WorldWideScience

Sample records for southwestern desert paleoclimates

  1. Spatial probability models of fire in the desert grasslands of the southwestern USA

    Science.gov (United States)

    Fire is an important driver of ecological processes in semiarid environments; however, the role of fire in desert grasslands of the Southwestern US is controversial and the regional fire distribution is largely unknown. We characterized the spatial distribution of fire in the desert grassland region...

  2. [Climate implications of terrestrial paleoclimate]. Quaternary Sciences Center, Desert Research Institute annual report, fiscal year 1994/1995

    International Nuclear Information System (INIS)

    Wigand, P.E.

    1995-01-01

    The objective of this study is to collect terrestrial climate indicators for paleoclimate synthesis. The paleobiotic and geomorphic records are being examined for the local and regional impact of past climates to assess Yucca Mountain's suitability as a high-level nuclear waste repository. In particular these data are being used to provide estimates of the timing, duration and extremes of past periods of moister climate for use in hydrological models of local and regional recharge that are being formulated by USGS and other hydrologists for the Yucca Mountain area. The project includes botanical, faunal, and geomorphic components that will be integrated to accomplish this goal. To this end personnel at the Quaternary Sciences Center of the Desert Research Institute in Reno, Nevada are conducting the following activities: Analyses of packrat middens; Analysis of pollen samples; and Determination of vegetation climate relationships

  3. Holocene paleoclimate inferred from salinity histories of adjacent lakes in southwestern Sicily (Italy)

    Science.gov (United States)

    Curry, B Brandon; Henne, Paul; Mezquita-Joanes, Francesc; Marrone, Federico; Pieri, Valentina; La Mantia, Tommaso; Calo, Camilla; Tinner, Willy

    2016-01-01

    Marked uncertainties persist regarding the climatic evolution of the Mediterranean region during the Holocene. For instance, whether moisture availability gradually decreased, remained relatively constant, or increased during the last 7000 years remains a matter of debate. To assess Holocene limnology, hydrology and moisture dynamics, the coastal lakes Lago Preola and Gorgo Basso, located in southwestern Sicily, were investigated through several stratigraphic analyses of ostracodes, including multivariate analyses of assemblages, transfer functions of salinity, and biochemical analyses of valves (Sr/Ca, δ18O and δ13C). During the early Holocene, the Gorgo Basso and Lago Preola ostracode records are similar. After an initial period of moderate salinity (1690–6100 mg/l from ca. 10,000–8190 cal yr BP), syndepositional or diagenetic dissolution of ostracode valves suggests that salinity declined to Greek civilization took root in Sicily (2600 cal yr BP), and it completely dominates the record during Roman occupation (roughly 2100 to 1700 cal yr BP). These freshwater conditions at Gorgo Basso suggest high effective moisture when evergreen olive-oak forests collapsed in response to increased Greco-Roman land use and fire. Ostracode valve geochemistry (Sr/Ca, δ18O) suggests significant changes in early vs. late Holocene hydrochemistry, either as changes in salinity or in the seasonality of precipitation. Harmonizing the autecological and geochemical data from Gorgo Basso suggests the latter was more likely, with relatively more late Holocene precipitation falling during the spring, summer, and fall, than winter compared to the early Holocene. Our ostracode-inferred paleosalinity data indicate that moisture availability did not decline during the late Holocene in the central Mediterranean region. Instead, moisture availability was lowest during the early Holocene, and most abundant during the late Holocene.

  4. Simulating the productivity of desert woody shrubs in southwestern Texas

    Science.gov (United States)

    In the southwestern U.S., many rangelands have converted from native grasslands to woody shrublands dominated by creosotebush (Larrea tridentate) and honey mesquite (Prosopis glandulosa), threatening ecosystem health. Both creosotebush and mesquite have well-developed long root systems that allow t...

  5. Land subsidence in the southwestern Mojave Desert, California, 1992–2009

    Science.gov (United States)

    Brandt, Justin; Sneed, Michelle

    2017-07-19

    Groundwater has been the primary source of domestic, agricultural, and municipal water supplies in the southwestern Mojave Desert, California, since the early 1900s. Increased demands on water supplies have caused groundwater-level declines of more than 100 feet (ft) in some areas of this desert between the 1950s and the 1990s (Stamos and others, 2001; Sneed and others, 2003). These water-level declines have caused the aquifer system to compact, resulting in land subsidence. Differential land subsidence (subsidence occurring at different rates across the landscape) can alter surface drainage routes and damage surface and subsurface infrastructure. For example, fissuring across State Route 247 at Lucerne Lake has required repairs as has pipeline infrastructure near Troy Lake.Land subsidence within the Mojave River and Morongo Groundwater Basins of the southwestern Mojave Desert has been evaluated using InSAR, ground-based measurements, geology, and analyses of water levels between 1992 and 2009 (years in which InSAR data were collected). The results of the analyses were published in three USGS reports— Sneed and others (2003), Stamos and others (2007), and Solt and Sneed (2014). Results from the latter two reports were integrated with results from other USGS/ MWA cooperative groundwater studies into the broader scoped USGS Mojave Groundwater Resources Web site (http://ca.water.usgs.gov/ mojave/). This fact sheet combines the detailed analyses from the three subsidence reports, distills them into a longer-term context, and provides an assessment of options for future monitoring.

  6. Deserts

    Science.gov (United States)

    Belnap, Jayne; Webb, Robert H.; Esque, Todd; Brooks, Matthew L.; DeFalco, Lesley; MacMahon, James A.

    2016-01-01

    The deserts of California (Lead photo, Fig. 1) occupy approximately 38% of California’s landscape (Table 1) and consist of three distinct deserts: the Great Basin Desert, Mojave Desert, and Colorado Desert, the latter of which is a subdivision of the Sonoran Desert (Brown and Lowe 1980). The wide range of climates and geology found within each of these deserts result in very different vegetative communities and ecosystem processes and therefore different ecosystem services. In deserts, extreme conditions such as very high and low temperatures and very low rainfall result in abiotic factors (climate, geology, geomorphology, and soils) controlling the composition and function of ecosystems, including plant and animal distributions. This is in contrast to wetter and milder temperatures found in other ecosystems, where biotic interactions are the dominant driving force. However, despite the harsh conditions in deserts, they are home to a surprisingly large number of plants and animals. Deserts are also places where organisms display a wide array of adaptations to the extremes they encounter, providing some of the best examples of Darwinian selection (MacMahon and Wagner 1985, Ward 2009). Humans have utilized these regions for thousands of years, despite the relatively low productivity and harsh climates of these landscapes. Unlike much of California, most of these desert lands have received little high-intensity use since European settlement, leaving large areas relatively undisturbed. Desert landscapes are being altered, however, by the introduction of fire following the recent invasion of Mediterranean annual grasses. As most native plants are not fire-adapted, they Many do not recover, whereas the non-native grasses flourish. Because desert lands are slow to recover from disturbances, energy exploration and development, recreational use, and urban development will alter these landscapes for many years to come. This chapter provides a brief description of where the

  7. Ecological Observations of Native Geocoris pallens and G. punctipes Populations in the Great Basin Desert of Southwestern Utah

    Directory of Open Access Journals (Sweden)

    Meredith C. Schuman

    2013-01-01

    Full Text Available Big-eyed bugs (Geocoris spp. Fallén, Hemiptera: Lygaeidae are ubiquitous, omnivorous insect predators whose plant feeding behavior raises the question of whether they benefit or harm plants. However, several studies have investigated both the potential of Geocoris spp. to serve as biological control agents in agriculture and their importance as agents of plant indirect defense in nature. These studies have demonstrated that Geocoris spp. effectively reduce herbivore populations and increase plant yield. Previous work has also indicated that Geocoris spp. respond to visual and olfactory cues when foraging and choosing their prey and that associative learning of prey and plant cues informs their foraging strategies. For these reasons, Geocoris spp. have become models for the study of tritrophic plant-herbivore-predator interactions. Here, we present detailed images and ecological observations of G. pallens Stål and G. punctipes (Say native to the Great Basin Desert of southwestern Utah, including observations of their life histories and color morphs, dynamics of their predatory feeding behavior and prey choice over space and time, and novel aspects of Geocoris spp.’s relationships to their host plants. These observations open up new areas to be explored regarding the behavior of Geocoris spp. and their interactions with plant and herbivore populations.

  8. Recurrence of water bodies in the hyperarid core of the Atacama Desert - New insights into the Late Pleistocene paleoclimate history of Northern Chile

    Science.gov (United States)

    Diederich, J. L.; Wennrich, V.; Fernández Galego, E.; Ritter, B.; Brill, D.; Niemann, K.; Rolf, C.; Melles, M.

    2017-12-01

    The Atacama Desert of northern Chile is regarded as the driest desert on Earth. Although still controversially discussed, overall arid to hyperarid conditions in the Atacama are thought to have persisted at least since the early Miocene, but were frequently punctuated by pluvial phases. The knowledge of past changes in humidity is strongly hampered by the fact that sediment records from the central Atacama Desert, which enable longer-scale precipitation reconstructions, are rare and mostly restricted to the Miocene/Pliocene or the late Pleistocene <50 kyrs. In this study, we focus on a sediment record from the hyperarid core of the Atacama Desert, derived from a tectonically blocked clay pan in the Coastal Cordillera (20°04'33.64"S, 69°55'01.75"W). This clay pan `Huara' has been initially investigated by a geophysical survey in spring 2015, followed by drilling of a short core (HU-III) covering the uppermost 4 m of sediment. Initial results of the ground penetrating radar (GPR) and horizontal to vertical (H/V) spectral ratio measurements indicate well-stratified sediment bodies in the basin with a maximum sediment infill of 30 ± 4 m. The chronology of core HU-III was established by a combination of optically stimulated luminescence (OSL) and paleomagnetic dating. The sedimentological and geochemical data of core HU-III as well as it's sediment geophysical properties indicate the primary accumulation of fine-grained sediments over the past ca. 50 kyrs, interpreted to be deposited under arid conditions with only sporadic precipitation. Intercalated coarser horizons indicate several periods of semiarid climate conditions, causing multiple phases of local alluvial deposition from the interior catchment area into the clay pan. The results are in agreement with a cosmogenic nuclide study from an adjacent meander system, indicating that the whole sediment sequence of the Huara clay pan covers the regional climate history of the past 500 - 700 kyrs.

  9. Simulating southwestern U.S. desert dust influences on supercell thunderstorms

    Science.gov (United States)

    Lerach, David G.; Cotton, William R.

    2018-05-01

    Three-dimensional numerical simulations were performed to evaluate potential southwestern U.S. dust indirect microphysical and direct radiative impacts on a real severe storms outbreak. Increased solar absorption within the dust plume led to modest increases in pre-storm atmospheric stability at low levels, resulting in weaker convective updrafts and less widespread precipitation. Dust microphysical impacts on convection were minor in comparison, due in part to the lofted dust concentrations being relatively few in number when compared to the background (non-dust) aerosol population. While dust preferentially serving as cloud condensation nuclei (CCN) versus giant CCN had opposing effects on warm rain production, both scenarios resulted in ample supercooled water and subsequent glaciation aloft, yielding larger graupel and hail. Associated latent heating from condensation and freezing contributed little to overall updraft invigoration. With reduced rain production overall, the simulations that included dust effects experienced slightly reduced grid-cumulative precipitation and notably warmer and spatially smaller cold pools. Dust serving as ice nucleating particles did not appear to play a significant role. The presence of dust ultimately reduced the number of supercells produced but allowed for supercell evolution characterized by consistently higher values of relative vertical vorticity within simulated mesocyclones. Dust radiative and microphysical effects were relatively small in magnitude when compared to those from altering the background convective available potential energy and vertical wind shear. It is difficult to generalize such findings from a single event, however, due to a number of case-specific environmental factors. These include the nature of the low-level moisture advection and characteristics of the background aerosol distribution.

  10. Annual report on paleoclimate studies for the Yucca Mountain project site characterization conducted by the Desert Research Institute for the Department of Energy

    International Nuclear Information System (INIS)

    1994-01-01

    The prospect that Yucca Mountain may become a repository for high-level radionuclides with especially long half-lives means that the intended waste containment area must be well beyond the reach of the hydrologic system for at least ten millennia. Through the integration of several avenues of paleoclimatic proxy data, the authors intend to arrive at definite conclusions regarding rates of change, and extremes and stabilities of past climate regimes. These will in turn lead to rough estimates of: the amounts of rainfall available for recharge during past periods of effectively wetter climate, and the durations and frequencies of recharge periods. The paper gives summaries of the following studies: Late Quaternary and Holocene climate derived from vegetation history and plant cellulose stable isotope records from the Great basin of western North America; Accomplishments of paleofaunal studies, 1993--1994; Geomorphology studies in the Great Basin; Alluvial fan response to climatic change, Buena Vista Valley, central Nevada; Sedimentology, stratigraphy, and chronology of lacustrine deposition in the Fernley Basin, west-central Nevada; Tree-rings, lake chronologies, alluvial sequences and climate--Implications for Great Basin paleoenvironmental studies; Stable isotopic validation studies--Fossil snails; and Late Pleistocene and Holocene eolian activity in the Mojave Desert

  11. Post-Closure Challenges of U.S. Department of Energy Sites in Desert Environments of the Southwestern United States - 12095

    Energy Technology Data Exchange (ETDEWEB)

    Gil, April; Steckley, Deborah [U.S. Department of Energy Office of Legacy Management (United States); Gauthier, Cassie; Miller, David [S.M. Stoller Company, Contractor to the U.S. Department of Energy (United States)

    2012-07-01

    U.S. Department of Energy (DOE) sites located in harsh desert environments of the Four Corners region of the southwestern United States require diligence and continual maintenance to ensure the remediation systems function as designed to protect human health and the environment. The geology and climate of this area create issues that are unique to these sites. Geologic formations contain naturally occurring constituents that are often the same as the residual contaminants remaining from historical milling activities at the sites. Although annual precipitation is low, when precipitation events occur they can be of extreme intensity, resulting in erosion and flooding that can quickly destroy infrastructure and rapidly change site conditions. Winds can cause sand storms and sand mounding that effect site features. These challenging environmental conditions, along with the remote locations of the sites, require active management beyond what was originally envisioned for uranium disposal sites to address concerns in a safe and cost-effective manner. The unique environment of the Four Corners region creates many challenges to the LTSM of LM sites in southwestern United States. The remediation efforts and approaches to infrastructure have to be specifically structured to work in this environment. Often, the systems and structures have to be modified based on lessons learned on how to best adapt to these difficult conditions and remote locations. These sites require continual maintenance and additional efforts compared to many other LM sites. (authors)

  12. Moisture variation inferred from a nebkha profile correlates with vegetation changes in the southwestern Mu Us Desert of China over one century.

    Science.gov (United States)

    Li, Jinchang; Zhao, Yanfang; Han, Liuyan; Zhang, Guoming; Liu, Rentao

    2017-11-15

    We inferred moisture variations from the early 1930s to the early 2010s in the southwestern Mu Us Desert of China using Rb/Sr ratio, chemical index of alteration (CIA), and organic matter (OM) content in a nebkha profile. Our results showed that the variations in moisture may have been the main factor that controlled vegetation recovery or degradation, and we believe that gradual vegetation recovery was notable throughout the study area during the past 80years, despite two notable degradation stages during the mid-1950s and the mid-1980s. The Rb/Sr ratio, CIA, and OM content revealed that moisture levels increased during the study period, though with large interannual variations. During the early stage of nebkha formation, the moisture variations were controlled by unusually low precipitation. Thereafter, the precipitation, pan evaporation and temperature determined together moisture variations, but the key factor determining moisture variations was different during different periods. The moisture variations trend revealed in this study may not be restricted to this region as it was similar with the adjacent Mongolian Plateau. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Modeling wind-blown desert dust in the southwestern United States for public health warning: A case study

    Science.gov (United States)

    Yin, Dazhong; Nickovic, Slobodan; Barbaris, Brian; Chandy, Beena; Sprigg, William A.

    A model for simulating desert dust cycle was adapted and applied for a dust storm case in the southwest United States (US). This is an initial test of the model's capability as part of a future public health early warning system. The modeled meteorological fields, which drive a dust storm, were evaluated against surface and upper-air measurement data. The modeled dust fields were compared with satellite images, in situ surface PM2.5 and PM10 data, and visibility data in the areas affected by the dust event. The model predicted meteorological fields reasonably well. The modeled surface and upper-air field patterns were in agreement with the measured ones. The vertical profiles of wind, temperature, and humidity followed closely with the observed profiles. Statistical analyses of modeled and observed meteorological variables at surface sites showed fairly good model performance. The modeled dust spatial distributions were comparable with the satellite-observed dust clouds and the reduced visibility patterns. Most encouragingly, the model-predicted and observed PM2.5 peak hours matched reasonably well. The model produced better PM2.5 peak hours than PM10 peak hours. The temporal varying trends of daily and hourly PM2.5 and PM10 concentrations at most of the measurement sites were similar to those observed. Discrepancies between the values of the modeled and the measured surface PM2.5 and PM10 concentrations differed with time and location. Sometimes the modeled and measured concentrations can have one order of magnitude differences. These revealed there were possible deficiencies in the simulation of the dust production strength and location, and the representation of dust particle size in the modeling. Better land surface data and size representation of the dust production are expected to further improve model performance.

  14. An occupancy-based quantification of the highly imperiled status of desert fishes of the southwestern United States.

    Science.gov (United States)

    Budy, Phaedra; Conner, Mary M; Salant, Nira L; Macfarlane, William W

    2015-08-01

    Desert fishes are some of the most imperiled vertebrates worldwide due to their low economic worth and because they compete with humans for water. An ecological complex of fishes, 2 suckers (Catostomus latipinnis, Catostomus discobolus) and a chub (Gila robusta) (collectively managed as the so-called three species) are endemic to the U.S. Colorado River Basin, are affected by multiple stressors, and have allegedly declined dramatically. We built a series of occupancy models to determine relationships between trends in occupancy, local extinction, and local colonization rates, identify potential limiting factors, and evaluate the suitability of managing the 3 species collectively. For a historical period (1889-2011), top performing models (AICc) included a positive time trend in local extinction probability and a negative trend in local colonization probability. As flood frequency decreased post-development local extinction probability increased. By the end of the time series, 47% (95% CI 34-61) and 15% (95% CI 6-33) of sites remained occupied by the suckers and the chub, respectively, and models with the 2 species of sucker as one group and the chub as the other performed best. For a contemporary period (2001-2011), top performing (based on AICc ) models included peak annual discharge. As peak discharge increased, local extinction probability decreased and local colonization probability increased. For the contemporary period, results of models that split all 3 species into separate groups were similar to results of models that combined the 2 suckers but not the chub. Collectively, these results confirmed that declines in these fishes were strongly associated with water development and that relative to their historic distribution all 3 species have declined dramatically. Further, the chub was distinct in that it declined the most dramatically and therefore may need to be managed separately. Our modeling approach may be useful in other situations in which targeted

  15. A review of Cordylus machadoi (Squamata: Cordylidae) in southwestern Angola, with the description of a new species from the Pro-Namib desert.

    Science.gov (United States)

    Stanley, Edward L; Ceríaco, Luis M P; Bandeira, Suzana; Valerio, Hilaria; Bates, Michael F; Branch, William R

    2016-01-07

    The girdled lizard genus Cordylus is represented in Angola by two species, Cordylus angolensis and C. machadoi, separated from their nearest congeners by over 700 km. Here we describe a new species, Cordylus namakuiyus sp. nov., endemic to the arid lowlands west of the southern Angolan escarpment. Phylogenetic analysis using three mitochondrial and eight nuclear genes shows that the low-elevation forms and the proximate, high-elevation species C. machadoi are genetically divergent and reciprocally monophyletic, and together form the earliest diverging lineage of the northern Cordylus clade. Morphological data, collected using computed tomography and traditional techniques (scalation and morphology), identify consistent phenotypic differences between these high- and low-elevation species and allows for a detailed description of the osteology and osteodermal arrangements of the new species. A series of 50 specimens, collected during the 1925 Vernay expedition to southwestern Angola and housed at the American Museum of Natural History, are assigned to the new species, although the identity of Cordylus from northern Namibia remains ambiguous and requires further investigation.

  16. Ocean-atmosphere forcing of South American tropical paleoclimate, LGM to present

    Science.gov (United States)

    Baker, P. A.; Fritz, S. C.; Dwyer, G. S.; Rigsby, C. A.; Silva, C. G.; Burns, S. J.

    2012-12-01

    Because of many recent terrestrial paleoclimatic and marine paleoceanographic records, late Quaternary South American tropical paleoclimate is as well understood as that anywhere in the world. While lessons learned from the recent instrumental record of climate are informative, this record is too short to capture much of the lower frequency variability encountered in the paleoclimate records and much of the observed paleoclimate is without modern analogue. This paleoclimate is known to be regionally variable with significant differences both north and south of the equator and between the western high Andes and eastern lowlands of the Amazon and Nordeste Brazil. Various extrinsic forcing mechanisms affected climate throughout the period, including global concentrations of GHGs, Northern Hemisphere ice sheet forcing, seasonal insolation forcing of the South American summer monsoon (SASM), millennial-scale Atlantic forcing, and Pacific forcing of the large-scale Walker circulation. The magnitude of the climate response to these forcings varied temporally, largely because of the varying amplitude of the forcing itself. For example, during the last glacial, large-amplitude north Atlantic forcing during Heinrich 1 and the LGM itself, led to wet (dry) conditions south (north) of the equator. During the Holocene, Atlantic forcing was lower amplitude, thus seasonal insolation forcing generally predominated with a weaker-than-normal SASM during the early Holocene resulting in dry conditions in the south-western tropics and wet conditions in the eastern lowlands and Nordeste; in the late Holocene seasonal insolation reached a maximum in the southern tropics and climate conditions reversed.

  17. Gopherus agassizii: Desert tortoise

    Science.gov (United States)

    Berry, Kristen H.; Swingland, Ian Richard; Klemens, Michael W.

    1989-01-01

    The desert tortoise is one of four allopatric North American tortoises. It occurs in the Mojave and Sonoran deserts of the southwestern United States and Mexico.Auffenberg (1976) divided the genus Gopherus (consisting of four species, G. agassizi, G. berlandieri, G.flavomarginatus, and G. polyphemus) in two osteological groups. Bramble (1982), using morphological and palaeontological data, divided the genus Gopherus into two separate complexes, each with two species. He established a new genus, Scaptochelys, for agassizi and berlandieri, retaining Gopherus for polyphemus and flavomarginatus. Bour and Dubois (1984) noted that Xerobates Agassiz had priority over Scaptochelys Bramble. Using mitochondrial DNA (mtDNA), Lamb et al. (1989) evaluated the evolutionary relationships of the North American tortoises, particularly the desert tortoise. They concluded that the mtDNA analysis provides strong support for generic recognition of the two distinct species groups described by Bramble (1982).Until a few decades ago, the desert tortoise was widespread at lower elevations throughout the Mojave and Sonoran deserts of the U.S.A. In the northern and western parts of the geographic range, large and relatively homogeneous populations with densities exceeding 1,000/sq km extended throughout parts of California, and probably into Nevada and Utah. In terms of biomass, the tortoise played an important role in the ecosystems. In most areas, numbers have declined dramatically and the extent of populations has been reduced. Most populations are now isolated and low in numbers. Conservation of the desert tortoise is a highly visible and political issue in the U.S.A., but not in Mexico.

  18. Paleoclimatic implications of micromorphic features of a polygenetic soil in the Monegros Desert (NE-Spain Implicaciones paleoclimáticas de los rasgos micromorfológicos de un suelo policíclico en el Desierto de Monegros (NE-España Implicações paleoclimáticas das características micromorfológicas de um solo policíclico no Deserto de Monegros (NE-Espanha

    Directory of Open Access Journals (Sweden)

    David Badía

    2013-07-01

    Full Text Available Pedofeatures can be repositories of information about soil forming factors such as climate. The aim of this work is to provide a model of interpretation of a polygenetic soil in the Monegros desert (Ebro Basin, NE-Spain and its relationship to environmental changes during the Quaternary. To achieve this goal, the physical, chemical, mineralogical and especially the micromorphic pedofeatures of this profile were studied. Carbonate accumulations extend into all of the horizons of the profile. The paleosol has a thick petrocalcic horizon at the top, with a massive-laminar structure comprising layers of micrite and sparite that sometimes form pendants. Towards its base, the petrocalcic horizon contains a spaced framework of orthic micrite nodules packed between relatively pure micritic laminar bands. Below the petrocalcic horizon, coatings and infillings of microcrystalline calcite occur in old channels, and soft concretions (some of them geodic indicate an in situ accumulation process (Bkc, calcic horizon. Another calcic horizon with orthic nodules of calcite, impregnative and diffuse (Ckc, is present at the bottom part of the profile. Between the two nodular calcic horizons, two recarbonated argic horizons are found (Btkc and Btk with coarse orthic nodules of dense micrite superimposed on textural pedofeatures. These textural micromorphic pedofeatures are: (1 interbedded microlaminated clay pockets not associated with current or past pores and (2 microlaminated clay and silt (dusty clay present as weakly oriented coatings on channel walls. Reduction pedofeatures are associated with textural ones: (1 coatings of manganese oxides around pore channels and cracks, and (2 nodules of manganese and iron oxides within the peds. The presence of calcic horizons alternating with argic horizons, all positioned below the petrocalcic horizon, confirm fluctuations in paleohydrological conditions in the Pleistocene. Its presence indicates that the oldest soil

  19. Merging science and management in a rapidly changing world: Biodiversity and management of the Madrean Archipelago III and 7th Conference on Research and Resource Management in the Southwestern Deserts; 2012 May 1-5; Tucson, AZ

    Science.gov (United States)

    Gerald J. Gottfried; Peter F. Ffolliott; Brooke S. Gebow; Lane G. Eskew; Loa C. Collins

    2013-01-01

    The Madrean Archipelago or Sky Islands region of the southwestern United States and northern Mexico is recognized for its unique biological diversity, natural beauty, and cultural heritage. This 2012 conference brought together scientists, managers, students, and other interested parties from the United States and Mexico to share their knowledge and passion about the...

  20. Paleoclimate validation of a numerical climate model

    International Nuclear Information System (INIS)

    Schelling, F.J.; Church, H.W.; Zak, B.D.; Thompson, S.L.

    1994-01-01

    An analysis planned to validate regional climate model results for a past climate state at Yucca Mountain, Nevada, against paleoclimate evidence for the period is described. This analysis, which will use the GENESIS model of global climate nested with the RegCM2 regional climate model, is part of a larger study for DOE's Yucca Mountain Site Characterization Project that is evaluating the impacts of long term future climate change on performance of the potential high level nuclear waste repository at Yucca Mountain. The planned analysis and anticipated results are presented

  1. Prescribed burning to affect a state transition in a shrub-encroached desert grassland

    Science.gov (United States)

    Prescribed burning is a commonly advocated and historical practice for control of woody species encroachment into grasslands on all continents. However, desert grasslands of the southwestern United States often lack needed herbaceous fuel loads for effective prescriptions, dominant perennial gramin...

  2. Paleoclimates: Understanding climate change past and present

    Science.gov (United States)

    Cronin, Thomas M.

    2010-01-01

    The field of paleoclimatology relies on physical, chemical, and biological proxies of past climate changes that have been preserved in natural archives such as glacial ice, tree rings, sediments, corals, and speleothems. Paleoclimate archives obtained through field investigations, ocean sediment coring expeditions, ice sheet coring programs, and other projects allow scientists to reconstruct climate change over much of earth's history. When combined with computer model simulations, paleoclimatic reconstructions are used to test hypotheses about the causes of climatic change, such as greenhouse gases, solar variability, earth's orbital variations, and hydrological, oceanic, and tectonic processes. This book is a comprehensive, state-of-the art synthesis of paleoclimate research covering all geological timescales, emphasizing topics that shed light on modern trends in the earth's climate. Thomas M. Cronin discusses recent discoveries about past periods of global warmth, changes in atmospheric greenhouse gas concentrations, abrupt climate and sea-level change, natural temperature variability, and other topics directly relevant to controversies over the causes and impacts of climate change. This text is geared toward advanced undergraduate and graduate students and researchers in geology, geography, biology, glaciology, oceanography, atmospheric sciences, and climate modeling, fields that contribute to paleoclimatology. This volume can also serve as a reference for those requiring a general background on natural climate variability.

  3. Speleothem Paleoclimate Records from the Floridian Panhandle

    Science.gov (United States)

    Froelich, P. N.; Kowalczk, A. J.; McCardle, D.; Tibbetts, N.

    2007-12-01

    Geochemical time-series constructed from speleothem records provide a high resolution view into paleoclimate conditions temporally unmatched by deep ocean sediment and ice core records. The potential of speleothem records is vast with immense spatial and temporal resolution. One surprise to the speleothem paleoclimate community is the absence of high resolution speleothem isotope and trace element records from Florida, an area of extensive karstic geology, a plethora of caves, and monsoon-like climate. Two stalagmites collected from Brooks Quarry Cave, recently opened in Marianna, FL will provide one of the first Holocene speleothem climate records from the Southeast. Speleothem BC-1 is a 71 cm calcite stalagmite collected in situ. Speleothem BC-2 is a 6.1 cm stalagmite collected inside the quarried entrance to the cave. Both dripstones are banded and laminated at what appear to be 11-year cycles (dating in progress). If these are annual "sparves" (speleothem varves), the growth rates are approximately 100 μm per year. BC-1 would extend through much of the Holocene. RGB scans along the polished length of the growth axis reveal color cyclicity related to bundles of these bands. Isotope records from BC-2 reveal a multi-year record showing a variation of -2.7 ‰ to -6 ‰ in δ18O and -3.7 ‰ to -9.1‰ in δ13C, with no correlation between the two. High resolution multi-element laser ablation scans across 8 "sparves" (2.3 mm length) reveals co-variation in U and Ba with other elements showing weaker banding correlations with "clays" (Si, Fe, Mn, Ce, Rb). Photomicrographs of the laser tracks show correlation of visible "sparves" to chemical variations. Medical CT imaging techniques were applied to sample BC-1using a GE Lightspeed Plus CT scanner at maximum power (140 kV, 565 mA) and medium resolution (0.6 mm per scan slice) to view density differences and pore spaces inside the calcite matrix. CT technology reveals a porous nature of the calcite matrix in the lower

  4. Gopherus agassizii (Desert Tortoise). Non-native seed dispersal

    Science.gov (United States)

    Ennen, J.R.; Loughran, Caleb L.; Lovich, Jeffrey E.

    2011-01-01

    Sahara Mustard (Brassica tournefortii) is a non-native, highly invasive weed species of southwestern U.S. deserts. Sahara Mustard is a hardy species, which flourishes under many conditions including drought and in both disturbed and undisturbed habitats (West and Nabhan 2002. In B. Tellman [ed.], Invasive Plants: Their Occurrence and Possible Impact on the Central Gulf Coast of Sonora and the Midriff Islands in the Sea of Cortes, pp. 91–111. University of Arizona Press, Tucson). Because of this species’ ability to thrive in these habitats, B. tournefortii has been able to propagate throughout the southwestern United States establishing itself in the Mojave and Sonoran Deserts in Arizona, California, Nevada, and Utah. Unfortunately, naturally disturbed areas created by native species, such as the Desert Tortoise (Gopherus agassizii), within these deserts could have facilitated the propagation of B. tournefortii. (Lovich 1998. In R. G. Westbrooks [ed.], Invasive Plants, Changing the Landscape of America: Fact Book, p. 77. Federal Interagency Committee for the Management of Noxious and Exotic Weeds [FICMNEW], Washington, DC). However, Desert Tortoises have never been directly observed dispersing Sahara Mustard seeds. Here we present observations of two Desert Tortoises dispersing Sahara Mustard seeds at the interface between the Mojave and Sonoran deserts in California.

  5. Fog water chemistry in the Namib desert, Namibia

    Science.gov (United States)

    Eckardt, Frank D.; Schemenauer, Robert S.

    This study documents the ion concentrations and ion enrichment relative to sea water, in Namib Desert fog water, with the purpose of establishing its suitability for future fogwater collection schemes, while also examining claims that Namib Desert fog water carries exceptionally high concentrations of sulphate, which may be responsible for the formation of gypsum deposits in the desert. The work suggests that Namibian fog water is at least as clean as has been reported from other coastal deserts in South America and Arabia, and provides a source of very clean water for the coastal desert region of south-western Africa. It does not appear that fog is an efficient sulphur source for the formation of the gypsum deposits, unless rare events with high concentrations of marine sulphur compounds occur.

  6. Ground-water recharge from small intermittent streams in the western Mojave Desert, California: Chapter G in Ground-water recharge in the arid and semiarid southwestern United States (Professional Paper 1703)

    Science.gov (United States)

    Izbicki, John A.; Johnson, Russell U.; Kulongoski, Justin T.; Predmore, Steven; Stonestrom, David A.; Constantz, Jim; Ferré, Ty P.A.; Leake, Stanley A.

    2007-01-01

    Population growth has impacted ground-water resources in the western Mojave Desert, where declining water levels suggest that recharge rates have not kept pace with withdrawals. Recharge from the Mojave River, the largest hydrographic feature in the study area, is relatively well characterized. In contrast, recharge from numerous smaller streams that convey runoff from the bounding mountains is poorly characterized. The current study examined four representative streams to assess recharge from these intermittent sources. Hydraulic, thermal, geomorphic, chemical, and isotopic data were used to study recharge processes, from streamflow generation and infiltration to percolation through the unsaturated zone. Ground-water movement away from recharge areas was also assessed.Infiltration in amounts sufficient to have a measurable effect on subsurface temperature profiles did not occur in every year in instrumented study reaches. In addition to streamflow availability, results showed the importance of sediment texture in controlling infiltration and eventual recharge. Infiltration amounts of about 0.7 meters per year were an approximate threshold for the occurrence of ground-water recharge. Estimated travel times through the thick unsaturated zones underlying channels reached several hundred years. Recharging fluxes were influenced by stratigraphic complexity and depositional dynamics. Because of channel meandering, not all water that penetrates beneath the root zone can be assumed to become recharge on active alluvial fans.Away from study washes, elevated chloride concentrations and highly negative water potentials beneath the root zone indicated negligible recharge from direct infiltration of precipitation under current climatic conditions. In upstream portions of washes, generally low subsurface chloride concentrations and near-zero water potentials indicated downward movement of water toward the water table, driven primarily by gravity. Recharging conditions did not

  7. Algae from the arid southwestern United States: an annotated bibliography

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, W.H.; Gaines, S.R.

    1983-06-01

    Desert algae are attractive biomass producers for capturing solar energy through photosynthesis of organic matter. They are probably capable of higher yields and efficiencies of light utilization than higher plants, and are already adapted to extremes of sunlight intensity, salinity and temperature such as are found in the desert. This report consists of an annotated bibliography of the literature on algae from the arid southwestern United States. It was prepared in anticipation of efforts to isolate desert algae and study their yields in the laboratory. These steps are necessary prior to setting up outdoor algal culture ponds. Desert areas are attractive for such applications because land, sunlight, and, to some extent, water resources are abundant there. References are sorted by state.

  8. A Paleolatitude Calculator for Paleoclimate Studies.

    Directory of Open Access Journals (Sweden)

    Douwe J J van Hinsbergen

    Full Text Available Realistic appraisal of paleoclimatic information obtained from a particular location requires accurate knowledge of its paleolatitude defined relative to the Earth's spin-axis. This is crucial to, among others, correctly assess the amount of solar energy received at a location at the moment of sediment deposition. The paleolatitude of an arbitrary location can in principle be reconstructed from tectonic plate reconstructions that (1 restore the relative motions between plates based on (marine magnetic anomalies, and (2 reconstruct all plates relative to the spin axis using a paleomagnetic reference frame based on a global apparent polar wander path. Whereas many studies do employ high-quality relative plate reconstructions, the necessity of using a paleomagnetic reference frame for climate studies rather than a mantle reference frame appears under-appreciated. In this paper, we briefly summarize the theory of plate tectonic reconstructions and their reference frames tailored towards applications of paleoclimate reconstruction, and show that using a mantle reference frame, which defines plate positions relative to the mantle, instead of a paleomagnetic reference frame may introduce errors in paleolatitude of more than 15° (>1500 km. This is because mantle reference frames cannot constrain, or are specifically corrected for the effects of true polar wander. We used the latest, state-of-the-art plate reconstructions to build a global plate circuit, and developed an online, user-friendly paleolatitude calculator for the last 200 million years by placing this plate circuit in three widely used global apparent polar wander paths. As a novelty, this calculator adds error bars to paleolatitude estimates that can be incorporated in climate modeling. The calculator is available at www.paleolatitude.org. We illustrate the use of the paleolatitude calculator by showing how an apparent wide spread in Eocene sea surface temperatures of southern high

  9. Soil micromorphogenesis and Early Holocene paleoclimate at the desert margin of Southern Arabia Micromorfoedafogénesis y paleoclima del Holoceno Inferior en el márgen desértico del sur de Arabia Micromorfogénese do solo e paleoclima inicial do Holoceno na margem deserta do Sul da Arábia

    Directory of Open Access Journals (Sweden)

    Peter Kühn

    2013-07-01

    Full Text Available The Ramlat as-Sab'atayn desert margin near Ma'rib, Yemen, displays well-preserved Early Holocene paleosols that are documented by micromorphological and pedological data. The buried soils, which are represented by Ahb horizons, indicate soil formation mostly before 8.3 cal ka BP. In contrast, sandy cover sediments without signs of pedogenesis appeared between 8.3 and 6.6 cal ka BP due to increasing aridity. Characteristic micromorphological features of the cover sediments are a single grain microstructure, crystallitic b-fabric, predominant occurrence of fresh sideromelane, and remnants of microlayers. Micromorphological pedogenic features in the buried Ah horizons include a subangular blocky microstructure, undifferentiated b-fabric as a result of enrichment of organic matter and decalcification, and the predominant occurrence of completely altered sideromelane. Most of these horizons appeared to be nearly completely decalcified so that in parts a stipple speckled b-fabric and neoformed clay coatings could be detected as a result of stronger weathering and soil formation. Pedogenic data provide important information about Holocene climate fluctuations, including the amount of precipitation, which was calculated on the basis of geochemical data from buried A, AB and B horizons. The buried paleosols represent moist climate conditions with precipitation ranging from 400 to 600 mm a-1.En los márgenes del desierto Ramlat as-Sab'atayn, cerca de Ma'rib (Yemen, se encuentran paleosuelos del Holoceno Inferior bien conservados que se documentan con datos micromorfológicos y edáficos. Los suelos enterrados, representados por horizontes Ahb, indican que se formaron mayoritariamente antes de hace 8,3 ka. Por el contrario, los sedimentos arenosos que los cubren sin rasgos de edafogénesis se depositaron posteriormente debido a una aridez creciente hasta hace 6,6 ka. Los rasgos micromorfológicos de los sedimentos arenosos están caracterizados por una

  10. Pangaean climate during the Early Jurassic: GCM simulations and the sedimentary record of paleoclimate

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, M.A. [Columbia Univ., Palisades, NY (United States); Rind, D.; Ruedy, R. [Goddard Institute for Space Studies, New York, NY (United States)

    1992-05-01

    Results from new simulations of the Early Jurassic climate show that increased ocean heat transport may have been the primary force generating warmer climates during the past 180 m.y. The simulations, conducted using the general circulation model (GCM) at the Goddard Institute for Space Studies, include realistic representations of paleocontinental distribution, topography, epeiric seas, and vegetation, in order to facilitate comparisons between model results and paleoclimate data. three major features of the simulated Early Jurassic climate include the following. (1) A global warming, compared to the present, of 5 {degrees}C to 10 {degrees}C, with temperature increases at high latitudes five times this global average. Average summer temperatures exceed 35 {degrees}C in low-latitude regions of western Pangaea where eolian sandstones testify to the presence of vast deserts. (2) Simulated precipitation and evaporation patterns agree closely with the moisture distribution interpreted from evaporites, and coal deposits. High rainfall rates are associated primarily with monsoons that originate over the warm Tethys Ocean. Unlike the {open_quotes}megamonsoons{close_quotes} proposed in previous studies, these systems are found to be associated with localized pressure cells whose positions are controlled by topography and coastal geography. (3) Decreases in planetary albedo, occurring because of reductions in sea ice, snow cover, and low clouds, and increases in atmospheric water vapor are the positive climate feedbacks that amplify the global warming. Similar to other Mesozoic climate simulations, our model finds that large seasonal temperature fluctuations occurred over mid- and high-latitude continental interiors, refuting paleoclimate evidence that suggests more equable conditions. 101 refs., 9 figs., 3 tabs.

  11. Environmental Management Audit: Southwestern Power Administration (Southwestern)

    International Nuclear Information System (INIS)

    1993-03-01

    This report documents the results of the Environmental Management Audit completed for the Southwestern Power Administration. During this Audit, activities and records were reviewed and personnel interviewed. The onsite portion of the Southwestern Audit was conducted from November 30 through December 11, 1992, by the US Department of Energy's Office of Environmental Audit (EH-24). EH-24 carries out independent assessments of Department of Energy (DOE) facilities and activities as part of the Assistant Secretary's Environmental Audit Program. This program is designed to evaluate the status of DOE facilities/activities regarding compliance with laws, regulations, DOE Orders, formal written procedures, compliance agreements, and Best Management Practices (BMPs). This internal oversight function plays an important role in improving the compliance status of DOE operations. The Environmental Management Audit stresses DOE's policy that it is the responsibility of line management to conduct operations in an environmentally sound and safe manner. The Environmental Management Audit focuses on management systems and programs, whereas the Environmental Baseline Audit conducted in March 1991 focused on specific compliance issues. The scope of the Southwestern Environmental Management Audit included a review of all systems and functions necessary for effective environmental management. Specific areas of review included: Organizational Structure; Environmental Commitment; Environmental Protection Programs; Formality of Environmental Programs; Internal and External Communication; Staff Resources, Training, and Development; and Program Evaluation, Reporting, and Corrective Action

  12. Biological effects of desert dust in respiratory epithelial cells and a murine model.

    Science.gov (United States)

    Abstract As a result of the challenge of recent dust storms to public health, we tested the postulate that desert dust collected in the southwestern United States could impact a biological effect in respiratory epithelial cells and an animal model. Two samples of surface sedime...

  13. Community ecology, climate change and ecohydrology in desert grassland and shrubland

    Science.gov (United States)

    Mathew Daniel Petrie

    2014-01-01

    This dissertation explores the climate, ecology and hydrology of Chihuahuan Desert ecosystems in the context of global climate change. In coming decades, the southwestern United States is projected to experience greater temperature-driven aridity, possible small decreases in annual precipitation, and a later onset of summer monsoon rainfall. These changes may have...

  14. Tracking variable sedimentation rates in orbitally forced paleoclimate proxy series

    Science.gov (United States)

    Li, M.; Kump, L. R.; Hinnov, L.

    2017-12-01

    This study addresses two fundamental issues in cyclostratigraphy: quantitative testing of orbital forcing in cyclic sedimentary sequences and tracking variable sedimentation rates. The methodology proposed here addresses these issues as an inverse problem, and estimates the product-moment correlation coefficient between the frequency spectra of orbital solutions and paleoclimate proxy series over a range of "test" sedimentation rates. It is inspired by the ASM method (1). The number of orbital parameters involved in the estimation is also considered. The method relies on the hypothesis that orbital forcing had a significant impact on the paleoclimate proxy variations, and thus is also tested. The null hypothesis of no astronomical forcing is evaluated using the Beta distribution, for which the shape parameters are estimated using a Monte Carlo simulation approach. We introduce a metric to estimate the most likely sedimentation rate using the product-moment correlation coefficient, H0 significance level, and the number of contributing orbital parameters, i.e., the CHO value. The CHO metric is applied with a sliding window to track variable sedimentation rates along the paleoclimate proxy series. Two forward models with uniform and variable sedimentation rates are evaluated to demonstrate the robustness of the method. The CHO method is applied to the classical Late Triassic Newark depth rank series; the estimated sedimentation rates match closely with previously published sedimentation rates and provide a more highly time-resolved estimate (2,3). References: (1) Meyers, S.R., Sageman, B.B., Amer. J. Sci., 307, 773-792, 2007; (2) Kent, D.V., Olsen, P.E., Muttoni, G., Earth-Sci. Rev.166, 153-180, 2017; (3) Li, M., Zhang, Y., Huang, C., Ogg, J., Hinnov, L., Wang, Y., Zou, Z., Li, L., 2017. Earth Plant. Sc. Lett. doi:10.1016/j.epsl.2017.07.015

  15. The Brazilian Northeastern paleoclimate according to the isotope hydrology

    International Nuclear Information System (INIS)

    Frischkorn, Horst; Santiago, Maria Marlucia Freitas

    1992-01-01

    This work interprets measures in deep well waters of the Serra Grande aquifer from the Piaui State. It uses the temperature and quantity effects on the oxygen isotopic composition in the pluvial water, together the noble gases analysis dissolved in water and 14 C dating in the bicarbonates to establish a time scale, aiming to reconstruct the Brazil Northeastern region paleoclimate at the Pleistocene final era, as well as to elucidate the hydric resources formation conditions (that date from this epoch) in the deep aquifers of the region sedimentary basins

  16. Complex Empiricism and the Quantification of Uncertainty in Paleoclimate Reconstructions

    Science.gov (United States)

    Brumble, K. C.

    2014-12-01

    Because the global climate cannot be observed directly, and because of vast and noisy data sets, climate science is a rich field to study how computational statistics informs what it means to do empirical science. Traditionally held virtues of empirical science and empirical methods like reproducibility, independence, and straightforward observation are complicated by representational choices involved in statistical modeling and data handling. Examining how climate reconstructions instantiate complicated empirical relationships between model, data, and predictions reveals that the path from data to prediction does not match traditional conceptions of empirical inference either. Rather, the empirical inferences involved are "complex" in that they require articulation of a good deal of statistical processing wherein assumptions are adopted and representational decisions made, often in the face of substantial uncertainties. Proxy reconstructions are both statistical and paleoclimate science activities aimed at using a variety of proxies to reconstruct past climate behavior. Paleoclimate proxy reconstructions also involve complex data handling and statistical refinement, leading to the current emphasis in the field on the quantification of uncertainty in reconstructions. In this presentation I explore how the processing needed for the correlation of diverse, large, and messy data sets necessitate the explicit quantification of the uncertainties stemming from wrangling proxies into manageable suites. I also address how semi-empirical pseudo-proxy methods allow for the exploration of signal detection in data sets, and as intermediary steps for statistical experimentation.

  17. Lut Desert, Iran

    Science.gov (United States)

    1981-01-01

    Iran is a large country with several desert regions. In the Dasht-E-Lut (Lut Desert) (30.5N, 58.5E) an area known as Namak-Zar, about 100 miles east of the city of Kerman, is at the center of this photograph. Some of the world's most prominent Yardangs (very long, parallel ridges and depressions) have been wind eroded in these desert dry lake bed sediments. At the left of the photo is a large field of sand dunes at right angles to the wind.

  18. Fungal genomes that influence basic physiological processes of black grama and fourwing saltbush in arid southwestern rangelands

    Science.gov (United States)

    J.R. Barrow; M. Lucero; P. Osuna-Avila; I. Reyes-Vera; R.E. Aaltonen

    2007-01-01

    Symbiotic fungi confer multiple benefits such as enhanced photosynthetic rates and drought tolerance in host plants. Shrubs and grasses of southwestern deserts are colonized by symbiotic fungi that cannot be removed by conventional sterilization methods. These fungi were extensively studied in Bouteloua eriopoda (Torr.) Torr. and Atriplex...

  19. Desert Pavement Studies

    National Research Council Canada - National Science Library

    Haff, Peter

    2003-01-01

    Combining plan view information from aerial photography showing details of stream channels on desert pavement surfaces with process-based erosion models, a high-resolution, synthetic topography DEM...

  20. Desert Pavement Studies

    National Research Council Canada - National Science Library

    Haff, P

    2003-01-01

    Combining plan view information from aerial photography showing details of stream channels on desert pavement surfaces with process-based erosion models, a high-resolution, "synthetic topography" DEM...

  1. Vertisols (as paleosols) with its related gigants land cracks as a disaster in central Iran deserts

    International Nuclear Information System (INIS)

    Akhavan Ghalibaf, M.; Alhoseini Almodarresi, B. B. S.

    2009-01-01

    This paper discuses the genesis of land cracks and land depression as one of the clayey desert futures in Central Iran. The origin of this future has been issued after downfall of ground water pressure. The clay mineralogy showed that the swelling clays of smectite groups (like as beidellite) as vertisols can be mainspring for this limitation future in Central Iran. It concluded that pedogenesis in the paleoclimates was effective to form these smectite groups of minerals in paleosoils of Yarzd, Central Iran. (Author) 6 refs.

  2. Minerals in deserts

    International Nuclear Information System (INIS)

    Smith, G.I.

    1982-01-01

    Almost any kind of mineral deposit can occur in desert areas, and the lack of vegetation and soil cover makes finding them easier. Some kinds of deposits, though, are more likely to occur in deserts than elsewhere. Some of these result from processes genetically related to the present desert climate that improved lower grade deposits of ore. One such process, termed secondary enrichment, is most effective in areas with deep water tables, and many low-grade copper, silver, and uranium deposits have been converted into mineable ore by the downward migration and redeposition of soluble metals. In a desert terrane, placer processes are effective whenever running water flowing over steep slopes erodes outcropping ore bodies and transports and concentrates the heavier ore minerals at lower levels, thus converting low-grade or hard-to-mine bedrock deposits into economically workable concentrations. Other kinds of deposits are better preserved in deserts because the lower rainfall at the surface, and the lower volume of flow and the greater depths to groundwater, result in less destruction of soluble ores; deposits of salines and phosphates are the most notable ores affected by these factors. Still other ore deposits are created as a consequence of the arid climate, mostly because the high evaporation rates operating on standing bodies of water produce brines that can lead directly to concentrations of salts and indirectly to secondary minerals, such as zeolites, that are produced by reaction of silicate minerals with saline waters

  3. Aircraft and satellite remote sensing of desert soils and landscapes

    Science.gov (United States)

    Petersen, G. W.; Connors, K. F.; Miller, D. A.; Day, R. L.; Gardner, T. W.

    1987-01-01

    Remote sensing data on desert soils and landscapes, obtained by the Landsat TM, Heat Capacity Mapping Mission (HCMM), Simulated SPOT, and Thermal IR Multispectral Scanner (TIMS) aboard an aircraft, are discussed together with the analytical techniques used in the studies. The TM data for southwestern Nevada were used to discriminate among the alluvial fan deposits with different degrees of desert pavement and varnish, and different vegetation cover. Thermal-IR data acquired from the HCMM satellite were used to map the spatial distribution of diurnal surface temperatures and to estimate mean annual soil temperatures in central Utah. Simulated SPOT data for northwestern New Mexico identified geomorphic features, such as differences in eolian sand cover and fluvial incision, while the TIMS data depicted surface geologic features of the Saline Valley in California.

  4. Geology of wadi atalla - el missikat area, eastern desert, egypt.

    OpenAIRE

    El Kassas, I. A. [ابراهيم علي القصاص; Bakhit, F. S.

    1989-01-01

    Wadi Atalla-El Missikat area covers about 2,000 Km2 in the central Eastern Desert of Egypt, between latitudes 26° 10' and 26° 40' N, and longitudes 33° 15' and 33° 40' E. The area is mainly formed of basement complex except its extreme south-western corner where it is covered by foreland sediments of Nubian sandstone. The area is structurally complicated where it has been subjected to various stages of successive tectonic movements since the Precambrian times. The basement complex in the stud...

  5. Radon and 'King Solomon's Miners'. Faynan Orefield, Jordanian Desert

    International Nuclear Information System (INIS)

    Grattan, J.P.; Gillmore, G.K.; Gilbertson, D.D.; Pyatt, F.B.; Hunt, C.O.; McLaren, S.J.; Phillips, P.S.; Denman, A.

    2004-01-01

    Concentrations of 222 Rn were measured in ancient copper mines which exploited the Faynan Orefield in the South-Western Jordanian Desert. The concentrations of radon gas detected indicate that the ancient metal workers would have been exposed to a significant health risk and indicate that any future attempt to exploit the copper ores must deal with the hazard identified. Seasonal variations in radon concentrations are noted and these are linked to the ventilation of the mines. These modern data are used to explore the differential exposure to radon and the health of ancient mining communities

  6. How desert varnish forms?

    Science.gov (United States)

    Perry, Randall S.; Kolb, Vera M.; Lynne, Bridget Y.; Sephton, Mark A.; Mcloughlin, Nicola; Engel, Michael H.; Olendzenski, Lorraine; Brasier, Martin; Staley, James T., Jr.

    2005-09-01

    Desert varnish is a black, manganese-rich rock coating that is widespread on Earth. The mechanism underlying its formation, however, has remained unresolved. We present here new data and an associated model for how desert varnish forms, which substantively challenges previously accepted models. We tested both inorganic processes (e.g. clays and oxides cementing coatings) and microbial methods of formation. Techniques used in this preliminary study include SEM-EDAX with backscatter, HRTEM of focused ion beam prepared (FIB) wafers and several other methods including XRPD, Raman spectroscopy, XPS and Tof-SIMS. The only hypothesis capable of explaining a high water content, the presence of organic compounds, an amorphous silica phase (opal-A) and lesser quantities of clays than previously reported, is a mechanism involving the mobilization and redistribution of silica. The discovery of silica in desert varnish suggests labile organics are preserved by interaction with condensing silicic acid. Organisms are not needed for desert varnish formation but Bacteria, Archaea, Eukarya, and other organic compounds are passively incorporated and preserved as organominerals. The rock coatings thus provide useful records of past environments on Earth and possibly other planets. Additionally this model also helps to explain the origin of key varnish and rock glaze features, including their hardness, the nature of the "glue" that binds heterogeneous components together, its layered botryoidal morphology, and its slow rate of formation.

  7. GOPHERUS AGASSIZII (Desert Tortoise)

    International Nuclear Information System (INIS)

    JAMES L. BOONE, DANNY L. RAKESTRAW, AND KURT R. RAUTENSTRAUCH

    1997-01-01

    GOPHERLTS AGAISSIZII (Desert Tortoise). Predation. A variety of predators, most notably coyotes (Canis Iatrans) and Common Ravens (Corvis corau) have been reported to prey on hatchling desert tortoises (Emst et al. 1994). Turtles of the United States and Canada (Smithsonian Institution Press, Washington, D.C. 578 pp.). Here, we report an observation of a hatchling tortoise, fitted with a radiotransmitter, that was preyed upon by native fire ants (Solenopsis sp.) in the eastern Mojave Desert at Yucca Mountain, Nevada (36 degrees 50 minutes N, 116 degree 25 minutes E). On 8/27/94, tortoise No.9315 (carapace length = 45 mm, age = 5 d) was found alive with eyes, chin, and parts of the head and legs being eaten by ants. The tortoise was alive, but lethargic, and responded little when touched. Eight of 74 other radiomarked hatchlings monitored at Yucca Mountain during 1992-1994 were found dead with fire ants on their carcass 3-7 days after the hatchlings emerged from their nests. It is not known whether those tortoises were killed by ants or were being scavenged when found. While imported fire ants (S. invicta) have long been known to kill hatchling gopher tortoises (G. polyphemus; Mount 1981. J. Alabama Acad. Sci. 52: 71-78), native fire ants have previously not been implicated as predators of desert tortoises. However, only 1 of 75 (or at worst 9 of 75) was killed by fire ants, suggesting that although fire ants do kill hatchlings, they were not important predators on desert tortoises during this study. Tortoise specimens were deposited at the University of California at Berkeley

  8. The paleoclimate of the Kazanian (early Late Permian) world

    Energy Technology Data Exchange (ETDEWEB)

    Moore, G.T. (Chevron Oil Field Research Co., La Habra, CA (USA)); Peoples, C.J. (Texas A and M Univ., College Station (USA))

    1990-05-01

    The Kazanian (early Late Permian, 258-253 m.y.) marked the onset of a unique interval in the Phanerozoic, distinguished by a classic end-member case of continental assembly, the megacontinent Pangaea. Compilation of biostratigraphic and lithofacies data indicate a warm, extensively arid world, largely ice free, and characterized by the onset of atmospheric conditions that were exceedingly stressful to the biosphere, the worst of the eon. Using Chevron's version of the Community Climate model, the authors report here on two Kazanian paleoclimate seasonal simulations, one using 200 ppm CO{sub 2} and the other with 2,000 ppm CO{sub 2}. The authors consider the knowledge of plate assembly back to the Permian accurate enough to allow employment of a seasonal model. Simulation of a warmer Earth with an elevated greenhouse effect (modeled as CO{sub 2}) fits the observed geology and isotope signals. The increased CO{sub 2} experiment warmed the entire planet with the greatest increases north of 50{degree} latitude and least changes in the tropics. The warming caused the poleward retreat of sea ice in both hemispheres. Precipitation and evaporation increased, but runoff was confined to areas of very intense rainfall. Monsoons are limited to the southern hemisphere, associated with the western Tethys sea and the eastern equatorial Panthalassa ocean. Extreme southeastern Pangaea (northern Australia) was a focus of precipitation throughout the year. Precipitation occurred in the higher latitudes (50-55{degree}) on the western coast, of Pangaea where storm tracks make landfall. High evaporation rates characterized the restricted Permian (US), Zechstein, and Perm (Soviet Union) basins, a time of evaporite, deposition. Interior Pangaea at middle to high latitudes endured frigid winters ({minus}40{degree}C) and torrid summers (60{degree}C).

  9. Paleoclimate records at high latitude in Arctic during the Paleogene

    Science.gov (United States)

    Salpin, Marie; Schnyder, Johann; Baudin, François; Suan, Guillaume; Labrousse, Loïc; Popescu, Speranta; Suc, Jean-Pierre

    2015-04-01

    Paleoclimate records at high latitude in Arctic during the Paleogene SALPIN Marie1,2, SCHNYDER Johann1,2, BAUDIN François1,2, SUAN Guillaume3, LABROUSSE Loïc1,2, POPESCU Speranta4, SUC Jean-Pierre1,4 1: Sorbonne Universités, UPMC Univ Paris 06, UMR 7193, Institut des Sciences de la Terre Paris (iSTeP), F 75005, Paris, France 2: CNRS, UMR 7193, Institut des Sciences de la Terre Paris (iSTeP), F 75005 Paris, France 3: UCB Lyon 1, UMR 5276, LGLTPE, 69622 Villeurbanne Cedex, France 4: GEOBIOSTRATDATA.CONSULTING, 385 Route du Mas Rillier 69140 Rillieux la Pape, France The Paleogene is a period of important variations of the Earth climate system either in warming or cooling. The climatic optima of the Paleogene have been recognized both in continental and marine environment. This study focus on high latitudes of the northern hemisphere, in the Arctic Basin. The basin has had an influence on the Cenozoic global climate change according to its polar position. Is there a specific behaviour of the Arctic Basin with respect to global climatic stimuli? Are there possible mechanisms of coupling/decoupling of its dynamics with respect to the global ocean? To answer these questions a unique collection of sedimentary series of Paleogene age interval has been assembled from the Laurentian margin in Northern Yukon (Canada) and from the Siberian margin (New Siberian Islands). Selected continental successions of Paleocene-Eocene age were used to study the response of the Arctic system to known global events, e.g. the climatic optima of the Paleogene (the so-called PETM, ETM2 or the Azolla events). Two sections of Paleocene-Eocene age were sampled near the Mackenzie delta, the so-called Coal Mine (CoMi) and Caribou Hills (CaH) sections. The aim of the study is to precise the climatic fluctuations and to characterise the source rock potential of the basin, eventually linked to the warming events. This study is based on data of multi-proxy analyses: mineralogy on bulk and clay

  10. Constraining Lipid Biomarker Paleoclimate Proxies in a Small Arctic Watershed

    Science.gov (United States)

    Dion-Kirschner, H.; McFarlin, J. M.; Axford, Y.; Osburn, M. R.

    2017-12-01

    Arctic amplification of climate change renders high-latitude environments unusually sensitive to changes in climatic conditions (Serreze and Barry, 2011). Lipid biomarkers, and their hydrogen and carbon isotopic compositions, can yield valuable paleoclimatic and paleoecological information. However, many variables affect the production and preservation of lipids and their constituent isotopes, including precipitation, plant growth conditions, biosynthesis mechanisms, and sediment depositional processes (Sachse et al., 2012). These variables are particularly poorly constrained for high-latitude environments, where trees are sparse or not present, and plants grow under continuous summer light and cool temperatures during a short growing season. Here we present a source-to-sink study of a single watershed from the Kangerlussuaq region of southwest Greenland. Our analytes from in and around `Little Sugarloaf Lake' (LSL) include terrestrial and aquatic plants, plankton, modern lake water, surface sediments, and a sediment core. This diverse sample set allows us to fulfill three goals: 1) We evaluate the production of lipids and isotopic signatures in the modern watershed in comparison to modern climate. Our data exhibit genus-level trends in leaf wax production and isotopic composition, and help clarify the difference between terrestrial and aquatic signals. 2) We evaluate the surface sediment of LSL to determine how lipid biomarkers from the watershed are incorporated into sediments. We constrain the relative contributions of terrestrial plants, aquatic plants, and other aquatic organisms to the sediment in this watershed. 3) We apply this modern source-to-sink calibration to the analysis of a 65 cm sediment core record. Our core is organic-rich, and relatively high deposition rates allow us to reconstruct paleoenvironmental changes with high resolution. Our work will help determine the veracity of these common paleoclimate proxies, specifically for research in

  11. Tales from the Paleoclimate Underground: Lessons Learned from Reconstructing Extreme Events

    Science.gov (United States)

    Frappier, A. E.

    2017-12-01

    Tracing patterns of paleoclimate extremes over the past two millennia is becoming ever more important in the effort to understand and predict costly weather hazards and their varied societal impacts. I present three paleoclimate vignettes from the past ten years of different paleotempestology projects I have worked on closely, illustrating our collective challenges and productive pathways in reconstructing rainfall extremes: temporal, spatial, and combining information from disparate proxies. Finally, I aim to share new results from modeling multiple extremes and hazards in Yucatan, a climate change hotspot.

  12. Controls on the variability of net infiltration to desert sandstone

    Science.gov (United States)

    Heilweil, Victor M.; McKinney, Tim S.; Zhdanov, Michael S.; Watt, Dennis E.

    2007-01-01

    As populations grow in arid climates and desert bedrock aquifers are increasingly targeted for future development, understanding and quantifying the spatial variability of net infiltration becomes critically important for accurately inventorying water resources and mapping contamination vulnerability. This paper presents a conceptual model of net infiltration to desert sandstone and then develops an empirical equation for its spatial quantification at the watershed scale using linear least squares inversion methods for evaluating controlling parameters (independent variables) based on estimated net infiltration rates (dependent variables). Net infiltration rates used for this regression analysis were calculated from environmental tracers in boreholes and more than 3000 linear meters of vadose zone excavations in an upland basin in southwestern Utah underlain by Navajo sandstone. Soil coarseness, distance to upgradient outcrop, and topographic slope were shown to be the primary physical parameters controlling the spatial variability of net infiltration. Although the method should be transferable to other desert sandstone settings for determining the relative spatial distribution of net infiltration, further study is needed to evaluate the effects of other potential parameters such as slope aspect, outcrop parameters, and climate on absolute net infiltration rates.

  13. Population, desert expanding.

    Science.gov (United States)

    1992-01-01

    The conditions of desert expansion in the Sahara are highlighted. On the southern border the desert is growing at a rate of 3-6 miles/year. This growth is encroaching on arable land in Ethiopia and Mauritania. The region loses up to 28,000 sq miles/year of farmland. 33% of Africa's fertile land is threatened. Land-use patterns are responsible for the deterioration of the soil. Traditional practices are not effective because the practices are not suitable for permanent farming. Farmers also have stopped environmentally sound practices such as letting the fields remain fallow in order to renew soil fertility. Nomads overgraze areas before moving on. A recent study by the World Bank's Africa Region Office was released; the report details some of the links between rapid population growth, poor agricultural performance, and environmental degradation. Soil conditions are such that valuable topsoil is blow away by the wind because the layer is too thin. Vegetation at the desert's edge is used for cooking purposes or for heating fuel. Tropical and savannah areas are depleted when tree replacement is inadequate. Only 9 trees are planted for every 100 removed. The report emphasized the role of women and children in contributing to population pressure by increased fertility. Women's work load is heavy and children are a help in alleviating some of the burden of domestic and agricultural work. There is hope in meeting demographic, agricultural, food security, and environmental objectives over the next 30 years if the needs of women are met. The needs include access to education for young women, lessening the work loads of women, and decreasing child mortality through improved health care and access to safe water.

  14. Physiological adaptation in desert birds

    NARCIS (Netherlands)

    Williams, JB; Tieleman, BI; Williams, Joseph B.

    We call into question the idea that birds have not evolved unique physiological adaptations to desert environments. The rate at which desert larks metabolize energy is lower than in mesic species within the same family, and this lower rate of living translates into a lower overall energy requirement

  15. A Taxonomic Reduced-Space Pollen Model for Paleoclimate Reconstruction

    Science.gov (United States)

    Wahl, E. R.; Schoelzel, C.

    2010-12-01

    Paleoenvironmental reconstruction from fossil pollen often attempts to take advantage of the rich taxonomic diversity in such data. Here, a taxonomically "reduced-space" reconstruction model is explored that would be parsimonious in introducing parameters needing to be estimated within a Bayesian Hierarchical Modeling context. This work involves a refinement of the traditional pollen ratio method. This method is useful when one (or a few) dominant pollen type(s) in a region have a strong positive correlation with a climate variable of interest and another (or a few) dominant pollen type(s) have a strong negative correlation. When, e.g., counts of pollen taxa a and b (r >0) are combined with pollen types c and d (r logistic generalized linear model (GLM). The GLM can readily model this relationship in the forward form, pollen = g(climate), which is more physically realistic than inverse models often used in paleoclimate reconstruction [climate = f(pollen)]. The specification of the model is: rnum Bin(n,p), where E(r|T) = p = exp(η)/[1+exp(η)], and η = α + β(T); r is the pollen ratio formed as above, rnum is the ratio numerator, n is the ratio denominator (i.e., the sum of pollen counts), the denominator-specific count is (n - rnum), and T is the temperature at each site corresponding to a specific value of r. Ecological and empirical screening identified the model (Spruce+Birch) / (Spruce+Birch+Oak+Hickory) for use in temperate eastern N. America. α and β were estimated using both "traditional" and Bayesian GLM algorithms (in R). Although it includes only four pollen types, the ratio model yields more explained variation ( 80%) in the pollen-temperature relationship of the study region than a 64-taxon modern analog technique (MAT). Thus, the new pollen ratio method represents an information-rich, reduced space data model that can be efficiently employed in a BHM framework. The ratio model can directly reconstruct past temperature by solving the GLM equations

  16. Supersymmetry without the Desert

    International Nuclear Information System (INIS)

    Nomura, Yasunori; Poland, David

    2006-01-01

    Naturalness of electroweak symmetry breaking in weak scale supersymmetric theories may suggest the absence of the conventional supersymmetric desert. We present a simple, realistic framework for supersymmetry in which (most of) the virtues of the supersymmetric desert are naturally reproduced without having a large energy interval above the weak scale. The successful supersymmetric prediction for the low-energy gauge couplings is reproduced due to a gauged R symmetry present in the effective theory at the weak scale. The observable sector superpotential naturally takes the form of the next-to-minimal supersymmetric standard model, but without being subject to the Landau pole constraints up to the conventional unification scale. Supersymmetry breaking masses are generated by the F-term and D-term VEVs of singlet and U(1) R gauge fields, as well as by anomaly mediation, at a scale not far above the weak scale. We study the resulting pattern of supersymmetry breaking masses in detail, and find that it can be quite distinct. We construct classes of explicit models within this framework, based on higher dimensional unified theories with TeV-sized extra dimensions. A similar model based on a non-R symmetry is also presented. These models have a rich phenomenology at the TeV scale, and allow for detailed analyses of, e.g., electroweak symmetry breaking

  17. AQUIFER IN AJAOKUTA, SOUTHWESTERN NIGERIA

    African Journals Online (AJOL)

    2005-03-08

    Mar 8, 2005 ... To establish the feasibility of water supply in a basement complex area ofAjaokuta, Southwestern Nigeria, pumping test results were used to investigate the storage properties and groundwater potential of the aquifer. The aquifer system consists of weathered and weathered/fractured zone of decomposed ...

  18. PaleoClim: new datasets to quantify the impact of past climate changes on modern biodiversity

    Science.gov (United States)

    Hill, D. J.; Brown, J. T.; Carnaval, A. C.; Haywood, A. M.

    2017-12-01

    Palaeoclimate history is an important driver of modern patterns of biodiversity and many ecological modelling studies have shown the predictive power of palaeoclimate information. However, a major limiting factor to such studies is the availability of global palaeoclimate reconstructions in the relevant bioclim layers. The primary source of such fields is from climate model simulations, which are currently limited to the key PMIP (Paleoclimate Modelling Intercomparison Project) intervals of the mid-Holocene (6ka), the Last Glacial Maximum (21ka) and the Last Interglaciation (130ka). The PaleoClim project will significantly increase the availability of pre-processed palaeoclimate bioclim information and provide a new platform for accessing the information. The first new PaleoClim time period will be the mid-Pliocene Warm Period (3Ma). This is the last period of sustained globally warmer than modern climate in Earth history and represents the last global warmth before the cooling into the Pleistocene ice ages. Being 3 million years ago this represents a significant lengthening of the time range of available bioclim layers and the first time these have been available over evolutionary timescales. PaleoClim will also greatly expand the available Pleistocene time periods, looking to both quantify the differences between the late Pleistocene interglacial periods and understand the role of orbital changes in modulating tropical precipitation and driving modern biodiversity patterns.

  19. Utilization of paleoclimate results to validate projections of a future greenhouse warming

    International Nuclear Information System (INIS)

    Crowley, T.J.

    1990-01-01

    Paleoclimate data provide a rich source of information for testing projections of future greenhouse trends. This paper summarizes the present state-of-the-art as to assessments of two important climate problems. (1) Validation of climate models - The same climate models that have been used to make greenhouse forecasts have also been used for paleoclimate simulations. Comparisons of model results and observations indicate some impressive successes but also some cases where there are significant divergences between models and observations. However, special conditions associated with the impressive successes could lead to a false confidence in the models; disagreements are a topic of greater concern. It remains to be determined whether the disagreements are due to model limitations or uncertainties in geologic data. (2) Role of CO 2 as a significant climate feedback: Paleoclimate studies indicate that the climate system is generally more sensitive than our ability to model it. Addition or subtraction of CO 2 leads to a closer agreement between models and observations. In this respect paleoclimate results in general support the conclusion that CO 2 is an important climate feedback, with the magnitude of the feedback approximately comparable to the sensitivity of present climate models. If the CO 2 projections are correct, comparison of the future warming with past warm periods indicate that there may be no geologic analogs for a future warming; the future greenhouse climate may represent a unique climate realization in earth history

  20. Livestock grazing and the desert tortoise in the Mojave Desert

    Science.gov (United States)

    Oldemeyer, John L.

    1994-01-01

    A large part of the Mojave Desert is not in pristine condition, and some current conditions can be related to past grazing-management practices. No information could be found on densities of the desert tortoise (Gopherus agassizii) or on vegetative conditions of areas that had not been grazed to allow managers a comparison of range conditions with data on tortoises. Experimental information to assess the effect of livestock grazing on tortoises is lacking, and researchers have not yet examined whether the forage that remains after grazing is sufficient to meet the nutritional needs of desert tortoises.

  1. Why Drill More than One Ice Core? Paleoclimate Reconstruction along a Vertical Transect in the Saint Elias Mountains

    Science.gov (United States)

    Wake, C. P.; Yalcin, K.; Kreutz, K. J.; Mayewski, P. A.; Fisher, D.; Holdsworth, G.

    2004-05-01

    The Arctic represents one of the key regions on Earth in our efforts to document and understand global change. The St. Elias mountain range in the southwestern Yukon Territory has recently been the focus of an international ice core research.. The broad elevational extent of snow accumulation zones in this region (ranging from 2500 to 5300 m asl) allows for the detailed investigation of environmental change extending from the planetary boundary layer through to the free troposphere via the collection and analysis of ice cores from different elevations. Multi-parameter, high resolution glaciochemical records are currently available from the Northwest Col on Mt. Logan (5340 m asl, 103 m deep; 270 year record;) and from three cores recovered from the Eclipse Icefield (3107 m asl) in 1996 (160 m deep; 100 year record) and in 2002 (345 m and 140 m deep). Snow accumulation rates at Eclipse are about 5 times larger than the summit average of 0.30 m water equivalent. Despite their close proximity, the climate signals recorded on the summit of Mt. Logan also differ from those at Eclipse. For example, while the Mt. Logan record shows no increase in sulfate or nitrate deposition over the past 100 years, all three Eclipse cores shows a clear increase in nitrate and sulfate deposition beginning in the late 1940s due to an increase in anthropogenic emissions in Eurasia during this time period. Over the last century, the sulfate time-series from Eclipse records from 32 discrete volcanic events, primarily from Alaskan, Aleutian, or Kamchatkan eruptions, while the summit site only records 8 volcanic events. The Eclipse summer d18O record displays a significant positive relationship with summer temperatures at both coastal and interior Alaskan sites, while the Mt. Logan d18O time-series does not correlate well with instrumental temperature records or most circum-Arctic paleoclimate records. Conversely, the summit ice core accumulation time-series strongly correlates with

  2. Remote Sensing Field Guide - Desert

    Science.gov (United States)

    1991-09-01

    experienced boatmen. Most river water, even in deserts, contains Giardia micro -organisms that can cause serious diarrhea. Sich water should be boiled...water. The solutes and suspended micro -matter can be moved up and down by an oscillating water table and redeposited or precipitated at differ- ent...McCauley, U.S. Geological Survey, Desert Studies Group, Flagstaff, AZ, Nov 1973. B. Servicio Aerofotografia Nacional del Peru (on back). / ...... CONN:MFI

  3. Southwestern Power Administration Update, October- December 2004

    Energy Technology Data Exchange (ETDEWEB)

    None

    2004-12-01

    On October 29, 2004, Southwestern and Southwest Power Pool, Inc. (SPP) reached agreement on interim arrangements to be implemented after the October 31, 2004, expiration of the membership agreement between the two parties. According to Jim McDonald, Director of Southwestern’s Division of Customer Service, the interim agreement forged between Southwestern and SPP seeks to minimize impacts to SPP as well as to Southwestern and its customers while Southwestern and SPP work on a seams/coordination agreement to succeed the expired membership agreement.

  4. Synthesizing late Holocene paleoclimate reconstructions: Lessons learned, common challenges, and implications for future research

    Science.gov (United States)

    Rodysill, J. R.

    2017-12-01

    Proxy-based reconstructions provide vital information for developing histories of environmental and climate changes. Networks of spatiotemporal paleoclimate information are powerful tools for understanding dynamical processes within the global climate system and improving model-based predictions of the patterns and magnitudes of climate changes at local- to global-scales. Compiling individual paleoclimate records and integrating reconstructed climate information in the context of an ensemble of multi-proxy records, which are fundamental for developing a spatiotemporal climate data network, are hindered by challenges related to data and information accessibility, chronological uncertainty, sampling resolution, climate proxy type, and differences between depositional environments. The U.S. Geological Survey (USGS) North American Holocene Climate Synthesis Working Group has been compiling and integrating multi-proxy paleoclimate data as part of an ongoing effort to synthesize Holocene climate records from North America. The USGS North American Holocene Climate Synthesis Working Group recently completed a late Holocene hydroclimate synthesis for the North American continent using several proxy types from a range of depositional environments, including lakes, wetlands, coastal marine, and cave speleothems. Using new age-depth relationships derived from the Bacon software package, we identified century-scale patterns of wetness and dryness for the past 2000 years with an age uncertainty-based confidence rating for each proxy record. Additionally, for highly-resolved North American lake sediment records, we computed average late Holocene sediment deposition rates and identified temporal trends in age uncertainty that are common to multiple lakes. This presentation addresses strengths and challenges of compiling and integrating data from different paleoclimate archives, with a particular focus on lake sediments, which may inform and guide future paleolimnological studies.

  5. Autogenic geomorphic processes determine the resolution and fidelity of terrestrial paleoclimate records

    OpenAIRE

    Foreman, Brady Z.; Straub, Kyle M.

    2017-01-01

    Terrestrial paleoclimate records rely on proxies hosted in alluvial strata whose beds are deposited by unsteady and nonlinear geomorphic processes. It is broadly assumed that this renders the resultant time series of terrestrial paleoclimatic variability noisy and incomplete. We evaluate this assumption using a model of oscillating climate and the precise topographic evolution of an experimental alluvial system. We find that geomorphic stochasticity can create aliasing in the time series and ...

  6. Chihuahuan Deserts Ecoregion: Chapter 27 in Status and trends of land change in the Western United States--1973 to 2000

    Science.gov (United States)

    Ruhlman, Jana; Gass, Leila; Middleton, Barry

    2012-01-01

    The Chihuahuan Desert is the largest of the North American deserts, extending from southern New Mexico and Texas deep into Mexico, with approximately 90 percent of its area falling south of the United States–Mexico border (Lowe, 1964, p. 24). The Chihuahuan Deserts Ecoregion covers approximately 174,472 km2 (67,364 mi2) within the United States, including much of west Texas, southern New Mexico, and a small portion of southeastern Arizona (Omernik, 1987; U.S. Environmental Protection Agency, 1997). The ecoregion is generally oriented from northwest to southeast, with the Madrean Archipelago Ecoregion to the west; the Arizona/New Mexico Mountains, Arizona/New Mexico Plateau, Southwestern Tablelands, and Western High Plains Ecoregions to the north; and the Edwards Plateau and Southern Texas Plains Ecoregions to the east (fig. 1).

  7. Middle and Late Pleistocene glaciations in the southwestern Pamir and their effects on topography [Topography of the SW Pamir shaped by middle-late Pleistocene glaciation

    International Nuclear Information System (INIS)

    Stübner, Konstanze; Grin, Elena; Hidy, Alan J.; Schaller, Mirjam; Gold, Ryan D.

    2017-01-01

    Glacial chronologies provide insight into the evolution of paleo-landscapes, paleoclimate, topography, and the erosion processes that shape mountain ranges. In the Pamir of Central Asia, glacial morphologies and deposits indicate extensive past glaciations, whose timing and extent remain poorly constrained. Geomorphic data and 15 new "1"0Be exposure ages from moraine boulders and roches moutonnées in the southwestern Pamir document multiple Pleistocene glacial stages. The oldest exposure ages, View the MathML source113 ± 10ka, underestimate the age of the earliest preserved glacial advance and imply that the modern relief of the southwestern Pamir (peaks at ~5000–6000 m a.s.l.; valleys at ~2000–3000 m a.s.l.) already existed in the late Middle Pleistocene. Younger exposure ages (~40–80 ka, ~30 ka) complement the existing Central Asian glacial chronology and reflect successively less extensive Late Pleistocene glaciations. The topography of the Pamir and the glacial chronologies suggest that, in the Middle Pleistocene, an ice cap or ice field occupied the eastern Pamir high-altitude plateau, whereas westward flowing valley glaciers incised the southwestern Pamir. Since the Late Pleistocene deglaciation, the rivers of the southwestern Pamir adjusted to the glacially shaped landscape. As a result, localized rapid fluvial incision and drainage network reorganization reflect the transient nature of the deglaciated landscape.

  8. Development of a North American paleoclimate pollen-based reconstruction database application

    Science.gov (United States)

    Ladd, Matthew; Mosher, Steven; Viau, Andre

    2013-04-01

    Recent efforts in synthesizing paleoclimate records across the globe has warranted an effort to standardize the different paleoclimate archives currently available in order to facilitate data-model comparisons and hence improve our estimates of future climate change. It is often the case that the methodology and programs make it challenging for other researchers to reproduce the results for a reconstruction, therefore there is a need for to standardize paleoclimate reconstruction databases in an application specific to proxy data. Here we present a methodology using the open source R language using North American pollen databases (e.g. NAPD, NEOTOMA) where this application can easily be used to perform new reconstructions and quickly analyze and output/plot the data. The application was developed to easily test methodological and spatial/temporal issues that might affect the reconstruction results. The application allows users to spend more time analyzing and interpreting results instead of on data management and processing. Some of the unique features of this R program are the two modules each with a menu making the user feel at ease with the program, the ability to use different pollen sums, select one of 70 climate variables available, substitute an appropriate modern climate dataset, a user-friendly regional target domain, temporal resolution criteria, linear interpolation and many other features for a thorough exploratory data analysis. The application program will be available for North American pollen-based reconstructions and eventually be made available as a package through the CRAN repository by late 2013.

  9. Reconstructing Late Holocene North Atlantic atmospheric circulation changes using functional paleoclimate networks

    Science.gov (United States)

    Franke, Jasper G.; Werner, Johannes P.; Donner, Reik V.

    2017-11-01

    Obtaining reliable reconstructions of long-term atmospheric circulation changes in the North Atlantic region presents a persistent challenge to contemporary paleoclimate research, which has been addressed by a multitude of recent studies. In order to contribute a novel methodological aspect to this active field, we apply here evolving functional network analysis, a recently developed tool for studying temporal changes of the spatial co-variability structure of the Earth's climate system, to a set of Late Holocene paleoclimate proxy records covering the last two millennia. The emerging patterns obtained by our analysis are related to long-term changes in the dominant mode of atmospheric circulation in the region, the North Atlantic Oscillation (NAO). By comparing the time-dependent inter-regional linkage structures of the obtained functional paleoclimate network representations to a recent multi-centennial NAO reconstruction, we identify co-variability between southern Greenland, Svalbard, and Fennoscandia as being indicative of a positive NAO phase, while connections from Greenland and Fennoscandia to central Europe are more pronounced during negative NAO phases. By drawing upon this correspondence, we use some key parameters of the evolving network structure to obtain a qualitative reconstruction of the NAO long-term variability over the entire Common Era (last 2000 years) using a linear regression model trained upon the existing shorter reconstruction.

  10. Fire Impacts on the Mojave Desert Ecosystem: Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Fenstermaker Lynn

    2012-01-01

    The Nevada National Security Site (NNSS) is located within the Mojave Desert, which is the driest region in North America. Precipitation on the NNSS varies from an annual average of 130 millimeters (mm; 5.1 inches) with a minimum of 47 mm (1.9 inches) and maximum of 328 mm (12.9 inches) over the past 15 year period to an annual average of 205 mm (8.1 inches) with an annual minimum of 89 mm (3.5 inches) and maximum of 391 mm (15.4 inches) for the same time period; for a Frenchman Flat location at 970 meters (m; 3182 feet) and a Pahute Mesa location at 1986 m (6516 feet), respectively. The combination of aridity and temperature extremes has resulted in sparsely vegetated basins (desert shrub plant communities) to moderately vegetated mountains (mixed coniferous forest plant communities); both plant density and precipitation increase with increasing elevation. Whereas some plant communities have evolved under fire regimes and are dependent upon fire for seed germination, plant communities within the Mojave Desert are not dependent on a fire regime and therefore are highly impacted by fire (Brown and Minnich, 1986; Brooks, 1999). As noted by Johansen (2003) natural range fires are not prevalent in the Mojave and Sonoran Deserts because there is not enough vegetation present (too many shrub interspaces) to sustain a fire. Fire research and hence publications addressing fires in the Southwestern United States (U.S.) have therefore focused on forest, shrub-steppe and grassland fires caused by both natural and anthropogenic ignition sources. In the last few decades, however, invasion of mid-elevation shrublands by non-native Bromus madritensis ssp. rubens and Bromus tectorum (Hunter, 1991) have been highly correlated with increased fire frequency (Brooks and Berry, 2006; Brooks and Matchett, 2006). Coupled with the impact of climate change, which has already been shown to be playing a role in increased forest fires (Westerling et al., 2006), it is likely that the fire

  11. Using of microvertebrate remains in reconstruction of late quaternary (Holocene paleoclimate, Eastern Iran

    Directory of Open Access Journals (Sweden)

    Mansour Aliabadian

    2015-09-01

    Full Text Available   Introduction   Study of quaternary microvertebrate remains in eastern Iran, according to a few of the sediments is very important. Reconstruction of quaternary climate in many parts of West and North West of Iran as the biggest karst state is possible, such as cave Kani Mikaiel (Hashemi et al. 2005, 2006, 2007ab, 2008 2010, Jangjoo et al . 2010, Yafteh cave (Otte et al. 2007, Hashemi et al. 2015. However, such studies were very poor in eastern and north-eastern Iran (Hashemi and darvish 2006 Hashemi et al. 2008, 2015. Investigation of taxonomic identification quantification and distribution of micromammals revealed that these remains are useful in paleontology and archaeological research, because their abundance is useful for paleobiostratigraphy and dating of continental sediments. The recent research is about reconstruction of paleoclimate in two archeological sites of Konar sandal (KS (Jiroft and Tapeh Naderi (TN (Mashhad based on the microvertebrate and especially Tatera indica species. In these sites we attempted to solve the palaeoenvironment condition by analysis of rodent remains which hold the greatest potential to monitoring of ecological parameters (Hoover et al. 1977 Getz 1961 Reig 1970 Merritt 1974. Combining of a rich network of data with using of morphological and morphometric methods reconstruction of paleoenvironment documentation and investigation of their relationship with the environment is the main result of this research .       Material & Methods   In both zooarchaeological samples which are composed of juveniles and young individual rodent, (KS, NISP=800 and TN, NISP=3 cranial and postcranial remains were sorted anatomically and washed with water. Dental pattern of mandible and maxillary tooth rows were drowns using a drawing tube connecting to a stereomicroscope (Olympus SZH-10. All recovered teeth fragments were measured based on the greatest dental length and width of the upper and lower jaw molars

  12. Using of microvertebrate remains in reconstruction of late quaternary (Holocene paleoclimate, Eastern Iran

    Directory of Open Access Journals (Sweden)

    Narges Hashemi

    2015-10-01

    Full Text Available Introduction   Study of quaternary microvertebrate remains in eastern Iran, according to a few of the sediments is very important. Reconstruction of quaternary climate in many parts of West and North West of Iran as the biggest karst state is possible, such as cave Kani Mikaiel (Hashemi et al. 2005, 2006, 2007a;b, 2008; 2010, Jangjoo et al . 2010, Yafteh cave (Otte et al. 2007, Hashemi et al. 2015. However, such studies were very poor in eastern and north-eastern Iran (Hashemi and darvish 2006; Hashemi et al. 2008, 2015. Investigation of taxonomic identification; quantification and distribution of micromammals revealed that these remains are useful in paleontology and archaeological research, because their abundance is useful for paleobiostratigraphy and dating of continental sediments. The recent research is about reconstruction of paleoclimate in two archeological sites of Konar sandal (KS (Jiroft and Tapeh Naderi (TN (Mashhad based on the microvertebrate and especially Tatera indica species. In these sites we attempted to solve the palaeoenvironment condition by analysis of rodent remains which hold the greatest potential to monitoring of ecological parameters (Hoover et al. 1977; Getz 1961; Reig 1970; Merritt 1974. Combining of a rich network of data with using of morphological and morphometric methods; reconstruction of paleoenvironment; documentation and investigation of their relationship with the environment is the main result of this research .       Material & Methods   In both zooarchaeological samples which are composed of juveniles and young individual rodent, (KS, NISP=800 and TN, NISP=3 cranial and postcranial remains were sorted anatomically and washed with water. Dental pattern of mandible and maxillary tooth rows were drowns using a drawing tube connecting to a stereomicroscope (Olympus SZH-10. All recovered teeth fragments were measured based on the greatest dental length and width of the upper and lower jaw molars when

  13. Aborigines of the nuclear desert

    International Nuclear Information System (INIS)

    Rujula, A. de

    1985-01-01

    The chart of 'stable nuclides' extends from Hydrogen, to Z proportional 98, A proportional 263. It contains another island of stability - neutron stars - in a narrow range around Z proportional 10 56 , A proportional 10 57 . In between lies a supposedly barren region encompassing more than 50 orders of magnitude. This desert may be populated by strange quark balls: Stable single bags containing similar proportions of u, d and s quarks. These balls are candidates for the constituency of the 'dark mass' in galaxies and in the Universe. We describe seven ways to search for these possible inhabitants of the nuclear desert. (orig.)

  14. Russian deserters of World War I

    OpenAIRE

    Os'kin Maksim

    2014-01-01

    Desertion is one of the most active forms of ordinary resistance of the people to the state pressure during the low-popular war which is conducting for the purposes unclear for the people. At the same time, mass desertion is a manifestation of «total» war in the world conflicts of the XX century. During World War I in all armies of the world there was the desertion often accepting mass character. In the Russian army, as well as in other, deserters appeared from the war beginning. Desertion sca...

  15. Patterns and timing of loess-paleosol transitions in Eurasia: Constraints for paleoclimate studies

    Science.gov (United States)

    Zeeden, Christian; Hambach, Ulrich; Obreht, Igor; Hao, Qingzhen; Abels, Hemmo A.; Veres, Daniel; Lehmkuhl, Frank; Gavrilov, Milivoj B.; Marković, Slobodan B.

    2018-03-01

    Loess-paleosol sequences are the most extensive terrestrial paleoclimate records in Europe and Asia documenting atmospheric circulation patterns, vegetation, and sedimentary dynamics in response to glacial-interglacial cyclicity. Between the two sides of the Eurasian continent, differences may exist in response and response times to glacial changes and finding these is essential to understand the climate systems of the northern hemisphere. Therefore, assessment of common patterns and regional differences in loess-paleosol sequences (LPS) is vital, but remains, however, uncertain. Another key to interpret these records is to constrain the mechanisms responsible for the formation and preservation of paleosols and loess layers in these paleoclimate archives. This study therefore compares LPS magnetic susceptibility records as proxies for paleosol formation intensity for selected sites from the central Chinese Loess Plateau and the Carpathian Basin in Europe over the last 440 kyr. Inconsistencies and crucial issues concerning the timing, correlation and paleoclimate potential of selected Eurasian LPS are outlined. Our comparison of Eurasian LPS shows generally similar patterns of paleosol formation, while highlighting several crucial differences. Especially for paleosols developed around 200 and 300 ka, the reported timing of soil formation differs by up to 30 ka. In addition, a drying and cooling trend over the last 300 ka has been documented in Europe, with no such evidence in the Asian records. The comparison shows that there is still uncertainty in defining the chronostratigraphic framework for these records on glacial-interglacial time scales in the order of 5-30 kyr for the last 440 ka. We argue that the baseline of the magnetic susceptibility proxy in loess from the Carpathian Basin is the most striking difference between European LPS and the Chinese Loess Plateau. In our opinion, many of the current timing/age differences may be overcome once a comparable

  16. Nd isotope constraints on ocean circulation, paleoclimate, and continental drainage during the Jurassic breakup of Pangea

    DEFF Research Database (Denmark)

    Dera, Guillaume; Prunier, Jonathan; Smith, Paul L.

    2015-01-01

    , western Russia, and North America. Combined with an extensive compilation of published εNd(t) data, our results show that the continental sources of Nd were very heterogeneous across the world. Volcanic inputs from a Jurassic equivalent of the modern Pacific Ring of Fire contributed to radiogenic ε......-Tethyan, and western Russian waters varied quite similarly through time, in response to regional changes in oceanic circulation, paleoclimate, continental drainage, and volcanism. Three positive shifts in εNd(t) values occurred successively in these epicontinental seas during the Pliensbachian, in the Aalenian...

  17. Desert Pathfinder at Work

    Science.gov (United States)

    2005-09-01

    The Atacama Pathfinder Experiment (APEX) project celebrates the inauguration of its outstanding 12-m telescope, located on the 5100m high Chajnantor plateau in the Atacama Desert (Chile). The APEX telescope, designed to work at sub-millimetre wavelengths, in the 0.2 to 1.5 mm range, passed successfully its Science Verification phase in July, and since then is performing regular science observations. This new front-line facility provides access to the "Cold Universe" with unprecedented sensitivity and image quality. After months of careful efforts to set up the telescope to work at the best possible technical level, those involved in the project are looking with satisfaction at the fruit of their labour: APEX is not only fully operational, it has already provided important scientific results. "The superb sensitivity of our detectors together with the excellence of the site allow fantastic observations that would not be possible with any other telescope in the world," said Karl Menten, Director of the group for Millimeter and Sub-Millimeter Astronomy at the Max-Planck-Institute for Radio Astronomy (MPIfR) and Principal Investigator of the APEX project. ESO PR Photo 30/05 ESO PR Photo 30/05 Sub-Millimetre Image of a Stellar Cradle [Preview - JPEG: 400 x 627 pix - 200k] [Normal - JPEG: 800 x 1254 pix - 503k] [Full Res - JPEG: 1539 x 2413 pix - 1.3M] Caption: ESO PR Photo 30/05 is an image of the giant molecular cloud G327 taken with APEX. More than 5000 spectra were taken in the J=3-2 line of the carbon monoxide molecule (CO), one of the best tracers of molecular clouds, in which star formation takes place. The bright peak in the north of the cloud is an evolved star forming region, where the gas is heated by a cluster of new stars. The most interesting region in the image is totally inconspicuous in CO: the G327 hot core, as seen in methanol contours. It is a truly exceptional source, and is one of the richest sources of emission from complex organic molecules in the

  18. Ecosystem biophysical memory in the southwestern North America climate system

    International Nuclear Information System (INIS)

    Forzieri, G; Feyen, L; Vivoni, E R

    2013-01-01

    To elucidate the potential role of vegetation to act as a memory source in the southwestern North America climate system, we explore correlation structures of remotely sensed vegetation dynamics with precipitation, temperature and teleconnection indices over 1982–2006 for six ecoregions. We found that lagged correlations between vegetation dynamics and climate variables are modulated by the dominance of monsoonal or Mediterranean regimes and ecosystem-specific physiological processes. Subtropical and tropical ecosystems exhibit a one month lag positive correlation with precipitation, a zero- to one-month lag negative correlation with temperature, and modest negative effects of sea surface temperature (SST). Mountain forests have a zero month lag negative correlation with precipitation, a zero–one month lag negative correlation with temperature, and no significant correlation with SSTs. Deserts show a strong one–four month lag positive correlation with precipitation, a low zero–two month lag negative correlation with temperature, and a high four–eight month lag positive correlation with SSTs. The ecoregion-specific biophysical memories identified offer an opportunity to improve the predictability of land–atmosphere interactions and vegetation feedbacks onto climate. (letter)

  19. Inverted stream channels in the Western Desert of Egypt: Synergistic remote, field observations and laboratory analysis on Earth with applications to Mars

    Science.gov (United States)

    Zaki, Abdallah S.; Pain, Colin F.; Edgett, Kenneth S.; Giegengack, Robert

    2018-07-01

    Inverted relief landforms occur in numerous regions on Mars, ranging in age from Noachian to more recent Amazonian periods (channel features on Earth form, and the geologic records they preserve in arid settings, can yield insights into the development of inverted landforms on Mars. Inverted channel landforms in the Western Desert of Egypt are well represented across an area of ∼27,000 km2. We investigated inverted channel features at seven sites using remotely-sensed data, field observations, and lab analysis. Inverted channel features in the Western Desert record fluvial environments of differing scales and ages. They developed mainly via inversion of cemented valley floor sediment, but there is a possibility that inverted fluvial landforms in the Dakhla Depression might have been buried, lithified, and exhumed. A few examples, in the southeastern part of the Western Desert, record, instead, a resistance to erosion caused by surface armouring of uncemented valley floor sediment. We show that the grain-size distribution for investigated and reviewed inverted channels is highly variable, with boulders that are commonly 0.35 - 1 m in size; large particles provide high porosity that influences the cementation mechanism. The studied inverted channel sediments are mainly cemented with ferricrete, calcrete, gypcrete, and silcrete. Inverted channels are valuable for the reconstruction of paleoclimate cycles or episodes on Earth and Mars; observations from the Western Desert, when offered as analogs, add to the growing list of Earth examples that provide suites of observables relevant to reconstruction of paleoenvironmental conditions on Mars.

  20. EFFECTS OF ELEVATED CO2 ON ROOT FUNCTION AND SOIL RESPIRATION IN A MOJAVE DESERT ECOSYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, Robert S.

    2007-12-19

    belowground in relatively recalcitrant forms. Indeed, a model-based analysis predicted that the arid/semiarid southwestern bioclimatic region had one of the highest rates of net carbon storage in the United States over the past century (Schimel et al. 2000). Second, root systems of desert plants are often extensive (Foxx et al. 1984, Hartle et al. 2006) with relatively large proportions of roots deep in the soil (Schenk & Jackson 2002). Thus, an understanding of belowground processes in desert ecosystems provides information on the potential for terrestrial carbon sequestration in desert ecosystems.

  1. The geochemical associations of nitrate and naturally formed perchlorate in the Mojave Desert, California, USA

    Science.gov (United States)

    Lybrand, Rebecca A.; Michalski, Greg; Graham, Robert C.; Parker, David R.

    2013-03-01

    Perchlorate is a widely studied environmental contaminant that may adversely affect human health, and whose natural occurrence has emerged as a subject of great interest. Naturally formed perchlorate has been found to co-occur with nitrate in arid environments worldwide, but the relationship is not fully understood in the desert soils of the southwestern United States. The main objective of this research was to explore the origin, pedogenic distribution, and possible preservation of perchlorate and nitrate in the Mojave Desert mud hill deposits of California and to determine if the co-occurrence of putatively natural perchlorate was significantly correlated with nitrate in these soils. We identified 39 soil horizons in the Mojave Desert, California that contained reportable levels of perchlorate (MRL >165 μg kg-1) with a maximum concentration of 23 mg kg-1. A weak yet significant correlation was observed between perchlorate and nitrate (r2 = 0.321∗∗∗), which could be indicative of similar mechanisms of accumulation. When compared to published data for the Atacama Desert, the Mojave Desert perchlorate concentrations were remarkably lower for a given nitrate concentration. Oxygen isotopes in the nitrate were examined to identify variation within the Mojave Desert field sites, and to compare with the available literature for the Atacama Desert. The Mojave Desert Δ17O values ranged from 7‰ to 13‰, indicating a mixture of biologically and atmospherically-derived nitrate. An investigation of the distribution of perchlorate among soil horizons revealed that over sixty percent of the samples containing perchlorate were from C horizons while only twenty percent of the samples were from B horizons and even fewer in the overlying A horizons. Soil chemical, morphologic, and geologic characteristics of the soils suggest that the perchlorate, nitrate and/or other soluble salts have moved in a "bottom-up" manner wherein the salts were deposited in strata through

  2. A simple conceptual model to interpret the 100 000 years dynamics of paleo-climate records

    Directory of Open Access Journals (Sweden)

    C. S. Quiroga Lombard

    2010-10-01

    Full Text Available Spectral analyses performed on records of cosmogenic nuclides reveal a group of dominant spectral components during the Holocene period. Only a few of them are related to known solar cycles, i.e., the De Vries/Suess, Gleissberg and Hallstatt cycles. The origin of the others remains uncertain. On the other hand, time series of North Atlantic atmospheric/sea surface temperatures during the last ice age display the existence of repeated large-scale warming events, called Dansgaard-Oeschger (DO events, spaced around multiples of 1470 years. The De Vries/Suess and Gleissberg cycles with periods close to 1470/7 (~210 and 1470/17 (~86.5 years have been proposed to explain these observations. In this work we found that a conceptual bistable model forced with the De Vries/Suess and Gleissberg cycles plus noise displays a group of dominant frequencies similar to those obtained in the Fourier spectra from paleo-climate during the Holocene. Moreover, we show that simply changing the noise amplitude in the model we obtain similar power spectra to those corresponding to GISP2 δ18O (Greenland Ice Sheet Project 2 during the last ice age. These results give a general dynamical framework which allows us to interpret the main characteristic of paleoclimate records from the last 100 000 years.

  3. Objectively combining AR5 instrumental period and paleoclimate climate sensitivity evidence

    Science.gov (United States)

    Lewis, Nicholas; Grünwald, Peter

    2018-03-01

    Combining instrumental period evidence regarding equilibrium climate sensitivity with largely independent paleoclimate proxy evidence should enable a more constrained sensitivity estimate to be obtained. Previous, subjective Bayesian approaches involved selection of a prior probability distribution reflecting the investigators' beliefs about climate sensitivity. Here a recently developed approach employing two different statistical methods—objective Bayesian and frequentist likelihood-ratio—is used to combine instrumental period and paleoclimate evidence based on data presented and assessments made in the IPCC Fifth Assessment Report. Probabilistic estimates from each source of evidence are represented by posterior probability density functions (PDFs) of physically-appropriate form that can be uniquely factored into a likelihood function and a noninformative prior distribution. The three-parameter form is shown accurately to fit a wide range of estimated climate sensitivity PDFs. The likelihood functions relating to the probabilistic estimates from the two sources are multiplicatively combined and a prior is derived that is noninformative for inference from the combined evidence. A posterior PDF that incorporates the evidence from both sources is produced using a single-step approach, which avoids the order-dependency that would arise if Bayesian updating were used. Results are compared with an alternative approach using the frequentist signed root likelihood ratio method. Results from these two methods are effectively identical, and provide a 5-95% range for climate sensitivity of 1.1-4.05 K (median 1.87 K).

  4. On the importance of paleoclimate modelling for improving predictions of future climate change

    Directory of Open Access Journals (Sweden)

    J. C. Hargreaves

    2009-12-01

    Full Text Available We use an ensemble of runs from the MIROC3.2 AGCM with slab-ocean to explore the extent to which mid-Holocene simulations are relevant to predictions of future climate change. The results are compared with similar analyses for the Last Glacial Maximum (LGM and pre-industrial control climate. We suggest that the paleoclimate epochs can provide some independent validation of the models that is also relevant for future predictions. Considering the paleoclimate epochs, we find that the stronger global forcing and hence larger climate change at the LGM makes this likely to be the more powerful one for estimating the large-scale changes that are anticipated due to anthropogenic forcing. The phenomena in the mid-Holocene simulations which are most strongly correlated with future changes (i.e., the mid to high northern latitude land temperature and monsoon precipitation do, however, coincide with areas where the LGM results are not correlated with future changes, and these are also areas where the paleodata indicate significant climate changes have occurred. Thus, these regions and phenomena for the mid-Holocene may be useful for model improvement and validation.

  5. Southwestern Power Administration Annual Report 2012

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-09-01

    Dear Secretary Moniz: I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2012. In FY 2012, Southwestern delivered over 4.1 billion kilowatt-hours of energy to its wholesale customers in Arkansas, Kansas, Louisiana, Missouri, Oklahoma, and Texas, generating $195 million in revenue. In fulfilling its mission to market and reliably deliver renewable Federal hydroelectric power, Southwestern maintains 1,380 miles of high-voltage transmission lines, substations, and communications sites, contributing to the reliability of the regional and National electric grid. Southwestern also actively partners with the Department of Energy, the U.S. Army Corps of Engineers, Southwestern’s customers, and other Federal power stakeholders to most effectively balance their diverse interests with Southwestern’s mission while continuing to maximize Federal assets to repay the Federal investment in the 24 hydropower facilities within Southwestern’s marketing region. Southwestern is proud of its past successes, and we look forward to continuing to serve the Nation’s energy needs in the future. Sincerely, Christopher M. Turner Administrator

  6. Southwestern Power Administration Annual Report 2010

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-09-01

    Dear Secretary Chu: I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2010. In FY 2010, Southwestern delivered nearly 7.6 billion kilowatt-hours of energy to its wholesale customers in Arkansas, Kansas, Louisiana, Missouri, Texas, and Oklahoma, generating $189 million in revenue. In fulfilling its mission to market and reliably deliver renewable Federal hydroelectric power, Southwestern maintains 1,380 miles of high-voltage transmission lines, substations, and communications sites, contributing to the reliability of the regional and National electric grid. Southwestern also actively partners with the Department of Energy, the U.S. Army Corps of Engineers, Southwestern’s customers, and other Federal power stakeholders to most effectively balance their diverse interests with Southwestern’s mission while continuing to maximize Federal assets to repay the Federal investment in the 24 hydropower facilities within Southwestern’s marketing region. Southwestern is proud of its past successes, and we look forward to continuing to serve the Nation’s energy needs in the future. Sincerely, Christopher M. Turner Administrator

  7. Southwestern Power Administration Annual Report 2011

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-04-01

    Dear Secretary Chu: I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2011. In FY 2011, Southwestern delivered over 4.1 billion kilowatt-hours of energy to its wholesale customers in Arkansas, Kansas, Louisiana, Missouri, Oklahoma, and Texas, generating $167 million in revenue. In fulfilling its mission to market and reliably deliver renewable Federal hydroelectric power, Southwestern maintains 1,380 miles of high-voltage transmission lines, substations, and communications sites, contributing to the reliability of the regional and National electric grid. Southwestern also actively partners with the Department of Energy, the U.S. Army Corps of Engineers, Southwestern’s customers, and other Federal power stakeholders to most effectively balance their diverse interests with Southwestern’s mission while continuing to maximize Federal assets to repay the Federal investment in the 24 hydropower facilities within Southwestern’s marketing region. Southwestern is proud of its past successes, and we look forward to continuing to serve the Nation’s energy needs in the future. Sincerely, Christopher M. Turner Administrator

  8. Paleoclimate Modeling

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Computer simulations of past climate. Variables provided as model output are described by parameter keyword. In some cases the parameter keywords are a subset of all...

  9. Influence of surface roughness of a desert

    Science.gov (United States)

    Sud, Y. C.; Smith, W. E.

    1984-01-01

    A numerical simulation study, using the current GLAS climate GCM, was carried out to examine the influence of low bulk aerodynamic drag parameter in the deserts. The results illustrate the importance of yet another feedback effect of a desert on itself, that is produced by the reduction in surface roughness height of land once the vegetation dies and desert forms. Apart from affecting the moisture convergence, low bulk transport coefficients of a desert lead to enhanced longwave cooling and sinking which together reduce precipitation by Charney's (1975) mechanism. Thus, this effect, together with albedo and soil moisture influence, perpetuate a desert condition through its geophysical feedback effect. The study further suggests that man made deserts is a viable hypothesis.

  10. STATISTICAL INVESTIGATION OF THE GROUNDWATER SYSTEM IN DARB EL-ARBAEIN, SOUTHWESTERN DESERT, EGYPT

    Directory of Open Access Journals (Sweden)

    Kashouty Mohamed El

    2009-12-01

    Full Text Available In Darb El Arbaein, the groundwater is the only water resources. The aquifer system starts from Paleozoic-Mesozoic to Upper Cretaceous sandstone rocks. They overlay the basement rocks and the aquifer is confined. In the present research, the performance of the statistical analyses to classify groundwater samples depending on their chemical characters has been tested. The hydrogeological and hydrogeochemical data of 92 groundwater samples was obtained from the GARPAD authority in northern, central, and southern Darb El Arbaein. A robust classification scheme for partitioning groundwater chemistry into homogeneous groups was an important tool for the characterization of Nubian sandstone aquifer. We test the performance of the many available graphical and statistical methodologies used to classify water samples. R-mode, Q-mode, correlation analysis, and principal component analysis were investigated. All the methods were discussed and compared as to their ability to cluster, ease of use, and ease of interpretation. The correlation investigation clarifies the relationship among the lithology, hydrogeology, and anthropogenic. Factor investigation revealed three factors namely; the evaporation process-agriculturalimpact-lithogenic dissolution, the hydrogeological characteristics of the aquifer system, and the surface meteoric water that rechargethe aquifer system. Two main clusters that subdivided into four sub clusters were identified in groundwater system based on hydrogeological and hydrogeochemical data. They reflect the impact of geomedia, hydrogeology, geographic position, and agricultural wastewater. The groundwater is undersaturated with respect to most selected minerals. The groundwater was supersaturated with respect to iron minerals in northern and southern Darb El Arbaein. The partial pressure of CO2 of the groundwater versus saturation index of calcite shows the gradual change in PCO2 from atmospheric to the present aquifer pressures.

  11. Regional water table (2016) in the Mojave River and Morongo groundwater basins, southwestern Mojave Desert, California

    Science.gov (United States)

    Dick, Meghan; Kjos, Adam

    2017-12-07

    From January to April 2016, the U.S. Geological Survey (USGS), the Mojave Water Agency, and other local water districts made approximately 1,200 water-level measurements in about 645 wells located within 15 separate groundwater basins, collectively referred to as the Mojave River and Morongo groundwater basins. These data document recent conditions and, when compared with older data, changes in groundwater levels. A water-level contour map was drawn using data measured in 2016 that shows the elevation of the water table and general direction of groundwater movement for most of the groundwater basins. Historical water-level data stored in the USGS National Water Information System (https://waterdata.usgs.gov/nwis/) database were used in conjunction with data collected for this study to construct 37 hydrographs to show long-term (1930–2016) and short-term (1990–2016) water-level changes in the study area.

  12. The sedimentary record and petrophysical logs from the Spanish Central Pyrenees: Implications for paleoclimate change in the Early Devonian

    Czech Academy of Sciences Publication Activity Database

    Slavík, Ladislav; Valenzuela-Ríos, J. I.; Hladil, Jindřich; Chadimová, Leona; Liao, J-Ch.; Hušková, Aneta; Calvo, H.; Hrstka, Tomáš

    2015-01-01

    Roč. 21, - (2015), s. 350-350 ISSN 1608-8166. [International Congress on Stratigraphy /2./. STRATI 2015. 19.07.2015-23.07.2015, Graz] Institutional support: RVO:67985831 Keywords : stratigraphy * Early Devonian * sedimentary record * paleoclimate change * Spanish Central Pyrenees Subject RIV: DB - Geology ; Mineralogy http://www.zobodat.at/pdf/Ber-Inst-Erdwiss-Univ-Graz_21_0001-0437.pdf

  13. A two millennium-long hot drought in the southwestern United States driven by Arctic sea-ice retreat

    Science.gov (United States)

    Lachniet, M. S.; Asmerom, Y.; Polyak, V. J.; Denniston, R. F.

    2017-12-01

    The Great Basin and lower Colorado River Basin are susceptible to sustained droughts that impact water resources and economic activity for millions of residents of the southwestern United States. The causes of past droughts in the basin remain debated. Herein, we document a strong Arctic to mid-latitude teleconnection during the Holocene that resulted in an extreme `hot drought' persisting for more than two millennia in the southwestern United States, based on a continuous growth rate and new high-resolution carbon and oxygen isotopic time series from a precisely-dated stalagmite from Leviathan Cave, Nevada. Between 9850-7670 yr B2k, highest Holocene oxygen isotope values indicate warm temperatures and moisture-sensitive proxies of high carbon isotope values and low stalagmite growth rate and minimal soil productivity and aquifer recharge. We refer to this period as the Altithermal Hot Drought. A second interval (6770 to 5310 yr B2k) indicates a warm drought. The two Altithermal droughts exceed in severity and duration any droughts observed in the modern and tree-ring records. Further, we show that Altithermal hot droughts were widespread in the southwestern United States, at a time when human populations in the Great Basin were low. The droughts show strong similarities to proxies for Arctic paleoclimate and we suggest that insolation-driven changes in sea ice and snow cover extent in the high latitudes drove atmospheric circulation anomalies in the Great Basin. Because rising greenhouse gas concentrations are projected to increase global and Arctic temperatures with a possible loss of summer sea by the end of the 21st century, our record suggests that a return to prolonged hotter and drier conditions in the southern Great Basin and lower Colorado River Basin is possible within coming centuries.

  14. Estimating wildfire risk on a Mojave Desert landscape using remote sensing and field sampling

    Science.gov (United States)

    Van Linn, Peter F.; Nussear, Kenneth E.; Esque, Todd C.; DeFalco, Lesley A.; Inman, Richard D.; Abella, Scott R.

    2013-01-01

    Predicting wildfires that affect broad landscapes is important for allocating suppression resources and guiding land management. Wildfire prediction in the south-western United States is of specific concern because of the increasing prevalence and severe effects of fire on desert shrublands and the current lack of accurate fire prediction tools. We developed a fire risk model to predict fire occurrence in a north-eastern Mojave Desert landscape. First we developed a spatial model using remote sensing data to predict fuel loads based on field estimates of fuels. We then modelled fire risk (interactions of fuel characteristics and environmental conditions conducive to wildfire) using satellite imagery, our model of fuel loads, and spatial data on ignition potential (lightning strikes and distance to roads), topography (elevation and aspect) and climate (maximum and minimum temperatures). The risk model was developed during a fire year at our study landscape and validated at a nearby landscape; model performance was accurate and similar at both sites. This study demonstrates that remote sensing techniques used in combination with field surveys can accurately predict wildfire risk in the Mojave Desert and may be applicable to other arid and semiarid lands where wildfires are prevalent.

  15. Uranium distribution in Baikal sediments using SSNTD method for paleoclimate reconstruction

    CERN Document Server

    Zhmodik, S M; Nemirovskaya, N A; Zhatnuev, N S

    1999-01-01

    First data on local distribution of uranium in the core of Lake Baikal floor sediments (Academician ridge, VER-95-2, St 3 BC, 53 deg. 113'12'N/108 deg. 25'01'E) are presented in this paper. They have been obtained using (n,f)-radiography. Various forms of U-occurrence in floor sediments are shown, i.e. evenly disseminated, associated with clayey and diatomaceous components; micro- and macroinclusions of uranium bearing minerals - microlocations with uranium content 10-50 times higher than U-concentrations associated with clayey and diatomaceous components. Relative and absolute U-concentration can be determined for every mineral. Signs of various order periodicity of U-distribution in the core of Lake Baikal floor sediments have been found. Using (n,f)-radiography method of the study of Baikal floor sediment permits gathering of new information that can be used at paleoclimate reconstruction.

  16. Recent eolian activity and paleoclimate fluctuations in the Ferris Lost Soldier Area, South-Central Wyoming

    Science.gov (United States)

    Gaylord, D. R.

    1983-09-01

    The Ferris Dune Fields were examined. Sand dunes are especially valuable in paleoclimate reconstructions because they: (1) bury and preserve datable materials and artifacts; (2) respond to even subtle changes in wind velocity and direction as reflected both in external morphology and internal structures; and (3) remain unconsolidated, making them amenable to easy textural and compositional examination. The valley of Clear Creek in the Ferris Dunes reveals a relatively continuous Holocene section of interbedded dune and interdunal pond deposits. Radiocarbon dates from the interdunal pond strata at Clear Creek, theoretical sand dune migration rates, compositional analysis of periglacial sand wedges, and relative dating of actively migrating parabolic dunes reveals a general sequence of geologic-climatic events that affected the Ferris-Lost Soldier area. The most recent major reactivaton of dunes occurred approximately 290 years ago.

  17. A national perspective on paleoclimate streamflow and water storage infrastructure in the conterminous United States

    Science.gov (United States)

    Ho, Michelle; Lall, Upmanu; Sun, Xun; Cook, Edward

    2017-04-01

    Large-scale water storage infrastructure in the Conterminous United States (CONUS) provides a means of regulating the temporal variability in water supply with storage capacities ranging from seasonal storage in the wetter east to multi-annual and decadal-scale storage in the drier west. Regional differences in water availability across the CONUS provides opportunities for optimizing water dependent economic activities, such as food and energy production, through storage and transportation. However, the ability to sufficiently regulate water supplies into the future is compromised by inadequate monitoring of non-federally-owned dams that make up around 97% of all dams. Furthermore, many of these dams are reaching or have exceeded their economic design life. Understanding the role of dams in the current and future landscape of water requirements in the CONUS is needed to prioritize dam safety remediation or identify where redundant dams may be removed. A national water assessment and planning process is needed for addressing water requirements, accounting for regional differences in water supply and demand, and the role of dams in such a landscape. Most dams in the CONUS were designed without knowledge of devastating floods and prolonged droughts detected in multi-centennial paleoclimate records, consideration of projected climate change, nor consideration of optimal operation across large-scale regions. As a step towards informing water supply across the CONUS we present a paleoclimate reconstruction of annual streamflow across the CONUS over the past 555 years using a spatially and temporally complete paleoclimate record of summer drought across the CONUS targeting a set of US Geological Survey streamflow sites. The spatial and temporal structures of national streamflow variability are analyzed using hierarchical clustering, principal component analysis, and wavelet analyses. The reconstructions show signals of contemporary droughts such as the Dust Bowl (1930s

  18. Paleoclimate from fossil plants and application to the early Cenozoic Rocky Mountains

    Science.gov (United States)

    Wing, S. L.

    2011-12-01

    Wladimir Köppen called vegetation "crystallized, visible climate," and his metaphor encouraged paleobotanists to climb the chain of inference from fossil plants to paleovegetation to paleoclimate. Inferring paleovegetation from fossils has turned out to be very difficult, however, and today most paleobotanical methods for inferring paleoclimate do not try to reconstruct paleovegetation as a first step. Three major approaches are widely use to infer paleoclimate from plant fossils: 1) phylogenetic inferences rely on the climatic distributions of extant relatives of fossils, 2) morphological inferences use present-day correlations of climate with plant morphology (e.g, leaf shape, wood anatomy), and 3) chemical inferences rely on correlations between climate and the stable isotopic composition of plants or organic compounds. Each approach makes assumptions that are hard to verify. Phylogenetic inference depends on accurate identification of fossils, and also assumes that evolution and/or extinction has not shifted the climatic distributions of plant lineages through time. On average this assumption is less valid for older time periods, but probably it is not radically wrong for the early Cenozoic. Morphological approaches don't require taxonomic identification of plant fossils, but do assume that correlations between plant form and climate have been constant over time. This assumption is bolstered if the ecophysiological cause of the morphology-climate correlation is well understood, but often it isn't. Stable isotopic approaches assume that present-day correlations between isotopic composition and climate apply to the past. Commonly the chemical and physiological mechanisms responsible for the correlation are moderately well known, but often the variation among different taxonomic and functional groups of plants is poorly characterized. In spite of limitations and uncertainties on all methods for inferring paleoclimate from fossil plants, broad patterns emerge from

  19. Autogenic geomorphic processes determine the resolution and fidelity of terrestrial paleoclimate records.

    Science.gov (United States)

    Foreman, Brady Z; Straub, Kyle M

    2017-09-01

    Terrestrial paleoclimate records rely on proxies hosted in alluvial strata whose beds are deposited by unsteady and nonlinear geomorphic processes. It is broadly assumed that this renders the resultant time series of terrestrial paleoclimatic variability noisy and incomplete. We evaluate this assumption using a model of oscillating climate and the precise topographic evolution of an experimental alluvial system. We find that geomorphic stochasticity can create aliasing in the time series and spurious climate signals, but these issues are eliminated when the period of climate oscillation is longer than a key time scale of internal dynamics in the geomorphic system. This emergent autogenic geomorphic behavior imparts regularity to deposition and represents a natural discretization interval of the continuous climate signal. We propose that this time scale in nature could be in excess of 10 4 years but would still allow assessments of the rates of climate change at resolutions finer than the existing age model techniques in isolation.

  20. Distance-decay relationships partially determine diversity patterns of phyllosphere bacteria on Tamarix trees across the Sonoran Desert [corrected].

    Science.gov (United States)

    Finkel, Omri M; Burch, Adrien Y; Elad, Tal; Huse, Susan M; Lindow, Steven E; Post, Anton F; Belkin, Shimshon

    2012-09-01

    Dispersal limitation in phyllosphere communities was measured on the leaf surfaces of salt-excreting Tamarix trees, which offer unique, discrete habitats for microbial assemblages. We employed 16S rRNA gene pyrosequencing to measure bacterial community dissimilarity on leaves of spatially dispersed Tamarix specimens in sites with uniform climatic conditions across the Sonoran Desert in the Southwestern United States. Our analyses revealed diverse bacterial communities with four dominant phyla that exhibited differential effects of environmental and geographic variables. Geographical distance was the most important parameter that affected community composition, particularly that of betaproteobacteria, which displayed a statistically significant, distance-decay relationship.

  1. The Riparianness of a Desert Herpetofauna

    Science.gov (United States)

    Charles H. Lowe

    1989-01-01

    Within the Mojave, Sonoran, and Chihuahuan Desert subdivisions of the North American Desert in the U.S., more than half of 143 total amphibian and reptilian species perform as riparian and/or wetland taxa. For the reptiles, but not the amphibians, there is a significant inverse relationship between riparianness (obligate through preferential and facultative to...

  2. Discriminating patterns and drivers of multiscale movement in herpetofauna: The dynamic and changing environment of the Mojave desert tortoise.

    Science.gov (United States)

    Sadoti, Giancarlo; Gray, Miranda E; Farnsworth, Matthew L; Dickson, Brett G

    2017-09-01

    Changes to animal movement in response to human-induced changes to the environment are of growing concern in conservation. Most research on this problem has focused on terrestrial endotherms, but changes to herpetofaunal movement are also of concern given their limited dispersal abilities and specialized thermophysiological requirements. Animals in the desert region of the southwestern United States are faced with environmental alterations driven by development (e.g., solar energy facilities) and climate change. Here, we study the movement ecology of a desert species of conservation concern, the Mojave desert tortoise ( Gopherus agassizii ). We collected weekly encounter locations of marked desert tortoises during the active (nonhibernation) seasons in 2013-2015, and used those data to discriminate movements among activity centers from those within them. We then modeled the probability of movement among activity centers using a suite of covariates describing characteristics of tortoises, natural and anthropogenic landscape features, vegetation, and weather. Multimodel inference indicated greatest support for a model that included individual tortoise characteristics, landscape features, and weather. After controlling for season, date, age, and sex, we found that desert tortoises were more likely to move among activity centers when they were further from minor roads and in the vicinity of barrier fencing; we also found that movement between activity centers was more common during periods of greater rainfall and during periods where cooler temperatures coincided with lower rainfall. Our findings indicate that landscape alterations and climate change both have the potential to impact movements by desert tortoises during the active season. This study provides an important baseline against which we can detect future changes in tortoise movement behavior.

  3. Rural childhoods in Egypt's desert lands

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine

    Based on fieldwork in Egypt’s desert lands, this paper discusses rural childhoods in an area experiencing rapid social and cultural change. Since 1987, the Egyptian Government has made new villages in the desert as a means to increase agricultural production and solving problems of unemployment....... Many settlers move to the Mubarak villages in order to give their children a good start in life. The desert villages are associated with a type of ‘rural idyll’. The process of settling in the desert impacts upon the children’s possible pathways to adulthood and their identities and social......’s new roles impact upon the children’s lives. The social contexts shaping the desert childhoods are in some ways more similar to contexts in ‘developed’ countries than in other parts of rural Egypt. The paper ends up by contrasting ideas of rural childhoods in Egypt with those found in ‘developed...

  4. Russian deserters of World War I

    Directory of Open Access Journals (Sweden)

    Os'kin Maksim

    2014-10-01

    Full Text Available Desertion is one of the most active forms of ordinary resistance of the people to the state pressure during the low-popular war which is conducting for the purposes unclear for the people. At the same time, mass desertion is a manifestation of «total» war in the world conflicts of the XX century. During World War I in all armies of the world there was the desertion often accepting mass character. In the Russian army, as well as in other, deserters appeared from the war beginning. Desertion scales in the Russian army explained as objective factors - diffi cult fights, shortage of supply, defeat at the front, and subjective - unwillingness to participate in war, melancholy for the house, desire to help a family the work. Desertion in different years of war had various forms. If at the beginning of war there were mainly «self-arrows», in 1915, during defeats at the front - evasion from entrenchments. By the end of 1916, because of the general fatigue from war, desertion takes the real form - flight from the front to the back. After February revolution desertion becomes mass in which hundreds thousands military personnel take part already. Disorder of army and development of revolutionary process extremely strengthen desertion scales that is explained by the actual lack of punishment for this crime. Destruction of the Russian state during revolution became the main reason of coming to power of Bolsheviks, an exit of Russia from war and the army demobilization which essential part in 1917 already deserted from the front.

  5. Casuses of deforestation in southwestern Madagascar

    DEFF Research Database (Denmark)

    Casse, Thorkil; Milhøj, Anders; Ranaivoson, Socrate

    2004-01-01

    Causes of deforestation are discussed in the case of southwestern Madagascar. Distinction is made between direct and indirect causes. The article ends up with an estimation of the value of agricultural land vs. an estimation of benefits from utilisation of non-timber forest products......Causes of deforestation are discussed in the case of southwestern Madagascar. Distinction is made between direct and indirect causes. The article ends up with an estimation of the value of agricultural land vs. an estimation of benefits from utilisation of non-timber forest products...

  6. Status, ecology, and conservation of the southwestern willow flycatcher

    Science.gov (United States)

    Deborah M. Finch; Scott H. Stoleson

    2000-01-01

    This publication was prepared in response to a need expressed by southwestern agencies and organizations for a comprehensive assessment of the population status, history, biology, ecology, habitats, threats, and conservation of the southwestern willow flycatcher (Empidonax traillii extimus). The southwestern willow flycatcher was federally listed as...

  7. Regional signatures of plant response to drought and elevated temperature across a desert ecosystem

    Science.gov (United States)

    Munson, Seth M.; Muldavin, Esteban H.; Belnap, Jayne; Peters, Debra P.C.; Anderson, John P.; Reiser, M. Hildegard; Gallo, Kirsten; Melgoza-Castillo, Alicia; Herrick, Jeffrey E.; Christiansen, Tim A.

    2013-01-01

    The performance of many desert plant species in North America may decline with the warmer and drier conditions predicted by climate change models, thereby accelerating land degradation and reducing ecosystem productivity. We paired repeat measurements of plant canopy cover with climate at multiple sites across the Chihuahuan Desert over the last century to determine which plant species and functional types may be the most sensitive to climate change. We found that the dominant perennial grass, Bouteloua eriopoda, and species richness had nonlinear responses to summer precipitation, decreasing more in dry summers than increasing with wet summers. Dominant shrub species responded differently to the seasonality of precipitation and drought, but winter precipitation best explained changes in the cover of woody vegetation in upland grasslands and may contribute to woody-plant encroachment that is widespread throughout the southwestern United States and northern Mexico. Temperature explained additional variability of changes in cover of dominant and subdominant plant species. Using a novel empirically based approach we identified ‘‘climate pivot points’’ that were indicative of shifts from increasing to decreasing plant cover over a range of climatic conditions. Reductions in cover of annual and several perennial plant species, in addition to declines in species richness below the long-term summer precipitation mean across plant communities, indicate a decrease in the productivity for all but the most drought-tolerant perennial grasses and shrubs in the Chihuahuan Desert. Overall, our regional synthesis of long-term data provides a robust foundation for forecasting future shifts in the composition and structure of plant assemblages in the largest North American warm desert.

  8. The impact of desert solar power utilization on sustainable development

    International Nuclear Information System (INIS)

    Sadiq Ali Shah; Yang Zhang

    2011-01-01

    This paper evaluates the prospects of developing a solar based desert economy in the deserts of solar-rich countries. The potential deserts are analysed to study their positive impact on the sustainable development processes in these regions. The sustainability of the processes is established on the basis of self-contained nature of energy generation, environmental emission reduction and desert land reclamation. (authors)

  9. Long-term trends in restoration and associated land treatments in the southwestern United States

    Science.gov (United States)

    Copeland, Stella M.; Munson, Seth M.; Pilliod, David S.; Welty, Justin L.; Bradford, John B.; Butterfield, Bradley J.

    2018-01-01

    Restoration treatments, such as revegetation with seeding or invasive species removal, have been applied on U.S. public lands for decades. Temporal trends in these management actions have not been extensively summarized previously, particularly in the southwestern United States where invasive plant species, drought, and fire have altered dryland ecosystems. We assessed long-term (1940–2010) trends in restoration using approximately 4,000 vegetation treatments conducted on Bureau of Land Management lands across the southwestern United States. We found that since 1940, the proportions of seeding and vegetation/soil manipulation (e.g. vegetation removal or plowing) treatments have declined, while the proportions of prescribed burn and invasive species treatments have increased. Treatments in pinyon-juniper and big sagebrush communities declined in comparison to treatments in desert scrub, creosote bush, and riparian woodland communities. Restoration-focused treatment objectives increased relative to resource extraction objectives. Species richness and proportion of native species used in seeding treatments also increased. Inflation-adjusted costs per area rose 750% for vegetation/soil manipulation, 600% for seeding, and 400% for prescribed burn treatments in the decades from 1981 to 2010. Seeding treatments were implemented in warmer and drier years when compared to the climate conditions of the entire study period and warmer and wetter years relative to several years before and after the treatment. These results suggest that treatments over a 70-year period on public lands in the southwestern United States are shifting toward restoration practices that are increasingly large, expensive, and related to fire and invasive species control.

  10. Factors influencing woodlands of southwestern North Dakota

    Science.gov (United States)

    Michele M. Girard; Harold Goetz; Ardell J. Bjugstad

    1987-01-01

    Literature pertaining to woodlands of southwestern North Dakota is reviewed. Woodland species composition and distribution, and factors influencing woodland ecosystems such as climate, logging, fire, and grazing are described. Potential management and improvement techniques using vegetation and livestock manipulation have been suggested.

  11. Southwestern Institute of Physics annual report (2000)

    International Nuclear Information System (INIS)

    2001-01-01

    The research results and engineering progress of SWIP (Southwestern Institute of Physics) during the year of 2000 was summarized in this annual report. The contents divided into five parts: 1. tokamak experimental diagnoses and tokamak engineering; 2. fusion reactor and fusion reactor materials; 3. plasma theory and calculation; 4. technique development and application; 5. appendix 31 theses and presented in this report

  12. Deserts

    DEFF Research Database (Denmark)

    Graulund, Rune

    2016-01-01

    , comic sketches and lyrical reveries; travel writing is now a crucial focus for discussion across many subjects within the humanities and social sciences. An ideal starting point for beginners, but also offering new perspectives for those familiar with the field, The Routledge Companion to Travel Writing...

  13. Effects of desert wildfires on desert tortoise (Gopherus agassizii) and other small vertebrates

    Science.gov (United States)

    Esque, T.C.; Schwalbe, C.R.; DeFalco, L.A.; Duncan, R.B.; Hughes, T.J.

    2003-01-01

    We report the results of standardized surveys to determine the effects of wildfires on desert tortoises (Gopherus agassizii) and their habitats in the northeastern Mojave Desert and northeastern Sonoran Desert. Portions of 6 burned areas (118 to 1,750 ha) were examined for signs of mortality of vertebrates. Direct effects of fire in desert habitats included animal mortality and loss of vegetation cover. A range of 0 to 7 tortoises was encountered during surveys, and live tortoises were found on all transects. In addition to desert tortoises, only small (reptiles (11 taxa) were found dead on the study areas. We hypothesize that indirect effects of fire on desert habitats might result in changes in the composition of diets and loss of vegetation cover, resulting in an increase in predation and loss of protection from temperature extremes. These changes in habitat also might cause changes in vertebrate communities in burned areas.

  14. Desertions in nineteenth-century shipping: modelling quit behaviour

    OpenAIRE

    Jari Ojala; Jaakko Pehkonen; Jari Eloranta

    2013-01-01

    Ship jumping in foreign ports was widespread throughout the age of sail. Desertion by seamen was illegal, it occurred abroad, and men who deserted only seldom returned home. We analyse desertion quantitatively and link it to the broader question of quit behaviour and labour turnover. Though the better wages paid at the foreign ports were the main reason for desertion, the regression model of the determinants of desertion indicates that outside opportunities, such as migration, and monetary in...

  15. Southwestern Power Administration annual site environmental report CY 1997

    International Nuclear Information System (INIS)

    1998-01-01

    This report provides a synopsis of Southwestern Power Administration's (Southwestern's) effectiveness in managing its operations in an environmentally responsible manner. In CY 1997, the Office of Environmental, Safety, and Health was reorganized and incorporated into the Division of Acquisition and Property. The Division of Acquisition, Property, and Environmental Management maintains responsibility for development, oversight, and implementation of environmental programs. Senior Management at Southwestern has taken actions to increase environmental awareness throughout the organization. During CY 1997, (Southwestern) was not involved in any known programs or activities that had adverse impacts on the environment. The 1997 Environmental Appraisal, a portion of Southwestern's Self-Assessment and Appraisal Program, indicated approximately 90% compliance with Southwestern's written environmental programs. Southwestern continued to function throughout CY 1997 in an operations and maintenance posture with minor substation projects

  16. Southwestern Power Administration site environmental report for calendar year 1993

    International Nuclear Information System (INIS)

    1994-01-01

    During CY 93, Southwestern was not involved in any programs that had a direct effect on the environment, involving endangered species, protection of wetlands, or increased electromagnetic radiation. Southwestern continued to function throughout the year in an operations and maintenance posture with minor substation projects. Southwestern received an environmental management audit by the Department of Energy's Office of Environmental Audit (EH-24), during CY 1992. The purpose of the audit was to give Southwestern, DOE headquarters, and the Secretary an indication of the status of Southwestern management's effectiveness in discharging its duties in an environmentally responsible manner. The audit identified 17 findings. An action plan was developed and remediation of the findings has been accomplished. Several strengths were identified during the audit with regard to the environmental programs at Southwestern. Most importantly, senior management at Southwestern has taken actions to increase environmental awareness throughout the organization which is evidenced by the creation of the Environmental, Safety, Health, and Security Office

  17. The Antarctic Centennial Oscillation: A Natural Paleoclimate Cycle in the Southern Hemisphere That Influences Global Temperature

    Directory of Open Access Journals (Sweden)

    W. Jackson Davis

    2018-01-01

    Full Text Available We report a previously-unexplored natural temperature cycle recorded in ice cores from Antarctica—the Antarctic Centennial Oscillation (ACO—that has oscillated for at least the last 226 millennia. Here we document the properties of the ACO and provide an initial assessment of its role in global climate. We analyzed open-source databases of stable isotopes of oxygen and hydrogen as proxies for paleo-temperatures. We find that centennial-scale spectral peaks from temperature-proxy records at Vostok over the last 10,000 years occur at the same frequencies (±2.4% in three other paleoclimate records from drill sites distributed widely across the East Antarctic Plateau (EAP, and >98% of individual ACOs evaluated at Vostok match 1:1 with homologous cycles at the other three EAP drill sites and conversely. Identified ACOs summate with millennial periodicity to form the Antarctic Isotope Maxima (AIMs known to precede Dansgaard-Oeschger (D-O oscillations recorded in Greenland ice cores. Homologous ACOs recorded at the four EAP drill sites during the last glacial maximum appeared first at lower elevations nearest the ocean and centuries later on the high EAP, with latencies that exceed dating uncertainty >30-fold. ACO homologs at different drill sites became synchronous, however, during the warmer Holocene. Comparative spectral analysis suggests that the millennial-scale AIM cycle declined in period from 1500 to 800 years over the last 70 millennia. Similarly, over the last 226 millennia ACO repetition period (mean 352 years declined by half while amplitude (mean 0.67 °C approximately doubled. The period and amplitude of ACOs oscillate in phase with glacial cycles and related surface insolation associated with planetary orbital forces. We conclude that the ACO: encompasses at least the EAP; is the proximate source of D-O oscillations in the Northern Hemisphere; therefore affects global temperature; propagates with increased velocity as temperature

  18. Coupled hydromechanical paleoclimate analyses of density-dependant groundwater flow in discretely fractured crystalline rock settings

    Science.gov (United States)

    Normani, S. D.; Sykes, J. F.; Jensen, M. R.

    2009-04-01

    A high resolution sub-regional scale (84 km2) density-dependent, fracture zone network groundwater flow model with hydromechanical coupling and pseudo-permafrost, was developed from a larger 5734 km2 regional scale groundwater flow model of a Canadian Shield setting in fractured crystalline rock. The objective of the work is to illustrate aspects of regional and sub-regional groundwater flow that are relevant to the long-term performance of a hypothetical nuclear fuel repository. The discrete fracture dual continuum numerical model FRAC3DVS-OPG was used for all simulations. A discrete fracture zone network model delineated from surface features was superimposed onto an 789887 element flow domain mesh. Orthogonal fracture faces (between adjacent finite element grid blocks) were used to best represent the irregular discrete fracture zone network. The crystalline rock between these structural discontinuities was assigned properties characteristic of those reported for the Canadian Shield at the Underground Research Laboratory at Pinawa, Manitoba. Interconnectivity of permeable fracture features is an important pathway for the possibly relatively rapid migration of average water particles and subsequent reduction in residence times. The multiple 121000 year North American continental scale paleoclimate simulations are provided by W.R. Peltier using the University of Toronto Glacial Systems Model (UofT GSM). Values of ice sheet normal stress, and proglacial lake depth from the UofT GSM are applied to the sub-regional model as surface boundary conditions, using a freshwater head equivalent to the normal stress imposed by the ice sheet at its base. Permafrost depth is applied as a permeability reduction to both three-dimensional grid blocks and fractures that lie within the time varying permafrost zone. Two different paleoclimate simulations are applied to the sub-regional model to investigate the effect on the depth of glacial meltwater migration into the subsurface. In

  19. Desert potholes: Ephemeral aquatic microsystems

    Science.gov (United States)

    Chan, M.A.; Moser, K.; Davis, J.M.; Southam, G.; Hughes, K.; Graham, T.

    2005-01-01

    An enigma of the Colorado Plateau high desert is the "pothole", which ranges from shallow ephemeral puddles to deeply carved pools. The existence of prokaryotic to eukaryotic organisms within these pools is largely controlled by the presence of collected rainwater. Multivariate statistical analysis of physical and chemical limnologic data variables measured from potholes indicates spatial and temporal variations, particularly in water depth, manganese, iron, nitrate and sulfate concentrations and salinity. Variation in water depth and salinity are likely related to the amount of time since the last precipitation, whereas the other variables may be related to redox potential. The spatial and temporal variations in water chemistry affect the distribution of organisms, which must adapt to daily and seasonal extremes of fluctuating temperature (0-60 ??C), pH changes of as much as 5 units over 12 days, and desiccation. For example, many species become dormant when potholes dry, in order to endure intense heat, UV radiation, desiccation and freezing, only to flourish again upon rehydration. But the pothole organisms also have a profound impact on the potholes. Through photosynthesis and respiration, pothole organisms affect redox potential, and indirectly alter the water chemistry. Laboratory examination of dried biofilm from the potholes revealed that within 2 weeks of hydration, the surface of the desiccated, black biofilm became green from cyanobacterial growth, which supported significant growth in heterotrophic bacterial populations. This complex biofilm is persumably responsible for dissolving the cement between the sandstone grains, allowing the potholes to enlarge, and for sealing the potholes, enabling them to retain water longer than the surrounding sandstone. Despite the remarkable ability of life in potholes to persist, desert potholes may be extremely sensitive to anthropogenic effects. The unique limnology and ecology of Utah potholes holds great scientific

  20. A 507-year rainfall and runoff reconstruction for the Monsoonal North West, Australia derived from remote paleoclimate archives

    Science.gov (United States)

    Verdon-Kidd, Danielle C.; Hancock, Gregory R.; Lowry, John B.

    2017-11-01

    The Monsoonal North West (MNW) region of Australia faces a number of challenges adapting to anthropogenic climate change. These have the potential to impact on a range of industries, including agricultural, pastoral, mining and tourism. However future changes to rainfall regimes remain uncertain due to the inability of Global Climate Models to adequately capture the tropical weather/climate processes that are known to be important for this region. Compounding this is the brevity of the instrumental rainfall record for the MNW, which is unlikely to represent the full range of climatic variability. One avenue for addressing this issue (the focus of this paper) is to identify sources of paleoclimate information that can be used to reconstruct a plausible pre-instrumental rainfall history for the MNW. Adopting this approach we find that, even in the absence of local sources of paleoclimate data at a suitable temporal resolution, remote paleoclimate records can resolve 25% of the annual variability observed in the instrumental rainfall record. Importantly, the 507-year rainfall reconstruction developed using the remote proxies displays longer and more intense wet and dry periods than observed during the most recent 100 years. For example, the maximum number of consecutive years of below (above) average rainfall is 90% (40%) higher in the rainfall reconstruction than during the instrumental period. Further, implications for flood and drought risk are studied via a simple GR1A rainfall runoff model, which again highlights the likelihood of extremes greater than that observed in the limited instrumental record, consistent with previous paleoclimate studies elsewhere in Australia. Importantly, this research can assist in informing climate related risks to infrastructure, agriculture and mining, and the method can readily be applied to other regions in the MNW and beyond.

  1. Vegetation - Central Mojave Desert [ds166

    Data.gov (United States)

    California Natural Resource Agency — The Department of Defense and the other desert managers are developing and organizing scientific information needed to better manage the natural resources of the...

  2. Microbial ecology of hot desert edaphic systems.

    Science.gov (United States)

    Makhalanyane, Thulani P; Valverde, Angel; Gunnigle, Eoin; Frossard, Aline; Ramond, Jean-Baptiste; Cowan, Don A

    2015-03-01

    A significant proportion of the Earth's surface is desert or in the process of desertification. The extreme environmental conditions that characterize these areas result in a surface that is essentially barren, with a limited range of higher plants and animals. Microbial communities are probably the dominant drivers of these systems, mediating key ecosystem processes. In this review, we examine the microbial communities of hot desert terrestrial biotopes (including soils, cryptic and refuge niches and plant-root-associated microbes) and the processes that govern their assembly. We also assess the possible effects of global climate change on hot desert microbial communities and the resulting feedback mechanisms. We conclude by discussing current gaps in our understanding of the microbiology of hot deserts and suggest fruitful avenues for future research. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. In vitro germination of desert rose varieties(

    OpenAIRE

    Tatiane Lemos Varella; Gizelly Mendes Silva; Kaliane Zaira Camacho Maximiliano da Cruz; Andréia Izabel Mikovski; Josué Ribeiro da Silva Nunes; Ilio Fealho Carvalho; Maurecilne Lemes Silva

    2015-01-01

    The drought stress resistance is a characteristic of the desert rose and its estimable beauty flowers, which gave it great relevance in the ornamental market. However, the desert rose production and germination is hampered by possible sterility of their male and female flowers and frequent problems in pollination, so the tissue culture is a promising alternative to the propagation of these plants. This study aimed to evaluate the effect of gibberellic acid on four commercial varieties of dese...

  4. Disturbance and Plant Succession in the Mojave and Sonoran Deserts of the American Southwest

    Directory of Open Access Journals (Sweden)

    Scott R. Abella

    2010-03-01

    Full Text Available Disturbances such as fire, land clearing, and road building remove vegetation and can have major influences on public health through effects on air quality, aesthetics, recreational opportunities, natural resource availability, and economics. Plant recovery and succession following disturbance are poorly understood in arid lands relative to more temperate regions. This study quantitatively reviewed vegetation reestablishment following a variety of disturbances in the Mojave and Sonoran Deserts of southwestern North America. A total of 47 studies met inclusion criteria for the review. The time estimated by 29 individual studies for full reestablishment of total perennial plant cover was 76 years. Although long, this time was shorter than an estimated 215 years (among 31 individual studies required for the recovery of species composition typical of undisturbed areas, assuming that recovery remains linear following the longest time since disturbance measurement made by the studies.

  5. Coupled Environmental Processes and Long-term Performance of Landfill Covers in the northern Mojave Desert

    Energy Technology Data Exchange (ETDEWEB)

    David Shafer; Michael Young; Stephen Zitzer; Eric McDonald; Todd Caldwell

    2004-05-12

    Evapotransiration (ET) covers have gained widespread acceptance as a closure feature for waste disposal sites, particularly in the arid and semi-arid regions of the southwestern U.S. But as landforms, ET covers are subject to change over time because of processes such as pedogenesis, hydrologic processes, vegetation establishment and change, and biological processes. To better understand the effects of coupled process changes to ET covers, a series of four primary analog sites in Yucca Flat on the Nevada Test Site, along with measurements and observations from other locations in the Mojave Desert, were selected to evaluate changes in ET covers over time. The analog sites, of varying ages, were selected to address changes in the early post-institutional control period, the 1,000-year compliance period for disposal of low-level and mixed low-level waste, and the 10,000-year compliance period for transuranic waste sites.

  6. Coupled Environmental Processes and Long-term Performance of Landfill Covers in the northern Mojave Desert

    International Nuclear Information System (INIS)

    David Shafer; Michael Young; Stephen Zitzer; Eric McDonald; Todd Caldwell

    2004-01-01

    Evapotransiration (ET) covers have gained widespread acceptance as a closure feature for waste disposal sites, particularly in the arid and semi-arid regions of the southwestern U.S. But as landforms, ET covers are subject to change over time because of processes such as pedogenesis, hydrologic processes, vegetation establishment and change, and biological processes. To better understand the effects of coupled process changes to ET covers, a series of four primary analog sites in Yucca Flat on the Nevada Test Site, along with measurements and observations from other locations in the Mojave Desert, were selected to evaluate changes in ET covers over time. The analog sites, of varying ages, were selected to address changes in the early post-institutional control period, the 1,000-year compliance period for disposal of low-level and mixed low-level waste, and the 10,000-year compliance period for transuranic waste sites

  7. Carbon, hydrogen oxygen isotope studies on imbedded old tree ring and paleoclimate reconstruction

    International Nuclear Information System (INIS)

    Sun Yanrong; Mu Zhiguo; Cui Haiting

    2002-01-01

    Tree ring is a kind of natural archives, on which the isotopic analysis is important to study global climate and environmental change. The authors mainly provide a comprehensive introduction to the fractionation models of carbon, hydrogen and oxygen isotope in plants, their research technique and the extract methods from cellulose. That results show isotopic tracer can record the message of climatic variation and has become a powerful tool for paleoclimate reconstruction and for the modern environment changing research. Especially studying on PAGES. the cellulose isotopic analyses of imbedded old tree ring have become the mainly quantitative means of environmental evolvement. In addition, China is a typical monsoon country, research in tree ring stable isotope seasonal variation can give a lot of important information on that. Up to now, the research techniques and works on tree ring in China are still in its earlier stage, and remain many limitations. It needs further accumulate basic research materials, intensity regional contrast and intercross studies on relative subjects

  8. The use of Sphagnum cellulose oxygen isotope ratios in ombrotrophic peatlands as a proxy for paleoclimate.

    Science.gov (United States)

    Taylor, M.; Pendall, E.; Jackson, S.; Booth, R. K.; Nichols, J. E.; Huang, Y.

    2006-12-01

    Developing proxies for discerning paleoclimate that are independent of the pollen record can provide insight into various aspects of climate variability and improve confidence in the interpretation of climate-vegetation interactions. To date, proxies including plant macrofossils, humification indices, testate amoebae, and ratios of n-alkane abundances have been used to infer past climate variability from temperate ombrotrophic peatlands in upper Midwestern North America. These proxies are used to infer past changes in surface-moisture conditions, which in ombrotrophic peatlands is primarily a function of precipitation and temperature. This study investigates the potential uses of stable oxygen isotopes to complement hydrologic proxies. δ18O of surface water and Sphagnum moss cellulose from bogs throughout North America indicates a correlation between average growing season temperatures and δ18O-values. The existence of a modern temperature signal in moss cellulose suggests that δ18O-derived records will not only complement paleohydrological records, but also help assess relative changes in precipitation and temperature. Humification and testate amoebae data from two cores taken from Minden and Irwin Smith Bogs in central and northeastern Michigan have recorded several extreme drought events during the Holocene, including one at 1000 YBP. Comparison of δ18O-values of picked Sphagnum remains to down-core humification and testate amoebae data suggest good temporal correspondence, with the δ18O-values around 1000 YBP indicating a warmer growing season.

  9. Rodent burrows in late Pleistocene paleosols at Korean Palaeolithic sites and their implications for paleoclimate changes

    Science.gov (United States)

    Lim, H.; Park, S.; Lee, J.; Lee, Y.

    2013-12-01

    Rodent burrows are commonly found at many Paleolithic archaeological sites in Korea. They are nearly straight in horizontal view and gently inclined in lateral view. Burrow diameters are mostly 7 - 10cm, and burrow length may reach a few meters. Vertical penetration depths are generally about 1 m from the surface, and the thickness of the burrow-bearing layer is about 1-2 m. Although no remains (bones, teeth, claws, and coprolites) were found within burrows, they are interpreted to have been produced by rodent-like mammals (probably ground squirrels) based on the size and architecture. According to the previous study, the age of these burrows was constrained to be between ca. 40,000 and 25,000 yr BP by tephrochronology, radiocarbon and optically stimulated luminescence dating results (Lim et al., 2007). However, little is known about the reason why these burrows have disappeared after late Pleistocene time. For this question, two explanations can be considered: extinction or migration. Since same kinds of burrows are still found in the high-latitude regions, such as Mongolia and North America, the possibility of extinction can be ruled out. Therefore, migration seems to be the most likely explanation. Our results show that the destruction of habitat caused by climate change during this period is the main reason for the northward migration of burrowing animals. This study suggests that rodent burrows found in the late Pleistocene paleosols can provide useful information on paleoclimate and paleoenvironmental changes.

  10. Late Quaternary history of the Atacama Desert

    Science.gov (United States)

    Latorre, Claudio; Betancourt, Julio L.; Rech, Jason A.; Quade, Jay; Holmgren, Camille; Placzek, Christa; Maldonado, Antonio; Vuille, Mathias; Rylander, Kate A.; Smith, Mike; Hesse, Paul

    2005-01-01

    Of the major subtropical deserts found in the Southern Hemisphere, the Atacama Desert is the driest. Throughout the Quaternary, the most pervasive climatic influence on the desert has been millennial-scale changes in the frequency and seasonality of the scant rainfall, and associated shifts in plant and animal distributions with elevation along the eastern margin of the desert. Over the past six years, we have mapped modern vegetation gradients and developed a number of palaeoenvironmental records, including vegetation histories from fossil rodent middens, groundwater levels from wetland (spring) deposits, and lake levels from shoreline evidence, along a 1200-kilometre transect (16–26°S) in the Atacama Desert. A strength of this palaeoclimate transect has been the ability to apply the same methodologies across broad elevational, latitudinal, climatic, vegetation and hydrological gradients. We are using this transect to reconstruct the histories of key components of the South American tropical (summer) and extratropical (winter) rainfall belts, precisely at those elevations where average annual rainfall wanes to zero. The focus has been on the transition from sparse, shrubby vegetation (known as the prepuna) into absolute desert, an expansive hyperarid terrain that extends from just above the coastal fog zone (approximately 800 metres) to more than 3500 metres in the most arid sectors in the southern Atacama.

  11. HIGH FOLIAR NITROGEN IN DESERT SHRUBS: AN IMPORTANT ECOSYSTEM TRAIT OR DEFECTIVE DESERT DOCTRINE?

    Science.gov (United States)

    Nitrogen concentrations in green and senesced leaves of perennial desert shrubs were compiled from a worldwide literature search to test the validity of the doctrine that desert shrubs produce foliage and leaf litter much richer in nitrogen than that in the foliage of plants from...

  12. Southwestern Power Administration Annual Report 2008

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-12-01

    Dear Secretary Chu, I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2008. In FY 2008, Southwestern delivered over 7.3 billion kilowatt-hours of energy to its wholesale customers – nearly 31% more than average due to numerous record rainfall amounts in the southwest region. These record amounts produced revenues which exceeded the average annual revenue requirement by nearly $20 million and resulted in over $200 million in economic benefits to the region. Yet even as Southwestern exceeded its goals of marketing and delivering Federal hydroelectric power to our customers, we stayed focused on safety, security, and reliability. For example, we maintained our nearly 1,400 miles of high-voltage transmission lines, substations, and communications sites while achieving a Recordable Accident Frequency Rate of 0.0, a record that reflects Southwestern’s safety achievement of no recordable injuries for every 200,000 hours worked. We kept our rights-of-way secure from vegetation and other obstacles, work that not only supports our mission but also promotes reliability of the regional and National grid. We exceeded all North American Electric Reliability Corporation (NERC) Control Performance Standards (CPS- 1 and CPS-2), and maintained regulation and reserve obligations and reactive reserve margins to ensure the reliability of the bulk electric system, even during extended periods of restricted hydro operations due to unusually high project inflows. Finally, we continued our partnerships with the Department of Energy, the U.S. Army Corps of Engineers, our customers, and other Federal power stakeholders, partnerships that are vital to our continued success in marketing and delivering carbon-free, renewable, and domestically produced energy to our customers and to the Nation. Sincerely, Jon Worthington Administrator

  13. Southwestern Institute of Physics annual report 2001

    International Nuclear Information System (INIS)

    2002-01-01

    In the year 2001, significant progresses in the engineering construction of the HL-2A tokamak were made at the Southwestern Institute of Physics (SWIP). At the same time, the research projects from Nuclear Energy Development Foundation, the National Defense Basic Research Foundation and the National Science Foundation of China were completely fulfilled. In addition 283 papers and reports were contributed, among them, 67 are included in the Annual Report

  14. Groundwater recharge in desert playas: current rates and future effects of climate change

    Science.gov (United States)

    McKenna, Owen P.; Sala, Osvaldo E.

    2018-01-01

    Our results from playas, which are topographic low areas situated in closed-catchments in drylands, indicated that projected climate change in Southwestern USA would have a net positive impact over runon and groundwater recharge beneath playas. Expected increased precipitation variability can cause up to a 300% increase in annual groundwater recharge beneath playas. This increase will overshadow the effect of decreased precipitation amount that could cause up to a 50% decrease in recharge beneath playas. These changes could have a significant impact on groundwater and carbon storage. These results are important given that groundwater resources in Southwestern USA continue to decline due to human consumption outpacing natural recharge of aquifers. Here, we report on groundwater recharge rates ranging from less than 1 mm to greater than 25 mm per year beneath desert playas. Playas located in larger and steeper catchments with finer-textured soils had the highest rates of recharge. Vegetation cover had no effect on recharge beneath playas. We modeled catchment runoff generation and found that the amount of runon a playa receives annually strongly correlated to the rate of groundwater recharge beneath that playa. Runon occurred during precipitation events larger than 20 mm and increased linearly with events above that threshold.

  15. Southwestern Power Administration Annual Report 2007

    Energy Technology Data Exchange (ETDEWEB)

    None

    2008-01-01

    “Renewable energy” isn’t just a catchphrase at Southwestern Power Administration (Southwestern). It describes the hydroelectric energy we market, and the energy that Southwestern’s employees bring to work every day, constantly challenging themselves to become more eff ective and effi cient in providing aff ordable, environmentally clean power to the American people. As Southwestern’s new Administrator, I have had the opportunity to view our operations from a fresh perspective, and I’m proud to share with you how a focus on continual improvement has been evident in accomplishments throughout the agency during fi scal year (FY) 2007. When the North American Electric Reliability Corporation (NERC) implemented new reliability standards, we met applicable implementation dates and exceeded NERC’s control performance standards throughout the year. When tasked with reducing the agency’s carbon footprint, we found ways to achieve an 8.7% reduction in energy intensity from last year without impacting our operational capabilities. And when faced with record-breaking infl ows into the reservoir projects from which we market power, we capitalized on the opportunity to provide customers with signifi cant quantities of supplemental energy. Our supplemental sales this year not only saved customers over $122 million, but increased Southwestern’s revenues -- a huge win-win for Southwestern’s ratepayers and the Nation’s taxpayers alike. Southwestern is proud of its role in protecting National and economic security by contributing to the diverse supply of domestically produced energy, operating and maintaining a safe and reliable transmission system, and ensuring good stewardship of our Nation’s water resources and environment. In FY 2007, Southwestern continued to repay all power costs to the American taxpayers by marketing and delivering approximately 5.6 billion kilowatthours of hydropower at cost-based rates to customers in our six-state region. This energy

  16. Historic distribution and challenges to bison recovery in the northern Chihuahuan Desert

    Science.gov (United States)

    List, Rurik; Ceballos, Gerardo; Curtin, Charles; Gogan, Peter J.; Pacheco, Jesus; Truett, Joe

    2007-01-01

    Ecologists and conservationists have long assumed that large grazers, including bison (Bison bison), did not occur in post-Pleistocene southwestern North America. This perception has been influential in framing the debate over conservation and land use in the northern Chihuahuan Desert. The lack of an evolutionary history of large grazers is being used to challenge the validity of ranching as a conservation strategy and to limit the protection and reintroduction of bison as a significant component of desert grassland ecosystems. Archeological records and historical accounts from Mexican archives from AD 700 to the 19th century document that the historic range of the bison included northern Mexico and adjoining areas in the United States. The Janos-Hidalgo bison herd, one of the few free-ranging bison herds in North America, has moved between Chihuahua, Mexico, and New Mexico, United States, since at least the 1920s. The persistence of this cross-border bison herd in Chihuahuan Desert grasslands and shrublands demonstrates that the species can persist in desert landscapes. Additional lines of evidence include the existence of grazing-adapted grasslands and the results of experimental studies that document declines in vegetation density and diversity following the removal of large grazers. The Janos-Hidalgo herd was formed with animals from various sources at the turn of the 19th century. Yet the future of the herd is compromised by differing perceptions of the ecological and evolutionary role of bison in the Desert Grasslands of North America. In Mexico they are considered native and are protected by federal law, whereas in New Mexico, they are considered non-native livestock and therefore lack conservation status or federal protection. Evidence written in Spanish of the presence of bison south of the accepted range and evidence from the disciplines of archaeology and history illustrate how differences in language and academic disciplines, in addition to

  17. Sonoran Desert winter annuals affected by density of red brome and soil nitrogen

    Science.gov (United States)

    Salo, L.F.; McPherson, G.R.; Williams, D.G.

    2005-01-01

    Red brome [Bromus madritensis subsp. rubens (L.) Husn.] is a Mediterranean winter annual grass that has invaded Southwestern USA deserts. This study evaluated interactions among 13 Sonoran Desert annual species at four densities of red brome from 0 to the equivalent of 1200 plants ma??2. We examined these interactions at low (3 I?g) and high (537 I?g NO3a?? g soila??1) nitrogen (N) to evaluate the relative effects of soil N level on survival and growth of native annuals and red brome. Red brome did not affect emergence or survival of native annuals, but significantly reduced growth of natives, raising concerns about effects of this exotic grass on the fecundity of these species. Differences in growth of red brome and of the three dominant non nitrogen-fixing native annuals at the two levels of soil N were similar. Total species biomass of red brome was reduced by 83% at low, compared to high, N levels, whereas that of the three native species was reduced by from 42 to 95%. Mean individual biomass of red brome was reduced by 87% at low, compared to high, N levels, whereas that of the three native species was reduced by from 72 to 89%.

  18. A lacustrine record from Lop Nur, Xinjiang, China: Implications for paleoclimate change during Late Pleistocene

    Science.gov (United States)

    Chao, L.; Zicheng, P.; Dong, Y.; Weiguo, L.; Zhaofeng, Z.; Jianfeng, H.; Chenlin, C.

    2009-01-01

    Climate variability during the Late Pleistocene is studied from the proxies in core CK-2 drilled from the Luobei Depression (91??03???E, 40??47???N), Lop Nur in the eastern Tarim Basin, Xinjiang, China. Geophysical and geochemical properties, including magnetic susceptibility, granularity, chroma, carbonate content, loss on ignition and trace elements, have been determined to reconstruct the environmental evolution of the area during 32-9 ka BP. The chronology is established by uranium-thorium disequilibrium dating techniques. Our data suggest four paleoclimate stages, indicating glacial variations between cold-humid and warm-arid environments. A period of extreme humidity occurred during 31,900-19,200 yr BP is attributed the last glacial maximum (LGM). The period was followed by a warm-arid episode during 19,200-13,500 yr BP. Then a cold-humid interval during 13,500-12,700 yr BP may correspond to another cooling phases at high latitudes of the Northern Hemisphere. The last stage from 12,700 to 9000 yr BP has a trend that the climate turned warm and arid. The Lop Nur region is characterized by particularly humid stadials and arid interstadials. The climate variability in Lop Nur was constrained by global climate change because it is correlated with Dansgaard-Oeschger and Heinrich events, which were observed at the northern high latitudes. The synchroneity of the palaeoclimatic events suggested that cold air activity at the northern high latitudes was the most important factor that influenced the climate evolution in the Lop Nur region. A probable mechanism that involves the migration of westerly winds is proposed to interpret this synchroneity. ?? 2008 Elsevier Ltd.

  19. Characteristics of Intracrater Thermal Anomalies in Southwestern Margaritifer Terra

    Science.gov (United States)

    McDowell, M. L.; Hamilton, V. E.

    2005-03-01

    We use thermophysical properties, albedo, short wavelength emissivity, composition, and geomorphology to understand the formation of anomalously warm intracrater deposits in southwestern Margaritifer Terra.

  20. Soil texture drives responses of soil respiration to precipitation pulses in the sonoran desert: Implications for climate change

    Science.gov (United States)

    Cable, J.M.; Ogle, K.; Williams, D.G.; Weltzin, J.F.; Huxman, T. E.

    2008-01-01

    Climate change predictions for the desert southwestern U.S. are for shifts in precipitation patterns. The impacts of climate change may be significant, because desert soil processes are strongly controlled by precipitation inputs ('pulses') via their effect on soil water availability. This study examined the response of soil respiration-an important biological process that affects soil carbon (C) storage-to variation in pulses representative of climate change scenarios for the Sonoran Desert. Because deserts are mosaics of different plant cover types and soil textures-which create patchiness in soil respiration-we examined how these landscape characteristics interact to affect the response of soil respiration to pulses. Pulses were applied to experimental plots of bare and vegetated soil on contrasting soil textures typical of Sonoran Desert grasslands. The data were analyzed within a Bayesian framework to: (1) determine pulse size and antecedent moisture (soil moisture prior to the pulse) effects on soil respiration, (2) quantify soil texture (coarse vs. fine) and cover type (bare vs. vegetated) effects on the response of soil respiration and its components (plant vs. microbial) to pulses, and (3) explore the relationship between long-term variation in pulse regimes and seasonal soil respiration. Regarding objective (1), larger pulses resulted in higher respiration rates, particularly from vegetated fine-textured soil, and dry antecedent conditions amplified respiration responses to pulses (wet antecedent conditions dampened the pulse response). Regarding (2), autotrophic (plant) activity was a significant source (???60%) of respiration and was more sensitive to pulses on coarse- versus fine-textured soils. The sensitivity of heterotrophic (microbial) respiration to pulses was highly dependent on antecedent soil water. Regarding (3), seasonal soil respiration was predicted to increase with both growing season precipitation and mean pulse size (but only for pulses

  1. Chemical mass balance source apportionment of fine and PM10 in the Desert Southwest, USA

    Directory of Open Access Journals (Sweden)

    Andrea L. Clements

    2016-03-01

    Full Text Available The Desert Southwest Coarse Particulate Matter Study was undertaken in Pinal County, Arizona, to better understand the origin and impact of sources of fine and coarse particulate matter (PM in rural, arid regions of the U.S. southwestern desert. The desert southwest experiences some of the highest PM10 mass concentrations in the country. To augment previously reported results, 6-week aggregated organic speciation data that included ambient concentrations of n-alkanes, polycyclic aromatic hydrocarbons, organic acids, and saccharides were used in chemical mass balance modeling (CMB. A set of re-suspended soil samples were analyzed for specific marker species to provide locally-appropriate source profiles for the CMB analysis. These profiles, as well as previously collected plant and fungal spore profiles from the region, were combined with published source profiles for other relevant sources and used in the CMB analysis. The six new region-specific source profiles included both organic and inorganic species for four crustal material sources, one plant detritus source, and one fungal spore source.Results indicate that up to half of the ambient PM2.5 was apportioned to motor vehicles with the highest regional contribution observed in the small urban center of Casa Grande. Daily levels of apportioned crustal material accounted for up to 50% of PM2.5 mass with the highest contributions observed at the sites closest to active agricultural areas. Apportioned secondary PM, biomass burning, and road dust typically contributed less than 35% as a group to the apportioned PM2.5 mass. Crustal material was the primary source apportioned to PM10 and accounted for between 50–90% of the apportioned mass. Of the other sources apportioned to PM10, motor vehicles and road dust were the largest contributors at the urban and one of the rural sites, whereas road dust and meat cooking operations were the largest contributors at the other rural site.

  2. Desert basins of the Southwest

    Science.gov (United States)

    Leake, Stanley A.; Konieczki, Alice D.; Rees, Julie A.H.

    2000-01-01

    Ground water is among the Nation’s most important natural resources. It provides drinking water to urban and rural communities, supports irrigation and industry, sustains the flow of streams and rivers, and maintains riparian and wetland ecosystems. In many areas of the Nation, the future sustainability of ground-water resources is at risk from overuse and contamination. Because ground-water systems typically respond slowly to human actions, a long-term perspective is needed to manage this valuable resource. This publication is one in a series of fact sheets that describe ground-water-resource issues across the United States, as well as some of the activities of the U.S. Geological Survey that provide information to help others develop, manage, and protect ground-water resources in a sustainable manner. Ground-water resources in the Southwest are among the most overused in the United States. Natural recharge to aquifers is low and pumping in many areas has resulted in lowering of water tables. The consequences of large-scale removal of water from storage are becoming increasingly evident. These consequences include land subsidence; loss of springs, streams, wetlands and associated habitat; and degradation of water quality. Water managers are now seeking better ways of managing ground-water resources while looking for supplemental sources of water. This fact sheet reviews basic information on ground water in the desert basins of the Southwest. Also described are some activities of the U.S. Geological Survey (USGS) that are providing scientific information for sustainable management of ground-water resources in the Southwest. Ground-water sustainability is defined as developing and using ground water in a way that can be maintained for an indefinite time without causing unacceptable environmental, economic, or social consequences.

  3. Oxalosis in wild desert tortoises, Gopherus agassizii

    Science.gov (United States)

    Jacobson, Elliott R.; Berry, Kristin H.; Stacy, Brian; Huzella, Louis M.; Kalasinsky, Victor F.; Fleetwood, Michelle L.; Mense, Mark G.

    2009-01-01

    We necropsied a moribund, wild adult male desert tortoise (Gopherus agassizii) with clinical signs of respiratory disease and elevated plasma biochemical analytes indicative of renal disease (blood urea nitrogen [415 mg/dl], uric acid [11.8 mg/dl], sodium >180 mmol/l] and chloride [139 mmol/l]). Moderate numbers of birefringent oxalate crystals, based on infrared and electron microscopy, were present within renal tubules; small numbers were seen in colloid within thyroid follicles. A retrospective analysis of 66 additional cases of wild desert tortoises was conducted to determine whether similar crystals were present in thyroid and kidney. The tortoises, from the Mojave and Sonoran deserts, were necropsied between 1992 and 2003 and included juveniles and adults. Tortoises were classified as healthy (those that died due to trauma and where no disease was identified after necropsy and evaluation by standard laboratory tests used for other tortoises) or not healthy (having one or more diseases or lesions). For all 67 necropsied tortoises, small numbers of crystals of similar appearance were present in thyroid glands from 44 of 54 cases (81%) and in kidneys from three of 65 cases (5%). Presence of oxalates did not differ significantly between healthy and unhealthy tortoises, between age classes, or between desert region, and their presence was considered an incidental finding. Small numbers of oxalate crystals seen within the kidney of two additional tortoises also were considered an incidental finding. Although the source of the calcium oxalate could not be determined, desert tortoises are herbivores, and a plant origin seems most likely. Studies are needed to evaluate the oxalate content of plants consumed by desert tortoises, and particularly those in the area where the tortoise in renal failure was found.

  4. Desertification and its effect on the erosion of vegetation in the south-western region of Saudi Arabia.

    Science.gov (United States)

    Abd El-Salam, Magda Magdy; Elhakem, Abeer Hamdy

    2016-03-01

    This study was conducted in Jazan region of south-western Saudi Arabia. Vegetation cover, frequency, abundance and soil characteristics were analysed at three locations with different quantitative and descriptive vegetation characteristics. Plant species were classified into three primary communities dominated by Salvadora persic, Acacia tortilis and Ziziphus spini-Christi. The results indicated that the distribution of plant species is controlled by soil characteristics. Very limited water resources are also limiting factor in vegetation growth. Among the three studied sites, desert and coastal environments are affected by desertification. Rehabilitation of the degraded lands requires collaborative efforts and support from the different related governmental sectors. Ecological conservation and sustainable development must be adopted as tools of rehabilitation.

  5. Jojoba could stop the desert creep

    Energy Technology Data Exchange (ETDEWEB)

    1982-03-25

    The Sahara desert is estimated to be expanding at a rate of 5km a year. The Sudanese government is experimenting with jojoba in six different regions as the bush has the potential to stop this ''desert creep''. The plant, a native to Mexico, is long known for its resistance to drought and for the versatile liquid wax that can be extracted from its seeds. It is estimated that one hectare of mature plants could produce 3000 kg of oil, currently selling at $50 per litre, and so earn valuable foreign currency.

  6. CAMEL REARING IN CHOLISTAN DESERT OF PAKISTAN

    OpenAIRE

    I. ALI, M. SHAFIQ CHAUDHRY1 AND U. FAROOQ

    2009-01-01

    The camel is one of the typical and the best adopted animals of the desert, capable of enduring thirst and hunger for days and is the most patient of land animals. For desert nomads of Pakistani Cholistan, it is a beloved companion, a source of milk and meat, transport facility provider and a racing/dancing animal, thus, playing an important role in the socioeconomic uplift of the local community. Camels of Marrecha or Mahra breed are mainly used for riding and load carrying but may be traine...

  7. The paleo-climate change of Chaidam Basin during the last 2.85 Ma recorded by gamma-ray logging

    International Nuclear Information System (INIS)

    Chen Ye; Yuan Linwang; Liu Zechun

    2000-01-01

    The author deals with mainly the aspect of paleo-climate change of the basin. The approach used for the study consisted of (1) establishing the paleo-climate curve of the basin according to the climate indices, including the spore-pollen statistics, carbonate content and δ 18 O, obtained from the samples of the 760 m continuously-cored exploration holes sited in the basin, (2) comparing the paleo-climate curve with the natural gamma-logs of the same exploration holes, and (3) determining the paleo-climatic changes in the last 2.85 Ma on the basis of detailed geochronological calculations. These results are extremely important for comparison with the δ 18 O-based climate curve derived from the ODP659 in the Atlantic Ocean and with the cycles of paleosol in the Chinese loess

  8. Transformational Leadership and Teacher Motivation in Southwestern Arizona High Schools

    Science.gov (United States)

    Reynolds, Catherine L.

    2009-01-01

    The purpose of this study was to explore the relationship between transformational leadership and teacher motivation in Southwestern Arizona high schools. Teachers in a school district in Southwestern Arizona comprised of high schools were surveyed using two instruments, Leithwood and Jantzi's (1998) The Leadership and Management of Schools in…

  9. Some lessons in artificial regeneration from southwestern Oregon.

    Science.gov (United States)

    William I. Stein

    1955-01-01

    Natural reproduction has often proved undependable for restocking cutovers and burns in the mixed-conifer forest types of southwestern Oregon. These types, covering 6,000 square miles of productive forest land in the five southwestern Oregon counties, are composed of many species--principally Douglas fir, Pseudotsuga menziesii (Mirb.) Franco;...

  10. Late Pliocene Depositional History and Paleoclimate Reconstructions of the Southwest Pacific

    Science.gov (United States)

    Royce, B.; Patterson, M. O.; Pietras, J.

    2017-12-01

    Drift deposits off the eastern margin of New Zealand are important archives for the paleoclimate and paleoceanographic history of the southwest Pacific. Ocean Drilling Program (ODP) Site 1123 is located on the North Chatham rise drift just North of the westerly wind driven Subtropical Front (STF) and provides a record of near continuous sediment deposition since the Miocene along the southwest Pacific deep western boundary current (DWBC). While the Miocene and Late Pleistocene portion of this record have been well studied, the Late Pliocene record is less well developed. Southern Ocean geological records demonstrate that Late Pliocene cooling is the transient time bracketing the warmer than present Early Pliocene and bipolar glaciation at 2.7 Ma. A newly developed, robust, and astronomically tuned long-term record of benthic δ13C from ODP Site 1123 spanning the Early to Late Pliocene implies a reduction in Southern Ocean ventilation and lowering of preformed values from waters sourced along the Antarctic margin during the Late Pliocene. Thus, Late Pliocene Southern Hemisphere cooling and sea ice expansion may have drastically reduced outgassing and increased the burial of heat into the deep ocean. South Atlantic records off the west coast of Africa demonstrate an increase in the flux of iron to the open ocean during this time potentially enhancing surface ocean productivity and providing an additional cooling mechanism. Currently, atmospheric transport of dust to the Southern Ocean is dominated by persistent mid-latitude circumpolar westerly winds; this is particularly relevant for dust sourced from New Zealand. The Late Pliocene to Early Pleistocene uplift of the North Island axial ranges and South Island southern alps potentially provided a greater amount of not only sediment to the deep ocean, but also wind blow dust to the Pacific sector of the Southern Ocean. We will present a detailed high-resolution sedimentological study on the development of the Chatham

  11. Paleoclimate Signals and Age Distributions from 41 Public Water Works in the Netherlands

    Science.gov (United States)

    Broers, H. P.; Weert, J. D.; Sültenfuß, J.; Aeschbach, W.; Vonhof, H.; Casteleijns, J.

    2015-12-01

    paleoclimate signals, with a clear relations between NGT (ranging from 2,8 -9 °C), 4He (up to 3.3E-6 cc STP/g) and 18O (range from -8.5—5.5‰). Moreover, ¾ ratios of these graben waters suggest an influx of He from mantle origin.

  12. A Record of Holocene Paleoclimate Evolution from Robertson Bay, Victoria Land, Antarctica

    Science.gov (United States)

    Riesselman, C. R.; Truax, O.; Wilson, G. S.; Parker, R. L.; Yoo, K. C.; Lee, J. I.; Levy, R. H.; Mckay, R. M.

    2017-12-01

    Regionally representative records of how Antarctica responded to the transition from the Last Glacial Maximum into the Holocene are an essential component of understanding the processes by which the Antarctic cryosphere responds to a changing climate. Here, we present a high-resolution record of Holocene Antarctic paleoclimate evolution from a previously unstudied section of the Victoria Land margin. In 2015 the Korea Polar Research Institute collected a 571 cm sediment core, GC57, from Robertson Bay, a protected embayment west of Cape Adare and adjacent to the outlet glaciers of the Transantarctic Mountains. Using diatom assemblages, bulk sediment geochemistry, and the magnetic properties of GC57, we aim to reconstruct the response of the East Antarctic Ice Sheet to warming associated with deglaciation and the Holocene climatic optima at the interface between the Ross Sea and the Southern Ocean. Our multiproxy approach allows us to study sea ice extent, seasonality, ocean stratification and circulation, and primary productivity from the mid-Holocene (7,400 14C year BP) to the present. A sea-ice associated diatom assemblage indicative of summer sea surface temperatures below 0˚C dominates the basal section of GC57. Although diatoms are well preserved, the unit is characterized by low wt% biogenic silica (average 9%) and a high concentration of magnetic minerals, indicating that biogenic production persisted despite substantial terrigenous input into the bay. A rapid transition at 4708 14C yr BP is identified by a steep increase in wt% BSi (average 13%), a decrease in magnetic minerals, and a subtle assemblage change towards sea-ice associated diatoms with slightly warmer temperature tolerances. The novel ramped pyrolosis 14C dating methodology allows us to date the carbon fixed concurrent with deposition and generate a robust age model for GC57 with an accuracy previously difficult to achieve given the uncertainties associated with dating bulk acid insoluble

  13. Paleoclimate cycles and tectonic controls on fluvial, lacustrine, and eolian strata in upper Triassic Chinle Formation, San Juan basin

    Energy Technology Data Exchange (ETDEWEB)

    Dubiel, R.F. (Geological Survey, Denver, CO (USA))

    1989-09-01

    Sedimentologic study of the Upper Triassic Chinle Formation in the San Juan basin (SJB) indicates that Late Triassic paleoclimate and tectonic movements influenced the distribution of continental lithofacies. The Shinarump, Monitor Butte, and Petrified Forest Members in the lower part of the Chinle consist of complexly interfingered fluvial, floodplain, marsh, and lacustrine rocks; the Owl Rock and Rock Point Members in the upper part consists of lacustrine-basin and eolian sandsheet strata. Facies analysis, vertebrate and invertebrate paleontology, and paleoclimate models demonstrate that the Late Triassic was dominated by tropical monsoonal circulation, which provided abundant precipitation interspersed with seasonally dry periods. Owl Rock lacustrine strata comprise laminated limestones that reflect seasonal monsoonal precipitation and larger scale, interbedded carbonates and fine-grained clastics that represent longer term, alternating wet and dry climatic cycles. Overlying Rock Point eolian sand-sheet and dune deposits indicate persistent alternating but drier climatic cyclicity. Within the Chinle, upward succession of lacustrine, alternating lacustrine/eolian sand-sheet, and eolian sand-sheet/dune deposits reflects an overall decrease in precipitation due to the northward migration of Pangaea out of low latitudes dominated by monsoonal circulation.

  14. Gopherus Agassizii (Desert Tortoise). Predation/Mountain Lions (Pre-Print)

    Energy Technology Data Exchange (ETDEWEB)

    Paul D. Greger and Philip A. Medica

    2009-01-01

    sized Mountain Lion. By comparison, a 2 year old male Mountain Lion salvaged on NTS had an upper intercanine bite width of 45 mm, and a 6 month old kitten measured 35mm respectively. The Mountain Lion (Puma concolor) is the only predator that exists in southern Nevada that could possibly have a bite with a gap between its upper canine teeth that large (Murmann et al. 2006. J. Forensic Sci. 51:846-860). The appearance of the shell remains in Figure 1A is similar to that depicting Jaguar (Panthera onca) predation, on the Amazonian Tortoise (Geochelone denticulata) as illustrated by Emmons (1989. J. Herpetol. 23:311-314) with the majority of the carapace broken open and the plastron still intact. Predation of Desert Tortoises by Mountain Lions was also documented in 1993 in southern Arizona (Little Shipp Wash Plot), where 7 of 8 carcasses found were attributed to Mountain Lion predation (Averill-Murray et al. 2002. In. T.R.Van Devender [ed.], The Sonoran Desert Tortoise: Natural History, Biology, and Conservation, pp.109-134. University of Arizona Press and Arizona-Sonora Desert Museum, Tucson, Arizona). Similarly, predation by a Mountain Lion has been reported on the Argentine Tortoise (Chelonoidis chilensis) in Argentina (Acosta et al. 2004. Herpetol. Review 35:53-54), and a Mountain Lion kitten was observed to kill and consume a portion of the carapace of a Texas Tortoise (Gopherus berlandieri) in west Texas (Adams et al. 2006. Southwestern Nat. 51:581-581). Over the past 45 years this Desert Tortoise population has been monitored yearly, with no prior evidence of predation to tortoises within the fenced enclosures. On several occasions other predators such as Bobcats (Lynx rufus) have been observed within the study enclosures for as long as a week. Evidence of Kit Fox (Vulpes macrotus) sign has been observed on numerous occasions, and a Spotted Skunk (Spilogale putorius) and Longtail Weasels (Mustela frenata) have been captured and released (B.G. Maza, pers. comm

  15. Comparing Apples to Apples: Paleoclimate Model-Data comparison via Proxy System Modeling

    Science.gov (United States)

    Dee, Sylvia; Emile-Geay, Julien; Evans, Michael; Noone, David

    2014-05-01

    The wealth of paleodata spanning the last millennium (hereinafter LM) provides an invaluable testbed for CMIP5-class GCMs. However, comparing GCM output to paleodata is non-trivial. High-resolution paleoclimate proxies generally contain a multivariate and non-linear response to regional climate forcing. Disentangling the multivariate environmental influences on proxies like corals, speleothems, and trees can be complex due to spatiotemporal climate variability, non-stationarity, and threshold dependence. Given these and other complications, many paleodata-GCM comparisons take a leap of faith, relating climate fields (e.g. precipitation, temperature) to geochemical signals in proxy data (e.g. δ18O in coral aragonite or ice cores) (e.g. Braconnot et al., 2012). Isotope-enabled GCMs are a step in the right direction, with water isotopes providing a connector point between GCMs and paleodata. However, such studies are still rare, and isotope fields are not archived as part of LM PMIP3 simulations. More importantly, much of the complexity in how proxy systems record and transduce environmental signals remains unaccounted for. In this study we use proxy system models (PSMs, Evans et al., 2013) to bridge this conceptual gap. A PSM mathematically encodes the mechanistic understanding of the physical, geochemical and, sometimes biological influences on each proxy. To translate GCM output to proxy space, we have synthesized a comprehensive, consistently formatted package of published PSMs, including δ18O in corals, tree ring cellulose, speleothems, and ice cores. Each PSM is comprised of three sub-models: sensor, archive, and observation. For the first time, these different components are coupled together for four major proxy types, allowing uncertainties due to both dating and signal interpretation to be treated within a self-consistent framework. The output of this process is an ensemble of many (say N = 1,000) realizations of the proxy network, all equally plausible

  16. Divining Jordan's desert waters | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... in the area have a long history of being water-conservers, and the idea of using the ... Dr Abu-Jaber examined is covered by an ancient, volcanic rock called basalt. ... When a desert cloudburst drops rain on the area, the raindrops quickly roll ...

  17. Liquid Water Restricts Habitability in Extreme Deserts.

    Science.gov (United States)

    Cockell, Charles S; Brown, Sarah; Landenmark, Hanna; Samuels, Toby; Siddall, Rebecca; Wadsworth, Jennifer

    2017-04-01

    Liquid water is a requirement for biochemistry, yet under some circumstances it is deleterious to life. Here, we show that liquid water reduces the upper temperature survival limit for two extremophilic photosynthetic microorganisms (Gloeocapsa and Chroococcidiopsis spp.) by greater than 40°C under hydrated conditions compared to desiccated conditions. Under hydrated conditions, thermal stress causes protein inactivation as shown by the fluorescein diacetate assay. The presence of water was also found to enhance the deleterious effects of freeze-thaw in Chroococcidiopsis sp. In the presence of water, short-wavelength UV radiation more effectively kills Gloeocapsa sp. colonies, which we hypothesize is caused by factors including the greater penetration of UV radiation into hydrated colonies compared to desiccated colonies. The data predict that deserts where maximum thermal stress or irradiation occurs in conjunction with the presence of liquid water may be less habitable to some organisms than more extreme arid deserts where organisms can dehydrate prior to being exposed to these extremes, thus minimizing thermal and radiation damage. Life in extreme deserts is poised between the deleterious effects of the presence and the lack of liquid water. Key Words: Deserts-Extremophiles-Stress-High temperatures-UV radiation-Desiccation. Astrobiology 17, 309-318.

  18. Preventing desert locust plagues: optimizing management interventions

    NARCIS (Netherlands)

    Huis, van A.; Cressman, K.; Magor, J.I.

    2007-01-01

    Solitarious desert locusts, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), inhabit the central, arid, and semi-arid parts of the species¿ invasion area in Africa, the Middle East, and South-West Asia. Their annual migration circuit takes them downwind to breed sequentially where winter,

  19. Abiotic drivers of Chihuahuan Desert plant communities

    Science.gov (United States)

    Laura Marie Ladwig

    2014-01-01

    Within grasslands, precipitation, fire, nitrogen (N) addition, and extreme temperatures influence community composition and ecosystem function. The differential influences of these abiotic factors on Chihuahuan Desert grassland communities was examined within the Sevilleta National Wildlife Refuge, located in central New Mexico, U.S.A. Although fire is a natural...

  20. Reclaiming freshwater sustainability in the Cadillac Desert

    Science.gov (United States)

    Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H.W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

    2010-01-01

    Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%.

  1. Geology and geochemistry of the Atacama Desert.

    Science.gov (United States)

    Tapia, J; González, R; Townley, B; Oliveros, V; Álvarez, F; Aguilar, G; Menzies, A; Calderón, M

    2018-02-14

    The Atacama Desert, the driest of its kind on Earth, hosts a number of unique geological and geochemical features that make it unlike any other environment on the planet. Considering its location on the western border of South America, between 17 and 28 °S, its climate has been characterized as arid to hyperarid for at least the past 10 million years. Notably dry climatic conditions of the Atacama Desert have been related to uplift of the Andes and are believed to have played an important role in the development of the most distinctive features of this desert, including: (i) nitrates and iodine deposits in the Central Depression, (ii) secondary enrichment in porphyry copper deposits in the Precordillera, (iii) Li enrichment in salt flats of the Altiplano, and (iv) life in extreme habitats. The geology and physiography of the Atacama Desert have been largely shaped by the convergent margin present since the Mesozoic era. The geochemistry of surface materials is related to rock geochemistry (Co, Cr, Fe, Mn, V, and Zn), salt flats, and evaporite compositions in endorheic basins (As, B, and Li), in addition to anthropogenic activities (Cu, Mo, and Pb). The composition of surface water is highly variable, nonetheless in general it presents a circumneutral pH with higher conductivity and total dissolved solids in brines. Major water constituents, with the exception of HCO 3 - , are generally related to the increase of salinity, and despite the fact that trace elements are not well-documented, surface waters of the Atacama Desert are enriched in As, B, and Li when compared to the average respective concentrations in rivers worldwide.

  2. Solar energy development and aquatic ecosystems in the southwestern United States: potential impacts, mitigation, and research needs.

    Science.gov (United States)

    Grippo, Mark; Hayse, John W; O'Connor, Ben L

    2015-01-01

    The cumulative impacts of utility-scale solar energy facilities on aquatic ecosystems in the Southwestern United States are of concern, considering the many existing regional anthropogenic stressors. We review the potential impacts of solar energy development on aquatic habitat and biota. The greatest potential for impacts is related to the loss, fragmentation, or prolonged drying of ephemeral water bodies and drainage networks resulting from the loss of desert washes within the construction footprint of the facility. Groundwater-dependent aquatic habitat may also be affected by operational groundwater withdrawal in the case of water-intensive solar technologies. Solar panels have also been found to attract aquatic insects and waterbirds, potentially resulting in mortality. Avoiding construction activity near perennial and intermittent surface waters is the primary means of reducing impacts on aquatic habitats, followed by measures to minimize erosion, sedimentation, and contaminant inputs into waterways. Currently, significant data gaps make solar facility impact assessment and mitigation more difficult. Examples include the need for more regional and site-specific studies of surface-groundwater connectivity, more detailed maps of regional stream networks and riparian vegetation corridors, as well as surveys of the aquatic communities inhabiting ephemeral streams. In addition, because they often lack regulatory protection, there is also a need to develop valuation criteria for ephemeral waters based on their ecological and hydrologic function within the landscape. By addressing these research needs, we can achieve the goal of greater reliance on solar energy, while at the same time minimizing impacts on desert ecosystems.

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

    Science.gov (United States)

    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

  4. Cancer mortality and radioactive fallout in southwestern Utah

    International Nuclear Information System (INIS)

    Machado, S.G.; Land, C.E.; McKay, F.W.

    1987-01-01

    Cancer mortality was compared between a three-county region in southwestern Utah and the remainder of Utah in an investigation of reported excess cancer risks associated with residence in southwestern Utah during the period of above-ground nuclear tests at the Nevada Test Site. Because most of the fallout in southwestern Utah was deposited during 1953-1957, comparisons were limited to persons born before 1958, and deaths from leukemia and bone cancer during 1955-1980 and from other cancers during 1964-1980. There was no excess risk of cancer mortality in southwestern Utah, for single or grouped sites, with the single exception of leukemia which showed statistically significant odds ratios of 1.45 based on 62 deaths at all ages, and 2.84 based on nine deaths at ages 0-14. The finding for childhood leukemia was based on different time periods and geographic comparisons from those of two earlier studies in which no such excess was found. Mortality from all cancer sites combined was significantly lower in southwestern Utah than in the remainder of the state, even after adjustment for the higher proportion of (lower risk) Mormons in southwestern Utah. The present results, including the positive association for leukemia, are inconsistent with the high excess risks reported by Johnson (JAMA 1984;251:230-6) based on an interview survey of cancer incidence among long-term Mormon residents of southwestern Utah

  5. Aragonite-Calcite Inversion During Biogenic Carbonate Sampling: Considerations for Interpreting Isotopic Measurements in Paleoclimate Studies

    Science.gov (United States)

    Waite, A. J.; Swart, P. K.

    2011-12-01

    , suggests that the isotopic depletion is tied to the polymorphic inversion of aragonite to calcite, and not just random chance based on natural isotopic variability in the skeleton. There appears to be no relationship between the percent inversion and carbon isotopic composition. Elemental ratios also appear to remain stable during the heating and inversion process. The findings of this and published studies present, in many cases, conflicting views of the isotopic fractionation associated with inversion of aragonite to calcite. Discrepancies such as this likely result from subtle differences in sampling protocol related to instruments, drill bits, skeletal density, and possibly even laboratory conditions like temperature and humidity, further complicating our understanding and interpretation of such observations. Preliminary investigation suggests that altering milling conditions or wet milling may reduce the extent of alteration. Unfortunately, milling/drilling remains one of the only practical methods of sampling biogenic carbonates at a high resolution for paleoclimate work and, as such, caution should be taken in the interpretation of oxygen isotopic measurements from specimens of this nature.

  6. Radiatively-driven processes in forest fire and desert dust plumes

    Energy Technology Data Exchange (ETDEWEB)

    Weinzierl, Bernadett Barbara

    2008-07-01

    -volatile components and contain absorbing material. After regional-scale transport from the Sahara to South-western Europe, the volatile fraction in the dust plume did not significantly increase. The lofted forest fire plumes were found during ITOP at altitudes between 3 and 9 km above sea level (ASL), while the lofted desert dust plumes were found during SAMUM between 1 and 6 km ASL. The transition of the aerosol plumes to the free tropospheric background above and below the plumes was remarkably sharp and characterised by strong inversions. Within a height range of 200-300 m, the particle concentrations decreased by more than one order of magnitude. The results of plume dilution were evident only in the upper part of the lofted forest fire and desert dust plumes. The daily mean heating rates in the forest fire and desert dust plumes showed maximum values of {proportional_to}0.2 K day{sup -1} and {proportional_to}0.24 K day{sup -1}, respectively. Vertical profiles of the heating rate suggest that the processes caused by the interaction between the aerosol particles and the solar radiation stabilise the plume itself and decelerate plume dilution. Apparently, the aerosol in such plumes ages in an almost ''closed'' system, where suppressed entrainment of condensable gases from the surface inhibits particle nucleation and the formation of coated particles inside the plume. The processes described tend to extend the lifetime of the layer allowing the transport over long distances. (orig.)

  7. Hydroclimate variability in the low-elevation Atacama Desert over the last 2500 yr

    Science.gov (United States)

    Gayo, E. M.; Latorre, C.; Santoro, C. M.; Maldonado, A.; de Pol-Holz, R.

    2012-02-01

    Paleoclimate reconstructions reveal that Earth system has experienced sub-millennial scale climate changes over the past two millennia in response to internal/external forcing. Although sub-millennial hydroclimate fluctuations have been detected in the central Andes during this interval, the timing, magnitude, extent and direction of change of these events remain poorly defined. Here, we present a reconstruction of hydroclimate variations on the Pacific slope of the central Andes based on exceptionally well-preserved plant macrofossils and associated archaeological remains from a hyperarid drainage (Quebrada Maní, ∼21° S, 1000 m a.s.l.) in the Atacama Desert. During the late Holocene, riparian ecosystems and farming social groups flourished in the hyperarid Atacama core as surface water availability increased throughout this presently sterile landscape. Twenty-six radiocarbon dates indicate that these events occurred between 1050-680, 1615-1350 and 2500-2040 cal yr BP. Regional comparisons with rodent middens and other records suggest that these events were synchronous with pluvial stages detected at higher-elevations in the central Andes over the last 2500 yr. These hydroclimate changes also coincide with periods of pronounced SST gradients in the Tropical Pacific (La Niña-like mode), conditions that are conducive to significantly increased rainfall in the central Andean highlands and flood events in the low-elevation watersheds at inter-annual timescales. Our findings indicate that the positive anomalies in the hyperarid Atacama over the past 2500 yr represent a regional response of the central Andean climate system to changes in the global hydrological cycle at centennial timescales. Furthermore, our results provide support for the role of tropical Pacific sea surface temperature gradient changes as the primary mechanism responsible for climate fluctuations in the central Andes. Finally, our results constitute independent evidence for comprehending the

  8. Hydroclimate variability in the low-elevation Atacama Desert over the last 2500 years

    Science.gov (United States)

    Gayo, E. M.; Latorre, C.; Santoro, C. M.; Maldonado, A.; de Pol-Holz, R.

    2011-10-01

    Paleoclimate reconstructions reveal that Earth system has experienced sub-millennial scale climate changes over the past two millennia in response to internal/external forcing. Although sub-millennial hydroclimate fluctuations have been detected in the central Andes during this interval, the timing, magnitude, extent and direction of change of these events remain poorly defined. Here, we present a reconstruction of hydroclimate variations on the Pacific slope of the central Andes based on exceptionally well-preserved plant macrofossils and associated archaeological remains from a hyperarid drainage (Quebrada Maní, ~21° S, 1000 m a.s.l.) in the Atacama Desert. During the late Holocene, riparian ecosystems and farming social groups flourished in the hyperarid Atacama core as surface water availability increased throughout this presently sterile landscape. Twenty-six radiocarbon dates indicate that these events occurred between 1050-680, 1615-1350 and 2500-2040 cal yr BP. Regional comparisons with rodent middens and other records suggest that these events were synchronous with pluvial stages detected at higher-elevations in the central Andes over the last 2500 years. These hydroclimate changes also coincide with periods of pronounced SST gradients in the Tropical Pacific (La Niña-like mode), conditions that are conducive to significantly increased rainfall in the central Andean highlands and flood events in the low-elevation watersheds at inter-annual timescales. Our findings indicate that the positive anomalies in the hyperarid Atacama over the past 2500 years represent a regional response of the central Andean climate system to changes in the global hydrological cycle at centennial timescales. Furthermore, our results provide support for the role of tropical Pacific sea surface temperature gradient changes as the primary mechanism responsible for climate fluctuations in the central Andes. Finally, our results constitute independent evidence for comprehending the

  9. Southwestern Institute of Physics: Annual Report 1998

    International Nuclear Information System (INIS)

    1999-10-01

    The main achievements of controlled nuclear fusion research are presented for Southwestern Institute of Physics in 1998 year. With the establishment and operation of two auxiliary heating systems (NBI, ICRH), the HL-1M Tokamak is equipped with main auxiliary heating and current driving systems such as NBI, ECRH, ICRH and LHCD etc. . In addition, a variety of advanced fueling system, i.e. , multi-shot pellet and supersonic molecular beam injection, the first wall processing technologies of boronization, siliconization and lithiumization as well as more than 20 diagnostic facilities with partial space-time resolution capability have been established on the device. The construction of a larger Tokamak with divertors, the HL-2A, and its complementary systems are being carried out

  10. Genetic diversity of Ascaris in southwestern Uganda

    DEFF Research Database (Denmark)

    Betson, Martha; Nejsum, Peter; Llewellyn-Hughes, Julia

    2012-01-01

    . Microsatellite analysis using eight loci provided evidence for high gene flow between worm populations from the two villages but comparing these worms with others obtained in a prior study on Unguja, Zanzibar, confirmed little genetic exchange and mixing of worm populations between the two areas. By adding......Despite the common occurrence of ascariasis in southwestern Uganda, helminth control in the region has been limited. To gain further insights into the genetic diversity of Ascaris in this area, a parasitological survey in mothers (n=41) and children (n=74) living in two villages, Habutobere...... and Musezero, was carried out. Adult Ascaris worms were collected from infected individuals by chemo-expulsion using pyrantel pamoate treatment. Genetic diversity within these worms was assessed by inspection of DNA sequence variation in a mitochondrial marker and length polymorphism at microsatellite loci...

  11. Environmental Assessment for power marketing policy for Southwestern Power Administration

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-01

    Southwestern Power Administration (Southwestern) needs to renew expiring power sales contracts with new term (10 year) sales contracts. The existing contracts have been in place for several years and many will expire over the next ten years. Southwestern completed an Environmental Assessment on the existing power allocation in June, 1979 (a copy of the EA is attached), and there are no proposed additions of any major new generation resources, service to discrete major new loads, or major changes in operating parameters, beyond those included in the existing power allocation. Impacts from a no action plan, proposed alternative, and market power for less than 10 years are described.

  12. Environmental Assessment for power marketing policy for Southwestern Power Administration

    International Nuclear Information System (INIS)

    1993-01-01

    Southwestern Power Administration (Southwestern) needs to renew expiring power sales contracts with new term (10 year) sales contracts. The existing contracts have been in place for several years and many will expire over the next ten years. Southwestern completed an Environmental Assessment on the existing power allocation in June, 1979 (a copy of the EA is attached), and there are no proposed additions of any major new generation resources, service to discrete major new loads, or major changes in operating parameters, beyond those included in the existing power allocation. Impacts from a no action plan, proposed alternative, and market power for less than 10 years are described

  13. Study on climate change in Southwestern China

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zongxing

    2015-03-01

    Nominated by Chinese Academy of Sciences as an outstanding Ph.D. thesis. Offers a needed exploration of the temporal and spatial pattern of climate change in southwestern China. Explores the action mechanism among the large-scale atmospheric circulation system, the complicated topography, human activities and regional climate changes. Analyzes the response of glaciers to climate change from the aspects of morphology of the glacier, glacial mass balance and the process of hydrology. This thesis confirms many changes, including sharp temperature rise, interannual variability of precipitation, extreme climate events and significant decreases of sunshine duration and wind speed in southwestern China, and systemically explores the action mechanism between large-scale atmospheric circulation systems, the complicated topography, human activities and regional climate changes. This study also analyzes the response of glaciers to climate change so that on the one hand it clearly reflects the relationship between glacier morphologic changes and climate change; on the other, it reveals the mechanism of action of climate warming as a balance between energy and matter. The achievements of this study reflect a significant contribution to the body of research on the response of climate in cold regions, glaciers and human activities to a global change against the background of the typical monsoon climate, and have provided scientific basis for predictions, countermeasures against disasters from extreme weather, utilization of water and the establishment of counterplans to slow and adapt to climate change. Zongxing Li works at the Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, China.

  14. Study on climate change in Southwestern China

    International Nuclear Information System (INIS)

    Li, Zongxing

    2015-01-01

    Nominated by Chinese Academy of Sciences as an outstanding Ph.D. thesis. Offers a needed exploration of the temporal and spatial pattern of climate change in southwestern China. Explores the action mechanism among the large-scale atmospheric circulation system, the complicated topography, human activities and regional climate changes. Analyzes the response of glaciers to climate change from the aspects of morphology of the glacier, glacial mass balance and the process of hydrology. This thesis confirms many changes, including sharp temperature rise, interannual variability of precipitation, extreme climate events and significant decreases of sunshine duration and wind speed in southwestern China, and systemically explores the action mechanism between large-scale atmospheric circulation systems, the complicated topography, human activities and regional climate changes. This study also analyzes the response of glaciers to climate change so that on the one hand it clearly reflects the relationship between glacier morphologic changes and climate change; on the other, it reveals the mechanism of action of climate warming as a balance between energy and matter. The achievements of this study reflect a significant contribution to the body of research on the response of climate in cold regions, glaciers and human activities to a global change against the background of the typical monsoon climate, and have provided scientific basis for predictions, countermeasures against disasters from extreme weather, utilization of water and the establishment of counterplans to slow and adapt to climate change. Zongxing Li works at the Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, China.

  15. Lagrangian particle modeling of air pollution transport in southwestern United States

    Energy Technology Data Exchange (ETDEWEB)

    Uliasz, M. [Warsaw Univ. of Technology (Poland); Stocker, R.A.; Pielke, R.A. [Colorado State Univ., Fort Collins, CO (United States)

    1994-12-31

    Several modeling techniques of various complexity and accuracy are applied in a numerical modeling study of regional air pollution transport being performed within the Measurement Of Haze And Visual Effect (MOHAVE) project. The goal of this study is to assess the impact of the Mohave Power Project (MPP) and other potential sources of air pollution to specific Class I areas located in the desert southwest United States including the Grand Canyon National Park. The Colorado State University team is performing the daily meteorological and dispersion simulations for a year long study using a nonhydrostatic mesoscale meteorological model; the Regional Atmospheric Modeling System (RAMS) coupled with a Lagrangian particle dispersion (LPD) model. The modeling domain covers the southwestern United States with its extremely complex terrain. Two complementary dispersion modeling techniques: a traditional source-oriented approach and receptor-oriented approach are used to calculate concentration and influence function fields, respectively. All computations are performed on two IBM RISC-6000 workstations dedicated to the project. The goal of this paper is to present our design for daily dispersion simulations with an emphasis on influence function calculations using examples from the winter and summer intensive periods of the MOHAVE project.

  16. Factors affecting the thermal environment of Agassiz’s Desert Tortoise (Gopherus agassizii) cover sites in the Central Mojave Desert during periods of temperature extremes

    Science.gov (United States)

    Mack, Jeremy S.; Berry, Kristin H.; Miller, David; Carlson, Andrea S.

    2015-01-01

    Agassiz's Desert Tortoises (Gopherus agassizii) spend >95% of their lives underground in cover sites that serve as thermal buffers from temperatures, which can fluctuate >40°C on a daily and seasonal basis. We monitored temperatures at 30 active tortoise cover sites within the Soda Mountains, San Bernardino County, California, from February 2004 to September 2006. Cover sites varied in type and structural characteristics, including opening height and width, soil cover depth over the opening, aspect, tunnel length, and surficial geology. We focused our analyses on periods of extreme temperature: in summer, between July 1 and September 1, and winter, between November 1 and February 15. With the use of multivariate regression tree analyses, we found cover-site temperatures were influenced largely by tunnel length and subsequently opening width and soil cover. Linear regression models further showed that increasing tunnel length increased temperature stability and dampened seasonal temperature extremes. Climate change models predict increased warming for southwestern North America. Cover sites that buffer temperature extremes and fluctuations will become increasingly important for survival of tortoises. In planning future translocation projects and conservation efforts, decision makers should consider habitats with terrain and underlying substrate that sustain cover sites with long tunnels and expanded openings for tortoises living under temperature extremes similar to those described here or as projected in the future.

  17. Paleoclimate Signals and Temperature Reconstructions for the Northeastern United States using Atlantic White Cedar Tree-Rings

    Science.gov (United States)

    Pearl, J. K.; Anchukaitis, K. J.; Pederson, N.; Donnelly, J. P.

    2016-12-01

    High-resolution paleoclimate records of the Common Era are essential for improving detection and attribution of internal and forced climate system responses. The densely populated northeastern United States is at risk from impending climate shifts as well as sea level rise. Here we present a new network of annually resolved proxy data from Atlantic white cedar trees throughout the northeastern United States. Ring width variability reflects winter through summer temperatures at inland sites north of New Jersey. Climate signals embedded in the full network are evaluated for their potential to provide reconstructions of both temperature and drought variability. We demonstrate skillful climate reconstructions for the last several centuries and the potential to use subfossil samples to extend these records over the Common Era. Our tree-ring network provides the long-term context at multidecadal and centennial time scales for the large-scale ocean-atmospheric processes that influence the climate of the region.

  18. Desert wetlands in the geologic record

    Science.gov (United States)

    Pigati, Jeff S.; Rech, Jason A.; Quade, Jay; Bright, Jordon; Edwards, L.; Springer, A.

    2014-01-01

    Desert wetlands support flora and fauna in a variety of hydrologic settings, including seeps, springs, marshes, wet meadows, ponds, and spring pools. Over time, eolian, alluvial, and fluvial sediments become trapped in these settings by a combination of wet ground conditions and dense plant cover. The result is a unique combination of clastic sediments, chemical precipitates, and organic matter that is preserved in the geologic record as ground-water discharge (GWD) deposits. GWD deposits contain information on the timing and magnitude of past changes in water-table levels and, therefore, are a potential source of paleohydrologic and paleoclimatic information. In addition, they can be important archeological and paleontological archives because desert wetlands provide reliable sources of fresh water, and thus act as focal points for human and faunal activities, in some of the world's harshest and driest lands. Here, we review some of the physical, sedimentological, and geochemical characteristics common to GWD deposits, and provide a contextual framework that researchers can use to identify and interpret geologic deposits associated with desert wetlands. We discuss several lines of evidence used to differentiate GWD deposits from lake deposits (they are commonly confused), and examine how various types of microbiota and depositional facies aid in reconstructing past environmental and hydrologic conditions. We also review how late Quaternary GWD deposits are dated, as well as methods used to investigate desert wetlands deeper in geologic time. We end by evaluating the strengths and limitations of hydrologic and climatic records derived from GWD deposits, and suggest several avenues of potential future research to further develop and utilize these unique and complex systems.

  19. Biology of the Central Desert of Oman

    OpenAIRE

    GHAZANFAR, Shahina A

    2004-01-01

    A biological survey of the central desert of Oman was done using long distance transects. Vegetation was sparse and consisted of 200+ plant species, 22 species of mammals, 17 species of reptiles and amphibians, and more than 50 species of birds (migratory and resident). Three main vegetation types were identified based on ground substrate and the dominance of species. These were communities with Acacia Willd., Zygophyllum L., and open woodlands of Prosopis cineraria (L.) Druce. Over-grazing a...

  20. Joint by Design: The Western Desert Campaign

    Science.gov (United States)

    2015-05-21

    Introduction Seated in a dusty tent, finally cooling in the Egyptian night, the “Desert Fox” had a serious problem. German Lieutenant General Erwin...Complexity: A Platform for Designing Business Architecture , 2nd ed. (Amsterdam: Elsevier, 2006), 30-32. 65 Lewin, Montgomery, 121. 29 Allies...Benghazi and Tobruk, and the Egyptian port of Matruh were operating at 60 percent of their potential capacity. By the end of August, the Axis loss rate of

  1. Extrafloral nectar fuels ant life in deserts

    OpenAIRE

    Aranda-Rickert, Adriana; Diez, Patricia; Marazzi, Brigitte

    2014-01-01

    Interactions mediated by extrafloral nectary (EFN)-bearing plants that reward ants with a sweet liquid secretion are well documented in temperate and tropical habitats. However, their distribution and abundance in deserts are poorly known. In this study, we test the predictions that biotic interactions between EFN plants and ants are abundant and common also in arid communities and that EFNs are only functional when new vegetative and reproductive structures are developing. In a seasonal dese...

  2. Liquid Water Restricts Habitability in Extreme Deserts

    Science.gov (United States)

    Cockell, Charles S.; Brown, Sarah; Landenmark, Hanna; Samuels, Toby; Siddall, Rebecca; Wadsworth, Jennifer

    2017-04-01

    Liquid water is a requirement for biochemistry, yet under some circumstances it is deleterious to life. Here, we show that liquid water reduces the upper temperature survival limit for two extremophilic photosynthetic microorganisms (Gloeocapsa and Chroococcidiopsis spp.) by greater than 40°C under hydrated conditions compared to desiccated conditions. Under hydrated conditions, thermal stress causes protein inactivation as shown by the fluorescein diacetate assay. The presence of water was also found to enhance the deleterious effects of freeze-thaw in Chroococcidiopsis sp. In the presence of water, short-wavelength UV radiation more effectively kills Gloeocapsa sp. colonies, which we hypothesize is caused by factors including the greater penetration of UV radiation into hydrated colonies compared to desiccated colonies. The data predict that deserts where maximum thermal stress or irradiation occurs in conjunction with the presence of liquid water may be less habitable to some organisms than more extreme arid deserts where organisms can dehydrate prior to being exposed to these extremes, thus minimizing thermal and radiation damage. Life in extreme deserts is poised between the deleterious effects of the presence and the lack of liquid water.

  3. The Palm Desert renewable [hydrogen] transportation system

    Energy Technology Data Exchange (ETDEWEB)

    Chamberlin, C.E.; Lehman, P. [Humboldt State Univ., Arcata, CA (United States). Schatz Energy Research Center

    1998-08-01

    This paper describes the Schatz Energy Research Center (SERC) progress on the Palm Desert Renewable Hydrogen Transportation System Project for the period June 1997 through May 1998. The project began in March 1996. The goal of the Palm Desert Project is to develop a clean and sustainable transportation system for a community. The project demonstrates the practical utility of hydrogen as a transportation fuel and the proton exchange membrane (PEM) fuel cell as a vehicle power system. The project includes designing and building 4 fuel cell powered vehicles, a solar hydrogen generating and refueling station, and a fuel cell vehicle diagnostic center. Over this last year, SERC has built a fuel cell powered neighborhood electric vehicle and delivered it to the City of Palm Desert. The design of the hydrogen refueling station is near completion and it is anticipated that construction will be complete in the fall of 1998. The vehicles are currently being refueled at a temporary refueling station. The diagnostic center is being designed and maintenance procedures as well as computer diagnostic programs for the fuel cell vehicles are being developed. City employees are driving the vehicles daily and monitoring data are being collected. The drivers are pleased with the performance of the vehicles.

  4. ON PHYTOCOENOTICAL MAPPING OF CASPIAN DESERT REGION

    Directory of Open Access Journals (Sweden)

    I. SAFRONOVA

    2004-05-01

    Full Text Available The phytoecological map (l :2.500.000 for Desert Region, including the Caspian Lowland and the Mangyshlak. has been compiled. It gives an idea of latitudinal differentiation cf vegetation. Edaphic variants and lithological composition in low mountains. The legend has been constructed according to zonal-typological principle e using an ecological-phytocoenotic classification. Heterogeneity of vegetation is reflected by means of territoria1 units (complex, series, combination and additional marks above the vegetation background. In the northern subzone vegetation is fairly monotonous and characterized by prevalence of wormwood communities (Artemisia of subgenus Seriphidium, joined in three formations: Artemisia lerchiana, A. arenaria. A. pauciflora. Small areas are occupied by shrub deserts of Calligollum aphyllum and Tamarix ramosissima. To southward of 47° N in the middle subzone on the Caspian Lowland the communities of halophyte perennial saltworts essential1y dominate, and to less extent-wormwood communities of hemipsammophytic Artemisia terrae-albae and psammophytic Artemisia arenaria and A. lerchiana. Deserts of Mangyshlak are much diverse. Dwarf semishrubs are presented by species of perennial saltworts (Anabasis salsa, Nanophyton erinaceum,Arthrophytum lehnwnianum, Salsola orientaUs and wonnwood (Artemisia terrae-albae, A. gurganica. A. santolina. To southward of 43° N in the southern subzone dwarf semishrub Salsola gemmascens and Artemisia kemrudica corrnnunities prevail.

  5. ON PHYTOCOENOTICAL MAPPING OF CASPIAN DESERT REGION

    Directory of Open Access Journals (Sweden)

    I. SAFRONOVA

    2004-01-01

    Full Text Available The phytoecological map (l :2.500.000 for Desert Region, including the Caspian Lowland and the Mangyshlak. has been compiled. It gives an idea of latitudinal differentiation cf vegetation. Edaphic variants and lithological composition in low mountains. The legend has been constructed according to zonal-typological principle e using an ecological-phytocoenotic classification. Heterogeneity of vegetation is reflected by means of territoria1 units (complex, series, combination and additional marks above the vegetation background. In the northern subzone vegetation is fairly monotonous and characterized by prevalence of wormwood communities (Artemisia of subgenus Seriphidium, joined in three formations: Artemisia lerchiana, A. arenaria. A. pauciflora. Small areas are occupied by shrub deserts of Calligollum aphyllum and Tamarix ramosissima. To southward of 47° N in the middle subzone on the Caspian Lowland the communities of halophyte perennial saltworts essential1y dominate, and to less extent-wormwood communities of hemipsammophytic Artemisia terrae-albae and psammophytic Artemisia arenaria and A. lerchiana. Deserts of Mangyshlak are much diverse. Dwarf semishrubs are presented by species of perennial saltworts (Anabasis salsa, Nanophyton erinaceum,Arthrophytum lehnwnianum, Salsola orientaUs and wonnwood (Artemisia terrae-albae, A. gurganica. A. santolina. To southward of 43° N in the southern subzone dwarf semishrub Salsola gemmascens and Artemisia kemrudica corrnnunities prevail.

  6. CAMEL REARING IN CHOLISTAN DESERT OF PAKISTAN

    Directory of Open Access Journals (Sweden)

    I. ALI, M. SHAFIQ CHAUDHRY1 AND U. FAROOQ

    2009-05-01

    Full Text Available The camel is one of the typical and the best adopted animals of the desert, capable of enduring thirst and hunger for days and is the most patient of land animals. For desert nomads of Pakistani Cholistan, it is a beloved companion, a source of milk and meat, transport facility provider and a racing/dancing animal, thus, playing an important role in the socioeconomic uplift of the local community. Camels of Marrecha or Mahra breed are mainly used for riding and load carrying but may be trained for dancing or racing. Berella is another heavy and milch breed of camel famous for milk production and can produce upto 10-15 liters of milk per day. This breed is also suitable for draught purpose, though comparatively slow due to heavy body. The present paper also describes the traditional camel rearing system used by nomads of Cholistan desert. Some aspects of camel health, production, feeding, socio-economic values, marketing and some constraints and suggestions are also given so that the policy makers may consider them for the welfare of this animal.

  7. 77 FR 65133 - Revisions to the California State Implementation Plan, Mojave Desert Air Quality Management District

    Science.gov (United States)

    2012-10-25

    ... the California State Implementation Plan, Mojave Desert Air Quality Management District AGENCY... limited disapproval of revisions to the Mojave Desert Air Quality Management District (MDAQMD) portion of.... * * * * * (c) * * * (379) * * * (i) * * * (E) Mojave Desert Air Quality Management District. (1) Rule 1159...

  8. Nationwide desert highway assessment: a case study in China.

    Science.gov (United States)

    Mao, Xuesong; Wang, Fuchun; Wang, Binggang

    2011-07-01

    The natural environment affects the construction of desert highways. Conversely, highway construction affects the natural environment and puts the ecological environment at a disadvantage. To satisfy the variety and hierarchy of desert highway construction and discover the spatio-temporal distribution of the natural environment and its effect on highway construction engineering, an assessment of the natural regional divisions of desert highways in China is carried out for the first time. Based on the general principles and method for the natural region division, the principles, method and index system for desert highway assessment is put forward by combining the desert highway construction features and the azonal differentiation law. The index system combines the dominant indicator and four auxiliary indicators. The dominant indicator is defined by the desert's comprehensive state index and the auxiliary indicators include the sand dune height, the blown sand strength, the vegetation coverage ratio and the annual average temperature difference. First the region is divided according to the dominant indicator. Then the region boundaries are amended according to the four auxiliary indicators. Finally the natural region division map for desert highway assessment is presented. The Chinese desert highways can be divided into three sections: the east medium effect region, the middle medium-severe effect region, and the west slight-medium effect region. The natural region division map effectively paves the way for the route planning, design, construction, maintenance and ongoing management of desert highways, and further helps environmental protection.

  9. The provenance of Taklamakan desert sand

    Science.gov (United States)

    Rittner, Martin; Vermeesch, Pieter; Carter, Andrew; Bird, Anna; Stevens, Thomas; Garzanti, Eduardo; Andò, Sergio; Vezzoli, Giovanni; Dutt, Ripul; Xu, Zhiwei; Lu, Huayu

    2016-03-01

    Sand migration in the vast Taklamakan desert within the Tarim Basin (Xinjiang Uyghur Autonomous region, PR China) is governed by two competing transport agents: wind and water, which work in diametrically opposed directions. Net aeolian transport is from northeast to south, while fluvial transport occurs from the south to the north and then west to east at the northern rim, due to a gradual northward slope of the underlying topography. We here present the first comprehensive provenance study of Taklamakan desert sand with the aim to characterise the interplay of these two transport mechanisms and their roles in the formation of the sand sea, and to consider the potential of the Tarim Basin as a contributing source to the Chinese Loess Plateau (CLP). Our dataset comprises 39 aeolian and fluvial samples, which were characterised by detrital-zircon U-Pb geochronology, heavy-mineral, and bulk-petrography analyses. Although the inter-sample differences of all three datasets are subtle, a multivariate statistical analysis using multidimensional scaling (MDS) clearly shows that Tarim desert sand is most similar in composition to rivers draining the Kunlun Shan (south) and the Pamirs (west), and is distinctly different from sediment sources in the Tian Shan (north). A small set of samples from the Junggar Basin (north of the Tian Shan) yields different detrital compositions and age spectra than anywhere in the Tarim Basin, indicating that aeolian sediment exchange between the two basins is minimal. Although river transport dominates delivery of sand into the Tarim Basin, wind remobilises and reworks the sediment in the central sand sea. Characteristic signatures of main rivers can be traced from entrance into the basin to the terminus of the Tarim River, and those crossing the desert from the south to north can seasonally bypass sediment through the sand sea. Smaller ephemeral rivers from the Kunlun Shan end in the desert and discharge their sediment there. Both river run

  10. The Use of Water During the Crew 144, Mars Desert Research Station, Utah Desert

    Science.gov (United States)

    De Morais Mendonca Teles, Antonio

    2016-07-01

    Well. from November 29th to December 14th, 2014, the author conducted astrobiological and geological surveys, as analog astronaut member of the international Crew 144, at the site of the Mars Society's Mars Desert Research Station, located at a remote location in the Utah desert, United States. The use of water for drinking, bathing, cleaning, etc., in the crew was a major issue for consideration for a human expedition to the planet Mars in the future. The author would like to tell about the factors of the rationalized use of water.

  11. Cost estimates for Operation Desert Shield/Desert Storm: a budgetary analysis

    OpenAIRE

    Johnson, J. Andrew.

    1991-01-01

    Operation Desert Shield/Desert Storm (DS/DS) presented unique challenges for estimating the cost of that conflict. This analysis reviews the cost estimates and methodologies developed for that purpose by DoD, CBO and GAO. It considers the budget climate and the role of foreign cash and in-kind contributions. Finally, it reviews the budgeting innovations used to provide and monitor DS/DS defense spending. At the outset of the crisis, costs were estimated to determine the defense funding requir...

  12. Faulting and groundwater in a desert environment: constraining hydrogeology using time-domain electromagnetic data

    Science.gov (United States)

    Bedrosian, Paul A.; Burgess, Matthew K.; Nishikawa, Tracy

    2013-01-01

    Within the south-western Mojave Desert, the Joshua Basin Water District is considering applying imported water into infiltration ponds in the Joshua Tree groundwater sub-basin in an attempt to artificially recharge the underlying aquifer. Scarce subsurface hydrogeological data are available near the proposed recharge site; therefore, time-domain electromagnetic (TDEM) data were collected and analysed to characterize the subsurface. TDEM soundings were acquired to estimate the depth to water on either side of the Pinto Mountain Fault, a major east-west trending strike-slip fault that transects the proposed recharge site. While TDEM is a standard technique for groundwater investigations, special care must be taken when acquiring and interpreting TDEM data in a twodimensional (2D) faulted environment. A subset of the TDEM data consistent with a layered-earth interpretation was identified through a combination of three-dimensional (3D) forward modelling and diffusion time-distance estimates. Inverse modelling indicates an offset in water table elevation of nearly 40 m across the fault. These findings imply that the fault acts as a low-permeability barrier to groundwater flow in the vicinity of the proposed recharge site. Existing production wells on the south side of the fault, together with a thick unsaturated zone and permeable near-surface deposits, suggest the southern half of the study area is suitable for artificial recharge. These results illustrate the effectiveness of targeted TDEM in support of hydrological studies in a heavily faulted desert environment where data are scarce and the cost of obtaining these data by conventional drilling techniques is prohibitive.

  13. Holocene temperature variability revealed by brGDGTs in subtropical southwestern China

    Science.gov (United States)

    Feng, X.; Zhao, C.

    2017-12-01

    Subtropical areas are important source region of moisture and heat in global climate system. Paleoclimate reconstructions from these regions, especially quantitative records, would not only help to better understand the nature of climate system through time, but also provide important constraining dataset for long-term ecosystem variations in these ecological important areas. To date, quantitative climate records with reliable chronological controls are still limited from terrestrial archives in subtropical areas. Here we present a 50-year-resolution quantitative temperature record throughout the Holocene based on branched GDGTs at a small alpine lake, Tiancai Lake (26°38'E, 99°43'N, 3898 m.a.s.l) in southwestern China. The record is based on a temporal calibration between instrumental mean annual air temperature (MAAT) and brGDGT compounds (GDGT-IIIa, GDGT-IIa', GDGT-IIb, GDGT-Ia and GDGT-Ic). The MAAT was relatively low -0.6 ° between 11 and 7.5 ka, then abruptly increased 1 ° to 4 °until 7 ka. The MAAT was relatively warm 2° between 7 and 1 ka, then decreased to 1° over the last 1 ka. The Middle to Late Holocene was 3 ° warmer than the Early Holocene. The MAAT variation at Lake Tiancai is supported by changes in evergreen oaks and Tsuga from the same sediment core, suggesting that the growth of cold-tolerant forest in place of subtropical evergreen broadleaved forest has been driven by the decrease in MAAT. The early Holocene cold interval revealed by our record and pollen data is different with the chironomid-based summer temperature reconstruction from the same lake, the latter has been driven by summer insolation. This difference suggests that a pronounced winter contribution to the mean annual temperature during the early Holocene, which was probably caused by a low winter insolation, and strengthened by a sparse vegetation cover and influences of winter ice/snow cover in tropical high latitude regions.

  14. On the edge of Bantu expansions: mtDNA, Y chromosome and lactase persistence genetic variation in southwestern Angola

    Directory of Open Access Journals (Sweden)

    Beleza Sandra

    2009-04-01

    Full Text Available Abstract Background Current information about the expansion of Bantu-speaking peoples is hampered by the scarcity of genetic data from well identified populations from southern Africa. Here, we fill an important gap in the analysis of the western edge of the Bantu migrations by studying for the first time the patterns of Y-chromosome, mtDNA and lactase persistence genetic variation in four representative groups living around the Namib Desert in southwestern Angola (Ovimbundu, Ganguela, Nyaneka-Nkumbi and Kuvale. We assessed the differentiation between these populations and their levels of admixture with Khoe-San groups, and examined their relationship with other sub-Saharan populations. We further combined our dataset with previously published data on Y-chromosome and mtDNA variation to explore a general isolation with migration model and infer the demographic parameters underlying current genetic diversity in Bantu populations. Results Correspondence analysis, lineage sharing patterns and admixture estimates indicate that the gene pool from southwestern Angola is predominantly derived from West-Central Africa. The pastoralist Herero-speaking Kuvale people were additionally characterized by relatively high frequencies of Y-chromosome (12% and mtDNA (22% Khoe-San lineages, as well as by the presence of the -14010C lactase persistence mutation (6%, which likely originated in non-Bantu pastoralists from East Africa. Inferred demographic parameters show that both male and female populations underwent significant size growth after the split between the western and eastern branches of Bantu expansions occurring 4000 years ago. However, males had lower population sizes and migration rates than females throughout the Bantu dispersals. Conclusion Genetic variation in southwestern Angola essentially results from the encounter of an offshoot of West-Central Africa with autochthonous Khoisan-speaking peoples from the south. Interactions between the Bantus

  15. Are Wildlife Detector Dogs or People Better at Finding Desert Tortoises (Gopherus Agassizii)?

    National Research Council Canada - National Science Library

    Nussear, Kenneth E; Esque, Todd C; Heaton, Jill S; Cablk, Mary E; Drake, Kristina K; Valentin, Cindee; Yee, Julie L; Medica, Philip A

    2008-01-01

    .... Recent studies highlight the effectiveness of trained detector dogs to locate wildlife during field surveys, including Desert Tortoises in a semi-natural setting. Desert Tortoises (Gopherus agassizii...

  16. Cambrian trilobites with Siberian affinities, southwestern Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, A.R.; Egbert, R.M.; Sullivan, R.; Knoth, J.S.

    1985-02-01

    Cambrian trilobites occur in two levels (about 7 m apart) in the core of a large, complex anticlinal structure in the area between the Taylor Mountains and the Hoholitna River in southwestern Alaska. The lower collection contains Erbia, Macannaia (a species close to Soviet forms described as Pagetia ferox Lermontova), two species of Kootenia (including one perhaps cospecific with forms from the central Brooks range), and several species of ptychoparioid trilobites. It is clear that biogeographic affinities are with the transitional facies of the eastern Siberian platform and the south Siberian foldbelt. In Soviet terms, the age of the collection falls in a disputed interval called latest Early Cambrian (Tojonian) by some authors, and earliest Middle Cambrian (Amgan) by others. In North American terms, Macannaia is known only from early Middle Cambrian beds. The younger collection contains abundant agnostids, a variety of conocoryphids, Paradoxides, and several species of ptychoparioid trilobites. This is an assemblage of undoubted late Middle Cambrian age, comparable to faunas described from the Maya State of the Siberian platform and the Paradoxides paradoxissimus Stage of the Baltic region. Both faunas are from ocean-facing or outer shelf environments. None of the key non-agnostid or non-pagetiid elements have been seen previously in deposits of Cambrian North America.

  17. Reconstruction of early Holocene paleoclimate and environment in the SW Kola region, Russian Arctic

    Science.gov (United States)

    Grekov, Ivan; Kolka, Vasiliy; Syrykh, Liudmila; Nazarova, Larisa

    2016-04-01

    , et al., 2013). Reconstruction of the Early Holocene average July air temperatures based on chironomid analysis showed that in the middle of the Peninsula air T July were around + 10.3oC which is below the modern values. A sharp warming took place then during the Mid Holocene optimum (Ilyashuk, 2000; Ilyashuk, 2013). The reconstructed Early Holocene T July of the southern part of the Peninsula are similar to the modern T July + 12oC. For a detailed reconstruction of paleogeographic environments of the south-western part of the Kola Peninsula in Holocene we studied the valley of Kolvica river and the southern shore of lake Kolvitsa (67.01-67.11 N; 33.17-33.48 E). Analysis of lithological sequences and radiocarbon dating of sediments of small lakes present a clear outline of the development of the studied region from 9.3 14C ka (10.5 cal. ka BP) to the present day. Based on micro-paleontological analyzes we performed a qualitative reconstruction of climatic conditions during the Holocene, which shows a clear change of cooling and warming in the studied area, as well as the dynamics of the White Sea coastal zone and the development of the studied lake basins. This project was financed by RFBR 15-35-50479 mol_nr.

  18. Spreaders, igniters, and burning shrubs: plant flammability explains novel fire dynamics in grass-invaded deserts.

    Science.gov (United States)

    Fuentes-Ramirez, Andres; Veldman, Joseph W; Holzapfel, Claus; Moloney, Kirk A

    2016-10-01

    Novel fire regimes are an important cause and consequence of global environmental change that involve interactions among biotic, climatic, and human components of ecosystems. Plant flammability is key to these interactions, yet few studies directly measure flammability or consider how multiple species with different flammabilities interact to produce novel fire regimes. Deserts of the southwestern United States are an ideal system for exploring how novel fire regimes can emerge when fire-promoting species invade ecosystems comprised of species that did not evolve with fire. In these deserts, exotic annual grasses provide fuel continuity across landscapes that did not historically burn. These fires often ignite a keystone desert shrub, the fire-intolerant creosote bush, Larrea tridentata (DC.) Coville. Ignition of Larrea is likely catalyzed by fuels produced by native plants that grow beneath the shrubs. We hypothesize that invasive and native species exhibit distinct flammability characteristics that in combination determine spatial patterns of fire spread and intensity. We measured flammability metrics of Larrea, two invasive grasses, Schismus arabicus and Bromus madritensis, and two native plants, the sub-shrub Ambrosia dumosa and the annual herb Amsinckia menziesii. Results of laboratory experiments show that the grasses carry fire quickly (1.32 cm/s), but burn for short duration (0.5 min) at low temperatures. In contrast, native plants spread fire slowly (0.12 cm/s), but burn up to eight times longer (4 min) and produced hotter fires. Additional experiments on the ignition requirements of Larrea suggest that native plants burn with sufficient temperature and duration to ignite dead Larrea branches (time to ignition, 2 min; temperature at ignition 692°C). Once burning, these dead branches ignite living branches in the upper portions of the shrub. Our study provides support for a conceptual model in which exotic grasses are "spreaders" of fire and native

  19. Physiological conjunction of allelochemicals and desert plants.

    Science.gov (United States)

    Yosef Friedjung, Avital; Choudhary, Sikander Pal; Dudai, Nativ; Rachmilevitch, Shimon

    2013-01-01

    Plants exchange signals with other physical and biological entities in their habitat, a form of communication termed allelopathy. The underlying principles of allelopathy and secondary-metabolite production are still poorly understood, especially in desert plants. The coordination and role of secondary metabolites were examined as a cause of allelopathy in plants thriving under arid and semiarid soil conditions. Desert plant species, Origanum dayi, Artemisia sieberi and Artemisia judaica from two different sources (cultivar cuttings and wild seeds) were studied in their natural habitats. Growth rate, relative water content, osmotic potential, photochemical efficiency, volatile composition and vital factors of allelopathy were analyzed at regular intervals along four seasons with winter showing optimum soil water content and summer showing water deficit conditions. A comprehensive analysis of the volatile composition of the leaves, ambient air and soil in the biological niche of the plants under study was carried out to determine the effects of soil water conditions and sample plants on the surrounding flora. Significant morpho-physiological changes were observed across the seasons and along different soil water content. Metabolic analysis showed that water deficit was the key for driving selective metabolomic shifts. A. judaica showed the least metabolic shifts, while A. sieberi showed the highest shifts. All the species exhibited high allelopathic effects; A. judaica displayed relatively higher growth-inhibition effects, while O. dayi showed comparatively higher germination-inhibition effects in germination assays. The current study may help in understanding plant behavior, mechanisms underlying secondary-metabolite production in water deficit conditions and metabolite-physiological interrelationship with allelopathy in desert plants, and can help cull economic benefits from the produced volatiles.

  20. Physiological conjunction of allelochemicals and desert plants.

    Directory of Open Access Journals (Sweden)

    Avital Yosef Friedjung

    Full Text Available Plants exchange signals with other physical and biological entities in their habitat, a form of communication termed allelopathy. The underlying principles of allelopathy and secondary-metabolite production are still poorly understood, especially in desert plants. The coordination and role of secondary metabolites were examined as a cause of allelopathy in plants thriving under arid and semiarid soil conditions. Desert plant species, Origanum dayi, Artemisia sieberi and Artemisia judaica from two different sources (cultivar cuttings and wild seeds were studied in their natural habitats. Growth rate, relative water content, osmotic potential, photochemical efficiency, volatile composition and vital factors of allelopathy were analyzed at regular intervals along four seasons with winter showing optimum soil water content and summer showing water deficit conditions. A comprehensive analysis of the volatile composition of the leaves, ambient air and soil in the biological niche of the plants under study was carried out to determine the effects of soil water conditions and sample plants on the surrounding flora. Significant morpho-physiological changes were observed across the seasons and along different soil water content. Metabolic analysis showed that water deficit was the key for driving selective metabolomic shifts. A. judaica showed the least metabolic shifts, while A. sieberi showed the highest shifts. All the species exhibited high allelopathic effects; A. judaica displayed relatively higher growth-inhibition effects, while O. dayi showed comparatively higher germination-inhibition effects in germination assays. The current study may help in understanding plant behavior, mechanisms underlying secondary-metabolite production in water deficit conditions and metabolite-physiological interrelationship with allelopathy in desert plants, and can help cull economic benefits from the produced volatiles.

  1. Birds and conservation significance of the Namib Desert's least ...

    African Journals Online (AJOL)

    -long Namib Desert and it remains the least known coastal wetland on a desert coast rich in shorebirds. Two surveys of the Baia dos Tigres region in 1999 and 2001 indicated a rich wetland bird diversity consisting of 25 species, with a total of ...

  2. Screening the Egyptian desert actinomycetes as candidates for new ...

    African Journals Online (AJOL)

    In a screening program to study the antimicrobial activities of desert actinomycetes as potential producers of active metabolites, 75 actinomycete strains were isolated from the Egyptian desert habitats and tested. Out of the isolated 75 organisms, 32 (42.67%) showed activity against the used test organisms.

  3. Pastoralist rock art in the Black Desert of Jordan

    NARCIS (Netherlands)

    Brusgaard, N.O.

    2015-01-01

    This paper discusses the current problems that exist with the rock art research of the Black Desert in Jordan and presents some preliminary field results of the author’s research on the petroglyphs. It also explore the possibilities that the rock art affords to learn more about the elusive desert

  4. Pastoralist rock art in the Black Desert of Jordan

    OpenAIRE

    Brusgaard, N.O.

    2015-01-01

    This paper discusses the current problems that exist with the rock art research of the Black Desert in Jordan and presents some preliminary field results of the author’s research on the petroglyphs. It also explore the possibilities that the rock art affords to learn more about the elusive desert societies and the limitations about studying rock art in archaeologically unfamiliar territories.

  5. The politics of accessing desert land in Jordan

    NARCIS (Netherlands)

    Naber, Al Majd; Molle, Francois

    2016-01-01

    With the dramatic increase of the population in Jordan, the value of land has rocketed up. Urban sprawl into semi-desert or desert areas, initially not surveyed or settled by the British and considered as state land, has brought to the surface the problematic status of those lands. Likewise, the

  6. Aeromycobiota of Western Desert of Egypt | Ismail | African Journal ...

    African Journals Online (AJOL)

    The prevalence of airborne mycobiota at six different regions of Western desert (5 regions) and Eastern desert (1) of Egypt was determined using the exposed-plate method. A total of 44 genera, 102 species and one variety in addition to some unidentified yeasts and dark sterile mycelia were collected. Of the above, only 5 ...

  7. The Desert and the Sown Project in Northern Jordan

    DEFF Research Database (Denmark)

    Kerner, Susanne

    2014-01-01

    The desert and sown project, which started in 1999 and continued in 2008-2009, studied the region between the settled areas east of Irbid and Ramtha and the surrounding desert at Mafraq (northern Jordan). Large parts of the material comes from the Palaeolithic period, while some smaller tells date...

  8. Desert tortoise use of burned habitat in the Eastern Mojave desert

    Science.gov (United States)

    Drake, Karla K.; Esque, Todd C.; Nussear, Kenneth E.; DeFalco, Lesley; Scoles, Sara; Modlin, Andrew T.; Medica, Philip A.

    2015-01-01

    Wildfires burned 24,254 ha of critical habitat designated for the recovery of the threatened Mojave desert tortoise (Gopherus agassizii) in southern Nevada during 2005. The proliferation of non-native annual grasses has increased wildfire frequency and extent in recent decades and continues to accelerate the conversion of tortoise habitat across the Mojave Desert. Immediate changes to vegetation are expected to reduce quality of critical habitat, yet whether tortoises will use burned and recovering habitat differently from intact unburned habitat is unknown. We compared movement patterns, home-range size, behavior, microhabitat use, reproduction, and survival for adult desert tortoises located in, and adjacent to, burned habitat to understand how tortoises respond to recovering burned habitat. Approximately 45% of home ranges in the post-fire environment contained burned habitat, and numerous observations (n = 12,223) corroborated tortoise use of both habitat types (52% unburned, 48% burned). Tortoises moved progressively deeper into burned habitat during the first 5 years following the fire, frequently foraging in burned habitats that had abundant annual plants, and returning to adjacent unburned habitat for cover provided by intact perennial vegetation. However, by years 6 and 7, the live cover of the short-lived herbaceous perennial desert globemallow (Sphaeralcea ambigua) that typically re-colonizes burned areas declined, resulting in a contraction of tortoise movements from the burned areas. Health and egg production were similar between burned and unburned areas indicating that tortoises were able to acquire necessary resources using both areas. This study documents that adult Mojave desert tortoises continue to use habitat burned once by wildfire. Thus, continued management of this burned habitat may contribute toward the recovery of the species in the face of many sources of habitat loss.

  9. Climate regime shifts in paleoclimate time series from the Yucatán Peninsula: from the Preclassic to Classic period

    Science.gov (United States)

    Polanco Martínez, Josue M.; Medina-Elizalde, Martin; Burns, Stephen J.; Jiang, Xiuyang; Shen, Chuan-Chou

    2015-04-01

    It has been widely accepted by the paleoclimate and archaeology communities that extreme climate events (especially droughts) and past climate change played an important role in the cultural changes that occurred in at least some parts of the Maya Lowlands, from the Pre-Classic (2000 BC to 250 AD) to Post-Classic periods (1000 to 1521 AD) [1, 2]. In particular, a large number of studies suggest that the decline of the Maya civilization in the Terminal Classic Period was greatly influenced by prolonged severe drought events that probably triggered significant societal disruptions [1, 3, 4, 5]. Going further on these issues, the aim of this work is to detect climate regime shifts in several paleoclimate time series from the Yucatán Peninsula (México) that have been used as rainfall proxies [3, 5, 6, 7]. In order to extract information from the paleoclimate data studied, we have used a change point method [8] as implemented in the R package strucchange, as well as the RAMFIT method [9]. The preliminary results show for all the records analysed a prominent regime shift between 400 to 200 BCE (from a noticeable increase to a remarkable fall in precipitation), which is strongest in the recently obtained stalagmite (Itzamna) delta18-O precipitation record [7]. References [1] Gunn, J. D., Matheny, R. T., Folan, W. J., 2002. Climate-change studies in the Maya area. Ancient Mesoamerica, 13(01), 79-84. [2] Yaeger, J., Hodell, D. A., 2008. The collapse of Maya civilization: assessing the interaction of culture, climate, and environment. El Niño, Catastrophism, and Culture Change in Ancient America, 197-251. [3] Hodell, D. A., Curtis, J. H., Brenner, M., 1995. Possible role of climate in the collapse of Classic Maya civilization. Nature, 375(6530), 391-394. [4] Aimers, J., Hodell, D., 2011. Societal collapse: Drought and the Maya. Nature 479(7371), 44-45 (2011). [5] Medina-Elizalde, M., Rohling, E. J., 2012. Collapse of Classic Maya civilization related to modest reduction

  10. Algae-production in the desert

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrand, H.

    1988-11-01

    The company Koor Food Ltd. (Israel) developed in co-operation with the Weizmann-Institute (Israel) a production-plant for the industrial cultivation of algae in the desert area of Elat. For almost a year now, they succeed in harvesting large amounts of algae material with the help of the intensive sun and the Red Sea water. The alga Dunaliella with the natural US -carotine, as well as the alga Spirulina with the high content of protein find their market in the food-, cosmetic- and pharma-industry. This article will give a survey of a yet here unusual project.

  11. Background aerosol composition in the Namib desert

    International Nuclear Information System (INIS)

    Annegarn, H.J.; Sellschop, J.P.F.; Van Grieken, R.E.; Winchester, J.W.

    The sulfur content of atmospheric particulate matter in non-urban areas is apparently rising above natural levels in the Northern Hemisphere. Sulfur emissions to the atmosphere are also increasing with increasing combustion of fossil fuels. Current research is being focussed not only on gaseous sulfur dioxide, but also on particulate forms, including sulfates and sulfuric acid. A global network of non urban studies using proton induced X-ray emission (PIXE) of which the sampling site at Gobabeb in the Namib desert is one, are developing a data base on which questions of natural levels of sulfur can be answered

  12. Tectonics, orbital forcing, global climate change, and human evolution in Africa: introduction to the African paleoclimate special volume.

    Science.gov (United States)

    Maslin, Mark A; Christensen, Beth

    2007-11-01

    The late Cenozoic climate of Africa is a critical component for understanding human evolution. African climate is controlled by major tectonic changes, global climate transitions, and local variations in orbital forcing. We introduce the special African Paleoclimate Issue of the Journal of Human Evolution by providing a background for and synthesis of the latest work relating to the environmental context for human evolution. Records presented in this special issue suggest that the regional tectonics, appearance of C(4) plants in East Africa, and late Cenozoic global cooling combined to produce a long-term drying trend in East Africa. Of particular importance is the uplift associated with the East African Rift Valley formation, which altered wind flow patterns from a more zonal to more meridinal direction. Results in this volume suggest a marked difference in the climate history of southern and eastern Africa, though both are clearly influenced by the major global climate thresholds crossed in the last 3 million years. Papers in this volume present lake, speleothem, and marine paleoclimate records showing that the East African long-term drying trend is punctuated by episodes of short, alternating periods of extreme wetness and aridity. These periods of extreme climate variability are characterized by the precession-forced appearance and disappearance of large, deep lakes in the East African Rift Valley and paralleled by low and high wind-driven dust loads reaching the adjacent ocean basins. Dating of these records show that over the last 3 million years such periods only occur at the times of major global climatic transitions, such as the intensification of Northern Hemisphere Glaciation (2.7-2.5 Ma), intensification of the Walker Circulation (1.9-1.7 Ma), and the Mid-Pleistocene Revolution (1-0.7 Ma). Authors in this volume suggest this onset occurs as high latitude forcing in both Hemispheres compresses the Intertropical Convergence Zone so that East Africa

  13. Paleoclimate Reconstruction of Guangxi in SW China during the Past 2000-Year: Stalagmite Records from Two Caves

    Science.gov (United States)

    Lien, W. Y.; Li, H. C.; Mii, H. S.

    2017-12-01

    Paleoclimate reconstructions help us to understand the role of the East Asian Summer Monsoon (EASM) on local precipitation and controlling factor of EASM variability, and to improve our climatic prediction. This study presents two stalagmite records from Jinlun Cave (23.553oN, 108.265oE) and Yilingyan Cave (23.041oN, 108.297oE) which are only 60 km apart in Guangxi Province, China. The 35-cm long stalagmite JL12 from Jinlun Cave and 10-cm long stalagmite YLY12 from Yilingyan Cave reveal 1500-year and 2000-year continuous growth respectively based on AMS 14C dating. Data points of the AMS 14C dates with the least dead carbon fraction (DCF) are used to build up the age model. Although dead carbons influence the 14C dating results, it is a feasible dating method for the stalagmites as 230Th/U dating on both stalagmites was not successful due to low U contents. A total of 1586 samples from JL12 and 948 samples from YLY12 have been done for stable isotopes analyses to serve as paleoclimate proxies. Comparison of the d18O records with the local rainfall records and the dry-wetness historic records shows the stalagmite d18O records as a rainfall proxy. The JL12 d18O record resembles the YLY12 d18O record in general, though some differences exist, which confirms the d18O records representing the local climate. The relatively lighter (lower) d18O values of the JL12 and YLY12 records during the Medieval Warm Period (MWP, AD900-1200) indicate stronger EASM. In the first phase of Little Ice Age (LIA), from AD1300 to AD1560, the d18O fluctuate drastically and the average during this period was lower, while the d18O was higher in the second phase of Little Ice Age (AD1560-AD1760), exhibiting a drier and stable climate in the second phase. Furthermore, the DCF varies through the stalagmite records, ascending during the LIA, descending during the MWP, which informs dry condition during the LIA and a moist climate in the MWP. Spectral analysis of the high-resolution d18O records

  14. Treating pre-instrumental data as "missing" data: using a tree-ring-based paleoclimate record and imputations to reconstruct streamflow in the Missouri River Basin

    Science.gov (United States)

    Ho, M. W.; Lall, U.; Cook, E. R.

    2015-12-01

    Advances in paleoclimatology in the past few decades have provided opportunities to expand the temporal perspective of the hydrological and climatological variability across the world. The North American region is particularly fortunate in this respect where a relatively dense network of high resolution paleoclimate proxy records have been assembled. One such network is the annually-resolved Living Blended Drought Atlas (LBDA): a paleoclimate reconstruction of the Palmer Drought Severity Index (PDSI) that covers North America on a 0.5° × 0.5° grid based on tree-ring chronologies. However, the use of the LBDA to assess North American streamflow variability requires a model by which streamflow may be reconstructed. Paleoclimate reconstructions have typically used models that first seek to quantify the relationship between the paleoclimate variable and the environmental variable of interest before extrapolating the relationship back in time. In contrast, the pre-instrumental streamflow is here considered as "missing" data. A method of imputing the "missing" streamflow data, prior to the instrumental record, is applied through multiple imputation using chained equations for streamflow in the Missouri River Basin. In this method, the distribution of the instrumental streamflow and LBDA is used to estimate sets of plausible values for the "missing" streamflow data resulting in a ~600 year-long streamflow reconstruction. Past research into external climate forcings, oceanic-atmospheric variability and its teleconnections, and assessments of rare multi-centennial instrumental records demonstrate that large temporal oscillations in hydrological conditions are unlikely to be captured in most instrumental records. The reconstruction of multi-centennial records of streamflow will enable comprehensive assessments of current and future water resource infrastructure and operations under the existing scope of natural climate variability.

  15. Human-provided waters for desert wildlife: What is the problem?

    Science.gov (United States)

    Mattson, D.J.; Chambers, N.

    2009-01-01

    Conflict persists in southwestern deserts of the United States over management of human-constructed devices to provide wildlife with water. We appraised decision processes in this case relative to the goal of human dignity and by the standards of civility and common interest outcomes. Our analysis suggested that conflict was scientized, rooted in worldviews, and aggravated by use of inflammatory symbols such as "wilderness" and "bighorn sheep." Contested problem definitions, framed as matters of science, advanced factional interests largely by allocating the burden of proof and failing to disclose private concerns about well-being, affection, respect, skill and power. Decision processes were shaped by precepts of scientific management, and thus largely failed to foster civility, common ground, and a focus on common interests, and instead tended to exacerbate deprivations of dignity and respect. If the status quo continues, we foresee further erosion of human dignity because there are likely to be increases in system stressors, such as climate change and human population growth. The prognosis would be more hopeful if alternatives were adopted that entailed authoritative, equitable, and collaborative public decision-making processes that took into consideration national-level common interests such as the U.S. Endangered Species Act. ?? Springer Science+Business Media, LLC. 2008.

  16. Moisture-driven xylogenesis in Pinus ponderosa from a Mojave Desert mountain reveals high phenological plasticity.

    Science.gov (United States)

    Ziaco, Emanuele; Truettner, Charles; Biondi, Franco; Bullock, Sarah

    2018-04-01

    Future seasonal dynamics of wood formation in hyperarid environments are still unclear. Although temperature-driven extension of the growing season and increased forest productivity are expected for boreal and temperate biomes under global warming, a similar trend remains questionable in water-limited regions. We monitored cambial activity in a montane stand of ponderosa pine (Pinus ponderosa) from the Mojave Desert for 2 consecutive years (2015-2016) showing opposite-sign anomalies between warm- and cold-season precipitation. After the wet winter/spring of 2016, xylogenesis started 2 months earlier compared to 2015, characterized by abundant monsoonal (July-August) rainfall and hyperarid spring. Tree size did not influence the onset and ending of wood formation, highlighting a predominant climatic control over xylem phenological processes. Moisture conditions in the previous month, in particular soil water content and dew point, were the main drivers of cambial phenology. Latewood formation started roughly at the same time in both years; however, monsoonal precipitation triggered the formation of more false rings and density fluctuations in 2015. Because of uncertainties in future precipitation patterns simulated by global change models for the Southwestern United States, the dependency of P. ponderosa on seasonal moisture implies a greater conservation challenge than for species that respond mostly to temperature conditions. © 2018 John Wiley & Sons Ltd.

  17. Plant responses to an edaphic gradient across an active sand dune/desert boundary in the great basin desert.

    NARCIS (Netherlands)

    Rosenthal, D.M.; Ludwig, F.; Donovan, L.A.

    2005-01-01

    In arid ecosystems, variation in precipitation causes broad-scale spatial heterogeneity in soil moisture, but differences in soil texture, development, and plant cover can also create substantial local soil moisture heterogeneity. The boundary between inland desert sand dunes and adjacent desert

  18. Evolutionary hotspots in the Mojave Desert

    Science.gov (United States)

    Vandergast, Amy G.; Inman, Richard D.; Barr, Kelly R.; Nussear, Kenneth E.; Esque, Todd C.; Hathaway, Stacie A.; Wood, Dustin A.; Medica, Philip A.; Breinholt, Jesse W.; Stephen, Catherine L.; Gottscho, Andrew D.; Marks, Sharyn B.; Jennings, W. Bryan; Fisher, Robert N.

    2013-01-01

    Genetic diversity within species provides the raw material for adaptation and evolution. Just as regions of high species diversity are conservation targets, identifying regions containing high genetic diversity and divergence within and among populations may be important to protect future evolutionary potential. When multiple co-distributed species show spatial overlap in high genetic diversity and divergence, these regions can be considered evolutionary hotspots. We mapped spatial population genetic structure for 17 animal species across the Mojave Desert, USA. We analyzed these in concurrence and located 10 regions of high genetic diversity, divergence or both among species. These were mainly concentrated along the western and southern boundaries where ecotones between mountain, grassland and desert habitat are prevalent, and along the Colorado River. We evaluated the extent to which these hotspots overlapped protected lands and utility-scale renewable energy development projects of the Bureau of Land Management. While 30–40% of the total hotspot area was categorized as protected, between 3–7% overlapped with proposed renewable energy project footprints, and up to 17% overlapped with project footprints combined with transmission corridors. Overlap of evolutionary hotspots with renewable energy development mainly occurred in 6 of the 10 identified hotspots. Resulting GIS-based maps can be incorporated into ongoing landscape planning efforts and highlight specific regions where further investigation of impacts to population persistence and genetic connectivity may be warranted.

  19. Landscape Sustainability in a Sonoran Desert City

    Directory of Open Access Journals (Sweden)

    Chris A. Martin

    2008-01-01

    Full Text Available The objective of this paper is to discuss concepts of landscape sustainability in the Phoenix metropolitan area. Phoenix is situated in the greater Salt River Valley of the lower Sonoran Desert in the southwest United States. In this paper I use the ecological frameworks of ecosystem services and resiliency as a metric for understanding landscape sustainability. An assessment of landscape sustainability performance benchmarks were made by surveying research findings of scientists affiliated with the Central Arizona Phoenix Long Term Ecological Research Project (CAP LTER. In Phoenix, present day emphases on cultural, aesthetic, and habitat formation ecosystem services within an arid ecoregion of low natural resilience coupled to a complex matrix of socioeconomic stratification, excessive landscape water use and pruning practices has had the undesired effect of degrading landscape sustainability. This has been measured as mixed patterns of plant diversity and human-altered patterns of carbon regulation, microclimate control, and trophic dynamics. In the future, sustainable residential landscaping in desert cities such as Phoenix may be fostered through use of water-conserving irrigation technologies, oasis-style landscape design motifs, recycling of landscape green waste, and conservative plant pruning strategies.

  20. Airborne particle accumulation and composition at different locations in the northern Negev desert.

    NARCIS (Netherlands)

    Offer, Z.Y.; Goossens, D.

    2001-01-01

    Atmospheric desert dust was collected over 36 months in ground-level collectors at four stations in the northern Negev desert, Israel. Three stations (Shivta, Sede Boqer and Avdat) are located in the desert itself whereas the fourth station (Sayeret Shaked) is situated at the desert fringe, in the

  1. The greening of the McGill Paleoclimate Model. Part I: Improved land surface scheme with vegetation dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi; Mysak, Lawrence A.; Wang, Zhaomin [McGill University, Department of Atmospheric and Oceanic Sciences, Global Environmental and Climate Change Centre (GEC3), Montreal, QC (Canada); Brovkin, Victor [Potsdam Institute for Climate Impact Research (PIK), Potsdam (Germany)

    2005-04-01

    The formulation of a new land surface scheme (LSS) with vegetation dynamics for coupling to the McGill Paleoclimate Model (MPM) is presented. This LSS has the following notable improvements over the old version: (1) parameterization of deciduous and evergreen trees by using the model's climatology and the output of the dynamic global vegetation model, VECODE (Brovkin et al. in Ecological Modelling 101:251-261 (1997), Global Biogeochemical Cycles 16(4):1139, (2002)); (2) parameterization of tree leaf budburst and leaf drop by using the model's climatology; (3) parameterization of the seasonal cycle of the grass leaf area index; (4) parameterization of the seasonal cycle of tree leaf area index by using the time-dependent growth of the leaves; (5) calculation of land surface albedo by using vegetation-related parameters, snow depth and the model's climatology. The results show considerable improvement of the model's simulation of the present-day climate as compared with that simulated in the original physically-based MPM. In particular, the strong seasonality of terrestrial vegetation and the associated land surface albedo variations are in good agreement with several satellite observations of these quantities. The application of this new version of the MPM (the ''green'' MPM) to Holocene millennial-scale climate changes is described in a companion paper, Part II. (orig.)

  2. Late Cretaceous paleosols as paleoclimate proxies of high-latitude Southern Hemisphere: Mata Amarilla Formation, Patagonia, Argentina

    Science.gov (United States)

    Varela, Augusto N.; Raigemborn, M. Sol; Richiano, Sebastián; White, Tim; Poiré, Daniel G.; Lizzoli, Sabrina

    2018-01-01

    Although there is general consensus that a global greenhouse climate characterized the mid-Cretaceous, details of the climate state of the mid-Cretaceous Southern Hemisphere are less clearly understood. In particular, continental paleoclimate reconstructions are scarce and exclusively derived from paleontological records. Using paleosol-derived climofunction studies of the mid- to Upper Cretaceous Mata Amarilla Formation, southern Patagonia, Argentina, we present a reconstruction of the mid-Cretaceous climate of southern South America. Our results indicate that at 60° south paleolatitude during the Cenomanian-Santonian stages, the climate was subtropical temperate-warm (12 °C ± 2.1 °C) and humid (1404 ± 108 mm/yr) with marked rainfall seasonality. These results are consistent with both previous estimations from the fossil floras of the Mata Amarilla Formation and other units of the Southern Hemisphere, and with the previous observations of the displacement of tropical and subtropical floras towards the poles in both hemispheres. The data presented here show a more marked seasonality and slightly lower mean annual precipitation and mean annual temperature values than those recorded at the same paleolatitudes in the Northern Hemisphere.

  3. Seven Global Goals. 2013 annual report, Southwestern Power Administration

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2014-09-01

    For over 70 years, Southwestern has marketed and delivered reliable, renewable, and affordable hydropower, partnering with Federal power stakeholders and others in the industry to make sure the lights stay on. This kind of effective, efficient, and cost conscious operation is made possible only by hard work and dedication. Southwestern employees work individually and as a team to meet seven comprehensive agency goals that touch on all aspects of the agency’s operations. Dubbed the “Seven Global Goals” by Administrator Chris Turner, these objectives identify specific, measurable targets that support Southwestern’s mission and reinforce its responsibilities toward its customers and the Nation.

  4. Southwestern Avian Community Organization in Exotic Tamarix: Current Patterns and Future Needs

    Science.gov (United States)

    H. A. Walker

    2006-01-01

    Tamarisk (saltcedar: Tamarix), an invasive exotic tree native to the Eastern Hemisphere, is currently the dominant plant species in most southwestern riparian ecosystems at elevations below 1500 m. Tamarisk alters abiotic conditions and the floral composition of native southwestern riparian ecosystems and, in turn, affects native southwestern animal communities....

  5. The energy behind the power. Southwestern Power Administration 1994 annual report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    This is the Southwestern Power Administration 1994 annual report. The topics of the report include a letter to the secretary; an overview including the mission statement, a description of the Southwestern Federal Power System, financial statement, performance measurements, national performance review; year in review, summary of results, financial and statistical data and the Southwestern Power Administration Organization.

  6. Paleoclimate Reconstruction during the 17th to 18th Century Using Fossil Coral Tsunami Boulders from Ishigaki Island, the Ryukyus, Japan

    Science.gov (United States)

    Tsuzuki, K.; Yokoyama, Y.; Seki, A.; Kawakubo, Y.; Araoka, D.; Suzuki, A.

    2014-12-01

    Little Ice Age (LIA) which lasted during approximately 1450 to 1850 (e.g. Grove, 1988) is known as naturally occurring climate fluctuation, so knowing LIA in detail is necessary to improve climate models. Instrumental records can only extend back to about 100 years in many areas, thus paleoclimate records are reconstructed using proxies in tree rings, sediments and so force. However there are differences in reconstructed timings and magnitudes of LIA occurred in each area (Overpack et al., 1997), and most of the records are based mainly on terrestrial proxies such as tree ring records, whereas only limited numbers of marine records are available (Mann et al., 2008). Coral skeletal climatology is a useful tool to reconstruct marine paleoclimate records in tropics and subtropics. Hermatypic corals, Porites spp. have aragonite skeletons and they have annual bands, which are suitable to reconstruct high-resolution paleoclimate in seasonal scale by measuring chemical compositions. Skeletal Sr/Ca ratio in Porites spp. has been widely used as a reliable proxy of SST (Sea Surface Temperature). However, corals grow for approximately several decades to 200 years, hence it is difficult to reconstruct LIA paleoclimate using living corals. Cobb et al. (2003) used fossil corals casted on shore by storms to reconstruct millennial scale paleoclimate. There are fossil coral boulders in the eastern coast of Ishigaki Island, Ryukyus, Japan. These fossil coral boulders were casted on shore by paleo Tsunami events, thus they are called "Tsunami boulders" (Araoka et al., 2010). Fossil corals used by Cobb et al. have 30-90-year records while some large Tsunami boulders have multi-centennial continuous records. In this study, we reconstruct paleo SST using the Tsunami boulder from Ishigaki Island. The boulder has 185 years of annual banding. U-series dating shows the boulder was moved on shore at Meiwa earthquake in 1771. We measure Sr/Ca ratio using LA-HR-ICPMS (Laser Ablation High

  7. Floods of December 1966 in southwestern Utah

    Science.gov (United States)

    Butler, Elmer; Mundorff, J.C.

    1970-01-01

    Severe floods occurred in parts of southwestern Utah on December 5-6, 1966, as a result of precipitation of about 1 inch to more than 12 inches during December 3-6. The flood on the Virgin River was the greatest since the first settlers arrived in 1860.The peak discharge of the Virgin River at Virgin, Utah, was 22,830 cubic feet per second on December 6; this exceeded the previous maximum discharge of 13,500 cubic feet per second on March 3, 1938, and September 17, 1961, and probably has a recurrence interval of 100 years. At eight other gage sites in the flood area, the peak discharge in December 1966 was the highest of record; the recurrence intervals of some of the peak discharges may be 100 years. The flood peaks were generally of short duration and most streams receded to near base flow within 24 hours.The dissolved-solids content was significantly lower in the Virgin River at Virgin than at St. George, about 25 miles downstream; the water was of the calcium sulfate type at both sites. Data for the Santa Clara River above Winsor Dam and the Santa Clara River near Santa Clara show a significant increase in dissolved solids between the two sites. The water above Winsor Dam was of the calcium bicarbonate type, and the water near Santa Clara was of the calcium bicarbonate sulfate type.The suspended-sediment discharge, during the period December 5-8, 1966, at Santa Clara River above Winsor Dam, near Santa Clara was about foyer times greater than all the suspended-sediment discharge during the preceding 3 years ; the suspended-sediment discharge of the Virgin River at Virgin was greater during the 4-day period than during any one of the preceding 3 years.Nearly all the flood damage in the area occurred in the Virgin River basin. According to the Soil Conservation Service, total damage in the Dixie Soil Conservation District in Washington County was about $835,000; 60 percent of the damage was caused by floodwater and 40 percent by deposited sediment.

  8. Regional and climatic controls on seasonal dust deposition in the southwestern U.S.

    Science.gov (United States)

    Reheis, M.C.; Urban, F.E.

    2011-01-01

    Vertical dust deposition rates (dust flux) are a complex response to the interaction of seasonal precipitation, wind, changes in plant cover and land use, dust source type, and local vs. distant dust emission in the southwestern U.S. Seasonal dust flux in the Mojave-southern Great Basin (MSGB) deserts, measured from 1999 to 2008, is similar in summer-fall and winter-spring, and antecedent precipitation tends to suppress dust flux in winter-spring. In contrast, dust flux in the eastern Colorado Plateau (ECP) region is much larger in summer-fall than in winter-spring, and twice as large as in the MSGB. ECP dust is related to wind speed, and in the winter-spring to antecedent moisture. Higher summer dust flux in the ECP is likely due to gustier winds and runoff during monsoonal storms when temperature is also higher. Source types in the MSGB and land use in the ECP have important effects on seasonal dust flux. In the MSGB, wet playas produce salt-rich dust during wetter seasons, whereas antecedent and current moisture suppress dust emission from alluvial and dry-playa sources during winter-spring. In the ECP under drought conditions, dust flux at a grazed-and-plowed site increased greatly, and also increased at three annualized, previously grazed sites. Dust fluxes remained relatively consistent at ungrazed and currently grazed sites that have maintained perennial vegetation cover. Under predicted scenarios of future climate change, these results suggest that an increase in summer storms may increase dust flux in both areas, but resultant effects will depend on source type, land use, and vegetation cover. ?? 2011.

  9. Stable isotope systematics in mesozoic granites of Central and Northern California and Southwestern Oregon

    Science.gov (United States)

    Masi, U.; O'Neil, J.R.; Kistler, R.W.

    1981-01-01

    18O, D, and H2O+ contents were measured for whole-rock specimens of granitoid rocks from 131 localitics in California and southwestern Oregon. With 41 new determinations in the Klamath Mountains and Sierra Nevada, initial strontium isotope ratios are known for 104 of these samples. Large variations in ??18O (5.5 to 12.4), ??D (-130 to -31), water contents (0.14 to 2.23 weight percent) and initial strontium isotope ratios (0.7028 to 0.7095) suggest a variety of source materials and identify rocks modified by secondary processes. Regular patterns of variation in each isotopic ratio exist over large geographical regions, but correlations between the ratios are generally absent except in restricted areas. For example, the regular decrease in ??D values from west to east in the Sierra Nevada batholith is not correlative with a quite complex pattern of ??18O values, implying that different processes were responsible for the isotopic variations in these two elements. In marked contrast to a good correlation between (87Sr/86Sr)o and ??18O observed in the Peninsular Ranges batholith to the south, such correlations are lacking except in a few areas. ??D values, on the other hand, correlate well with rock types, chemistry, and (87Sr/86Sr)o except in the Coast Ranges where few of the isotopic signatures are primary. The uniformly low ??D values of samples from the Mojave Desert indicate that meteoric water contributed much of the hydrogen to the rocks in that area. Even so, the ??18O values and 18O fractionations between quartz and feldspar are normal in these same rocks. This reconnaissance study has identified regularities in geochemical parameters over enormous geographical regions. These patterns are not well understood but merit more detailed examination because they contain information critical to our understanding of the development of granitoid batholiths. ?? 1981 Springer-Verlag.

  10. Water sources for cyanobacteria below desert rocks in the Negev Desert determined by conductivity

    OpenAIRE

    McKay, Christopher P.

    2016-01-01

    We present year round meteorological and conductivity measurements of colonized hypolithic rocks in the Arava Valley, Negev Desert, Israel. The data indicate that while dew is common in the Negev it is not an important source of moisture for hypolithic organisms at this site. The dominance of cyanobacteria in the hypolithic community is consistent with predictions that cyanobacteria are confined to habitats supplied by rain. To monitor the presence of liquid water under the small Negev rocks ...

  11. Integrating Army Aviation into the Combined Arms Team: Operational Art in Desert Shield and Desert Storm

    Science.gov (United States)

    2017-05-25

    King of Saudi Arabia. The conversation took place prior to an Organization of the Petroleum Exporting Countries (OPEC) meeting of Arab Gulf members...Blumberg and Christopher C. French, eds., The Persian Gulf War: Views from the Social and Behavioral Sciences (Lanham, MD: University Press of America...1994), 17. 72 Blumberg and French, The Persian Gulf War, 29. 20 building up forces in northeast Saudi Arabia during Operation Desert Shield, in

  12. In vitro germination of desert rose varieties(

    Directory of Open Access Journals (Sweden)

    Tatiane Lemos Varella

    2015-08-01

    Full Text Available The drought stress resistance is a characteristic of the desert rose and its estimable beauty flowers, which gave it great relevance in the ornamental market. However, the desert rose production and germination is hampered by possible sterility of their male and female flowers and frequent problems in pollination, so the tissue culture is a promising alternative to the propagation of these plants. This study aimed to evaluate the effect of gibberellic acid on four commercial varieties of desert rose (Adenium obesum cultivated in vitro. The seeds of the varieties ‘Orange Pallet’, ‘Carnation violet’, ‘Diamond ring’ and ‘Vermiliont’ were sterilized and inoculated on Water + Agar (T0, medium MS (T1, ½ MS (T2, MS + 0.25 mg L-1 GA3 (T3, MS + 0.5 mg L-1 GA3 (T4, ½ MS + 0.25 mg L-1 GA3 (T5, ½ MS 0.5 mg L-1 GA3 (T6. The seeds germination of A. obesum was initiated on the fourth day of cultivation and on the tenth day was possible to observe the expansion of the cotyledons and leaf expansion with subsequent development of early secondary root. The ‘Orange pallet’ variety germinated 100% of seeds on water + agar and MS ½ + 0.5 mg L-1 of GA3. For ‘Diamond Ring’ and ‘Carnation violet’ the highest rate of germination occurred in treatments MS ½; 0.25 mg L-1 GA3; MS + 0.5 mg L-1 GA3 MS ½ + 0.5 mg L-1 GA3 averaging 80% and 70%, respectively. For ‘Vermiliont’ the best response was in MS and MS ½ + 0.5 mg L-1 GA3 ranging between 70-90% germinated embryos. It was registered different malformations in all treatments like absence of roots and apexes during seedling development. The concentrations of GA3 did not affect significantly the seed germination.

  13. Properties of Desert Sand and CMAS Glass

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2014-01-01

    As-received desert sand from a Middle East country has been characterized for its phase composition and thermal stability. X-ray diffraction analysis showed the presence of quartz (SiO2), calcite (CaCO3), gypsum (CaSO4.2H2O), and NaAlSi3O8 phases in as-received desert sand and showed weight loss of approx. 35 percent due to decomposition of CaCO3 and CaSO4.2H2O when heated to 1400 C. A batch of as-received desert sand was melted into calcium magnesium aluminosilicate (CMAS) glass at approx. 1500 C. From inductively coupled plasma-atomic emission spectrometry, chemical composition of the CMAS glass was analyzed to be 27.8CaO-4MgO-5Al2O3-61.6SiO2-0.6Fe2O3-1K2O (mole percent). Various physical, thermal and mechanical properties of the glass have been evaluated. Bulk density of CMAS glass was 2.69 g/cc, Young's modulus 92 GPa, Shear modulus 36 GPa, Poisson's ratio 0.28, dilatometric glass transition temperature (T (sub g)) 706 C, softening point (T (sub d)) 764 C, Vickers microhardness 6.3 +/- 0.4 GPa, indentation fracture toughness 0.75 +/- 0.15 MPa.m (sup 1/2), and coefficient of thermal expansion (CTE) 9.8 x 10 (exp -6)/degC in the temperature range 25 to 700 C. Temperature dependence of viscosity has also been estimated from various reference points of the CMAS glass using the Vogel-Fulcher-Tamman (VFT) equation. The glass remained amorphous after heat treating at 850 C for 10 hr but crystallized into CaSiO3 and Ca-Mg-Al silicate phases at 900 C or higher temperatures. Crystallization kinetics of the CMAS glass has also been investigated by differential thermal analysis (DTA). Activation energies for the crystallization of two different phases in the glass were calculated to be 403 and 483 kJ/mol, respectively.

  14. Chemical constituents of Cenchrus ciliaris L. from the Cholistan desert, Pakistan

    OpenAIRE

    Ashraf Muhammad Aqeel; Mahmood Karamat; Yusoff Ismail; Qureshi Ahmad Kaleem

    2013-01-01

    The Cholistan Desert is an extension of the Great Indian Desert, covering an area of 26,330 km2. The desert can be divided into two main geomorphic regions: the northern region, known as Lesser Cholistan, constituting the desert margin and consisting of a series of saline alluvial flats alternating with low sand ridges/dunes; and the southern region, known as Greater Cholistan, a wind-resorted sandy desert comprised of a number of old Hakra River terraces w...

  15. Fog deposition to the Atacama desert

    Science.gov (United States)

    Westbeld, A.; Klemm, O.; Griessbaum, F.; Sträter, E.; Larrain, H.; Osses, P.; Cereceda, P.

    2010-07-01

    In the Atacama Desert, one of the driest places on earth, fog deposition plays an important role for the water balance and for the survival of vulnerable ecosystems. The eddy covariance method, previously applied for the quantification of fog deposition to forests in various parts of the world, was used for the first time to measure deposition of fog water to a desert. We estimated the amount of water available for the ecosystem by deposition and determined the relevant processes driving fog deposition. This is especially important for the species Tillandsia landbecki living in coastal Atacama at the limit of plant existence with fog and dew being the only sources of liquid water. Between 31 July and 19 August, 2008, measurements were realized in a 31 ha large Tillandsia carpet at Cerro Guanaco, located 15 km south of Iquique, northern Chile. Several data quality assurance procedures were applied. For the values in compliance with the applied criteria, the mean total deposition per hour was determined (0.04 L per m2) for foggy periods. This number was applied to estimate the amount of water deposited during the measuring period, during the entire month of August 2008, and throughout a whole year. For August 2008, a frequency of fog of 16 %, as established during the measuring period, was assumed. The frequency for a whole year was estimated from the differences of the collected amount of water obtained with standard fog collectors installed at Cerro Guanaco in an earlier study. Calculations resulted in an amount of 2.5 L per m2 of deposited fog water for the measuring period. During the entire August, 4.4 L per m2 have likely been available, and for a whole year, a total of 25 L per m2 was estimated to have reached the surface. Inaccuracies could have been caused by the low amount of data applied, and by a possible underestimation of the deposition due to additional formation of radiation fog during the fog events. Three days were used for further analysis because

  16. Desert ants learn vibration and magnetic landmarks.

    Directory of Open Access Journals (Sweden)

    Cornelia Buehlmann

    Full Text Available The desert ants Cataglyphis navigate not only by path integration but also by using visual and olfactory landmarks to pinpoint the nest entrance. Here we show that Cataglyphis noda can additionally use magnetic and vibrational landmarks as nest-defining cues. The magnetic field may typically provide directional rather than positional information, and vibrational signals so far have been shown to be involved in social behavior. Thus it remains questionable if magnetic and vibration landmarks are usually provided by the ants' habitat as nest-defining cues. However, our results point to the flexibility of the ants' navigational system, which even makes use of cues that are probably most often sensed in a different context.

  17. Phylogeographic and population genetic structure of bighorn sheep ( Ovis canadensis ) in North American deserts.

    Science.gov (United States)

    Buchalski, Michael R; Sacks, Benjamin N; Gille, Daphne A; Penedo, Maria Cecilia T; Ernest, Holly B; Morrison, Scott A; Boyce, Walter M

    2016-06-09

    Fossil data are ambiguous regarding the evolutionary origin of contemporary desert bighorn sheep ( Ovis canadensis subspecies). To address this uncertainty, we conducted phylogeographic and population genetic analyses on bighorn sheep subspecies found in southwestern North America. We analyzed 515 base pairs of mtDNA control region sequence and 39 microsatellites in 804 individuals from 58 locations. Phylogenetic analyses revealed 2 highly divergent clades concordant with Sierra Nevada ( O. c. sierrae ) and Rocky Mountain ( O. c. canadensis ) bighorn and showed that these 2 subspecies both diverged from desert bighorn prior to or during the Illinoian glaciation (~315-94 thousand years ago [kya]). Desert bighorn comprised several more recently diverged haplogroups concordant with the putative Nelson ( O. c. nelsoni ), Mexican ( O. c. mexicana ), and Peninsular ( O. c. cremnobates ) subspecies. Corresponding estimates of effective splitting times (~17-3 kya), and haplogroup ages (~85-72 kya) placed the most likely timeframe for divergence among desert bighorn subspecies somewhere within the last glacial maximum. Median-joining haplotype network and Bayesian skyline analyses both indicated that desert bighorn collectively comprised a historically large and haplotype-diverse population, which subsequently lost much of its diversity through demographic decline. Using microsatellite data, discriminant analysis of principle components (DAPC) and Bayesian clustering analyses both indicated genetic structure concordant with the geographic distribution of 3 desert subspecies. Likewise, microsatellite and mitochondrial-based F ST comparisons revealed significant fixation indices among the desert bighorn genetic clusters. We conclude these desert subspecies represent ancient lineages likely descended from separate Pleistocene refugial populations and should therefore be managed as distinct taxa to preserve maximal biodiversity. Los datos de fósiles sobre el origen evolutivo

  18. What drives low-severity fire in the southwestern USA?

    Science.gov (United States)

    Sean A. Parks; Solomon Z. Dobrowski; Matthew H. Panunto

    2018-01-01

    Many dry conifer forests in the southwestern USA and elsewhere historically (prior to the late 1800’s) experienced fairly frequent surface fire at intervals ranging from roughly five to 30 years. Due to more than 100 years of successful fire exclusion, however, many of these forests are now denser and more homogenous, and therefore they have a greater probability of...

  19. Strategic nutrient management of field pea in southwestern Uganda ...

    African Journals Online (AJOL)

    Strategic nutrient management of field pea in southwestern Uganda. ... African Journal of Food, Agriculture, Nutrition and Development ... Strategic nutrient management requires that the most limiting nutrient is known in order to provide a foundation for designing effective and sustainable soil fertility management ...

  20. Morphological pattern of endometrial biopsies in southwestern Nigeria

    African Journals Online (AJOL)

    Background: Endometrium remains the most sensitive indicator of ovarian function and endometrial biopsy is one of the diagnostic procedures in endometrial pathology. The current study was carried out to examine the morphological pattern of endometrial biopsies in Ibadan, South-western Nigeria and compare the results ...

  1. Fire and birds in the southwestern United States

    Science.gov (United States)

    Carl E. Bock; William M. Block

    2005-01-01

    Fire is an important ecological force in many southwestern ecosystems, but frequencies, sizes, and intensities of fire have been altered historically by grazing, logging, exotic vegetation, and suppression. Prescribed burning should be applied widely, but under experimental conditions that facilitate studying its impacts on birds and other components of biodiversity....

  2. A plan for landscape fire restoration in the Southwestern Borderlands

    Science.gov (United States)

    Gerald J. Gottfried; Larry S. Allen

    2009-01-01

    Fires were prevalent in the Southwestern Borderlands of Arizona and New Mexico prior to the arrival of European-American settlers in the 1880s. The almost total exclusion of fires for more than 100 years has been linked to declines in biological diversity and a loss of productivity associated with the encroachment of woody vegetation into the grasslands and open...

  3. Hydrology of southwestern encinal oak ecosystems: A review and more

    Science.gov (United States)

    Gerald J. Gottfried; Peter F. Ffolliott; Daniel G. Neary

    2007-01-01

    Information about the hydrology of oak ecosystems of the southwestern United States and northern Mexico is lacking (Lopes and Ffolliott 1992, Baker et al. 1995) even though the woodlands and savannas cover more than 31,000 square miles. These ecosystems generally are found between 4,000 and 7,300 feet in elevation. Precipitation occurs in the winter and summer and...

  4. Silviculture of southwestern ponderosa pine: The status of our knowledge

    Science.gov (United States)

    Gilbert H. Schubert

    1974-01-01

    Describes the status of our knowledge of ponderosa pine silviculture in the southwestern States of Arizona, Colorado, New Mexico, and Utah. Economic value, impact on other uses, and the timber resource are discussed first, followed by ecological background, site quality, growth and yield, and silviculture and management. Relevant literature is discussed along with...

  5. A review of maternal mortality at Jimma Hospital, Southwestern ...

    African Journals Online (AJOL)

    A retrospective review of hospital maternal deaths at Jimma Hospital, Southwestern Ethiopia, covering the period from September 1990 to May 1999 was conducted with the objectives of determining the overall maternal mortality rate, observing trend of maternal mortality during the period, and identifying major causes of ...

  6. Silvics and silviculture in the southwestern pinyon-juniper woodlands

    Science.gov (United States)

    Gerald J. Gottfried

    2004-01-01

    Southwestern pinyon-juniper and juniper woodlands cover large areas of the western United States. The woodlands have been viewed as places of beauty and sources of valuable resource products or as weed-dominated landscapes that hinder the production of forage for livestock. They are special places because of the emotions and controversies that encircle their management...

  7. Analysis of Culex and Aedes mosquitoes in southwestern Nigeria ...

    African Journals Online (AJOL)

    Introduction: Amplification and transmission of West Nile virus (WNV) by mosquitoes are driven by presence and number of viraemic/susceptible avian hosts. Methods: in order to predict risk of WNV infection to humans, we collected mosquitoes from horse stables in Lagos and Ibadan, southwestern Nigeria. The mosquitoes ...

  8. Carbon and nitrogen cycling in southwestern ponderosa fine forests

    Science.gov (United States)

    Stephen C. Hart; Paul C. Selmants; Sarah I. Boyle; Steven T. Overby

    2007-01-01

    Ponderosa pine forests of the southwestern United States were historically characterized by relatively open, parklike stands with a bunchgrass-dominated understory. This forest structure was maintained by frequent, low-intensity surface fires. Heavy livestock grazing, fire suppression, and favorable weather conditions following Euro-American settlement in the late 19th...

  9. Upland hardwood habitat types in southwestern North Dakota

    Science.gov (United States)

    Michele M. Girard; Harold Goetz; Ardell J. Bjugstad

    1985-01-01

    The Daubenmire habitat type method was used to classify the upland hardwood draws of southwestern North Dakota. Preliminary data analysis indicates there are four upland habitat types: Fraxinus pennsylvanica/Prunus virginiana; F. pnnseanica-Ulmus americana/P. virginiana; Populus...

  10. Recent emissions research in southwestern shrub and grassland fuels

    Science.gov (United States)

    David R. Weise; Wayne Miller; David R. Cocker; Heejung Jung; Seyedehsan Hosseini; Marko Princevac; Robert J. Yokelson; Ian Burling; Sheryl Akagi; Shawn Urbanski; WeiMin Hao

    2015-01-01

    While it is currently challenging to use prescribed burning in chaparral and other southwestern shrub fuel types due to many constraints, any such activities require smoke management planning. Information on fuels and emissions from chaparral were limited and based on older sampling systems. The DoD SERDP program funded a project to measure fuels and smoke emissions in...

  11. Cancer distribution pattern in south-western Nigeria | Awodele ...

    African Journals Online (AJOL)

    The burden of cancer in Nigeria is appreciable with about 100,000 new cancer cases been reported in the country each year. This study aimed to determine the level of occurrence and pattern of distribution of different cancer types in two major functional cancer registries in south-western Nigeria. A desk review of the level ...

  12. Estimation of the lion ( Panthera leo ) population in the southwestern ...

    African Journals Online (AJOL)

    A previous estimate of the lion (Panthera leo) population in the southwestern Kgalagadi Transfrontier Park (KTP) was made over 20 years ago. This together with increased fears regarding the viability of the population as a result of recent killings of roaming animals, an observed increase in non-violent mortalities during ...

  13. 2014 annual site environmental report, Southwestern Power Administration

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2014-12-31

    Southwestern Power Administration’s Annual Site Environmental Report (ASER) serves as the chief reporting mechanism for site environmental performance information within the Department of Energy and as a valuable resource for shared and collaborative environmental protection and performance information to Agency stakeholders and members of the public living near Southwestern Power Administration’s (Southwestern) facilities and transmission line rights-of-ways. This ASER meets the requirements of Department of Energy (DOE) Order 231.B. Southwestern’s key environmental involvement includes an emphasis on the protection of ecological resources which is effectively accomplished through environmental program elements such as protecting water resources, generation of clean hydropower energy, oil spill prevention practices, elimination of green-house gas emissions, and comprehensive project reviews to ensure the protection of living organisms, migratory birds, Federally threatened or endangered species, and historic or cultural resources. Southwestern continues to actively minimize effects to natural resources and strive for continual improvement in the area of environmental compliance and sustainability while achieving the agency mission to market and deliver Federal hydroelectric power.

  14. Fragmentation patterns of evergreen oak woodlands in Southwestern Iberia

    DEFF Research Database (Denmark)

    Costa, A.; Madeira, M.; Lima Santos, J.

    2014-01-01

    Mediterranean evergreen oak woodlands (composed of Quercus suber L. and Quercus rotundifolia Lam.) are becoming increasingly fragmented in the human-modified landscapes of Southwestern Portugal and Spain. Previous studies have largely neglected to assess the spatial changes of oak woodlands...... patterns of oak recruitment and therefore, its study may be helpful in highlighting future baselines for the sustainable management of oak woodlands....

  15. Prevalence of Infertility in Women in a Southwestern Nigerian ...

    African Journals Online (AJOL)

    The prevalence and common causes of infertility in women aged between 15 and 55 years was assessed in four hospital centers in Osun State, located in the SouthWestern part of Nigeria. A survey of a consecutive sample of 200 cases of infertility were carried out in four hospital centers with a total of 50 cases of infertility ...

  16. Investigating water resources of the desert: How isotopes can help

    International Nuclear Information System (INIS)

    Gonfiantini, R.

    1992-01-01

    Newspapers and magazines from time to time write about the enormous reserves of water stored underground in the Sahara, whose rational exploitation would allow the agricultural development of the desert. Although the practical implementation of such projects is rather problematic, it is true that groundwater is relatively abundant under most of the Sahara (as well as in other deserts in the world), but it is seldom easily accessible. What do we really know about these resources of groundwater and how they have accumulated in areas where rainfall is so scarce. What do we know of the hydrological history of the desert. These problems are important for the correct evaluation and use of the groundwater in the desert. Isotope techniques help in their solution, and are described in this document. 6 figs

  17. Investigating water resources of the desert: how isotopes can help

    International Nuclear Information System (INIS)

    Gonfiantini, R.

    1981-01-01

    Newspapers and magazines from time to time write about the enormous reserves of water stored underground in the Sahara, whose rational exploitation would allow the agricultural development of the desert. Although the practical implementation of such projects is rather problematic, it is true that groundwater is relatively abundant under most of the Sahara (as well as in other deserts in the world), but it is seldom easily accessible. What do we really know about these resources of groundwater and how they have accumulated in areas where rainfall is so scarce. What do we know of the hydrological history of the desert. These problems are important for the correct evaluation and use of the groundwater in the desert. Isotope techniques help in their solution, and are described in this document

  18. Vegetation - Anza-Borrego Desert State Park [ds165

    Data.gov (United States)

    California Natural Resource Agency — The Anza Borrego Desert State Park (ABDSP) Vegetation Map depicts vegetation within the Park and its surrounding environment. The map was prepared by the Department...

  19. The potential of energy farming in the southeastern California desert

    Science.gov (United States)

    Lew, V.

    1980-04-01

    The use of energy forms to provide future sources of energy for California is considered. Marginal desert lands in southeastern California are proposed for the siting of energy farms using acacia, eucalyptus, euphorbia, guayule, jojoba, mesquite, or tamarisk.

  20. Modeling Agassiz's Desert Tortoise Population Response to Anthropogenic Stressors

    Science.gov (United States)

    Mojave Desert tortoise (Gopherus agassizii) populations are exposed to a variety of anthropogenic threats, which vary in nature, severity, and frequency. Tortoise management in conservation areas can be compromised when the relative importance of these threats is not well underst...

  1. Camelid genomes reveal evolution and adaptation to desert environments.

    Science.gov (United States)

    Wu, Huiguang; Guang, Xuanmin; Al-Fageeh, Mohamed B; Cao, Junwei; Pan, Shengkai; Zhou, Huanmin; Zhang, Li; Abutarboush, Mohammed H; Xing, Yanping; Xie, Zhiyuan; Alshanqeeti, Ali S; Zhang, Yanru; Yao, Qiulin; Al-Shomrani, Badr M; Zhang, Dong; Li, Jiang; Manee, Manee M; Yang, Zili; Yang, Linfeng; Liu, Yiyi; Zhang, Jilin; Altammami, Musaad A; Wang, Shenyuan; Yu, Lili; Zhang, Wenbin; Liu, Sanyang; Ba, La; Liu, Chunxia; Yang, Xukui; Meng, Fanhua; Wang, Shaowei; Li, Lu; Li, Erli; Li, Xueqiong; Wu, Kaifeng; Zhang, Shu; Wang, Junyi; Yin, Ye; Yang, Huanming; Al-Swailem, Abdulaziz M; Wang, Jun

    2014-10-21

    Bactrian camel (Camelus bactrianus), dromedary (Camelus dromedarius) and alpaca (Vicugna pacos) are economically important livestock. Although the Bactrian camel and dromedary are large, typically arid-desert-adapted mammals, alpacas are adapted to plateaus. Here we present high-quality genome sequences of these three species. Our analysis reveals the demographic history of these species since the Tortonian Stage of the Miocene and uncovers a striking correlation between large fluctuations in population size and geological time boundaries. Comparative genomic analysis reveals complex features related to desert adaptations, including fat and water metabolism, stress responses to heat, aridity, intense ultraviolet radiation and choking dust. Transcriptomic analysis of Bactrian camels further reveals unique osmoregulation, osmoprotection and compensatory mechanisms for water reservation underpinned by high blood glucose levels. We hypothesize that these physiological mechanisms represent kidney evolutionary adaptations to the desert environment. This study advances our understanding of camelid evolution and the adaptation of camels to arid-desert environments.

  2. Desert Peak East Enhanced Geothermal Systems (EGS) Project

    Energy Technology Data Exchange (ETDEWEB)

    Zemach, Ezra [Ormat Technologies Inc., Reno, NV (United States); Drakos, Peter [Ormat Technologies Inc., Reno, NV (United States); Spielman, Paul [Ormat Technologies Inc., Reno, NV (United States); Akerley, John [Ormat Technologies Inc., Reno, NV (United States)

    2013-09-30

    This manuscript is a draft to replaced with a final version at a later date TBD. A summary of activities pertaining to the Desert Peak EGS project including the planning and resulting stimulation activities.

  3. Population dynamics of caribou herds in southwestern Alaska

    Directory of Open Access Journals (Sweden)

    Patrick Valkenburg

    2003-04-01

    Full Text Available The five naturally occurring and one transplanted caribou (Rangifer tarandus granti herd in southwestern Alaska composed about 20% of Alaska's caribou population in 2001. All five of the naturally occurring herds fluctuated considerably in size between the late 1800s and 2001 and for some herds the data provide an indication of long-term periodic (40-50 year fluctuations. At the present time, the Unimak (UCH and Southern Alaska Peninsula (SAP are recovering from population declines, the Northern Alaska Peninsula Herd (NAP appears to be nearing the end of a protracted decline, and the Mulchatna Herd (MCH appears to now be declining after 20 years of rapid growth. The remaining naturally occurring herd (Kilbuck has virtually disappeared. Nutrition had a significant effect on the size of 4-month-old and 10-month-old calves in the NAP and the Nushagak Peninsula Herd (NPCH and probably also on population growth in at least 4 (SAP, NAP, NPCH, and MCH of the six caribou herds in southwestern Alaska. Predation does not appear to be sufficient to keep caribou herds in southwestern Alaska from expanding, probably because rabies is endemic in red foxes (Vulpes vulpes and is periodically transferred to wolves (Canis lupus and other canids. However, we found evidence that pneumonia and hoof rot may result in significant mortality of caribou in southwestern Alaska, whereas there is no evidence that disease is important in the dynamics of Interior herds. Cooperative conservation programs, such as the Kilbuck Caribou Management Plan, can be successful in restraining traditional harvest and promoting growth in caribou herds. In southwestern Alaska we also found evidence that small caribou herds can be swamped and assimilated by large herds, and fidelity to traditional calving areas can be lost.

  4. Southwestern Power Administration Annual Report 2004-2006

    Energy Technology Data Exchange (ETDEWEB)

    None

    2006-01-01

    Confidence Commitment Cooperation These are words that spring to mind regarding Southwestern Power Administration’s performance during fiscal years (FY) 2004-2006 By offering innovative, customer-oriented service, working to improve system reliability and efficiency, and partnering with customers and other Federal power stakeholders, Southwestern has certainly exhibited all three of these qualities during these challenging yet productive years In fact, our cooperative working relationships were critical to our success during the severe and widespread drought conditions which prevailed throughout Southwestern’s marketing area for much of 2005-2006 When we proposed a temporary energy deferral program, our customers came on board by voluntarily taking less Federal hydropower than they were entitled to, enabling us to preserve system storage and fulfill our contract obligations during the crucial summer months of 2006 The U S Army Corps of Engineers (Corps) also helped improve our drought situation by allowing Southwestern more operational flexibility on a regional level Despite the challenges this critical drought period presented, Southwestern remained committed to fulfilling our mission and strategic goals From FY 2004 through FY 2006, we marketed and delivered all available Federal hydropower while meeting and even exceeding the reliability standards of the North American Electric Reliability Corporation (NERC) Our Power Operations Training Center in Springfield, Missouri, was cited as an “Example of Excellence” during a NERC readiness audit in October 2006; and as we have every year since NERC began measuring, Southwestern far exceeded the accepted NERC compliance ratings for power system operations reliability Our commitment to excellence and accountability has kept our repayment goals on target as well Revenues were sufficient to repay all annual expenses and the required principal investment in the Federal hydropower facilities Furthermore, the original

  5. The greening of the McGill Paleoclimate Model. Part II: Simulation of Holocene millennial-scale natural climate changes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi; Mysak, Lawrence A.; Wang, Zhaomin [McGill University, Department of Atmospheric and Oceanic Sciences and Global Environmental and Climate Change Centre (GEC3), Montreal, Quebec (Canada); Brovkin, Victor [Potsdam Institute for Climate Impact Research (PIK), 601203, Potsdam (Germany)

    2005-04-01

    Various proxy data reveal that in many regions of the Northern Hemisphere (NH), the middle Holocene (6 kyr BP) was warmer than the early Holocene (8 kyr BP) as well as the later Holocene, up to the end of the pre-industrial period (1800 AD). This pattern of warming and then cooling in the NH represents the response of the climate system to changes in orbital forcing, vegetation cover and the Laurentide Ice Sheet (LIS) during the Holocene. In an attempt to better understand these changes in the climate system, the McGill Paleoclimate Model (MPM) has been coupled to the dynamic global vegetation model known as VECODE (see Part I of this two-part paper), and a number of sensitivity experiments have been performed with the ''green'' MPM. The model results illustrate the following: (1) the orbital forcing together with the vegetation - albedo feedback result in the gradual cooling of global SAT from about 6 kyr BP to the end of the pre-industrial period; (2) the disappearance of the LIS over the period 8-6 kyr BP, associated with vegetation - albedo feedback, allows the global SAT to increase and reach its maximum at around 6 kyr BP; (3) the northern limit of the boreal forest moves northward during the period 8-6.4 kyr BP due to the LIS retreat; (4) during the period 6.4-0 kyr BP, the northern limit of the boreal forest moves southward about 120 km in response to the decreasing summer insolation in the NH; and (5) the desertification of northern Africa during the period 8-2.6 kyr BP is mainly explained by the decreasing summer monsoon precipitation. (orig.)

  6. Impacts of Mega-droughts on Water and Food Security in the Indo-Gangetic Plains: A Paleoclimate Scenario Analysis

    Science.gov (United States)

    Zhu, T.; Pitois, G.; Ringler, C.; Wang, D.; Rosegrant, M. W.

    2014-12-01

    Spanning over Pakistan, northern India, Nepal, and Bangladesh, the Indo-Gangetic Plains (IGP) is the home of several hundred million people and the "bread basket" for much of South Asia. The flat terrain, fertile soils, and favorable climate of the IGP make it agriculturally productive. However prolonged droughts caused by consecutive monsoon failures can seriously affect crop production and social wellbeing, in particular for the eastern part of the plains where agriculture remains largely rain-fed. Severe droughts were observed in the IGP historically, and recent paleoclimate studies reveal that more severe and long-lasting "mega-droughts" had happened in the distant past. Agricultural losses from major droughts can dramatically affect food systems and increase the vulnerability of resource-poor people given the delicate balance between food supply and demand under growing natural resource scarcity. To estimate the potential impacts of "mega-droughts" on the water and food systems in the IGP, we develop worst-case drought scenarios through inverse modeling of tree-ring-based PDSI reconstruction that covers the period 1300-1899 (A.D.), and analyze these historic mega-drought scenarios using IFPRI's IMPACT global water and food projections model. The base year of the IMPACT model is parameterized using socioeconomic and engineering data that reflect today's water management and infrastructure, agricultural technologies, population, income, and market institutions. The base year simulation is validated against observations to ensure model fidelity. Anticipated changes of the above factors in the future out to 2050 are specified using demographic and economic growth projections and literature data. Model simulation results represent the consequences of mega-droughts in the IGP given technological and socioeconomic conditions of today and in the future. We also explore policy options for increasing the resilience of water and food systems in the IGP, through scenario

  7. High-resolution paleoclimate records of Holocene hydroclimatic variability in the Eastern Colombian Andes from Lago de Tota

    Science.gov (United States)

    Ahmed, M. N.; Bird, B. W.; Escobar, J.; Polissar, P. J.

    2017-12-01

    The Northern Hemisphere (NH) South American Monsoon (SAM) is a significant source of precipitation for the North Andes (north of 0˚) and has major control over regional hydroclimate variability. Holocene-length histories of NH SAM variability are few compared to the Southern Hemisphere (SH), limiting understanding of how these systems are connected on orbital and shorter timescales. Here, we present multi-proxy lake-sediment-based paleoclimate and paleohydrologic reconstructions from Lago de Tota, Colombia, using sedimentological, geochemical and leaf-wax hydrogen isotopic indicators from radiometically dated cores. The results indicate periods of wet and dry climate phases during the past 9000 BP with an average Holocene sedimentation rate 33cm/kyr. An increase in total organic matter (TOM) content and finer grain-size distributions was observed from 8000 to 3200 BP, suggesting a period of high lake level. This was followed by lower TOM and coarser grain sizes, suggesting lower lake levels from 3200 BP to the present. Although Tota's lake level pattern is antiphased with other lake level reconstructions from the NH and SH Andes, it is consistent with hypothesized changes in atmospheric convection over the Andes during the Holocene and the way in which they would be modified by the so-called dry island effect in the Colombian Andes. This suggests that a common forcing mechanism can be invoked to explain differing millennial-scale Andean hydroclimate changes, namely atmospheric convection. Orbital and Pacific atmosphere-forcing are therefore likely to have played a significant role in driving pan-Andean hydroclimate variability based on their inter-hemispheric influence on Andean convection.

  8. Fire, Ice and Water: Glaciologic, Paleoclimate and Anthropogenic Linkages During Past Mega-Droughts in the Uinta Mountains, Utah

    Science.gov (United States)

    Power, M. J.; Rupper, S.; Codding, B.; Schaefer, J.; Hess, M.

    2017-12-01

    Alpine glaciers provide a valuable water source during prolonged drought events. We explore whether long-term climate dynamics and associated glacier changes within mountain drainage basins and adjacent landscapes ultimately influence how prehistoric human populations choose settlement locations. The Uinta Mountains of Utah, with a steep present-day precipitation gradient from the lowlands to the alpine zone of 20-100 cm per year, has a rich glacial history related to natural and anthropogenic climate variability. Here we examine how past climate variability has impacted glaciers and ultimately the availability of water over long timescales, and how these changes affected human settlement and subsistence decisions. Through a combination of geomorphologic evidence, paleoclimate proxies, and glacier and climate modelling, we test the hypothesis that glacier-charged hydrologic systems buffer prehistoric populations during extreme drought periods, facilitating long-term landscape management with fire. Initial field surveys suggest middle- and low-elevation glacial valleys contain glacially-derived sediment from meltwater and resulted in terraced river channels and outwash plains visible today. These terraces provide estimates of river discharge during varying stages of glacier advance and retreat. Archaeological evidence from middle- and high-elevations in the Uinta Mountains suggests human populations persisted through periods of dramatic climate change, possibly linked to the persistence of glacially-derived water resources through drought periods. Paleoenvironmental records indicate a long history of fire driven by the combined interaction of climatic variation and human disturbance. This research highlights the important role of moisture variability determining human settlement patterns and landscape management throughout time, and has direct relevance to the impacts of anthropogenic precipitation and glacier changes on vulnerable populations in the coming century

  9. An isotopic and modelling study of flow paths and storage in Quaternary calcarenite, SW Australia: implications for speleothem paleoclimate records

    Science.gov (United States)

    Treble, Pauline C.; Bradley, Chris; Wood, Anne; Baker, Andy; Jex, Catherine N.; Fairchild, Ian J.; Gagan, Michael K.; Cowley, Joan; Azcurra, Cecilia

    2013-03-01

    We investigated the distinctive shallow sub-surface hydrology of the southwest Western Australia (SWWA) dune calcarenite using observed rainfall and rainfall δ18O; soil moisture, cave drip rate and dripwater δ18O over a six-year period: August 2005-March 2012. A lumped parameter hydrological model is developed to describe water fluxes and drip δ18O. Comparison of observed data and model output allow us to assess the critical non-climatic karst hydrological processes that modify the precipitation δ18O signal and discuss the implications for speleothem paleoclimate records from this cave and those with a similar karst setting. Our findings include evidence of multiple reservoirs, characterised by distinct δ18O values and recharge responses ('low' and 'high' flow sites). Dripwaters exhibit δ18O variations in wet versus dry years at low-flow sites receiving diffuse seepage from the epikarst with an attenuated isotopic composition that approximates mean rainfall. Recharge from high-magnitude rain events is stored in a secondary reservoir which is associated with high-flow dripwater that is 1‰ lower than our monitored low-flow sites (δ18O). One drip site is characterised by mixed-flow behaviour and exhibits a non-linear threshold response after the cessation of drainage from a secondary reservoir following a record dry year (2006). Additionally, our results yield a better understanding of the vadose zone hydrology and dripwater characteristics in Quaternary age dune limestones. We show that flow to our monitored sites is dominated by diffuse flow with inferred transit times of less than one year. Diffuse flow appears to follow vertical preferential paths through the limestone reflecting differences in permeability and deep recharge into the host rock.

  10. Aerosol radiative forcing during African desert dust events (2005–2010 over Southeastern Spain

    Directory of Open Access Journals (Sweden)

    A. Valenzuela

    2012-11-01

    Full Text Available The daily (24 h averages of the aerosol radiative forcing (ARF at the surface and the top of the atmosphere (TOA were calculated during desert dust events over Granada (southeastern Spain from 2005 to 2010. A radiative transfer model (SBDART was utilized to simulate the solar irradiance values (0.31–2.8 μm at the surface and TOA, using as input aerosol properties retrieved from CIMEL sun photometer measurements via an inversion methodology that uses the sky radiance measurements in principal plane configuration and a spheroid particle shape approximation. This inversion methodology was checked by means of simulated data from aerosol models, and the derived aerosol properties were satisfactorily compared against well-known AERONET products. Good agreement was found over a common spectral interval (0.2–4.0 μm between the simulated SBDART global irradiances at surface and those provided by AERONET. In addition, simulated SBDART solar global irradiances at the surface have been successfully validated against CM-11 pyranometer measurements. The comparison indicates that the radiative transfer model slightly overestimates (mean bias of 3% the experimental solar global irradiance. These results show that the aerosol optical properties used to estimate ARF represent appropriately the aerosol properties observed during desert dust outbreak over the study area. The ARF mean monthly values computed during desert dust events ranged from −13 ± 8 W m−2 to −34 ± 15 W m−2 at surface, from −4 ± 3 W m−2 to −13 ± 7 W m−2 at TOA and from +6 ± 4 to +21 ± 12 W m−2 in the atmosphere. We have checked if the differences found in aerosol optical properties among desert dust sectors translate to differences in ARF. The mean ARF at surface (TOA were −20 ± 12 (−5 ± 5 W m−2, −21 ± 9 (−7 ± 5 W m−2 and −18 ± 9 (−6 ± 5 W m−2 for sector A

  11. Water appropriation and ecosystem stewardship in the Baja desert

    OpenAIRE

    de las Heras Alejandro; Rodriguez Mario A.; Islas-Espinoza Marina

    2014-01-01

    The UNESCO San Francisco Rock Paintings polygon within El Vizcaino Biosphere Reserve in the Baja California Peninsula derives its moisture from the North American monsoon. There, ranchers have depended on the desert since the 18th century. More recently, the desert has depended on the environmental stewardship of the ranchers who have allayed mining exploitation and archaeological looting. Using a Rapid Assessment Procedure (RAP), climate data, and geographical informa...

  12. MX Siting Investigation. Gravity Survey - Sevier Desert Valley, Utah.

    Science.gov (United States)

    1981-01-24

    Cheyenne, Wyoming. DMAHTC reduces the data to Simple Bouguer Anomaly (see Section A1.4, Appendix Al.0). The Defense Mapping Agency Aerospace Center...Desert Valley, Utah ......... 2 2 Topographic Setting - Sevier Desert Valley, Utah . 3 LIST OF DRAWINGS Drawing Number 1 Complete Bouguer Anomaly...gravity stations were distributed throughout the valley at an approxi- mate interval of 1.4 miles (2.3 km). Drawing 1 is a Complete Bouguer Anomaly

  13. Stable Isotopic Analysis on Water Utilization of Two Xerophytic Shrubs in a Revegetated Desert Area: Tengger Desert, China

    OpenAIRE

    Lei Huang; Zhishan Zhang

    2015-01-01

    Stable isotope studies on stable isotope ratios of hydrogen and oxygen in water within plants provide new information on water sources and water use patterns under natural conditions. In this study, the sources of water uptake for two typical xerophytic shrubs, Caragana korshinskii and Artemisia ordosica, were determined at four different-aged revegetated sites (1956, 1964, 1981, and 1987) in the Tengger Desert, a revegetated desert area in China. Samples from precipitation, soil water at dif...

  14. Petrography and stable isotope geochemistry of Oligocene-Miocene continental carbonates in south Texas: Implications for paleoclimate and paleoenvironment near sea-level

    Science.gov (United States)

    Godfrey, Conan; Fan, Majie; Jesmok, Greg; Upadhyay, Deepshikha; Tripati, Aradhna

    2018-05-01

    Cenozoic sedimentary rocks in the southern Texas Gulf Coastal Plains contain abundant continental carbonates that are useful for reconstructing terrestrial paleoclimate and paleoenvironment in a region near sea-level. Our field observations and thin section characterizations of the Oligocene and Miocene continental carbonates in south Texas identified three types of pedogenic carbonates, including rhizoliths, carbonate nodules, and platy horizons, and two types of groundwater carbonates, including carbonate-cemented beds and carbonate concretions, with distinctive macromorphologic and micromorphologic features. Based on preservations of authigenic microfabrics and variations of carbon and oxygen isotopic compositions, we suggest these carbonates experienced minimal diagenesis, and their stable isotopic compositions reflect paleoclimate and paleoenvironment in south Texas. Our Oligocene and Miocene carbonate clumped isotope temperatures (T(Δ47)) are 23-28 °C, slightly less than or comparable to the range of modern mean annual and mean warm season air temperature (21-27 °C) in the study area. These T(Δ47) values do not show any dependency on carbonate-type, or trends through time suggesting that groundwater carbonates were formed at shallow depths. These data could indicate that air temperature in south Texas was relatively stable since the early Oligocene. The reconstructed paleo-surface water δ18O values are similar to modern surface water which could indicate that meteoric water δ18O values also remained stable since the early Oligocene. Mean pedogenic carbonate δ13C values increased - 4.6‰ during the late Miocene, most likely reflecting an expansion of C4 grassland in south Texas. This study provides the first mid- and late Cenozoic continental records of paleoclimate and paleoecology in a low-latitude, near sea-level region.

  15. The Power of Cooperation in International Paleoclimate Science: Examples from the PAGES 2k Network and the Ocean2k Working Group

    Science.gov (United States)

    Addison, J. A.

    2015-12-01

    The Past Global Changes (PAGES) project of IGBP and Future Earth supports research to understand the Earth's past environment to improve future climate predictions and inform strategies for sustainability. Within this framework, the PAGES 2k Network was established to provide a focus on the past 2000 years, a period that encompasses Medieval Climate Anomaly warming, Little Ice Age cooling, and recent anthropogenically-forced climate change. The results of these studies are used for testing earth system models, and for understanding decadal- to centennial-scale variability, which is needed for long-term planning. International coordination and cooperation among the nine regional Working Groups that make up the 2k Network has been critical to the success of PAGES 2k. The collaborative approach is moving toward scientific achievements across the regional groups, including: (i) the development of a community-driven open-access proxy climate database; (ii) integration of multi-resolution proxy records; (iii) development of multivariate climate reconstructions; and (iv) a leap forward in the spatial resolution of paleoclimate reconstructions. The last addition to the 2k Network, the Ocean2k Working Group has further innovated the collaborative approach by: (1) creating an open, receptive environment to discuss ideas exclusively in the virtual space; (2) employing an array of real-time collaborative software tools to enable communication, group document writing, and data analysis; (3) consolidating executive leadership teams to oversee project development and manage grassroots-style volunteer pools; and (4) embracing the value-added role that international and interdisciplinary science can play in advancing paleoclimate hypotheses critical to understanding future change. Ongoing efforts for the PAGES 2k Network are focused on developing new standards for data quality control and archiving. These tasks will provide the foundation for new and continuing "trans-regional" 2k

  16. Respondence and feedback of modern sand deserts to climate change--A case study in Gurbantunggut Desert

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The research on the respondence and feedback of modern sand deserts to the climate change is an important component part in the studies on the global climate change. Deserts respond to the climate change, meanwhile, they affect the climate with their feedback of peculiar environment during the respondence. Many researches on desert climate have been carried out at home and abroad. However, there is little research on the respondence and feedback of modern fixed, semi-fixed and mobile deserts in arid areas to the climate change, in which the factor analysis as well as the parameter changing effects is especially the difficult problem all along. In this note, the parameters of the respondence and feedback of Gurbantunggut Desert to the climate change are measured and analyzed, some variable parameters of water-heat exchange are obtained, and a numerical model of desertification is developed according to a series of climate change of about 40 years and the variable relations of meteorological and physical features of the sand surface in Gurbantunggut Desert.

  17. From Fireproof Desert to Flammable Grassland: Buffelgrass Invasion in the Sonoran Desert

    Science.gov (United States)

    Betancourt, J. L.

    2007-12-01

    Only a few decades ago, the Sonoran Desert of northwestern Mexico and southern Arizona was considered mostly fireproof, a case of not enough fine fuel to connect the dominant shrubs and cacti. This has changed with invasions by non-native, winter annual and summer-flower perennial grasses that are rapidly transforming fireproof desert into flammable grassland. Of particular concern is buffelgrass, Pennisetum ciliare, a fire-prone and invasive African perennial grass that has already converted millions of hectares across Sonora since the mid-1960s and has made quick headway in southern and central Arizona beginning in the 1980s. Near Tucson and Phoenix, AZ, buffelgrass invasion is proceeding exponentially, with population expansion (and the costs of mitigation) more than doubling every year. As this conversion progresses, there will be increased fire risks, lost tourist revenue, diminished property values, insurmountable setbacks to conservation efforts, and the threat of large ignition fronts in desert valleys routinely spreading into the mountains. Although somewhat belated, an integrated, multi-jurisdictional effort is being organized to reduce ecological and economic impacts. My presentation will summarize the history and context of buffelgrass introduction and invasion, the disconnect in attitudes and policies across state and international boundaries, ongoing management efforts, the role of science and responsibilities of scientists, accelerated spread with changing climate, and impacts to regional ecosystems and economies. This narrative may serve as a template for other semi-arid lands where buffelgrass and similar grasses have become invasive, including Australia, South America, and many islands in the Pacific Ocean (including Hawaii), Indian Ocean, and Caribbean Sea.

  18. Southwestern Power Administration Combined Financial Statements, 2006-2009

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-09-01

    We have audited the accompanying combined balance sheets of the Southwestern Federal Power System (SWFPS), as of September 30, 2009, 2008, 2007, and 2006, and the related combined statements of revenues and expenses, changes in capitalization, and cash flows for the years then ended. As described in note 1(a), the combined financial statement presentation includes the hydroelectric generation functions of another Federal agency (hereinafter referred to as the generating agency), for which Southwestern Power Administration (Southwestern) markets and transmits power. These combined financial statements are the responsibility of the management of Southwestern and the generating agency. Our responsibility is to express an opinion on these combined financial statements based on our audits. We conducted our audits in accordance with auditing standards generally accepted in the United States of America. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the combined financial statements are free of material misstatement. An audit includes consideration of internal control over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of Southwestern and the generating agency’s internal control over financial reporting. Accordingly, we express no such opinion. An audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the combined financial statements, assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall combined financial statement presentation. We believe that our audits provide a reasonable basis for our opinion. In our opinion, the combined financial statements referred to above present fairly, in all material respects, the respective financial position of the Southwestern Federal Power

  19. Enhancing and restoring habitat for the desert tortoise

    Science.gov (United States)

    Abella, Scott R.; Berry, Kristin H.

    2016-01-01

    Habitat has changed unfavorably during the past 150 y for the desert tortoise Gopherus agassizii, a federally threatened species with declining populations in the Mojave Desert and western Sonoran Desert. To support recovery efforts, we synthesized published information on relationships of desert tortoises with three habitat features (cover sites, forage, and soil) and candidate management practices for improving these features for tortoises. In addition to their role in soil health and facilitating recruitment of annual forage plants, shrubs are used by desert tortoises for cover and as sites for burrows. Outplanting greenhouse-grown seedlings, protected from herbivory, has successfully restored (>50% survival) a variety of shrubs on disturbed desert soils. Additionally, salvaging and reapplying topsoil using effective techniques is among the more ecologically beneficial ways to initiate plant recovery after severe disturbance. Through differences in biochemical composition and digestibility, some plant species provide better-quality forage than others. Desert tortoises selectively forage on particular annual and herbaceous perennial species (e.g., legumes), and forage selection shifts during the year as different plants grow or mature. Nonnative grasses provide low-quality forage and contribute fuel to spreading wildfires, which damage or kill shrubs that tortoises use for cover. Maintaining a diverse “menu” of native annual forbs and decreasing nonnative grasses are priorities for restoring most desert tortoise habitats. Reducing herbivory by nonnative animals, carefully timing herbicide applications, and strategically augmenting annual forage plants via seeding show promise for improving tortoise forage quality. Roads, another disturbance, negatively affect habitat in numerous ways (e.g., compacting soil, altering hydrology). Techniques such as recontouring road berms to reestablish drainage patterns, vertical mulching (“planting” dead plant material

  20. Diversity and feeding strategies of soil microfauna along elevation gradients in Himalayan cold deserts.

    Directory of Open Access Journals (Sweden)

    Miloslav Devetter

    Full Text Available High-elevation cold deserts in Tibet and Himalaya are one of the most extreme environments. One consequence is that the diversity of macrofauna in this environment is often limited, and soil microorganisms have a more influential role in governing key surface and subsurface bioprocesses. High-elevation soil microfauna represent important components of cold ecosystems and dominant consumers of microbial communities. Still little is known about their diversity and distribution on the edge of their reproductive and metabolic abilities. In this study, we disentangle the impact of elevation and soil chemistry on diversity and distribution of rotifers, nematodes and tardigrades and their most frequent feeding strategies (microbial filter-feeders, bacterivores, fungivores, root-fungal feeders, omnivores along two contrasting altitudinal gradients in Indian NW Himalaya (Zanskar transect from 3805 to 4714 m a.s.l. and southwestern Tibet (Tso Moriri transect from 4477 to 6176 m a.s.l., using a combination of multivariate analysis, variation partitioning and generalized additive models. Zanskar transect had higher precipitation, soil moisture, organic matter and available nutrients than dry Tso Moriri transect. In total, 40 species of nematodes, 19 rotifers and 1 tardigrade were discovered. Species richness and total abundance of rotifers and nematodes showed mid-elevation peaks in both investigated transects. The optimum for rotifers was found at higher elevation than for nematodes. Diversity and distribution of soil microfauna was best explained by soil nitrogen, phosphorus and organic matter. More fertile soils hosted more diverse and abundant faunal communities. In Tso Moriri, bacterivores represented 60% of all nematodes, fungivores 35%, root-fungal feeders 1% and omnivores 3%. For Zanskar the respective proportions were 21%, 13%, 56% and 9%. Elevational optima of different feeding strategies occurred in Zanskar in one elevation zone (4400-4500 m

  1. Structure, agency, and the transformation of the Sonoran Desert by buffelgrass (Pennisetum ciliare): An application of land change science

    Science.gov (United States)

    Brenner, Jacob C.

    A regional land transformation is underway in the Sonoran Desert of southwestern North America as a result of the conversion of native rangeland to exotic pasture. In northwestern Sonora, Mexico the process involves clearing native vegetation for cultivation of buffelgrass (Pennisetum ciliare). Southern African buffelgrass was introduced to Sonora through the United States in the 1950s with generous support from the Mexican federal and Sonoran state governments. The ascendance of buffelgrass as a range management tool in Sonora has been conditioned by an international political economy of beef production. However, land use decisions regarding buffelgrass are also conditioned by factors internal to the ranch household. This research examines the expansion of buffelgrass in the Sonoran Desert, addressing its extent and drivers. Through the use of systematic interviews with ranchers, key informant interviews with government officials, and an examination of northern Mexico's cattle ranching history and policy, the dissertation documents why buffelgrass has spread as a policy program and management choice. This part of the work addresses a "structure-agency debate" in human-environment geography. Next the research turns to landscape impacts of buffelgrass cultivation, through vegetation plot and transect sampling. The extent, cover, and density of buffelgrass inside and outside fenced pastures are examined, confirming the hypothesis that disturbance facilitates invasion from pastures onto surrounding lands. Finally, the research employs novel methods of remote sensing and geographic information science using a 1973-2006 time series of Landsat imagery to characterize the patterns and temporal trajectories of land change by buffelgrass across the site. Object-based image processing techniques are combined with traditional maximum likelihood techniques and classification tree analysis to address the difficult task of distinguishing buffelgrass from other prevalent land

  2. Closed bioregenerative life support systems: Applicability to hot deserts

    Science.gov (United States)

    Polyakov, Yuriy S.; Musaev, Ibrahim; Polyakov, Sergey V.

    2010-09-01

    Water scarcity in hot deserts, which cover about one-fifth of the Earth's land area, along with rapid expansion of hot deserts into arable lands is one of the key global environmental problems. As hot deserts are extreme habitats characterized by the availability of solar energy with a nearly complete absence of organic life and water, space technology achievements in designing closed ecological systems may be applicable to the design of sustainable settlements in the deserts. This review discusses the key space technology findings for closed biogenerative life support systems (CBLSS), which can simultaneously produce food, water, nutrients, fertilizers, process wastes, and revitalize air, that can be applied to hot deserts. Among them are the closed cycle of water and the acceleration of the cycling times of carbon, biogenic compounds, and nutrients by adjusting the levels of light intensity, temperature, carbon dioxide, and air velocity over plant canopies. Enhanced growth of algae and duckweed at higher levels of carbon dioxide and light intensity can be important to provide complete water recycling and augment biomass production. The production of fertilizers and nutrients can be enhanced by applying the subsurface flow wetland technology and hyper-thermophilic aerobic bacteria for treating liquid and solid wastes. The mathematical models, optimization techniques, and non-invasive measuring techniques developed for CBLSS make it possible to monitor and optimize the performance of such closed ecological systems. The results of long-duration experiments performed in BIOS-3, Biosphere 2, Laboratory Biosphere, and other ground-based closed test facilities suggest that closed water cycle can be achieved in hot-desert bioregenerative systems using the pathways of evapotranspiration, condensation, and biological wastewater treatment technologies. We suggest that the state of the art in the CBLSS design along with the possibility of using direct sunlight for

  3. Copper isotope fractionation by desert shrubs

    International Nuclear Information System (INIS)

    Navarrete, Jesica U.; Viveros, Marian; Ellzey, Joanne T.; Borrok, David M.

    2011-01-01

    Copper has two naturally occurring stable isotopes of masses 63 and 65 which can undergo mass dependent fractionation during various biotic and abiotic chemical reactions. These interactions and their resulting Cu isotope fractionations can be used to determine the mechanisms involved in the cycling of Cu in natural systems. In this study, Cu isotope changes were investigated at the organismal level in the metal-accumulating desert plant, Prosopis pubescens. Initial results suggest that the lighter Cu isotope was preferentially incorporated into the leaves of the plant, which may suggest that Cu was actively transported via intracellular proteins. The roots and stems show a smaller degree of Cu isotope fractionation and the direction and magnitude of the fractionations was dependent upon the levels of Cu exposure. Based on this and previous work with bacteria and yeast, a trend is emerging that suggests the lighter Cu isotope is preferentially incorporated into biological components, while the heavier Cu isotope tends to become enriched in aqueous solutions. In bacteria, plants and animals, intracellular Cu concentrations are strictly regulated via dozens of enzymes that can bind, transport, and store Cu. Many of these enzymes reduce Cu(II) to Cu(I). These initial results seem to fit into a broader picture of Cu isotope cycling in natural systems where oxidation/reduction reactions are fundamental in controlling the distributions of Cu isotopes.

  4. Status of the Desert Fireball Network

    Science.gov (United States)

    Devillepoix, H. A. R.; Bland, P. A.; Towner, M. C.; Cupák, M.; Sansom, E. K.; Jansen-Sturgeon, T.; Howie, R. M.; Paxman, J.; Hartig, B. A. D.

    2016-01-01

    A meteorite fall precisely observed from multiple locations allows us to track the object back to the region of the Solar System it came from, and sometimes link it with a parent body, providing context information that helps trace the history of the Solar System. The Desert Fireball Network (DFN) is built in arid areas of Australia: its observatories get favorable observing conditions, and meteorite recovery is eased thanks to the mostly featureless terrain. After the successful recovery of two meteorites with 4 film cameras, the DFN has now switched to a digital network, operating 51 cameras, covering 2.5 million km2 of double station triangulable area. Mostly made of off-the-shelf components, the new observatories are cost effective while maintaining high imaging performance. To process the data (~70TB/month), a significant effort has been put to writing an automated reduction pipeline so that all events are reduced with little human intervention. Innovative techniques have been implemented for this purpose: machine learning algorithms for event detection, blind astrometric calibration, and particle filter simulations to estimate both physical properties and state vector of the meteoroid. On 31 December 2015, the first meteorite from the digital systems was recovered: Murrili (the 1.68 kg H5 ordinary chondrite was observed to fall on 27 November 2015). Another 11 events have been flagged as potential meteorites droppers, and are to be searched in the coming months.

  5. Greetings and Politeness in Doctor-Client Encounters in Southwestern

    Directory of Open Access Journals (Sweden)

    Akin Odebunmi

    2013-05-01

    Full Text Available Doctors and clients sometimes experience interactiveclashes during hospital meetings in South-western Nigerianhospitals because of their divergent culture-constrainedorientation to politeness cues. The goal of this paper is tounpack the discursive elements that characterize interactiveconfluence and divergence in selected consultativeencounters in the hospitals. The findings indicate thatinstitutional and cultural (disalignments occur in respect ofadjacency and non-adjacency pair greetings. In bothgreeting types, face support, threat and stasis are conjointlyco-constituted by doctors and Yoruba clients within theaffordances of the cultural, institutional and situationalcontext of the Southwestern Nigerian hospital setting.Adjacency pair greetings attract mutual interpretingsbetween the parties; interactive disalignments aredifferentially pragmatically accommodated by doctors andclients. In non-adjacency pair greeting, doctors’ threats areco-constituted as appropriate by both parties, theinstitutional power of doctor and shared Western culturalorientation playing significant roles.

  6. Paleoclimate Records from New Zealand Maar Lakes, Insights into ENSO Teleconnections and Climatic Events in the South (West) Pacific.

    Science.gov (United States)

    Shulmeister, J.; Nobes, D. C.; Striewski, B.

    2008-05-01

    The maar craters of the New Zealand Auckland Volcanic Field (36.5°S, 174.5°E) contain some of the highest resolution late-Quaternary paleoclimate records in the Southern Hemisphere. Here we integrate laminae count results from recent drilling in the Hopua Crater with existing records from the nearby Onepoto Crater (Pepper et al., 2004). In total these records cover many thousands of years between the onset of the last glaciation maximum and the early mid-Holocene. The cores are strongly laminated. Individual laminae in both craters are very fine (sub-mm to mm scale) and form couplets which comprise a darker mineralogenic rich layer and a lighter diatomaceous layer. In places these couplets are annual, and may reflect seasonal algal blooms, but in other sections of the record, notably through the late-Glacial and Holocene, the couplets are deposited at inter-annual time scales. Spectral analyses of couplet thickness counts using a fast Fourier transform (FFT) with 64 to 256-year running windows, and a 50 per cent overlap indicate strong spectral power during the LGM and markedly weaker power during both the deglaciation and early Holocene. In fact there is no spectral strength for most of these periods. Three brief (centennial duration) events punctuate this extended period of low spectral power. These occur at c. 16 ka, c. 14.8 ka and during the early Holocene. They display spectral power in the 5-7yr ENSO window and also at longer time intervals that may be consistent with the Pacific Decadal Oscillation. We infer the local switching on (or up) of ENSO and PDO teleconnections and suspect these are embedded in circum-polar circulation changes. In addition to these spectral power episodes, there is a general increase in the number of couplet cycles per century between the deglaciation and the early mid-Holocene. This matches observations from Equador and Peru and suggests that trans-Pacific ENSO responses are in phase between western tropical South America and New

  7. Paleoclimate in continental northwestern Europe during the Eemian and early Weichselian (125-97 ka): insights from a Belgian speleothem

    Science.gov (United States)

    Vansteenberge, Stef; Verheyden, Sophie; Cheng, Hai; Edwards, R. Lawrence; Keppens, Eddy; Claeys, Philippe

    2016-07-01

    The last interglacial serves as an excellent time interval for studying climate dynamics during past warm periods. Speleothems have been successfully used for reconstructing the paleoclimate of last interglacial continental Europe. However, all previously investigated speleothems are restricted to southern Europe or the Alps, leaving large parts of northwestern Europe undocumented. To better understand regional climate changes over the past, a larger spatial coverage of European last interglacial continental records is essential, and speleothems, because of their ability to obtain excellent chronologies, can provide a major contribution. Here, we present new, high-resolution data from a stalagmite (Han-9) obtained from the Han-sur-Lesse Cave in Belgium. Han-9 formed between 125.3 and ˜ 97 ka, with interruptions of growth occurring at 117.3-112.9 and 106.6-103.6 ka. The speleothem was investigated for its growth, morphology and stable isotope (δ13C and δ18O) composition. The speleothem started growing relatively late within the last interglacial, at 125.3 ka, as other European continental archives suggest that Eemian optimum conditions were already present during that time. It appears that the initiation of Han-9 growth is caused by an increase in moisture availability, linked to wetter conditions around 125.3 ka. The δ13C and δ18O proxies indicate a period of relatively stable conditions after 125.3 ka; however, at 120 ka the speleothem δ18O registered the first signs of regionally changing climate conditions, being a modification of ocean source δ18O linked to an increase in ice volume towards the Marine Isotope Stage (MIS) 5e-5d transition. At 117.5 ka, drastic vegetation changes are recorded by Han-9 δ13C immediately followed by a cessation of speleothem growth at 117.3 ka, suggesting a transition to significantly dryer conditions. The Han-9 record covering the early Weichselian displays larger amplitudes in both isotope proxies and changes in stalagmite

  8. Entomologic Inoculation Rates of Anopheles arabiensis in Southwestern Ethiopia

    OpenAIRE

    Ulesido, Fekadu Massebo; Balkew, Meshesha; Gebre-Michael, Teshome; Lindtjørn, Bernt

    2013-01-01

    We collected anophelines every second week for one year from randomly selected houses in southwestern Ethiopia by using Centers for Disease Control (CDC) light traps, pyrethrum spray catches, and artificial pit shelter constructions to detect circumsporozoite proteins and estimate entomologic inoculation rates (EIRs). Of 3,678 Anopheles arabiensis tested for circumsporozoite proteins, 11 were positive for Plasmodium falciparum and three for P. vivax. The estimated annual P. falciparum EIR of ...

  9. Water Sources for Cyanobacteria Below Desert Rocks in the Negev Desert Determined by Conductivity

    Science.gov (United States)

    McKay, Christopher P.

    2016-01-01

    We present year round meteorological and conductivity measurements of colonized hypolithic rocks in the Arava Valley, Negev Desert, Israel. The data indicate that while dew is common in the Negev it is not an important source of moisture for hypolithic organisms at this site. The dominance of cyanobacteria in the hypolithic community are consistent with predictions that cyanobacteria are confined to habitats supplied by rain. To monitor the presence of liquid water under the small Negev rocks we developed and tested a simple field conductivity system based on two wires placed about 0.5 cm apart. Based on 21 replicates recorded for one year in the Negev we conclude that in natural rains (0.25 mm to 6 mm) the variability between sensor readings is between 20 and 60% decreasing with increasing rain amount. We conclude that the simple small electrical conductivity system described here can be used effectively to monitor liquid water levels in lithic habitats. However, the natural variability of these sensors indicates that several replicates should be deployed. The results and method presented have use in arid desert reclamation programs.

  10. Water sources for cyanobacteria below desert rocks in the Negev Desert determined by conductivity

    Directory of Open Access Journals (Sweden)

    Christopher P. McKay

    2016-04-01

    Full Text Available We present year round meteorological and conductivity measurements of colonized hypolithic rocks in the Arava Valley, Negev Desert, Israel. The data indicate that while dew is common in the Negev it is not an important source of moisture for hypolithic organisms at this site. The dominance of cyanobacteria in the hypolithic community is consistent with predictions that cyanobacteria are confined to habitats supplied by rain. To monitor the presence of liquid water under the small Negev rocks we developed and tested a simple field conductivity system based on two wires placed about 0.5 cm apart. Based on 21 replicates recorded for one year in the Negev we conclude that in natural rains (0.25 mm to 6 mm the variability between sensor readings is between 20 and 60% decreasing with increasing rain amount. We conclude that the simple small electrical conductivity system described here can be used effectively to monitor liquid water levels in lithic habitats. However, the natural variability of these sensors indicates that several replicates should be deployed. The results and method presented have use in arid desert reclamation programs.

  11. Genetic variation in the endangered Southwestern Willow Flycatcher

    Science.gov (United States)

    Busch, Joseph; Miller, Mark P.; Paxton, E.H.; Sogge, M.K.; Keim, Paul

    2000-01-01

    The Southwestern Willow Flycatcher (Empidonax traillii extimus) is an endangered Neotropical migrant that breeds in isolated remnants of dense riparian habitat in the southwestern United States. We estimated genetic variation at 20 breeding sites of the Southwestern Willow Flycatcher (290 individuals) using 38 amplified fragment length polymorphisms (AFLPs). Our results suggest that considerable genetic diversity exists within the subspecies and within local breeding sites. Statistical analyses of genetic variation revealed only slight, although significant, differentiation among breeding sites (Mantel's r = 0.0705, P UPGMA cluster analysis of the AFLP markers indicates that extensive gene flow has occurred among breeding sites. No one site stood out as being genetically unique or isolated. Therefore, the small level of genetic structure that we detected may not be biologically significant. Ongoing field studies are consistent with this conclusion. Of the banded birds that were resighted or recaptured in Arizona during the 1996 to 1998 breeding seasons, one-third moved between breeding sites and two-thirds were philopatric. Low differentiation may be the result of historically high rangewide diversity followed by recent geographic isolation of breeding sites, although observational data indicate that gene flow is a current phenomenon. Our data suggest that breeding groups of E. t. extimus act as a metapopulation.

  12. Mapping evaporative water loss in desert passerines reveals an expanding threat of lethal dehydration.

    Science.gov (United States)

    Albright, Thomas P; Mutiibwa, Denis; Gerson, Alexander R; Smith, Eric Krabbe; Talbot, William A; O'Neill, Jacqueline J; McKechnie, Andrew E; Wolf, Blair O

    2017-02-28

    Extreme high environmental temperatures produce a variety of consequences for wildlife, including mass die-offs. Heat waves are increasing in frequency, intensity, and extent, and are projected to increase further under climate change. However, the spatial and temporal dynamics of die-off risk are poorly understood. Here, we examine the effects of heat waves on evaporative water loss (EWL) and survival in five desert passerine birds across the southwestern United States using a combination of physiological data, mechanistically informed models, and hourly geospatial temperature data. We ask how rates of EWL vary with temperature across species; how frequently, over what areas, and how rapidly lethal dehydration occurs; how EWL and die-off risk vary with body mass; and how die-off risk is affected by climate warming. We find that smaller-bodied passerines are subject to higher rates of mass-specific EWL than larger-bodied counterparts and thus encounter potentially lethal conditions much more frequently, over shorter daily intervals, and over larger geographic areas. Warming by 4 °C greatly expands the extent, frequency, and intensity of dehydration risk, and introduces new threats for larger passerine birds, particularly those with limited geographic ranges. Our models reveal that increasing air temperatures and heat wave occurrence will potentially have important impacts on the water balance, daily activity, and geographic distribution of arid-zone birds. Impacts may be exacerbated by chronic effects and interactions with other environmental changes. This work underscores the importance of acute risks of high temperatures, particularly for small-bodied species, and suggests conservation of thermal refugia and water sources.

  13. Borehole environmental tracers for evaluating net infiltration and recharge through desert bedrock

    Science.gov (United States)

    Heilweil, V.M.; Solomon, D.K.; Gardner, P.M.

    2006-01-01

    Permeable bedrock aquifers in arid regions are being increasingly developed as water supplies, yet little is generally known about recharge processes and spatial and temporal variability. Environmental tracers from boreholes were used in this study to investigate net infiltration and recharge to the fractured Navajo Sandstone aquifer. Vadose zone tracer profiles at the Sand Hollow study site in southwestern Utah look similar to those of desert soils at other sites, indicating the predominance of matrix flow. However, recharge rates are generally higher in the Navajo Sandstone than in unconsolidated soils in similar climates because the sandstone matrix allows water movement but not root penetration. Water enters the vadose zone either as direct infiltration of precipitation through exposed sandstone and sandy soils or as focused infiltration of runoff. Net infiltration and recharge exhibit extreme spatial variability. High-recharge borehole sites generally have large amounts of vadose zone tritium, low chloride concentrations, and small vadose zone oxygen-18 evaporative shifts. Annual net-infiltration and recharge rates at different locations range from about 1 to 60 mm as determined using vadose zone tritium, 0 to 15 mm using vadose zone chloride, and 3 to 60 mm using groundwater chloride. Environmental tracers indicate a cyclical net-infiltration and recharge pattern, with higher rates earlier in the Holocene and lower rates during the late Holocene, and a return to higher rates during recent decades associated with anomalously high precipitation during the latter part of the 20th century. The slightly enriched stable isotopic composition of modern groundwater indicates this recent increase in precipitation may be caused by a stronger summer monsoon or winter southern Pacific El Nin??o storm track. ?? Soil Science Society of America.

  14. Stream hierarchy defines riverscape genetics of a North American desert fish.

    Science.gov (United States)

    Hopken, Matthew W; Douglas, Marlis R; Douglas, Michael E

    2013-02-01

    Global climate change is apparent within the Arctic and the south-western deserts of North America, with record drought in the latter reflected within 640,000 km(2) of the Colorado River Basin. To discern the manner by which natural and anthropogenic drivers have compressed Basin-wide fish biodiversity, and to establish a baseline for future climate effects, the Stream Hierarchy Model (SHM) was employed to juxtapose fluvial topography against molecular diversities of 1092 Bluehead Sucker (Catostomus discobolus). MtDNA revealed three geomorphically defined evolutionarily significant units (ESUs): Bonneville Basin, upper Little Colorado River and the remaining Colorado River Basin. Microsatellite analyses (16 loci) reinforced distinctiveness of the Bonneville Basin and upper Little Colorado River, but subdivided the Colorado River Basin into seven management units (MUs). One represents a cline of three admixed gene pools comprising the mainstem and its lower-gradient tributaries. Six others are not only distinct genetically but also demographically (i.e. migrants/generation <9.7%). Two of these (i.e. Grand Canyon and Canyon de Chelly) are defined by geomorphology, two others (i.e. Fremont-Muddy and San Raphael rivers) are isolated by sharp declivities as they drop precipitously from the west slope into the mainstem Colorado/Green rivers, another represents an isolated impoundment (i.e. Ringdahl Reservoir), while the last corresponds to a recognized subspecies (i.e. Zuni River, NM). Historical legacies of endemic fishes (ESUs) and their evolutionary potential (MUs) are clearly represented in our data, yet their arbiter will be the unrelenting natural and anthropogenic water depletions that will precipitate yet another conservation conflict within this unique but arid region. © 2012 Blackwell Publishing Ltd.

  15. Monitoring of desert dune topography by multi angle sensors

    Science.gov (United States)

    Yun, J.; Kim, J.; Choi, Y.; Yun, H.

    2011-12-01

    Nowadays, the sandy desert is rapidly expanding world widely and results in a lot of risks in the socio-econimical aspects as well as the anthropogenic activities. For example, the increasing occurrences of mineral dust storm which presumably originated from the sandy deserts in northwest China become a serious threat in human activities as well as public health over Far East Asian area as the interpretation by the MODIS analysis (Zhang et al., 2007) and the particle trajectory simulation with HYSPLYT (HYbrid Single-Particle Lagrangian Integrated Trajectory) (Kim et al., 2011) identified. Since the sand dune activity has been recognized as an essential indicator of the progressive desertification, it is important to establish the monitoring method for the variations of topographic properties by the dune activities such as local roughness. Thus it will provide the crucial data about the extent and the transition of sandy desert. For example, it is well known the aerodynamic roughness lengths Zo which can be driven from the specialized sensor such as POLDER (POLarization and Directionality of the Earth's Reflectances) is essential to understand desert dune characteristics. However, for the multi temporal observation of dune fields, the availability of data set to extract Zo is limited. Therefore, we employed MISR (Multi angle imaging Spectro Radiometer) image sequence to extract multi angle topographic parameters such as NDAI (Normalized Difference Angular Index) or the variation of radiance with the viewing geometry which are representing the characteristics of target desert topography instead of Zo. In our approach, NDAI were expanded to the all viewing angles and then compared over the target sandy desert and the surrounding land covers. It showed very strong consistencies according to the land cover type and especially over the dynamic dune fields. On the other hands, the variation of NDAIs of sandy desert combining with the metrological observations were

  16. Tree planting in deserts and utilization of atomic energy

    International Nuclear Information System (INIS)

    Hattori, Sadao; Minato, Akio; Hashizume, Kenichi; Handa, Norihiko.

    1991-01-01

    Global environment problems are discussed actively, concretely, those are the warming of the earth, the advance of desertification, the damage due to acid rain, the decrease of tropical forests, the pollution of sea, the depletion of ozone layer and so on. Most of these phenomena advance gradually. However, the advance of desertification is different from other phenomena in that the people in the areas concerned are deprived of their living space and even their lives are threatened at this moment. Desertification is advancing on global scale, and its rate is estimated to be 60,000 km 2 yearly. Especially the area where the advance is remarkable is the southern edge of Sahara Desert, which advances southward at 10-30 km in one year. Recently also in Japan, the interest in the prevention of desertification has become high, and the experiment on tree planting in a desert using a huge desert dome of the Institute of Physical and Chemical Research, 'Desert Aquanet concept' of Shimizu Construction Co., Ltd., 'Sahara green belt project' of the Ministry of International Trade and Industry and so on were published. Water and energy for tree planting in deserts, utilization of atomic energy for seawater desalination and the technical fields to which Japan can contribute are reported. (K.I.)

  17. Water use sources of desert riparian Populus euphratica forests.

    Science.gov (United States)

    Si, Jianhua; Feng, Qi; Cao, Shengkui; Yu, Tengfei; Zhao, Chunyan

    2014-09-01

    Desert riparian forests are the main body of natural oases in the lower reaches of inland rivers; its growth and distribution are closely related to water use sources. However, how does the desert riparian forest obtains a stable water source and which water sources it uses to effectively avoid or overcome water stress to survive? This paper describes an analysis of the water sources, using the stable oxygen isotope technique and the linear mixed model of the isotopic values and of desert riparian Populus euphratica forests growing at sites with different groundwater depths and conditions. The results showed that the main water source of Populus euphratica changes from water in a single soil layer or groundwater to deep subsoil water and groundwater as the depth of groundwater increases. This appears to be an adaptive selection to arid and water-deficient conditions and is a primary reason for the long-term survival of P. euphratica in the desert riparian forest of an extremely arid region. Water contributions from the various soil layers and from groundwater differed and the desert riparian P. euphratica forests in different habitats had dissimilar water use strategies.

  18. Tree planting in deserts and utilization of atomic energy

    Energy Technology Data Exchange (ETDEWEB)

    Hattori, Sadao; Minato, Akio [Central Research Inst. of Electric Power Industry, Tokyo (Japan); Hashizume, Kenichi; Handa, Norihiko

    1991-06-01

    Global environment problems are discussed actively, concretely, those are the warming of the earth, the advance of desertification, the damage due to acid rain, the decrease of tropical forests, the pollution of sea, the depletion of ozone layer and so on. Most of these phenomena advance gradually. However, the advance of desertification is different from other phenomena in that the people in the areas concerned are deprived of their living space and even their lives are threatened at this moment. Desertification is advancing on global scale, and its rate is estimated to be 60,000 km{sup 2} yearly. Especially the area where the advance is remarkable is the southern edge of Sahara Desert, which advances southward at 10-30 km in one year. Recently also in Japan, the interest in the prevention of desertification has become high, and the experiment on tree planting in a desert using a huge desert dome of the Institute of Physical and Chemical Research, 'Desert Aquanet concept' of Shimizu Construction Co., Ltd., 'Sahara green belt project' of the Ministry of International Trade and Industry and so on were published. Water and energy for tree planting in deserts, utilization of atomic energy for seawater desalination and the technical fields to which Japan can contribute are reported. (K.I.).

  19. Production of desert rose seedlings in different potting media

    Directory of Open Access Journals (Sweden)

    Ronan Carlos Colombo

    2017-09-01

    Full Text Available Over the past decade the desert rose received fame in the flower market due to its striking and sculptural forms; however, the commercial production of these species is quite recent and little is known about its crop management, including substrates recommendation. The objectives of this study were to investigate the effect of different substrates on desert rose seed germination and production of its seedlings. Experiment I: freshly harvested seeds of desert rose were sown in different substrates e.g. sand, coconut fiber, semi-composted pine bark, sand + coconut fiber, semi-composted pine bark + sand and coconut fiber + semicomposted pine bark. These substrates were evaluated to study the emergence percentage of seeds, initial growth of seedlings and seedling emergence speed index (ESI. Experiment II: desert rose from the experiment I were transferred to plastic pots filled with the same substrates as in experiment I. The pH and electrical conductivity (EC of the substrates were noted every 30 days while the growth parameters of seedlings were recorded after 240 days. Results from experiment I showed higher germination rate and seedling growth in substrates containing semi-composted pine bark. Similarly, in experiment II, better quality seedlings were observed in substrates containing semi-composted pine bark. Thus, for desert rose seed germination and seedling growth, it is recommended to use substrates containing semi-composted pine bark.

  20. Atmospheric Surface Layer Characterization: Preliminary Desert Lapse Rate Study 22-25 August 2000

    National Research Council Canada - National Science Library

    Elliott, Doyle

    2003-01-01

    Results of the August 2000 Desert Lapse Rate (DLR) Experiment are presented. The DLR Experiment was performed to document the night-to-day transition effects on the desert Atmospheric Surface Layer (ASL...

  1. The Ocean deserts:salt budgets of northern subtropical oceans and their

    KAUST Repository

    Carton, Jim

    2011-04-09

    The Ocean deserts: salt budgets of northern subtropical oceans and their relationship to climate variability The high salinity near surface pools of the subtropical oceans are the oceanic deserts, with high levels of evaporation and low levels of precip

  2. Out of the Desert: My Journey from Nomadic Bedouin to the Heart of Global Oil

    KAUST Repository

    Al-Naimi, Ali Ibrahim

    2017-01-01

    Arabian deserts. From his first job as a shepherd boy to his appointment to one of the most powerful political and economic jobs in the world, Out of the Desert charts Al-Naimi's extraordinary rise to power.

  3. Metallogenic condition and regularity of inter layered oxidation zone-type sandstone uranium deposit in southwestern part of Turpan-Hami basin, Northwestern China

    International Nuclear Information System (INIS)

    Xiang Weidong; Chen Zhaobo; Chen Zuyi; Yin Jinshuang

    2001-01-01

    Regional geological surveying and drilling evaluation in recent years show that there are very large potential resources of sandstone-type uranium deposits in the southwestern part of Turpan-Hami basin. According to the characteristics of tectonic evolution and sedimentary cover of the basin, the evolution stages and types of the basin are divided, and the favorable development stages for the ore-bearing formation and the formation of uranium deposits in the evolution process are identified. The metallogenic conditions of uranium deposits are deeply discussed from four aspects: basic tectonics, paleoclimate evolution, hydrogeology and uranium source of the region. All these have laid an important foundation for accurate prediction and evaluation of uranium resources in this region. The research indicates that the uranium metallogeny is a process of long-term, multi-stage and pulsation. The authors try to ascertain the role of organic matter in concentrating uranium. The organic matter is of humic type in sandstone host-rock in the studied area, whose original mother material mainly belongs to terrestrial high plant. The maturity of the organic matter is very low, being in low-grade stage of thermal evolution. Correlation analysis and separation experiments show that uranium concentration is closely related with the organic matter, and the organic matter in uranium ore is mainly in the form of humic acid adsorption and humate. For this reason the total organic carbon content is often increased in the geochemical redox zone in epigenetic sandstone-type uranium deposits. It is suggested that the north of China is of great potential for sandstone-type uranium resources

  4. Research on Structure Innovation of Agricultural Organization in China's Southwestern Mountainous Regions

    OpenAIRE

    Du, Qiang; Luo, Min; Wang, Ping

    2012-01-01

    Taking agricultural organization in China's southwestern mountainous regions as research object, on the basis of analysis of the status quo of agricultural organization development in China's southwestern mountainous regions, we use related theoretical knowledge on economics and organization science, we probe into the process of innovation and mechanism of action concerning the structure of agricultural organization in China's southwestern mountainous regions over the past 30 years. Finally w...

  5. X-36 in Flight over Mojave Desert

    Science.gov (United States)

    1997-01-01

    The unusual lines of the X-36 technology demonstrator contrast sharply with the desert floor as the remotely piloted aircraft scoots across the California desert at low altitude during a research flight on October 30, 1997. The NASA/Boeing X-36 Tailless Fighter Agility Research Aircraft program successfully demonstrated the tailless fighter design using advanced technologies to improve the maneuverability and survivability of possible future fighter aircraft. The program met or exceeded all project goals. For 31 flights during 1997 at the Dryden Flight Research Center, Edwards, California, the project team examined the aircraft's agility at low speed / high angles of attack and at high speed / low angles of attack. The aircraft's speed envelope reached up to 206 knots (234 mph). This aircraft was very stable and maneuverable. It handled very well. The X-36 vehicle was designed to fly without the traditional tail surfaces common on most aircraft. Instead, a canard forward of the wing was used as well as split ailerons and an advanced thrust-vectoring nozzle for directional control. The X-36 was unstable in both pitch and yaw axes, so an advanced, single-channel digital fly-by-wire control system (developed with some commercially available components) was put in place to stabilize the aircraft. Using a video camera mounted in the nose of the aircraft and an onboard microphone, the X-36 was remotely controlled by a pilot in a ground station virtual cockpit. A standard fighter-type head-up display (HUD) and a moving-map representation of the vehicle's position within the range in which it flew provided excellent situational awareness for the pilot. This pilot-in-the-loop approach eliminated the need for expensive and complex autonomous flight control systems and the risks associated with their inability to deal with unknown or unforeseen phenomena in flight. Fully fueled the X-36 prototype weighed approximately 1,250 pounds. It was 19 feet long and three feet high with

  6. Cryophenomena in the Cold Desert of Atacama

    Science.gov (United States)

    Buchroithner, Dr.; Trombotto, Dr.

    2012-04-01

    The study area of the Valle de Barrancas Blancas in the High Atacama Andes of Chile (68°39' W, 27°02' S), a kind of Patagonian "bajo sin salida", shows well preserved landforms resulting from a combination of slope, eolian, lacustrine/litoral, fluvial, glacial and periglacial regimes. They permit the reconstruction of geomorphological processes within this isolated catchment of approximately 160 km2. The mean annual air temperature varies between -2 and -4 °C and the precipitation is approximately 150 mm/a. Snowfall is frequent but the snow is quickly sublimated, redeposited and/or covered by cryosediments, i.e. mainly pumice pebbles. Water bodies present icings, even in summer. Regarding its climatic conditions the study area represents an extremely cold desertic region. Extremophile microfauna was also found. The area displays both in situ mountain permafrost and creeping permafrost. The active layer is 30 to 45 cm thick. It is a periglacial macro-environment where interdependent processes, and not only cryogenic processes but also erosion and eolian deposition and the action of fluvial washout mainly caused by precipitation, accumulation, retransportation/redeposition and melting of snow, play an important role. The cryogenic geomorphology of the Valle de Barrancas Blancas is varied and contains microforms such as patterned ground and microforms caused by cryoturbation, as well as mesoforms like rockglaciers and cryoplanation surfaces. Slopes are strongly affected by gelifluction. New cryoforms in South America and in the Southern Hemisphere like the Atacama Pingo (Pingo atacamensis) and Permafrosted Dunes ("Dunas heladas") were found. Intense niveo-eolian processes participate in the erosion of preexisting landforms, in the formation of subterraneous ice layers, and the retransportation/redeposition of snow and sediments. Studies of this periglacial environment are crucial for the understanding of Tundrean paleoenvironments and Martian conditions.

  7. Condition-dependent clutch desertion in Great Tit (Parus major) females subjected to human disturbance

    OpenAIRE

    2011-01-01

    Abstract Nest desertion behaviour in relation to body condition and timing of breeding was studied in Great Tit (Parus major) females during two breeding seasons. Desertion, most likely unintentionally provoked by catching females during the incubation period, occurred at a very high rate with 41.2 and 25.6% of deserted first clutches in the two study years. The association between desertion probability, body condition (index calculated as residuals from the regression of body mass...

  8. Growth responses of five desert plants as influenced by biological soil crusts from a temperate desert, China

    Science.gov (United States)

    Zhang, Yuanming; Belnap, Jayne

    2015-01-01

    In almost all dryland systems, biological soil crusts (biocrusts) coexist alongside herbaceous and woody vegetation, creating landscape mosaics of vegetated and biocrusted patches. Results from past studies on the interaction between biocrusts and vascular plants have been contradictory. In the Gurbantunggut desert, a large temperate desert in northwestern China, well-developed lichen-dominated crusts dominate the areas at the base and between the sand dunes. We examined the influence of these lichen-dominated biocrusts on the germination, growth, biomass accumulation, and elemental content of five common plants in this desert: two shrubs (Haloxylon persicum, Ephedra distachya) and three herbaceous plants (Ceratocarpus arenarius, Malcolmia africana and Lappula semiglabra) under greenhouse conditions. The influence of biocrusts on seed germination was species-specific. Biocrusts did not affect percent germination in plants with smooth seeds, but inhibited germination of seeds with appendages that reduced or eliminated contact with the soil surface or prevented seeds from slipping into soil cracks. Once seeds had germinated, biocrusts had different influences on growth of shrub and herbaceous plants. The presence of biocrusts increased concentrations of nitrogen but did not affect phosphorus or potassium in tissue of all tested species, while the uptake of the other tested nutrients was species-specific. Our study showed that biocrusts can serve as a biological filter during seed germination and also can influence growth and elemental uptake. Therefore, they may be an important trigger for determining desert plant diversity and community composition in deserts.

  9. Strategy for the development and management of deserts

    Energy Technology Data Exchange (ETDEWEB)

    1978-02-01

    Recommendations from the June 1977 Conference on Alternative Strategies for Desert Development and Management apply primarily to arid lands, although some can be applied to true desert with no vegetation as well. The causes of desertification are reviewed and corrective measures suggested for both developed and developing countries. A range of strategies is proposed, but all are based on the efficient use of water and most are concerned with water used for agricultural purposes. The conference papers also addressed water management, agricultural development, field crops versus animal husbandry, grazing, land use and allocation, wild life resources, industry coastal resources, tourism, energy and minerals, and establishing the infrastructure needed to improve and retain desert health.

  10. Concentration of plutonium in desert plants from contaminated area

    International Nuclear Information System (INIS)

    Xu Hui; Jin Yuren; Tian Mei; Li Weiping; Zeng Ke; Wang Yaoqin; Wang Yu

    2012-01-01

    The investigation of plutonium in desert plants from contaminated sites contributes to the evaluation of its pollution situation and to the survey of plutonium hyper accumulator. The concentration of 239 Pu in desert plants collected from a contaminated site was determined, and the influence factors were studied. The concentration of 239 Pu in plants was (1.8±4.9) Bq/kg in dry weight, and it means that the plants were contaminated, moreover, the resuspension results in dramatic plutonium pollution of plant surface. The concentration of plutonium in plants depends on species, live stages and the content of plutonium in the rhizosphere soil. The concentration of plutonium in herbage is higher than that in woody plant, and for the seven species of desert plants investigated, it decreases in the order of Hexinia polydichotoma, Phragmites australis, Halostashys caspica, Halogeton arachnoideus, Lycium ruthenicum, Tamarix hispida and Calligonum aphyllum. (authors)

  11. Lizard burrows provide thermal refugia for larks in the Arabian desert

    NARCIS (Netherlands)

    Williams, JB; Tieleman, BI; Shobrak, M

    A common perception is that desert birds experience greater extremes of heat and aridity than their mammalian counterparts, in part, because birds do not use burrows as a refuge from the desert environment. We report observations of Dunn's Larks (Eremalauda dunni), Bar-tailed Desert Larks (Ammomanes

  12. 76 FR 8730 - Desert Southwest Customer Service Region-Rate Order No. WAPA-151

    Science.gov (United States)

    2011-02-15

    ... DEPARTMENT OF ENERGY Western Area Power Administration Desert Southwest Customer Service Region.... Jack Murray, Rates Manager, Desert Southwest Customer Service Region, Western Area Power Administration... ancillary service rates for the Desert Southwest Customer Service Region in accordance with section 302 of...

  13. 76 FR 29153 - Revisions to the California State Implementation Plan, Mojave Desert Air Quality Management District

    Science.gov (United States)

    2011-05-20

    ... the California State Implementation Plan, Mojave Desert Air Quality Management District AGENCY... approve revisions to the Mojave Desert Air Quality Management District (MDAQMD) portion of the California... approving with the dates that they were adopted by the Mojave Desert Air Quality Management District (MDAQMD...

  14. Middle-Late Holocene environmental history of Kulunda (Southwestern Siberia): vegetation, climate, humans

    Science.gov (United States)

    Rudaya, N.; Nazarova, L.; Papin, D.; Nourgaliev, D.

    2012-04-01

    Environmental reconstruction of Mid-Late Holocene vegetation and climate was inferred from pollen records of Lake Big Yarovoe (Kulunda steppe, Southwestern Siberia). Reconstruction suggests generally prevalence of steppe during last 4.45 ka. Relatively warm and dry climate, open semi-desert and dry steppes with patchy birch forest spread between 4.45 and 3.80 ka BP. The largest development of conifers forest started in Kulunda after 3.80 ka BP. Constant presence of dark-coniferous trees Abies and especially Picea between 3.80 and 2.7 ka BP indicates the most humid period in the region during studied time. Onset of the Late Holocene is characterised by dominance of steppe with birch and pine forests in lowlands and river valleys. After AD 1860, open steppe and semi-desert vegetation with fragmentary birch forest have been dominated parallel to sharp reduction of conifers in Kulunda. These results are in agreement with general scheme of Holocene environmental history of surrounding areas including Baraba forest-steppe, Kazakh Upland and Altai Mountains. Territory of Kulunda consists many archaeological sites of Bronze, Iron and Middle Ages. Second half of Bronze Age (4.45-3.80 ka BP) was represented by local human cultures or migrants from the North Kazakhstan. The main archaeological culture of Kulunda alike in the whole Ob`-Irtysh interfluve in this period was Elunino culture. The economical activities of Elunino community were connected with animal breeding especially with sheep and goats. The most humid period (~1795-710 BC; 3.8-2.7 ka BP) in Kulunda corresponded to the end of early Bronze Age and to the onset of the Iron Age. In 18 century BC Andronovo culture, associated with the Indo-Iranians and migrants from Central Kazakhstan, spread in the region. Cattle breeding economy was distinctive features of Andronovo people, however, increase of sheep, goats and horses with transition to nomadic life style was characteristic of the late Bronze Age. This trend is in

  15. Recovery of compacted soils in Mojave Desert ghost towns.

    Science.gov (United States)

    Webb, R.H.; Steiger, J.W.; Wilshire, H.G.

    1986-01-01

    Residual compaction of soils was measured at seven sites in five Mojave Desert ghost towns. Soils in these Death Valley National Monument townsites were compacted by vehicles, animals, and human trampling, and the townsites had been completely abandoned and the buildings removed for 64 to 75 yr. Recovery times extrapolated using a linear recovery model ranged from 80 to 140 yr and averaged 100 yr. The recovery times were related to elevation, suggesting freeze-thaw loosening as an important factor in ameliorating soil compaction in the Mojave Desert. -from Authors

  16. Natural product diversity of actinobacteria in the Atacama Desert.

    Science.gov (United States)

    Rateb, Mostafa E; Ebel, Rainer; Jaspars, Marcel

    2018-02-14

    The Atacama Desert of northern Chile is considered one of the most arid and extreme environment on Earth. Its core region was described as featuring "Mars-like" soils that were at one point deemed too extreme for life to exist. However, recent investigations confirmed the presence of diverse culturable actinobacteria. In the current review, we discuss a total of 46 natural products isolated to date representing diverse chemical classes characterized from different actinobacteria isolated from various locations in the Atacama Desert. Their reported biological activities are also discussed.

  17. Winter precipitation and fire in the Sonoran Desert

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, G.F.; Vint, M.K.

    1987-01-01

    Historical fire and climate records from the Arizona Upland portion of the Tonto National forest were used to test the hypothesis that fires burn larger areas in the Sonoran Desert after two wet winters than after one. We found that many more hectares burn in years following two winters that are wetter than normal, than during any other years. We agree with other ecologists, that desert fire occurrence is probably related to increased production of winter annual plants, and we suggest ways that the relationship may be clarified.

  18. Naturalisation, Desert, and the Symbolic Meaning of Citizenship

    DEFF Research Database (Denmark)

    Lægaard, Sune

    2012-01-01

    of naturalisation requirements as involving notions of desert and asks what these developments imply about the meaning of citizenship. Naturalisation marks the boundary of society understood as a political community, i.e. a civic rather than territorial boundary. How this boundary is policed and on the basis...... that the introduction of naturalisation tests and other desert-based naturalisation requirements imply that citizenship comes to have different symbolic meanings for native born citizens and naturalised citizens because such requirements distinguish between volitional or ‘earned’ and ascriptive or ‘natural’ citizenship...

  19. Estimating Winter Annual Biomass in the Sonoran and Mojave Deserts with Satellite- and Ground-Based Observations

    Directory of Open Access Journals (Sweden)

    Bradley C. Reed

    2013-02-01

    Full Text Available Winter annual plants in southwestern North America influence fire regimes, provide forage, and help prevent erosion. Exotic annuals may also threaten native species. Monitoring winter annuals is difficult because of their ephemeral nature, making the development of a satellite monitoring tool valuable. We mapped winter annual aboveground biomass in the Desert Southwest from satellite observations, evaluating 18 algorithms using time-series vegetation indices (VI. Field-based biomass estimates were used to calibrate and evaluate each algorithm. Winter annual biomass was best estimated by calculating a base VI across the period of record and subtracting it from the peak VI for each winter season (R2 = 0.92. The normalized difference vegetation index (NDVI derived from 8-day reflectance data provided the best estimate of winter annual biomass. It is important to account for the timing of peak vegetation when relating field-based estimates to satellite VI data, since post-peak field estimates may indicate senescent biomass which is inaccurately represented by VI-based estimates. Images generated from the best-performing algorithm show both spatial and temporal variation in winter annual biomass. Efforts to manage this variable resource would be enhanced by a tool that allows the monitoring of changes in winter annual resources over time.

  20. Plant population and habitat characteristics of the endemic Sonoran Desert cactus Peniocereus striatus in Organ Pipe Cactus National Monument, Arizona

    Science.gov (United States)

    Anderson, Greta; Rutman, Sue; Munson, Seth M.

    2010-01-01

    Peniocereus striatus (Brandegee) Buxb. (Cactaceae) is an endemic Sonoran Desert cactus that reaches its northern range limit in southwestern Arizona. One U.S. population occupies a small area of Organ Pipe Cactus National Monument near the U.S./Mexico international boundary, which has been monitored since 1939. An extensive survey conducted in 2002, covering 177 ha, resulted in the discovery of 88 new plants, in addition to the relocation of 57 plants found in previous surveys. Despite potential increases in population size and spatial distribution, mean plant height and number of basal stems has not significantly changed in recent years. Bud scars revealed that a majority of the population was sexually mature. Peniocereus striatus occurrence increased with decreasing slope, spanned every slope aspect, and was highest on rocky soils, but was noticeably low on west and northwest slopes and areas where severe land degradation had previously occurred. Over half of P. striatus plants were nursed by shrubs and subshrubs, while 40% occurred under leguminous trees. A severe frost in January 2002 top-killed 19% of the population, with the greatest damage in drainage bottoms. However, long-term (1944–2002) climate records show that there has been an overall increase in the number of frost free days in the region, which, coupled with land use change, has implications for the future health of this population.

  1. Multiple factors affect a population of Agassiz's desert tortoise (Gopherus agassizii) in the Northwestern Mojave Desert

    Science.gov (United States)

    Berry, Kristin H.; Yee, Julie L.; Coble, Ashley A.; Perry, William M.; Shields, Timothy A.

    2013-01-01

    Numerous factors have contributed to declines in populations of the federally threatened Agassiz's Desert Tortoise (Gopherus agassizii) and continue to limit recovery. In 2010, we surveyed a low-density population on a military test facility in the northwestern Mojave Desert of California, USA, to evaluate population status and identify potential factors contributing to distribution and low densities. Estimated densities of live tortoises ranged spatially from 1.2/km2 to 15.1/km2. Although only one death of a breeding-age tortoise was recorded for the 4-yr period prior to the survey, remains of 16 juvenile and immature tortoises were found, and most showed signs of predation by Common Ravens (Corvus corax) and mammals. Predation may have limited recruitment of young tortoises into the adult size classes. To evaluate the relative importance of different types of impacts to tortoises, we developed predictive models for spatially explicit densities of tortoise sign and live tortoises using topography (i.e., slope), predators (Common Raven, signs of mammalian predators), and anthropogenic impacts (distances from paved road and denuded areas, density of ordnance fragments) as covariates. Models suggest that densities of tortoise sign increased with slope and signs of mammalian predators and decreased with Common Ravens, while also varying based on interaction effects involving these predictors as well as distances from paved roads, denuded areas, and ordnance. Similarly, densities of live tortoises varied by interaction effects among distances to denuded areas and paved roads, density of ordnance fragments, and slope. Thus multiple factors predict the densities and distribution of this population.

  2. Lessons learned from oxygen isotopes in modern precipitation applied to interpretation of speleothem records of paleoclimate from eastern Asia

    Science.gov (United States)

    Dayem, Katherine E.; Molnar, Peter; Battisti, David S.; Roe, Gerard H.

    2010-06-01

    values and monthly precipitation amounts can be applied to past conditions, differences of at least 50% in mean annual precipitation would be required to explain the δ18O variations on orbital time scales, which are implausibly large and inconsistent with published GCM results. Similarly, plausible amplitudes of seasonal cycles in amounts or in seasonal variations in δ18O values can account for less than half of the 4-5‰ difference between glacial and interglacial δ18O values from speleothems in China. If seasonal cycles in precipitation account for the amplitudes of δ18O values on paleoclimate timescales, they might do so by extending or contracting the durations of seasons (a frequency modulation of the annual cycle), but not by simply varying the amplitudes of the monthly rainfall amounts or monthly average δ18O values (amplitude modulation). Allowing that several processes can affect seasonal variability in isotopic content, we explore the possibility that one or more of the following processes contribute to variations in δ18O values in Chinese cave speleothems: different source regions of the precipitation, which bring different values of δ18O in vapor; different pathways between the moisture source and the paleorecord site along which exchange of 18O between vapor, surface water, and condensate might differ; a different mix of processes involving condensation and evaporation within the atmosphere; or different types of precipitation. Each may account for part of the range of δ18O values revealed by speleothems, and each might contribute to seasonal differences between past and present that do not scale with monthly or even seasonal precipitation amounts.

  3. Geophysical imaging of the lacustrine sediments deposited in the La Calderilla Volcanic Caldera (Gran Canaria Island, Spain) for paleoclimate research

    Science.gov (United States)

    Himi, Mahjoub; Rodríguez-González, Alejandro; Criado, Constantino; Tapias, Josefina C.; Ravazzi, Cesare; Pérez-Torrado, Francisco; Casas, Albert

    2016-04-01

    The discovery of well-preserved maar structures is important not only for studying the eruptive activity and formation of volcanoes, but also for paleoclimate research, since laminated maar lake sediments may contain very detailed archives of climate and environmental history. Maars are a singular type of volcanic structure generated by explosive phreatomagmatic eruptions as a result of interaction between rising magma and groundwater. This kind of structures are characterised by circular craters, often filled with water and/or lacustrine sediments and surrounded by a ring of pyroclastic deposits.Recently a borehole was drilled at the bottom of La Calderilla volcanic complex which penetrated about 8.7 m in its sedimentary sequence and paleobotanical study has supplied the first evidence of paleoenvironmental evolution during the Holocene on the Gran Canaria Island. This survey, however, did not penetrate into the substrate because the total thickness of the sedimentary fill was unknown. Since the age of formation of La Calderilla volcanic complex based on K/Ar dating is about 85,000 years (Upper Pleistocene), the possibility of its sedimentary fill extends beyond of the Holocene is extremely attractive, since, for example, there are few paleoenvironmental data regarding how much the last glaciation that affected the Canary Islands. In these circumstances, the knowledge of the total thickness of the lacustrine sediments is crucial to design a deeper borehole in the next future. Therefore, the subsurface characterisation provided by geophysics is essential for determining thickness and geometry of the sedimentary filling. Multielectrode ERT method was used to obtain five 2-D resistivity cross-sections into La Calderilla volcanic caldera. An Iris Syscal Pro resistivity system with 48 electrodes connected to a 94 m long cable (2m electrode spacing) in Wenner-Schlumberger configuration for an investigation depth of about 20 m. Data quality (q Current injected was

  4. Evaluation of Sr/Ca-based paleoclimate reconstructions in modern and Medieval Diploria strigosa corals in the northeastern Caribbean

    Science.gov (United States)

    Xu, Y.; Pearson, S. P.; Kilbourne, K.

    2013-12-01

    period with initial U-series dates near the top of the cores ranging from 1277 × 5 A.D. to 1327 × 5 A.D. Initial Sr/Ca results from the first sub-fossil coral have a seasonal range of 2.65 × 0.27 °C when converted to temperature units with our modern calibration, indicating no significant change from modern times. However, the mean Sr/Ca for this coral is very high (9.388 mmol/mol) compared to the modern corals. We explore the potential causes for this discrepancy in our study. Because reconstructing the mean SST during the Medieval Climate Anomaly may be difficult without temporal overlap with modern corals, our focus is on interannual variability. The coral Sr/Ca based monthly SST anomalies for both modern and sub-fossil corals have larger interannual variances than the instrumental record. One explanation for this is that the SSTs derived from sub-fossil corals are local data for which one expects larger variances than the instrumental data averaged over a 2 x 2 ° grid. This species shows great promise for future paleoclimate reconstructions.

  5. Provenance and recycling of Arabian desert sand

    Science.gov (United States)

    Garzanti, Eduardo; Vermeesch, Pieter; Andò, Sergio; Vezzoli, Giovanni; Valagussa, Manuel; Allen, Kate; Kadi, Khalid A.; Al-Juboury, Ali I. A.

    2013-05-01

    This study seeks to determine the ultimate origin of aeolian sand in Arabian deserts by high-resolution petrographic and heavy-mineral techniques combined with zircon U-Pb geochronology. Point-counting is used here as the sole method by which unbiased volume percentages of heavy minerals can be obtained. A comprehensive analysis of river and wadi sands from the Red Sea to the Bitlis-Zagros orogen allowed us to characterize all potential sediment sources, and thus to quantitatively constrain provenance of Arabian dune fields. Two main types of aeolian sand can be distinguished. Quartzose sands with very poor heavy-mineral suites including zircon occupy most of the region comprising the Great Nafud and Rub' al-Khali Sand Seas, and are largely recycled from thick Lower Palaeozoic quartzarenites with very minor first-cycle contributions from Precambrian basement, Mesozoic carbonate rocks, or Neogene basalts. Instead, carbonaticlastic sands with richer lithic and heavy-mineral populations characterize coastal dunes bordering the Arabian Gulf from the Jafurah Sand Sea of Saudi Arabia to the United Arab Emirates. The similarity with detritus carried by the axial Tigris-Euphrates system and by transverse rivers draining carbonate rocks of the Zagros indicates that Arabian coastal dunes largely consist of far-travelled sand, deposited on the exposed floor of the Gulf during Pleistocene lowstands and blown inland by dominant Shamal northerly winds. A dataset of detrital zircon U-Pb ages measured on twelve dune samples and two Lower Palaeozoic sandstones yielded fourteen identical age spectra. The age distributions all show a major Neoproterozoic peak corresponding to the Pan-African magmatic and tectonic events by which the Arabian Shield was assembled, with minor late Palaeoproterozoic and Neoarchean peaks. A similar U-Pb signature characterizes also Jafurah dune sands, suggesting that zircons are dominantly derived from interior Arabia, possibly deflated from the Wadi al

  6. Apparent Brecciation Gradient, Mount Desert Island, Maine

    Science.gov (United States)

    Hawkins, A. T.; Johnson, S. E.

    2004-05-01

    Mount Desert Island, Maine, comprises a shallow level, Siluro-Devonian igneous complex surrounded by a distinctive breccia zone ("shatter zone" of Gilman and Chapman, 1988). The zone is very well exposed on the southern and eastern shores of the island and provides a unique opportunity to examine subvolcanic processes. The breccia of the Shatter Zone shows wide variation in percent matrix and clast, and may represent a spatial and temporal gradient in breccia formation due to a single eruptive or other catastrophic volcanic event. The shatter zone was divided into five developmental stages based on the extent of brecciation: Bar Harbor Formation, Sols Cliffs breccia, Seeley Road breccia, Dubois breccia, and Great Head breccia. A digital camera was employed to capture scale images of representative outcrops using a 0.5 m square Plexiglas frame. Individual images were joined in Adobe Photoshop to create a composite image of each outcrop. The composite photo was then exported to Adobe Illustrator, which was used to outline the clasts and produce a digital map of the outcrop for analysis. The fractal dimension (Fd) of each clast was calculated using NIH Image and a Euclidean distance mapping method described by Bérubé and Jébrak (1999) to quantify the morphology of the fragments, or the complexity of the outline. The more complex the fragment outline, the higher the fractal dimension, indicating that the fragment is less "mature" or has had less exposure to erosional processes, such as the injection of an igneous matrix. Sols Cliffs breccia has an average Fd of 1.125, whereas Great Head breccia has an average Fd of 1.040, with the stages between having intermediate values. The more complex clasts of the Sols Cliffs breccia with a small amount (26.38%) of matrix material suggests that it is the first stage in a sequence of brecciation ending at the more mature, matrix-supported (71.37%) breccia of Great Head. The results of this study will be used to guide isotopic

  7. Examining the provenance of branched GDGTs in the Tagus River drainage basin and its outflow into the Atlantic Ocean over the Holocene to determine their usefulness for paleoclimate applications

    NARCIS (Netherlands)

    Warden, L.; Kim, J.-H; Zell, C.; Vis, G.-J.; de Stigter, H.C.; Bonnin, J.; Sinninghe Damste, J.S.

    2016-01-01

    The distributions of branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are transported from the soils where they are predominantly produced to marine sediments via rivers, have been applied in reconstructing mean annual air temperature (MAT) and pH of soils. However, paleoclimate

  8. Global Warming: The Instability of Desert Climate is Enhancing in the Northwest Area in China: A Case Study in the Desert Area in Northwestern China

    OpenAIRE

    Zhao-Feng Chang; Shu-Juan Zhu; Fu-Gui Han; Sheng-Nnian Zhong; Qiang-Qiang Wang; Jian-Hui Zhang

    2013-01-01

    To disclose the relation between the sandstorms change and the temperature changes, a case study in the desert area in northwestern china is investigated. The results showed that: the instability of climate in Minqin desert area is enhancing in the arid desert region in northwest China. Mainly as follows: Variation the annual extreme maximum temperature increasing. Variation of extreme minimum temperature also an increasing trend. Average visibility of sandstorms significantly reduced and the...

  9. Disposal and reclamation of southwestern coal and uranium wastes

    International Nuclear Information System (INIS)

    Wewerka, E.M.

    1979-01-01

    The types of solid wastes and effluents produced by the southwestern coal and uranium mining and milling industries are considered, and the current methods for the disposal and reclamation of these materials discussed. The major means of disposing of the solid wastes from both industries is by land fill or in some instances ponding. Sludges or aqueous wastes are normally discharged into settling and evaporative ponds. Basic reclamation measures for nearly all coal and uranium waste disposal sites include solids stabilization, compacting, grading, soil preparation, and revegetation. Impermeable liners and caps are beginning to be applied to disposal sites for some of the more harmful coal and uranium waste materials

  10. Factorial's composition of Lake Abha, Southwestern Saudi Arabia

    International Nuclear Information System (INIS)

    El-Beheiry, M.A.H

    2007-01-01

    The study analyzes the vegetation along Lake Abha in Southwestern Saudi Arabia. A total of 42 plant species were recorded. The annuals decrease and the biennials and perennials increase along the moisture gradient form the terraces to the free-water zone. Six vegetation clusters were identified. The most important are clusters which were identified by the presence of the following species: Phragmites australis, Juncus punctorius, Typha domingensis, Cyperus rotundus, Datura innoxia, Cynodon dactylon, Cornulaca monacantha and Potamogeton nododsus. Each of these communities has been analyzed by classification and ordination techniques and its habitat described and discussed. (author)

  11. Effects of altered temperature and precipitation on desert protozoa associated with biological soil crusts.

    Science.gov (United States)

    Darby, Brian J; Housman, David C; Zaki, Amr M; Shamout, Yassein; Adl, Sina M; Belnap, Jayne; Neher, Deborah A

    2006-01-01

    Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37 degrees C. Cysts survived the upper end of daily temperatures (37-55 degrees C), and could be stimulated to excyst if temperatures were reduced to 15 degrees C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert's temperature and precipitation regime.

  12. Pollination ecology of the rare desert species Eremosparton songoricum (Fabaceae

    Science.gov (United States)

    The pollination ecology of Eremosparton songoricum (Litv.) Vass., a rare desert species endemic to central Asia, was examined by a series of observational studies and manipulative experiments in two natural populations during 2007–2008. Results showed that the duration of flowering lasted 21 and 23 ...

  13. Ecological and evolutionary physiology of desert birds : A progress report

    NARCIS (Netherlands)

    Williams, JB; Tieleman, BI

    The adaptive significance of mechanisms of energy and water conservation among species of desert rodents, which avoid temperature extremes by remaining within a burrow during the day, is well established. Conventional wisdom holds that arid-zone birds, diurnal organisms that endure the brunt of

  14. Molecular mechanisms of foliar water uptake in a desert tree.

    Science.gov (United States)

    Yan, Xia; Zhou, Maoxian; Dong, Xicun; Zou, Songbing; Xiao, Honglang; Ma, Xiao-Fei

    2015-11-12

    Water deficits severely affect growth, particularly for the plants in arid and semiarid regions of the world. In addition to precipitation, other subsidiary water, such as dew, fog, clouds and small rain showers, may also be absorbed by leaves in a process known as foliar water uptake. With the severe scarcity of water in desert regions, this process is increasingly becoming a necessity. Studies have reported on physical and physiological processes of foliar water uptake. However, the molecular mechanisms remain less understood. As major channels for water regulation and transport, aquaporins (AQPs) are involved in this process. However, due to the regulatory complexity and functional diversity of AQPs, their molecular mechanism for foliar water uptake remains unclear. In this study, Tamarix ramosissima, a tree species widely distributed in desert regions, was investigated for gene expression patterns of AQPs and for sap flow velocity. Our results suggest that the foliar water uptake of T. ramosissima occurs in natural fields at night when the humidity is over a threshold of 85 %. The diurnal gene expression pattern of AQPs suggests that most AQP gene expressions display a circadian rhythm, and this could affect both photosynthesis and transpiration. At night, the PIP2-1 gene is also upregulated with increased relative air humidity. This gene expression pattern may allow desert plants to regulate foliar water uptake to adapt to extreme drought. This study suggests a molecular basis of foliar water uptake in desert plants. Published by Oxford University Press on behalf of the Annals of Botany Company.

  15. Trajectory and rate of desert vegetation response following cattle removal

    Science.gov (United States)

    Robert L. Minckley

    2013-01-01

    Cattle have grazed continuously over the past three centuries in the Sky Island region and most work has focused on how these grazers have affected riparian and grassland habitats. I examined the effects of grazing on a fuller spectrum of desert habitats that occur in the close proximity to the San Bernardino Valley of Mexico and the United States. Plots in each of...

  16. Electricity from the desert; Strom aus der Wueste

    Energy Technology Data Exchange (ETDEWEB)

    Schwarzburger, Heiko; Ullrich, Sven

    2013-06-15

    The North African sun seems ideal for photovoltaic use. However, photovoltaic modules must withstand extreme loads in the desert. [German] Die Sonne Nordafrikas scheint ideal fuer die Photovoltaik-Nutzung. Jedoch muessen Photovoltaik-Module in der Wueste extremen Belastungen standhalten.

  17. Cutaneous adenocarcinoma in a desert tortoise (Gopherus agassizii

    Directory of Open Access Journals (Sweden)

    Ashraf Abu-Seida

    2013-06-01

    Full Text Available This report describes the clinical and histopathological findings of a rare case of cutaneous adenocarcinoma in a 40-year-old desert tortoise. Surgical excision of the neoplasm improved the general health condition and locomotion of the tortoise although recurrence of the neoplasm had been recorded 1 year post-surgery.

  18. Antimicrobial Screening of Some Exotic Tree Species of Rajasthan Desert

    OpenAIRE

    B.B.S. Kapoor* and Shelja Pandita

    2013-01-01

    Antimicrobial screening of ethyl ether and alcoholic extracts of leaves of four selected exotic tree species growing inRajasthan Desert was carried out. Colophospermum mopane, Holoptelea integrifolia, Kigelia pinnata andPutranjiva roxburghii showed positive reactions against bacterial pathogens i.e. Staphylococcus aureus, Escherichiacoli and a fungal pathogen Candida albicans.

  19. Energetics and water relations ofN amib desert rodents

    African Journals Online (AJOL)

    and the possible effects of advective fog on the water balance of the .... Table 2 Energy balance of Namib desert rodents in the laboratory on a diet of air-dried bird seed and with, and with, ad lib water. .... responding mercury thermometer.

  20. Analysis of "The Wonderful Desert." Technical Report No. 170.

    Science.gov (United States)

    Green, G. M.; And Others

    This report presents a text analysis of "The Wonderful Desert," a brief selection from the "Reader's Digest Skill Builder" series. (The techniques used in arriving at the analysis are presented in a Reading Center Technical Report, Number 168, "Problems and Techniques of Text Analysis.") Tables are given for a…

  1. Academic Performance, School Desertion and Emotional Paradigm in University Students

    Science.gov (United States)

    Sosa, Emma Rosa Cruz; Barrientos, Laura Gática; Castro, Patricia Eugenia García; García, Jesús Hernández

    2010-01-01

    The present work aims to describe academic performance, school desertion and the emotional paradigm of the university students of the accounting school of the Benemérita Universidad Autónoma de Puebla (FCPBUAP). We have found that low academic performance is related to students' economic deficiency, which affects their concentration on their…

  2. Reestablishing healthy food retail: changing the landscape of food deserts.

    Science.gov (United States)

    Karpyn, Allison; Young, Candace; Weiss, Stephanie

    2012-02-01

    The term "food desert" was formally introduced into the lexicon in 1995 and has come to describe areas with limited access to affordable nutritious foods, particularly areas in lower-income neighborhoods. The definition has led to the development of national and regional maps that focus efforts on equity in food access. Recognition of food deserts also marks a strategic change in public health's approach to obesity prevention. Today's emphasis on prevention has shifted away from individual responsibility to the role of the environment in health promotion. A number of solutions are underway to address food deserts, including public–private financing programs, industry commitments, as well as local and regional efforts to put healthy food within reach. The promise of financing programs to facilitate development of healthy food markets in underserved communities is rooted in their potential to alleviate the grocery gap and address underlying environmental contributors to obesity and diet-related diseases, such as obesity and diabetes. As food desert mapping and related interventions expand, there remains a need for ongoing investigation of impacts and the mechanisms by which impacts are achieved.

  3. Biology of larks (Aves: Alaudidae) in the central Namib Desert ...

    African Journals Online (AJOL)

    The biology of six species of larks in the Namib Desert near Walvis Bay, South West Africa, was studied in 1964, 1965 and 1966. 2. All species reproduced following rainfall in summer and autumn months, with the appearance of green grass and abundant insects on which the birds fed. 3. The primarily insectivorous species ...

  4. Learning Desert Geomorphology Virtually versus in the Field

    Science.gov (United States)

    Stumpf, Richard J., II; Douglass, John; Dorn, Ronald I.

    2008-01-01

    Statistical analyses of pre-test and post-test results, as well as qualitative insight obtained by essays, compared introductory physical geography college students who learned desert geomorphology only virtually, in the field and both ways. With the exception of establishing geographic context, the virtual field trip was statistically…

  5. Extreme Arthropods: Exploring Evolutionary Adaptations to Polar and Temperate Deserts

    Science.gov (United States)

    Sandro, Luke; Constible, Juanita M.; Lee, Richard E., Jr.

    2007-01-01

    In this activity, Namib and Antarctic arthropods are used to illustrate several important biological principles. Among these are the key ideas that form follows function and that the environment drives evolution. In addition, students will discover that the climates of the Namib Desert and the Antarctic Peninsula are similar in several ways, and…

  6. Is climate change mitigation the best use of desert shrublands?

    Science.gov (United States)

    Susan E. Meyer

    2011-01-01

    In a world where the metrics of the carbon economy have become a major issue, it may come as a surprise that intact cold desert shrublands can sequester significant amounts of carbon, both as biomass and in the form of SOC (soil organic carbon). Xerophytic shrubs invest heavily in belowground biomass, placing fixed carbon in an environment where it turns over only very...

  7. Ecology and utilization of desert shrub rangelands in Iraq

    NARCIS (Netherlands)

    Thalen, Derk Catharinus Peter

    1979-01-01

    When grazing is the accepted land use, vegetation is the key resource. The present study deals with the desert shrub rangelands of lraq, which contain the major characteristics of such an area, having been under grazing for many centuries. Emphasis is given to the ecology and utilization of the

  8. Distribution and status of the desert-dwelling giraffe ( Giraffa ...

    African Journals Online (AJOL)

    The population density and distribution of desert dwelling giraffes was estimated in three study areas in the Hoanib River catchment, northwestern Namibia. Giraffe population densities (0.01 giraffe/km2) were equal to the lowest recorded in Africa with population numbers fluctuating over past decades. Sex ratios, herd sizes ...

  9. Impacts of tracked vehicles on sediment from a desert soil

    Science.gov (United States)

    Erek H. Fuchs; Karl M. Wood; Tim L. Jones; Brent Racher

    2003-01-01

    Off-road military vehicle traffic is a major consideration in the management of military lands. The objective of this study was to determine the impacts of military tracked M1A1 heavy combat tank vehicles on sediment loss from runoff, surface plant cover, and surface microtopography in a desert military training environment. A randomized block design was used which had...

  10. A habitat overlap analysis derived from Maxent for Tamarisk and the South-western Willow Flycatcher

    Science.gov (United States)

    Patricia York; Paul Evangelista; Sunil Kumar; James Graham; Curtis Flather; Thomas Stohlgren

    2011-01-01

    Biologic control of the introduced and invasive, woody plant tamarisk (Tamarix spp, saltcedar) in south-western states is controversial because it affects habitat of the federally endangered South-western Willow Flycatcher (Empidonax traillii extimus). These songbirds sometimes nest in tamarisk where floodplain-level invasion replaces native habitats. Biologic control...

  11. Pollen spectrum, a cornerstone for tracing the evolution of the eastern Central Asian desert

    Science.gov (United States)

    Lu, Kai-Qing; Xie, Gan; Li, Min; Li, Jin-Feng; Trivedi, Anjali; Ferguson, David K.; Yao, Yi-Feng; Wang, Yu-Fei

    2018-04-01

    The temperate desert in arid Central Asia (ACA) has acted as a thoroughfare for the ancient Silk Road and today's Belt and Road, linking economic and cultural exchanges between East and West. The interaction between human sustainable development and the dynamic change in the desert ecosystem in this region is an area of concern for governments and scientific communities. Nevertheless, the lack of a pollen spectrum of the dominant taxa within the temperate desert vegetation and a corresponding relation between pollen assemblages and specific desert vegetation types is an obstacle to further understanding the formation and maintenance of this desert ecosystem. In this work, we link pollen assemblages to specific desert vegetation types with a new pollen spectrum with specific pollen grains, specific plant taxa and related habitats, providing a solid foundation for further tracing the evolution of the desert ecosystem in eastern arid Central Asia.

  12. Implementation of higher-order vertical finite elements in ISSM v4.13 for improved ice sheet flow modeling over paleoclimate timescales

    Directory of Open Access Journals (Sweden)

    J. K. Cuzzone

    2018-05-01

    Full Text Available Paleoclimate proxies are being used in conjunction with ice sheet modeling experiments to determine how the Greenland ice sheet responded to past changes, particularly during the last deglaciation. Although these comparisons have been a critical component in our understanding of the Greenland ice sheet sensitivity to past warming, they often rely on modeling experiments that favor minimizing computational expense over increased model physics. Over Paleoclimate timescales, simulating the thermal structure of the ice sheet has large implications on the modeled ice viscosity, which can feedback onto the basal sliding and ice flow. To accurately capture the thermal field, models often require a high number of vertical layers. This is not the case for the stress balance computation, however, where a high vertical resolution is not necessary. Consequently, since stress balance and thermal equations are generally performed on the same mesh, more time is spent on the stress balance computation than is otherwise necessary. For these reasons, running a higher-order ice sheet model (e.g., Blatter-Pattyn over timescales equivalent to the paleoclimate record has not been possible without incurring a large computational expense. To mitigate this issue, we propose a method that can be implemented within ice sheet models, whereby the vertical interpolation along the z axis relies on higher-order polynomials, rather than the traditional linear interpolation. This method is tested within the Ice Sheet System Model (ISSM using quadratic and cubic finite elements for the vertical interpolation on an idealized case and a realistic Greenland configuration. A transient experiment for the ice thickness evolution of a single-dome ice sheet demonstrates improved accuracy using the higher-order vertical interpolation compared to models using the linear vertical interpolation, despite having fewer degrees of freedom. This method is also shown to improve a model's ability

  13. Implementation of higher-order vertical finite elements in ISSM v4.13 for improved ice sheet flow modeling over paleoclimate timescales

    Science.gov (United States)

    Cuzzone, Joshua K.; Morlighem, Mathieu; Larour, Eric; Schlegel, Nicole; Seroussi, Helene

    2018-05-01

    Paleoclimate proxies are being used in conjunction with ice sheet modeling experiments to determine how the Greenland ice sheet responded to past changes, particularly during the last deglaciation. Although these comparisons have been a critical component in our understanding of the Greenland ice sheet sensitivity to past warming, they often rely on modeling experiments that favor minimizing computational expense over increased model physics. Over Paleoclimate timescales, simulating the thermal structure of the ice sheet has large implications on the modeled ice viscosity, which can feedback onto the basal sliding and ice flow. To accurately capture the thermal field, models often require a high number of vertical layers. This is not the case for the stress balance computation, however, where a high vertical resolution is not necessary. Consequently, since stress balance and thermal equations are generally performed on the same mesh, more time is spent on the stress balance computation than is otherwise necessary. For these reasons, running a higher-order ice sheet model (e.g., Blatter-Pattyn) over timescales equivalent to the paleoclimate record has not been possible without incurring a large computational expense. To mitigate this issue, we propose a method that can be implemented within ice sheet models, whereby the vertical interpolation along the z axis relies on higher-order polynomials, rather than the traditional linear interpolation. This method is tested within the Ice Sheet System Model (ISSM) using quadratic and cubic finite elements for the vertical interpolation on an idealized case and a realistic Greenland configuration. A transient experiment for the ice thickness evolution of a single-dome ice sheet demonstrates improved accuracy using the higher-order vertical interpolation compared to models using the linear vertical interpolation, despite having fewer degrees of freedom. This method is also shown to improve a model's ability to capture sharp

  14. Geochemistry of buried river sediments from Ghaggar Plains, NW India: Multi-proxy records of variations in provenance, paleoclimate, and paleovegetation patterns in the Late Quaternary

    DEFF Research Database (Denmark)

    Singh, Ajit; Paul, Debajyoti; Sinha, Rajiv

    2016-01-01

    We report the first geochemical record in two drill-sediment cores from a buried channel in the Ghaggar Plains of NW India, which are used to infer variations in provenance, paleoclimate, and paleovegetation in the locality during the Late Quaternary. Aeolian sediments (~150 ka) in both the cores...... are overlain by fluvial sediments (~75 ka-recent). Major oxide compositions of the core sediments (n = 35) generally vary between that observed for the modern-day Ghaggar/Sutlej and Yamuna river sand. The isotopic composition (87Sr/86Sr: 0.7365 to 0.7783 and εNd: -14.6 to -19.0) of core sediments (n = 18......) suggest binary mixing of sediments from compositionally distinct Higher Himalaya (HH) and Lesser Himalaya (LH) endmembers in the catchment, and support involvement of a river system originating in the Himalayan hinterland. Distinctly higher 87Sr/86Sr and lower εNd in the core sediments during glacial...

  15. Biological soil crusts as an integral component of desert environments

    Science.gov (United States)

    Belnap, Jayne; Weber, Bettina

    2013-01-01

    The biology and ecology of biological soil crusts, a soil surface community of mosses, lichens, cyanobacteria, green algae, fungi, and bacteria, have only recently been a topic of research. Most efforts began in the western U.S. (Cameron, Harper, Rushforth, and St. Clair), Australia (Rogers), and Israel (Friedmann, Evenari, and Lange) in the late 1960s and 1970s (e.g., Friedmann et al. 1967; Evenari 1985reviewed in Harper and Marble 1988). However, these groups worked independently of each other and, in fact, were often not aware of each other’s work. In addition, biological soil crust communities were seen as more a novelty than a critical component of dryland ecosystems. Since then, researchers have investigated many different aspects of these communities and have shown that although small to microscopic, biological soil crusts are critical in many ecological processes of deserts. They often cover most of desert soil surfaces and substantially mediate inputs and outputs from desert soils (Belnap et al. 2003). They can be a large source of biodiversity for deserts, as they can contain more species than the surrounding vascular plant community (Rosentreter 1986). These communities are important in reducing soil erosion and increasing soil fertility through the capture of dust and the fixation of atmospheric nitrogen and carbon into forms available to other life forms (Elbert et al. 2012). Because of their many effects on soil characteristics, such as external and internal morphological characteristics, aggregate stability, soil moisture, and permeability, they also affect seed germination and establishment and local hydrological cycles. Covering up to 70% of the surface area in many arid and semi-arid regions around the world (Belnap and Lange 2003), biological soil crusts are a key component within desert environments.

  16. 78 FR 65703 - Notice of Availability of the Idaho and Southwestern Montana Greater Sage-Grouse Draft Land Use...

    Science.gov (United States)

    2013-11-01

    ...] Notice of Availability of the Idaho and Southwestern Montana Greater Sage-Grouse Draft Land Use Plan... Environmental Impact Statement (EIS) for managing Greater Sage- Grouse (GRSG) in the Idaho and Southwestern... Southwestern Montana Greater Sage-Grouse Draft LUP Amendments/Draft EIS by any of the following methods: Email...

  17. Goods and services provided by native plants in desert ecosystems: Examples from the northwestern coastal desert of Egypt

    Directory of Open Access Journals (Sweden)

    Laila M. Bidak

    2015-01-01

    Full Text Available About one third of the earth’s land surface is covered by deserts that have low and variable rainfall, nutrient-poor soils, and little vegetation cover. Here, we focus on the goods and services offered by desert ecosystems using the northwestern coastal desert of Egypt extending from Burg El-Arab to El-Salloum as an example. We conducted field surveys and collected other data to identify the goods services and provided by native plant species. A total of 322 native plant species were compiled. The direct services provided by these native plants included sources of food, medicine, and energy; indirect vegetation services included promotion of biodiversity, water storage, and soil fertility. The plant diversity in this ecosystem provided economic service benefits, such as sources of fodder, fuel-wood, and traditional medicinal plants. Changes in land use and recent ill-managed human activities may influence the availability of these services and strongly impact biodiversity and habitat availability. Although deserts are fragile and support low levels of productivity, they provide a variety of goods and services whose continuing availability is contingent upon the adoption of rational land management practices.

  18. Effects of subsidized predators, resource variability, and human population density on desert tortoise populations in the Mojave Desert, USA

    Science.gov (United States)

    Esque, Todd C.; Nussear, Kenneth E.; Drake, K. Kristina; Walde, Andrew D.; Berry, Kristin H.; Averill-Murray, Roy C.; Woodman, A. Peter; Boarman, William I.; Medica, Phil A.; Mack, Jeremy S.; Heaton, Jill S.

    2010-01-01

    Understanding predator–prey relationships can be pivotal in the conservation of species. For 2 decades, desert tortoise Gopherus agassizii populations have declined, yet quantitative evidence regarding the causes of declines is scarce. In 2005, Ft. Irwin National Training Center, California, USA, implemented a translocation project including 2 yr of baseline monitoring of desert tortoises. Unusually high predation on tortoises was observed after translocation occurred. We conducted a retrospective analysis of predation and found that translocation did not affect the probability of predation: translocated, resident, and control tortoises all had similar levels of predation. However, predation rates were higher near human population concentrations, at lower elevation sites, and for smaller tortoises and females. Furthermore, high mortality rates were not limited to the National Training Center. In 2008, elevated mortality (as high as 43%) occurred throughout the listed range of the desert tortoise. Although no temporal prey base data are available for analysis from any of the study sites, we hypothesize that low population levels of typical coyote Canis latrans prey (i.e. jackrabbits Lepus californicus and other small animals) due to drought conditions influenced high predation rates in previous years. Predation may have been exacerbated in areas with high levels of subsidized predators. Many historical reports of increased predation, and our observation of a range-wide pattern, may indicate that high predation rates are more common than generally considered and may impact recovery of the desert tortoise throughout its range.

  19. 76 FR 50493 - Notice of Availability of the Record of Decision for the Desert Sunlight Holdings, LLC, Desert...

    Science.gov (United States)

    2011-08-15

    ... DEPARTMENT OF THE INTERIOR Bureau of Land Management [CACA-48649, LLCAD06000 L51010000 ER0000... right-of-way (ROW) application CACA-48649 for the Desert Sunlight Solar Farm Project (DSSF). The DSSF is... (CACA-052682) where the project would interconnect with the SCE regional transmission system. The DSSF...

  20. Deep groundwater quantity and quality in the southwestern US

    Science.gov (United States)

    Kang, M.; Ayars, J. E.; Jackson, R. B.

    2017-12-01

    Groundwater demands are growing in many arid regions and adaptation through the use of non-traditional resources during extreme droughts is increasingly common. One such resource is deep groundwater, which we define as deeper than 300 m and up to several kilometer-depths. Although deep groundwater has been studied in the context of oil and gas, geothermal, waste disposal, and other uses, it remains poorly characterized, especially for the purposes of human consumption and irrigation uses. Therefore, we evaluate deep groundwater quantity and quality within these contexts. We compile and analyze data from water management agencies and oil and gas-based sources for the southwestern US, with a detailed look at California's Central Valley. We also use crop tolerance thresholds to evaluate deep groundwater quality for irrigation purposes. We find fresh and usable groundwater volume estimates in California's Central Valley to increase by three- and four-fold respectively when depths of up to 3 km are considered. Of the ten basins in the southwestern US with the most data, we find that the Great Basin has the greatest proportions of fresh and usable deep groundwater. Given the potentially large deep groundwater volumes, it is important to characterize the resource, guard against subsidence where extracted, and protect it for use in decades and centuries to come.

  1. Evaluation of shrub and tree species used for revegetating copper mine wastes in the south-western United States. [Dodonea viscosa (L. ) Jacq. , Baccharis sarothroides Gray, Cerdicium microphyllum Torr. , and Nicotiana glauca Grah

    Energy Technology Data Exchange (ETDEWEB)

    Norem, M A; Day, A D; Ludeke, K L

    1982-12-01

    The revegetation work begun in 1970 at Cyprus Pima Mine, an open pit copper mine south-west of Tucson, Arizona, was evaluated to determine the effects of slope aspect and mining waste material on plant survival and growth. Only one shrub, Dodonea viscosa (L.) Jacq. (hopbush), survived on the east slope. Baccharis sarothroides Gray (desert broom) was prolific on the north aspect. Cerdicium microphyllum Torr. (palo verde) survived best on the east slope and Nicotiana glauca Grah. (desert tobacco) survived only on the north slope. The survival of the other tree species was not affected by slope aspect. Slope exposure did not affect tree size, except for Eucalyptus microtheca Muell. (tiny capsule eucalyptus) which grew larger on the north slope. E. rostrata Schlechtend (red gum eucalyptus) grew taller in overburden than in tailing on the east slope. Differences in soil material within each slope exposure did not significantly affect growth of the other tree species. In semi-arid regions, such as south-western Arizona, even slight differences in available moisture may determine the survival of a plant species in the area. (Refs. 11).

  2. Mineral compositions and sources of the riverbed sediment in the desert channel of Yellow River.

    Science.gov (United States)

    Jia, Xiaopeng; Wang, Haibing

    2011-02-01

    The Yellow River flows through an extensive, aeolian desert area and extends from Xiaheyan, Ningxia Province, to Toudaoguai, Inner Mongolia Province, with a total length of 1,000 km. Due to the construction and operation of large reservoirs in the upstream of the Yellow River, most water and sediment from upstream were stored in these reservoirs, which leads to the declining flow in the desert channel that has no capability to scour large amount of input of desert sands from the desert regions. By analyzing and comparing the spatial distribution of weight percent of mineral compositions between sediment sources and riverbed sediment of the main tributaries and the desert channel of the Yellow River, we concluded that the coarse sediment deposited in the desert channel of the Yellow River were mostly controlled by the local sediment sources. The analyzed results of the Quartz-Feldspar-Mica (QFM) triangular diagram and the R-factor models of the coarse sediment in the Gansu reach and the desert channel of the Yellow River further confirm that the Ningxia Hedong desert and the Inner Mongolian Wulanbuhe and Kubuqi deserts are the main provenances of the coarse sediment in the desert channel of the Yellow River. Due to the higher fluidity of the fine sediment, they are mainly contributed by the local sediment sources and the tributaries that originated from the loess area of the upper reach of the Yellow River.

  3. Dramatic Demand Reduction In The Desert Southwest

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert [Univ. of Nevada, Las Vegas, NV (United States); Hsieh, Sean [Univ. of Nevada, Las Vegas, NV (United States); Lee, Joon [Univ. of Nevada, Las Vegas, NV (United States); Baghzouz, Yahia [Univ. of Nevada, Las Vegas, NV (United States); Cross, Andrew [Univ. of Nevada, Las Vegas, NV (United States); Chatterjee, Sarah [NV Energy, Las Vegas, NV (United States)

    2015-07-06

    This report summarizes a project that was funded to the University of Nevada Las Vegas (UNLV), with subcontractors Pulte Homes and NV Energy. The project was motivated by the fact that locations in the Desert Southwest portion of the US demonstrate very high peak electrical demands, typically in the late afternoons in the summer. These high demands often require high priced power to supply the needs, and the large loads can cause grid supply problems. An approach was proposed through this contact that would reduce the peak electrical demands to an anticipated 65% of what code-built houses of the similar size would have. It was proposed to achieve energy reduction through four approaches applied to a development of 185 homes in northwest part of Las Vegas named Villa Trieste. First, the homes would all be highly energy efficient. Secondly, each house would have a PV array installed on it. Third, an advanced demand response technique would be developed to allow the resident to have some control over the energy used. Finally, some type of battery storage would be used in the project. Pulte Homes designed the houses. The company considered initial cost vs. long-term savings and chose options that had relatively short paybacks. HERS (Home Energy Rating Service) ratings for the homes are approximately 43 on this scale. On this scale, code-built homes rate at 100, zero energy homes rate a 0, and Energy Star homes are 85. In addition a 1.764 Wp (peak Watt) rated PV array was used on each house. This was made up of solar shakes that were in visual harmony with the roofing material used. A demand response tool was developed to control the amount of electricity used during times of peak demand. While demand response techniques have been used in the utility industry for some time, this particular approach is designed to allow the customer to decide the degree of participation in the response activity. The temperature change in the residence can be decided by the residents by

  4. Ecological restoration of southwestern ponderosa pine ecosystems: A broad perspective

    Science.gov (United States)

    Allen, Craig D.; Savage, Melissa; Falk, Donald A.; Suckling, Kieran F.; Swetnam, Thomas W.; Schulke, Todd; Stacey, Peter B.; Morgan, Penelope; Hoffman, Martos; Klingel, Jon T.

    2002-01-01

    The purpose of this paper is to promote a broad and flexible perspective on ecological restoration of Southwestern (U.S.) ponderosa pine forests. Ponderosa pine forests in the region have been radically altered by Euro-American land uses, including livestock grazing, fire suppression, and logging. Dense thickets of young trees now abound, old-growth and biodiversity have declined, and human and ecological communities are increasingly vulnerable to destructive crown fires. A consensus has emerged that it is urgent to restore more natural conditions to these forests. Efforts to restore Southwestern forests will require extensive projects employing varying combinations of young-tree thinning and reintroduction of low-intensity fires. Treatments must be flexible enough to recognize and accommodate: high levels of natural heterogeneity; dynamic ecosystems; wildlife and other biodiversity considerations; scientific uncertainty; and the challenges of on-the-ground implementation. Ecological restoration should reset ecosystem trends toward an envelope of “natural variability,” including the reestablishment of natural processes. Reconstructed historic reference conditions are best used as general guides rather than rigid restoration prescriptions. In the long term, the best way to align forest conditions to track ongoing climate changes is to restore fire, which naturally correlates with current climate. Some stands need substantial structural manipulation (thinning) before fire can safely be reintroduced. In other areas, such as large wilderness and roadless areas, fire alone may suffice as the main tool of ecological restoration, recreating the natural interaction of structure and process. Impatience, overreaction to crown fire risks, extractive economics, or hubris could lead to widespread application of highly intrusive treatments that may further damage forest ecosystems. Investments in research and monitoring of restoration treatments are essential to refine

  5. Determining the resilience of carbon dynamics in semi-arid biomes of the Southwestern US to severe drought and altered rainfall patterns

    Science.gov (United States)

    Litvak, M. E.; Krofcheck, D. J.; Hilton, T. W.; Fox, A. M.; Osuna, J. L.

    2011-12-01

    Water is critically important for biotic processes in semi-arid ecosystems and 2011 is developing as one of the most severe drought years on record for many parts of the Southwestern US. To quantify the impact of this severe drought on regional carbon and energy balance, we need a more detailed understanding of how water limitation alters ecosystem processes across a range of semi-arid biomes. We quantified the impact of severe drought and changes in both the quantity and distribution of precipitation on ecosystem biotic structure and function across the range of biomes represented in the NM elevation gradient network (desert grassland, creosote shrubland, juniper savanna, piñon-juniper woodland, ponderosa pine forest and subalpine mixed conifer forest). We compared how daily, seasonal and annual carbon and energy balance and their components in each of these biomes respond to changes in rainfall patterns using continuous measurements of carbon, water and energy exchange and associated measurements in each of these biomes during a 5 year period (2006-2011) that included a severe drought, and large variability in both winter precipitation and the timing and intensity of the monsoon. To understand the underlying mechanisms, we used time series of radiation absorbed by vegetation, surface albedo, soil moisture storage, phenology, gross primary productivity (GPP), ecosystem respiration (Re), and WorldView-2 images acquired pre- and post-monsoon in each of these biomes. In all of the biomes except the desert grassland site, the strength and timing of both winter and monsoon precipitation are important controls over carbon and energy dynamics in this region, though we see site-specific sensitivities across the elevation gradient. Over the past 5 years, carbon dynamics in the desert grassland site appears to be decoupled from winter precipitation. In addition, carbon dynamics in disturbed grassland and pinon-juniper ecosystems were more sensitive to severe drought than

  6. An Integrated Multi-Sensor Approach to Monitor Desert Environments by UAV and Satellite Sensors: Case Study Kubuqi Desert, China

    Science.gov (United States)

    Kim, J.; Lin, C. W.; vanGasselt, S.; Lin, S.; Lan, C. W.

    2017-12-01

    Expanding deserts have been causing significant socio-economical threats by, e.g., hampering anthropogenic activities or causing decline of agricultural productivity. Countries in the Asian-Pacific regions in particular have been suffering from dust storms originating in the arid deserts of China, Mongolia and central Asia. In order to mitigate such environmental interferences by means of, e.g. combat desertification activities and early warning systems, the establishment of reliable desert monitoring schemes is needed. In this study, we report on a remote sensing data fusion approach to constantly and precisely monitor desert environments. We have applied this approach over a test site located in the Kubuqi desert located in Northeast China and which is considered to be a major contributor of dust storms today. In order to understand spatial and temporal trends of desertification, the planimetric distribution and 3D shape and size of sand dunes were reconstructed using Digital Terrain Models (DTM) derived from stereo observations made by Unmanned Aerial Vehicles (UAV). Based on this, the volumetric change of sand dunes was directly estimated through co-registered DTMs. We furthermore derived and investigated topographic parameters, such as the aerodynamic roughness length, the protrusion coefficient, the Normalized Difference Angular Index, and the phase coherence derived from spaceborne optical/synthetic aperture radar (SAR) remote sensing assets with the calibration index from UAV observation. Throughout such a multi-data approach, temporal changes of a target's environmental parameters can be traced, analyzed and correlated with weather conditions. An improved understanding of aeolian processes in sand deserts will be a valuable contribution for desertification combat activities and early warning systems for dust storm generation. Future research needs to be conducted over more extensive spatial and temporal domains, also by combining investigations on the

  7. Reference intervals and physiologic alterations in hematologic and biochemical values of free-ranging desert tortoises in the Mojave Desert

    Science.gov (United States)

    Christopher, Mary M.; Berry, Kristin H.; Wallis, I.R.; Nagy, K.A.; Henen, B.T.; Peterson, C.C.

    1999-01-01

    Desert tortoise (Gopherus agassizii) populations have experienced precipitous declines resulting from the cumulative impact of habitat loss, and human and disease-related mortality. Evaluation of hematologic and biochemical responses of desert tortoises to physiologic and environmental factors can facilitate the assessment of stress and disease in tortoises and contribute to management decisions and population recovery. The goal of this study was to obtain and analyze clinical laboratory data from free-ranging desert tortoises at three sites in the Mojave Desert (California, USA) between October 1990 and October 1995, to establish reference intervals, and to develop guidelines for the interpretation of laboratory data under a variety of environmental and physiologic conditions. Body weight, carapace length, and venous blood samples for a complete blood count and clinical chemistry profile were obtained from 98 clinically healthy adult desert tortoises of both sexes at the Desert Tortoise Research Natural area (western Mojave), Goffs (eastern Mojave) and Ivanpah Valley (northeastern Mojave). Samples were obtained four times per year, in winter (February/March), spring (May/June), summer (July/August), and fall (October). Years of near-, above- and below-average rainfall were represented in the 5 yr period. Minimum, maximum and median values, and central 95 percentiles were used as reference intervals and measures of central tendency for tortoises at each site and/or season. Data were analyzed using repeated measures analysis of variance for significant (P < 0.01) variation on the basis of sex, site, season, and interactions between these variables. Significant sex differences were observed for packed cell volume, hemoglobin concentration, aspartate transaminase activity, and cholesterol, triglyceride, calcium, and phosphorus concentrations. Marked seasonal variation was observed in most parameters in conjunction with reproductive cycle, hibernation, or seasonal

  8. DESERT ECOSYSTEMS: MAPPING, MONITORING & ASSESSMENT USING SATELLITE REMOTE SENSING

    Directory of Open Access Journals (Sweden)

    A. S. Arya

    2012-09-01

    Full Text Available Desert ecosystems are unique but fragile ecosystems , mostly vulnerable to a variety of degradational processes like water erosion, vegetal degradation, salinity, wind erosion , water logging etc. Some researchers consider desertification to be a process of change, while others view it as the end result of a process of change. There is an urgent need to arrest the process of desertification and combat land degradation. Under the auspices of the United Nations Convention to Combat Desertification (UNCCD, Space Applications Centre, Ahmedabad has undertaken the task of mapping, monitoring and assessment of desertification carrying out pilot project in hot and cold desert regions in drylands on 1:50,000 scale followed by systematic Desertification Status Mappaing (DSM of India on 1:500,000 scale.

  9. The Plant Genetic Engineering Laboratory For Desert Adaptation

    Science.gov (United States)

    Kemp, John D.; Phillips, Gregory C.

    1985-11-01

    The Plant Genetic Engineering Laboratory for Desert Adaptation (PGEL) is one of five Centers of Technical Excellence established as a part of the state of New Mexico's Rio Grande Research Corridor (RGRC). The scientific mission of PGEL is to bring innovative advances in plant biotechnology to bear on agricultural productivity in arid and semi-arid regions. Research activities focus on molecular and cellular genetics technology development in model systems, but also include stress physiology investigations and development of desert plant resources. PGEL interacts with the Los Alamos National Laboratory (LANL), a national laboratory participating in the RGRC. PGEL also has an economic development mission, which is being pursued through technology transfer activities to private companies and public agencies.

  10. Relative abundance of desert tortoises on the Nevada Test Site

    International Nuclear Information System (INIS)

    Rautenstrauch, K.R.; O'Farrell, T.P.

    1993-01-01

    Seven hundred fifty-nine transects having a total length of 1,191 km were walked during 1981--1986 to determine the distribution and relative abundance of desert tortoises (Gopherus agassizii) on the Nevada Test Site (NTS). The abundance of tortoises on NTS was low to very low relative to other populations in the Mojave Desert. Sign of tortoises was found from 880 to 1,570 m elevation and was more abundant above 1,200 m than has been reported previously for Nevada. Tortoises were more abundant on NTS on the upper alluvial fans and slopes of mountains than in valley bottoms. They also were more common on or near limestone and dolomite mountains than on mountains of volcanic origin

  11. Who Needs Religion When You Have The Desert?

    DEFF Research Database (Denmark)

    Sørensen, Bent

    In my paper I propose to read so-called ‘post-ironic’ texts by authors associated with the Blank Generation and Generation X (including Bret Easton Ellis and Douglas Coupland, as well as less well-known authors such as K.S. Haddock) and examine their use of the desert as a trope for identity...... testing and summation. Perhaps surprisingly, one finds in novels such as Ellis’ Less Than Zero (1984) and Coupland’s Generation X (1991) a reliance on desert locations to provide an alternative to the numerous non-places (in Marc Augé’s sense of the term) that otherwise make up the setting of these works....

  12. Biotechnological Applications Derived from Microorganisms of the Atacama Desert

    Directory of Open Access Journals (Sweden)

    Armando Azua-Bustos

    2014-01-01

    Full Text Available The Atacama Desert in Chile is well known for being the driest and oldest desert on Earth. For these same reasons, it is also considered a good analog model of the planet Mars. Only a few decades ago, it was thought that this was a sterile place, but in the past years fascinating adaptations have been reported in the members of the three domains of life: low water availability, high UV radiation, high salinity, and other environmental stresses. However, the biotechnological applications derived from the basic understanding and characterization of these species, with the notable exception of copper bioleaching, are still in its infancy, thus offering an immense potential for future development.

  13. Ancient photosynthetic eukaryote biofilms in an Atacama Desert coastal cave

    Science.gov (United States)

    Azua-Bustos, A.; Gonzalez-Silva, C.; Mancilla, R.A.; Salas, L.; Palma, R.E.; Wynne, J.J.; McKay, C.P.; Vicuna, R.

    2009-01-01

    Caves offer a stable and protected environment from harsh and changing outside prevailing conditions. Hence, they represent an interesting habitat for studying life in extreme environments. Here, we report the presence of a member of the ancient eukaryote red algae Cyanidium group in a coastal cave of the hyperarid Atacama Desert. This microorganism was found to form a seemingly monospecific biofilm growing under extremely low photon flux levels. Our work suggests that this species, Cyanidium sp. Atacama, is a new member of a recently proposed novel monophyletic lineage of mesophilic "cave" Cyanidium sp., distinct from the remaining three other lineages which are all thermo-acidophilic. The cave described in this work may represent an evolutionary island for life in the midst of the Atacama Desert. ?? Springer Science + Business Media, LLC 2009.

  14. Field Performance of Photovoltaic Systems in the Tucson Desert

    Science.gov (United States)

    Orsburn, Sean; Brooks, Adria; Cormode, Daniel; Greenberg, James; Hardesty, Garrett; Lonij, Vincent; Salhab, Anas; St. Germaine, Tyler; Torres, Gabe; Cronin, Alexander

    2011-10-01

    At the Tucson Electric Power (TEP) solar test yard, over 20 different grid-connected photovoltaic (PV) systems are being tested. The goal at the TEP solar test yard is to measure and model real-world performance of PV systems and to benchmark new technologies such as holographic concentrators. By studying voltage and current produced by the PV systems as a function of incident irradiance, and module temperature, we can compare our measurements of field-performance (in a harsh desert environment) to manufacturer specifications (determined under laboratory conditions). In order to measure high-voltage and high-current signals, we designed and built reliable, accurate sensors that can handle extreme desert temperatures. We will present several benchmarks of sensors in a controlled environment, including shunt resistors and Hall-effect current sensors, to determine temperature drift and accuracy. Finally we will present preliminary field measurements of PV performance for several different PV technologies.

  15. Holocene RSL variation on southwestern Disko Island (Greenland)

    DEFF Research Database (Denmark)

    Emerich Souza, Priscila; Nielsen, Lars; Kroon, Aart

    We investigate RSL variations during the Holocene in Lakse Bugt by assessing topography, internal structure, and luminescence ages of fossil beach ridges and the modern beach. Lakse Bugt (Bay) lies on the southwestern coast of Disko Island in a mesotidal regime and a mild wave climate. Beach ridges...... are widespread over the marine terrace, extending from ~40 above sea level (m asl). The most recent ridges terminate either at the beach or at the coastal sandy cliffs ~8 m asl immediately behind the modern beach. These ridges are covered mainly by rounded boulders; the terrain surfaces of the swales have...... clearly been deformed by freezing and thawing processes, in contrast to those of the ridge crests, which are relatively smooth. High-resolution reflection GPR data and high resolution topographical data were collected along cross-shore transects using a shielded 250 MHz antennae system and a DGPS system...

  16. Macrofungi in the lateritic scrub jungles of southwestern India

    Directory of Open Access Journals (Sweden)

    A. A. Greeshma

    2015-09-01

    Full Text Available A pilot study on macrofungi in scrub jungles (with and without fire-impact in lateritic region of southwestern coast of India was carried out.  Out of 11 species in 10 genera recovered, six and five species were confined to scrub jungle and fire-impacted scrub jungle, respectively.  An ectomycorrhizal Amanita sp. was the most frequent in scrub jungle associated with exotic (Acacia auriculiformis and A. mangium and plantation (Anacardium occidentale trees.  Based on traditional knowledge, it is a highly edible and nutritional delicacy in the coastal regions.  Astraeus odoratus was another common ectomycorrhizal fungus in native trees Hopea ponga, which was recovered from the fire-impacted scrub jungle and is possibly edible.  Edible termite mound mushroom Termitomyces striatus was also common in the fire-impacted scrub jungle.  Chlorophyllum molybdites was the most frequent mushroom in the fire-impacted scrub jungle.  

  17. Uranium favorability of southwestern Oklahoma and north-central Texas

    International Nuclear Information System (INIS)

    Stanton, G.D.; Brogdon, L.D.; Quick, J.V.; Thomas, N.G.; Martin, T.S.

    1977-10-01

    Results are presented of a project to identify and delineate units and (or) facies that are favorable for uranium in the Upper Pennsylvanian and Lower Permian strata of north-central Texas and southwestern Oklahoma. To aid in this evaluation, an assessment of the probable uranium rocks (Wichita and Arbuckle Mountains) was necessary. Surface samples were collected from igneous and sedimentary rocks. Stream-sediment samples were also collected. However, the main emphasis of the investigation of the sedimentary units was on the identification of sedimentary facies trends in the subsurface and an evaluation of the uranium favorability within units studied. The area investigated centers along the Red River, the boundary between Texas and Oklahoma. The project area encompasses approximately 17,000 sq. mi. It includes all or parts of Cooke, Montague, Clay, Wichita, Wilbarger, Hardeman, Baylor, Knox, and Archer Counties in Texas and Love, Jefferson, Cotton, Tillman, Jackson, Stephens, Carter, Comanche, Harmon, and Greer Counties in Oklahoma

  18. Lithospheric Strength Beneath the Zagros Mountains of Southwestern Iran

    Science.gov (United States)

    Adams, A. N.; Nyblade, A.; Brazier, R.; Rodgers, A.; Al-Amri, A.

    2006-05-01

    The Zagros Mountain Belt of southwestern Iran is among the most seismically active mountain belts in the world. Early seismic studies of this area found that the lithosphere underlying the Zagros Mountains follows the "jelly sandwich" model, having a strong upper crust and a strong lithospheric mantle, separated by a weak lower crust. More recent studies, which analyzed earthquakes originating within the Zagros Mountains that were recorded at teleseismic distances, however, found that these earthquakes occurred only within the upper crust, thus indicating that the strength of the Zagros Mountains' lithosphere lies only within the upper crust, in accordance with the "creme brulee" lithospheric model. Preliminary analysis of regionally recorded earthquakes that originated within the Zagros Mountains is presented here. Using earthquakes recorded at regional distances will allow the analysis of a larger dataset than has been used in previous studies. Preliminary results show earthquakes occurring throughout the crust and possibly extending into the upper mantle.

  19. Surficial geologic map of the Dillingham quadrangle, southwestern Alaska

    Science.gov (United States)

    Wilson, Frederic H.

    2018-05-14

    The geologic map of the Dillingham quadrangle in southwestern Alaska shows surficial unconsolidated deposits, many of which are alluvial or glacial in nature. The map area, part of Alaska that was largely not glaciated during the late Wisconsin glaciation, has a long history reflecting local and more distant glaciations. Late Wisconsin glacial deposits have limited extent in the eastern part of the quadrangle, but are quite extensive in the western part of the quadrangle. This map and accompanying digital files are the result of the interpretation of black and white aerial photographs from the 1950s as well as more modern imagery. Limited new field mapping in the area was conducted as part of a bedrock mapping project in the northeastern part of the quadrangle; however, extensive aerial photographic interpretation represents the bulk of the mapping effort.

  20. Guanophilic fungi in three caves of southwestern Puerto Rico

    Directory of Open Access Journals (Sweden)

    Nieves-Rivera Angel M.

    2009-01-01

    Full Text Available Fifty species of guanophilic (bat guano-loving fungi were isolated from field-collected samples within three caves in southwesternPuerto Rico; most were mitosporic fungi (23 species. The caves studied were Cueva La Tuna (Cabo Rojo, Cueva de Malano(Sistema de Los Chorros, San Germán, and Cueva Viento (El Convento Cave-Spring System, Guayanilla-Peñuelas. The mostconspicuous fungus by far was the zygomycete Circinella umbellata (Mucorales. Circinella umbellata dominated the bat guanoincubation chambers (Petri dishes lined with sterile filter paper moistened with sterile water at ambient laboratory conditions.Nineteen species of basidiomycetes (e.g., Ganoderma cf. resinaceum, Geastrum cf. minimum, Lepiota sp., Polyporus sp., Ramariasp. and three species of ascomycetes (Hypoxylon sp., Xylaria anisopleura, and X. kegeliana were also recorded. They were foundon soil, rotting leaves, bark and rotting wood, buried in bat guano located below natural skylights or sinkholes.

  1. LEXICOGRAPHICAL STUDIES ON THE SOUTHWESTERN DIALECTS OF THE UKRAINIAN LANGUAGE

    Directory of Open Access Journals (Sweden)

    Vasyl Greshchuk

    2015-05-01

    Full Text Available The paper deals with the issue of compiling the Southwestern dialect dictionaries. A survey of the history of the dialect dictionaries from the mid-nineteenth century to the present is given. The scientific background and principles of compiling the dictionaries in question are analyzed. Special attention is given to dictionary register, dictionary entry structure, description of semantic properties of registered words, illustrative material, word passport. It has been established that many aspects of the Hutsul dialects are reflected in different lexicographical works, though a big academic dictionary still needs to be written. There exist big differential dictionaries of the Boyko, Bukovynian, Upper Dniestrian dialects. The Transcarpathian and Lemko dialects are less closely studied in this respect. There have been carried out some lexicographical studies of the Podillian, Pokuttian, Southern Volynian dialects and the dialects of the Sian river basin; further research is certainly needed to provide a firm basis for compiling dictionaries of these dialects.

  2. Paleozoic stratigraphy of two areas in southwestern Indiana

    International Nuclear Information System (INIS)

    Droste, J.B.

    1976-09-01

    Two areas recommended for evaluation as solid waste disposal sites lie along the strike of Paleozoic rocks in southwestern Indiana. Thin Pennsylvanian rocks and rocks of the upper Mississippian are at the bedrock surface in maturely dissected uplands in both areas. The gross subsurface stratigraphy beneath both areas is the same, but facies and thickness variation in some of the subsurface Paleozoic units provide for some minor differences between the areas. Thick middle Mississippi carbonates grade downward into clastics of lower Mississippian (Borden Group) and upper Devonian (New Albany Shale) rocks. Middle Devonian and Silurian rocks are dominated by carbonate lithologies. Upper Ordovician (Maquoketa Group) overly carbonates of middle Ordovician age. Thick siltstone and shale of the Borden Group-New Albany Shale zone and Maquoketa Group rocks should be suitable for repository development

  3. Feasibility study of wind-generated electricity for rural applications in southwestern Ohio

    Science.gov (United States)

    Kohring, G. W.

    The parameters associated with domestic production of wind generated electricity for direct use by small farms and rural homes in the southwestern Ohio region are discussed. The project involves direct utility interfaced electricity generation from a horizontal axis, down-wind, fixed pitch, wind powered induction generator system. Goals of the project are to determine: the ability to produce useful amounts of domestic wind generated electricity in the southwestern Ohio region; economic justification for domestic wind generated electrical production; and the potential of domestic wind generated electricity for reducing dependence on non-renewable energy resources in the southwestern Ohio region.

  4. Molecular mechanisms of foliar water uptake in a desert tree

    OpenAIRE

    Yan, Xia; Zhou, Maoxian; Dong, Xicun; Zou, Songbing; Xiao, Honglang; Ma, Xiao-Fei

    2015-01-01

    Water deficits severely affect growth, particularly for the plants in arid and semiarid regions of the world. In addition to precipitation, other subsidiary water, such as dew, fog, clouds and small rain showers, may also be absorbed by leaves in a process known as foliar water uptake. With the severe scarcity of water in desert regions, this process is increasingly becoming a necessity. Studies have reported on physical and physiological processes of foliar water uptake. However, the molecul...

  5. Desert Wadis and Smoke from Kuwait Oil Fires, Saudi Arabia

    Science.gov (United States)

    1991-01-01

    Smoke from the Kuwait Oil Fires obscures the view of the desert wadis, Saudi Arabia (29.5N, 42.5E). During the brief Gulf war between Iraq and the Allied forces, many of the oil wells in Kuwait were destroyed and set afire. For several months, those fires burned out of control, spewing smoke and ash for hundreds of miles in many directions depending on the altitude, time of year and the prevailing winds.

  6. The Mystery of the Gun Turret in the Desert

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, R. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-11-30

    The mystery of the gun turret in the desert began with an ingenious idea: to develop a reusable open-air line of sight diagnostic device to support LLNL’s early nuclear weapons development efforts. Obtained from the Mare Island Navy Shipyard (MINS) in January 1957, the gun turret traveled by ship to the Naval Construction Battalion base at Port Hueneme, California, and then by truck to Area 2 in the Yucca Flats valley at the Nevada Nuclear Security Site (NNSS).

  7. Precipitation Dynamics and Feedback mechanisms of the Arabian Desert

    Science.gov (United States)

    Burger, Roelof; Kucera, Paul; Piketh, Stuart; Axisa, Duncan; Chapman, Michael; Krauss, Terry; Ghulam, Ayman

    2010-05-01

    The subtropical Arabian desert extends across the entire Peninsula. The Arabian desert finds itself in the downward branch of the Hadley cell with persistent subsidence. This stabilizes the atmosphere and lowers the relative humidity. The result is a strongly capped convective boundary layer and an extremely dry mid troposphere. Most of the area experience very little rainfall, generally below 100 mm per year, resulting in the largest uninterrupted sand desert in the world. However, local factors such as an unbroken 1000 km escarpment along the Red Sea, rocky mountains between 2000 and 3000 m, and gravel plains cut by wadis, causes micro climates with significant altered precipitation characteristics. Altitude oases with annual rainfall between 200 mm and 500 mm are found on the Asir mountains in the south west and over the Jebel Akdhar mountains on the Gulf coast of Oman. This region receives most of its rainfall in the Northern Hemisphere summer driven by a monsoon trough and the ITCZ. During summer, moist surface winds from the Red Sea converges with dry easterlies triggering convection along the Asir escarpment on a daily basis. Clear mornings grow into a layer of Altocumulus stratiformis cumulogenites by noon, which usually last until sunset. This cloud deck interacts with large severe convective cells which grow to the top of the troposphere by mid afternoon. The north experience a mediterranean climate with eastward propagating midlatitude cyclones causing wintertime rainfall. Characteristic cloud bands form over the northern interior. Vertically layered embedded convective cells that are not coupled with the surface propagate on north easterly tracks. This result in another oasis with annual rainfall exceeding 200 mm. Surface based convection causes isolated thunderstorms during spring and early summer, but cloud bases increase as the season progress until the evaporating downdraft causes dust storms. In-situ measurements, WRF model runs, radiosonde ascends

  8. Ground-water quality and geochemistry, Carson Desert, western Nevada

    Science.gov (United States)

    Lico, Michael S.; Seiler, R.L.

    1994-01-01

    Aquifers in the Carson Desert are the primary source of drinking water, which is highly variable in chemical composition. In the shallow basin-fill aquifers, water chemistyr varies from a dilute calcium bicarbonate-dominated water beneath the irrigated areas to a saline sodium chloride- dominated water beneath unirrigated areas. Water samples from the shallow aquifers commonly have dissolved solids, chloride, magnesium, sulfate, arsenic, and manganese concentrations that exceed State of Nevada drinking-water standards. Water in the intermediante basin-fill aquifers is a dilute sodium bicarbonate type in the Fallon area and a distinctly more saline sodium chloride type in the Soda Lake-Upsal Hogback area. Dissolved solids, chloride, arsenic, fluoride, and manganese concen- trations commonly exceed drinking-water standards. The basalt aquifer contains a dilute sodium bicarbonate chloride water. Arsenic concentrations exceed standards in all sampled wells. The concen- trations of major constituents in ground water beneath the southern Carson Desert are the result of evapotranspiration and natural geochemical reactions with minerals derived mostly from igneous rocks. Water with higher concentrations of iron and manganese is near thermodynamic equilibrium with siderite and rhodochrosite and indicates that these elements may be limited by the solubility of their respective carbonate minerals. Naturally occurring radionuclides (uranium and radon-222) are present in ground water from the Carson Desert in concen- tratons higher than proposed drinking-water standards. High uranium concentrations in the shallow aquifers may be caused by evaporative concentration and the release of uranium during dissolution of iron and manganese oxides or the oxidation of sedimentary organic matter that typically has elevated uranium concentrations. Ground water in the Carson Desert does not appear to have be contaminated by synthetic organic chemicals.

  9. Chromophoric Dissolved Organic Matter in Southwestern Greenland Lakes

    Science.gov (United States)

    Osburn, C. L.; Giles, M. E.; Underwood, G. J. C.

    2014-12-01

    Dissolved organic matter (DOM) is an important property of Arctic lake ecosystems, originating from allochthonous inputs from catchments and autochthonous production by plankton in the water column. Little is known about the quality of DOM in Arctic lakes that lack substantial inputs from catchments and such lakes are abundant in southwestern Greenland. Colored dissolved organic matter (CDOM), the fraction that absorbs ultraviolet (UV) and visible light, is the controlling factor for the optical properties of many surface waters and as well informs on the quality of DOM. We examined the quality of CDOM in 21 lakes in southwestern Greenland, from the ice sheet to the coast, as part of a larger study examining the role of DOM in regulating microbial communities in these lakes. DOM was size fractioned and absorbance and fluorescence was measured on each size fraction, as well as on bulk DOM. The specific ultraviolet absorbance (SUVA) at 254 nm (SUVA254), computed by normalizing absorption (a254) to dissolved organic carbon (DOC) concentration, provided an estimate of the aromatic carbon content of DOM. SUVA values were generally CDOM fluorescence was used to determine the relative abundance of allochthonous and autochthonous DOM in all size fractions. Younger lakes near the ice sheet and lakes near the coast had lower amounts of CDOM and appeared more microbial in quality. However, lakes centrally located between the ice sheet and the coast had the highest CDOM concentrations and exhibited strong humic fluorescence. Overall distinct differences in CDOM quality were observed between lake locations and among DOM size fractions.

  10. [Giant-cell arteritis: a descriptive study in southwestern Spain].

    Science.gov (United States)

    Calvo Romero, J M; Magro Ledesma, D; Ramos Salado, J L; Bureo Dacal, J C; de Dios Arrebola García, J; Bureo Dacal, P; Pérez Miranda, M

    2000-02-01

    To study the clinical and laboratory features of a series of patients with giant cell arteritis (GCA) or temporal arteritis in south-western Spain (Extremadura). Retrospective study of 25 patients with GCA diagnosed by temporal artery biopsy between 1990 and 1998. Nine patients were males and 16 (64%) females. Sixteen cases (64%) presented polymyalgia rheumatica (PMR). Other clinical findings were: fever/febricula (64%), constitutional syndrome (64%), new headache (96%), visual symptoms (48%), jaw claudication (17%) and abnormal temporal arteries (17%). All patients had an ESR of more than 50 mm/hour and a raised C-reactive protein. Thirteen patients (52%) had anemia (hemoglobin level < 12 g/dl). Eleven cases (44%) presented a platelet count higher than 400,000/mm3. Four patients (16%) had an elevated AST and/or ALT levels and 8 patients (32%) had an elevated GGT and/or alkaline phosphatase levels. In patients with PMR, there was a higher frequency of constitutional syndrome (81 vs 33%, p = 0.02). In females, there was a higher frequency of anemia (75 vs 11%, p < 0.01), platelet count higher than 400,000/mm3 (75 vs 0%, p < 0.01) and elevated AST and/or ALT (25 vs 0%, p < 0.01) and elevated GGT and/or alkaline phosphatase (50 vs 0%, p < 0.01) levels. The clinical and laboratory features of GCA in our series of patients in south-western Spain are similar to that described in other spanish populations, with the exception of a slightly higher frequency of PMR and a lower frequency of jaw claudication and abnormal temporal arteries. In our study, the clinical picture of GCA was more severe in patients with PMR and in females.

  11. Towards a delimitation of southwestern Nigeria into hydrological regions

    Science.gov (United States)

    Ogunkoya, O. O.

    1988-05-01

    Fifteen third-order drainage basins (1:50,000) on the Basement Complex rocks of southwestern Nigeria are classified into hydrological regions using hydrologic response parameters of average daily mean specific discharge ( QA); daily mean specific discharges equalled or exceeded 90% ( Q90), 50% ( Q50) and 10% ( Q10) of the study period; variability index of flow ( VI); recession constant ( K) of flow from peak discharge at the end of the rainy season to minimum discharge in the dry season; total annual runoff ( RO); total runoff within the dry season ( DSRO); dry season runoff as a percentage of total annual runoff (% DSRO); runoff coefficient ( ROC); and, number of days during the study period when there was no flow ( NFD). An ordination technique and a classification algorithm derived from cluster analysis technique and incorporating the analysis of variance (ANOVA) tests to determine the level of significance of the homogeneity of derived classes, were used to classify the fifteen basins into five hydrologically homogeneous regions. The constituent basins of each region were observed to share common basin geology. It was observed that those drainage basins having at least 50% of their basin area underlain by quartzitic rocks form two groups and have the most desirable or optimal hydrologic response patterns, desirability or optimality being in terms of ability to potentially meet water resource development requirements (i.e. high perennial discharge, low variability and large groundwater contribution to stream flow). The basins predominantly underlain by granite-gneisses and amphibolitic rocks have much poorer hydrologic response patterns. Hydrological regionalization in southwestern Nigeria appears to be influenced by drainage basin geology while percentage area of the basin underlain by massive quartzites could be used as an index of occurrence of desirable hydrologic response pattern.

  12. The evolution of deserts with climatic changes in China since 150 ka B.P.

    Institute of Scientific and Technical Information of China (English)

    董光荣; 陈惠忠; 王贵勇; 李孝泽; 邵亚军; 金炯

    1997-01-01

    According to the bioclimatic zones, dune mobility and the fabric characteristics of stratigraphic sedimentary facies, the deserts in China are divided into Eastern, Western, Central and Northwestern deserts. Based on the records of stratigraphical facies, climatic proxies, historical data, etc. in each desert region, the evolution of deserts with climatic changes in time and space since 150 ka B. P. in China are dealt with; then the evolution of deserts in relation to the glacial climatic fluctuations caused by solar radiation changes, underlying surface variation and their feedback mechanism is discussed through comparison with global records; finally, in consideration of global wanning due to increasing of greenhouse gases such as CO2, the possible tendency of the evolution of deserts and the climatic changes is discussed.

  13. Urban "accidental" wetlands mediate water quality and heat exposure for homeless populations in a desert city

    Science.gov (United States)

    Palta, M.

    2015-12-01

    In urban settings where humans interact in complex ways with ecosystems, there may be hidden or unanticipated benefits (services) or harm (disservices) conferred by the built environment. We examined interactions of a highly vulnerable population, the homeless, with urban waterways and wetlands in the desert city of Phoenix, Arizona, U.S.A. Climate change models project increases in heat, droughts, and extreme floods for the southwestern U.S. These projected changes pose a number of problems for sustainability and quality of future water supply, and the ability of human populations to mitigate heat stress and avoid fatalities. Urban wetlands that are created "accidentally" (by water pooling in abandoned areas of the landscape) have many structural (e.g., soils and hydrology) and functional (e.g., high denitrification) elements that mimic natural, unaltered aquatic systems. Accidental wetland systems in the dry bed of the Salt River, fed by storm and waste water from urban Phoenix, are located within economically depressed sections of the city, and show the potential for pollutant and heat mitigation. We used a mixed-method socio-ecological approach to examine wetland ecosystem functions and the ways in which homeless populations utilize Salt River wetlands for ecosystem services. Interviews and trash surveys indicated that homeless people are accessing and utilizing the wetlands as a source of running water, for sanitary and heat mitigation services, and for recreation and habitation. Environmental monitoring demonstrated that the wetlands can provide a reliable source of running water, nutrient and pathogen removal, heat mitigation, and privacy, but they may also pose a health risk to individuals coming in contact with the water through drinking or bathing. Whether wetlands provided a net benefit vs. harm varied according to site, season, and particular service, and several tradeoffs were identified. For example, heat is highest during the summer storm season

  14. Plantation of desert and renewal of earth with small LMRs

    International Nuclear Information System (INIS)

    Hattori, Sadao; Minato, Akio; Handa, Norihiko; Hashizume, Kenichi.

    1991-01-01

    Desertification is advancing at rapid rate on the earth. The technical development for preventing the desertification has been requested for advanced countries. Particularly in the southern hemisphere, the energy which can restore green in deserts and supply the electric power required for living is necessary. In this paper, the supply of electric power using the small fast reactors which are excellent in the safety and maintainability and the desalting plants required for tree planting in deserts, and further, the regeneration of the earth accompanying it, are discussed. By desertification, yearly 6 million ha of lands are devastated to unrecoverable extent, and those concentrate in the districts where yearly rainfall is little. In order to prevent desertification, it is necessary to stabilize surface soil by tree planting. Further, in order to prevent the deforestation for obtaining energy, the dual purpose plants for power generation and desalting are important. In this paper, the concept of obtaining water resources from sea, carrying out the desalting, supplying the water to the forefront of deserts and forming green belts there by using fast reactors is considered. The present status of desertification, the desalting of seawater by nuclear power, small fast reactors aiming at ultra-safety, the production of green, and the regeneration of the earth are described. (K.I.)

  15. Colonization patterns of soil microbial communities in the Atacama Desert.

    Science.gov (United States)

    Crits-Christoph, Alexander; Robinson, Courtney K; Barnum, Tyler; Fricke, W Florian; Davila, Alfonso F; Jedynak, Bruno; McKay, Christopher P; Diruggiero, Jocelyne

    2013-11-20

    The Atacama Desert is one of the driest deserts in the world and its soil, with extremely low moisture, organic carbon content, and oxidizing conditions, is considered to be at the dry limit for life. Analyses of high throughput DNA sequence data revealed that bacterial communities from six geographic locations in the hyper-arid core and along a North-South moisture gradient were structurally and phylogenetically distinct (ANOVA test for observed operating taxonomic units at 97% similarity (OTU0.03), P microbial communities' diversity metrics (least squares linear regression for observed OTU0.03 and air RH and soil conductivity, P PCoA Spearman's correlation for air RH and soil conductivity, P <0.0001), indicating that water availability and salt content are key factors in shaping the Atacama soil microbiome. Mineralization studies showed communities actively metabolizing in all soil samples, with increased rates in soils from the southern locations. Our results suggest that microorganisms in the driest soils of the Atacama Desert are in a state of stasis for most of the time, but can potentially metabolize if presented with liquid water for a sufficient duration. Over geological time, rare rain events and physicochemical factors potentially played a major role in selecting micro-organisms that are most adapted to extreme desiccating conditions.

  16. Study of the microwave emissivity characteristics over Gobi Desert

    International Nuclear Information System (INIS)

    Yubao, Qiu; Lijuan, Shi; Wenbo, Wu

    2014-01-01

    The microwave emissivity represents the capacity of the thermal radiation of the surface, and it is the significant parameter for understanding the geophysical processes such as surface energy budget and surface radiation. Different land covers have different emissivity properties, and the Gobi Desert in Central Asia seriously impact the sandstorms occur and develop in China, because of its special geographical environment and surface soil characteristics. In this study half-month averaged microwave emissivity from March 2003 to February 2004 over the Gobi Desert has been estimated. Emissivities in this area at different frequencies, polarization and their seasonal variations are discussed respectively. The results showed that emissivity polarization difference decrease as the frequency increases, and the polarization difference is large (0.03–0.127). The H polarization emissivity increases with increasing frequency, but the V-polarized microwave emissivity is reduced with increasing frequency because of the body scattering. In winter, emissivity decreases sharply in snow covered area, especially for higher frequencies (such as 89GHz). In addition, we compared emissivity with MODIS NDVI data at the same time in the Gobi Desert, and the results indicate that NDVI derived the good negative correlation with microwave emissivity polarization difference at 37GHz

  17. Fog deposition to a Tillandsia carpet in the Atacama Desert

    Science.gov (United States)

    Westbeld, A.; Klemm, O.; Grießbaum, F.; Sträter, E.; Larrain, H.; Osses, P.; Cereceda, P.

    2009-09-01

    In the Atacama Desert, one of the driest places on earth, fog deposition plays an important role for the water balance and for the survival of vulnerable ecosystems. The eddy covariance method, previously applied for the quantification of fog deposition to forests in various parts of the world, was used for the first time to measure deposition of fog water to a desert. In this exploratory study we estimate the amount of water available for the ecosystem by deposition and determine the relevant processes driving fog deposition. This is especially important for the species Tillandsia landbecki living in coastal Atacama at the limit of plant existence with fog and dew being the only sources of water. Between 31 July and 19 August 2008 approximately 2.5 L m-2 of water were made available through deposition. Whole-year deposition was estimated as 25 L m-2. Turbulent upward fluxes occurred several times during the evenings and are explained by the formation of radiation fog. In connection with that, underestimates of the deposition are assumed. More detailed studies covering various seasons and all parameters and fluxes contributing to the local energy balance are suggested. This will help to further develop understanding about the processes of (i) deposition of water to the desert, and (ii) intensification of advection fog through additional formation of radiation fog.

  18. Fog deposition to a Tillandsia carpet in the Atacama Desert

    Energy Technology Data Exchange (ETDEWEB)

    Westbeld, A.; Klemm, O.; Griessbaum, F.; Straeter, E. [Muenster Univ. (Germany). Inst. of Landscape Ecology; Larrain, H. [Pontificia Univ. Catolica de Chile (Chile). Atacama Desert Center ADC; Univ. Bolivariana, Iquique (Chile); Osses, P.; Cereceda, P. [Pontificia Univ. Catolica de Chile, Santiago de Chile (Chile). Inst. of Geography

    2009-07-01

    In the Atacama Desert, one of the driest places on earth, fog deposition plays an important role for the water balance and for the survival of vulnerable ecosystems. The eddy covariance method, previously applied for the quantification of fog deposition to forests in various parts of the world, was used for the first time to measure deposition of fog water to a desert. In this exploratory study we estimate the amount of water available for the ecosystem by deposition and determine the relevant processes driving fog deposition. This is especially important for the species Tillandsia landbecki living in coastal Atacama at the limit of plant existence with fog and dew being the only sources of water. Between 31 July and 19 August 2008 approximately 2.5 L m{sup -2} of water were made available through deposition. Whole-year deposition was estimated as 25 L m{sup -2}. Turbulent upward fluxes occurred several times during the evenings and are explained by the formation of radiation fog. In connection with that, underestimates of the deposition are assumed. More detailed studies covering various seasons and all parameters and fluxes contributing to the local energy balance are suggested. This will help to further develop understanding about the processes of (i) deposition of water to the desert, and (ii) intensification of advection fog through additional formation of radiation fog. (orig.)

  19. Fog deposition to a Tillandsia carpet in the Atacama Desert

    Directory of Open Access Journals (Sweden)

    P. Osses

    2009-09-01

    Full Text Available In the Atacama Desert, one of the driest places on earth, fog deposition plays an important role for the water balance and for the survival of vulnerable ecosystems. The eddy covariance method, previously applied for the quantification of fog deposition to forests in various parts of the world, was used for the first time to measure deposition of fog water to a desert. In this exploratory study we estimate the amount of water available for the ecosystem by deposition and determine the relevant processes driving fog deposition. This is especially important for the species Tillandsia landbecki living in coastal Atacama at the limit of plant existence with fog and dew being the only sources of water. Between 31 July and 19 August 2008 approximately 2.5 L m−2 of water were made available through deposition. Whole-year deposition was estimated as 25 L m−2. Turbulent upward fluxes occurred several times during the evenings and are explained by the formation of radiation fog. In connection with that, underestimates of the deposition are assumed. More detailed studies covering various seasons and all parameters and fluxes contributing to the local energy balance are suggested. This will help to further develop understanding about the processes of (i deposition of water to the desert, and (ii intensification of advection fog through additional formation of radiation fog.

  20. Transitory microbial habitat in the hyperarid Atacama Desert

    Science.gov (United States)

    Schulze-Makuch, Dirk; Wagner, Dirk; Kounaves, Samuel P.; Mangelsdorf, Kai; Devine, Kevin G.; de Vera, Jean-Pierre; Schmitt-Kopplin, Philippe; Grossart, Hans-Peter; Parro, Victor; Kaupenjohann, Martin; Galy, Albert; Schneider, Beate; Airo, Alessandro; Frösler, Jan; Davila, Alfonso F.; Arens, Felix L.; Cáceres, Luis; Solís Cornejo, Francisco; Carrizo, Daniel; Dartnell, Lewis; DiRuggiero, Jocelyne; Flury, Markus; Ganzert, Lars; Gessner, Mark O.; Grathwohl, Peter; Guan, Lisa; Heinz, Jacob; Hess, Matthias; Keppler, Frank; Maus, Deborah; McKay, Christopher P.; Meckenstock, Rainer U.; Montgomery, Wren; Oberlin, Elizabeth A.; Probst, Alexander J.; Sáenz, Johan S.; Sattler, Tobias; Schirmack, Janosch; Sephton, Mark A.; Schloter, Michael; Uhl, Jenny; Valenzuela, Bernardita; Vestergaard, Gisle; Wörmer, Lars; Zamorano, Pedro

    2018-03-01

    Traces of life are nearly ubiquitous on Earth. However, a central unresolved question is whether these traces always indicate an active microbial community or whether, in extreme environments, such as hyperarid deserts, they instead reflect just dormant or dead cells. Although microbial biomass and diversity decrease with increasing aridity in the Atacama Desert, we provide multiple lines of evidence for the presence of an at times metabolically active, microbial community in one of the driest places on Earth. We base this observation on four major lines of evidence: (i) a physico-chemical characterization of the soil habitability after an exceptional rain event, (ii) identified biomolecules indicative of potentially active cells [e.g., presence of ATP, phospholipid fatty acids (PLFAs), metabolites, and enzymatic activity], (iii) measurements of in situ replication rates of genomes of uncultivated bacteria reconstructed from selected samples, and (iv) microbial community patterns specific to soil parameters and depths. We infer that the microbial populations have undergone selection and adaptation in response to their specific soil microenvironment and in particular to the degree of aridity. Collectively, our results highlight that even the hyperarid Atacama Desert can provide a habitable environment for microorganisms that allows them to become metabolically active following an episodic increase in moisture and that once it decreases, so does the activity of the microbiota. These results have implications for the prospect of life on other planets such as Mars, which has transitioned from an earlier wetter environment to today’s extreme hyperaridity.

  1. Palynology in a polar desert, eastern North Greenland

    DEFF Research Database (Denmark)

    Funder, Svend Visby; Abrahamsen, Niels

    1988-01-01

    history back to c. 7,000 years calBP (6,000 years convBP) in this·extreme environment, which presents the coldest thermal regime where vascular plants can grow. The diagram shows that polar desert developed from sparse high arctic tundra at c. 4,300 years calBP (3,900 years convBP), owing...... to reduced summer heat. Also adjacent parts of high arctic Greenland, Canada and Svalbard suffered environmental decline, and polar deserts- presently restricted to a narrow fringe of land at the shores of the Arctic Ocean-were even more restricted before this time. Like other arctic vegetation types, polar...... desert is highly sensitive to summer temperatures, and its southern limit coincides with the isotherm for mean July temperatures of 3.5'C, A comparison with the Northwest European ice-age pollen record shows no evidence of summers as cold as those now prevailing in the extreme north, and the results...

  2. Microbial communities in a High Arctic polar desert landscape

    Directory of Open Access Journals (Sweden)

    Clare M McCann

    2016-03-01

    Full Text Available The High Arctic is dominated by polar desert habitats whose microbial communities are poorly understood. In this study, we used next generation sequencing to describe the α- and β-diversity of polar desert soils from the Kongsfjorden region of Svalbard. Ten phyla consistently dominated the soils and accounted for 95 % of all sequences, with Proteobacteria, Actinobacteria and Chloroflexi being the dominant lineages. In contrast to previous investigations of Arctic soils, Acidobacterial relative abundances were low as were the Archaea throughout the Kongsfjorden polar desert landscape. Lower Acidobacterial abundances were attributed to the circumneutral soil pH in this region which has resulted from the weathering of the underlying carbonate geology. In addition, we correlated previously measured geochemical variables to determine potential controls on the communities. Soil phosphorus, pH, nitrogen and calcium significantly correlated with β-diversity indicating a landscape scale lithological control of soil nutrients which in turn influenced community composition. In addition, soil phosphorus and pH significantly correlated with α- diversity, specifically the Shannon diversity and Chao 1 richness indices.

  3. Water/Pasture Assessment of Registan Desert (Kandahar and Helmand Provinces)

    OpenAIRE

    Toderich, Kristina; Tsukatani, Tsuneo

    2005-01-01

    The desolate desert in Afghanistan's Kandahar and Helmand Provinces was previously populated by thousands of pastoralists until a devastating drought decimated animal herds and forced them to live as IDPs (Internally Displaced Persons) on land bordering the desert. Through funding from UNAMA (United Nations Assistance Mission in Afghanistan), this report assesses conditions in the Registan Desert and border regions to devise solutions to the problems facing Registan Kuchi nomads. A work plan ...

  4. Observation of water and heat fluxes in the Badain Jaran desert, China

    NARCIS (Netherlands)

    Zhang, T.; Wen, J.; Su, Z.; Tian, H.; Zeng, Y.

    Badain Jaran Desert lie in the northwest of the Alashan plateau in western Inner Mongolia of China, between39o20'N to 41o30'N and 100oE to 104oE. It is the 4th largest desert in the world and the second largest desert in China, with an area of 49000 square kilometers and an altitude between 900 and

  5. Mapping of Grocery Stores in Slovak Countryside in Context of Food Deserts

    Directory of Open Access Journals (Sweden)

    Kristína Bilková

    2015-01-01

    Full Text Available The paper is focused on mapping grocery stores in the Slovak countryside with an emphasis on identifying potential food deserts in rural areas. Grocery stores are analyzed in the time period 2001–2011. Food deserts in rural areas are identified by two accessibility measures. The results show the development of food retailing in the Slovak countryside and in potentially threatened localities which can be defined as food deserts.

  6. Multiproxy Holocene paleoclimate records from the southern Peruvian Andes - what new can we learn from the stable carbon isotope composition of high altitude organic matter deposits?

    Science.gov (United States)

    Skrzypek, Grzegorz; Engel, Zbyněk

    2015-04-01

    Interpretation of the Central Andean paleoclimate over the last millennia still represents a research challenge demanding deeper studies [1,2]. Several high-resolution paleoclimate proxies for the last 10,000 years have been developed for the northern hemisphere. However, similar proxies are very limited for South America, particularly for high altitudes where, for example, tree-ring chronologies are not available and instrumental records are very limited. Consequently, our knowledge of high altitude climate changes in arid regions of the Peruvian Andes mainly relies on ice-core and lake deposit studies. In our study, we used a new alternative proxy for interpretation of palaeoclimate conditions based on a peat core taken from the Carhuasanta Valley at the foot of Nevado Mismi in the southern Peruvian Andes (15° 30'S, 71° 43'W, 4809m a.s.l.). The stable carbon isotope composition (δ13C) of Distichia peat reflects mainly the relative variation of the mean air temperature during subsequent growing seasons [3], and allows reconstructions of palaeotemperature changes. In contrast, peat organic carbon concentration (C % wt) records mainly wetness in the valley, directly corresponding to the changes in runoff in the upper part of the catchment. The most prominent climate changes recorded in the peat over last 4ka occurred between 3040 and 2750 cal. yrs BP. The initial warming turned to a very rapid cooling to temperatures at least 2° C lower than the mean for the Late Holocene. Initially drier conditions within this event turned to a short wet phase after 2780 cal. yrs BP, when the temperature increased again. This event coincides with significant changes in peat and ice core records in the Central Andes that match the timing of the global climate event around 2.8 cal. ka BP. Climatic conditions in the study area became relatively dry and stable after the event for about 800 years. Highly variable temperatures and humidity prevailed during the last 2000 years, when

  7. Ice Melt, Sea Level Rise and Superstorms: Evidence from Paleoclimate Data, Climate Modeling, and Modern Observations that 2C Global Warming Could Be Dangerous

    Science.gov (United States)

    Hansen, J.; Sato, Makiko; Hearty, Paul; Ruedy, Reto; Kelley, Maxwell; Masson-Delmotte, Valerie; Russell, Gary; Tselioudis, George; Cao, Junji; Rignot, Eric; hide

    2016-01-01

    We use numerical climate simulations, paleoclimate data, and modern observations to study the effect of growing ice melt from Antarctica and Greenland. Meltwater tends to stabilize the ocean column, inducing amplifying feedbacks that increase subsurface ocean warming and ice shelf melting. Cold meltwater and induced dynamical effects cause ocean surface cooling in the Southern Ocean and North Atlantic, thus increasing Earth's energy imbalance and heat flux into most of the global ocean's surface. Southern Ocean surface cooling, while lower latitudes are warming, increases precipitation on the Southern Ocean, increasing ocean stratification, slowing deepwater formation, and increasing ice sheet mass loss. These feedbacks make ice sheets in contact with the ocean vulnerable to accelerating disintegration. We hypothesize that ice mass loss from the most vulnerable ice, sufficient to raise sea level several meters, is better approximated as exponential than by a more linear response. Doubling times of 10, 20 or 40 years yield multi-meter sea level rise in about 50, 100 or 200 years. Recent ice melt doubling times are near the lower end of the 10-40-year range, but the record is too short to confirm the nature of the response. The feedbacks, including subsurface ocean warming, help explain paleoclimate data and point to a dominant Southern Ocean role in controlling atmospheric CO2, which in turn exercised tight control on global temperature and sea level. The millennial (500-2000-year) timescale of deep-ocean ventilation affects the timescale for natural CO2 change and thus the timescale for paleo-global climate, ice sheet, and sea level changes, but this paleo-millennial timescale should not be misinterpreted as the timescale for ice sheet response to a rapid, large, human-made climate forcing. These climate feedbacks aid interpretation of events late in the prior interglacial, when sea level rose to C6-9m with evidence of extreme storms while Earth was less than 1 C

  8. Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous

    Directory of Open Access Journals (Sweden)

    J. Hansen

    2016-03-01

    Full Text Available We use numerical climate simulations, paleoclimate data, and modern observations to study the effect of growing ice melt from Antarctica and Greenland. Meltwater tends to stabilize the ocean column, inducing amplifying feedbacks that increase subsurface ocean warming and ice shelf melting. Cold meltwater and induced dynamical effects cause ocean surface cooling in the Southern Ocean and North Atlantic, thus increasing Earth's energy imbalance and heat flux into most of the global ocean's surface. Southern Ocean surface cooling, while lower latitudes are warming, increases precipitation on the Southern Ocean, increasing ocean stratification, slowing deepwater formation, and increasing ice sheet mass loss. These feedbacks make ice sheets in contact with the ocean vulnerable to accelerating disintegration. We hypothesize that ice mass loss from the most vulnerable ice, sufficient to raise sea level several meters, is better approximated as exponential than by a more linear response. Doubling times of 10, 20 or 40 years yield multi-meter sea level rise in about 50, 100 or 200 years. Recent ice melt doubling times are near the lower end of the 10–40-year range, but the record is too short to confirm the nature of the response. The feedbacks, including subsurface ocean warming, help explain paleoclimate data and point to a dominant Southern Ocean role in controlling atmospheric CO2, which in turn exercised tight control on global temperature and sea level. The millennial (500–2000-year timescale of deep-ocean ventilation affects the timescale for natural CO2 change and thus the timescale for paleo-global climate, ice sheet, and sea level changes, but this paleo-millennial timescale should not be misinterpreted as the timescale for ice sheet response to a rapid, large, human-made climate forcing. These climate feedbacks aid interpretation of events late in the prior interglacial, when sea level rose to +6–9 m with evidence of extreme storms

  9. Natural resource mitigation, adaptation and research needs related to climate change in the Great Basin and Mojave Desert

    Science.gov (United States)

    Hughson, Debra L.; Busch, David E.; Davis, Scott; Finn, Sean P.; Caicco, Steve; Verburg, Paul S.J.

    2011-01-01

    This report synthesizes the knowledge, opinions, and concerns of many Federal and State land managers, scientists, stakeholders, and partners from a workshop, held at the University of Nevada, Las Vegas, on April 20-22, 2010. Land managers, research scientists, and resource specialists identified common concerns regarding the potential effects of climate change on public lands and natural resources in the Great Basin and Mojave Desert and developed recommendations for mitigation, adaptation, and research needs. Water and, conversely, the effects of drought emerged as a common theme in all breakout sessions on terrestrial and aquatic species at risk, managing across boundaries, monitoring, and ecosystem services. Climate change models for the southwestern deserts predict general warming and drying with increasing precipitation variability year to year. Scientists noted that under these changing conditions the past may no longer be a guide to the future in which managers envision increasing conflicts between human water uses and sustaining ecosystems. Increasing environmental stress also is expected as a consequence of shifting ecosystem boundaries and species distributions, expansion of non-native species, and decoupling of biotic mutualisms, leading to increasingly unstable biologic communities. Managers uniformly expressed a desire to work across management and agency boundaries at a landscape scale but conceded that conflicting agency missions and budgetary constraints often impede collaboration. More and better science is needed to cope with the effects of climate change but, perhaps even more important is the application of science to management issues using the methods of adaptive management based on long-term monitoring to assess the merits of management actions. Access to data is essential for science-based land management. Basic inventories, spatial databases, baseline condition assessments, data quality assurance, and data sharing were identified as top

  10. What influences climate and glacier change in southwestern China?

    Science.gov (United States)

    Yasunari, Teppei J.

    2011-12-01

    The subject of climate change in the Tibetan Plateau (TP) and Himalayas has taken on increasing importance because of the availability of water resources from their mountain glaciers (Immerzeel et al 2010). Many of the glaciers over these regions have been retreating, while some are advancing and stable (Yao et al 2004, Scherler et al 2011). Other studies report that some glaciers in the Himalayas show acceleration of their shrinkage (e.g., Fujita and Nuimura 2011). However, the causes of glacier melting are still difficult to grasp because of the complexity of climatic change and its influence on glacier issues. Despite this, it is vital that we pursue further study to enable future predictions of glacier changes. The paper entitled 'Climate and glacier change in southwestern China during the past several decades' by Li et al (2011) provided carefully analyzed, quality controlled, long-term data on atmospheric temperature and precipitation during the period 1961-2008. The data were obtained from 111 Chinese stations. The researchers performed systematic analyses of temperature and precipitation over the whole southwestern Chinese domain. They discussed those changes in terms of other meteorological components such as atmospheric circulation patterns, radiation and altitude difference, and then showed how these factors could contribute to climate and glacier changes in the region. Air temperature and precipitation are strongly associated with glacier mass balance because of heat balance and the addition of mass when it snows. Temperature warming trends over many places in southwestern China were unequivocally dominant in all seasons and at higher altitudes. This indicates that the heat contribution to the glaciers has been increasing. On the other hand, precipitation has a wider variability in time and space. It is more difficult to clearly understand the effect of precipitation on the climate and glacier melting characteristics in the whole of southwestern China

  11. Epifluorescent direct counts of bacteria and viruses from topsoil of various desert dust storm regions

    Science.gov (United States)

    Gonzalez-Martin, Cristina; Teigell-Perez, Nuria; Lyles, Mark; Valladares, Basilio; Griffin, Dale W.

    2013-01-01

    Topsoil from arid regions is the main source of dust clouds that move through the earth's atmosphere, and microbial communities within these soils can survive long-range dispersion. Microbial abundance and chemical composition were analyzed in topsoil from various desert regions. Statistical analyses showed that microbial direct counts were strongly positively correlated with calcium concentrations and negatively correlated with silicon concentrations. While variance between deserts was expected, it was interesting to note differences between sample sites within a given desert region, illustrating the 'patchy' nature of microbial communities in desert environments.

  12. diurnal and seasonal water relations of the desert phreatophyte prosopis-glandulosa (honey mesquite) in the Sonoran Desert of California

    OpenAIRE

    Nilsen, E. T.; Sharifi, M. R.; Rundel, P. W.; Jarrell, W. M.; Virginia, R. A.

    1983-01-01

    Diurnal and Seasonal water relations were monitored in a population of Prosopis glandulosa var. torreyana in the Sonoran Desert of southern California. Prosopis glandulosa at this research site acquired its water from a ground water source 4-6 m deep. Measurements of diurnal and seasonal cycles of aboveground environmental conditions, soil moisture, and soil water potential (to 6 m depth) were taken to ascertain environmental water availability and water stress. Leaf water potential, leaf con...

  13. Medicinal flora of the Cholistan desert: a review

    International Nuclear Information System (INIS)

    Hmeed, M.; Ashraf, M.; Nawaz, T.; Naz, N.; Ahmad, M.S.A.; Al-Quriany, F.; Younis, A.

    2011-01-01

    The Cholistan desert can be divided into two distinct regions on the basis of topography, soil type and texture, and vegetation structure: the northern Lesser Cholistan and southern Greater Cholistan. The desert is characterized by large saline compacted areas with alluvial clay, sandy ridges and dunes, and semi-stabilized to frequently shifting dunes. The climate is subtropical, harsh, hot and arid, and influenced by seasonal monsoons. Vegetation cover on the sand dunes is comprised by a few tussock-forming grasses including Cenchrus ciliaris, Panicum turgidum and Lasiurus scindicus, along with perennial shrubs Calligonum polygonoides, Leptadenia pyrotechnica and Aerva javanica. Interdunal flats are dominated by grasses, mainly Cymbopogon jwarancusa, Sporobolus ioclados, Panicum antidotale, and Ochthochloa compressa, and tall shrubs Calligonum polygonoides and Capparis decidua. Vegetation of saline patches is specific, dominated by halophytes mainly belonging to family Chenopodiaceae (Amaranthaceae). Many plants of the Cholistan desert, including Neurada procumbens, Aerva javanica, Capparis decidua, Cleome brachycarpa, Dipterygium glaucum, Gisekia pharnacioides, Suaeda fruticosa, Achyranthes aspera, Aerva javanica, Alhagi maurorum, Calotropis procera, Capparis decidua, Zaleya pentandra, Mollugo cerviana, Ziziphus mauritiana, Boerhavia procumbens, Cressa cretica and Crotalaria burhia, are frequently used by the local inhabitants to cure chronic and acute diseases. A variety of medicinally important chemical compounds have been extracted and identified from the plants of the Cholistan desert, including terpenes and triterpenoids, sterols and steroids, phenolics, flavonoids, gums and resins, quinones, anthocyanidines, saponins, antioxidants and fatty acids. Habitat degradation, intensive agricultural practices and over exploitation of resources pose a serious threat to the diversity of ethno botanically important plant species. Allopathic medicines are generally

  14. Strategic sustainable development of groundwater in Thar desert of Pakistan

    International Nuclear Information System (INIS)

    Zaigham, N.A.

    2002-01-01

    Thar Desert forms the extreme southeastern part of Pakistan, covering about 50,000 km/sup 2/ area. It is one of the densely populated deserts of the world. Population of Thar is living primarily on limited agricultural products and by raising goats, sheep, cattle, and camels. The region is characterized by parallel chains of the NE-SW trending parabolic stable sanddunes having desertic varieties of vegetation, generally on windward sides, up to the crests. Interdunal areas are favourable for agricultural activities, where crops are mainly dependent on rainwater. Average rainfall is significant but inconsistent, due to recurrent drought-cycles causing inverse impact on food-production and socio-economic development. In spite of extensive groundwater- exploration projects, accomplished by a number of organizations, the water-crisis of the region could not be controlled, most probably due to lack of systematic exploration and development of deep groundwater potential. Management of the available water- resources is also not adequate, even to sustain a short period of drought-cycle. On recurrence of a drought-cycle, a significant section of the population is compelled to migrate towards other parts of the Sindh province, which affects their socio-economic stability. An integrated research study, based on geo-electric scanning, drilling and seismic-data analyses, has been carried out to delineate subsurface hydro-geological conditions beneath the Thar Desert. Regional gradient maps of surface elevation, top of subsurface Oxidized Zone, top of coal-bearing formation(s) and the deeply buried basement have been prepared, covering almost the whole of That Desert. These gradient maps, analyzed in conjunction with the annual rainfall data, reveal the existence of encouraging subsurface hydrogeological conditions, associated with the sedimentary sequences and the basement. From the results of the study, it is observed that perch water aquifers, commonly being utilized

  15. Response of dominant grass and shrub species to water manipulation: an ecophysiological basis for shrub invasion in a Chihuahuan Desert grassland.

    Science.gov (United States)

    Throop, Heather L; Reichmann, Lara G; Sala, Osvaldo E; Archer, Steven R

    2012-06-01

    Increases in woody vegetation and declines in grasses in arid and semi-arid ecosystems have occurred globally since the 1800s, but the mechanisms driving this major land-cover change remain uncertain and controversial. Working in a shrub-encroached grassland in the northern Chihuahuan Desert where grasses and shrubs typically differ in leaf-level nitrogen allocation, photosynthetic pathway, and root distribution, we asked if differences in leaf-level ecophysiology could help explain shrub proliferation. We predicted that the relative performance of grasses and shrubs would vary with soil moisture due to the different morphological and physiological characteristics of the two life-forms. In a 2-year experiment with ambient, reduced, and enhanced precipitation during the monsoon season, respectively, the encroaching C(3) shrub (honey mesquite Prosopis glandulosa) consistently and substantially outperformed the historically dominant C(4) grass (black grama Bouteloua eriopoda) in terms of photosynthetic rates while also maintaining a more favorable leaf water status. These differences persisted across a wide range of soil moisture conditions, across which mesquite photosynthesis was decoupled from leaf water status and moisture in the upper 50 cm of the soil profile. Mesquite's ability to maintain physiologically active leaves for a greater fraction of the growing season than black grama potentially amplifies and extends the importance of physiological differences. These physiological and phenological differences may help account for grass displacement by shrubs in drylands. Furthermore, the greater sensitivity of the grass to low soil moisture suggests that grasslands may be increasingly susceptible to shrub encroachment in the face of the predicted increases in drought intensity and frequency in the desert of the southwestern USA.

  16. Drought-caused delay in nesting of Sonoran Desert birds and its facilitation of parasite- and predator-mediated variation in reproductive success

    Science.gov (United States)

    McCreedy, Chris; van Riper, Charles

    2015-01-01

    As our understanding of climate change has increased, so has our awareness of the impacts of these changes on biotic systems. Climate models are nearly unanimous in their predictions for increased drought frequency in southwestern North America, and delays in nest initiation due to drought may influence nesting success and productivity for many Sonoran Desert bird species. In southeastern California and western Arizona in 2004–2009, we found negative correlations for 13 of 13 species between nest initiation date and rainfall accumulation during the preceding 4-month winter rainy season. Nesting was delayed more than 3 weeks for some species during extreme droughts in 2006 and 2007. During 2004–2009, we found a significant negative effect of nest initiation date on nest survival probability (β̂ = −0.031 ± 0.005 SE, P nesting delay in nesting success and productivity, in 2010 we conducted a manipulative experiment with Black-tailed Gnatcatchers (Polioptila melanura; BTGN) and Verdins (Auriparus flaviceps; VERD). Following a wet winter, we delayed clutch initiation dates for treatment pairs to match first-egg dates that we observed during droughts in 2006 and 2007. Nest initiation date had a significant negative effect on nest survival of both species (BTGN: β̂ = −1.18 ± 0.27 SE, P nest predation and Brown-headed Cowbird (Molothrus ater) parasitism were the most common causes of nest failure, we conclude that the impacts of climate change–caused drought on annual reproductive output in the Sonoran Desert will be further compounded by parasitism and predation for Black-tailed Gnatcatchers and by predation for Verdins.

  17. A 30-year chronosequence of burned areas in Arizona: effects of wildfires on vegetation in Sonoran Desert Tortoise (Gopherus morafkai) habitats

    Science.gov (United States)

    Shryock, Daniel F.; Esque, Todd C.; Chen, Felicia C.

    2015-01-01

    Fire is widely regarded as a key evolutionary force in fire-prone ecosystems, with effects spanning multiple levels of organization, from species and functional group composition through landscape-scale vegetation structure, biomass, and diversity (Pausas and others, 2004; Bond and Keeley 2005; Pausas and Verdu, 2008). Ecosystems subjected to novel fire regimes may experience profound changes that are difficult to predict, including persistent losses of vegetation cover and diversity (McLaughlin and Bowers, 1982; Brown and Minnich, 1986; Brooks, 2012), losses to seed banks (Esque and others, 2010a), changes in demographic processes (Esque and others, 2004; DeFalco and others, 2010), increased erosion (Soulard and others, 2013), changes in nutrient availability (Esque and others, 2010b), increased dominance of invasive species (Esque and others, 2002; Brooks and others, 2004), and transitions to alternative community states (Davies and others, 2012). In the deserts of the Southwestern United States, fire size and frequency have increased substantially over the last several decades because of an invasive grass/fire feedback cycle (Schmid and Rogers, 1988; D’Antonio and Vitousek, 1992; Swantek and others, 1999; Brooks and Matchett, 2006; Esque and others, 2010a), in which invasive annual species are able to establish fuel loads capable of sustaining large-scale wildfires following years of high rainfall (Esque and Schwalbe, 2002). Native perennial vegetation is not well-adapted to fire in these environments, and widespread, physiognomically dominant species such as creosote bush (Larrea tridentata), Joshua tree (Yucca brevifolia), giant saguaro cactus (Carnegiea gigantea), and paloverde (Parkinsonia spp.) may be reduced or eliminated (Brown and Minnich, 1986; Esque and others, 2006; DeFalco and others, 2010), potentially affecting wildlife populations including the Sonoran and federally threatened Mojave Desert Tortoises (Gopherus morafkai and Gopherus agassizii

  18. Two new species of Indonemoura (Plecoptera: Nemouridae) from Yunnan Province of southwestern China.

    Science.gov (United States)

    Li, Weihai; Wu, Limin; Yang, Ding

    2017-02-09

    Two new species of the nemourid genus Indonemoura are described, Indonemoura curvispina sp. nov. and I. spirocornua sp. nov., from the Gaoligong Mountains of Yunnan Province of southwestern China. The taxonomic relationships with related species are discussed.

  19. Morphological and interlayer geochemical studies on manganese nodules from the southwestern Carlsberg ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.B.; Rajamanickam, G.V.; Karisiddaiah, S.M.; Siddiquie, H.N.

    Mixed facies of manganese nodules from the southwestern Carlberg Ridge have been analysed for Mn, Fe, Ni, Cu, Co and Zn. Seventy one analyses including the averages presented for outer layer, inner layer and near-core material. Morphological studies...

  20. Seasonal mixed layer heat balance of the southwestern tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Foltz, G.R.; Vialard, J.; PraveenKumar, B.; McPhaden, M.J.

    from a long-term moored buoy are used in conjunction with satellite, in situ, and atmospheric reanalysis datasets to analyze the seasonal mixed layer heat balance in the thermocline ridge region of the southwestern tropical Indian Ocean. This region...

  1. Aeolian deposition of Arabia and Somalia sediments on the southwestern continental margin of India

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.

    Kaolinite, smectite, illite and chlorite as major clay minerals and palygorskite and gibbsite in minor quantities have been recorded from the slope of southwestern continental margin of India. Contribution of kaolinite, smectite and gibbsite is from...

  2. Potential for deserts to supply reliable renewable electric power

    Science.gov (United States)

    Labordena, Mercè; Lilliestam, Johan

    2015-04-01

    To avoid dangerous climate change, the electricity systems must be decarbonized by mid-century. The world has sufficient renewable electricity resources for complete power sector decarbonization, but an expansion of renewables poses several challenges for the electricity systems. First, wind and solar PV power are intermittent and supply-controlled, making it difficult to securely integrate this fluctuating generation into the power systems. Consequently, power sources that are both renewable and dispatchable, such as biomass, hydro and concentrating solar power (CSP), are particularly important. Second, renewable power has a low power density and needs vast areas of land, which is problematic both due to cost reasons and due to land-use conflicts, in particular with agriculture. Renewable and dispatchable technologies that can be built in sparsely inhabited regions or on land with low competition with agriculture would therefore be especially valuable; this land-use competition greatly limits the potential for hydro and biomass electricity. Deserts, however, are precisely such low-competition land, and are at the same time the most suited places for CSP generation, but this option would necessitate long transmission lines from remote places in the deserts to the demand centers such as big cities. We therefore study the potential for fleets of CSP plants in the large deserts of the world to produce reliable and reasonable-cost renewable electricity for regions with high and/or rapidly increasing electricity demand and with a desert within or close to its borders. The regions in focus here are the European Union, North Africa and the Middle East, China and Australia. We conduct the analysis in three steps. First, we identify the best solar generation areas in the selected deserts using geographic information systems (GIS), and applying restrictions to minimize impact on biodiversity, soils, human heath, and land-use and land-cover change. Second, we identify

  3. Localization of water channels in the skin of two species of desert toads, Anaxyrus (Bufo) punctatus and Incilius (Bufo) alvarius.

    Science.gov (United States)

    Shibata, Yuki; Takeuchi, Hiro-Aki; Hasegawa, Takahiro; Suzuki, Masakazu; Tanaka, Shigeyasu; Hillyard, Stanley D; Nagai, Takatoshi

    2011-09-01

    Anuran amphibians obtain water by osmosis across their ventral skin. A specialized region in the pelvic skin of semiterrestrial species, termed the seat patch, contains aquaporins (AQPs) that become inserted into the apical plasma membrane of the epidermis following stimulation by arginine vasotocin (AVT) to facilitate rehydration. Two AVT-stimulated AQPs, AQP-h2 and AQP-h3, have been identified in the epidermis of seat patch skin of the Japanese tree frog, Hyla japonica, and show a high degree of homology with those of bufonid species. We used antibodies raised against AQP-h2 and AQP-h3 to characterize the expression of homologous AQPs in the skin of two species of toads that inhabit arid desert regions of southwestern North America. Western blot analysis of proteins gave positive results for AQP-h2-like proteins in the pelvic skin and also the urinary bladder of Anaxyrus (Bufo) punctatus while AQP-h3-like proteins were found in extracts from the pelvic skin and the more anterior ventral skin, but not the urinary bladder. Immunohistochemical observations showed both AQP-h2- and AQP-h3-like proteins were present in the apical membrane of skin from the pelvic skin of hydrated and dehydrated A. punctatus. Further stimulation by AVT or isoproterenol treatment of living toads was not evident. In contrast, skin from hydrated Incilius (Bufo) alvarius showed very weak labeling of AQP-h2- and AQP-h3-like proteins and labeling turned intense following stimulation by AVT. These results are similar to those of tree frogs and toads that occupy mesic habitats and suggest this pattern of AQP expression is the result of phylogenetic factors shared by hylid and bufonid anurans.

  4. Microbial Community and Biochemical Dynamics of Biological Soil Crusts across a Gradient of Surface Coverage in the Central Mojave Desert.

    Science.gov (United States)

    Mogul, Rakesh; Vaishampayan, Parag; Bashir, Mina; McKay, Chris P; Schubert, Keith; Bornaccorsi, Rosalba; Gomez, Ernesto; Tharayil, Sneha; Payton, Geoffrey; Capra, Juliana; Andaya, Jessica; Bacon, Leonard; Bargoma, Emily; Black, David; Boos, Katie; Brant, Michaela; Chabot, Michael; Chau, Danny; Cisneros, Jessica; Chu, Geoff; Curnutt, Jane; DiMizio, Jessica; Engelbrecht, Christian; Gott, Caroline; Harnoto, Raechel; Hovanesian, Ruben; Johnson, Shane; Lavergne, Britne; Martinez, Gabriel; Mans, Paul; Morales, Ernesto; Oei, Alex; Peplow, Gary; Piaget, Ryan; Ponce, Nicole; Renteria, Eduardo; Rodriguez, Veronica; Rodriguez, Joseph; Santander, Monica; Sarmiento, Khamille; Scheppelmann, Allison; Schroter, Gavin; Sexton, Devan; Stephenson, Jenin; Symer, Kristin; Russo-Tait, Tatiane; Weigel, Bill; Wilhelm, Mary B

    2017-01-01

    In this study, we expand upon the biogeography of biological soil crusts (BSCs) and provide molecular insights into the microbial community and biochemical dynamics along the vertical BSC column structure, and across a transect of increasing BSC surface coverage in the central Mojave Desert, CA, United States. Next generation sequencing reveals a bacterial community profile that is distinct among BSCs in the southwestern United States. Distribution of major phyla in the BSC topsoils included Cyanobacteria (33 ± 8%), Proteobacteria (26 ± 6%), and Chloroflexi (12 ± 4%), with Phormidium being the numerically dominant genus. Furthermore, BSC subsurfaces contained Proteobacteria (23 ± 5%), Actinobacteria (20 ± 5%), and Chloroflexi (18 ± 3%), with an unidentified genus from Chloroflexi (AKIW781, order) being numerically dominant. Across the transect, changes in distribution at the phylum ( p < 0.0439) and genus ( p < 0.006) levels, including multiple biochemical and geochemical trends ( p < 0.05), positively correlated with increasing BSC surface coverage. This included increases in (a) Chloroflexi abundance, (b) abundance and diversity of Cyanobacteria, (b) OTU-level diversity in the topsoil, (c) OTU-level differentiation between the topsoil and subsurface, (d) intracellular ATP abundances and catalase activities, and (e) enrichments in clay, silt, and varying elements, including S, Mn, Co, As, and Pb, in the BSC topsoils. In sum, these studies suggest that BSCs from regions of differing surface coverage represent early successional stages, which exhibit increasing bacterial diversity, metabolic activities, and capacity to restructure the soil. Further, these trends suggest that BSC successional maturation and colonization across the transect are inhibited by metals/metalloids such as B, Ca, Ti, Mn, Co, Ni, Mo, and Pb.

  5. Microbial Community and Biochemical Dynamics of Biological Soil Crusts across a Gradient of Surface Coverage in the Central Mojave Desert

    Directory of Open Access Journals (Sweden)

    Rakesh Mogul

    2017-10-01

    Full Text Available In this study, we expand upon the biogeography of biological soil crusts (BSCs and provide molecular insights into the microbial community and biochemical dynamics along the vertical BSC column structure, and across a transect of increasing BSC surface coverage in the central Mojave Desert, CA, United States. Next generation sequencing reveals a bacterial community profile that is distinct among BSCs in the southwestern United States. Distribution of major phyla in the BSC topsoils included Cyanobacteria (33 ± 8%, Proteobacteria (26 ± 6%, and Chloroflexi (12 ± 4%, with Phormidium being the numerically dominant genus. Furthermore, BSC subsurfaces contained Proteobacteria (23 ± 5%, Actinobacteria (20 ± 5%, and Chloroflexi (18 ± 3%, with an unidentified genus from Chloroflexi (AKIW781, order being numerically dominant. Across the transect, changes in distribution at the phylum (p < 0.0439 and genus (p < 0.006 levels, including multiple biochemical and geochemical trends (p < 0.05, positively correlated with increasing BSC surface coverage. This included increases in (a Chloroflexi abundance, (b abundance and diversity of Cyanobacteria, (b OTU-level diversity in the topsoil, (c OTU-level differentiation between the topsoil and subsurface, (d intracellular ATP abundances and catalase activities, and (e enrichments in clay, silt, and varying elements, including S, Mn, Co, As, and Pb, in the BSC topsoils. In sum, these studies suggest that BSCs from regions of differing surface coverage represent early successional stages, which exhibit increasing bacterial diversity, metabolic activities, and capacity to restructure the soil. Further, these trends suggest that BSC successional maturation and colonization across the transect are inhibited by metals/metalloids such as B, Ca, Ti, Mn, Co, Ni, Mo, and Pb.

  6. Paleo-Climate and Glaciological Reconstruction in Central Asia through the Collection and Analysis of Ice Cores and Instrumental Data from the Tien Shan

    International Nuclear Information System (INIS)

    Vladimir Aizen; Donald Bren; Karl Kreutz; Cameron Wake

    2001-01-01

    While the majority of ice core investigations have been undertaken in the polar regions, a few ice cores recovered from carefully selected high altitude/mid-to-low latitude glaciers have also provided valuable records of climate variability in these regions. A regional array of high resolution, multi-parameter ice core records developed from temperate and tropical regions of the globe can be used to document regional climate and environmental change in the latitudes which are home to the vase majority of the Earth's human population. In addition, these records can be directly compared with ice core records available from the polar regions and can therefore expand our understanding of inter-hemispheric dynamics of past climate changes. The main objectives of our paleoclimate research in the Tien Shan mountains of middle Asia combine the development of detailed paleoenvironmental records via the physical and chemical analysis of ice cores with the analysis of modern meteorological and hydrological data. The first step in this research was the collection of ice cores from the accumulation zone of the Inylchek Glacier and the collection of meteorological data from a variety of stations throughout the Tien Shan. The research effort described in this report was part of a collaborative effort with the United State Geological Survey's (USGS) Global Environmental Research Program which began studying radionuclide deposition in mid-latitude glaciers in 1995

  7. A promising location in Patagonia for paleoclimate and paleoenvironmental reconstructions revealed by shallow firn core from Monte San Valentin (Northern patagonia Icefield, Chile)

    DEFF Research Database (Denmark)

    Vimeux, F.; de Angelis, M.; Ginot, P.

    2008-01-01

    temperature is -11.9°C at 10-m depth allowing to expect well preserved both chemical and isotopic signals, unperturbed by water percolation. The dating of the core, on the basis of a multi-proxy approach combining annual layer counting and radionuclide measurements, shows that past environment and climate can......The study of past climate variability from ice core investigations has been largely developed both in polar areas over the past decades and, more recently, in tropical regions, specifically along the South American Andes between 0° and 20°S. However a large gap still remains at mid......-latitudes in the Southern Hemisphere. In this framework, a 15.3-m long shallow firn core has been extracted in March 2005 from the summit plateau of Monte San Valentín (3747 m, 46°35'S, 73°19'W) in the Northern Patagonia Icefield to test its potential for paleoclimate and paleoenvironmental reconstructions. The firn...

  8. Multi-proxy Paleoclimate and CO2 Reconstruction from the Latest Middle Eocene Sedimentary Fill of a Subarctic Kimberlitic Maar Crater

    Science.gov (United States)

    Reyes, A. V.; Wolfe, A. P.; Royer, D. L.; Greenwood, D. R.; Tierney, J. E.; Doria, G.; Gagen, M. H.; Siver, P.; Westgate, J.

    2016-12-01

    Eocene paleoclimate reconstructions are rarely accompanied by parallel estimates of CO2, complicating assessment of the equilibrium climate responses to CO2. We reconstruct temperature, precipitation, and CO2 from latest middle Eocene ( 38 Myrs ago) peats in subarctic Canada, preserved in sediments that record infilling of a kimberlite pipe maar crater. Mutual climatic range analyses of pollen, together with oxygen isotope analyses of a-cellulose from unpermineralized wood and inferenecs from branched glycerol diakyl glycerol tetraethers (GDGTs), reveal a high-latitude humid-temperate forest ecosystem with mean annual temperatures (MATs) >17 °C warmer than present, mean coldest month temperatures above 0 °C, and mean annual precipitation 4x present. Metasequoia stomatal indices and gas-exchange modeling produce median CO2 concentrations of 634 and 432 ppm, respectively, with a consensus median estimate of 494 ppm. Reconstructed MATs are >6 °C warmer than those produced by Eocene climate models forced at 560 ppm CO2, underscoring the capacity for exceptional polar amplification of warming and hydrological intensification under relatively modest CO2 concentrations, once both fast and slow feedbacks become expressed.

  9. Carbon isotopes: variations of their natural abundance. Application to correction of radiocarbon dates, to the study of plant metabolism and to paleoclimate

    International Nuclear Information System (INIS)

    Lerman, J.C.

    1974-01-01

    The radiocarbon activity of contemporaneous samples shows: i) variations in the specific activity of the atmospheric C14, which varies with time and locality. ii) variations due to isotope discrimination, or fractionation, of the carbon isotope ratio during the fixation of carbon by organic or inorganic matter. The variation in the atmospheric concentration of carbon 14 as observed in tree rings are synchronous and of the same amplitude for both hemispheres (southern and northern). A curve for correction of radiocarbon dates of the southern hemisphere is given for the last 500 years. The activity of atmospheric radiocarbon as measured in tree rings varies with latitude, showing a difference of (4.5+-1) per mille between the northern and southern hemispheres, the latter having lower concentration of radiocarbon, equivalent to an age difference of about 35 years. This variation can be explained by a larger exchange of carbon 14 between the atmosphere and the sea in the southern hemisphere to a larger free ocean surface (40%) and a higher agitation by winds. The main differences of the isotope fractionation by different types of plants are correlated to their photosynthetic pathways and thus to the enzyme which effects the primary fixation of carbon. The delta C13 values can be used as basis of a paleoclimate indicator [fr

  10. Paleo-Climate and Glaciological Reconstruction in Central Asia through the Collection and Analysis of Ice Cores and Instrumental Data from the Tien Shan

    Energy Technology Data Exchange (ETDEWEB)

    Vladimir Aizen; Donald Bren; Karl Kreutz; Cameron Wake

    2001-05-30

    While the majority of ice core investigations have been undertaken in the polar regions, a few ice cores recovered from carefully selected high altitude/mid-to-low latitude glaciers have also provided valuable records of climate variability in these regions. A regional array of high resolution, multi-parameter ice core records developed from temperate and tropical regions of the globe can be used to document regional climate and environmental change in the latitudes which are home to the vase majority of the Earth's human population. In addition, these records can be directly compared with ice core records available from the polar regions and can therefore expand our understanding of inter-hemispheric dynamics of past climate changes. The main objectives of our paleoclimate research in the Tien Shan mountains of middle Asia combine the development of detailed paleoenvironmental records via the physical and chemical analysis of ice cores with the analysis of modern meteorological and hydrological data. The first step in this research was the collection of ice cores from the accumulation zone of the Inylchek Glacier and the collection of meteorological data from a variety of stations throughout the Tien Shan. The research effort described in this report was part of a collaborative effort with the United State Geological Survey's (USGS) Global Environmental Research Program which began studying radionuclide deposition in mid-latitude glaciers in 1995.

  11. Tritium water as a marker for the measurement of body water turnover rates in desert livestock, rodent and bird species

    International Nuclear Information System (INIS)

    Khan, M.S.; Ghosh, P.K.; Bohra, R.C.

    1990-01-01

    Tritiated water has been used for estimating body water turnover rates (BWTRs) in desert livestock, rodent and birds. BWTRs in relation to adaption of these animal species to desert environment have been discussed. (author). 5 refs., 2 tabs

  12. Sympatric cattle grazing and desert bighorn sheep foraging

    Science.gov (United States)

    Garrison, Kyle R.; Cain, James W.; Rominger, Eric M.; Goldstein, Elise J.

    2015-01-01

    Foraging behavior affects animal fitness and is largely dictated by the resources available to an animal. Understanding factors that affect forage resources is important for conservation and management of wildlife. Cattle sympatry is proposed to limit desert bighorn population performance, but few studies have quantified the effect of cattle foraging on bighorn forage resources or foraging behavior by desert bighorn. We estimated forage biomass for desert bighorn sheep in 2 mountain ranges: the cattle-grazed Caballo Mountains and the ungrazed San Andres Mountains, New Mexico. We recorded foraging bout efficiency of adult females by recording feeding time/step while foraging, and activity budgets of 3 age-sex classes (i.e., adult males, adult females, yearlings). We also estimated forage biomass at sites where bighorn were observed foraging. We expected lower forage biomass in the cattle-grazed Caballo range than in the ungrazed San Andres range and lower biomass at cattle-accessible versus inaccessible areas within the Caballo range. We predicted bighorn would be less efficient foragers in the Caballo range. Groundcover forage biomass was low in both ranges throughout the study (Jun 2012–Nov 2013). Browse biomass, however, was 4.7 times lower in the Caballo range versus the San Andres range. Bighorn in the Caballo range exhibited greater overall daily travel time, presumably to locate areas of higher forage abundance. By selecting areas with greater forage abundance, adult females in the Caballo range exhibited foraging bout efficiency similar to their San Andres counterparts but lower overall daily browsing time. We did not find a significant reduction in forage biomass at cattle-accessible areas in the Caballo range. Only the most rugged areas in the Caballo range had abundant forage, potentially a result of intensive historical livestock use in less rugged areas. Forage conditions in the Caballo range apparently force bighorn to increase foraging effort by

  13. Diversity and Community Composition of Vertebrates in Desert River Habitats

    Science.gov (United States)

    Free, C. L.; Baxter, G. S.; Dickman, C. R.; Lisle, A.; Leung, L. K.-P.

    2015-01-01

    Animal species are seldom distributed evenly at either local or larger spatial scales, and instead tend to aggregate in sites that meet their resource requirements and maximise fitness. This tendency is likely to be especially marked in arid regions where species could be expected to concentrate at resource-rich oases. In this study, we first test the hypothesis that productive riparian sites in arid Australia support higher vertebrate diversity than other desert habitats, and then elucidate the habitats selected by different species. We addressed the first aim by examining the diversity and composition of vertebrate assemblages inhabiting the Field River and adjacent sand dunes in the Simpson Desert, western Queensland, over a period of two and a half years. The second aim was addressed by examining species composition in riparian and sand dune habitats in dry and wet years. Vertebrate species richness was estimated to be highest (54 species) in the riverine habitats and lowest on the surrounding dune habitats (45 species). The riverine habitats had different species pools compared to the dune habitats. Several species, including the agamid Gowidon longirostris and tree frog Litoria rubella, inhabited the riverine habitats exclusively, while others such as the skinks Ctenotus ariadnae and C. dux were captured only in the dune habitats. The results suggest that, on a local scale, diversity is higher along riparian corridors and that riparian woodland is important for tree-dependent species. Further, the distribution of some species, such as Mus musculus, may be governed by environmental variables (e.g. soil moisture) associated with riparian corridors that are not available in the surrounding desert environment. We conclude that inland river systems may be often of high conservation value, and that management should be initiated where possible to alleviate threats to their continued functioning. PMID:26637127

  14. Substrates and irrigation levels for growing desert rose in pots

    Directory of Open Access Journals (Sweden)

    Ronan Carlos Colombo

    Full Text Available ABSTRACT In the past decades, desert rose has become a very popular ornamental plant, especially among collectors, due to its exotic and sculptural forms. However, it has been grown on a commercial scale only recently, and little is known about how to best manage it as a container-grown plant, or even which potting medium (substrate to recommend. Therefore, the aim of this study was to investigate the interactions between potting media and irrigation levels for growing desert rose as a potted ornamental plant. The experiment was conducted in a greenhouse using a 6 x 2 factorial arrangement with six replications, six potting media and two irrigation levels. The mixes were characterized by measuring their physical properties, specifically the density and water retention capacity (WRC, as well as chemical properties, such as the pH and electrical conductivity (EC. After 210 days, plant growth and plant water consumption were evaluated and measured. A lower dry density for the vermiculite mixes was observed in comparison to that for the sand mixes. However, WRC ranged from 428 to 528 mL L-1 among the mixes, values considered close to ideal. In general, plant growth exhibited higher increases in mixes consisting of coconut fiber + sand or vermiculite, regardless of the irrigation level. Mixes of vermiculite + coconut fiber and sand + coconut fiber can be used to grow desert rose in pots, as long as irrigation is used to maintain the moisture content of the potting medium (mix between 60-70% and 80-90% of the WRC.

  15. The corrosive well waters of Egypt's western desert

    Science.gov (United States)

    Clarke, Frank Eldridge

    1979-01-01

    The discovery that ground waters of Egypt's Western Desert are highly corrosive is lost in antiquity. Inhabitants of the oases have been aware of the troublesome property for many decades and early investigators mention it in their reports concerning the area. Introduction of modern well-drilling techniques and replacements of native wood casing with steel during the 20th century increased corrosion problems and, in what is called the New Valley Project, led to an intense search for causes and corrective treatments. This revealed that extreme corrosiveness results from combined effects of relatively acidic waters with significant concentrations of destructive sulfide ion; unfavorable ratios of sulfate and chloride to less aggressive ions; mineral equilibria and electrode potential which hinder formation of protective films; relative high chemical reaction rates because of abnormal temperatures, and high surface velocities related to well design. There is general agreement among investigators that conventional corrosion control methods such as coating metal surfaces, chemical treatment of the water, and electrolytic protection with impressed current and sacrificial electrodes are ineffective or impracticable for wells in the Western Desert's New Valley. Thus, control must be sought through the use of materials more resistant to corrosion than plain carbon steel wherever well screens and casings are necessary. Of the alternatives considered, stainless steel appears to. be the most promising where high strength and long-term services are required and the alloy's relatively high cost is acceptable. Epoxy resin-bonded fiberglass and wood appear to be practicable, relatively inexpensive alternatives for installations which do. not exceed their strength limitations. Other materials such as high strength aluminum and Monel Metal have shown sufficient promise to. merit their consideration in particular locations and uses. The limited experience with pumping in these desert

  16. Desert bighorn sheep lambing habitat: Parturition, nursery, and predation sites

    Science.gov (United States)

    Karsch, Rebekah C.; Cain, James W.; Rominger, Eric M.; Goldstein, Elise J.

    2016-01-01

    Fitness of female ungulates is determined by neonate survival and lifetime reproductive success. Therefore, adult female ungulates should adopt behaviors and habitat selection patterns that enhance survival of neonates during parturition and lactation. Parturition site location may play an important role in neonatal mortality of desert bighorn sheep (Ovis canadensis mexicana) when lambs are especially vulnerable to predation, but parturition sites are rarely documented for this species. Our objectives were to assess environmental characteristics at desert bighorn parturition, lamb nursery, and predation sites and to assess differences in habitat characteristics between parturition sites and nursery group sites, and predation sites and nursery group sites. We used vaginal implant transmitters (VITs) to identify parturition sites and capture neonates. We then compared elevation, slope, terrain ruggedness, and visibility at parturition, nursery, and lamb predation sites with paired random sites and compared characteristics of parturition sites and lamb predation sites to those of nursery sites. When compared to random sites, odds of a site being a parturition site were highest at intermediate slopes and decreased with increasing female visibility. Odds of a site being a predation site increased with decreasing visibility. When compared to nursery group sites, odds of a site being a parturition site had a quadratic relationship with elevation and slope, with odds being highest at intermediate elevations and intermediate slopes. When we compared predation sites to nursery sites, odds of a site being a predation were highest at low elevation areas with high visibility and high elevation areas with low visibility likely because of differences in hunting strategies of coyote (Canis latrans) and puma (Puma concolor). Parturition sites were lower in elevation and slope than nursery sites. Understanding selection of parturition sites by adult females and how habitat

  17. Spectral identification and quantification of salts in the Atacama Desert

    Science.gov (United States)

    Harris, J. K.; Cousins, C. R.; Claire, M. W.

    2016-10-01

    Salt minerals are an important natural resource. The ability to quickly and remotely identify and quantify salt deposits and salt contaminated soils and sands is therefore a priority goal for the various industries and agencies that utilise salts. The advent of global hyperspectral imagery from instruments such as Hyperion on NASA's Earth-Observing 1 satellite has opened up a new source of data that can potentially be used for just this task. This study aims to assess the ability of Visible and Near Infrared (VNIR) spectroscopy to identify and quantify salt minerals through the use of spectral mixture analysis. The surface and near-surface soils of the Atacama Desert in Chile contain a variety of well-studied salts, which together with low cloud coverage, and high aridity, makes this region an ideal testbed for this technique. Two forms of spectral data ranging 0.35 - 2.5 μm were collected: laboratory spectra acquired using an ASD FieldSpec Pro instrument on samples from four locations in the Atacama desert known to have surface concentrations of sulfates, nitrates, chlorides and perchlorates; and images from the EO-1 satellite's Hyperion instrument taken over the same four locations. Mineral identifications and abundances were confirmed using quantitative XRD of the physical samples. Spectral endmembers were extracted from within the laboratory and Hyperion spectral datasets and together with additional spectral library endmembers fed into a linear mixture model. The resulting identification and abundances from both dataset types were verified against the sample XRD values. Issues of spectral scale, SNR and how different mineral spectra interact are considered, and the utility of VNIR spectroscopy and Hyperion in particular for mapping specific salt concentrations in desert environments is established. Overall, SMA was successful at estimating abundances of sulfate minerals, particularly calcium sulfate, from both hyperspectral image and laboratory sample spectra

  18. Total vertical sediment flux and PM10 emissions from disturbed Chihuahuan Desert Surfaces

    Science.gov (United States)

    Desert surfaces are typically stable and represent some of the oldest landforms on Earth. For surfaces without vegetation, the evolution of a desert pavements of gravel protects the surface from erosive forces and vegetation further protects the surface in arid and semi-arid rangelands. The suscep...

  19. The water economy of South American desert rodents: from integrative to molecular physiological ecology.

    Science.gov (United States)

    Bozinovic, Francisco; Gallardo, Pedro

    2006-01-01

    Rodents from arid and semi-arid habitats live under conditions where the spatial and temporal availability of free water is limited, or scarce, thus forcing these rodents to deal with the problem of water conservation. The response of rodents to unproductive desert environments and water deficits has been intensively investigated in many deserts of the world. However, current understanding of the cellular, systemic and organismal physiology of water economy relies heavily on short-term, laboratory-oriented experiments, which usually focus on responses at isolated levels of biological organization. In addition, studies in small South American mammals are scarce. Indeed xeric habitats have existed in South America for a long time and it is intriguing why present day South American desert rodents do not show the wide array of adaptive traits to desert life observed for rodents on other continents. Several authors have pointed out that South American desert rodents lack physiological and energetic specialization for energy and water conservation, hypothesizing that their success is based more on behavioral and ecological strategies. We review phenotypic flexibility and physiological diversity in water flux rate, urine osmolality, and expression of water channels in South American desert-dwelling rodents. As far as we know, this is the first review of integrative studies at cellular, systemic and organismal levels. Our main conclusion is that South American desert rodents possess structural as well as physiological systems for water conservation, which are as remarkable as those found in "classical" rodents inhabiting other desert areas of the world.

  20. 76 FR 28767 - Desert Southwest Customer Service Region-Rate Order No. WAPA-152

    Science.gov (United States)

    2011-05-18

    ... DEPARTMENT OF ENERGY Western Area Power Administration Desert Southwest Customer Service Region..., Desert Southwest Customer Service Region, Western Area Power Administration, P.O. Box 6457, Phoenix, AZ... Customer Service Region, Western Area Power Administration, P.O. Box 6457, Phoenix, AZ 85005-6457, (602...

  1. 75 FR 13805 - Aspen Group Resources Corp., Commercial Concepts, Inc., Desert Health Products, Inc., Equalnet...

    Science.gov (United States)

    2010-03-23

    ... Concepts, Inc., Desert Health Products, Inc., Equalnet Communications Corp., Geneva Steel Holdings Corp... securities of Commercial Concepts, Inc. because it has not filed any periodic reports since the period ended... accurate information concerning the securities of Desert Health Products, Inc. because it has not filed any...

  2. Translocation as a conservation tool for Agassiz's desert tortoises: Survivorship, reproduction, and movements

    Science.gov (United States)

    K. E. Nussear; C. R. Tracy; P. A. Medica; D. S. Wilson; R. W. Marlow; P. S. Corn

    2012-01-01

    We translocated 120 Agassiz's desert tortoises to 5 sites in Nevada and Utah to evaluate the effects of translocation on tortoise survivorship, reproduction, and habitat use. Translocation sites included several elevations, and extended to sites with vegetation assemblages not typically associated with desert tortoises in order to explore the possibility of moving...

  3. Validation of SWEEP for creep, saltation, and suspension in a desert-oasis ecotone

    Science.gov (United States)

    Wind erosion in the desert-oasis ecotone can accelerate desertification and thus impacts oasis ecological security. Little is known about the susceptibility of the desert-oasis ecotone to wind erosion in the Tarim Basin even though the ecotone is a major source of windblown dust in China. The object...

  4. Cytogeography of Larrea tridentata at the Chihuahuan-Sonoran Desert ecotone

    Science.gov (United States)

    Robert G. Laport; Robert L.. Minckley

    2013-01-01

    The long separation of the Chihuahuan and Sonoran Deserts is reflected in the high species richness and endemism of their floras. Although many endemic species from both deserts reach their distributional limits where the Sierra Madre Occidental massif fragments into smaller mountain complexes in northern Mexico and adjoining areas of the United States, indicator...

  5. Resistance to invasion and resilience to fire in desert shrublands of North America

    Science.gov (United States)

    Matthew L. Brooks; Jeanne C. Chambers

    2011-01-01

    Settlement by Anglo-Americans in the desert shrublands of North America resulted in the introduction and subsequent invasion of multiple nonnative grass species. These invasions have altered presettlement fire regimes, resulted in conversion of native perennial shrublands to nonnative annual grasslands, and placed many native desert species at risk. Effective...

  6. 76 FR 45606 - Desert Renewable Energy Conservation Plan, Habitat Conservation Plan and Possible Land Use Plan...

    Science.gov (United States)

    2011-07-29

    ...-N131; 80221-1112-80221-F2] Desert Renewable Energy Conservation Plan, Habitat Conservation Plan and Possible Land Use Plan Amendment, Southern California: Environmental Impact Statement AGENCY: Fish and..., as amended, for the proposed Desert Renewable Energy Conservation Plan (DRECP). The EIS will be a...

  7. Preliminary survey of bee (Hymenoptera: Anthophila) richness in the northwestern Chihuahuan Desert

    Science.gov (United States)

    Robert L. Minckley; John S. Ascher

    2013-01-01

    Museum records indicate that the peak number of bee species occurs around the Mediterranean Sea and in the warm desert areas of North America, whereas flowering plants are most diverse in the tropics. We examine this biogeographic pattern for the bee species known from a limited area of northeastern Chihuahuan Desert, Mexico/United States. This topographically complex...

  8. 76 FR 29182 - Revisions to the California State Implementation Plan, Mojave Desert Air Quality Management District

    Science.gov (United States)

    2011-05-20

    ... ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 52 [EPA-R09-OAR-2011-0030; FRL-9308-4] Revisions to the California State Implementation Plan, Mojave Desert Air Quality Management District AGENCY... the Mojave Desert Air Quality Management District (MDAQMD) portion of the California State...

  9. 77 FR 11990 - Revisions to the California State Implementation Plan, Mojave Desert Air Quality Management...

    Science.gov (United States)

    2012-02-28

    ... the California State Implementation Plan, Mojave Desert Air Quality Management District and Yolo-Solano Air Quality Management District AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: EPA is proposing to approve revisions to the Mojave Desert Air Quality Management...

  10. 77 FR 11992 - Revisions to the California State Implementation Plan, Mojave Desert Air Quality Management District

    Science.gov (United States)

    2012-02-28

    ... the California State Implementation Plan, Mojave Desert Air Quality Management District AGENCY... limited disapproval of revisions to the Mojave Desert Air Quality Management District (MDAQMD) portion of...,'' Northeast States for Coordinated Air Use Management, December 2000. B. Does the rule meet the evaluation...

  11. Brood desertion by female shorebirds : a test of the differential parental capacity hypothesis on Kentish plovers

    NARCIS (Netherlands)

    Amat, JA; Visser, GH; Perez-Hurtado, A; Arroyo, GM

    2000-01-01

    The aim of this study was to examine whether the energetic costs of reproduction explain offspring desertion by female shorebirds, as is suggested by the differential parental capacity hypothesis. A prediction of the hypothesis is that, in species with biparental incubation in which females desert

  12. Biparentally deserted offspring are viable in a species with intense sexual conflict over care.

    Science.gov (United States)

    Pogány, Ákos; Kosztolányi, András; Miklósi, Ádám; Komdeur, Jan; Székely, Tamás

    2015-07-01

    Desertion of clutch (or brood) by both parents often leads to breeding failure, since in vast majority of birds care by at least one parent is required for any young to fledge. Recent works in a highly polygamous passerine bird, the Eurasian penduline tit (Remiz pendulinus), suggest that biparental clutch desertion is due to intense sexual conflict over care. However, an alternative yet untested hypothesis for biparental desertion is low offspring viability so that the parents abandon the offspring that have poor prospect for survival. Here we test the latter hypothesis in a common garden experiment by comparing the viability of deserted and cared for eggs. We show that embryonic development does not differ between deserted and cared for eggs. Therefore, sexual conflict over care remains the best supported hypothesis for biparental clutch desertion in penduline tits. Our work points out that conflict over care is a potential - yet rarely considered - cause of biparental nest desertion, and a strong alternative for the traditional explanations of low offspring viability, human disturbance or deteriorating ambient environment. Apart from a handful of species, the intensity of sexual conflict has not been quantified, and we call for further studies to consider sexual conflict as a cause of nest desertion. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Reconstructing the origin of Helianthus deserticola: Survival and selection on the desert floor

    NARCIS (Netherlands)

    Gross, B.L.; Kane, D.L.; Lexer, C.; Ludwig, F.; Rosenthal, D.R.; Donovan, L.A.; Rieseberg, L.H.

    2004-01-01

    The diploid hybrid species Helianthus deserticola inhabits the desert floor, an extreme environment relative to its parental species Helianthus annuus and Helianthus petiolaris. Adaptation to the desert floor may have occurred via selection acting on transgressive, or extreme, traits in early

  14. Wilderness restoration: Bureau of Land Management and the Student Conservation Association in the California Desert District

    Science.gov (United States)

    J. Dan Abbe

    2007-01-01

    The California Desert Protection Act of 1994 was the largest park and wilderness legislation passed in the Lower 48 States since the Wilderness Act of 1964. It designated three national parks and 69 Bureau of Land Management wilderness areas. The California Desert and Wilderness Restoration Project is working to restore and revitalize these lands through a public/...

  15. Landscape-scale distribution and density of raptor populations wintering in anthropogenic-dominated desert landscapes

    Science.gov (United States)

    Adam E. Duerr; Tricia A. Miller; Kerri L. Cornell Duerr; Michael J. Lanzone; Amy Fesnock; Todd E. Katzner

    2015-01-01

    Anthropogenic development has great potential to affect fragile desert environments. Large-scale development of renewable energy infrastructure is planned for many desert ecosystems. Development plans should account for anthropogenic effects to distributions and abundance of rare or sensitive wildlife; however, baseline data on abundance and distribution of such...

  16. Giant desiccation fissures on the Black Rock and Smoke Creek Deserts, Nevada

    Science.gov (United States)

    Willden, R.; Mabey, D.R.

    1961-01-01

    Open fissures, from 100 to several hundred feet apart, that have produced polygonal patterns on the Black Rock Desert, Nevada, are believed to be giant desiccation cracks resulting from a secular trend toward aridity in the last few decades. Similar features on the Smoke Creek Desert probably have the same origin.

  17. Seeing desert as wilderness and as landscape—an exercise in visual thinking approaches

    Science.gov (United States)

    John Opie

    1979-01-01

    Based on the components and program of VRVA (Visual Resources Values Assessment), a behavioral history of the visitor's perception of the American desert is examined. Emphasis is placed upon contrasts between traditional eastern "garden-park" viewpoints and contemporary desert scenery experiences. Special attention is given to the influence of John...

  18. Influence of shrubs on soil chemical properties in Alxa desert steppe, China

    Science.gov (United States)

    Hua Fu; Shifang Pei; Yaming Chen; Changgui Wan

    2007-01-01

    Alxa desert steppe is one of severely the degraded rangelands in the Northwest China. Shrubs, as the dominant life form in the desert steppe, play an important role in protecting this region from further desertification. Chemical properties of three soil layers (0 to 10, 10 to 20 and 20 to 30 cm) at three locations (the clump center [A], in the periphery of shrub...

  19. Hydrological indications of aeolian salts in mid-latitude deserts of ...

    Indian Academy of Sciences (India)

    Hydrological indications of aeolian salts in mid-latitude deserts of northwestern China. B Q Zhu. Supplementary data. Figure S1. Photograph views of Quaternary and modern sediments of aeolian and lacustrine/fluvial facies that consisted of clay and sand/silt sand alternations in the Taklamakan and Badanjilin Deserts.

  20. 78 FR 143 - Desert Mining, Inc., Eagle Broadband, Inc., Endovasc, Inc., Environmental Oil Processing...

    Science.gov (United States)

    2013-01-02

    ... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] Desert Mining, Inc., Eagle Broadband, Inc., Endovasc, Inc., Environmental Oil Processing Technology Corp., Falcon Ridge Development, Inc., Fellows... that there is a lack of current and accurate information concerning the securities of Desert Mining...

  1. Southwestern Federal Power System 1995 Financial Statement audit under the Chief Financial Officers Act (WR-FC-96-02)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-22

    The Southwestern Federal Power System encompasses the operation of 24 hydroelectric power plants by the U.S. Army Corps of Engineers and the marketing of power and energy from those plants by the Southwestern Power Administration of the U.S. Department of Energy. To integrate the operation of these hydroelectric generating plants and to transmit power from the dams to its customers, Southwestern Power Administration (Southwestern) maintains 2,220 kilometers (1,380 miles) of high-voltage transmission lines, 24 substations, and 46 microwave and VHF radio sites. Southwestern`s headquarters are in Tulsa, Oklahoma; its dispatch center is in Springfield, Missouri; and its maintenance crews are based in Jonesboro, Arkansas, in Gore and Tupelo, Oklahoma, and in Springfield, Missouri. Three offices - Power Marketing and Delivery, Maintenance, and Administration and Rates - are responsible for meeting Southwestern`s mission. Twelve of the 24 generating plants are scheduled directly by Southwestern, and a total of 19 contribute to the interconnected system operations. Generation at the five remaining projects (Denison, Narrows, Sam Rayburn, Whitney, and Willis) is used to serve specific customer loads. At the end of fiscal year 1995, Southwestern marketed power and energy to 10 generation and transmission cooperatives, one distribution cooperative, three military installations, 44 municipal utilities, and three municipal utility joint-action agencies. One of the joint-action agencies has its own allocation of power from Southwestern; the other two serve 33 municipal utilities to whom Southwestern has allocated power. The total number of power allocation customers is 92. Additionally, excess energy is occasionally sold to non-allocation utilities.

  2. Attitude to rehabilitative counselling in southwestern Nigerian prisons.

    Science.gov (United States)

    A Alao, Kayode; F Adebowale, Olusegun

    2014-01-01

    The purpose of this paper was to examine the attitudes of prison inmates and warders (prison staff) to rehabilitative counselling and its relationship to their prison status on one hand and their educational attainment on the other. The study adopts a descriptive survey research design. In all 123 prison inmates and 110 warders were selected by stratified random sampling from Osogbo prison headquarters, as well as Ilesa and Ile-Ife prisons in southwestern Nigeria. Data were collected through a self-constructed questionnaire titled "inmate and prison staff attitude to rehabilitation counselling". Data collected were analysed using percentages and χ2 statistics. The results showed that the prison inmates and staff possessed positive attitude to rehabilitative counselling. No significant difference was found between the attitudes of prison inmates and staff members or on the basis of their prison statuses. However, the study found a significant relationship between the prison inmates' attitude to rehabilitative counselling and their educational attainment. Research LIMITATIONS/IMPLICATIONS: Statutory provision needs be made for professional rehabilitative counselling in Nigerian prisons in contrast to the religious instructions currently being allowed prisoners. Educational opportunities should be provided to ensure that the knowledge so obtained complements the rehabilitative counselling. Originality/value - This paper fulfils an identified need to study the attitude towards rehabilitative counselling.

  3. MIDDLE TRIASSIC AUTOCLASTIC DEPOSITS FROM SOUTHWESTERN BOSNIA AND HERZEGOVINA

    Directory of Open Access Journals (Sweden)

    Duje Smirčić

    2016-06-01

    Full Text Available Middle Triassic volcanic and volcaniclastic rocks have been recognized at several localities near Bosansko Grahovo, in southwestern part of Bosnia and Herzegovina in the External Dinarides. Peculiar types of autoclastic rocks were investigated. These are peperites and hyaloclastites. Regarding specific structures, mineral composition and micropetrographic characteristics it was possible to further differentiate hyaloclastites into in situ hyaloclastites and slightly resedimented hyaloclastites that represent genetic succession. All rock types occurred in a deep sea troughs that formed as a consequence of Middle Triassic extensional tectonic and rift related wrench faulting. In situ hyaloclastites and slightly resedimented hyaloclastites were formed due to quenching at the contact of lava effusions with sea water. Genesis of peperites is related to lava emplacement in unconsolidated water saturated lime mudstones that were deposited in deep sea basin. All investigated rock types represent first findings of autoclastic deposits in the External Dinarides. Biostratigraphic constraints achieved by means of conodont species Neogondolella excentrica, Paragondolella excelsa, Paragondolella trammeri and Gladigondolella tethydis indicate Late Anisian to Early Ladinian interval of the autoclastic deposits from Bosansko Grahovo.

  4. Drought-induced vegetation stress in southwestern North America

    International Nuclear Information System (INIS)

    Zhang Xiaoyang; Goldberg, Mitchell; Tarpley, Dan; Kogan, Felix; Yu Yunyue; Friedl, Mark A; Morisette, Jeffrey

    2010-01-01

    Trends towards earlier greenup and increased average greenness have been widely reported in both humid and dry ecosystems. By analyzing NOAA (National Oceanic and Atmospheric Administration) AVHRR (Advanced Very High Resolution Radiometer) data from 1982 to 2007, we report complex trends in both the growing season amplitude and seasonally integrated vegetation greenness in southwestern North America and further highlight regions consistently experiencing drought stress. In particular, greenness measurements from 1982 to 2007 show an increasing trend in grasslands but a decreasing trend in shrublands. However, vegetation greenness in this period has experienced a strong cycle, increasing from 1982 to 1993 but decreasing from 1993 to 2007. The significant decrease during the last decade has reduced vegetation greenness by 6% in shrublands and 13% in grasslands (16% and 21%, respectively, in the severe drought years). The greenness cycle correlates to both annual precipitation and dry season length derived from NOAA North America Regional Reanalysis data. If drought events continue as predicted by climate models, they will exacerbate ecosystem degradation and reduce carbon uptake.

  5. Is southwestern China experiencing more frequent precipitation extremes?

    International Nuclear Information System (INIS)

    Liu, Meixian; Xu, Xianli; Wang, Kelin; Sun, Alexander Y; Liu, Wen; Zhang, Xiaoyan

    2014-01-01

    Climate extremes have and will continue to cause severe damages to buildings and natural environments around the world. A full knowledge of the probability of the climate extremes is important for the management and mitigation of natural hazards. Based on Mann–Kendall trend test and copulas, this study investigated the characteristics of precipitation extremes as well as their implications in southwestern China (Yunnan, Guangxi and Guizhou Province), through analyzing the changing trends and probabilistic characteristics of six indices, including the consecutive dry days, consecutive wet days, annual total wet day precipitation, heavy precipitation days (R25), max 5 day precipitation amount (Rx5) and the rainy days (RDs). Results showed that the study area had generally become drier (regional mean annual precipitation decreased by 11.4 mm per decade) and experienced enhanced precipitation extremes in the past 60 years. Relatively higher risk of drought in Yuanan and flood in Guangxi was observed, respectively. However, the changing trends of the precipitation extremes were not spatially uniform: increasing risk of extreme wet events for Guangxi and Guizhou, and increasing probability of concurrent extreme wet and dry events for Yunnan. Meanwhile, trend analyses of the 10 year return levels of the selected indices implied that the severity of droughts decreased in Yunnan but increased significantly in Guangxi and Guizhou, and the severity of floods increased in Yunnan and Guangxi in the past decades. Hence, the policy-makers need to be aware of the different characterizations and the spatial heterogeneity of the precipitation extremes. (letters)

  6. Entomologic inoculation rates of Anopheles arabiensis in southwestern Ethiopia.

    Science.gov (United States)

    Massebo, Fekadu; Balkew, Meshesha; Gebre-Michael, Teshome; Lindtjørn, Bernt

    2013-09-01

    We collected anophelines every second week for one year from randomly selected houses in southwestern Ethiopia by using Centers for Disease Control (CDC) light traps, pyrethrum spray catches, and artificial pit shelter constructions to detect circumsporozoite proteins and estimate entomologic inoculation rates (EIRs). Of 3,678 Anopheles arabiensis tested for circumsporozoite proteins, 11 were positive for Plasmodium falciparum and three for P. vivax. The estimated annual P. falciparum EIR of An. arabiensis was 17.1 infectious bites per person per year (95% confidence interval = 7.03-34.6) based on CDC light traps and 0.1 infectious bites per person per year based on pyrethrum spray catches. The P. falciparum EIRs from CDC light traps varied from 0 infectious bites per person per year (in 60% of houses) to 73.2 infectious bites per person per year in the house nearest the breeding sites. Risk of exposure to infectious bites was higher in wet months than dry months, with a peak in April (9.6 infectious bites per person per month), the period of highest mosquito density.

  7. Hydrogeology of the Judith River Formation in southwestern Saskatchewan, Canada

    Science.gov (United States)

    Ferris, David; Lypka, Morgan; Ferguson, Grant

    2017-11-01

    The Judith River Formation forms an important regional aquifer in southwestern Saskatchewan, Canada. This aquifer is used for domestic and agricultural purposes in some areas and supports oil and gas production in other areas. As a result, the available data come from a range of sources and integration is required to provide an overview of aquifer characteristics. Here, data from oil and gas databases are combined with data from groundwater resource assessments. Analysis of cores, drill-stem tests and pumping tests provide a good overview of the physical hydrogeology of the Judith River Aquifer. Water chemistry data from oil and gas databases were less helpful in understanding the chemical hydrogeology due contamination of samples and unreliable laboratory analyses. Analytical modeling of past pumping in the aquifer indicates that decreases in hydraulic head exceeding 2 m are possible over distances of 10s of kilometers. Similar decreases in head should be expected for additional large withdrawals of groundwater from the Judith River Aquifer. Long-term groundwater abstraction should be limited by low pumping rates. Higher pumping rates appear to be possible for short-term uses, such as those required by the oil and gas industry.

  8. The melliferous potential of apiflora of southwestern Vojvodina (Serbia

    Directory of Open Access Journals (Sweden)

    Mačukanović-Jocić Marina P.

    2016-01-01

    Full Text Available The individual and community-level melliferous potential of apiflora was evaluated in southwestern Vojvodina in order to assess its significance and contribution to the bee pasture. Seven plant communities belonging to ruderal, segetal and floodplain type of vegetation, with a total of 279 plant species were registered. Apifloristic and phytocoenological investigations included the determination and analysis of honey plants using the following parameters: total number, percentage, abundance and frequency of these species in the communities, as well as their intensity of pollen and nectar production. The coenotic coefficient of melliferousness (CCm indicating the melliferous potential of each community, was calculated based on the above parameters. Although the greatest number of melliferous species was found in the ass. Chenopodio-Ambrosietum artemisiifoliae (132, the highest percentage (80% of them was registered in the ass. Consolido-Polygonetum avicularis. Considering the coefficients of nectar and pollen production, the most valuable honey plants commonly present in the majority of communities were: Cirsium arvense, Rubus caesius, Lythrum salicaria, Daucus carota, Trifolium pratense, Dipsacus laciniatus, Medicago sativa, Asclepias syriaca, Cichorium intybus and Taraxacum officinale. The low abundance and frequency of melliferous species within the Consolido-Polygonetum avicularis, Polygonetum convolvulo-avicularis and Populetum nigrae-albae communities indicated their poor contribution to the bee pasture. Within ruderal vegetation, the highest CCm was registered in Amorpho-Typhaetum, providing, theoretically, the richest food resource for the honeybees in the investigated area. [Projekat Ministarstva nauke Republike Srbije, br. 46009 i br. 173018

  9. Source rock potential of middle cretaceous rocks in Southwestern Montana

    Science.gov (United States)

    Dyman, T.S.; Palacas, J.G.; Tysdal, R.G.; Perry, W.J.; Pawlewicz, M.J.

    1996-01-01

    The middle Cretaceous in southwestern Montana is composed of a marine and nonmarine succession of predominantly clastic rocks that were deposited along the western margin of the Western Interior Seaway. In places, middle Cretaceous rocks contain appreciable total organic carbon (TOC), such as 5.59% for the Mowry Shale and 8.11% for the Frontier Formation in the Madison Range. Most samples, however, exhibit less than 1.0% TOC. The genetic or hydrocarbon potential (S1+S2) of all the samples analyzed, except one, yield less than 1 mg HC/g rock, strongly indicating poor potential for generating commercial amounts of hydrocarbons. Out of 51 samples analyzed, only one (a Thermopolis Shale sample from the Snowcrest Range) showed a moderate petroleum potential of 3.1 mg HC/g rock. Most of the middle Cretaceous samples are thermally immature to marginally mature, with vitrinite reflectance ranging from about 0.4 to 0.6% Ro. Maturity is high in the Pioneer Mountains, where vitrinite reflectance averages 3.4% Ro, and at Big Sky Montana, where vitrinite reflectance averages 2.5% Ro. At both localities, high Ro values are due to local heat sources, such as the Pioneer batholith in the Pioneer Mountains.

  10. An Ethnographic Meta-Synthesis of Three Southwestern Rural Studies.

    Science.gov (United States)

    Averill, Jennifer B

    2016-01-01

    The objectives were to synthesize cumulative findings across three critical ethnographic, community-partnered studies in the southwestern United States and to describe the process of meta-ethnography for that analysis. The meta-ethnography followed the design of Noblit and Hare for constructing an analysis of composite data, informed by community-based participatory research and Stringer's ethnographic strategies of Look-Think-Act. The three studies occurred in rural settings of Colorado and New Mexico, engaging 129 total participants, along with community organizations and agencies as partners. Methods consisted of detailed review of each original study, mapping of major concepts and themes, and general analysis, interpretation, and synthesis across the studies. Overall themes were: health is the capacity to care for oneself and do work, meaningful relationships are key in health care interactions, patterns of discrimination persist in rural settings, poor literacy and health literacy are barriers, and food insecurity is a growing concern for older rural adults. Resolutions involve practice, policy, and research and must incorporate all stakeholder groups in rural settings; a participatory approach is critical to prioritize and impact existing inequities; and work is needed to extend education and understanding of multiple cultures, groups, customs, and rural contexts. © 2015 Wiley Periodicals, Inc.

  11. Prediction of domestic violence against married women in southwestern Turkey.

    Science.gov (United States)

    Izmirli, Gulsen O; Sonmez, Yonca; Sezik, Mekin

    2014-12-01

    To determine the prevalence of, and independent risk factors for various domestic violence categories among married women of reproductive age in southwestern Turkey. The present cross-sectional study included 260 randomly selected women registered to a family physician in the district of Gönen, Isparta. During home visits between October 1 and December 31, 2012, the women completed a questionnaire that included between four and eight questions for each violence category (physical, verbal, economic, emotional, and sexual) to assess the lifetime presence of domestic violence. Logistic regression models with backward elimination were constructed to define independent risk factors for domestic violence. In total, 176 (67.7%) women reported any type of domestic violence at least once in their lifetime. Verbal/psychological abuse was the most frequent type (reported by 121 [46.5%] women). Living in a village, young age (19-29 years) of the husband, adolescent age (violence. Attention should be given to area of residence, age of both partners at marriage, adolescent marriage, and husband characteristics during screening for domestic violence. Copyright © 2014 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

  12. Some geophysical constraints to dynamic processes in the Southwestern Mediterranean

    Directory of Open Access Journals (Sweden)

    P. Chiozzi

    1996-06-01

    Full Text Available The total tectonic subsidence, thermal state and seismotectonic regime have been analysed to better constrain the dynamic processes which originated the basins of the Southwestern Mediterranean. It is argued that backarc extension and oceanic spreading are the possible and main processes which took place within a compressional framework, driven by the interaction between the African and European plates. As inferred by both subsidence and heat-flux data, in the central part of the Algerian-Balearic basin the crust is oceanic, 20 Ma old on average, originated by a spreading phase, which also affected the Ligurian-Provençal basin. The Alboran basin, which is underlain by stretched continental crust, shows an intermediate seismic activity and a few deep events, explainable by a gravitational collapse of cold lithosphere. After a review of the most recent geodynamical hypotheses, an evolutionary scheme is attempted envisaging the lateral continental escape of the Gibraltar arc. Within a convergent tectonic framework, some lithospheric material could translate almost perpendicular to the convergence direction, and undergo a lateral subduction process, secondary to the main boundary between plates.

  13. Analysis of desert rose using PIXE and RBS techniques

    International Nuclear Information System (INIS)

    Al-Kofahi, M.M.; Hallak, A.B.; Al-Juwair, H.A.; Saafin, A.K.

    1993-01-01

    Particle-induced x-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) were used to analyse desert rose geological samples. Samples from the rose core and from the rose peripherals were studied. All samples were found to contain C, N, O, Na, Mg, Si, S, Cl, K, Ca, Ti, Mn, Fe and Sr. Core samples were found to contain more silicon than peripheral samples. The extra silicon in the rose core may suggest a mechanism for the formation of the rose through crystal growth on a seed of silicon. (author)

  14. Robot Science Autonomy in the Atacama Desert and Beyond

    Science.gov (United States)

    Thompson, David R.; Wettergreen, David S.

    2013-01-01

    Science-guided autonomy augments rovers with reasoning to make observations and take actions related to the objectives of scientific exploration. When rovers can directly interpret instrument measurements then scientific goals can inform and adapt ongoing navigation decisions. These autonomous explorers will make better scientific observations and collect massive, accurate datasets. In current astrobiology studies in the Atacama Desert we are applying algorithms for science autonomy to choose effective observations and measurements. Rovers are able to decide when and where to take follow-up actions that deepen scientific understanding. These techniques apply to planetary rovers, which we can illustrate with algorithms now used by Mars rovers and by discussing future missions.

  15. Impact of Precipitation Fluctuation on Desert-Grassland ANPP

    Directory of Open Access Journals (Sweden)

    Liangxu Liu

    2016-11-01

    Full Text Available Precipitation change has significantly influenced annual net primary productivity (ANPP at either annual or seasonal scales in desert steppes in arid and semi-arid regions. In order to reveal the process of precipitation driving ANPP at different time scales, responses of different ANPP levels to the inter-annual and intra-annual precipitation fluctuations were analyzed. ANPP was reversed by building a ground reflectance spectrum model, from 2000 to 2015, using the normalized differential vegetation index of the Moderate-Resolution Imaging Spectroradiometer (MODIS-NDVI data at 250 m × 250 m spatial resolution. Since the description of the differently expressing forms of precipitation are not sufficient in former studies in order to overcome the deficiency of former studies, in this study, intra-annual precipitation fluctuations were analyzed not only with precipitation of May–August, June–August, July–August, and August, respectively, which have direct influence on vegetation productivity within the year, but quantitative description, vector precipitation (R, concentration ratio (Cd, and concentration period (D, were also used to describe the overall characteristics of intra-annual precipitation fluctuations. The concentration ratio and the maximum precipitation period of the intra-annual precipitation were represented by using monthly precipitation. The results showed that: (1 in the period from 1971 to 2015, the maximum annual precipitation is 3.76 times that of the minimum in the Urat desert steppe; (2 vector precipitation is more significantly related to ANPP (r = 0.7724, p = 0.000 compared to meteorological annual precipitation and real annual precipitation influence; and (3 annual precipitation is almost concentrated in 5–8 months and monthly precipitation accumulation has significantly effected ANPP, especially in the period of June–August, since the vegetation composition in the study area was mainly sub-shrubs and perennial

  16. Geophysical Reservoir Evaluation of Obaiyed Field, Western Desert, Egypt

    OpenAIRE

    Farag, Mohamed Ibrahim Abdel-Fattah Ibrahim

    2010-01-01

    Die Obaiyed-Gaslagerstätte liegt in der westlichen Wüste Ägyptens, etwa 50 km südlich der Mittelmeerküste. Das produzierte Gas entstammt dem oberen Safa-Member der Khatatba Formation (Mitteljura). Das obere Safa Reservoir ist zu einem wichtigen Ziel in der Erforschung des Obaiyed-Feldes geworden und hat dazu beigetragen, die Exploration im nordwestlichen Teil der Western Desert in Ägypten neu zu beleben. Daher ist das Hauptziel dieser Arbeit ist die Bewertung des Kohlenwasserstoff-Potentials ...

  17. Invited Commentary: More Surprises From a Gene Desert

    OpenAIRE

    Wacholder, Sholom; Yeager, Meredith; Liao, Linda M.

    2012-01-01

    Pleiotropy across the 8q24 region is perhaps the most intriguing of the genome-wide association findings relating to cancer. This region of chromosome 8 is a gene desert, far from any recognized genes. Guarrera et al., whose work is reported in this issue (Am J Epidemiol. 2012;175(6):479–487), took an epidemiologic approach to learn more about the 8q24 region. They capitalized on their ascertainment of other endpoints in members of the cohort at the Turin site of the European Prospective Inve...

  18. Desert pioneers go high tech in uranium project

    International Nuclear Information System (INIS)

    1988-01-01

    The Kintyre uranium deposit discovered in 1985 in Western Australia's Great Sandy Desert by CRA Exploration is a highly competitive, easy to mine deposit, estimated at 35,000 tonnes of uranium oxide. Since its discovery CRA has spent $20 million on evaluation drilling and exploration and will spend another $10 million in 1988. Despite its remoteness the latest technology is being used, with sophisticated computer and assaying facilities, including an automatic X-ray fluorescence spectrometer, being established on site. A CRA-built radiometric ore sorter is being tested there which could cut ore processing costs

  19. Variation of Desert Soil Hydraulic Properties with Pedogenic Maturity

    Science.gov (United States)

    Nimmo, J. R.; Perkins, K. S.; Mirus, B. B.; Schmidt, K. M.; Miller, D. M.; Stock, J. D.; Singha, K.

    2006-12-01

    Older alluvial desert soils exhibit greater pedogenic maturity, having more distinct desert pavements, vesicular (Av) horizons, and more pronounced stratification from processes such as illuviation and salt accumulation. These and related effects strongly influence the soil hydraulic properties. Older soils have been observed to have lower saturated hydraulic conductivity, and possibly greater capacity to retain water, but the quantitative effect of specific pedogenic features on the soil water retention or unsaturated hydraulic conductivity (K) curves is poorly known. With field infiltration/redistribution experiments on three different-aged soils developed within alluvial wash deposits in the Mojave National Preserve, we evaluated effective hydraulic properties over a scale of several m horizontally and to 1.5 m depth. We then correlated these properties with pedogenic features. The selected soils are (1) recently deposited sediments, (2) a soil of early Holocene age, and (3) a highly developed soil of late Pleistocene age. In each experiment we ponded water in a 1-m-diameter infiltration ring for 2.3 hr. For several weeks we monitored subsurface water content and matric pressure using surface electrical resistance imaging, dielectric-constant probes, heat-dissipation probes, and tensiometers. Analysis of these data using an inverse modeling technique gives the water retention and K properties needed for predictive modeling. Some properties show a consistent trend with soil age. Progressively more developed surface and near-surface features such as desert pavement and Av horizons are the likely cause of an observed consistent decline of infiltration capacity with soil age. Other properties, such as vertical flow retardation by layer contrasts, appear to have a more complicated soil-age dependence. The wash deposits display distinct depositional layering that has a retarding effect on vertical flow, an effect that may be less pronounced in the older Holocene soil

  20. Should I stay or should I go? Female brood desertion and male counterstrategy in rock sparrows

    DEFF Research Database (Denmark)

    Griggio, Matteo; Matessi, Giuliano; Pilastro, Andrea

    2005-01-01

    petronia), a species in which females can desert their first brood before the nestlings from the first brood leave the nest. We predicted that the male would either desert the brood first or stay even if this implied the risk of caring for the brood alone. We found that males mated to loaded females did...... not leave but stayed and significantly increased their courtship rate and mate guarding. Unexpectedly, they also increased their food provisioning to the nestlings, even though loaded females did not reduce their nestling-feeding rate. The increase in male feeding rate may be explained as a way for the male...... to reduce the female's propensity to switch mate and desert or to increase her propensity to copulate with the male to obtain paternity in her next brood. Altogether, our results demonstrate that the perception of the risk of being deserted by the female does not necessarily induce males to desert first...

  1. Passionate Perspectives: Global Change Emersion in Southwestern Dust and Waters

    Science.gov (United States)

    Byrne, J. M.; Little, L. J.

    2014-12-01

    "Tell me, and I'll forget. Show me, and I may remember. But involve me, and I'll understand" (attributed to various philosophers). How many professors have shared 20-30 days traveling, hiking, camping, and Coleman stove cooking with 25-50 young adults? Sixteen times! Way over a year on a field trip…holy sh*t! Tired… but happy. We have offered an extended camping field trip that feature the highlands and deserts of Utah, Arizona, Mexico and California; with side trips to Colorado and New Mexico. Two science and one social science courses focus on global environmental change, water and human development. The discussion will center on the short and long term evolution(s) that have occurred: who, what, where, when and why, and perhaps most important, HOW! These tours are amazing learning experiences that go way beyond any classroom. Many of our students have found the expedition to be life changing - or life awakening. Hopefully we can squeeze the essence into our few minutes of fame :) "Once more I am roaring drunk with the lust of life and adventure and unbearable beauty... Adventure seems to beset me on all quarters without my even searching for it... Though not all my days are as wild as this, each one holds its surprises, and I have seen almost more beauty than I can bear." - Everett Reuss

  2. Long-Term Observations of Dust Storms in Sandy Desert Environments

    Science.gov (United States)

    Yun, Hye-Won; Kim, Jung-Rack; Choi, Yun-Soo

    2015-04-01

    Mineral dust occupies the largest portion of atmospheric aerosol. Considering the numerous risks that dust poses for socioeconomic and anthropogenic activities, it is crucial to understand sandy desert environments, which frequently generate dust storms and act as a primary source of atmospheric aerosol. To identify mineral aerosol mechanisms, it is essential to monitor desert environmental factors involving dust storm generation in the long term. In this study, we focused on two major environmental factors: local surface roughness and soil moisture. Since installments of ground observation networks in sandy deserts are unfeasible, remote sensing techniques for mining desert environmental factors were employed. The test area was established within the Badain Jaran and Kubuqi Deserts in Inner Mongolia, China, where significant seasonal aeolian processes emit mineral dust that influences all of East Asia. To trace local surface roughness, we employed a multi-angle imaging spectroradiometer (MISR) image sequence to extract multi-angle viewing (MAV) topographic parameters such as normalized difference angular index, which represents characteristics of the target desert topography. The backscattering coefficient from various space-borne SAR and stereotopography were compared with MAV observations to determine calibrated local surface roughness. Soil moisture extraction techniques from InSAR-phase coherence stacks were developed and compiled with advanced scatterometer (ASCAT) soil moisture data. Combined with metrological information such as the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA interim, correlations between intensity of sand dune activity as a proxy of aeolian processes in desert environments, surface wind conditions, and surface soil moisture were traced. Overall, we have confirmed that tracking sandy desert aeolian environments for long-term observations is feasible with space-borne, multi-sensor observations when combined with

  3. In-situ study of migration and transformation of nitrogen in groundwater based on continuous observations at a contaminated desert site

    Science.gov (United States)

    Zuo, Rui; Jin, Shuhe; Chen, Minhua; Guan, Xin; Wang, Jinsheng; Zhai, Yuanzheng; Teng, Yanguo; Guo, Xueru

    2018-04-01

    The objective of this study was to explore the controlling factors on the migration and transformation of nitrogenous wastes in groundwater using long-term observations from a contaminated site on the southwestern edge of the Tengger Desert in northwestern China. Contamination was caused by wastewater discharge rich in ammonia. Two long-term groundwater monitoring wells (Wells 1# and 2#) were constructed, and 24 water samples were collected. Five key indicators were tested: ammonia, nitrate, nitrite, dissolved oxygen, and manganese. A numerical method was used to simulate the migration process and to determine the migration stage of the main pollutant plume in groundwater. The results showed that at Well 1# the nitrogenous waste migration process had essentially been completed, while at Well 2# ammonia levels were still rising and gradually transitioning to a stable stage. The differences for Well 1# and Well 2# were primarily caused by differences in groundwater flow. The change in ammonia concentration was mainly controlled by the migration of the pollution plume under nitrification in groundwater. The nitrification rate was likely affected by changes in dissolved oxygen and potentially manganese.

  4. Effect of desertification on productivity in a desert steppe.

    Science.gov (United States)

    Tang, Zhuangsheng; An, Hui; Deng, Lei; Wang, Yingying; Zhu, Guangyu; Shangguan, Zhouping

    2016-06-14

    Desertification, one of the most severe types of land degradation in the world, is of great importance because it is occurring, to some degree, on approximately 40% of the global land area and is affecting more than 1 billion people. In this study, we used a space-for-time method to quantify the impact of five different desertification regimes (potential (PD), light (LD), moderate (MD), severe (SD), and very severe (VSD)) on a desert steppe ecosystem in northern China to examine the relationship between the productivity of the vegetation and soil properties and to determine the mechanism underlying the effects of desertification on productivity. Our results showed that the effects of desertification on TP (total phosphorus) and AP (available phosphorus) were not significant, and desertification decreased productivity in the desert steppe as a result of direct changes to soil physical properties, which can directly affect soil chemical properties. Therefore, intensive grassland management to improve soil quality may result in the long-term preservation of ecosystem functions and services.

  5. Radiative forcing of the desert aerosol at Ouarzazate (Morocco)

    Science.gov (United States)

    Tahiri, Abdelouahid; Diouri, Mohamed

    2018-05-01

    The atmospheric aerosol contributes to the definition of the climate with direct effect, the diffusion and absorption of solar and terrestrial radiations, and indirect, the cloud formation process where aerosols behave as condensation nuclei and alter the optical properties. Satellites and ground-based networks (solar photometers) allow the terrestrial aerosol observation and the determination of impact. Desert aerosol considered among the main types of tropospheric aerosols whose optical property uncertainties are still quite important. The analysis concerns the optical parameters recorded in 2015 at Ouarzazate solar photometric station (AERONET/PHOTONS network, http://aeronet.gsfc.nasa.gov/) close to Saharan zone. The daily average aerosol optical depthτaer at 0.5μm, are relatively high in summer and less degree in spring (from 0.01 to 1.82). Daily average of the Angstrom coefficients α vary between 0.01 and 1.55. The daily average of aerosol radiative forcing at the surface range between -150W/m2 and -10 W/m2 with peaks recorded in summer, characterized locally by large loads of desert aerosol in agreement with the advections of the Southeast of Morocco. Those recorded at the Top of the atmosphere show a variation from -74 W/m2 to +24 W/m2

  6. Orbital radar studies of paleodrainages in the central Namib Desert

    Science.gov (United States)

    Lancaster, N.; Schaber, G.G.; Teller, J.T.

    2000-01-01

    Orbital radar images of the central Namib Desert show clearly the extent of relict fluvial deposits associated with former courses of the Tsondab and Kuiseb rivers. South of the Kuiseb River, radar data show the existence of a drainage network developed in calcrete-cemented late Tertiary fluvial deposits. The sand-filled paleovalleys are imaged as radar-dark tones in contrast to the radar-bright interfluves where the calcreted gravels occur. The drainage network developed as a result of local runoff from indurated gravels and channeled surface and subsurface flow to the sites of the many interdune lacustrine deposits found in the area. (C) Elsevier Science Inc., 2000.Orbital radar images of the central Namib Desert show clearly the extent of relict fluvial deposits associated with former courses of the Tsondab and Kuiseb rivers. South of the Kuiseb River, radar data show the existence of a drainage network developed in calcrete-cemented late Tertiary fluvial deposits. The sand-filled paleovalleys are imaged as radar-dark tones in contrast to the radar-bright interfluves where the calcreted gravels occur. The drainage network developed as a result of local runoff from indurated gravels and channeled surface and subsurface flow to the sites of the many interdune lacustrine deposits found in the area.

  7. Microenvironments and microscale productivity of cyanobacterial desert crusts

    Science.gov (United States)

    Garcia-Pichel, F.; Belnap, Jayne

    1996-01-01

    We used microsensors to characterize physicochemical microenvironments and photosynthesis occurring immediately after water saturation in two desert soil crusts from southeastern Utah, which were formed by the cyanobacteria Microcoleus vaginatus Gomont, Nostoc spp., and Scytonema sp. The light fields within the crusts presented steep vertical gradients in magnitude and spectral composition. Near-surface light-trapping zones were formed due to the scattering nature of the sand particles, but strong light attenuation resulted in euphotic zones only ca. 1 mm deep, which were progressively enriched in longer wavelengths with depth. Rates of gross photosynthesis (3.4a??9.4 mmol O2A?ma??2A?ha??1) and dark respiration (0.81a??3.1 mmol Oa??2A?ma??2A?ha??1) occurring within 1 to several mm from the surface were high enough to drive the formation of marked oxygen microenvironments that ranged from oxygen supersaturation to anoxia. The photosynthetic activity also resulted in localized pH values in excess of 10, 2a??3 units above the soil pH. Differences in metabolic parameters and community structure between two types of crusts were consistent with a successional pattern, which could be partially explained on the basis of the microenvironments. We discuss the significance of high metabolic rates and the formation of microenvironments for the ecology of desert crusts, as well as the advantages and limitations of microsensor-based methods for crust investigation.

  8. Prevalence of Mycoplasma ovipneumoniae in desert bighorn sheep in Arizona

    Science.gov (United States)

    Justice-Allen, Anne E.; Luedtke, Clint J.; Overstreet, Matthew; Cain, James W.; Stephenson, Thomas R.

    2011-01-01

    To assess the potential for an epizootic of pneumonia to result from either natural immigration or translocation, we compared the seroprevalence to Mycoplasma ovipneumoniae in several populations of desert bighorn sheep in Arizona. We collected blood samples and nasal or oropharyngeal swabs from 124 desert bighorn sheep (Ovis canadensis nelsoni) from 6 populations in Arizona in 2009 and 2010. M. ovipneumoniae organisms were detected by PCR in 22%, whereas antibodies to M. ovipneumoniae were detected in 47% of tested bighorn sheep. Mycoplasma antibodies were not found in 2 of 6 populations, indicating some bighorn sheep populations in Arizona are naïve to this bacterium. In contrast, others had seroprevalence rates up to 80%. We were able to compare seroprevalence rates and titers over time in 9 individuals (7 individuals included in the 124 bighorn sheep sampled in 2009 and 2010, and 2 individuals originally captured in 2006). Antibody titers persisted for 12 months in individuals from the Kofa National Wildlife Refuge (n = 7) while antibody titers appeared to decline in the Kanab Creek population (n = 2). M. ovipneumoniae is present or has been present in several, but not all, populations of bighorn sheep in Arizona. The results demonstrate the importance of routine health testing for future translocation efforts to reduce disease risk for naive populations.

  9. Origins and ecological consequences of pollen specialization among desert bees.

    Science.gov (United States)

    Minckley, R L; Cane, J H; Kervin, L

    2000-02-07

    An understanding of the evolutionary origins of insect foraging specialization is often hindered by a poor biogeographical and palaeoecological record. The historical biogeography (20,000 years before present to the present) of the desert-limited plant, creosote bush (Larrea tridentata), is remarkably complete. This history coupled with the distribution pattern of its bee fauna suggests pollen specialization for creosote bush pollen has evolved repeatedly among bees in the Lower Sonoran and Mojave deserts. In these highly xeric, floristically depauperate environments, species of specialist bees surpass generalist bees in diversity, biomass and abundance. The ability of specialist bees to facultatively remain in diapause through resource-poor years and to emerge synchronously with host plant bloom in resource-rich years probably explains their ecological dominance and persistence in these areas. Repeated origins of pollen specialization to one host plant where bloom occurs least predictably is a counter-example to prevailing theories that postulate such traits originate where the plant grows best and blooms most reliably Host-plant synchronization, a paucity of alternative floral hosts, or flowering attributes of creosote bush alone or in concert may account for the diversity of bee specialists that depend on this plant instead of nutritional factors or chemical coevolution between floral rewards and the pollinators they have evolved to attract.

  10. Radon concentration measurements in the desert caves of Saudi Arabia

    International Nuclear Information System (INIS)

    Al-Mustafa, Hanan; Al-Jarallah, M.I.; Fazal-ur-Rehman; Abu-Jarad, F.

    2005-01-01

    Beneath the harsh deserts of Saudi Arabia lie dark chambers and complex mazes filled with strange shapes and wondrous beauty. Radon concentration measurements have been carried out in the desert caves of Al-Somman Plateau in the Eastern Province of Saudi Arabia. Passive radon dosimeters, based on alpha particle etch track detectors with an inlet filter, were used in this study. A total of 59 dosimeters were placed in five caves for a period of six months. Out of 59 dosimeters, 37 could be collected for analysis. Measurements showed significant variations in radon concentrations in caves depending upon their natural ventilation. The results of the study show that the average radon concentration in the different caves ranges from 74 up to 451Bqm -3 . The average radon concentration in four of the caves was low in the range 74-114Bqm -3 . However, one cave showed an average radon concentration of 451Bqm -3 . Radon is not a problem for tourists in the majority of caves. However, sometimes it may imply some limitation to the working time of guides

  11. Radon concentration measurements in the desert caves of Saudi Arabia

    Energy Technology Data Exchange (ETDEWEB)

    Al-Mustafa, Hanan [Women College, P. O. Box 838, Dammam 31113 (Saudi Arabia); Al-Jarallah, M.I. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)]. E-mail: mibrahim@kfupm.edu.sa; Fazal-ur-Rehman [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Abu-Jarad, F. [Radiation Protection Unit, Environmental Protection Department, Saudi Aramco P.O. Box 13027, Dhahran 31311 (Saudi Arabia)

    2005-11-15

    Beneath the harsh deserts of Saudi Arabia lie dark chambers and complex mazes filled with strange shapes and wondrous beauty. Radon concentration measurements have been carried out in the desert caves of Al-Somman Plateau in the Eastern Province of Saudi Arabia. Passive radon dosimeters, based on alpha particle etch track detectors with an inlet filter, were used in this study. A total of 59 dosimeters were placed in five caves for a period of six months. Out of 59 dosimeters, 37 could be collected for analysis. Measurements showed significant variations in radon concentrations in caves depending upon their natural ventilation. The results of the study show that the average radon concentration in the different caves ranges from 74 up to 451Bqm{sup -3}. The average radon concentration in four of the caves was low in the range 74-114Bqm{sup -3}. However, one cave showed an average radon concentration of 451Bqm{sup -3}. Radon is not a problem for tourists in the majority of caves. However, sometimes it may imply some limitation to the working time of guides.

  12. Biological Soil Crusts: Webs of Life in the Desert

    Science.gov (United States)

    Belnap, Jayne

    2001-01-01

    Although the soil surface may look like dirt to you, it is full of living organisms that are a vital part of desert ecosystems. This veneer of life is called a biological soil crust. These crusts are found throughout the world, from hot deserts to polar regions. Crusts generally cover all soil spaces not occupied by green plants. In many areas, they comprise over 70% of the living ground cover and are key in reducing erosion, increasing water retention, and increasing soil fertility. In most dry regions, these crusts are dominated by cyanobacteria (previously called blue-green algae), which are one of the oldest known life forms. Communities of soil crusts also include lichens, mosses, microfungi, bacteria, and green algae. These living organisms and their by-products create a continuous crust on the soil surface. The general color, surface appearance, and amount of coverage of these crusts vary depending on climate and disturbance patterns. Immature crusts are generally flat and the color of the soil, which makes them difficult to distinguish from bare ground. Mature crusts, in contrast, are usually bumpy and dark-colored due to the presence of lichens, mosses, and high densities of cyanobacteria and other organisms.

  13. Particulate matter in Southwestern Africa cities of Cotonou (Benin) and Abidjan (Côte d'Ivoire).

    Science.gov (United States)

    Leon, J. F.; Djossou, J.; Liousse, C.; Akpo, A.; Veronique, Y.; Gardrat, E.; Bedou, M.; Bodjrenou, M.

    2017-12-01

    Air quality observations in the major cities of South-Western Africa still remains few with regards to economic growth and the large increase in the urban population. The main cities lying on the Gulf of Guinea experiences low air quality because of the contribution of local emissions and advection of pollutants from the African continent. We present in this paper new observations acquired from February 2015 to March 2017 in the major cities of Cotonou (Bénin) and Abidjan (Côte d'Ivoire). The PM2.5 mass concentration and carbon composition (elemental and organic carbon) were recorded on a weekly basis at 4 different locations representative of major emission sources, i.e. traffic emission, domestic fire and waste burning. Additionally, the aerosol optical depth (AOD) was also recorded daily inside and outside the cities. We observe large similarly between both cities. The mean PM2.5 concentration of around 30 µg.m-3 is coherent with previous studies for sub-Saharan western Africa and is 3 times higher than the concentrations recommended by the World Health Organization. The sampled collected at the domestic fire site shows a large pollution by smoking activity with an average concentration of 145 µg.m-3, nearly 5 times the traffic background. The seasonality of PM2.5 is affected by the contribution of desert dust and biomass burning emissions that is clearly observed from the AOD time series. We observe that dust events contribute sporadically to large amount of PM2.5, above 100 µg.m-3, during the dry seasons. Moreover, the biomass burning activity is also maximum before and during the dry season and contributes to increase the PM2.5 concentration. Low PM2.5 observed during the minor dry season can be explain by an enhancement of the atmospheric dispersion due to the increase in the wind intensity and the absence of biomass burning activity. We observe a significant difference in the carbonaceous aerosols between the traffic site in Abidjan and Cotonou. The

  14. Glacial Isostatic Adjustment Derived Boundary Conditions for Paleoclimate Simulation: the Refined ICE-6G_D (VM5a) Model and the Dansgaard-Oeschger Oscillation

    Science.gov (United States)

    Peltier, W. R.; Vettoretti, G.; Argus, D. F.

    2017-12-01

    Global models of the glacial isostatic adjustment (GIA) process are designed to fit a wide range of geophysical and geomorphological observations that simultaneously constrain the internal viscoelastic structure of Earths interior and the history of grounded ice thickness variations that has occurred over the most recent ice-age cycle of the Late Quaternary interval of time. The most recent refinement of the ICE-NG (VMX) series of such global models from the University of Toronto, ICE-6G_C (VM5a), has recently been slightly modified insofar as its Antarctic component is concerned to produce a "_D" version of the structure. This has been chosen to provide the boundary conditions for the next round of model-data inter-comparisons in the context of the international Paleoclimate Modeling Inter-comparison Project (PMIP). The output of PMIP will contribute to the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change which is now under way. A highly significant test of the utility of this latest model has recently been performed that is focused upon the Dansgaard-Oeschger oscillation that was the primary source of climate variability during Marine Isotope Stage 3 (MIS3) of the most recent glacial cycle. By introducing the surface boundary conditions for paleotopography and paleobathymetry, land-sea mask and surface albedo into the NCAR CESM1 coupled climate model configured at full one degree by one degree CMIP5 resolution, together with the appropriate trace gas and orbital insolation forcing, we show that the millennium timescale Dansgard-Oeschger oscillation naturally develops following spin- up of the model into the glacial state.

  15. Ancient geographical gaps and paleo-climate shape the phylogeography of an endemic bird in the sky islands of southern India.

    Science.gov (United States)

    Robin, V V; Sinha, Anindya; Ramakrishnan, Uma

    2010-10-13

    Sky islands, formed by the highest reaches of mountain tracts physically isolated from one another, represent one of the biodiversity-rich regions of the world. Comparative studies of geographically isolated populations on such islands can provide valuable insights into the biogeography and evolution of species on these islands. The Western Ghats mountains of southern India form a sky island system, where the relationship between the island structure and the evolution of its species remains virtually unknown despite a few population genetic studies. We investigated how ancient geographic gaps and glacial cycles have partitioned genetic variation in modern populations of a threatened endemic bird, the White-bellied Shortwing Brachypteryx major, across the montane Shola forests on these islands and also inferred its evolutionary history. We used bayesian and maximum likelihood-based phylogenetic and population-genetic analyses on data from three mitochondrial markers and one nuclear marker (totally 2594 bp) obtained from 33 White-bellied Shortwing individuals across five islands. Genetic differentiation between populations of the species correlated with the locations of deep valleys in the Western Ghats but not with geographical distance between these populations. All populations revealed demographic histories consistent with population founding and expansion during the Last Glacial Maximum. Given the level of genetic differentiation north and south of the Palghat Gap, we suggest that these populations be considered two different taxonomic species. Our results show that the physiography and paleo-climate of this region historically resulted in multiple glacial refugia that may have subsequently driven the evolutionary history and current population structure of this bird. The first avian genetic study from this biodiversity hotspot, our results provide insights into processes that may have impacted the speciation and evolution of the endemic fauna of this region.

  16. Ancient geographical gaps and paleo-climate shape the phylogeography of an endemic bird in the sky islands of southern India.

    Directory of Open Access Journals (Sweden)

    V V Robin

    2010-10-01

    Full Text Available Sky islands, formed by the highest reaches of mountain tracts physically isolated from one another, represent one of the biodiversity-rich regions of the world. Comparative studies of geographically isolated populations on such islands can provide valuable insights into the biogeography and evolution of species on these islands. The Western Ghats mountains of southern India form a sky island system, where the relationship between the island structure and the evolution of its species remains virtually unknown despite a few population genetic studies.We investigated how ancient geographic gaps and glacial cycles have partitioned genetic variation in modern populations of a threatened endemic bird, the White-bellied Shortwing Brachypteryx major, across the montane Shola forests on these islands and also inferred its evolutionary history. We used bayesian and maximum likelihood-based phylogenetic and population-genetic analyses on data from three mitochondrial markers and one nuclear marker (totally 2594 bp obtained from 33 White-bellied Shortwing individuals across five islands. Genetic differentiation between populations of the species correlated with the locations of deep valleys in the Western Ghats but not with geographical distance between these populations. All populations revealed demographic histories consistent with population founding and expansion during the Last Glacial Maximum. Given the level of genetic differentiation north and south of the Palghat Gap, we suggest that these populations be considered two different taxonomic species.Our results show that the physiography and paleo-climate of this region historically resulted in multiple glacial refugia that may have subsequently driven the evolutionary history and current population structure of this bird. The first avian genetic study from this biodiversity hotspot, our results provide insights into processes that may have impacted the speciation and evolution of the endemic fauna of

  17. Changes in precipitation isotope-climate relationships from temporal grouping and aggregation of weekly-resolved USNIP data: impacts on paleoclimate and environmental applications

    Science.gov (United States)

    Akers, P. D.; Welker, J. M.

    2015-12-01

    Spatial variations in precipitation isotopes have been the focus of much recent research, but relatively less work has explored changes at various temporal scales. This is partly because most spatially-diverse and long-term isotope databases are offered at a monthly resolution, while daily or event-level records are spatially and temporally limited by cost and logistics. A subset of 25 United States Network for Isotopes in Precipitation (USNIP) sites with weekly-resolution in the east-central United States was analyzed for site-specific relationships between δ18O and δD (the local meteoric water line/LMWL), δ18O and surface temperature, and δ18O and precipitation amount. Weekly data were then aggregated into monthly and seasonal data to examine the effect of aggregation on correlation and slope values for each of the relationships. Generally, increasing aggregation improved correlations (>25% for some sites) due to a reduced effect of extreme values, but estimates on regression variable error increased (>100%) because of reduced sample sizes. Aggregation resulted in small, but significant drops (5-25%) in relationship slope values for some sites. Weekly data were also grouped by month and season to explore changes in relationships throughout the year. Significant subannual variability exists in slope values and correlations even for sites with very strong overall correlations. LMWL slopes are highest in winter and lowest in summer, while the δ18O-surface temperature relationship is strongest in spring. Despite these overall trends, a high level of month-to-month and season-to-season variability is the norm for these sites. Researchers blindly applying overall relationships drawn from monthly-resolved databases to paleoclimate or environmental research risk assuming these relationships apply at all temporal resolutions. When possible, researchers should match the temporal resolution used to calculate an isotopic relationship with the temporal resolution of

  18. Climate change and runoff in south-western Australia

    Science.gov (United States)

    Silberstein, R. P.; Aryal, S. K.; Durrant, J.; Pearcey, M.; Braccia, M.; Charles, S. P.; Boniecka, L.; Hodgson, G. A.; Bari, M. A.; Viney, N. R.; McFarlane, D. J.

    2012-12-01

    SummaryThis paper presents the results of computer simulations of runoff from 13 major fresh and brackish river basins in south-western Australia (SWA) under climate projections obtained from 15 GCMs with three future global warming scenarios equivalent to global temperature rises of 0.7 °C, 1.0 °C and 1.3 °C by 2030. The objective was to apply an efficient methodology, consistent across a large region, to examine the implications of the best available projections in climate trends for future surface water resources. An ensemble of rainfall-runoff models was calibrated on stream flow data from 1975 to 2007 from 106 gauged catchments distributed throughout the basins of the study area. The sensitivity of runoff to projected changes in mean annual rainfall is examined using the climate 'elasticity' concept. Averaged across the study area, all 15 GCMs project declines in rainfall under all global warming scenarios with a median decline of 8% resulting in a median decline in runoff of 25%. Such uniformity in projections from GCMs is unusual. Over SWA the average annual runoff under the 5th wettest and 5th driest of the 45 projections of the 2030 climate declines by 10 and 42%, respectively. Under the 5th driest projection the runoff decline ranges from 53% in the northern region to 40% in the southern region. Strong regional variations in climate sensitivity are found with the proportional decline in runoff greatest in the northern region and the greatest volumetric declines in the wetter basins in the south. Since the mid 1970s stream flows into the major water supply reservoirs in SWA have declined by more than 50% following a 16% rainfall reduction. This has already had major implications for water resources planning and for the preservation of aquatic and riparian ecosystems in the region. Our results indicate that this reduction in runoff is likely to continue if future climate projections eventuate.

  19. Investigating Ultra-low Velocity Zones beneath the Southwestern Pacific

    Science.gov (United States)

    Carson, S. E.; Hansen, S. E.; Garnero, E.

    2017-12-01

    The core mantle boundary (CMB), where the solid silicate mantle meets the liquid iron-nickel outer core, represents the largest density contrast on our planet, and it has long been recognized that the CMB is associated with significant structural heterogeneities. One CMB structure of particular interest are ultra low-velocity zones (ULVZs), laterally-varying, 5-50 km thick isolated patches seen in some locations just above the CMB that are associated with increased density and reduced seismic wave velocities. These variable characteristics have led to many questions regarding ULVZ origins, but less than 40% of the CMB has been surveyed for the presence of ULVZs given limited seismic coverage of the lowermost mantle. Therefore, investigations that sample the CMB with new geometries are critical to further our understanding of ULVZs and their potential connection to other deep Earth processes. The Transantarctic Mountains Northern Network (TAMNNET), a 15-station seismic array that was recently deployed in Antarctica, provides a unique dataset to further study ULVZ structure with new and unique path geometry. Core-reflected ScP and PcP phases from the TAMNNET dataset particularly well sample the CMB in the vicinity of New Zealand in the southwestern Pacific, providing coverage between an area to the north where ULVZ structure has been previously identified and another region to the south, which shows no ULVZ evidence. By identifying and modeling pre- and post-cursor ScP and PcP energy, we are exploring a new portion of the CMB with a goal of better understanding potential ULVZ origins. Our study area also crosses the southern boundary of the Pacific Large Low Shear Velocity Province (LLSVP); therefore, our investigations may allow us to examine the possible relationship between LLSVPs and ULVZs.

  20. Uranium Hydrogeochemical and Stream Sediment Reconnaissance in southwestern Montana

    Energy Technology Data Exchange (ETDEWEB)

    Broxton, D.E.

    1978-02-01

    The Los Alamos Scientific Laboratory conducted a Hydrogeochemical and Stream Sediment Reconnaissance in southwestern Montana from early August to mid-October of 1976. A total of 1240 water and 1933 sediment samples were collected from 1994 locations at a nominal density of one location per 10 km/sup 2/. The water samples were collected from streams, wells, and springs; sediment samples were taken at streams and springs. All samples were analyzed at Los Alamos for total uranium by fluorometry or delayed-neutron counting. The uranium content of water samples ranges from below the detection limit (less than 0.3 ppB) to 45.30 ppB and has a mean value of 1.40 ppB. The uranium content of the sediment samples ranges between 0.20 and 206.80 ppM and averages 6.12 ppM. The chosen uranium anomaly threshold value was 7 ppB for surface waters (streams), 9 ppB for groundwaters (wells and springs), and 25 ppM for all sediment samples. The study area consists of the following lithologic groups: Precambrian basement complex, Precambrian Belt metasediments, Paleozoic and Mesozoic shelf sediments, Cretaceous and early Tertiary volcanic and plutonic rocks, Laramide orogenic clastic sediments, and middle to late Tertiary volcanic rocks and intermontane basin sediments. Most of the anomalous water and sediment samples with well-developed dispersion trains occur in areas underlain by or adjacent to silicic plutonic rocks of the Idaho and Boulder batholiths. These anomalies may indicate the presence of uraniferous veins and pegmatites similar to those already known to exist in the area. Fewer anomalous water samples occur in areas underlain by Precambrian basement complex and Tertiary basin fill.