. 5. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    5. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 DETAIL OF SENTRY BOX AND EMBRASURES, NORTHEAST CORNER. - Fortin de San Juan de la Cruz, El Canuelo, Isla de Cabras, San Juan, San Juan Municipio, PR

  4. 9. Historic American Buildings Survey, January, 1935 WEST AND SOUTH ...

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

    9. Historic American Buildings Survey, January, 1935 WEST AND SOUTH ELEVATIONS BEFORE EL CANUELO WAS CONNECTED WITH CABRAS ISLAND. - Fortin de San Juan de la Cruz, El Canuelo, Isla de Cabras, San Juan, San Juan Municipio, PR

  5. 3. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    3. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 DETAIL OF SENTRY BOX CORDON AND MASONRY, NE CORNER. - Fortin de San Juan de la Cruz, El Canuelo, Isla de Cabras, San Juan, San Juan Municipio, PR

  6. 7. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    7. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 WEST AND SOUTH ELEVATIONS. - Fortin de San Juan de la Cruz, El Canuelo, Isla de Cabras, San Juan, San Juan Municipio, PR

  7. 1. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    1. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 ENTRANCE, WEST ELEVATION. - Fortin de San Jeronimo de Boqueron, Puerta de Tierra, San Juan, San Juan Municipio, PR

  8. 8. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    8. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 STAIRCASE FROM FIRST LEVEL TO GUN DECK. - Fortin de San Juan de la Cruz, El Canuelo, Isla de Cabras, San Juan, San Juan Municipio, PR

  9. 4. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    4. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 DETAIL OF KITCHEN AND LATRINE SOUTHWEST CORNER. - Fortin de San Juan de la Cruz, El Canuelo, Isla de Cabras, San Juan, San Juan Municipio, PR

  10. 2. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    2. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 BRIDGE, WEST ARCH, SOUTH ELEVATION. - Fortin de San Jeronimo de Boqueron, Puerta de Tierra, San Juan, San Juan Municipio, PR

  11. 1. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    1. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 EAST AND NORTH ELEVATIONS. - Fortin de San Juan de la Cruz, El Canuelo, Isla de Cabras, San Juan, San Juan Municipio, PR

  12. 1. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    1. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 EAST ELEVATION. - Fortifications of San Juan, Outer Defenses, Puerta de Tierra, San Juan, San Juan Municipio, PR

  13. 2. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    2. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 WEST ELEVATION. - Fortifications of San Juan, Outer Defenses, Puerta de Tierra, San Juan, San Juan Municipio, PR

  14. 3. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    3. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 WALL FRAGMENTS AT NORTH END OF SECOND LINE OF DEFENSE, NORTH ELEVATION. - Fortifications of San Juan, Outer Defenses, Puerta de Tierra, San Juan, San Juan Municipio, PR

  15. 7. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    7. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 SAN ANTONIO BATTERY AND APPROACH, NORTH ELEVATION. - Fortifications of San Juan, Outer Defenses, Puerta de Tierra, San Juan, San Juan Municipio, PR

  16. 8. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    8. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 SAN ANTONIO BATTERY, EAST ELEVATION. - Fortifications of San Juan, Outer Defenses, Puerta de Tierra, San Juan, San Juan Municipio, PR

  17. 6. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    6. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 GATE POST AND WALL FRAGMENT OF FIRST LINE OF DEFENSE, SOUTH ELEVATION. - Fortifications of San Juan, Outer Defenses, Puerta de Tierra, San Juan, San Juan Municipio, PR

  18. 4. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    4. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 WALL FRAGMENT AT NORTH END OF SECOND LINE OF DEFENSE, EAST ELEVATION. - Fortifications of San Juan, Outer Defenses, Puerta de Tierra, San Juan, San Juan Municipio, PR

  19. 5. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April ...

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

    5. Historic American Buildings Survey, Frederik C. Gjessing, Photographer April 19, 1954 SENTRY BOX AND WALL FRAGMENT OF FIRST LINE OF DEFENSE, NORTH ELEVATION. - Fortifications of San Juan, Outer Defenses, Puerta de Tierra, San Juan, San Juan Municipio, PR

  20. Interior view of living and dining areas, showing their separation ...

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

    Interior view of living and dining areas, showing their separation by medio punto, view towards the north, northeast - Pou Coffee Processing Structure, Casa No. 2, Highway 139, Kilometer 12, Maraguez, Ponce Municipio, PR

  1. 16. REPRODUCTION OF ARMY PHOTOGRAPH, AERIAL VIEW, LOOKING WEST, SHOWING ...

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

    16. REPRODUCTION OF ARMY PHOTOGRAPH, AERIAL VIEW, LOOKING WEST, SHOWING WESTERN END OF FORT (OFFICERS QUARTERS, TROOPS QUARTERS, SAN CHRISTOBAL). PHOTOGRAPHER AND DATE UNKNOWN. - Castillo de San Christobal, Boulevard Norzagaray, San Juan, San Juan Municipio, PR

  2. 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

  3. 6. General view showing most of west elevation and main ...

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

    6. General view showing most of west elevation and main entrance (southern end of elevation is obstructed) - Giorgetti, Eduardo, House, Ponce de Leon Avenue, Santurce, San Juan, San Juan Municipio, PR

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 22. Detail view of arched passageway as in preceeding photo. ...

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

    22. Detail view of arched passageway as in preceeding photo. - 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. 16. View of middle bay of N (rear) elevation looking ...

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

    16. View of middle bay of N (rear) elevation looking SE. - 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

  17. 29. Detail view of small triangular openings from opposite side ...

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

    29. Detail view of small triangular openings from opposite side of wall. - 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

  18. 3. View of Santa Elena, looking from water level (Note: ...

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

    3. View of Santa Elena, looking from water level (Note: The lighthouse of Del Morro is just visible in the background) - Murallas del Viejo San Juan, Baluarte de Santa Elena, San Juan, San Juan Municipio, PR

  19. 2. Skewed view of E elevation of sugar mill looking ...

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

    2. Skewed view of E elevation of sugar mill looking NW. - 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

  20. 23. Detail view of brickwork in same arched passageway. ...

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

    23. Detail view of brickwork in same arched passageway. - 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

  1. Exterior view of southern half of east porch, showing entrance ...

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

    Exterior view of southern half of east porch, showing entrance to second story of la casa, view towards the west - Pou Coffee Processing Structure, Casa No. 2, Highway 139, Kilometer 12, Maraguez, Ponce Municipio, PR

  2. View of corredera supports and rear (southwest) of house, including ...

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

    View of corredera supports and rear (southwest) of house, including attachment of rails to la casa, view towards the east - Finca Thillett, Casa, Highway 139, Kilometer 11.6, Maraguez, Ponce Municipio, PR

  3. Exterior 3/4 view of north and west sides of la ...

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

    Exterior 3/4 view of north and west sides of la casa, showing entrance to first story, view towards the south. - Pou Coffee Processing Structure, Casa No. 2, Highway 139, Kilometer 12, Maraguez, Ponce Municipio, PR

  4. Interior view of wooden despulpadora converted for use with electric ...

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

    Interior view of wooden despulpadora converted for use with electric motor in lower level of casa No. 1, view towards the southwest - Pou Coffee Processing Structure, Casa No. 1, Highway 139, Kilometer 12, Maraguez, Ponce Municipio, PR

  5. 3. Photocopy of photograph, original photographer unknown, ca. 1921; VIEW ...

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

    3. Photocopy of photograph, original photographer unknown, ca. 1921; VIEW LOOKING SOUTHWEST, APPARENTLY AFTER A HURRICANE (NOTE ROOF DAMAGE) - Superintendent of Lighthouses Dwelling, Punta Puntilla, San Juan, San Juan Municipio, PR

  6. 2. Photocopy of photograph, original photographer unknown, ca. 1921; VIEW ...

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

    2. Photocopy of photograph, original photographer unknown, ca. 1921; VIEW LOOKING NORTHWEST, APPARENTLY AFTER A HURRICANE (NOTE ROOF DAMAGE) - Superintendent of Lighthouses Dwelling, Punta Puntilla, San Juan, San Juan Municipio, PR

  7. 1. Photocopy of book illustration, undated ca. 1898; LIGHTHOUSE CONSTRUCTED ...

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

    1. Photocopy of book illustration, undated ca. 1898; LIGHTHOUSE CONSTRUCTED CA. 1876, DESTROYED 1898 - Castillo de San Felipe del Morro Lighthouse, Summit of Castillo de San Felipe del Morro, San Juan Antiguo (subdivision), San Juan Municipio, PR

  8. 10. Detail view of flywheel and single reduction gear with ...

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

    10. Detail view of flywheel and single reduction gear with Benjamin Nistal-Moret (Project Historian) in foreground. - Hacienda Azucarera la Igualdad, Sugar Mill Ruins & Steam Engine, PR Route 332, Guanica, Guanica Municipio, PR

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

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

    5. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, 1956 DETAIL, CHAPEL ELEVATION, 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. 7. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, ...

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

    7. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, 1956 ALTAR, CHAPEL 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

  11. 3. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, ...

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

    3. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, 1956 ELEVATION OF CHAPEL, 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

  12. [The process of metropolizing Monterrey: there must be a long-term plan].

    PubMed

    Garza, G

    1994-01-01

    Monterrey achieved metropolitan status in the 1950s, when it expanded toward the municipios of Guadalupe and San Nicolas de los Garza. 93.6% of the total metropolitan population at that time lived in the municipio of Monterrey. Between 1950 and 1960 metropolitan Monterrey grew at an annual rate of 6.7% and the population nearly doubled. In the 1960s three other municipios were added to the metropolitan area, for a total of seven, and the share of the population living in the municipio of Monterrey dropped to 68.3%. From 1970 to 1980, metropolitan Monterrey's annual growth rate declined to 4.6%, and only one municipio was added. The municipio of Monterrey had a growth rate of 2.2%, while the surrounding municipios had rates several times higher. The process of metropolitanization decelerated considerably between 1980 and 1990, with an annual growth rate of 2.5% for the metropolitan region, the lowest since 1910-21. The municipio of Monterrey had a negative growth of -0.2% in the 1980s. Industrialization was the main determinant of metropolitan growth in Monterrey. Industrial growth was most rapid between 1950 and 1970, when 10.4% of national industry was located in Monterrey. Monterrey was seriously affected by the economic crisis of the 1980s, suffering a decline of 1.1% annually and a reduction of its share of national industry to 8.8% by 1988. If the economic recuperation of 1988-92 continues, Monterrey is projected to increase by 75% in population and 60% in urban area in the next 20 years, implying the need for tremendous infrastructural construction. Longterm planning must be carried out to minimize the problems of growth and size in Monterrey and to assure an adequate economic foundation for the metropolis.

  13. Traditional medicine of Baja California Sur (Mexico). II.

    PubMed

    Encarnacion Dimayuga, R; Fort Murillo, R; Luis Pantoja, M

    1987-08-01

    Continuing our studies of traditional medicine, as used in rural areas of Baja California Sur, now we wish to report on the medicinal uses of 49 more plants. Some of the more complex recipes of these medicinal plants, are discussed in the present paper. The information presented here was collected in the Municipio of Los Cabos and part of the Municipio of La Paz, B.C.S., Mexico.

  14. Socioeconomic Incentives for Migration from Mexico to the United States: Magnitude, Recent Changes, and Policy Implications.

    DTIC Science & Technology

    1980-07-01

    32 states or the 89 minimum-wage regions. The next set of small regions would carry the analysis to the level of municipios , county-like geographical...units. But there are more than 2650 municipios in Mexico. To work with only the 32 states would have implied far greater homoneneity within regions...Nogales 35. San Luis Potosi Norte 65. Puebla Sier!:a 6. Chihuahua Cd. Juarez 36. San Luis Potosi Sur 66. Puebla Area Metro. 7. Chihuahua Sierra 37

  15. 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…

  16. 40 CFR 117.1 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .... Wetlands generally included playa lakes, swamps, marshes, bogs, and similar areas such as sloughs, prairie... the ebb and flow of the tide; (2) Interstate waters, including interstate wetlands; (3) All other..., and wetlands, the use, degradation or destruction of which would affect or could affect interstate...

  17. 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.

  18. 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.

  19. Tropical Cyclones within the Sedimentary Record: Analyzing Overwash Deposition from Event to Millennial Timescales

    DTIC Science & Technology

    2009-02-01

    Reconstructing relative flooding intensities responsible for hurricane- Induced deposits from Laguna Playa Grande, Vieques, Puerto Rico…..17 Chapter 4...and Donnelly, 2007; van de Plassche et al., 2004). To date there are relatively few sedimentary reconstructions of tropical cyclone activity which...consideration when assessing the significance of trends observed within these paleo-storm reconstructions . Given the importance of identifying the

  20. 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…

  1. Chapter 2. Borderlands environment, past and present

    Treesearch

    Guadalupe Sanchez de Carpenter; A.C. MacWilliams

    2006-01-01

    The major mountain ranges in the study area today were produced by Middle Miocene and younger extensional faulting. Faulting continued into the late Pleistocene as evidenced by fault scarps along the margins of the Animas, Hachita, and Playas Valleys. These long-term geologic events resulted in the present basin and range physiography of the Malpai Borderlands, as...

  2. 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...

  3. 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.

  4. 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…

  5. 76 FR 34211 - Intent To Prepare a Draft Environmental Impact Statement for the Proposed Kennecott Utah Copper...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-13

    ... waters of the United States, including wetlands, to construct the project. The basic project purpose is... United States (waters), including wetlands, have been identified on the proposed project site. The area of impacted wetlands includes 488 acres of vegetated saline playa and 76.9 acres of emergent...

  6. 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...

  7. Prescribed Fire in Industrial Pine Plantations

    Treesearch

    C. de Ronde; J. G. Goldammer; D. D. Wade; R. V. Soares

    1990-01-01

    Industrial plantations of non-indigenous tree species (exotics) can be defined as even-aged stands established outside of their natural habitat. These plantations playa vital economic role in the developing countries of the tropics and subtropics. The ecological benefits of afforestation, however, go farbeyond local and regional considerations: the increase...

  8. 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…

  9. Resource Islands Predict the Distribution of Heterotrophic Bacteria in Chihuahuan Desert Soils

    PubMed Central

    Herman, R. P.; Provencio, K. R.; Herrera-Matos, J.; Torrez, R. J.

    1995-01-01

    The resource island hypothesis predicts that soil resources such as nitrogen, phosphorus, and water will be distributed evenly in grasslands but have a patchy distribution focused around plants in shrublands. This hypothesis predicts that microorganism numbers will follow resources and be (i) evenly distributed in grasslands, (ii) concentrated around individual plants in shrublands, and (iii) higher where resources are higher when comparing the same vegetation type. This study enumerated total heterotrophic bacteria and a subset of these, the nitrogen-efficient guild (NEG), in three shrublands (playa fringe mesquite, tar bush, and creosote) and two grasslands (playa and bajada). Both heterotrophs and NEG members followed the distribution pattern predicted by the resource island hypothesis. There were no significant differences in heterotroph or NEG numbers comparing at-plant and interplant samples for both the playa and bajada grasslands. Furthermore, populations were generally higher in nutrient-rich playa grasslands than nutrient-poor bajada grasslands. In contrast, both heterotroph and NEG numbers were higher at shrubs than between shrubs in all three shrub sites. These results suggest that resource abundance in resource islands predicts the distribution of heterotrophic bacterial numbers in desert soils. PMID:16535022

  10. 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…

  11. 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...

  12. Archaeological Investigations of Three Sites within the Wipp Core Area, Eddy County, New Mexico.

    DTIC Science & Technology

    1985-06-01

    soils occasionally contain small playas, which hold water, generally quite saline , for short periods of time. Soils of this association are used for...be substituted for rhubarb (Castetter 1935:50). Portulacaceae Po 1*Maca. gZr Small purslane .E. Le Retose purslane Portulaca is a very important

  13. 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...

  14. Chapter 3. Malpai Borderlands prehistory

    Treesearch

    Paul R. Fish; Suzanne K. Fish

    2006-01-01

    Systematic archaeology in the Malpai Borderlands begins with D. D. Gaillard's (1896) map of the elevated Cloverdale Playa beachline in the San Luis Valley. During his involvement with the U.S.-Mexico International Border Survey, Gailard was drawn to this feature by local ranchers' reports of a massive Native American dam. Familiar with the scale of...

  15. The role of landscape anomalies in regional plant conservation

    Treesearch

    S. Kelso; C. Hall; G. Maentz

    2001-01-01

    Landscape anomalies are regionally restricted habitats created by unusual geologic, edaphic, or hydrologic factors. Barrens, cliff faces, canyons, hanging gardens, and playas are all examples of landscape anomalies in the arid Southwest. Such sites often harbor an unusual and rich flora, including endemic, disjunct, or relictual plant species. Using examples from our...

  16. 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…

  17. Microbes in Evaporite Salts on Tibet Plateau as Analog for Martian Life in Salt Environments

    NASA Astrophysics Data System (ADS)

    Kong, F. J.; Zheng, M. P.; Wang, A.; Ma, N. N.; Amend, J.

    2010-04-01

    Da Langtan playa occurs at the west end of Qaidam Basin, on northern part of Tibet plateau. The characterization of halophiles isolated from the evaporative salts in the area, and SEM and EDAX for microbial biosignatures in the evaporate crystal sample was report.

  18. Endolithic Halophiles Found in Evaporite Salts on Tibet Plateau as a Potential Analog for Martian Life in Saline Environment

    NASA Astrophysics Data System (ADS)

    Kong, F. J.; Zheng, M. P.; Wang, A. L.; Ma, N. N.

    2009-03-01

    Mg-sulfates was found within salt deposits of the Da Langtan playa on Tibet plateau, similar as those found on Mars. Halophiles were isolated from the evaporative salts in the environment for analogs of the search for martian life in subsurface.

  19. A framework of field observations and spatial data for understanding dust emissions in the Mojave Desert

    NASA Astrophysics Data System (ADS)

    Ballantine, J.; Reynolds, R. L.; Chavez, P.; Bogle, R.; Clow, G.; Fulton, R.; Reheis, M.; Urban, F.; Wallace, C.; Yount, J.

    2007-12-01

    Modeling dust events at landscape to regional scales requires field observations of dust-source characteristics, mapping of source types by remote sensing, and wind fields representing the conditions that mobilize dust from the surface. A conceptual framework has been built for understanding dust-source types and their dynamics in the Mojave Desert. Observations of dust events in the Mojave indicate five general source types: 1) Sparsely vegetated surfaces that are vulnerable during periods of drought; 2) wet playas where a near-surface groundwater table generates "fluffy" (very soft sediment) conditions; 3) transitional playas where groundwater extraction has lowered the water table, and playa surface composition produces sediments that are vulnerable to erosion; 4) ephemeral flood deposits; and 5) anthropogenic sources where off-road vehicles, military training exercises, and dirt roads create a disturbed surface. Some sources are perennial and others are strongly influenced (sometimes in opposite ways) by precipitation cycles. A multi-year study of precipitation, vegetation, winds, and saltation at several plots in the Mojave National Preserve shows that blooms of annual vegetation in wet years can leave biomass that protects the surface for more than a year after the rains. Monitoring of the wet Franklin Lake Playa shows that a shallow ground-water table is associated with more vulnerable conditions for dust emission. Repeat photography of the relations between winds and dustiness at transitional Mesquite Lake Playa shows that dust is mobilized during the spring when winds are greater than about 5 m/s. Satellite images reveal dust emission from ephemeral fluvial systems, such as the Mojave River Sink, at the end of wet spring seasons. Satellite images also document dust emissions from areas of heavy military and off-road vehicle activity. Landsat imagery was used to map perennial vegetation cover for the Mojave Desert, calibrated to 250 field transects. The

  20. [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.

  1. In-flight calibration of the spectral and radiometric characteristics of AVIRIS in 1991

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Conel, James E.; Bruegge, Carol J.; Margolis, Jack S.; Carrere, Veronique; Vane, Gregg; Hoover, Gordon

    1992-01-01

    On 7 Mar. 1991, an in-flight calibration experiment was held at the Ivanpah Playa in southeastern California for the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) imaging spectrometer. Five AVIRIS overflights were acquired of a calibration target designated on the Ivanpah Playa surface. At the time of the overflights, the reflectance of the calibration target was measured with a field spectrometer. In addition, the atmospheric optical depths and water vapor abundance were measured from a radiometer station adjacent to the calibration target. These in-situ measurements were used to constrain the MODTRAN radiative transfer code to model the upwelling spectral radiance incident to the sensor aperture during the overflights. Analyses of this modeled radiance in conjunction with the laboratory-calibrated radiance were used to determine the spectral and radiometric calibration of AVIRIS while in flight.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Identification of the First Receptor for a Pregnancy Specific Glycoprotein. Tetraspanins Find Their Ligand

    DTIC Science & Technology

    2001-04-13

    zed animal system. Both human and mice are hemochorial placentation mammals: maternal blood does not come into direct contact with fetal blood duc to ...by maternal immune ce ll s [85]. Several mechanisms thought to playa role in the regu lation of " fetal immune privilege" arc rev iewed here. All...maintenance and poss ibly invasion but is repressed prior to parturition [130]. Co-culturing of nonnal maternal PBMC with placental an ti gens has

  7. Environmental Impact Statement. Preliminary Draft. Realignment of Cannon Air Force Base, Curry County, New Mexico

    DTIC Science & Technology

    1989-12-15

    diversity. Most amphibian species are associated with riparian habitats and playa lakes. Reptiles are found in all terrestrial habitat types but are...at a 40-site campground. Fishing is permitted from May to September, and no hunting is allowed. There is a 1/2-mile trail to dinosaur tracks. The...girardi Recent occurrence unlikely Speckled chub Hybol aestivalis Recent occurrence unlikely I Reptiles Western ribbon snake Thamnophis proximus Less than

  8. 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.

  9. 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.

  10. M-X Environmental Technical Report. Environmental Characteristics of Alternative Designated Deployment Areas, Mining and Geology.

    DTIC Science & Technology

    1980-12-22

    dollar value plus court time represented. A rounded figure of $49 million for real estate acquisition in the Great Basin (Nevada and Utah) area has...distribution on minerals industry activity in Nevada. 15 3.3.1-1 Distribution of patented and unpatented mining claims. 49 4.2.2-1 Earthquake...to 15 percent with the steeper slopes closer to the mountains. The valley floors most frequently have slopes between I and 5 percent while the playas

  11. Predator Force Structure Changes at Indian Springs Air Force Auxiliary Field, Nevada Environmental Assessment

    DTIC Science & Technology

    2003-07-01

    schidigera ). At higher elevations (~4,000 feet), Joshua tree ( Yucca brevifolia) becomes prevalent. On valley bottoms and dry lake beds (playas) at...vicinity are considered inactive. The only known active fault in the area is the Yucca fault, located approximately 20 miles northwest at the southern...border of North Range. The Yucca fault is considered active based on displacement of Holocene and Pleistocene alluvium by as much as 60 feet. Offsets

  12. [First report of Triatoma nigromaculata (Stål, 1859) (Hemiptera, Reduviidae, Triatominae) for Colombia].

    PubMed

    Vásquez, Luis Reinel; Galvão, Cleber; Pinto, Néstor A; Granados, Humberto

    2005-09-01

    The presence of Triatoma nigromaculata was recorded for the first time in Colombia in the rural village La Playa in the province of Cauca. A single female was captured from an outdoor area near a household. The presence of Trypanosoma parasites in the specimen was not established due to the poor condition of the specimen. The epidemiological importance of this finding is discussed with respect to the potential for transmission of Chagas disease in the province of Cauca and, more broadly, in Colombia.

  13. Calibration Targets of the Southwest: Albedo and Homogeneity Comparisons Using AVIRIS Data

    NASA Technical Reports Server (NTRS)

    Pavri, Betina; Green, Robert

    1998-01-01

    Various locations in the southwestern U.S. are used to calibrate remote sensing instruments. This study shows how some of these targets compare in terms of albedo and homogeneity, and records the variation of these factors for a single location (Ivanpah Playa) over a period of one year. Results indicate that there is a great deal of variation among these targets in albedo, spectral flatness, and surface uniformity, and that these factors can change throughout the year.

  14. Engineering and Environmental Geology of the Indian Wells Valley Area.

    DTIC Science & Technology

    1987-11-06

    Lake playa. The local hydrologic system is composed of two ground-water bodies (Reference 45): a shallow aquifer perched on lacustrine clays near and...6404, publication UNCLASSIFIED.) 42. U.S. Geological Survey. Geologic and Hydrologic Features of Indian Wells Valley, California, by L. C. Dutcher and W...R. Moyle, Jr., Water Supply Paper 2007, 1973, 30 pp. 36 SA NWC TP 6854 43. Leedshill-Herkenhoff, Inc. Alternative Measures to Lower the Groundwater

  15. Effect of Arctic Amplification on Design Snow Loads in Alaska

    DTIC Science & Technology

    2016-09-01

    8 Playa shrubland 1 — 9 Shrub wetland /riparian 1.75 — 10 Erect shrub tundra 0.65 — 11 Low shrub tundra 0.3 — 12 Grassland rangeland 0.15 — 13...Subalpine meadow 0.25 — 14 Tundra (non-tussock) 0.15 — 15 Tundra (tussock) 0.2 — 16 Prostrate shrub tundra 0.1 — 17 Arctic gram, wetland 0.2 — 18

  16. Final Environmental Assessment for Effluent Irrigation of the Golf Course Holloman Air Force Base Otero County, New Mexico

    DTIC Science & Technology

    2008-10-01

    managers for several reasons. First, neotropical migratory birds play a major role in the health and functioning of ecosystems, as consumers of insects ...shallow standing \\Vater rnay ren1ain for several weeks after heavy rains. Playas may contain a higher 22 Final Environmental Assessment for Golf...bacterial growth that support a substantial insect community that in tum attracts considerable numbers of wetland birds to the area throughout the

  17. Revolution in the Philippines: Comparing the Communist and Muslim Insurgencies

    DTIC Science & Technology

    2007-11-02

    Maria Sison, and his military chief, Commander Dante, were arrested by the Ferdinand Marcos regime for terrorist actions committed against the...funds to support their cause.28 Later, the CPP and NPA carried on the legacy. One of the contributing factors to Ferdinand Marcos ’ declaration of...martial law in 1971 was the NPA’s connection with the Playa Miranda bombing that took place in August of that same year.29 Years after the bombing, NPA

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Differences in Soil Moisture Dynamics across Landforms in South Texas Shrublands

    NASA Astrophysics Data System (ADS)

    Basant, S.; Wilcox, B. P.

    2016-12-01

    To understand the water budget for a landscape, it is important to understand the hydrologic differences between different landforms constituting the landscape. The Tamaulipas Biotic Province shrublands in South Texas are characterized by primarily three different landforms - the sandy loam uplands, clay loam intermittent drainage woodlands and closed basin depressions situated in intermittent drainage ways, also referred to as `playas'. Texas A&M's La Copita Research Area (LCRA) in South Texas is a similar landscape where previous research has been limited to soil water movement in uplands and localized water accumulation in the playa landforms. The objective of this research is to understand the hydrology of different landforms and integrate them to complete a landscape scale water budget. Deep soil water movement will be measured at LCRA using neutron moisture gauges. Over 50 access tubes distributed around the site will be used to cover the dominant landforms and vegetation classes. Soil moisture will be measured up to a depth of 2m at different times of the year - so as to capture the variability in response to different rain events and also to different seasons. This will be complimented by over 6 years of run off data collected from controlled plots which will provide an estimate on the amount of overland water exchange from uplands to drainage and playas. The depth-wise soil moisture data collected over time will also be used to estimate the variability in plant water uptake rates across different sites.

  3. 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.

  4. Earth Obsersation taken by the Expedition 11 crew

    NASA Image and Video Library

    2005-06-27

    ISS011-E-09680 (27 June 2005) --- Searles Lake, California is featured in this image photographed by an Expedition 11 crewmember on the International Space Station. Searles Lake is known for the abundance of rare elements and evaporite minerals, such as trona, hanksite, and halite formed within its sediments. These minerals dissolve in water or very humid environments. According to NASA scientists who are studying the Space Station photography, during the Pleistocene Epoch (beginning approximately two million years ago), Searles Lake was one of a chain of lakes fed by streamflow from the Sierra Nevada to the west. Lake levels rose and fell dependant on glacial outwash from the Sierra Nevada as climates shifted. Successive layers of sediment were deposited as lake levels fluctuated, preserving an important record of regional climate change. The lakes gradually dried up completely as climatic conditions became hotter and drier (as today), forming a string of enclosed basins with no outlets (playas). This photograph depicts the Searles Lake playa (characterized by white surface mineral deposits) bounded by the Argus and Slate Mountains. The width of the playa is approximately 10 kilometers. The center of the image is dominated by mining operations that extract sodium- and potassium-rich minerals (primarily borax and salt) for industrial use. Minerals are primarily in naturally-occurring brines that are pumped to the surface and evaporated to crystallize the minerals. A large evaporation pond (black) is visible in the center of the image. Further processing concentrates the minerals and removes excess water.

  5. Comparison of bacterial biodiversity and enzyme production in three hypersaline lakes; urmia, howz-soltan and aran-bidgol.

    PubMed

    Babavalian, Hamid; Amoozegar, Mohammad Ali; Zahraei, Shirin; Rohban, Rokhsareh; Shakeri, Fatemeh; Moghaddam, Mehrdad Moosazadeh

    2014-12-01

    This research is a comparative study on the diversity of halophilic bacteria with hydrolytic activities in three significant hypersaline lakes; Urmia in the northwest and Howz-Soltan and Aran-Bidgol in the central desert in Iran. Isolated strains from these saline lakes were found to be halotolerant, moderately and extremely halophilic bacteria. The bacteria in each saline lake were able to produce different hydrolytic enzymes including amylase, protease, lipase, DNase, inulinase, xylanase, carboxy methyl cellulase, pectinase and pullulanase. 188, 302, 91 halophilic strains were isolated from Urmia Lake, Howz-Soltan and Aran-Bidgol playa, respectively. The numbers of Gram-positive strains were more than Gram-negatives, and among Gram-positive bacteria; spore-forming bacilli were most abundant. Due to the unique physico-chemical conditions of the lake environments, the hydrolytic activities of isolated strains were significantly different. For instance, isolated strains from Howz-Soltan playa did not produce pectinase, DNase, amylase, lipase and inulinase, while the isolates from Aran-Bidgol playa had a great ability to produce pectinase and DNase. The strains from Urmia Lake were also good producers of DNase but failed to show any chitinase activity. The diversity of halophilic bacteria from the mentioned three saline lakes was also determined using PCR-amplified 16S rRNA followed by phylogenetic analysis of the partial 16S rRNA sequences.

  6. 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.

  7. Quantifying dust emissions from desert landforms, eastern Mojave Desert, USA

    NASA Astrophysics Data System (ADS)

    Sweeney, Mark R.; McDonald, Eric V.; Etyemezian, Vicken

    2011-12-01

    The measurement of natural dust emissions from desert landforms is crucial in environmental hazard assessment and field checking the accuracy of global dust models. More than 500 individual dust measurements from eight common desert landforms in southern California were collected using the PI-SWERL (Portable In Situ Wind Erosion Lab). The largest emitters of dust are dry washes (13.787 to 0.007 mg m - 2 s - 1 ), dunes, playa margins, distal alluvial fans, and lacustrine beaches. Low emitters include salt-crusted playas (0.692 to 0.002 mg m - 2 s - 1 ), silt-clay-crusted playas, and desert pavements. High emissions are a function of saltating sand that bombards the surface, liberating dust-sized particles for entrainment. Low dust emissions are primarily a function of surface crusting, gravel armoring, and vegetation density. PI-SWERL measurements reveal that emission rates can vary by at least three orders of magnitude, reflecting local variability in soil texture and continuity of surface crusts. Shear-stress partitioning models can be applied to dust data measured by the PI-SWERL to account for large surface roughness features, such as vegetation. The results presented here give an approximation of the contributions to atmospheric dust loading by landforms in the Mojave Desert, and can potentially be used to improve atmospheric dust models.

  8. TLS in Aeolian Environments: Elucidating Process-Form Feedbacks in Dusty Deserts

    NASA Astrophysics Data System (ADS)

    Nield, J. M.; Wiggs, G.; King, J.; Bryant, R. G.; Eckardt, F. D.; Thomas, D. S. G.; Washington, R.

    2015-12-01

    Playas (or salt pans) have the potential to be major dust and evaporation sources, modifying weather, climate and posing a health risk, but model predictions are confounded by the temporal and spatial heterogeneity of these surfaces. Playas are typically crusted and the shape of these crusts changes through time. Here we show examples of playa crusts monitored by terrestrial laser scanning (TLS) over hours, days, months and years, detecting changes of up to 30 mm/week. This modifies the aerodynamic roughness by as much as 3 mm/week which can change dust emission potential by 350%. Along with surface elevation, we also use TLS to infer relative surface moisture patterns. This novel use of TLS enables the detection of feedbacks between surface roughness, moisture and pattern development. During periods of low temperature and high relative humidity (typically winter evenings), atmospheric, subsurface and surface interactions lead to changes in inter-pore moisture which help to modify roughness, particularly where polygonal ridges have been initiated. On closed, flat surfaces or during warmer spring conditions, these changes are less noticeable. The high resolution and moisture sensitive capabilities of TLS enable us to identify these interactions and feedbacks for the first time.

  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

    2017-01-01

    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. 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.

  11. Surface-sediment dynamics in a dust source from thermal infrared remote sensing

    NASA Astrophysics Data System (ADS)

    Katra, I.; Lancaster, N.

    2007-12-01

    Characteristics of surface sediments are significant factors in modeling dust entrainment and wind erosion, and it is of interest to monitor them using remote sensing in source areas at high spatial and temporal resolution. A time-series of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were acquired for Soda Playa (CA), a modern depositional environment associated with dust emission. Analysis of the multispectral thermal infrared (TIR) images indicates that the type and distribution of the surface sediments can be mapped by linear spectral unmixing techniques. Image-based spectral endmembers extracted from the ASTER five-band surface emissivity data were used to drive fraction images. The spectral-mixture analysis reveals that the mosaic-like pattern of the main sediment types - silica-rich, clay-rich, and salt-rich, changes in time as a consequence of interactions between hydrologic and geomorphic processes in the playa environment. The results highlight the dynamic response of the playa-surface to wind erosion, and suggest that this technique is useful for continuously detecting dust emission potential in sources characterized by a small extension and a complex surface.

  12. Origin of lacustrine rocks of Wilkins Peak Member, Wyoming

    SciTech Connect

    Sullivan, R.

    1985-06-01

    Wilkins Peak Member of the Green River Formation, with its interbeds of trona, oil shale, and dolomitic mudstone, contrasts markedly with the predominantly oilshale and calcitic mudstone sequences of the remainder of the succession. Much discussion has centered on the origin of these lacustrine rocks. A perennial meromictic (stratified) lake model has been replaced in recent years by a playa-lake model. The subsurface stratigraphy, however, was not well known when the models were developed. Paleogeographic reconstruction indicates that the region was subjected to variations in hydrographic conditions mainly in response to climatic fluctuations. During humid subtropical periods, widespread during the deposition of the Tipton Shale Member and Laney Member, the lakes were predominantly open meromictic systems with rivers entering the basin from the north. These environmental conditions were modified during deposition of the Wilkins Peak Member as the climate became more arid, and along the southern margin of the basin, shallow, saline-alkaline playa lakes formed in response to these changes. The widespread occurrence in the subsurface of fluvial clastic sequences of the Wasatch Formation associated with the Wilkins Peak Member would indicate that the playa lakes were frequently flooded and freshened by southern drainage systems. Therefore, the lakes were continuously undergoing modifications under the influence of climatic and possibly tectonic processes.

  13. 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.

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. VIEW OF SUGAR MILL RUINS LOOKING NORTH SHOWING CHIMNEY AT ...

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

    VIEW OF SUGAR MILL RUINS LOOKING NORTH SHOWING CHIMNEY AT LEFT AND MASONRY BASE OF STEAM ENGINE AND CANE MILL AT RIGHT - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  20. 22. Detail interior veiw of window opening and nonoriginal column ...

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

    22. Detail interior veiw of window opening and non-original column supporting roof truss in purging house. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  1. 3. View of partially excavated mill ruins looking NW showing ...

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

    3. View of partially excavated mill ruins looking NW showing unidentified pit in right foreground, masonry base for steam engine and cane mill in left center, purging house and chimney in background. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  2. VIEW OF PARTIALLY EXCAVATED MILL RUINS LOOKING NORTHWEST SHOWING UNIDENTIFIED ...

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

    VIEW OF PARTIALLY EXCAVATED MILL RUINS LOOKING NORTHWEST SHOWING UNIDENTIFIED PIT IN RIGHT FOREGROUND, MASONRY BASE FOR STEAM ENGINE AND CANE MILL IN LEFT CENTER, PURGING HOUSE AND CHIMNEY IN BACKGROUND - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  3. 2. View of sugar mill ruins looking N showing chimney ...

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

    2. View of sugar mill ruins looking N showing chimney at left and masonry base of steam engine and cane mill at right. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  4. 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

  5. 6. View of mill wall ruins looking E showing arched ...

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

    6. View of mill wall ruins looking E showing arched openings where fuel was fed to fire Jamaican Train. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  6. 5. View looking E at unidentified archeological feature possibly ...

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

    5. View looking E at unidentified archeological feature - possibly the underground flue leading from Jamaican Train to chimney. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  7. 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

  8. 46. View of end bay of NW corner of mill ...

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

    46. View of end bay of NW corner of mill ruins showing where flue emerged from area of Jamaican Train. - 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

  9. 7. Detail view of mill wall ruins looking E showing ...

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

    7. Detail view of mill wall ruins looking E showing arched openings for Jamaican Train and archeological excavations at base of wall. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

  10. 1. General view of Motor Pool Building, looking east with ...

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

    1. General view of Motor Pool Building, looking east with view of back side of guard house (Building 121) on right side of photo - U.S. Coast Guard Base, San Juan, Motor Pool, La Puntilla Finalle, San Juan, San Juan Municipio, PR

  11. 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

  12. 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

  13. Community well-being and growth status of indigenous school children in rural Oaxaca, southern Mexico.

    PubMed

    Reyes, Maria Eugenia Peña; Chavez, Guillermo Bali; Little, Bertis B; Malina, Robert M

    2010-07-01

    To evaluate the relationship between community well-being based on an index of marginalization and growth status of indigenous rural school children in Oaxaca. Heights and weights of a cross-sectional sample of 11,454 children, 6-14 years, from schools for indigenous rural children (escuelas albergue) in 158 municipios in Oaxaca were measured in 2007. Tertiles of an index of marginalization were used to classify the 158 municipios into three categories of community well-being: lowest (highest marginalization), low, and moderate (lowest marginalization). Multivariate analysis of covariance, controlling for age, relative isolation and population size, was used to compare body size of children by category of community well-being. Contributions of marginalization, isolation and population size to variation in body size were estimated with sex-specific linear regression. Children from municipios lowest in well-being were shorter and lighter than children from municipios low and moderate in well-being. Marginalization and relative isolation accounted for 23% (boys) and 21% (girls) of the variance in height and for 21% of the variance in weight of girls. Marginalization was the predictor of weight in boys (23%). Community well-being was reflected in the growth status of rural indigenous school children. Compromised growth status was consistent with poor health and nutritional conditions that were and are characteristic of rural areas in the state of Oaxaca. 2010 Elsevier B.V. All rights reserved.

  14. [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.

  15. 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…

  16. 15. REPRODUCTION OF ARMY PHOTOGRAPH, AERIAL VIEW, LOOKING NORTH, SHOWING ...

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

    15. REPRODUCTION OF ARMY PHOTOGRAPH, AERIAL VIEW, LOOKING NORTH, SHOWING WESTERN END OF FORT (OFFICERS QUARTERS, TROOPS QUARTERS, SAN CHRISTOBAL, LA TRINIDAD AND SAN CARLOS). PHOTOGRAPHER AND DATE UNKNOWN. - Castillo de San Christobal, Boulevard Norzagaray, San Juan, San Juan Municipio, PR

  17. 9. Detail view of cane mill showing feed, top and ...

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

    9. Detail view of cane mill showing feed, top and discharge roll driving pinions and main shaft coupling. - Hacienda Azucarera La Esperanza, Steam Engine & Mill, 2.65 Mi. N of PR Rt. 2 Bridge over Manati River, Manati, Manati Municipio, PR

  18. 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

  19. 37. Detail view of center of castiron arch in N ...

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

    37. Detail view of center of cast-iron arch in N room of mill. - 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

  20. 31. Closerin interior view of N room of mill, looking ...

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

    31. Closer-in interior view of N room of mill, looking NW, showing cast-iron columns and arches. - 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

  1. 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

  2. 21. View of N room of mill looking NW through ...

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

    21. View of N room of mill looking NW through arched passageway in wall separating N and S rooms. - 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

  3. 3. Detail view of third bay in E elevation of ...

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

    3. Detail view of third bay in E elevation of sugar mill looking W. - 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

  4. 28. Detail view of small triangular openings (perhaps for ventilation) ...

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

    28. Detail view of small triangular openings (perhaps for ventilation) in top of S wall in center bay of N room of mill. - 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

  5. 17. Detail view of corner of middle bay of N ...

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

    17. Detail view of corner of middle bay of N (rear) elevation looking SE. - 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

  6. 38. View of niche in center bay of N room ...

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

    38. View of niche in center bay of N room in mill ruins in which a painting or tapestry of Santa Elena was hung. - 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

  7. 27. View of interior S wall of N room of ...

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

    27. View of interior S wall of N room of mill showing rows of cast-iron columns and arches. - 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

  8. 5. Detail view of fifth bay in E elevation of ...

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

    5. Detail view of fifth bay in E elevation of sugar mill looking W. - 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

  9. 30. Interior view of N room of mill, looking NW, ...

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

    30. Interior view of N room of mill, looking NW, showing cast-iron columns and arches. - 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

  10. 45. View of end bay of W elevation showing openings ...

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

    45. View of end bay of W elevation showing openings in wall associated with sugar making process. - 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

  11. 32. Symmetrical view of castiron columns and arches, looking W, ...

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

    32. Symmetrical view of cast-iron columns and arches, looking W, in interior of N room of mill. - 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

  12. 19. View of W elevation of mill looking NE showing ...

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

    19. View of W elevation of mill looking NE showing two bays and wall buttress. - 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

  13. 26. Sharply angled view looking N at E wall of ...

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

    26. Sharply angled view looking N at E wall of N room of mill. - 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

  14. 43. Detail view of connection between column top and arch ...

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

    43. Detail view of connection between column top and arch in S room. - 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. 14. Detail view of molding at first floor level on ...

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

    14. Detail view of molding at first floor level on SE corner of mill. - 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. 33. Interior view of N room of mill, looking NW, ...

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

    33. Interior view of N room of mill, looking NW, showing interior of W wall and cast-iron columns and arches. - 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

  17. 6. Detail view of eighth bay in E elevation of ...

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

    6. Detail view of eighth bay in E elevation of sugar mill looking W. - 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

  18. 4. Detail view of fourth bay in E elevation of ...

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

    4. Detail view of fourth bay in E elevation of sugar mill looking W. - 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

  19. 18. View of W elevation of ramp looking NE showing ...

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

    18. View of W elevation of ramp looking NE showing entrances and openings to storage spaces below. - 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

  20. 24. View of N room of mill looking NE through ...

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

    24. View of N room of mill looking NE through arched opening in W elevation. - 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

  1. 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

  2. 7. 3/4 view of sugar mill looking NW showing entry ...

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

    7. 3/4 view of sugar mill looking NW showing entry ramp, S and E elevations. - 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

  3. 35. Detail view of castiron column capitol showing bearing point ...

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

    35. Detail view of cast-iron column capitol showing bearing point of arches. - 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

  4. 12. Detail view of molding at second floor level on ...

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

    12. Detail view of molding at second floor level on SE corner of mill. - 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

  5. Migrants to and in Oaxaca City.

    PubMed

    Rees, M W; Murphy, A D; Morris, E W; Winter, M

    1991-01-01

    "This paper examines migration to Oaxaca City, an intermediate city in southern Mexico, and describes the differences between migrants and non-migrants. The data show that migrants to Oaxaca City tend to come from district capitals rather than more rural municipios. Once in Oaxaca, migrants are not as different from non-migrants as is commonly asserted in the literature." excerpt

  6. Flora of Chihuahuan desertscrub on limestone in northeastern Sonora, Mexico

    Treesearch

    Thomas R. Van Devender; Ana Lilia Reina-Guerrero; J. Jesus. Sanchez-Escalante

    2013-01-01

    Transects were done in desertscrub on limestone to characterize the flora of the westernmost Chihuahuan Desert. Most of the sites (15) were in the Municipios of Agua Prieta and Naco in northeastern Sonora, with single sites near Ascensión, northwestern Chihuahua and east of Douglas in southeastern Arizona. A total of 236 taxa were recorded on transects. Dicot perennial...

  7. 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.…

  8. A new species of Sciurodendrium (Nematoda: Heligmonellidae) in Sciurus aureogaster (Rodentia: Sciuridae) from Morelos, Mexico.

    PubMed

    Falcón-Ordaz, Jorge; Lamothe-Argumedo, Marcos Rafael

    2006-06-01

    Sciurodendrium bravohollisae n. sp. (Heligmonellidae) is described as an intestinal parasite of 2 squirrels, Sciurus aureogaster Cuvier, 1829, collected from Los Robles, Municipio de Tlalnepantla, Morelos State, Mexico. The new species differs from all other congeners in possessing a very well-developed and sacciform genital cone. This is the seventh species described for the genus and the first one recorded in Mexico.

  9. 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…

  10. 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…

  11. 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

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

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

    9. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, 1956 BRIDGE ACROSS DRY MOAT, NORTH SIDE, 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

  13. 4. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, ...

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

    4. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, 1956 DETAIL OF DOORS OF CHAPEL, 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

  14. 6. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, ...

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

    6. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, 1956 HOLY WATER BASIN, CHAPEL OF 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

  15. 8. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, ...

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

    8. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, 1956 BRIDGE ACROSS DRY MOAT, SOUTH SIDE, 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

  16. 10. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, ...

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

    10. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, 1956 GUNDECK ABOVE CHAPEL AND SALLY PORT, 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

  17. 1. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, ...

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

    1. Historic American Buildings Survey, Frederik C. Gjessing, Photographer January, 1956 SALLY PORT OF SAN FELIPE DEL MORRO SEEN FROM BRIDGE ACROSS DRY MOAT. - Castillo de San Felipe del Morro Sally Port & Chapel, Northwest end of San Juan Island, San Juan, San Juan Municipio, PR

  18. 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

  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, VIEW OF SOUTH ABUTMENT. - Puente Rio Hondo, Spanning Hondo River on PR Road 156, Barrio Rio Hondo, Comerio, Comerio Municipio, PR

  20. 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

  1. 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

  2. The Relationship of Land Cover to Aeolian Dust Production at the Jornada Basin, New Mexico, USA

    NASA Astrophysics Data System (ADS)

    Floyd, K. W.; Gill, T. E.; Gillette, D. A.

    2007-12-01

    Vegetation tends to reduce aeolian transport of surface sediments. However, not all vegetation types act in the same way to do so. In general, the more land cover the less erosion will occur; thus grasslands should experience less aeolian erosion than shrublands, which are characterized by patchy cover with open intershrub spaces. Five major ecosystem types are described at the Jornada Basin Long- Term Ecological Research site (Jornada LTER) in south-central New Mexico, USA: mesquite dunes, black grama grasslands, creosote bush shrublands, tarbush alluvial flats, and grass-dominated playas. Here we investigate the dry particle size distribution of material collected by BSNE aeolian particle samplers in 2006 in these five different vegetation types, allowing us to estimate dust production at sites with different land cover. As mesquite and creosote bush continue replacing historical grasslands at Jornada, understanding the characteristics of wind erosion will be important for future management plans. The mesquite sites had the greatest horizontal mass flux, although with substantial variation. M-NORT, a site with large sand dunes, had much greater mass flux than other mesquite sites. For most sites, the dry particle size distributions at 5, 10 and 20 cm heights above the land surface were very similar, dominated by sand, while the distributions for 50 and 100cm heights shifted towards a greater percentage of silt and clay (dust) particles. The playa site and one of three tarbush sites stand out as having the greatest percentages of dust particles, between 33- 52 % of total mass at all heights. After taking into account the differences in mass flux, the mesquite site with the larger dunes and the playa site had the greatest flux of dust-sized particles. These two sites demonstrate different mechanisms of producing dust at the Jornada LTER. The playa is a relatively major dust producer due to its high proportion of fine particles, whereas the mesquite site is a major

  3. Paleoenvironmental and geoarchaeologic implications of late quaternary sediments and paleosols: north-central to southwestern San Juan Basin, New Mexico

    NASA Astrophysics Data System (ADS)

    Smith, Grant D.; McFaul, Michael

    1997-12-01

    Soil/sediment relationships from the West Fork of Gallegos Canyon near Farmington, NM to the Manuelito Plateau northwest of Gallup, NM provide insight into the Late Pleistocene and Holocene history of the north-central to southwestern San Juan Basin. Soil formation suggests six widespread episodes of land-surface stability. The oldest and strongest paleosol is in eolian, alluvial, and playa sediments that were buried between 9560 and 7800 14C yrs B.P. The second oldest paleosol developed within eolian and alluvial sediments and was buried at ca. 4500 14C yrs B.P. Subsequent eolian, alluvial, and playa deposits contain a third paleosol that was buried ca. 3100 14C yrs B.P. In turn, these sediments are mantled by eolian, alluvial, and playa sediments that exhibit remnants of a fourth paleosol that was buried by ca. 2100 14C yrs B.P. A fifth paleosol within eolian and alluvial sediments is associated with Basketmaker III-Pueblo III cultural materials dating from 1300 to 660 14C yrs B.P. The sixth soil/sediment unit consists of eolian and alluvial deposits that date from 660 14C yrs B.P. to the present and exhibits the modern soil. In addition, a very weak paleosol that was buried at ca. 300 14C yrs B.P. was encountered at a few locales. Because of discontinuous burial and preservation, not all of these units are present at every locale within the study area. Several locales across the basin, however, exhibit five to six of these units in stratigraphic succession. The widespread occurrence of these paleosols suggests that six episodes of regional stability and soil formation occurred in the western San Juan Basin during the Holocene.

  4. 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.

  5. 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.

  6. Alluvial fan facies of the Yongchong Basin: Implications for tectonic and paleoclimatic changes during Late Cretaceous in SE China

    NASA Astrophysics Data System (ADS)

    Chen, Liuqin; Steel, Ronald J.; Guo, Fusheng; Olariu, Cornel; Gong, Chenglin

    2017-02-01

    Late Cretaceous continental redbeds, the Guifeng Group of the Yongchong Basin in SE China have been investigated to conduct detailed fan facies description and interpretation. Tectonic activities determined the alluvial fan development along the basin margin, but the alluvial facies was linked with paleoclimate changes. The Guifeng Group is divided into the Hekou, Tangbian and Lianhe formations in ascending order. The Hekou conglomerates are typically polymict, moderately sorted with erosional bases, cut-and-fill features, normal grading and sieve deposits, representing dominant stream-flows on alluvial fans during the initial opening stage of the basin infill. The Tangbian Formation, however, is characterized by structureless fine-grained sediments with dispersed coarse clasts, and couplets of conglomerate and sandstone or siltstone and mudstone, recording a change to a playa and ephemeral lake environments with occasional stream flooding, thus indicating a basin expanding stage. The hallmark of the Lianhe Formation is disorganized, poorly sorted conglomerates lack of erosional bases, and a wide particle-size range from clay to boulders together reflect mud-rich debris-flows accumulating on fans, likely related to reactivation of faulting along the northwestern mountain fronts during a post-rift stage. The depositional system changes from stream-flows up through playa with ephemeral streams to debris-flows during the accumulation of the three formations are thus attributed to different source rocks and climatic conditions. Therefore, the fluvial-dominated fans of the Hekou Formation recorded a subhumid paleoclimate (Coniacian-Santonian Age). The dominant semiarid climate during the Campanian Age produced abundant fine-grained sediments in the playa and ephemeral lake environments of the Tangbian Formation. A climatic change towards more humidity during the late stage of the Guifeng Group (Maastrichtian Age) probably yielded high deposition rate of coarse clasts in

  7. 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

  8. Resolving Codependent Processes Within Natural Dust Devil Vortices

    NASA Astrophysics Data System (ADS)

    Metzger, S. M.; Balme, M.; Farrell, W. M.; Fuerstenau, S.; Greeley, R.; Merrison, J.; Patel, M.; Ringrose, T.; Towner, M.; Zarnecki, J.

    2004-12-01

    The on-going Eldorado Valley Dust Devil Project was expanded this year to include other sites in the Mohave Desert, California, and in northern Nevada on the Black Rock playa. During each field campaign, dust-laden vortices were directly sampled by over 30 instruments on a terrain-following rig that profiled conditions from ground level to over 5m above the surface. On several occasions, dust devils were observed to follow borders between aerodynamically rough (ex. sagebrush or coarse mud-flaked playa surfaces) and smooth terrain (ex. even, undisturbed & undesiccated silt-floored playa surfaces). Regardless of underlying terrain, dust devils rarely formed coherent structure nor could such vortices be sustained when ambient winds dropped below 2 m/s or gusted above 8 m/s (as measured at 2m above ground). Furthermore, vortex formation, rotation, and type were clearly influenced by upstream obstacles, such as range fronts, as much as 10km upwind. Video and high-resolution time-lapse photography are being correlated with the 5 Hz sensor logs to examine the interaction of meteorological conditions (profiled wind speed & direction, pressure, temperature, and humidity) within the vortices. In addition, single-level measurements were recorded for dust impacts and UV occultation (using a sensor suite developed for the Beagle2 Mars Lander), charged particle impacts, and electric fields (horizontal and vertical). These data are still being evaluated. Preliminary results indicate that thermally powered vortices are able to entrain soil material at surprisingly low wind shears and "poorly structured" columns are able to last longer than previously noted. Our research will attempt to decipher the dominant aerodynamic and electric factors that govern dust devil behavior and erosion efficacy.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Online resource for Earth-observing satellite sensor calibration

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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.

  20. The Chilean nitrate deposits.

    USGS Publications Warehouse

    Ericksen, G.E.

    1983-01-01

    The nitrate deposits in the arid Atacama desert of northern Chile consist of saline-cemented surficial material, apparently formed in and near a playa lake that formerly covered the area. Many features of their distribution and chemical composition are unique. The author believes the principal sources of the saline constituents were the volcanic rocks of late Tertiary and Quaternary age in the Andes and that the nitrate is of organic origin. Possible sources of the nitrate, iodate, perchlorate and chromate are discussed. -J.J.Robertson